CN118180672B - Splash suppression method and device for ultra-high power laser welding process - Google Patents
Splash suppression method and device for ultra-high power laser welding process Download PDFInfo
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Abstract
The invention relates to the technical field of laser welding, and provides a splash suppression method and device in an ultra-high power laser welding process. According to the method and the device for suppressing the splashing in the ultra-high power laser welding process, the suppression nozzle is arranged, the liquid column and the splashing are extracted based on the monitoring image, and the suppression nozzle is used for suppressing the liquid column and the splashing according to the extracted characteristics, so that the splashing formed outside a welding line is greatly reduced, the problem of suppressing the splashing in the ultra-high power laser welding of a medium plate of a large-sized complex component is solved, the non-splashing welding is facilitated, and a reliable means is provided for guaranteeing the welding quality.
Description
Technical Field
The invention relates to the technical field of laser welding, in particular to a splash suppression method and device in an ultra-high power laser welding process.
Background
The laser welding technology is widely applied to the industries of aerospace, rail transit, marine equipment, medical treatment and the like, and the application range is continuously widened. The quality requirements of the industry on laser welding are higher and higher, and the laser welding is extremely easy to generate welding spatter under the conditions of ultra-high power, high speed, high-reflection material welding and the like. The splash defect in the laser welding process is effectively controlled, and the method has important significance in improving the laser welding quality and widening the application field. When the ultra-high power optical fiber is welded by laser, the energy density can reach 108W/cm 2, and the metal material is evaporated extremely severely in the welding process; under the strong recoil pressure of the metal vapor, the molten metal in the molten pool is pushed away instantly, so that a superfine bar spoon hole is formed; the flow rule of the molten metal is changed, and a high liquid column is easy to form at the opening of the small hole; the shearing force of high-temperature (up to 6000K) and high-speed (up to 500 m/s) metal vapor passing through the ultra-slender small holes can easily separate molten metal from the top end of the liquid column to form splashes. The formation of a large amount of splashes reduces molten metal, resulting in weld defects such as unfilled weld seams, undercut and the like; in addition, the splash can pollute the workpiece, and the splash is removed by an extra process, so that the manufacturing cost is increased, and the production efficiency is reduced. Therefore, how to suppress spatter becomes one of the main challenges limiting the application of ultra-high power fiber laser welding technology.
In recent years, tunable annular spot, beam wobble, blue and green welding techniques have been proposed and used for spatter suppression. Research shows that the blue-green light has high processing cost and low laser power, is commonly used for processing a thin plate in 2mm, and can be used for adjusting annular light spots and beam swing welding when the laser power is kilowatt level, and after optimizing the technological parameters, the stability of the welding process is improved and the splashing is reduced. The process can reduce splashing, but the welding process is easily influenced by factors such as welding environment, assembling state and the like, and the splashing generated by uncertain factors in the welding process can not be inhibited. And the laser power of the ultra-high power laser welding breaks through the level of ten watts, the welding process is extremely complex, and the welding process is more easily unstable to cause a large amount of splash formation. In addition to optimizing laser welding process parameters, it is desirable to study the splash active suppression method.
Disclosure of Invention
In view of the above, the invention provides a method and a device for suppressing the splashing in the ultra-high power laser welding process, which are used for extracting the characteristics of a liquid column and the splashing based on a monitoring image by arranging a suppressing nozzle, and suppressing the liquid column and the splashing by the suppressing nozzle according to the extracted characteristics, so that the splashing formed outside a welding line is greatly reduced, the problem of suppressing the splashing in the ultra-high power laser welding of a medium plate of a large complex component is solved, the non-splashing welding is realized, and a reliable means is provided for guaranteeing the welding quality.
The technical scheme of the invention is realized as follows:
in one aspect, the present invention provides a splash suppression method in an ultra-high power laser welding process, which is implemented based on a splash suppression system, wherein the splash suppression system includes a plurality of suppression nozzles, a first camera and a second camera, the plurality of suppression nozzles are arranged at two sides of a welding position in a mirror image manner, the plurality of suppression nozzles are used for suppressing a liquid column and splash, the first camera is arranged horizontally, the second camera is arranged obliquely, and the first camera and the second camera are opposite to the welding position, and the splash suppression method includes the following steps:
S1, acquiring a molten metal liquid column monitoring image in a welding process by a first camera, and acquiring a welding area monitoring image by a second camera;
S2, extracting key parameters of a liquid column, a small hole, a molten pool and splashing according to the liquid column monitoring image of the molten metal and the welding area monitoring image;
s3, fitting to obtain a laser motion path according to key parameters of the small hole and the molten pool;
And S4, controlling the suppression nozzle to spray the protective gas according to the key parameters of the liquid column, suppressing the height of the liquid column, and regulating and controlling the protective gas flow of the suppression nozzle according to the key parameters of the splashing, so that the splashing falls into a laser motion path or a molten pool.
