CN114589403A - Welding method and system for reducing laser welding heat affected zone and refining structure - Google Patents
Welding method and system for reducing laser welding heat affected zone and refining structure Download PDFInfo
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K26/00—Working by laser beam, e.g. welding, cutting or boring
- B23K26/20—Bonding
- B23K26/21—Bonding by welding
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- B—PERFORMING OPERATIONS; TRANSPORTING
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- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K26/00—Working by laser beam, e.g. welding, cutting or boring
- B23K26/12—Working by laser beam, e.g. welding, cutting or boring in a special atmosphere, e.g. in an enclosure
- B23K26/1224—Working by laser beam, e.g. welding, cutting or boring in a special atmosphere, e.g. in an enclosure in vacuum
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K26/00—Working by laser beam, e.g. welding, cutting or boring
- B23K26/12—Working by laser beam, e.g. welding, cutting or boring in a special atmosphere, e.g. in an enclosure
- B23K26/123—Working by laser beam, e.g. welding, cutting or boring in a special atmosphere, e.g. in an enclosure in an atmosphere of particular gases
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- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
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- B23K26/00—Working by laser beam, e.g. welding, cutting or boring
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Abstract
The invention belongs to the technical field of laser welding, and particularly discloses a welding method and a welding system for reducing a laser welding heat affected zone and refining a structure. The method comprises the following steps: preprocessing the surface of a workpiece to be welded; s2, setting welding process parameters and working parameters of the conformal condensation plate; s3, integrating an ultrasonic generating device, wherein the laser head and the ultrasonic generating device are arranged at intervals; s4, welding the workpiece in a vacuum environment according to the set welding process parameters, moving the laser head according to a preset path and speed, operating the conformal condensation plate, and simultaneously starting an ultrasonic generating device to perform ultrasonic vibration on the welding line of the workpiece; s5 recrystallization annealing the workpiece at a prescribed temperature. The invention accurately regulates and controls the welding energy distribution, simultaneously assists the following condensation plate with self-adaptive temperature regulation and the following ultrasonic treatment of the welding line, further optimizes and controls the laser welding forming and quality, and improves the uniformity of the structure performance so as to reduce the heat affected zone of the laser welding and refine the structure.
Description
Technical Field
The invention belongs to the field of laser welding, and particularly relates to a welding method and a welding system for reducing a laser welding heat affected zone and refining a structure.
Background
In the fusion welding process, metal materials are fused under the action of a heat source to form a welding seam, and a certain range of area affected by heat in the welding process exists between the welding seam metal and a base metal, namely a heat affected area. The welding seam area and the heat affected area are different from the base metal in tissue form due to the effect of welding heat circulation, and the tissue form of the welding seam area and the tissue form of the heat affected area are often large in size, so that the service performance of a welding joint is affected. In practical engineering application, certain requirements are often set on the width of a heat affected zone and the structure form of a welding seam. Therefore, the reduction of the width of the heat affected zone and the refinement of the structure of the weld zone have important significance for improving the service performance of the welded joint.
The welding heat input has important influence on the width of a welding heat affected zone and the tissue form of a welding seam, and researches in recent years prove that the vacuum laser welding can obviously reduce the laser welding heat input, and the vacuum laser welding can realize more than twice of the fusion depth of the conventional laser welding under the same welding heat input. Chinese patent CN106271061B discloses an unconventional low-temperature gas-shielded laser welding method, which adopts a low-temperature gas-shielded laser welding method to improve a welding shielding gas feeding device on the basis of conventional laser welding. However, the method adopts low-temperature protective gas to protect and cool the molten pool and the vicinity thereof, the requirement on the atmosphere environment is high, the control is difficult, and meanwhile, the groove opening of the base material is still needed and the one-step forming of the connection of the medium and thick plates cannot be met, so that the process is complex. Patent document CN201210002191.6 discloses a vacuum laser welding apparatus and method, which is described too briefly, and does not utilize a swinging laser tuning energy field, and thus, the structure uniformity and performance consistency of a large-thickness welding joint in the thickness direction cannot be guaranteed.
