CN108941939B - Closed-loop laser processing quality control method based on molten pool splash detection - Google Patents
Closed-loop laser processing quality control method based on molten pool splash detection Download PDFInfo
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- CN108941939B CN108941939B CN201810763091.2A CN201810763091A CN108941939B CN 108941939 B CN108941939 B CN 108941939B CN 201810763091 A CN201810763091 A CN 201810763091A CN 108941939 B CN108941939 B CN 108941939B
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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
- B23K26/70—Auxiliary operations or equipment
- B23K26/702—Auxiliary equipment
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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
- B23K26/14—Working by laser beam, e.g. welding, cutting or boring using a fluid stream, e.g. a jet of gas, in conjunction with the laser beam; Nozzles therefor
- B23K26/146—Working by laser beam, e.g. welding, cutting or boring using a fluid stream, e.g. a jet of gas, in conjunction with the laser beam; Nozzles therefor the fluid stream containing a liquid
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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
- B23K26/16—Removal of by-products, e.g. particles or vapours produced during treatment of a workpiece
Abstract
The invention provides a closed-loop laser processing quality control method based on molten pool splash detection, which comprises the following steps: (1) clamping, and setting a laser processing path and initial technological parameters; (2) starting an internal water cooling system of a splash baffle on the laser processing head and a circulating water cooling system of the laser processing head; (3) outputting laser beams, outputting synchronous powder/wire feeding and air feeding, starting the pre-programmed relative motion of a laser processing head and a workpiece, and performing laser processing; (4) in the laser processing process, obtaining characteristic data of the current splash; (5) obtaining characteristic data of the current splashed objects at each monitoring point through the current panoramic infrared temperature field image; (6) repeatedly executing the step (5) to complete the current processing task; (7) reference characteristic data is obtained. The invention makes the real-time analysis of the laser processing process quality feasible in the laser processing process, and realizes the complete closed-loop control of the processing quality by combining the online real-time adjustment of the laser processing process parameters.
Description
The application is a divisional application with the application number of 201710565596.3, the application date of 2017-07-12 and the name of closed-loop laser processing quality control device and method based on molten pool splash detection.
Technical Field
The invention belongs to the field of laser processing, and particularly relates to a closed-loop laser processing quality control device and method based on molten pool splash detection.
Background
The laser processing technology is a technology for cutting, welding, cladding, surface treatment, drilling, micromachining and the like of materials (including metals and non-metals) by utilizing the interaction characteristic of a laser beam and a substance. As an advanced manufacturing technology, laser processing has been widely applied to national economic important departments such as automobiles, electronics, electrical appliances, aviation, metallurgy, mechanical manufacturing and the like, and plays an increasingly important role in improving product quality, labor productivity, automation, no pollution, reducing material consumption and the like.
With the development of laser processing technology, laser welding technology increasingly shows its excellent application prospect, and has played a great role in the fields of ship and automobile industry, aerospace manufacturing, medical health and the like. Laser welding can be divided into heat conduction welding and deep fusion welding according to the forming characteristics of a laser welding seam. With the ever increasing laser power density, the welding has evolved from heat transfer welding to deep penetration welding. When the laser power density used for welding is low, the welding form is heat conduction welding, the time required for forming a molten pool is long, and the fusion depth is shallow; when the laser power density used during welding is high, when the laser starts to radiate to the surface of a workpiece, because the laser energy density is high and the melt generated by the workpiece is little, the melt is discharged out of a molten pool under the action of the recoil force of metal vapor to form melt splashing, a small molten pool starts to generate and continuously increases in size along with the increase of the irradiation time, the metal is melted and simultaneously accompanied with strong gasification, the welding form at the moment is deep fusion welding, the fusion depth of the molten pool is large, the depth-to-width ratio of the obtained welding line is large, and the ideal welding effect is easily obtained.