On the basis of the above technical solution, preferably, before the step S1, determining a laser welding speed, determining a position of the liquid column on the small hole according to the laser welding speed, and adjusting positions of the plurality of suppression nozzles by the position of the liquid column on the small hole, so that one part of the suppression nozzles serve as liquid column height suppression, and the other part of the suppression nozzles serve as splash suppression.
On the basis of the above technical solution, preferably, the first camera acquiring the monitoring image of the molten metal column includes the following substeps:
S11, shooting a liquid column in the welding process from the horizontal direction by a first camera to obtain an image to be processed;
s12, overlapping and fusing the image to be processed and the mask image to obtain a fused image;
S13, binarizing the fusion image, and adjusting to obtain a molten metal liquid column monitoring image.
On the basis of the above technical solution, preferably, the step S2 includes the following substeps:
s21, monitoring key parameters of the image extraction liquid column according to the molten metal liquid column;
s22, establishing an image segmentation model, performing semantic segmentation on the welding area monitoring image, and respectively obtaining monitoring images of pinholes, molten pools and splashes;
s23, extracting target contours from the monitoring images of the small holes, the molten pool and the splashing, and respectively obtaining key parameters of the small holes, the molten pool and the splashing.
On the basis of the technical scheme, preferably, the key parameters of the liquid column comprise liquid column height and angle, the key parameters of the small holes comprise width and length, the key parameters of the molten pool comprise molten pool width and length, and the key parameters of splashing comprise splashing center coordinates.
Further preferably, the step S3 includes the following substeps:
s31, determining a molten pool center coordinate at the corresponding width of the molten pool and a small hole center coordinate at the corresponding width of the small hole according to the width of the molten pool and the width of the small hole;
s32, extracting a plurality of molten pool center coordinates at equal intervals in the length direction of a molten pool, and extracting a plurality of small hole center coordinates at equal intervals in the length direction of a small hole;
And S33, fitting the center coordinates of the multiple molten pools and the center coordinates of the multiple small holes to obtain a laser motion path.
On the basis of the above technical solution, preferably, before the step S4, the method further includes setting a liquid column threshold, judging whether a key parameter of the liquid column reaches the liquid column threshold, and if so, controlling the suppression nozzle to spray the protective gas according to the key parameter of the liquid column to suppress the height of the liquid column.
On the other hand, the invention provides a splash suppression device in the ultra-high power laser welding process, which is used for realizing the splash suppression method, and comprises a plurality of suppression nozzles, a first camera and a second camera, wherein the suppression nozzles are arranged on two sides of a welding position in a mirror image mode, the suppression nozzles are used for suppressing a liquid column and splash, the first camera is horizontally arranged, the second camera is obliquely arranged, and the first camera and the second camera are opposite to the welding position.
On the basis of the technical scheme, the welding machine further comprises a demisting nozzle, wherein the demisting nozzle is arranged on the outer side of the welding position and is used for spraying protective gas to remove metal atomized gas in the welding process.
On the basis of the technical scheme, the camera comprises a first camera, a second camera, a plurality of suppression nozzles, a mounting bracket and a control device, wherein the mounting bracket is relatively fixed with the first camera and the second camera, the suppression nozzles are all arranged on the mounting bracket, and the relative positions and the relative angles of the suppression nozzles and the small holes can be adjusted through the mounting bracket.
Compared with the prior art, the splash suppression method and device for the ultra-high power laser welding process have the following beneficial effects:
(1) By arranging two industrial cameras, the characteristics of small holes, a molten pool, a liquid column and splashing can be obtained in the welding process, wherein a first camera acquires key parameters of the liquid column and provides data support for the height inhibition of the liquid column, so that the height inhibition of the liquid column is realized, the formation of large-size splashing is greatly reduced, the key parameters of the small holes, the molten pool and the splashing acquired by a second camera which are obliquely arranged can provide data support for inhibiting the formed splashing, so that the splashing falls in the welding direction or the molten pool, the splashing is reused, the splashing formed outside a welding seam is greatly reduced, the problem of the ultra-high power laser welding splashing inhibition of a medium plate of a large complex component is solved, the non-splashing welding is realized, and a reliable means is provided for guaranteeing the welding quality;
(2) The suppression nozzles of the multiple images are arranged, the positions and angles of the suppression nozzles can be well determined through the welding speed, and then the obtained key parameters of liquid column, molten pool, small hole and splashing are combined, so that the formation of the splashing is accurately regulated and controlled, the welding quality is ensured, the suppression nozzles can be used in other forms of welding, and even combined with special processes (adjustable annular light spots, light beam swinging and the like), the splashing is effectively suppressed, and the ultra-high power splashing-free welding is realized;
(3) The image processing and feature extraction method ensures the real-time performance of monitoring, and in addition, the monitoring result of the welding process can be used for post-welding quality assessment, such as weld pool and small hole feature prediction, and data is provided for retrospective welding process;
(4) The defogging nozzle that sets up can effectively get rid of the metal vapor that forms when the welding in the welding process, reduces the interference that metal vapor formed when image acquisition, provides accurate data for the shielding gas regulation and control to do benefit to further regulation and control shielding gas parameter, metal vapor influences the light beam quality, consequently adopts shielding gas to blow off metal vapor, reduces the influence of light beam quality to welding process stability, further reduces the formation of splashing.