Based on the above defects and shortcomings, there is a need in the art to provide a welding method for reducing a heat affected zone of laser welding and refining the structure, which can directly cool a welded substrate at any time, perform optimization design on the process parameters of vacuum laser welding, and perform a combined process of shock vibration and thermal treatment recrystallization annealing after welding, so as to achieve the purposes of reducing the width of the heat affected zone of welding and refining the grain size of the welded joint.
Disclosure of Invention
Aiming at the defects or the improvement requirements of the prior art, the invention provides a welding method and a welding system for reducing a laser welding heat affected zone and refining the structure, wherein the welding method for reducing the laser welding heat affected zone and refining the structure is correspondingly designed by combining the characteristics of vacuum laser welding and the control of welding process parameters thereof, the laser output power is synchronously regulated and controlled in the swinging process through a high vacuum environment and a swinging laser tuning energy field, meanwhile, a follow-up condensing plate with self-adaptive temperature adjustment is assisted to cool a welding substrate at any time, and ultrasonic vibration impact is used for carrying out follow-up treatment on the welding seam, so that the welding energy distribution is accurately regulated and controlled, the laser welding forming and quality are further optimized and controlled, the uniformity of the structure performance is improved, the laser welding heat affected zone and the structure refinement are reduced, one-step forming can be realized, and the welding quality is higher, effectively inhibit the generation of the plume and the splash, improve the welding stability and effectively reduce the defects of common air holes, depressions, back welding beading and the like.
Therefore, the vacuum laser welding and the substrate in the welding-following cold region can obviously reduce the welding heat input, increase the cooling speed, and carry out the combined process of impact vibration and thermal treatment recrystallization annealing after welding, thereby achieving the aims of reducing the width of the welding heat affected region and refining the grain size of the welding line.
To achieve the above object, according to one aspect of the present invention, there is provided a welding method for reducing a heat affected zone of laser welding and for structure refinement, comprising the steps of:
s1, preprocessing the surface of a workpiece to be welded, then placing the preprocessed workpiece on a workbench, and arranging a conformal condensation plate between the workpiece and the workbench;
s2, setting welding process parameters according to the material of the workpiece and the thickness of the workpiece, and setting working parameters of the conformal condensation plate;
s3, integrating an ultrasonic generating device on a laser head for welding, wherein the laser head and the ultrasonic generating device are arranged at intervals;
s4, providing a vacuum environment in the welding process, welding the workpiece in the vacuum environment according to set welding process parameters, enabling the laser head to move according to a preset path and speed, enabling the conformal condensation plate to work, and simultaneously starting an ultrasonic generating device to perform ultrasonic vibration on a welding seam of the workpiece;
s5, after the workpiece is welded and all welding lines are subjected to ultrasonic vibration, carrying out recrystallization annealing on the workpiece at the specified temperature.
Further preferably, in step S2, the welding process parameters include vacuum pressure, laser power, welding speed and defocus, wherein,
the vacuum pressure is 100-10000 Pa, the laser power of the laser is 3500-5500W, the welding speed is 0.3-1.8 m/min, and the defocusing amount is-10 mm.
More preferably, in step S2, the operating temperature of the conformal cooling plate ranges from-50 ℃ to 20 ℃, and the flow rate of the coolant is adaptively adjusted according to the workpiece temperature and the temperature of the conformal cooling plate.
Preferably, in step S3, the laser head performs welding according to an oscillating path, and the oscillating is realized by oscillating an internal galvanometer of the laser head, so as to convert the light spot output by the laser head into an oscillating light spot, wherein the motion track of the oscillating light spot is generally one or more of a straight line, a circle, a figure 8, an infinity, a square or a triangle, and the special pattern can be realized by programming and controlling the oscillating of the internal galvanometer of the laser head.
Preferably, the swing amplitude of the swing light spot is 0.4-10 mm, and the swing is realized by controlling the cooperative high-speed motion of the galvanometer inside the laser head on an X, Y axis.
More preferably, in step S5, the workpiece is placed in a heat treatment furnace and recrystallization annealing is performed at 550 to 750 ℃.
