RU2258589C1 - Method and device for diagnostics and quality control of laser welding - Google Patents

Abstract

FIELD: laser welding equipment.

SUBSTANCE: as welding tool laser beam is used. Number of welding point, current position, seam length or melting space are identified by counting signals of welding process presence and comparing these to supporting time counts. Number of welded seam is identified on basis of welding stop signal or open seam edge signal or closed seam edge signal appropriately for welding technology. Number of welded product is identified on basis of number of welded seams and/or lengths thereof. Probability of occurrence of non-solidity defects or reasons of decrease of laser equipment nodes resource are determined for current welding technology on basis of equality or exceeding of sixth threshold value by total signal I_t. exceeding of edges of welded parts is determined by threshold amplitude selection of signals I_i of welded parts, tracked appropriately for current welding technology from front and sides of joint trajectory. Actual or possible from pre-threshold comparison reasons of defect are identified on basis of appearance of signals of threshold or pre-threshold unacceptable excesses of edges, deviations from joint, space width, decreases of laser emission intensiveness levels, amplitude, length, frequency of intensiveness signals of laser charge, increase of welding speed or unacceptable changes of laser spot diameter. Actual or pre-threshold based possible reasons of overheating and exhausts are identified on basis of appearance of signals of threshold or pre-threshold levels of unacceptable excesses of intensiveness of laser emission, amplitude, length, frequency of signals of laser charge, decrease of welding speed and unacceptable changes of laser spot diameter. Appropriately for current welding technology signals of unacceptable signal states and their actual or possible reasons are recorded for corrections of welding process in real time scale or re-welding of defect portion or stopping process in case of long disruption of optimal welding process and signals for automatic control of laser welding process are formed by adaptive amplitude change, laser charge length, welding speed, pulses frequency and laser emission focusing. Device is provided with laser block with laser beam intensiveness indicator, laser charge current indicator, positioned in power source block, and electronic synchronization block. Operation block is electrically connected by input and output to infrared converter through electronic

synchronization block, which is connected to input and output of control block, laser charge current indicator and laser beam intensiveness indicator. Infrared converter is made with possible orientation by areas of surfaces adjacent areas tracking areas, positioned along drive of relative movement of laser beam along joint, in front and on the sides of joint trajectory or relatively to beam axis for controlling approaches to seam edge, to ending of seam of solid metal of closed edge and to ending of seam of edge of closed edge, vicinity of surface of heat track of formed welding tub, vicinity of surface of laser spot focusing, vicinity of heat tracks of controlled laser block surfaces for diagnosing their abnormal modes of operation and deviations.

EFFECT: higher quality, lower costs, higher speed of operation, higher personnel safety, higher efficiency.

2 cl, 1 dwg

Description

The invention relates to the field of welding equipment and can be used in solving problems of diagnostics, multi-parameter control in all processes of high-quality, high-performance laser welding. There are no restrictions on the types of technologies, materials and equipment.

Known methods for diagnosing and controlling the quality of laser welding, based on the determination of the individual characteristics of the laser technological installation. So, for example, in US patent No. 6355905, 7 V 23 K 26/00, 2002, in the control mode with feedback on the display, the average laser pulse energy and the average laser output power are calculated from the measured laser output power, voltage and current of the pump lamp . In US patent No. 6392192, 7 23 K 26/02, 2002 in the control mode of the laser focus is determined by the thermal load on the optical connector and the focusing system.

In these examples of diagnosing the states of individual components of the laser beam formation process, the position of the parts to be welded, which determines the quality of welding, is not controlled.

Among the known methods for diagnosing and controlling the quality of laser welding, the most effective in terms of the number of diagnosed functions is the use of optoelectronic monitoring of infrared radiation (IKI) of the laser beam and its effect on the materials being welded. In US patent No. 6555780, 7 In 23 K 26/20, 2003, when controlling the power and focusing of the laser by experimental measurements of the chromatic aberration of the lenses, the dimensions of the weld pool and the focal spot of the laser beam are determined. An example is also US patent 6596961, 7 V 23 K 26/20, 2003, in which the laser welding process is optically controlled based on the diagnosis of penetration conditions based on the measurement of position sensor signals (CCD camera with an auxiliary laser or spring-loaded mechanical sensor) and a process sensor (plasma detector or visual two-dimensional system).

In these examples, the diagnostics of the states of the components of laser penetration is shown. However, in the indicated analogues, the full range of diagnosed conditions and causes of non-standard deviations characterizing the quality of welding is not determined.

With varying complexity of hardware and software implementation, the limitations in the application of many of the known methods for laser welding diagnostics are as follows:

- in their specialization in certain types of welding;

- the lack of consistency and complexity of control of the geometry of the welded parts, movement, metallurgical defects of discontinuity and the gas protection process.

A common drawback of the known methods is the solution of particular problems with complexity corresponding to the number of controlled functions, without the use of effective information compression.

The closest analogue to the invention is the method and the device described therein according to the patent of the Russian Federation 2127177, 7 V 23 K 9/10.