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In order to more clearly illustrate the embodiments of the invention or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, it being obvious that the drawings in the following description are only some embodiments of the invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic diagram of the steps of the spatter suppressing method in the ultra-high power laser welding process of the present invention;
FIG. 2 is a schematic view of the liquid column of the splash suppression device at the front end of the small hole in the ultra-high power laser welding process;
FIG. 3 is a schematic view of the liquid column of the splash suppression device at the rear end of the small hole in the ultra-high power laser welding process;
FIG. 4 is a side view of the welding direction of the spatter suppressing device of the ultra high power laser welding process of the present invention;
FIG. 5 is an exemplary view of an image to be processed of the spatter suppressing method of the ultra-high power laser welding process of the present invention;
FIG. 6 is an exemplary view of a weld area monitoring image of the spatter suppression method of the ultra-high power laser welding process of the present invention;
FIG. 7 is a schematic diagram of a fused image acquisition step of the spatter suppression method of the ultra-high power laser welding process of the present invention;
FIG. 8 is a schematic view of a step of acquiring a molten metal column monitoring image of the spatter suppressing method in the ultra-high power laser welding process of the present invention;
Fig. 9 is a diagram showing an example of the effect of suppressing the molten column of the spatter suppressing method in the ultra-high power laser welding process of the present invention.
Detailed Description
The following description of the embodiments of the present invention will clearly and fully describe the technical aspects of the embodiments of the present invention, 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 present invention without making any inventive effort, are intended to fall within the scope of the present invention.
The laser welding is extremely easy to generate welding spatter under the conditions of ultra-high power, high speed, high-reflection material welding and the like. At present, special technology and parameter optimization are often adopted to reduce splashing, and the effect is good when kilowatt level low power is achieved, but the welding process of the kilowatt level ultrahigh power laser is more complex, and the stability of the welding process is more susceptible to the influence of uncertain factors to cause splashing. The formation of spatter can affect the quality and the processing efficiency of a welding line, and the active inhibition method of the spatter needs to be researched, so that the welding quality and the welding efficiency are ensured.
In the research process, according to the actual welding situation, the large-size splash is separated from the top end of the molten metal liquid column in the laser welding process, the height and the angle of the liquid column are directly related to the number and the movement direction of the splash, and the height wall surface of the molten metal liquid column is regulated to reach the critical condition of splash formation or the generated large-size splash is returned to the welding process (remelted or returned to a molten pool) so as to realize the active suppression of the splash.
On the basis, the invention provides a corresponding splash suppression method to suppress the liquid column to greatly reduce the formation of large-size splashes, and actively adjust the formed splashes to make the formed splashes participate in the welding process again.
As shown in fig. 1 to 4, the splash suppression method in the ultra-high power laser welding process of the present invention is implemented based on a splash suppression system, the splash suppression system includes a plurality of suppression nozzles 3, a first camera 1 and a second camera 2, the plurality of suppression nozzles 3 are mirror-image-arranged at two sides of a welding position, the plurality of suppression nozzles 3 are used for suppressing liquid column and splash, the first camera 1 is horizontally arranged, the second camera 2 is obliquely arranged, and the first camera 1 and the second camera 2 are opposite to the welding position, and specifically, the splash suppression method includes steps S1 to S4.
Step S1: a molten metal column monitoring image during welding is acquired by the first camera 1, and a welding area monitoring image is acquired by the second camera 2.
As shown in fig. 2-3, before this step, it is necessary to determine the morphological characteristics of the liquid column and further determine how to suppress the liquid column, and experiments prove that, during the laser welding process, the position of the molten metal column is not greatly related to the thickness of the welded plate, but is closely related to the welding speed, the molten metal column is usually located at the front end of the opening of the welding aperture and the rear end of the opening of the welding aperture, wherein the front and rear directions are divided in the laser welding direction, especially during the low-speed welding, the molten metal column is located at the front end of the aperture, and during the high-speed welding, the molten metal column is located at the rear end of the aperture, for example, the welding speed is about 3m/min, and the molten metal column is located at the rear end of the aperture.
Before plate welding, the welding speed to be selected can be determined according to the welding environment and the actual situation, then the position of the liquid column on the welding small hole during welding is determined according to the welding speed, and then the position and the angle of each inhibition nozzle 3 are adjusted according to the position of the molten liquid column on the small hole, and the positions of the inhibition nozzles 3 are related to the positions of the liquid column, and the injection angle of the shielding gas of the inhibition nozzles 3 is related to the height of the liquid column.
