A handheld laser welding head with monitorable and adjustable light spot and control method

Abstract

A handheld laser welding head and control method with a monitorable and adjustable light spot provide a technical solution for real-time monitoring of laser welding results and real-time adjustment of the light spot. This approach aims to create a device that is less susceptible to interference from the environment and other adverse factors, accurately detects reflected light from the welding head, and allows for timely adjustment of the welding device when the welding head encounters adverse or unexpected conditions.

Description

Technical Field

[0001] The present invention relates to a handheld laser welding head with monitorable and adjustable light spot and a control method, and in particular, provides a technical solution for achieving real-time monitoring of laser welding effects and real-time adjustment of light spots. Background Art

[0002] Handheld laser welding replaces the traditional fixed optical path with a handheld welding gun. It is an efficient and convenient precision welding technology that uses a high-energy-density laser beam as a heat source. The handheld laser welding head primarily uses optical lenses to shape and output the laser beam, making it a key component of laser welding equipment. Currently, common laser welding heads mainly use two solutions: galvanometer and rotary to achieve beam trajectory oscillation.

[0003] Currently, there are two technical solutions for handheld laser welding heads: a high-speed rotating wedge prism and an oscillating galvanometer. Both technologies can adjust the optical path and improve welding quality, but they also have drawbacks. First, they cannot effectively identify the welding effect. Second, the fixed trajectory of the beam swing makes it difficult to effectively adjust the beam according to the dimensional tolerance of the workpiece. Finally, the real-time change of the optical path also reduces the stability and safety of long-term operation.

[0004] Current existing technologies, such as CN112828442A, which uses a swing motor to drive a reflector, cannot effectively identify the welding effect for adjustment and improvement. Existing technologies for real-time diagnosis and adjustment of welding effects, such as CN214558228U, CN110340552A, and CN109297976A, only involve using sensors to detect reflected light and identifying welding effects through light intensity or energy models. This is only a fuzzy result of a complex process (the complex interaction between laser energy and the weld surface) to detect. Not only can the interference of environmental factors not be eliminated, but also the process cannot be detected and analyzed. Therefore, when an abnormality occurs, it is often difficult to accurately analyze its core cause. It is also impossible to accurately detect whether the laser energy during the welding process is stable and uniform to achieve adjustment. It is also impossible to timely detect abnormalities in the physical changes of the weld surface to prevent damage caused by unexpected changes to the weld surface. Consequently, it is impossible to provide more direct and rapid detection results of weld surface abnormalities.

[0005] Lasers are highly harmful to the human eye, and they can sometimes be reflected from surfaces and enter the human eye, causing unexpected damage. This can easily occur when weld penetration occurs during welding, the laser reaches irregular surfaces, or unexpected changes in the laser path occur during welding. Furthermore, if the welding process can be accurately analyzed and beam quality parameters and surface morphology identified, this allows for precise control of the welding process and immediate handling of unexpected situations. Summary of the Invention

[0006] In view of the deficiencies of the prior art, the present invention provides a handheld laser welding head with monitorable and adjustable light spot and a control method, which overcomes the deficiencies of the prior art and has a reasonable design.

[0007] Conventional detection of welding conditions solely through data such as reflected light intensity is subject to numerous interference factors and is susceptible to misjudgment due to environmental interference. Therefore, a detection system that is accurate, fast, and not susceptible to environmental interference is desired to assist welding machines. To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0008] An adjustable handheld laser welding head comprises a collimation system, a reflection system, a focusing system, a detection system, a control system, a laser output part and a laser driving system; the laser output part comprises a laser part for generating welding laser and an output optical fiber for outputting welding laser; the collimation system comprises a collimating mirror for shaping a divergent light beam output by the optical fiber into a collimated laser; the reflection system comprises a reflecting lens and a swinging motor, the reflecting lens can swing inward under the control of the swinging motor to achieve trajectory swing of the collimated light beam; the focusing system comprises a focusing lens for focusing the collimated laser beam; the detection system comprises one or more photoelectric sensors for detecting reflected light; the control system comprises a data processor and a controller, the data processor processes the electrical signal output by the photoelectric sensor, and the controller controls the swinging motor and / or the laser output driving system of the reflecting system according to the processing result signal output by the data processor; the laser driving system is used to drive the welding laser to be output from the laser output part, and can drive the laser output part to output the welding laser by receiving the signal output by the control system.

[0009] Preferably, the detection system obtains the reflected light intensity data after the start of laser welding, the control system analyzes the waveform of the reflected light intensity data, and the control system controls the swing motor and / or laser output drive system of the reflection system according to the waveform of the reflected light signal intensity detected by the photoelectric sensor that changes with time.

[0010] Preferably, in the reflected light intensity waveform of the photoelectric sensor, when the first falling edge width or the second falling edge width is smaller than a second preset width value, the laser power density is reduced by the control system.

[0011] Preferably, in the reflected light intensity waveform of the photoelectric sensor, when the first falling edge width or the second falling edge width is greater than a third preset width, the laser power density is increased by the control system.

[0012] Preferably, the laser power density is reduced by increasing the swing angle of the swing motor in each direction as needed, or the laser power density is increased by decreasing the swing angle of the swing motor in each direction as needed.

[0013] Preferably, when the first falling edge width or the second falling edge width of the reflected light intensity signal waveform of the photoelectric sensor is lower than the second preset width value, the power density of the welding laser is reduced, the laser output power of the laser output part is reduced and / or the swing angle of the swing motor in each direction is increased within the first range.