A known method for diagnosing and controlling the quality of laser welding includes measuring the spatio-temporal signals of infrared radiation from heat waves of penetration of traces of the effects of the welding tool in the visible areas on the surface of the parts being welded, converting temporal, spatial changes in signal amplitudes into gradient-extreme signals by means of the accumulation modeled by the differential heat equation and blur, the conversion of infrared radiation into an informative electron natural signals by a transducer with point surface thermosensitive elements, with receiving from each of them an electric signal Andi, where i is the element number, determining the relative deviations of the welding tool from the joint between the parts to be welded and / or from the angle between the parts and the axis of the welding tool by amplitude selection of signals And i of the welded parts, endorsed according to the specified welding technology in front, on the sides of the joint path or relative to the axis of the welding tool, and along the region to be visualized, including the surface region of the heat penetration wave, the determination of the presence of the welding process when the first threshold value is equal or exceeded, the lack of penetration when the equation is equal or reduced relative to the second threshold value, the determination of overheating when the third threshold value is equal or exceeded for the total signals And _Σ from all heat-sensitive temperature sensor elements, determination of the emission of molten material when the emission thresholds are equal or exceed time derivative of the total signal ∂I _Σ / ∂t, determination of the navigation characteristics of motion control by comparing And _{Σ of the} corresponding areas of the joint for tacking with the fourth, for the closed edge of the seam, with the fifth, for the open edge, with zero threshold values, respectively, of the specified welding technology.

This solution provides a comprehensive diagnosis of laser welding conditions by systematically monitoring the IR of thermal penetration waves, the geometry and relative motion of the parts being welded, and metallurgical discontinuities. Effective information compression is used based on modeling the differential heat equation.

The limitations of this method are associated with the absence of a full range of diagnosed conditions of welding quality, taking into account violations of the gas protection of the welding zone, as well as the reasons for non-standard deviations of these conditions.

Accordingly, the known device for diagnosing and controlling the quality of laser welding contains an infrared converter, which visually visually inspects the thermal trace of the laser effect on the materials being welded, and an operation unit connected to the recorder by the output.

This device provides the use of effective information compression and systematic monitoring of the conditions and quality characteristics of laser welding with partial automation of control by IRI penetration and geometry of the welded parts.

The limitations of this device are associated with the lack of a comprehensive diagnosis of the conditions of welding quality, taking into account violations of the gas protection of the welding zone, as well as the causes of non-standard deviations of these conditions to ensure that control that eliminates the non-standard, including adaptive.

The basis of the invention is the task of improving the method of diagnostics of laser welding, in which due to a change in the methods, operations, conditions for monitoring and analyzing the characteristics of IRI of thermal traces of laser penetration, shaping of the welded joint and discontinuities, as well as signals from auxiliary sensors, the following technical result is obtained.

For various application conditions with the possibility of ensuring high technological reliability, a more complete set of functions for monitoring and diagnosing the laser welding process is realized. Including, respectively, a given welding technology, the number of the welding point, the current position, the length of the seam or the passage of penetration, the number of the seam being welded, the number of the product being welded are identified; determine the possibility of the occurrence of discontinuity defects, reasons for reducing the resource of laser equipment nodes in case of gas protection violations; determine the excess edges of the welded parts; identify the actual or pre-threshold comparisons of the possible causes of lack of penetration, overheating, emissions; register signals of unacceptable penetration conditions, their actual or possible reasons for real-time adjustments of the welding process or correction by remelting of a defective section or process shutdown during prolonged violation of the optimal welding process; generate signals for automatic control of the laser welding process. In addition, in various ways determine the change in the level of laser energy, power; unacceptable joint gap of the welded parts; unacceptable changes in the magnitude of the laser spot.

The basis of the invention is also the task of improving the device for implementing the diagnostic method of laser welding by introducing new elements and their relationships, which provides the following technical result.

The reliability of detection and forecasting of unacceptable deviations in the laser welding process is significantly increased, many of the causes of defects are eliminated due to more effective systemic organization in real time of spatio-temporal modeling, signal transformations, as well as amplitude tracking, monitoring and diagnostic transformations during setup and in real laser welding time.

The problem is solved in that in a method for diagnosing and controlling the quality of laser welding, which consists in measuring the spatio-temporal signals of infrared radiation of heat waves of penetration of traces of the effects of the welding tool in the visible areas on the surface of the parts being welded, converting temporal, spatial changes in signal amplitudes into gradient-extreme signals by means of the accumulation and smearing modeled by the differential heat equation, generation of infrared radiation into informative electrical signals by a transducer with point surface thermally sensitive elements, with receiving from each of them an electric signal Ii, where i is the element number, determining the relative deviations of the welding tool from the joint between the parts to be welded and / or from the angle between the parts and the axis of the welding tool by amplitude selection of signals And i of the parts to be welded, sighted according to a given welding technology in front, on the sides of the path and the joint or relative to the axis of the welding tool, and for the sighted area, including the surface region of the heat penetration wave, determining the presence of the welding process when the first threshold value is equal or exceeding, determining the lack of penetration when equal or decreasing relative to the second threshold value, determining the overheating when the third or equal threshold value for the total signals And _Σ from all thermosensitive elements of the temperature sensor, determining the emission of molten material at p or exceeding the threshold emission values for the time derivative of the total signal ∂I _Σ / ∂t, determining the navigation characteristics of the motion control by comparing the And _{Σ of the} corresponding areas of sight of the joint for the tack with the fourth, for the closed edge of the seam, with the fifth, for the open edge, with zero threshold values according to a given welding technology, according to the invention, a laser beam is used as a welding tool, the number of the welding point, the current position, the length of the seam or other starting penetration by counting the signals of the presence of the welding process and comparing them with benchmarks, identify the number of the welded seam by the signal of the end of welding or by the signal of the open edge of the seam or by the signal of the closed edge of the seam, respectively, of the specified welding technology, identify the number of the welded product by the number of welded seams and / or seam lengths, determine the possibility of discontinuity defects, reasons for reducing the resource of laser equipment nodes for a given welding technology, equal to TSS or exceed the sixth threshold value sum signal and _Σ, determine the excess edges of the parts being welded by the threshold amplitude selection signals ANDi welded parts viziruemyh respectively predetermined welding technology front, at the sides of the trajectory of the joint, identifying actual or subthreshold comparisons possible causes of lack of fusion from the appearance of signals threshold or pre-threshold levels of unacceptable excesses of the edges, deviations from the joint, the size of the gap, the decrease in levels of intensity These laser radiation, the amplitude, duration, frequency of the signals of the laser pump intensity, the increase in welding speed, unacceptable changes in the laser spot value, identify the actual or pre-threshold comparisons of possible causes of overheating, emissions due to the appearance of signals of threshold or pre-threshold levels of unacceptable excesses of the laser radiation intensity, amplitude, duration, frequency of laser pump intensity signals, reduction of welding speed, unacceptable changes in the value of the laser spot a, they register, according to the specified welding technology, signals of unacceptable penetration states, their actual or possible reasons for real-time adjustments of the welding process or correction of a defective area by re-melting or stopping a process with a long violation of the optimal welding process, generate signals for automatic control of the laser welding process by adaptively changing the amplitude , laser pump duration, welding speed, pulse frequency, focusing of laser radiation.