The specific position and angle of the suppression nozzle 3 can be obtained by calibrating with a substitute, or the position and angle of each suppression nozzle 3 to be adjusted under a certain welding speed can be determined in advance through experiments, taking the position and angle of the suppression nozzle 3 obtained by calibrating with the substitute as an example, firstly determining the average stable height of the liquid column and the position of the liquid column on the X-Y horizontal plane, simulating the size and position of the liquid column by using the plasticine, then setting the calibrating laser at the front end of the suppression nozzle 3, adjusting the position of the protective gas nozzle, ensuring that the laser irradiates on the top of the plasticine, and completing the position calibration of the suppression nozzle 3.
For ease of understanding, in the present embodiment, the welding direction is defined as the X axis, the direction perpendicular to the X axis in the horizontal plane is defined as the Y axis, and the direction perpendicular to the horizontal plane is defined as the Y axis.
In the case of the spray suppression nozzle 3 for performing spray suppression, it is known that the spray formed on the small hole moves in a direction away from the center of the small hole, and the large-sized spray and most of the small-sized spray are formed by being separated from the tip of the liquid column, so that the spray suppression nozzle 3 for suppressing spray can be directly provided on the movement path of spray.
In the present embodiment, the number of the suppression nozzles 3 provided is four, two of which are symmetrically provided on both sides of the welding path, two of which are opposite to the liquid column, serving as a height suppression of the liquid column, and the other two of which are offset toward the direction in which the liquid column forms spatter, so as to suppress the movement of the spatter.
The preparation work before welding is finished in the mode, and after the splash suppression system is debugged, the welding operation can be performed.
The first camera 1 shoots the side face of the liquid column from the horizontal position during welding so as to obtain a monitoring image of the liquid column of molten metal, and the method specifically comprises the steps S11-S13.
Step S11: the liquid column during welding is photographed from the horizontal direction by the first camera 1, and an image to be processed is obtained.
As shown in fig. 5, the first camera 1 and the second camera 2 are both high-speed industrial cameras, and perform high-frequency continuous shooting in the welding process, and the first camera 1 can obtain a to-be-processed image with a complete melt column through horizontal shooting, and it should be noted that the obtained to-be-processed image is a gray image, and specifically, the to-be-processed image can be realized by installing an optical filter on a camera lens.
Step S12: and superposing and fusing the image to be processed and the mask image to obtain a fused image.
As shown in fig. 7, in this embodiment, a liquid column extraction method based on mask fusion is provided, specifically, two masks, namely a first mask and a second mask, are provided, specifically, the first mask is provided according to the position of the liquid column, two white areas with the width of 2 pixels and the height of 15 pixels are provided on the first mask, the pixel value in the white area is 1, and the contact between the liquid column and the image edge is ensured; the second mask is provided with a white area with the width of 20 pixels and the length of the same as that of the image on the upper side, the left side and the right side respectively, the pixel value in the area is 1, two sections of areas with the width of 2 pixels are arranged on the lower side of the image, the rightmost point of the left lower area is smaller than the leftmost point of the left long strip area in the first mask by 5 pixels, the leftmost point of the right lower area is larger than the rightmost point of the right long strip area in the first mask, the targets, especially plates, of which the edges of the image are contacted on the upper, lower, left and right sides of the image can be removed by arranging the second mask, only the liquid column is reserved, in addition, the image to be processed and the mask image with the same size are overlapped and fused to obtain a fusion image, and the preprocessed image is the image to be processed.
Step S13: and carrying out binarization treatment on the fusion image, and adjusting to obtain a molten metal liquid column monitoring image.
As shown in fig. 8, the segmentation threshold is set according to the brightness characteristics of the liquid column to perform binarization processing on the fused image, then the area contacted with the image edge is reserved, only the liquid column is contacted with the image edge through mask processing, therefore, the liquid column area is rapidly obtained, finally, the liquid column edge burr is removed through morphological open operation processing fine adjustment, such as a strip area introduced during fusion with the mask one, an accurate molten metal liquid column monitoring image is obtained, and the finally obtained image in the figure is the molten metal liquid column monitoring image.
As shown in fig. 6, the first camera 1 acquires the molten metal column monitoring image and the second camera 2 simultaneously shoots to acquire the welding area monitoring image, and since the second camera 2 shoots obliquely, an image having a molten pool, pinholes and splashes can be acquired.
Step S2: and extracting key parameters of the liquid column, the small holes, the molten pool and the splashing according to the liquid column monitoring image of the molten metal and the welding area monitoring image.
In the present embodiment, the key parameters of the liquid column are obtained from the molten metal liquid column monitoring image, the key parameters of the keyhole, the molten pool and the splash are obtained from the welding area detection image, and specifically steps S21 to S23 are included.