More preferably, in step S2, the maximum thickness of the workpiece is determined by the upper limit of the laser head power and does not exceed 200 mm.
As a further preference, the pretreatment comprises: and (3) processing the front surface and the back surface of the part to be welded of the workpiece to be smooth, and polishing, pickling or laser cleaning the surface of the part to be welded.
According to another aspect of the present invention, there is also provided a welding system for reducing a heat affected zone of laser welding and for texture refinement, comprising:
the pre-welding pretreatment mechanism is used for pretreating the surface of a workpiece to be welded;
the welding tool is used for placing the pretreated workpiece on a welding platform in the vacuum chamber;
the conformal condensation plate is arranged between the welding tool and the workpiece and is used for cooling the welding seam of the workpiece in real time;
the swinging laser path planning mechanism is used for placing the laser head in a vacuum chamber according to actual conditions, adjusting the shape of a swinging laser spot to a required shape, aligning the spot to a welding spot, and determining that the spot walking path covers the whole welding seam gap through a walking mechanism or a welding seam tracking device;
the laser swing welding parameter control module is used for setting corresponding welding process parameters such as welding speed, welding power and defocusing amount according to actual welding requirements, adjusting swing parameters such as a laser swing mode, a swing frequency and a swing amplitude according to the performance requirements of a welding seam and welding gap adaptability, and optimally regulating and controlling laser energy distribution in a welding process until welding is finished;
the laser welding mechanism comprises a laser head, and the laser head is in communication connection with the laser swing welding parameter control module and the swing laser path planning mechanism and is used for performing vacuum laser welding on a workpiece;
the ultrasonic generating device is arranged at intervals with the laser head and is used for carrying out ultrasonic vibration on the welding line of the workpiece;
and the recrystallization annealing mechanism is used for carrying out recrystallization annealing at a specified temperature on the workpiece after the workpiece is welded and all welding lines are subjected to ultrasonic vibration.
More preferably, the working temperature range of the conformal condensation plate is-50 ℃ to 20 ℃.
Generally, compared with the prior art, the above technical solution conceived by the present invention mainly has the following technical advantages:
1. according to the invention, through a high vacuum environment and a swinging laser tuning energy field, the output power of laser is synchronously regulated and controlled in the swinging process, meanwhile, the walk condensing plate with self-adaptive temperature adjustment is assisted to cool a welding substrate at any time, and ultrasonic vibration impact is used for carrying out follow-up treatment on a welding seam, so that the welding energy distribution is accurately regulated and controlled, the laser welding forming and quality is optimized and controlled, the tissue performance uniformity is improved, the laser welding heat affected zone is reduced, the tissue is refined, the one-time forming can be realized, the welding quality is higher, the generation of brilliance and splashing is effectively inhibited, the welding stability is improved, and the defects of common pores, recesses, back welding beading and the like are effectively reduced.
2. The laser oscillating spot shape is a laser oscillating walking path, the laser oscillation is realized by controlling the cooperative high-speed motion of an internal vibrating mirror of the laser head on an X, Y axis, the oscillating spot shape is generally one or more of a straight line, a circle, a figure 8, an infinity, a square or a triangle, a special figure can be realized by controlling the oscillation of the internal vibrating mirror of the laser head through programming, and the laser energy distribution in the welding process is optimally regulated and controlled in an oscillating laser regulation and control mode.
3. Compared with the conventional single laser vacuum welding, the method for performing energy field tuning by using the swing laser is added, the stability of the vacuum laser welding is improved, the effect of shaping the welding seam is achieved, the upper width and the lower width of the welding joint are higher in consistency, the tissue performance of the welding joint in the thickness direction is more uniform, and the welding quality is improved.
4. The vacuum chamber of the invention can convey dry high-purity inert gas to the chamber under the pressure of 1000Pa, and the dynamic balance of air inlet and exhaust in the chamber is controlled to be adjusted to the environmental condition of specified vacuum degree, and the welding depth can be doubled in the high-vacuum environment.