In addition, in a method for diagnosing and controlling the quality of laser welding, according to the invention:

- determine the change in the level of laser power by monitoring the intensity of the laser beam with an infrared sensor at a wavelength of laser exposure to the material;

- determine the change in the level of laser power and / or its cause by monitoring the pump current of the laser beam;

- determine the presence and cause of changes in the level of laser radiation intensity, the presence of changes in the duration and frequency of the laser pulses due to the control of the pump current of the laser beam;

- identify the unacceptable joint gap of the welded parts in the presence of lack of penetration, concomitant discontinuity defects due to the absence of other causes of lack of penetration;

- identify the unacceptable size of the joint gap of the welded parts by threshold control of the reduction of the amplitudes of signals And thermal traces of penetration, while the heat-sensitive element is sighted at the joint of the welded parts;

- identify the actual or possible causes of the occurrence of discontinuity defects, the reasons for the decrease in the resource of laser equipment nodes for a given welding technology by deviations from the threshold levels of the electrical signals of the blowing and / or exhaust protective gas mixture sensors in the welding zone;

- identify unacceptable changes in the magnitude of the laser spot for the diagnosed states of lack of penetration, overheating, emission in the absence of other causes of these diagnosed conditions;

- identify unacceptable changes in the magnitude of the laser spot, by threshold control, respectively, decrease or increase signals And _Σ thermal traces at the wavelength of laser exposure to the material.

The problem is also solved by the fact that in the device for diagnostics and quality control of laser welding, containing an infrared converter for visualizing the thermal input of the thermal trace of the impact of the welding tool on the materials being welded, the control unit and the operating unit connected to the recorder with an output, it is equipped with an electronic matching unit according to the invention and a laser was used as a welding tool, and the electronic matching unit is connected to the operating unit, infrared transducer and control unit.

In addition, the device for diagnosis and quality control of laser welding, according to the invention is equipped with:

- a pump current sensor located in the power supply unit and connected to the electronic matching unit;

- a temperature sensor for the cooling medium located in the cooling unit and connected to the electronic matching unit;

- a laser beam intensity sensor located in the laser unit and connected to the electronic matching unit;

- blowing and exhaust sensors located in the gas protection unit and connected to the electronic matching unit.

The invention is illustrated in the drawing.

Figure 1 presents a block diagram of a device that implements a method for diagnosing and controlling the quality of laser welding, when diagnosing abnormal technological conditions and detecting their causes in the circuit of various laser welding processes.

In the circuit in figure 1 controlled by the device 17 for diagnosis and quality control of laser welding, the technological process is determined by the laser exposure of the installation 1.

The laser welding system 1, includes blocks 2-12 and a laser beam 13.

The apparatus 1 comprises a power supply unit 2 with a laser pump current sensor 3 located therein, a cooling unit 4 with a coolant temperature sensor located therein, a laser unit 6 with a laser beam intensity sensor 7 located therein, a gas protection unit for the welding zone 8 s located therein sensors blowing 9 and exhaust 10, the actuator 11 move the welded parts 14 relative to the laser beam 13 and the control unit 12.

In Fig.1, the positions of the control object are presented, respectively: 14 - welded parts; 15 - zone of focusing of the laser beam 13 on the surface of the welded parts 14, 16 - zone of sight of the IRI of thermal traces of thermal images of the processes of functioning of the equipment and shaping of laser penetration.

The laser welding diagnostic and quality control device 17 contains an infrared converter 18 of the visible thermal traces of the objects being monitored, as well as an operation unit 20 electrically connected to the converter 18 by an input and output through an electronic matching unit 19 and outputs to the input and output of block 12 and to the input of the recorder 21. In addition to the block 20 through the block 19 can be connected to the outputs of the sensors of the pump current of the laser 3, the temperature of the cooling medium 5, the intensity of the laser beam 7, blowing 9 and hood 10.

The device 17 may be provided for remote transmission of IKI through refractory, reflex elements and optical fibers. And also for reliable protection against sparks, splashes, transmitting IRs can be supplied, for example, mesh screens made of highly heat-conducting metal. But this is not shown in FIG. 1 for simplicity.

The purpose of the individual elements of the device 17 is as follows.

The sensor 3 of the laser pump current in the power supply unit 2 determines the current changes that directly characterize the causes of abnormal diagnosed states of lack of penetration, overheating, emissions and burns.

The temperature sensor 5 of the cooling medium as part of the cooling unit 4 determines the temperature changes characterizing abnormal forced modes and malfunctions in the formation of the required laser exposure.

The sensor 7 of the intensity of the laser beam in the laser unit 6 determines the wavelength of the laser radiation changes in the power of the laser beam, characterizing the causes of abnormal diagnosed conditions.