The laser cladding technology is one of laser processing technologies which are actively developed, and the principle of the laser cladding technology is that metal powder is preset on the surface of a base material by a powder spreading or powder feeding method, a high-energy laser beam is focused on the surface of the base material, the focused laser beam irradiates the metal powder on the surface of the base material, the metal powder at the focal position and a thin layer on the surface of the base material are melted to form a molten pool with a certain shape and size, and meanwhile, the molten pool is splashed due to rapid expansion of the powder to be clad when being heated; when the focus of the laser beam moves at a certain speed according to a preset track, the molten pool after the laser beam is removed is rapidly solidified, so that a metal coating with special physical, chemical or mechanical properties is coated on the area swept by the laser beam on the surface of the substrate.
In the technical process of laser welding, cladding, surface treatment and the like of metal materials, certain spatter generated by a high-temperature molten pool is inevitable, in the engineering application process of the existing laser processing technology, a craftsman generally considers harmful to the spatter of the molten pool, the most probable harm is the damage to a laser processing head, for example, an optical lens at the bottom of the laser processing head, which is closest to a workpiece, can be ablated due to the spatter or even cracked due to the absorption of the spatter to laser, and elements (such as an optical fiber, a water pipe, a gas pipe and the like) at the side of the laser processing head can be ablated and damaged due to the adhesion of the spatter or heated and deformed due to the heat radiation of the high-temperature molten pool. Therefore, the treatment is generally to reduce the spatter and prevent the spatter from damaging the laser head, for example by applying a transverse protective air curtain under the optical lens or by applying a protective iron ring directly above the laser head nozzle to block the spatter from affecting the elements on the sides of the laser head.
The existing laser processing quality control is generally open-loop, namely detection and evaluation are carried out by methods such as gold phase analysis, mechanical property test and the like after processing is finished. The online detection method for closed-loop laser processing quality generally comprises plasma spectrum diagnosis, molten pool temperature field monitoring and the like. Plasma spectrum diagnosis is a simple and common method for obtaining the temperature and density of plasma electrons, and is applied to the field of laser welding plasma research by scholars at home and abroad. The measurement is difficult due to the gradient change of electron temperature and electron density of laser plasma in space and instability in time. Most of the current laser welding plasma spectrum diagnosis work only obtains the average temperature and the density of electrons, namely, only single-point measurement is carried out on the plasma, and the change of the electron temperature and the electron density along with time and space is not considered, so that certain difference exists in the measurement result. The monitoring of the temperature field of the molten pool has important significance for controlling the appearance of the laser molten pool, improving the process design and improving the laser processing precision and quality. Due to high laser energy density, small size of a molten pool and complex thermal process, great difficulty is brought to the detection of the temperature field of the molten pool, most researches can only give the temperature of the laser molten pool or a point near the laser molten pool, and then the temperature field distribution is deduced by adopting a mathematical analysis method. With the development of high-temperature detection technology and Charge Coupled Device (CCD) technology, the adoption of CCD for temperature field and dynamic process detection has been rapidly developed, the CCD needs to be combined with image processing technology, the image processing technology processing such as smoothing processing, threshold segmentation, false color and the like is adopted, according to the acquired molten pool image characteristics, the fact that the distribution condition of the laser molten pool temperature field obtained through image processing is possible in principle is achieved, but at present, a closed-loop laser processing quality control device and method based on molten pool splash detection are not available.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a closed-loop laser processing quality control method based on molten pool splashing detection.