5. According to the invention, through searching the nonlinear mapping relation between the welding process parameters and the quality of the welding seam, the optimal welding process parameters are searched according to the welding quality, the plate thickness and the like, the laser welding forming and quality are optimally regulated and controlled, the uniformity of the structure performance is improved, and the heat affected zone of the laser welding is reduced and the structure is refined.
Drawings
FIG. 1 is a flow chart of a welding method for reducing the heat affected zone of laser welding and for texture refinement in accordance with a preferred embodiment of the present invention;
FIG. 2 is a schematic view of the apparatus involved in a welding method of the present invention for reducing the heat affected zone of laser welding and for texture refinement;
FIG. 3 is a schematic view of the microstructure of a joint obtained by welding using the method of the present invention;
FIG. 4 is a microstructural characterization of different regions of a joint after welding using the method of the present invention.
In all the figures, the same reference numerals denote the same features, in particular: 1-laser head, 2-vacuum chamber, 3-connecting seat, 4-ultrasonic generating device, 5-workpiece to be processed, 6-fixture and 7-conformal condensation plate.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the respective embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
As shown in fig. 1 and fig. 2, a welding method for reducing a heat affected zone of laser welding and refining a structure according to an embodiment of the present invention includes the following steps:
s1, the surface of the workpiece to be welded is pretreated, then the pretreated workpiece is placed on a workbench, and a conformal condensation plate is arranged between the workpiece and the workbench.
In the pretreatment process, the front surface and the back surface of the part to be welded of the workpiece are processed to be smooth, and the surface of the part to be welded is polished, pickled or laser cleaned. More specifically, the part to be welded of the workpiece is processed into required precision according to the requirement, a surface oxidation film is removed by polishing with abrasive paper, then the workpiece is soaked in acetone and cleaned with ultrasonic waves to remove oil stains, and the polished or cleaned workpiece to be welded is fixed on a welding tool fixture and is placed on a workbench in a vacuum cabin.
In this embodiment, the laser head for welding is placed in a vacuum chamber, in such a way that the workpiece to be welded and the laser head are located in a set vacuum environment. A workbench is arranged in the vacuum chamber, and a welding tool is arranged on the workbench and used for placing a preprocessed workpiece on the welding workbench in the vacuum chamber. Correspondingly, a conformal condensation plate is arranged between the workbench and the workpiece and used for cooling the welding seam of the workpiece in real time. In a preferred embodiment of the invention, the conformal condensation plate comprises a plate body and a cooling liquid flow channel arranged in the plate body, and the temperature and the flow rate of the cooling liquid are controlled, so that the refrigeration working temperature range provided by the conformal condensation plate is-50 ℃ to 20 ℃. Of course, the above description is only one embodiment of the present invention. According to the invention, the flow velocity of the cooling liquid is self-adaptively adjusted according to the temperature of the workpiece and the temperature of the conformal condensation plate. In this way, the welded substrate is directly cooled at any time, so as to achieve the aims of reducing the width of the welding heat affected zone and refining the grain size of the welding seam.
S2, setting welding process parameters according to the material of the workpiece and the thickness of the workpiece, and setting working parameters of the conformal condensation plate.
In the preferred embodiment of the invention, the welding process parameters comprise vacuum pressure, laser power, welding speed and defocusing amount, wherein the vacuum pressure is 100-10000 Pa, the laser power of the laser is 3500-5500W, the welding speed is 0.3-1.8 m/min, and the defocusing amount is-10 mm.
Of course, the above are only the welding process parameter ranges of the preferred embodiment of the present invention. In the invention, the welding process parameters are optimized and calculated according to the welding process parameters and the welding seam parameters of the existing vacuum welding to obtain the optimal welding process parameters.
In an embodiment of the present invention, firstly, welding parameters are extracted according to a large number of welding line photographs, where the welding line parameters include a welding line width, a welding area fine grit, a welding depth, and a bubble number, and an evaluation function of welding quality is constructed according to the welding line parameters:
A(x)＝∑αiWi
wherein A (x) is an evaluation function, WiIs the ith weld parameter, αiThe weight of the ith weld parameter is constant.