Sensors blowing 9 and hood 10, as part of the gas protection unit 8, determine abnormal changes in modes, problems in the supply of protective gas and the suction of harmful laser products. These changes characterize the causes of abnormal diagnosable states of the appearance of discontinuity defects, a decrease in the resource of laser equipment units.

An infrared converter 18 is connected to the input and output of the electronic matching unit 19 by an input and an output 19. It is intended mainly for the optical input of a zone 16 of the thermal traces of laser radiation 15 on the materials to be welded 14 and the formation of the initial signals by spatio-temporal conversion of the visual thermal signals into IR signals traces. Depending on the specific tasks of welding and the execution of the optoelectronic channels, the transducer 18 can be performed as follows.

In the form of individual heat receivers, including pyroelectric, conventional or position-sensitive modules, pyroelectric rulers of sensitive elements of IKI.

In the form of thermosensitive multi-element semiconductor structures for detecting and recognizing IKI objects with electronic scanning from block 20 through block 19 by thermal receivers of the indicated areas and zones of sight.

In the form of a combination of position-sensitive detection modules and multi-element structures for monitoring and recognizing IKI objects.

Block 18 is oriented in the following areas of sight.

- Surroundings of surfaces located along the relative motion of the laser beam along the joint, in front, on the sides of the joint path or relative to the axis of the beam. Including, for control of approaches: to a seam tack; to the end of the seam of the solid metal of the closed edge; to the end of the seam of the edge (s) of the open edge.

- Surroundings of the surface of the thermal trace of the formed weld pool.

- Neighborhoods of the focusing surface of the laser spot for thermal receivers of laser exposure to the material.

- Neighborhoods of thermal traces of controlled surfaces of laser equipment in blocks 2, 4, 6, 8, 11, 12 to diagnose their abnormal conditions and deviations. The corresponding connections of the transducer 18 with these blocks are determined by the specified laser welding technology and are not shown in FIG. 1 for simplicity.

The selection of optimal conditions for the sighting of the transducer 18 can be carried out at the stage of tuning, testing of technological samples. Moreover, on the samples in different angles, different zones of sight and thermal receivers of the transducer 18 can be used.

Taking into account the specific technology, driving dynamics, and the temporary welding mode, the area of the region to be seen, the distance to it, and the angle of sight are selected from conditions of sufficient sensitivity and noise immunity. First of all, from overheating, spray of molten metal and other thermochemical influences harmful to optoelectronics.

In the device 17, the electronic matching unit 19, as shown in FIG. 1, electrically connects the infrared converter 18, auxiliary sensors 3, 5, 7, 9, 10 and the control unit 12 to the operation unit 20, performing interface functions. It is designed to optimally interface the electrical signals of these units.

In the device 17, the operation unit 20 is electrically connected by the output to the input of the recorder 21. Unit 20 is a computer or, in a number of specialized applications, a microprocessor implementation. The functions of block 20 are provided by communication with the converter 18 through block 19, with blocks 3, 5, 7, 9, 10, 12, and directly with block 21. They consist of the following transformations: initial settings taking into account sighting and focusing on informative areas and zones as well as input thresholds and technological parameters of laser welding; amplitude threshold tracking and algorithmic signal processing, presentation of diagnostic information and abnormal state signals for adaptive control of the laser welding process.

The registrar 21 is electrically connected to the output of the operation unit 20. It can be autonomous or be a part of the means of computer implementation of the unit 12. The registrar 21 is designed to provide tuning, adjustment, visibility when manually setting up and documenting the results of the functions performed by the device 17.

Further consideration of the essence of the invention on specific, purely illustrative examples of its use for various laser welding processes does not mean that such solutions are the only ones possible and will exhaust the entire scope of the technical solution.

A method for diagnosing and controlling the quality of laser welding during operation of the device 17 according to figure 1 is as follows.

After turning on the device 17 in the block 20 in the setting mode according to the specified welding technology, threshold levels of P are entered.

In particular, for IgES gradient-extreme signals and auxiliary diagnostic signals, these are thresholds: five main diagnosed states (P1-P3, Pv, P6), three navigation characteristics of motion control (P4, P5, P0), three reasons for abnormal penetration conditions mainly from asymmetry geometry of the joint (P7, P8, P9), two reasons for abnormal states from gas protection violations (respectively P10.1, P10.2), two reasons for abnormal penetration states from laser energy parameters (respectively P11.1, P11.2), three P causes of abnormal penetration conditions from temporary penetration parameters (P12.1, P12.2 and P13.1, P13.2 from block 3, respectively; P14.1, P14.2 from transducer 18), a sign of abnormal states of laser energy from overheating of the cooling medium (A15).

These are the thresholds: the smallest first for the presence of the welding process - P1; the second for lack of penetration - P2; the third for overheating - P3; for emissions of molten material - Pv; the fourth for the seam tack - P4; fifth for the closed edge of the seam - P5; zero for the open edge - П0; the sixth one for violations of gas protection - P6 (a possible state of occurrence of discontinuity defects, reasons for reducing the resource of laser equipment nodes); when the asymmetry of signals from the geometry of the joint, the seventh for exceeding the edges - P7 and eighth for deviations from the joint - P8 and / or from the angle between the parts and the laser beam - P8.1; the ninth for exceeding the level of the joint gap - P9; tenths for the causes of abnormal conditions from violations of gas protection - P10.1, P10.2 (respectively, signals of sensors 9, 10); eleventh for the causes of abnormal conditions of penetration from a decrease or exceeding the level of laser radiation intensity - P11.1, P11.2 (respectively, according to the signals of the sensor 7); twelfth, thirteenth and fourteenth for the causes of abnormal penetration states from temporary penetration parameters - P12.1, P12.2 and P13.1, P13.2 (respectively for the pump duration and for the pump frequency according to the signals of block 3), as well as P14. 1, P14.2 (for the relative speed of the laser beam 13 and the parts to be welded 14 according to the signals of the transducer 18); fifteenths to control the reasons for the decrease or excess of the level of laser radiation intensity from changes in the amplitude of the pump current - P15.1, P15.2 (respectively, according to the signals of sensor 3); sixteenth for monitoring the life of the laser unit from abnormal changes in the temperature of the cooling medium - P16 (respectively, according to the signals of the sensor 5).