The invention is realized by the following technical scheme:
a closed-loop laser processing quality control method based on molten pool splash detection comprises the following steps:
(1) clamping a metal workpiece to be processed, and setting a preprogrammed laser processing path and initial process parameters of laser processing, wherein the initial process parameters comprise laser power, beam advancing speed, defocusing amount, powder/wire feeding rate and protective gas flow;
(2) starting an internal water cooling system of a splash baffle arranged on the laser processing head in a surrounding manner and a circulating water cooling system of the laser processing head; starting N thermal imagers which are uniformly arranged in the circumferential direction of the laser processing head, wherein the N thermal imagers are used for realizing 360-degree detection of the splash baffles; the N thermal imagers circularly acquire infrared temperature field images of the surface of the splash baffle and the space near the surface of the splash baffle by taking Ts as a sampling period, N infrared temperature field images are acquired in each cycle, the N infrared temperature field images acquired in each cycle are spliced and filtered to obtain a panoramic infrared temperature field image, and the cycle is stopped after the panoramic infrared temperature field image is stable; taking the panoramic infrared temperature field image as an initial infrared temperature field panoramic image; wherein N is a positive integer greater than or equal to 1;
(3) outputting a laser beam, outputting synchronous powder/wire feeding and air feeding, starting the pre-programmed relative motion of the laser processing head and the workpiece, and starting laser processing according to the initial process parameters and the pre-programmed laser processing path in the step (1); taking any K positions on a pre-programmed laser processing path as monitoring points, wherein K is a positive integer greater than or equal to 1;
(4) in the laser processing process, the N thermal imagers circularly acquire infrared temperature field images of the surface of the splash baffle and the space near the surface of the splash baffle by taking Ts as a sampling period, and the images are spliced and filtered to obtain a current panoramic infrared temperature field image of the splash baffle, namely current characteristic data of the splash is obtained;
(5) obtaining characteristic data of the current splashed objects at each monitoring point through the current panoramic infrared temperature field image;
if the historical database does not have reference characteristic data, adding the characteristic data of the current splash obtained for the first time into the historical database, and taking the characteristic data as the reference characteristic data;
if the historical database has reference characteristic data, comparing the characteristic data of the current splash with the reference characteristic data; if not, entering the step (6); if the change rate is larger than x%, recording the monitoring point K corresponding to the characteristic data of the current splashiAdding the characteristic data of the current splash into a historical database; simultaneously adjusting one or more process parameters of the laser machining on-line, the adjustment target being such that the adjusted acquisition is obtainedComparing the characteristic data of the current splash with the reference characteristic data, wherein the difference tends to be reduced until the change rate is less than x%; the subsequent laser processing adopts the adjusted process parameters;
(6) repeatedly executing the step (5) until the current processing task is completed, namely all the pre-programmed laser processing paths are processed;
(7) after the processing is finished, the processing quality of all positions recorded in the historical database is analyzed through a metallographic analysis method and a mechanical property analysis method, the characteristic data corresponding to the position where the optimal processing quality is obtained is set as reference characteristic data, the corresponding laser processing technological parameter is set as the initial technological parameter of the same type or the same type of processing task in the future, and the rest data are deleted.
The invention has the following beneficial effects:
1. in the technical processes of laser welding, cladding, surface treatment and the like of metal materials, certain splashing generated by a high-temperature molten pool is inevitable, and the high-temperature molten pool is generally simply treated by the prior art to prevent damage to a laser processing head. However, since the spatter comes from the bath, it carries with it status information of the bath, such as bath temperature, bath movement status, metallurgical status, etc. From the point of view of metal metallurgy, the essence of the quality control of the laser processing technology is that the temperature of a molten pool irradiated by laser is reasonable, the metallurgy is sufficient, and the solidification structure is excellent through the adjustment of technological parameters such as laser power, beam advancing speed, defocusing amount, powder/wire feeding speed, protective gas flow and the like. The invention effectively collects the information of the molten pool splash on line through a unique structural design, enables the real-time analysis of the laser processing process quality to be feasible in the laser processing process, and realizes the complete closed-loop control of the laser processing process quality by combining the online real-time adjustment of the laser processing process parameters.
2. The prior art often adopts an element which is arranged above a nozzle of a laser processing head and used for preventing splashes from influencing the side edge of the laser processing head, but the protective iron ring can be deformed due to heating after the working time is long. The closed-loop laser processing quality control device based on molten pool splash detection not only has the closed-loop control function of the laser processing process quality described in the above beneficial effect 1, but also has a more excellent protection effect than the prior art. Particularly, a circulating water cooling structure is designed in the umbrella-shaped splash baffle, so that the umbrella-shaped splash baffle can work for a long time without deformation, and elements (such as optical fibers, water pipes, air pipes and the like) on the side edge of the laser processing head can be effectively protected from being ablated and damaged due to splash adhesion or heating deformation due to heat radiation of a high-temperature molten pool; and the transverse protective air curtain structure is designed compatibly, so that the optical lens of the laser processing head can be effectively protected from being damaged by splashes.