And then, establishing a training data set according to the historical welding process parameters and the corresponding plate thickness, taking the training data set as the input of a support vector machine model, taking the corresponding welding quality parameters as the output of the support vector machine model, and optimally training the support vector machine model to obtain the nonlinear mapping relation between the vacuum welding parameters, the corresponding plate thickness and the welding seam parameters. And constructing a neural network model by taking the vacuum welding parameters, the nonlinear mapping relation between the corresponding plate thickness and the welding seam parameters and the evaluation function as target functions and the welding process parameters and the corresponding plate thickness as constraint conditions, and performing multi-objective optimization on the welding process parameters according to set iteration termination conditions to obtain an optimal welding process parameter set corresponding to the plate thickness. In a preferred embodiment of the present invention, the neural network model may employ the NSGA-II model.
The support vector machine model is constructed by selecting a Gaussian kernel function, wherein the expression of the Gaussian kernel function is as follows:
wherein x and d are variables of input, xiFor the ith sample data, xjFor jth sample data, σ2Is the nucleus width parameter, d' is the sheet thickness, w1Is a first weight, w2Is the second weight.
Meanwhile, in the optimization process, a Gaussian kernel function is selected to construct a support vector machine model. And performing parameter optimization by adopting five-fold cross validation to determine the optimal parameter combination of the penalty parameter of the support vector machine model and the kernel width parameter of the Gaussian kernel function so as to obtain the optimally trained support vector machine model.
The working parameters of the conformal condensation plate can be directly set according to the vacuum welding parameters. In a preferred embodiment of the invention, the conformal condensation plate is provided with a temperature sensor for directly detecting the temperature of the workpiece and the conformal condensation plate, and adjusting the working temperature according to the temperature of the workpiece and the conformal condensation plate so as to directly cool the welding substrate at any time.
S3, an ultrasonic generating device is integrated on a laser head for welding, and the laser head and the ultrasonic generating device are arranged at intervals. In this step, the laser head welds according to the swing walking route, is realized by the inside mirror oscillation that shakes of laser head to with the facula of laser head output turns into the swing facula, the orbit of swing facula motion generally is one or several kinds in straight line, circular, 8 font, infinity shape, square or triangle-shaped, and the inside mirror oscillation that shakes of special figure usable programming control laser head realizes.
Preferably, the swing amplitude of the swing light spot is 0.4-10 mm, and the control is realized by controlling the cooperative high-speed motion of the laser head internal galvanometer at an X, Y axis.
Specifically, as shown in fig. 2, the laser welding mechanism further comprises a laser driving base and a laser driving assembly, wherein a laser head 1 and an ultrasonic generating device 4 are arranged on the laser driving base, and the laser head 1 and the ultrasonic generating device 4 are arranged at intervals, so that after the laser head welds a workpiece, the ultrasonic generating device 4 performs ultrasonic vibration impact on the weld joint, on one hand, tiny air holes generated in the welding process are removed, on the other hand, the grain size of the weld joint is refined, and the welding heat influence area is reduced.
In the invention, the laser head 1 and the ultrasonic generating device 4 work independently without influence, namely, the laser head 1 is in front and performs laser welding on a workpiece according to a preset motion track, and the ultrasonic generating device 4 is behind and performs ultrasonic vibration impact on a molten pool at the welding position. Further, in order to realize the case where the locus of the oscillating spot movement is circular, 8-shaped, infinity-shaped, square or triangular, in the present invention, the distance between the laser head 1 and the ultrasonic generator 4 is an integer number of cycles, and in this way, the movement locus of the laser head 1 and the ultrasonic generator 4 is made to coincide.
S4 provides a vacuum environment in the welding process, the workpiece is welded in the vacuum environment according to set welding technological parameters, the laser head moves according to a preset path and speed, the conformal condensation plate works, and meanwhile, the ultrasonic generating device is started to perform ultrasonic vibration on the welding line of the workpiece. In the step, the vacuum environment and the action of the swing laser and the ultrasonic generating device accelerate the flow of the molten pool, are beneficial to the escape of pores and effectively eliminate metallurgical pores generated in the welding process.