Thresholds P2 and P3 correspond, taking into account tolerances, to going beyond the limits of the norm to the side of lack of penetration and overheating. For P2 and P3, when compared with the source signals, control thresholds for PCs are assigned. And the prediction thresholds for them correspond to the comparison with the IgES values additionally differentiated in block 20. Thresholds for monitoring Pc of emissions of Pv also correspond to the IES values additionally differentiated in block 20.

In the work, the initial signals of the IRI of the thermal traces of the diagnosed objects from the corresponding zones are visualized by the optical input of the transducer 18. In this case, the spatio-temporal signals of infrared radiation of the thermal traces on the surface of the parts being welded 14 are measured in the visible area of the laser radiation 13, in the focus areas of the laser beam 15 and its heat waves 16. Here, the sighted signals of the IKI are converted into electrical transducers with point surface heat-sensitive elements to obtain m from each of them an electric signal Andi, where i is the number of the element.

The conversion of temporal, spatial changes in the amplitudes of the source signals to the gradient-extreme IgES signals is carried out by accumulation and blur, modeled by the differential heat equation at various stages of operation, depending on the design of the converter 18 and blocks 19-20 as follows.

The initial thermal traces of the diagnosed objects for the transducer 18 can be represented as point, one-, two- and three-dimensional, reduced to two-dimensional sections; various characteristics of area and geometry; predominantly invariant to scale and position in the image field.

For them, the model of basic transformations has the form:

when conditionally static for the time of the high-speed implementation (1) of the task domain with the conversion coefficient k of the signals of the original image E (x, y) into the signals of the converted image I (x, y) with coordinates x, y.

The uniqueness of the basic model (1) is determined by the initial conditions Io = E (x, y) and, within the boundaries Ho-Xg, Yo-Yg, by the boundary conditions ∂IG / ∂n = 0

Coefficients a, b with their derivatives, respectively, simulate the accumulation, blurring of signals. Thus, taking into account the coefficients a, b, k, one can tune out from small-sized, pulsed noise at the initial E (x, y) in time t.

The considered filtering transformation (1) allows one to significantly detune from changes in the emissivity of the IRI, from non-informative changes in heat transfer and from non-informative changes in the thermophysical characteristics of materials, as well as from small-sized short-term interference. These changes, if there were no transformations (1), in the aggregate and each separately, could significantly distort the results of thermal monitoring of the IKI.

Implementation of the transformation (1) in various ways increases the flexibility of providing universal capabilities of the device 17. Thus, the transformation (1) with high speed and simple software and technical implementation can be obtained in the converter 18 and block 19 using the convolution integral. Those. using well-known methods and hardware for optical and electronic defocusing. In this case, optical defocusing can be realized by the input optical nodes in the transducer 18. However, it is associated with the introduction of only a Gaussian defocusing transform. Equivalent to defocusing, optical correlation using defocusing masks can be more versatile and faster, but related to the relative complexity of the filters.

It is also possible to implement methods of digital, analog, quasi-analog (equivalent by results) modeling using finite-difference approximation, using the fundamental solution of Kelvin and others.

For complex noisy information arrays, a universal software computer or specialized software microprocessor implementation in block 20 of the basic model (1) allows gradient-extreme transformations to be performed with increased accuracy and efficiency using the patterns of accumulation and blurring of accumulated signals.

The initial E (x, y), usually representing signals of thermal changes in region 16, in blocks 18-20 are converted by means of (1) into gradient-extreme IgES (x, y) with an informative representation of the amplitude and area of the initial effect.

In block 20, threshold comparisons of IgES signals from transducer 18 and signals from sensors 3, 5, 7, 9, 10 and thresholds P1-P18 are performed. This ensures tracking of the threshold mismatch, diagnose the condition of the welded joint parts 14 and a possible decrease in the resource characteristics of the blocks of the laser welding installation.

In block 20, the IgES signals from zones 15.16 of the welded parts 14, having passed the transducer 18 and block 19, are first compared with the threshold P1.

The signal of the presence of the welding process is determined by equality or excess by the total signal And _Σ (IES), from all the thermosensitive elements of the temperature sensor in the converter 18, of the first threshold value P1.

By counting the signals of the presence of the welding process and comparing them with benchmarks, the number of the welding point, the current position, the length of the seam or the passage of penetration are identified.

Similarly, in block 20, by comparing And _Σ with thresholds P2, P3, non-standard states of the welding process are determined according to a given welding technology. Including, for lack of penetration by equality or decrease relative to the second threshold value of P2, and for overheating by equality or exceeding the third threshold value of P2 by the total signals And _Σ . So, they analyze the amplitudes And _{Σ of} gradient-extreme signals of non-standard sizes of the weld pool by threshold monitoring according to PC to control the occurrence of diagnosed states and according to PPR to control the temporary derivatives ∂I _Σ / ∂t of the possibility (forecast) of their occurrence. Moreover, when comparing with Ppr, the forecast signal allows you to regulate in time, for example, the pump current supply in block 2 by the signal of the circuit of blocks 20, 19, 12, in many cases preventing lack of penetration, and on the other hand preventing overheating. Excluding overheating, in some cases its consequences are eliminated, such as an abnormal increase in penetration, discontinuity defects, concentration of residual stresses, thermal deformations of the welded structure, and emissions of molten material.