3. The specially designed umbrella-shaped splash baffle can collect splashes to support a thermal imager to collect splash information, and can generate a gathering effect on molten pool protective gas applied from a nozzle of a processing head in a laser processing process so that the protective gas is not easy to escape, more protective gas is gathered above the molten pool, and a better protection effect is provided.
4. The internal circulating water cooling of the umbrella-shaped splash baffle enables the temperature of the baffle to be low and to be kept in a basically balanced stable state, so that bonded splashes can be continuously and rapidly cooled, the bonded splashes accumulated on the baffle are also in a cooling state, the baffle is not prone to thermal deformation, the temperature field effect of accumulated temperature rise is avoided for the bonded and accumulated splashes, a stable background temperature field is provided for a thermal imager, and the thermal imager can accurately measure the temperature and the form distribution of the current splashes.
5. The N thermal imagers can synthesize the real-time temperature field images of the splashes of the full-circumference baffle, and the rich information (temperature, flight speed, overall dimension and the like) of the splashes can be detected according to the plurality of real-time temperature field images of the splashes collected within a period of time.
6. The N thermal imagers are not directly opposite to the molten pool in the installation mode, so that the thermal imagers can be protected from being polluted by splashes, the shielding influence of most plasma arc light above the laser processing molten pool can be eliminated, and clear splash information can be obtained.
7. The closed-loop laser processing quality control device and method based on molten pool splash detection have two convergence iterative process optimization effects, firstly, the laser processing process parameters can be subjected to real-time closed-loop control and dynamic fine adjustment in the laser processing process to keep the process quality stable (close to preset reference characteristic data), and secondly, for the same kind (or similar kinds) and multi-batch processing conditions, the optimal processing process parameters and the optimal processing parameter adjustment rule can be obtained through closed-loop iteration through the process information recording and quality detection of each batch (the manual feedback of the processing quality of metallographic analysis and mechanical property analysis is regarded as one loop of the closed-loop control).
8. The method is suitable for the thickness of the processed workpiece, is suitable for different processing technologies (welding, cladding, surface treatment and the like), and has the advantages of wide adaptability, simple and convenient detection, rapid feedback and high automation degree.
Drawings
FIG. 1 is a schematic structural diagram of a closed-loop laser processing quality control device based on molten pool splash detection according to the invention;
the meaning of each number in the figure is:
1-laser processing head; 2-splash baffles; 3-a workpiece; 4-a thermal imager; 5-a nozzle holding part; 6-a cavity; 7-a molten pool; 8-spatter; 9-protective lens; 10-protective gas curtain; 11-circulating water cooling channel; 12-machining a laser beam; 13-a focusing mirror; 14-a focusing lens holder; 15-a conical processing nozzle; 16-a ring-like projection structure; 17-nozzle orifice; 19-protective lens adjusting frame; 20-a detachable structure; 21-a water inlet; 22-water outlet.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.
The invention provides a closed-loop laser processing quality control device based on molten pool splashing detection, which comprises a laser processing head 1, a splash baffle 2 and a plurality of thermal imagers 4, as shown in figure 1.
The laser processing head 1 is cylindrical, a conical processing nozzle 15 is arranged at the tail end of the bottom of the laser processing head, a focusing lens 13 and a protective lens 9 are arranged in the cavity 6 inside the laser processing head, and a protective air curtain 10 is arranged on the outer side wall of the cavity.
The conical processing nozzle 15 is installed at the bottom of the laser processing head 1 through the nozzle holding part 5, and a circulating water cooling mechanism is arranged in the side wall of the conical processing nozzle 15.
The focusing lens 13 is clamped on the inner wall of the laser processing head 1 through a focusing lens holding frame 14 and an annular protruding structure 16, the protective lens 9 is arranged below the focusing lens 13 through a protective lens adjusting frame 19 and is coaxially arranged with the focusing lens 13, and the protective lens 9 can prevent splashes 8, smoke dust and the like from polluting the focusing lens 13.
The protective air curtain 10 is arranged on the outer side wall of the laser processing head 1 and is positioned below the protective lens 9 and above the conical processing nozzle 15; the gas flow direction of the protective gas curtain 10 is parallel to the lens of the focusing lens 13, and splashes, smoke and the like can be blown away from the protective lens 9.