Step S21: and monitoring key parameters of the image extraction liquid column according to the molten metal liquid column.
According to the morphological characteristics of the molten metal column in the molten metal column monitoring image, key parameters of the molten metal column are extracted, wherein the key parameters comprise specific area, perimeter, height, width and angle characteristics, the characteristics can determine whether the molten metal column can form large-size splashing or not, and meanwhile, whether the height inhibition of the liquid column, particularly the height and angle characteristics of the liquid column, are required to be carried out or not can be determined, and the method can be used as a main judging factor of whether the liquid column reaches critical conditions of splashing generation or not, namely morphological characteristic limit values.
Specifically, for the area of the liquid column, the total number of pixel points with all pixel values of 1 in the liquid column extraction image can be obtained, the liquid column outline is firstly extracted when the perimeter is obtained, then the total amount of all pixel points on the liquid column outline is calculated, the liquid column outline image is coordinated to obtain the coordinates of the uppermost point, the leftmost point, the rightmost point and the lowest center point of the contact line of the liquid column and the image edge, the liquid column width is obtained by subtracting the leftmost point abscissa from the rightmost point abscissa, the liquid column height is obtained by subtracting the lowest center point ordinate from the highest point ordinate, the deviation value is obtained by subtracting the lowest center point abscissa from the highest point abscissa, and finally the liquid column angle is calculated by the deviation and the height, so that the characteristics of the liquid column such as height, width, angle and the like can be obtained.
Step S22: establishing an image segmentation model, carrying out semantic segmentation on the welding area monitoring image, and respectively obtaining monitoring images of pinholes, molten pools and splashes.
Because the features of the small hole, the molten pool and the splash are required to be acquired respectively in the welding area monitoring image, in order to separate the small hole, the molten pool and the splash from the welding area monitoring image, an image segmentation model is introduced in the embodiment to be used for establishing different image layers, so that the small hole, the molten pool and the splash are segmented onto the different image layers respectively, and a single monitoring image corresponding to the small hole, the molten pool and the splash is obtained.
Specifically, the image segmentation model can adopt a lightweight semantic segmentation model to carry out semantic segmentation operation of the welding region detection image, before the model is used, labelme software is required to be adopted to label 200 joint region monitoring images, then transfer learning is adopted to construct the semantic segmentation model, the transfer learning can reduce training data, improve the model construction speed and ensure the model precision, and in addition, the lightweight model ensures that the monitoring images are rapidly processed.
The lightweight semantic segmentation model is constructed based on Unet deep learning models and DANet attention mechanisms, takes a VGG16 model as a main frame, adopts symmetrical encoder and decoder structures, and consists of 10 units, wherein the model is composed of 23 convolution layers, 4 downsampling layers, 4 upsampling layers, 4 fusion layers and 4 DANet attention mechanism modules, the left half part of the model comprises 5 units, the left half part is used for extracting high-dimensional features by gradually reducing the space size of an input image, the number of convolution kernels in each unit is 64, 128, 256, 512 and 1024, the convolution kernel size is 3×3, the maximum pooling is adopted for downsampling, the kernel size is 2×2, the step length is 2, the 5 th unit is the end of downsampling and the beginning of upsampling, and the right half part of the network is provided with 4 units, so that the high-dimensional features are gradually restored to the original resolution; the 9 th and 1 st units, the 8 th and 2 nd units, the 7 th and 3 rd units and the 6 th and 4 th units are respectively symmetrical, and the corresponding feature patterns have the same size; each unit adopts a 2 multiplied by 2 deconvolution up-sampling recovery feature map, and features subjected to the 10 th unit feature reinforcement treatment are combined with shallow features of the corresponding units through a series method, so that details of the feature map are better recovered, and the corresponding space information dimension is ensured to be unchanged; the final layer of the 9 th unit adopts 1x1 convolution operation to map the characteristic vector of each 64 components to 2 categories required, and the model can predict an input image with any size and output a semantic segmentation image with the same size.
Step S23: and extracting target contours from the monitoring images of the small holes, the molten pool and the splashing, and respectively obtaining key parameters of the small holes, the molten pool and the splashing.
After the monitoring images of the small hole, the molten pool and the splashing are segmented, the target outline in the corresponding monitoring image is extracted, the image is coordinated, and morphological characteristics needing to be extracted, such as a small hole center coordinate (laser), a molten pool multi-position width characteristic, a molten pool length and a splashing center coordinate, are calculated according to the limit coordinates of each direction of the monitoring object.
Step S3: and fitting according to key parameters of the small hole and the molten pool to obtain a laser motion path.
In this embodiment, a straight line is first fitted through the small hole and the critical parameters of the molten pool, and in a certain area near the straight line, the straight line and the welding area near the straight line belong to the welding area, and the straight line and the welding area near the straight line belong to the laser motion path, that is, the straight line with a certain width, and the width is smaller than the maximum width of the molten pool, and specifically includes steps S31-S33.