S5, after the workpiece is welded and all welding lines are subjected to ultrasonic vibration, carrying out recrystallization annealing on the workpiece at the specified temperature.
According to another aspect of the present invention, there is also provided a welding system for reducing a heat affected zone of laser welding and for texture refinement, comprising: the pre-welding pretreatment mechanism is used for pretreating the surface of a workpiece to be welded; the welding tool is used for placing the pretreated workpiece on a welding workbench in a vacuum chamber; the conformal condensation plate is arranged between the welding tool and the workpiece and is used for cooling the welding seam of the workpiece in real time; the swinging laser path planning mechanism is used for placing the laser head in a vacuum chamber according to actual conditions, adjusting the shape of a swinging laser spot to a required shape, aligning the spot to a welding spot, and determining that the spot walking path covers the whole welding seam gap through a walking mechanism or a welding seam tracking device; the laser swing welding parameter control module is used for setting corresponding welding process parameters such as welding speed, welding power and defocusing amount according to actual welding requirements, adjusting swing parameters such as a laser swing mode, a swing frequency and a swing amplitude according to welding seam performance requirements and welding gap adaptability, and optimally regulating and controlling laser energy distribution in a welding process until welding is completed; the laser welding mechanism comprises a laser head, and the laser head is in communication connection with the laser swing welding parameter control module and the swing laser path planning mechanism and is used for performing vacuum laser welding on a workpiece; the ultrasonic generating device is arranged at intervals with the laser head and is used for carrying out ultrasonic vibration on the welding line of the workpiece; and the recrystallization annealing mechanism is used for carrying out recrystallization annealing at a specified temperature on the workpiece after the workpiece is welded and all welding lines are subjected to ultrasonic vibration.
In the system, the system further comprises a control mechanism, wherein the control mechanism is used for being in communication connection with the following condensation plate, the swinging laser path planning mechanism, the laser swinging welding parameter control module, the laser welding mechanism and the ultrasonic generating device and used for controlling the cooperative work of the whole mechanism. Furthermore, in the invention, the control mechanism is also integrated with the optimization algorithm designed by the method, and meanwhile, the welding process parameters and the welding seam parameters of each welding are collected and stored, so that when the data reaches a certain amount, the optimization algorithm is updated by adopting historical data and new data.
In the system, the working temperature range of the conformal condensation plate is-50 ℃ to 20 ℃.
In the system, the laser welding mechanism further comprises a laser driving base and a laser driving assembly, the laser driving base is provided with a laser head 1 and an ultrasonic generating device 4, the laser head 1 and the ultrasonic generating device 4 are arranged at intervals, and in this way, after the laser head welds a workpiece, the ultrasonic generating device 4 performs ultrasonic vibration impact on the weld joint, so that on one hand, a tiny air hole generated in the welding process is removed, on the other hand, the size of weld joint grains is refined, and the welding heat influence area is reduced.
In the system, the laser head 1 and the ultrasonic generating device 4 work independently without influence, namely the laser head 1 performs laser welding on a workpiece according to a preset motion track in front, and the ultrasonic generating device 4 performs ultrasonic vibration impact on a molten pool at the welding position in back. Further, in order to realize the case where the locus of the oscillating spot movement is circular, 8-shaped, infinity-shaped, square or triangular, in the present invention, the distance between the laser head 1 and the ultrasonic generator 4 is an integer number of cycles, and in this way, the movement locus of the laser head 1 and the ultrasonic generator 4 is made to coincide.
In the system, the conformal condensation plate is provided with a temperature sensor which is used for directly detecting the temperature of the workpiece and the conformal condensation plate and adjusting the working temperature according to the temperature of the workpiece and the conformal condensation plate so as to directly cool the welding substrate at any time.
Example 1
The method comprises the following steps: in the welding, a CO2 gas laser, a YAG solid laser, a semiconductor laser, and a fiber laser can be used as the laser.
Step two: and (3) fixing the polished or cleaned workpiece 5 to be machined on a welding tool clamp 6, and placing the workpiece on a workbench in the vacuum chamber 2, wherein the workbench is provided with a conformal condensation plate 7.