The machining laser beam 12 is incident from the top or side hole of the laser machining head 1, focused by the focusing mirror 13, and then output to the surface of the workpiece 3 through the tapered machining nozzle 15.
The splash baffle 2 surrounds the periphery of the laser processing head 1, is umbrella-shaped and made of metal, has a certain thickness, is internally provided with a circulating water cooling channel 11, the lower surface of the splash baffle 2 faces the workpiece, and the upper surface of the splash baffle 2 is provided with a water inlet 21 and a water outlet 22; the splash guard 2 is connected with the laser processing head 1 through a detachable structure 20, so that the splash guard is convenient to replace and can be detached to be used again after being used by a grinding device to remove splashes adhered after multiple processing.
The splash baffle 2 can collect the splashes 8 on one hand and provide support for the thermal imager 4 to collect the information of the splashes 8, and on the other hand can prevent the protective gas from escaping, so that more protective gas is gathered above the molten pool 7, and a better protection effect is provided.
Circulating water cooling in the circulating water cooling channel 11 makes the splash baffle 2 self keep the cooling state to can cool off the splash that bonds fast, make the bonding splash that accumulates on the splash baffle 2 also be the cooling state, this one side makes baffle self be difficult for taking place thermal deformation, on the other hand makes the temperature field effect that the splash that bonds the accumulation can not produce the accumulative heating, provides a stable background temperature field for thermal imager 4, makes thermal imager 4 can be accurate the temperature and the form distribution of present splash of survey.
The thermal imagers 4 are uniformly arranged on the outer wall of the laser processing head and are located below the spatter shield 2. The multiple thermal imagers 4 can detect the splash baffles 2 in 360 degrees, for example, 6 thermal imagers 4 are provided, the monitoring area of the baffle corresponding to each thermal imager 4 is a sector area of 60 degrees or more, and 6 infrared temperature field images obtained by the 6 thermal imagers are subjected to image processing such as splicing and filtering to obtain a panoramic infrared temperature field image.
The thermal imagers 4 can synthesize real-time temperature field images of the splashes of the full-circumference baffle, and rich information (temperature, flight speed, overall dimensions and the like) of the splashes can be detected according to the real-time temperature field images of the splashes collected within a period of time. The thermal imagers 4 are not directly opposite to the molten pool 7, so that the thermal imagers can be protected from being polluted by splashes, the shielding influence of most plasma arc light above the laser processing molten pool can be eliminated, and clear splash information can be obtained.
The invention also provides a closed-loop laser processing quality control method based on molten pool splash detection, which comprises the following steps:
(1) and clamping a metal workpiece to be processed, and setting a preprogrammed laser processing path and initial process parameters of laser processing (laser welding, laser cladding or surface treatment), wherein the initial process parameters comprise laser power, beam advancing speed, defocusing amount, powder/wire feeding rate, protective gas flow and the like.
(2) Starting an internal water cooling system of a splash baffle arranged on the laser processing head in a surrounding manner and a circulating water cooling system of the laser processing head; starting N thermal imagers which are uniformly arranged in the circumferential direction of the laser processing head, wherein the N thermal imagers are used for realizing 360-degree detection of the splash baffles; the N thermal imagers circularly acquire infrared temperature field images of the surface of the splash baffle and the space near the surface of the splash baffle by taking Ts as a sampling period, N infrared temperature field images are acquired in each cycle, the N infrared temperature field images acquired in each cycle are subjected to image processing such as splicing and filtering to obtain a panoramic infrared temperature field image, and the cycle is stopped after the panoramic infrared temperature field image is stabilized; taking the panoramic infrared temperature field image as an initial infrared temperature field panoramic image; wherein N is a positive integer greater than or equal to 1; the stability means that the difference between the next panoramic image and the previous panoramic image is less than a%, the value of a can be different according to different processing applications, and the value of a is only between 1 and 20.