Step S31: and determining the center coordinates of the molten pool at the corresponding width of the molten pool and the center coordinates of the small holes at the corresponding width of the small holes according to the width of the molten pool and the width of the small holes.
Because the whole molten pool is in a drop-like shape, one end of the molten pool is round, the other end of the molten pool is sharp, and the molten pool is not completely symmetrical, a certain width is required to be selected in the length direction, namely the X-axis direction, so that the center coordinate of the molten pool is calculated, the preparation is carried out for obtaining a fitting straight line subsequently, and the center coordinate of the small hole at the corresponding width position of the small hole is obtained in the same way.
Step S32: and extracting a plurality of molten pool center coordinates at equal intervals in the length direction of the molten pool, and extracting a plurality of small hole center coordinates at equal intervals in the length direction of the small hole.
In this embodiment, the width of the molten pool at multiple positions is based on the front end of the molten pool, each time a set distance (for example, 50 pixels) is increased, the width of the molten pool at the position is extracted, then the width of the molten pool at the equal distance of 50/100/150 is extracted, the ordinate of the contour point of the molten pool when the width of the molten pool is calculated, and the center of the ordinate is calculated, so that a plurality of center coordinates of the molten pool in the length direction of the molten pool are obtained, the length of the molten pool is closely related to the laser welding speed, and therefore, a fixed amount of the extracted center coordinates of the molten pool does not exist.
Correspondingly, the small holes also adopt the same mode as the molten pool to extract the center coordinates of a plurality of small holes, and as the small holes are smaller relative to the molten pool and are closer to the arc end part of the molten pool, the small holes can extract the width once every 20 pixels and obtain the corresponding center coordinates of the small holes, and the small hole width extraction direction is required to be consistent with the molten pool width extraction direction, namely the X-axis direction.
Step S33: fitting the center coordinates of the molten pools with the center coordinates of the small holes to obtain a laser motion path.
Firstly, fitting a plurality of molten pool center coordinates and a plurality of small hole center coordinates to obtain a middle straight line, respectively arranging edge straight lines on two sides of the middle straight line, wherein the edge straight lines are parallel to the middle straight line and are positioned on the same horizontal plane, the vertical distance from the edge straight line to the middle straight line is not more than one third of the maximum width of the molten pool, and the part between the two edge straight lines, which exceeds the molten pool along the laser movement route, is the laser movement route, that is, the width of the laser movement route is not more than two thirds of the maximum width of the molten pool.
Step S4: according to the key parameters of the liquid column, the control and inhibition nozzle 3 sprays protective gas to inhibit the height of the liquid column, and according to the key parameters of splashing, the protective gas flow of the inhibition nozzle 3 is regulated and controlled to enable the splashing to fall into a laser movement path or a molten pool.
Before the step, a liquid column threshold is set according to morphological characteristic limit values of the liquid column for generating large-size splashing, the threshold can comprise characteristics such as angle and height of the liquid column, the liquid column threshold is specifically set before the liquid column for generating the large-size splashing, and the liquid column threshold can be selectively set according to actual welding conditions.
When the key parameters of the liquid column reach the liquid column threshold, the two inhibition spray heads calibrated and aligned with the liquid column can spray the protective gas to push down the height of the liquid column, so that the height of the liquid column is regulated and controlled, the probability of large-size splash formation is reduced, and when the height of the liquid column is regulated and controlled to be maintained in a certain range, the flow of the protective gas can be regulated through the change of the height of the liquid column.
Correspondingly, a suppression threshold is also required to be set, wherein the suppression threshold is the height reached by the liquid column when the liquid column is suppressed by the protective gas, and the protective gas flow is increased when the height is exceeded, otherwise, the protective gas flow is reduced, so that the liquid column height is suppressed to be close to the height.
When the formed spatter flies out, because the two sides of the welding direction are provided with the suppression spray heads, the suppression spray heads blow the spatter back to the molten pool on the live laser movement path according to the spatter center coordinates of the spatter on the image, and the fact that the spatter which is blown back to the molten pool and is re-participated in welding needs to be dropped in the area which is centered in the molten pool and has the same width as the laser movement path, and the spatter which is blown to the laser movement path is re-melted in the follow-up laser welding movement process, so that the welding quality is improved by suppressing the spatter through the adjustment of the liquid column and the spatter in the ultra-high power welding operation process.
After the splash is formed, parabolic motion is performed, a splash point can be calculated according to the splash speed and angle, the protective air flow of the suppression spray head is regulated, and the splash position is adjusted.
As shown in fig. 9, a total of 24 images with numbers 1177-1200 are selected, in the image with number 1197, the key parameters of the liquid column reach the liquid column threshold value, the height of the liquid column is suppressed from the image with number 1198, the suppression effect is obvious in two subsequent continuous images, meanwhile, in fig. 9, the continuous change relation of the liquid column area, the perimeter, the width, the height and the deviation is given, and it can be seen that when the liquid column is suppressed, each characteristic of the liquid column is obviously reduced, and the deviation is the difference of the highest point abscissa minus the lowest center point abscissa.