Step three: the ultrasonic wave generating device 4 is fixed on the laser head 1 by a special clamp 3, so that the ultrasonic vibration impact after welding can be realized by controlling the laser head without light emission after the laser welding is finished.
Step four: and vacuumizing the vacuum chamber 2, wherein the vacuum pressure is 100-10000 Pa.
Step five: the vacuum laser welding specifically comprises the following steps:
s51: according to the thickness of the workpiece 5 to be welded, the laser power is 3500-5500W, the welding speed is 0.3-1.8 m/min, and the defocusing amount is-10 mm.
S52: the temperature range of the conformal condensation plate 7 is-50 ℃ to 20 ℃.
S53: immediately after welding, the ultrasonic generator 4 is turned on and the weld is vibrated by the ultrasonic wave.
Step six: and after the welding is finished, breaking the space, taking out the welding test piece, putting the welding test piece into a heat treatment furnace, and carrying out recrystallization annealing at 550-750 ℃.
In the above embodiment, the size and the form of the vacuum chamber 2 can be adjusted according to actual requirements, and the designated vacuum degree should be 100-10000 Pa.
Example 2
In this embodiment, a 20mm thick aluminum alloy joint is welded by a vacuum swing laser welding method, the laser adopts a fast-open high-power laser, the maximum power is 10000W, the laser head is an IPG swing laser welding head, and other devices include 1 pick-up robot, a vacuum pumping system and a vacuum chamber.
The method comprises the following steps: removing an oxide film on the surface of a workpiece to be welded by using a laser cleaning method;
step two: and placing the to-be-welded workpiece which is well polished, acid-washed or laser-cleaned on a welding workbench in a vacuum chamber, and placing a follow-up condensation plate on the workbench. The area of the trailing cold plate covers at least the aluminum alloy joint. And then fixing the workpiece by using a tool clamp suitable for the structure and the size of the weldment.
Step three: the shape of the swinging laser facula is adjusted to be a circular facula, the center of the facula is aligned to the center of the welding spot, the facula walking path is determined to cover the whole welding seam gap through the adjustment of the walking mechanism of the welding platform in the vacuum chamber, and the welding seam gap is 2 mm.
Step four: and (3) closing the vacuum cabin door, opening the electric control baffle valve of the vacuum cabin, opening the vacuumizing pump set, opening the protective gas inlet valve when the vacuum cabin is pumped to the pressure below 1kPa, conveying dry high-purity inert gas into the cabin, setting automatic adjustment, and dynamically balancing air inlet and air exhaust in the cabin to be adjusted to the vacuum degree of 1000Pa for welding.
Step five: setting the welding speed at 0.3m/min, the welding power at 9000W, the defocusing amount at-5 mm, the swinging laser frequency at 150Hz, the swinging amplitude at 0.3mm, and the temperature range of the conformal condensation plate 7 at-50-20 ℃. Meanwhile, the ultrasonic wave generating device 4 is started immediately after welding, and the weld is vibrated by using ultrasonic waves.
Step six: and after the welding is finished, breaking the space, taking out the welding test piece, putting the welding test piece into a heat treatment furnace, and carrying out recrystallization annealing at 750 ℃.
It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (10)
1. A welding method for reducing a heat affected zone of laser welding and refining a structure is characterized by comprising the following steps of:
s1, preprocessing the surface of a workpiece to be welded, then placing the preprocessed workpiece on a workbench, and arranging a conformal condensation plate between the workpiece and the workbench;
s2, setting welding process parameters according to the material of the workpiece and the thickness of the workpiece, and setting working parameters of the conformal condensation plate;
s3, integrating an ultrasonic generating device on a laser head for welding, wherein the laser head and the ultrasonic generating device are arranged at intervals;
s4, providing a vacuum environment in the welding process, welding the workpiece in the vacuum environment according to set welding process parameters, enabling the laser head to move according to a preset path and speed, enabling the conformal condensation plate to work, and simultaneously starting an ultrasonic generating device to perform ultrasonic vibration on a welding seam of the workpiece;
s5, after the workpiece is welded and all welding lines are subjected to ultrasonic vibration, carrying out recrystallization annealing on the workpiece at the specified temperature.