Differentiated IgES signals that passed the transducer 18, block 19 in block 20 help to control significantly shorter durations of the welding current than the emission signals of molten material. Outliers are detected by selection of nonmonotonic maxima of their peaks. Thus, in block 20, by comparing the time derivative of the total signal ∂I _Σ / ∂t with the emission threshold Pv, non-standard emission conditions of the molten material and its type, burn-through, are determined according to the specified welding technology. This is done by the equality or exceeding ∂IΣ / ∂t of the threshold values of emissions of PV.

Just as the normalization control and the provision of adaptive control of nominal penetration is carried out according to the signals of the circuit blocks 14, 18-20, 12 for a given technology of sighting and signal processing, violations of the geometry of the seam along an uneven width, gain along the length, and also sagging of the root of the seam are determined.

In block 20, the signals of the chain of blocks 14, 18-20, respectively, of the specified welding technology determine the occurrence of discontinuity defects, reasons for reducing the resource of laser equipment nodes (by the equality or exceeding by the total signal And _Σ from block 18, the sixth threshold value P6).

Thus, in blocks 18, 19, 20, the diagnosis of gradient-extreme IgES signals of the main non-standard states of quality of the laser welding process is implemented.

In block 20, according to the signals of the chain of blocks 14, 18-20, the navigation characteristics of the motion control are determined according to the specified welding technology by comparing Andi of the corresponding areas of sight of the butt for the tack with the fourth P4 for the closed edge of the seam with the fifth P5, for the open edge with zero P0 the corresponding threshold values .

Similarly, but taking into account signals from the asymmetry of the geometry of the joint in block 20, the excess of the edges (by exceeding the threshold P7), deviations of the laser beam from the joint between the welded parts (by exceeding the threshold P8) and / or from the angle between the parts and the laser beam (by exceeding the threshold P8.1), exceeding the level of the joint gap (by exceeding the threshold P9). This is done by amplitude selection of the signals of the parts to be welded, which are sighted according to the given welding technology in front, on the sides of the joint path or relative to the axis of the laser beam. Moreover, for comparable welding technologies, the threshold differences of the signals And deviations when the edges are exceeded (by exceeding the threshold P7) are less than the threshold differences of the signals And i deviations from the butt (by exceeding the threshold P8), and also usually from the angle between the parts and the laser beam (when exceeding threshold P8.1).

Moreover, if the laser beam 13 deviates from the joint, then in front of and on the lateral sides in the direction of travel the thermal symmetry of the signals And relative to the heat-separating joint is violated. The optoelectronic heating channel, sighted by the transducer 18, perceives a thermal signal of this asymmetry. In block 20, a signal is generated that exceeds threshold P8, which corresponds to the magnitude and direction of the deviation. It is transmitted to block 12, closing the feedback of the adaptive control, and eliminating thermal mismatch by block 11 (processing the feedback signal) and returning the laser beam 13 to the joint.

The excess of the edges is also associated with the violation of the thermal symmetry of the signals And relative to the heat-separating joint and is determined by exceeding the threshold P7.

The deviation of the laser beam 13 from the normalized values of the angle, especially during angular welding, can lead to significantly greater than deviations from the junction of thermal asymmetry. This is monitored by comparison with the threshold P8.1.

Significantly reduced IgES signals with an increase in the joint gap, which determines a comparison with the threshold P9. In this case, an unacceptable size of the joint gap of the welded parts is identified by threshold control of a decrease in the amplitudes of signals And thermal traces of penetration of the heat-sensitive element sighted at the joint.

In software, in block 20, an unacceptable joint gap of the parts to be welded is identified as a fact or a possible cause of lack of penetration and related defects of discontinuity, in the absence of other causes of lack of penetration.

By the signal of the end of welding from block 12, the signals of the open or closed edge of the seam in block 20, the number of the welded seam is identified according to the specified welding technology. Then, in block 20, the number of the welded product is identified by the number of welded seams and / or seam lengths.

Identify the reasons for the actual or possible occurrence of discontinuity defects and a decrease in the resource of laser equipment components from violations of the supply and suction of the protective gas mixture in the welding zone by the appearance of electrical signals of equality or decrease relative to threshold levels P10.1, P10.2 in the circuits of blocks 20-19-9 and 20-19-10 for sensors for blowing 9 and / or exhaust 10. In addition, another reason for reducing the life of laser equipment is the appearance in the circuit of blocks 20-19-5 of signals of threshold or pre-threshold levels of unacceptable excesses temperatures characterizing abnormal forced modes and malfunctions in block 6 during the formation of the required laser exposure. Similarly, by monitoring thermal anomalies, malfunctions in blocks 2, 8, 11, 12 are detected.