(3) Outputting a laser beam, outputting synchronous powder/wire feeding and air feeding, starting the pre-programmed relative motion of the laser processing head and the workpiece, and starting laser processing according to the initial process parameters and the pre-programmed laser processing path in the step (1); taking any K positions on a pre-programmed laser processing path as monitoring points, wherein K is a positive integer greater than or equal to 1; the position of the monitoring point can calculate the displacement between the position and the starting point and the determined moment when the laser beam passes the position (the accumulated travelling time of the laser beam from the starting point to the position) according to a pre-programmed laser processing path and the travelling speed of the laser beam.
(4) In the laser processing process, the N thermal imagers circularly acquire infrared temperature field images of the surface of the splash baffle and the space near the surface of the splash baffle by taking Ts as a sampling period, and perform image processing such as splicing, filtering and the like to obtain a current panoramic infrared temperature field image of the splash baffle, namely to obtain the characteristic data of the current splash;
in the technical processes of laser welding, cladding, surface treatment and the like of metal materials, certain splashes are inevitably generated by a high-temperature molten pool, so that in the current panoramic infrared temperature field image of the splash baffle, the shape profiles, the relative size comparison (the absolute size of the splashes can be calculated through the field calibration of a thermal imager), the temperature distribution of the splashes and the spatial position distribution density of the splashes are recorded, and the information is called as characteristic data of the splashes;
(5) obtaining characteristic data of the current splashed objects at each monitoring point through the current panoramic infrared temperature field image;
if the historical database does not have reference characteristic data, adding the characteristic data of the current splash obtained for the first time into the historical database, and taking the characteristic data as the reference characteristic data;
if the historical database has reference characteristic data, comparing the characteristic data of the current splash with the reference characteristic data; if not, entering the step (6); if the change rate is significantly changed, namely the change rate is greater than x% (x is determined by processing experience, and the value of x is between 1 and 20, for example, the change rate is greater than 10%), recording the monitoring point K corresponding to the characteristic data of the current splashiAdding the characteristic data of the current splash into a historical database; simultaneously, one or more process parameters of laser processing (welding or cladding) are adjusted on line, the adjustable process parameters comprise laser power, beam advancing speed, defocusing amount, powder/wire feeding speed, protective gas flow and the like, the adjustment rule is adjusted according to the empirical rule of the laser processing process (for example, when a thermal imager detects that the number of splashes is increased and the temperature is increased, the situation that the powder feeding speed is too high or the laser power is too high at the moment is indicated, so that the powder feeding speed or the laser power is fed back to a laser processing system, and the powder feeding speed or the laser power is adjusted in time), and the aim is to enable the characteristic data of the current splashes obtained after adjustment to be compared with the reference characteristic data, and the difference tends to be reduced until; the subsequent laser processing adopts the adjusted process parameters;
(6) repeatedly executing the step (5) until the current processing task is completed, namely all the pre-programmed laser processing paths are processed;
(7) after the processing is finished, analyzing the processing quality of all positions recorded in the historical database by methods of metallographic analysis, mechanical property analysis and the like, setting the characteristic data corresponding to the position with the optimal processing quality as reference characteristic data, setting the corresponding laser processing technological parameters as initial technological parameters of the same type or the same type of processing tasks in the future, and deleting the rest data.
For the same (or similar variety) and multi-batch processing conditions, the optimal processing technological parameters and the optimal processing parameter adjustment rules can be obtained iteratively through the process information recording and quality detection of each batch and through the multiple processing tasks from (1) to (7).
It will be obvious to those skilled in the art that the present invention may be varied in many ways, and that such variations are not to be regarded as a departure from the scope of the invention. All such modifications as would be obvious to one skilled in the art are intended to be included within the scope of this claim.