As shown in fig. 2-4, the splash suppression device in the ultra-high power laser welding process of the present invention is used for implementing the splash suppression method, and includes a plurality of suppression nozzles 3, a first camera 1 and a second camera 2, wherein the plurality of suppression nozzles 3 are arranged at two sides of a welding position in a mirror image manner, the plurality of suppression nozzles 3 are used for suppressing liquid columns and splashes, the first camera 1 is horizontally arranged, the second camera 2 is obliquely arranged, and the first camera 1 and the second camera 2 are opposite to the welding position, in this embodiment, in order to implement that each suppression nozzle 3 is not completely fixed relative to the camera according to a welding speed, but is arranged to be adjustable along a welding direction.
The splash suppression system comprises a splash suppression device and is provided with a server in a matching way, data collected by the first camera 1 and the second camera 2 are sent into the server to be analyzed and processed, flow adjustment data of the suppression nozzle 3 are output, and the inclination angle of the second camera 2 can be set to be forty-five degrees.
As a preferred embodiment, the splash suppression device is further provided with a demisting nozzle 4, the demisting nozzle 4 is arranged on the outer side of the welding position, and the demisting nozzle 4 is used for spraying protective gas so as to remove metal atomized gas in the welding process.
Correspondingly, four suppression nozzles 3 are arranged, five nozzles are arranged in total in addition to the demisting nozzles 4, five nozzle switch triggering devices and five nozzle position correction lasers are also required to be arranged in the splash suppression system, the four suppression nozzles 3 for regulating and controlling the height of the liquid column are arranged at two sides of the welding direction in a mirror image mode, the demisting nozzles 4 for blowing off metal steam are arranged at the center position of the direct forefront end, and the triggering devices are electrically connected with the suppression nozzles 3 and used for rapidly controlling the switch and the flow of the shielding gas.
When the liquid column is in a normal range, the splash suppression device only opens the demisting nozzle 4, when the liquid column is gradually increased, the corresponding mirror image suppression spray head is gradually opened, the protective air flow is dynamically adjusted along with the characteristics such as the liquid column height, the liquid column height is suppressed to reach a set threshold value, and the splash formation is prevented.
In this embodiment, a mounting bracket 5 is further provided, a plurality of the suppression nozzles 3 are all disposed on the mounting bracket 5, the relative positions and relative angles of the suppression nozzles 3 and the small holes can be adjusted by the mounting bracket 5, the mounting bracket 5 can be set to be U-shaped and is mounted above the welding horizontal plane, the suppression nozzles 3 are fixed on the mounting bracket 5 by the adjustable bracket, and the positions and the angles of the suppression nozzles 3 are adjusted before welding.
In addition, in the splash suppression system, a protective gas nozzle aligned with the tail of the molten pool is also arranged, and the protective gas nozzle blows out protective gas to prevent oxidation before solidification of the welding seam so as to improve the quality of the welding seam.
The foregoing description of the preferred embodiments of the invention is not intended to be limiting, but rather is intended to cover all modifications, equivalents, alternatives, and improvements that fall within the spirit and scope of the invention.
Claims (10)
1. The splash suppression method for the ultra-high power laser welding process is characterized by being realized based on a splash suppression system, wherein the splash suppression system comprises a plurality of suppression nozzles (3), a first camera (1) and a second camera (2), the suppression nozzles (3) are arranged on two sides of a welding position in a mirror image mode, the suppression nozzles (3) are used for suppressing liquid columns and splashing, the first camera (1) is horizontally arranged, the second camera (2) is obliquely arranged, and the first camera (1) and the second camera (2) are opposite to the welding position, and the splash suppression method comprises the following steps:
s1, acquiring a molten metal liquid column monitoring image in a welding process by a first camera (1), and acquiring a welding area monitoring image by a second camera (2);
S2, extracting key parameters of a liquid column, a small hole, a molten pool and splashing according to the liquid column monitoring image of the molten metal and the welding area monitoring image;
s3, fitting to obtain a laser motion path according to key parameters of the small hole and the molten pool;
s4, controlling the suppression nozzle (3) to spray protection gas according to key parameters of the liquid column, suppressing the height of the liquid column, and regulating and controlling the protection gas flow of the suppression nozzle (3) according to key parameters of splashing, so that the splashing falls into a laser motion path or a molten pool.
2. The ultra-high power laser welding process spatter suppressing method according to claim 1, further comprising, before said S1, determining a laser welding speed, and determining a position of the liquid column on the hole according to the laser welding speed, and performing position adjustment of the plurality of suppressing nozzles (3) by the position of the liquid column on the hole so that a part of the suppressing nozzles (3) functions as the liquid column height suppression and another part of the suppressing nozzles (3) functions as the spatter suppression.