In block 20, the actual or pre-threshold comparisons are identified as possible causes of lack of penetration: by the appearance in the block circuit of 18-20 signals of threshold or pre-threshold levels of unacceptable edge excesses (by exceeding or equal to threshold P7), deviations from the joint (by exceeding or equal to threshold P8), from the angle between the parts and the laser beam (by exceeding or equal to the threshold P8.1); by the appearance in the circuit of blocks 7, 19, 20 of signals to reduce the level of laser radiation intensity (when the signal is less than or equal to the threshold P11.1); by the appearance of signals of the chain of blocks 3, 19, 20 of decreasing amplitude (when the signal is less than or equal to the threshold P15.1), duration (when the signal is less than or equal to the threshold P12.1), frequency (when the signal is less than or equal to the threshold P13.1) of signals laser pump current; by the appearance in the circuit of blocks 18-20 of signals for increasing the welding speed (when the signal is greater than or equal to the threshold P14.1); by unacceptable changes in the magnitude of the laser spot (comparison, depending on the welding technology, with threshold P17) for signals in the circuit of blocks 18 - 20. In this case, changes in the level of laser energy and power are determined by monitoring in block 6 with a sensor 7 the laser radiation intensity at a wavelength laser exposure to the material. Or, by monitoring the sensor 3 of the laser beam pump current in block 2. In block 20, an unacceptable joint gap of the welded parts is identified as a fact or a possible cause of lack of penetration, related defects of discontinuity, in the absence of other causes of lack of penetration. Or by threshold control in a chain of blocks 18-20 to reduce the amplitudes of signals And thermal traces of penetration of the heat-sensitive element sighted at the joint.

Identify the actual or pre-threshold comparisons of the possible causes of overheating, emissions by the appearance of threshold or pre-threshold levels of unacceptable excesses: in the circuit of blocks 20-19 - a sensor 7 of laser radiation intensity signals (A11.2); in the circuit of blocks 20-19 - a sensor 3 of signals of amplitude (A15.2), duration (A12.2), frequency (A13.2) of the laser pump current; in the chain of blocks 18-20 signals to reduce the welding speed (P14.2) and unacceptable changes in the magnitude of the laser spot (P17) for signals in the chain of blocks 18-20. In this case, unacceptable changes in the magnitude of the laser spot are identified as a fact or a possible cause of the diagnosed states of lack of fusion or overheating, emission, by establishing in block 20 the absence of other causes of these diagnosed conditions.

In block 20, according to the specified welding technology, the considered signals of unacceptable penetration conditions, their actual or possible reasons for real-time correction of the welding process or correction of the defective area by re-melting or stopping the process during a long-term violation of the optimal welding process are recorded. Signals are also generated for automatic control of the laser welding process by adaptively changing the amplitude, laser pump duration, welding speed, pulse frequency, and laser radiation focusing.

At the same time, in order to eliminate the technological causes of lack of fusion, overheating, and emissions in simple versions of the developed technology, it is sufficient to adaptively control the supply current in block 2 through the circuit of blocks 20-19-12, since the passage of current only with temporary adaptation to eliminate lack of fusion and overheating then impacts are used to eliminate the other technological reasons considered.

The considered operations in the device 17 provide adaptive control along the main signal chain, the parts to be welded 14 are blocks 18-20, 12. The technology tolerances for mismatch and poor-quality preparation of edges, for changes in the gap, for deviations from the joint, for the amount of sagging of the weld root are taken into account. on deviations of the modes of formation of laser exposure by the beam 13 of the installation 1 on the materials being welded 14.

Thus, the main technical result obtained consists in a substantial expansion of the diagnostic capabilities, quality control of laser welding and in improving the technological reliability of the process in real time. Informative comprehensive causal relationships of signals reflecting the dynamics of the main elements of the laser welding process have been more fully determined.

Diagnostics of the appearance of discontinuity defects and causes of a decrease in the resource of laser equipment nodes have been added to the main diagnosed states.

Diagnostics of the causes of all abnormal conditions has been introduced. Including for abnormal characteristics: laser energy; amplitude, duration and frequency of the pump current; welding speed; laser focusing; coolant temperature; gas protection.

In monitoring the geometry of the joint, added control over the excess edges, and control over the gap.

Amplitude control, duration control, and pump current frequency control are added to the characteristics of penetration energy tracking.

Welding speed control has been added to the characteristics of tracking the temporary parameters of penetration.

To the characteristics of monitoring the decrease in the resource of laser equipment nodes, control over gas protection and control over the temperature of the cooling medium have been added.

This was achieved by systemic synthesis of various control channels, including additional ones according to the pump current, energy and focusing of the laser beam, temperature of the cooling medium, and gas protection. A single complex of parallel diagnostics of the main conditions of penetration, the appearance of discontinuity defects and a decrease in equipment life, analysis of the causes of non-standard penetration is provided. The causes of abnormal conditions are eliminated during tuning, timely repair, adaptive real-time adjustment of the quality of laser welding, taking into account the geometry of the joint, energy and temporary parameters of penetration, gas protection and temperature of the cooling medium.

The considered thermosensor diagnostics of the formation of the seam and the operation of equipment of laser welding processes with the provision of adaptive control is not limited to the described description of laser welding. It is possible to use for various modes, materials, thicknesses, technologies (including butt, corner, lap, orbital), with the additive, in the environment of various protective gases and without it, in any spatial position of laser welding.

At the same time, they work out the minimum required mismatches without the participation of the operator, with optimization of the dynamics of oscillations of the electric drive. The reliability of the welding installation is increased, the complexity is reduced, the productivity is increased (automated tuning, the use of intensive modes, the reduction in the duration of the start of the welding process), and welding materials and energy are saved. The spraying of the material is reduced, the accuracy and stability of the process, i.e. quality of welded joints improves.