2. A welding method for reducing the heat affected zone of laser welding and for texture refinement as claimed in claim 1, wherein in step S2, the welding process parameters include vacuum pressure, laser power, welding speed and defocus, wherein,
the vacuum pressure is 100-10000 Pa, the laser power of the laser is 3500-5500W, the welding speed is 0.3-1.8 m/min, and the defocusing amount is-10 mm.
3. A welding method with reduced heat affected zone and refined structure for laser welding as claimed in claim 1, wherein in step S2, the working temperature of the conformal cooling plate is in the range of-50 deg.C to 20 deg.C, and the flow rate of the cooling liquid is adaptively adjusted according to the workpiece temperature and the temperature of the conformal cooling plate.
4. The welding method of claim 1, wherein in step S3, the laser head performs welding according to an oscillating path, which is implemented by oscillating an internal oscillating mirror of the laser head, so as to convert the light spot output from the laser head into an oscillating light spot, wherein the oscillating light spot has a motion trajectory of one or more of a straight line, a circle, a figure 8, an infinity shape, a square shape or a triangle, and the special pattern can be implemented by programming the oscillating mirror of the laser head.
5. A welding method for reducing the heat affected zone of laser welding and realizing the tissue refinement of the welding method as claimed in claim 4, characterized in that the oscillation amplitude of the oscillation light spot is 0.4-10 mm, and the oscillation amplitude is realized by controlling the cooperative high-speed movement of an internal galvanometer of the laser head at X, Y axes.
6. A welding method with reduced heat affected zone and finer structure for laser welding according to any one of claims 1 to 5, wherein in step S5, the workpiece is placed in a heat treatment furnace for recrystallization annealing at 550 to 750 ℃.
7. A welding method with reduced heat affected zone and finer structure for laser welding as claimed in any one of claims 1 to 5 wherein in step S2 the maximum thickness of said workpiece is determined by the upper power limit of the laser head and does not exceed 200 mm.
8. A welding method for reducing the heat affected zone of laser welding and for texture refinement as claimed in any one of claims 1 to 5, wherein said pre-treatment comprises: and (3) processing the front surface and the back surface of the part to be welded of the workpiece to be smooth, and polishing, pickling or laser cleaning the surface of the part to be welded.
9. A welding system for reducing a heat affected zone of a laser weld and for texture refinement, comprising:
the pre-welding pretreatment mechanism is used for pretreating the surface of a workpiece to be welded;
the welding tool is used for placing the pretreated workpiece on a welding workbench in a vacuum chamber;
the conformal condensation plate is arranged between the welding tool and the workpiece and is used for cooling the welding seam of the workpiece in real time;
the swinging laser path planning mechanism is used for placing the laser head in a vacuum chamber according to actual conditions, adjusting the shape of a swinging laser spot to a required shape, aligning the spot to a welding spot, and determining that the spot walking path covers the whole welding seam gap through a walking mechanism or a welding seam tracking device;
the laser swing welding parameter control module is used for setting corresponding welding process parameters such as welding speed, welding power and defocusing amount according to actual welding requirements, adjusting swing parameters such as a laser swing mode, a swing frequency and a swing amplitude according to welding seam performance requirements and welding gap adaptability, and optimally regulating and controlling laser energy distribution in a welding process until welding is completed;
the laser welding mechanism comprises a laser head, and the laser head is in communication connection with the laser swing welding parameter control module and the swing laser path planning mechanism and is used for performing vacuum laser welding on a workpiece;
the ultrasonic generating device is arranged at intervals with the laser head and is used for carrying out ultrasonic vibration on the welding line of the workpiece;
and the recrystallization annealing mechanism is used for carrying out recrystallization annealing at a specified temperature on the workpiece after the workpiece is welded and all welding lines are subjected to ultrasonic vibration.
10. A welding system for reducing the heat affected zone of laser welding and for achieving finer structure as defined in claim 9, wherein said conformal cooling plate has an operating temperature in the range of-50 ℃ to 20 ℃.
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