3. The ultra-high power laser welding process spatter suppression method according to claim 1, wherein the first camera (1) acquires a molten metal column monitoring image comprising the sub-steps of:
s11, shooting a liquid column in the welding process from the horizontal direction by a first camera (1) to obtain an image to be processed;
s12, overlapping and fusing the image to be processed and the mask image to obtain a fused image;
S13, binarizing the fusion image, and adjusting to obtain a molten metal liquid column monitoring image.
4. The ultra-high power laser welding process spatter suppressing method according to claim 1, wherein said step S2 comprises the sub-steps of:
s21, monitoring key parameters of the image extraction liquid column according to the molten metal liquid column;
s22, establishing an image segmentation model, performing semantic segmentation on the welding area monitoring image, and respectively obtaining monitoring images of pinholes, molten pools and splashes;
s23, extracting target contours from the monitoring images of the small holes, the molten pool and the splashing, and respectively obtaining key parameters of the small holes, the molten pool and the splashing.
5. The ultra-high power laser welding process spatter suppression method of claim 1 wherein said critical parameters of the liquid column include liquid column height and angle, said critical parameters of the orifice include width and length, said critical parameters of the molten pool include molten pool width and length, and said critical parameters of spatter include spatter center coordinates.
6. The ultra-high power laser welding process spatter suppressing method according to claim 5, wherein said step S3 comprises the sub-steps of:
s31, determining a molten pool center coordinate at the corresponding width of the molten pool and a small hole center coordinate at the corresponding width of the small hole according to the width of the molten pool and the width of the small hole;
s32, extracting a plurality of molten pool center coordinates at equal intervals in the length direction of a molten pool, and extracting a plurality of small hole center coordinates at equal intervals in the length direction of a small hole;
And S33, fitting the center coordinates of the multiple molten pools and the center coordinates of the multiple small holes to obtain a laser motion path.
7. The method for suppressing the splashing of the ultra-high power laser welding process according to claim 1, wherein the method further comprises the steps of setting a liquid column threshold before the step S4, judging whether the key parameter of the liquid column reaches the liquid column threshold, and if so, controlling the suppressing nozzle (3) to spray the protective gas according to the key parameter of the liquid column to suppress the height of the liquid column.
8. The splash suppression device for the ultra-high power laser welding process is characterized by being used for realizing the splash suppression method according to any one of claims 1-7, and comprises a plurality of suppression nozzles (3), a first camera (1) and a second camera (2), wherein a plurality of the suppression nozzles (3) are arranged on two sides of a welding position in a mirror image mode, a plurality of the suppression nozzles (3) are used for suppressing liquid columns and splash, the first camera (1) is horizontally arranged, the second camera (2) is obliquely arranged, and the first camera (1) and the second camera (2) are opposite to the welding position.
9. The ultra-high power laser welding process spatter suppressing device according to claim 8, further comprising a defogging nozzle (4), said defogging nozzle (4) being provided at an outer side of the welding position, said defogging nozzle (4) being for ejecting a shielding gas to remove a metal atomized gas during the welding process.
10. The device for suppressing the splashing of the ultra-high power laser welding process according to claim 8, further comprising a mounting bracket (5), wherein the mounting bracket (5) is relatively fixed with the first camera (1) and the second camera (2), a plurality of suppressing nozzles (3) are arranged on the mounting bracket (5), and the relative positions and the relative angles of the suppressing nozzles (3) and the small holes can be adjusted through the mounting bracket (5).
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN201143602Y (en) * | 2007-11-30 | 2008-11-05 | 深圳市大族激光科技股份有限公司 | Laser welder head |
| CN113059266A (en) * | 2021-05-19 | 2021-07-02 | 华工法利莱切焊系统工程有限公司 | Laser welding air knife assembly and laser welding equipment |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| DE102014203576A1 (en) * | 2014-02-27 | 2015-08-27 | Trumpf Laser- Und Systemtechnik Gmbh | Laser processing head with a crossjet nozzle close to the workpiece |
| DE102019212403B4 (en) * | 2019-08-20 | 2022-04-07 | Trumpf Laser- Und Systemtechnik Gmbh | Method for controlling at least one processing parameter based on at least one spatter feature and associated processing machine and computer program product |
| DE102021212120A1 (en) * | 2021-10-27 | 2023-04-27 | Robert Bosch Gesellschaft mit beschränkter Haftung | Method for quantifying and/or qualifying melt spatter, laser processing device, computer program and machine-readable storage medium |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN201143602Y (en) * | 2007-11-30 | 2008-11-05 | 深圳市大族激光科技股份有限公司 | Laser welder head |
| CN113059266A (en) * | 2021-05-19 | 2021-07-02 | 华工法利莱切焊系统工程有限公司 | Laser welding air knife assembly and laser welding equipment |
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