Claims (11)

1. A method for diagnosing and controlling the quality of welding, including the measurement of spatio-temporal signals of infrared radiation of thermal traces on the surface of welded parts in the visible areas of the effects of the welding tool and its heat waves, the conversion of temporary, spatial changes in signal amplitudes into gradient-extreme signals by means of simulated differential equation thermal conductivity of accumulation and blur, conversion of infrared radiation into informative electric signals from a transducer with point surface thermosensitive elements of a temperature sensor to receive an electric signal Ii from each of them, where i is the element number, determining the relative deviations of the welding tool from the joint between the parts to be welded and / or from the angle between the parts and the axis of the welding tool by amplitude selection of signals And parts to be welded, sighted according to a given welding technology in front, on the sides of the joint path or relative to the axis of the welding tool and using the sighted surface region of the heat penetration wave, determining the presence of the welding process when the first threshold value is equal or exceeding, determining the lack of penetration when the equality or decreasing relative to the second threshold value, determining the overheating when the third threshold value is equal or exceeding for the total signals And _Σ from all heat-sensitive elements temperature sensor, determination of the emission of molten material in case of equality or exceeding the threshold values of emissions for temporary production of the total water signal ∂I _Σ / ∂t, determining the navigation characteristics of motion control by comparing And _{Σ of the} corresponding areas of sight of the joint for the tack with the fourth, for the closed edge of the seam with the fifth, for the open edge with zero threshold values, respectively, of the specified welding technology, characterized in that they carry out diagnostics and quality control of laser welding, for which a laser beam is used as a welding tool, while the number of the welding point, the current position, the length are identified VA or pass through the penetration by counting the signals of the presence of the welding process and comparing them with benchmarks, identify the number of the welded seam by the signal of the end of welding, or by the signal of the open edge of the seam, or by the signal of the closed edge of the seam according to the specified welding technology, identify the number of the welded item the number of welded seams and / or seam lengths, determine the possibility of the appearance of discontinuity defects and reasons for reducing the resource of laser equipment units for a given welding technology ki by equality or exceeding the sixth threshold value by the total signal And _Σ , determine the excess of the edges of the parts to be welded by threshold amplitude selection of the signals Andi of the parts to be welded, sighted accordingly to the specified welding technology in front and on the sides of the joint path, identify the actual or pre-threshold comparisons of possible causes of lack of penetration by the appearance of signals of threshold or subthreshold levels of unacceptable edge excesses, deviations from the joint, gap size, level reductions laser radiation intensity, amplitude, duration, frequency of laser pump intensity signals, increase in welding speed and unacceptable changes in the laser spot value, identify the actual or pre-threshold comparisons of possible causes of overheating and emissions by the appearance of signals of threshold or pre-threshold levels of unacceptable excesses of laser radiation intensity, amplitude, duration, frequency of laser pump intensity signals, reduction of welding speed and unacceptable changes in values a laser spot, register, according to a predetermined welding technology, signals of unacceptable penetration states, their actual or possible reasons for real-time adjustments of the welding process, or re-melting of a defective area, or stopping a process during a long-term violation of the optimal welding process and generate signals for automatic control of the laser welding process by adaptive changes in amplitude, laser pump duration, welding speed, pulse frequency and focusing of laser radiation Nia. 2. The method according to claim 1, characterized in that it further determines the change in the level of laser power by controlling the intensity of the laser beam with an infrared radiation sensor. 3. The method according to claim 1, characterized in that it further determines the change in the level of laser power by controlling the pump current of the laser beam. 4. The method according to claim 1, characterized in that it determines the presence and cause of the change in the level of laser radiation intensity, the presence of changes in the duration and frequency of the laser pulses by controlling the pump current of the laser beam. 5. The method according to claim 1, characterized in that an unacceptable joint gap of the welded parts is identified in the presence of lack of fusion, concomitant discontinuity defects, in the absence of other causes of lack of fusion. 6. The method according to claim 1, characterized in that an unacceptable joint gap of the parts to be welded is identified by threshold control of a decrease in the amplitudes of signals Ii of thermal traces of penetration, while the heat-sensitive element is sighted at the joint of the parts to be welded. 7. The method according to claim 1, characterized in that the actual or possible causes of the appearance of discontinuity defects are identified, the resource of the laser equipment nodes for a given welding technology is reduced by deviations from the threshold levels of electrical signals from the sensors for blowing and / or exhaust of the protective gas mixture in the welding zone. 8. The method according to claim 1, characterized in that unacceptable changes in the magnitude of the laser spot are identified for the diagnosed states of lack of penetration, overheating, discharge in the absence of other causes of these diagnosed conditions. 9. A device for diagnosing and controlling the quality of welding, comprising a power supply unit, an infrared converter for visualizing the thermal trace of the impact of a welding tool on the materials being welded by the optical input, a control unit and an operation unit connected to the recorder by an output, characterized in that it is capable of diagnostics and quality control of laser welding, for which a laser beam is used as a welding tool, and it is equipped with a laser unit with a laser intensity sensor beam, a laser pump current sensor located in the power supply unit, and an electronic matching unit, while the operating unit is electrically connected to the input and output to an infrared converter through an electronic matching unit that is connected to the input and output of the control unit, the laser pump current sensor, and the sensor of the intensity of the laser beam, and the infrared transducer is made with the possibility of orientation along the areas of sight of the neighborhoods of surfaces located along the relative movement of the laser beam along the joint, in front and on the sides of the joint path or relative to the axis of the beam to control approaches to the weld seam, to the end of the weld of a solid metal of the closed edge and to the end of the seam of the edge of the open edge, the vicinity of the surface of the heat trace of the weld pool being formed, the vicinity of the surface focusing of the laser spot, the vicinity of thermal traces of the controlled surfaces of the laser block to diagnose their abnormal conditions and deviations. 10. The device according to claim 9, characterized in that it is equipped with a temperature sensor for the cooling medium located in the cooling unit of the laser unit and connected to the electronic matching unit. 11. The device according to claim 9, characterized in that it is equipped with blowing and exhaust sensors located in the gas protection unit of the laser unit and connected to the electronic matching unit.