Claims (1)
1. A closed-loop laser processing quality control method based on molten pool splash detection is characterized by comprising the following steps:
(1) clamping a metal workpiece to be processed, and setting a preprogrammed laser processing path and initial process parameters of laser processing, wherein the initial process parameters comprise laser power, beam advancing speed, defocusing amount, powder/wire feeding rate and protective gas flow;
(2) starting an internal water cooling system of a splash baffle arranged on the laser processing head in a surrounding manner and a circulating water cooling system of the laser processing head; starting N thermal imagers which are uniformly arranged in the circumferential direction of the laser processing head, wherein the N thermal imagers are used for realizing 360-degree detection of the splash baffles; the N thermal imagers circularly acquire infrared temperature field images of the surface of the splash baffle and the space near the surface of the splash baffle by taking Ts as a sampling period, N infrared temperature field images are acquired in each cycle, the N infrared temperature field images acquired in each cycle are spliced and filtered to obtain a panoramic infrared temperature field image, and the cycle is stopped after the panoramic infrared temperature field image is stable; taking the panoramic infrared temperature field image as an initial infrared temperature field panoramic image; wherein N is a positive integer greater than or equal to 1;
(3) outputting a laser beam, outputting synchronous powder/wire feeding and air feeding, starting the pre-programmed relative motion of the laser processing head and the workpiece, and starting laser processing according to the initial process parameters and the pre-programmed laser processing path in the step (1); taking any K positions on a pre-programmed laser processing path as monitoring points, wherein K is a positive integer greater than or equal to 1;
(4) in the laser processing process, the N thermal imagers circularly acquire infrared temperature field images of the surface of the splash baffle and the space near the surface of the splash baffle by taking Ts as a sampling period, and the images are spliced and filtered to obtain a current panoramic infrared temperature field image of the splash baffle, namely current characteristic data of the splash is obtained;
(5) obtaining characteristic data of the current splashed objects at each monitoring point through the current panoramic infrared temperature field image;
if the historical database does not have reference characteristic data, adding the characteristic data of the current splash obtained for the first time into the historical database, and taking the characteristic data as the reference characteristic data;
if the historical database has reference characteristic data, comparing the characteristic data of the current splash with the reference characteristic data; if not, entering the step (6); if the change rate is larger than x%, recording the monitoring point K corresponding to the characteristic data of the current splashiAdding the characteristic data of the current splash into a historical database; simultaneously, one or more process parameters of laser processing are adjusted on line, the adjustment target is to enable the feature data of the current splash obtained after adjustment to be compared with the reference feature data, and the difference tends to be reduced until the change rate is less than x%; the subsequent laser processing adopts the adjusted process parameters; the value of x is between 1 and 20;
(6) repeatedly executing the step (5) until the current processing task is completed, namely all the pre-programmed laser processing paths are processed;
(7) after the processing is finished, the processing quality of all positions recorded in the historical database is analyzed through a metallographic analysis method and a mechanical property analysis method, the characteristic data corresponding to the position where the optimal processing quality is obtained is set as reference characteristic data, the corresponding laser processing technological parameter is set as the initial technological parameter of the same type or the same type of processing task in the future, and the rest data are deleted.
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| CN201810763091.2A CN108941939B (en) | 2017-07-12 | 2017-07-12 | Closed-loop laser processing quality control method based on molten pool splash detection |
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| CN201810763091.2A CN108941939B (en) | 2017-07-12 | 2017-07-12 | Closed-loop laser processing quality control method based on molten pool splash detection |
| CN201710565596.3A CN107234351B (en) | 2017-07-12 | 2017-07-12 | Closed loop laser processing quality control device and method based on molten bath splashing detection |
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| CN109365813A (en) * | 2018-12-18 | 2019-02-22 | 苏州大学 | A kind of three-dimensional space any direction laser cladding apparatus |
| CN109351973A (en) * | 2018-12-18 | 2019-02-19 | 苏州大学 | A kind of three-dimensional space any direction cladding forming method |
| DE102019209100A1 (en) * | 2019-06-24 | 2020-12-24 | Robert Bosch Gmbh | Quality monitoring for a laser beam welding process |
| KR102383193B1 (en) * | 2019-10-21 | 2022-04-06 | 삼성에스디아이 주식회사 | Protecting module for laser welding device |
| CN111299850B (en) * | 2019-10-31 | 2021-06-15 | 广东宏石激光技术股份有限公司 | Laser processing method |
| CN113732502B (en) * | 2020-05-29 | 2023-04-28 | 大族激光科技产业集团股份有限公司 | Laser welding protection device, laser welding device and laser welding method |
| CN112935546B (en) * | 2021-03-17 | 2022-09-16 | 中国科学院宁波材料技术与工程研究所 | Laser shock welding device based on direct impact type constraint layer |
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