[0014] Preferably, when the first falling edge width or the second falling edge width of the reflected light intensity signal waveform of the photoelectric sensor is less than the first preset width, the controller immediately turns off the laser; or, when the output power of the laser driving system 7 driving the laser to work is greater than the first predetermined power value and less than the second predetermined power value, the first predetermined power value is less than the second predetermined power value, and when the output power of the laser is between the first predetermined power value and the second predetermined power value, when the reflected signal detected by each photoelectric sensor is lower than the first preset reflection intensity threshold, the controller controls the laser welding equipment to turn off.

[0015] Preferably, it includes 4 photoelectric sensors, which are respectively located in the four directions of +x, +y, -x, and -y on the radial direction of the light transmission path. The control system includes a data processor and a controller. The data processor processes and integrates four electrical signals. The controller controls the swing motor according to the difference in waveform intensity of each photoelectric sensor and the conversion relationship between the electrical signal amplitude of each photoelectric sensor and the swing angle of the reflector in each direction, and corrects the swing amplitude of the reflector in the corresponding direction to achieve uniformity of the light spot.

[0016] Preferably, it includes 4 photoelectric sensors, which are respectively located in the four directions of +x, +y, -x, and -y on the radial direction of the light transmission path. The control system includes a data processor and a controller. The data processor processes and integrates four electrical signals, and controls the swing motor accordingly according to the conversion relationship between the width of the falling edge of the reflected light intensity waveform of each photoelectric sensor and the swing angle of the reflector in each direction, and corrects the swing amplitude of the reflector in the corresponding direction to achieve uniformity of the light spot.

[0017] Preferably, in continuous welding mode, when the energy density of the weld point needs to be stabilized, when the width of the first falling edge or the second falling edge of the sensor in the i-th cycle obtained by the processor is within a first set range, the processor does not issue an instruction to change the laser power or the swing angle; when the width of the first falling edge or the second falling edge obtained by the processor is greater than the upper limit of the first set range, the processor increases the laser output power of the laser output part 6 and / or decreases the swing angle of the swing motor in the corresponding direction until the width of the first falling edge or the second falling edge in the i+m-th cycle is within the first set range; when the width of the first falling edge or the second falling edge obtained by the processor is less than the lower limit of the first set range, the processor decreases the laser output power of the laser output part and / or increases the swing angle of the swing motor in the corresponding direction until the width of the first falling edge or the second falling edge in the i+n-th cycle is within the first set range. A control method for a handheld laser welding head with adjustable spot monitoring includes a handheld laser welding head that is regulated according to the waveform of the reflected light signal intensity varying with time, and a controller that controls the laser output intensity and / or the swing angle of the swing motor according to the waveform of the reflected light signal intensity varying with time.

[0018] The invention provides a handheld laser welding head with monitorable and adjustable light spot and a control method.

[0019] The present invention has the following beneficial effects: It adds a photoelectric sensor to the handheld galvanometer laser welding head. First, by receiving return light signals at four angles, the welding effect of the workpiece can be monitored in real time. Second, when the photoelectric detector detects fluctuations or abnormalities in the waveform of the return signal, the control system can control the motor according to the signal waveform, adjusting the swing amplitude and frequency of the optical lens accordingly to even out the weld spot and enhance the welding effect. Finally, when the intensity of the return light signal exceeds a set threshold range, it can be determined that the welding state is abnormal or the light output state is abnormal. The laser welding equipment automatically alarms and shuts off the light to protect the safety of the operator and the equipment.

[0020] By adding multiple photoelectric sensors to the welding head to receive the returned light signals from the workpiece, the amplitude of each signal and the changing speed of the falling edge are detected. The conversion relationship between the signal amplitude, the falling speed and the oscillation angle of the galvanometer can further realize the adjustment of the oscillating amplitude and frequency of the oscillating galvanometer, or the timely shutdown of the laser equipment, so as to achieve the purpose of optimizing the welding effect and protecting the safety of personnel and equipment.

[0021] This solution can achieve real-time control of the swing amplitude and frequency of the oscillating galvanometer, thereby improving welding effect and stability. A plurality of reflected light intensity detectors are provided, which may include 4 photoelectric sensors located in the four directions of +x, +y, -x, and -y on the plane. The control system includes a data processor and a controller. The data processor processes and integrates four electrical signals. The controller controls the oscillating motor accordingly according to the difference in waveform intensity of each photoelectric sensor and the conversion relationship between the electrical signal amplitude or falling edge width of each photoelectric sensor and the swing angle of the oscillating mirror (reflector) in each direction, and corrects the swing amplitude of the reflector in the corresponding direction to achieve uniformity of the light spot. Preferably, the conversion relationship between the electrical signal amplitude (or falling edge width) of the photoelectric sensor and the swing angle of the reflector in each direction can be calculated by preset data, a preset program, or an adaptive algorithm.

[0022] This solution can monitor abnormal signals of the returning laser in real time, feed back to the control system, and shut down the laser equipment in time to protect the safety of operators and processing equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for describing the prior art.

[0024] Figure 1 It is a structural schematic diagram of the welding head of the present invention;

[0025] Figure 2 is a schematic diagram of a photoelectric sensor of the present invention;

[0026] Figure 3 It is a schematic diagram of the control process of the present invention;

[0027] Figure 4 This is the waveform of the photoelectric sensor in pulse mode;

[0028] Figure 5 It is the waveform diagram of the photosensor in continuous mode. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solutions and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the present invention.

[0030] The embodiment of the present invention provides a handheld laser welding head with monitorable and adjustable light spot and a control method.

[0031] A handheld laser welding head with monitorable and adjustable light spot mainly comprises a collimation system 1, a reflection system 2, a focusing system 3, a detection system 4, a control system 5, a laser output part 6 and a laser driving system 7.

[0032] The collimation system 1 includes a collimating lens, which shapes the divergent light beam output by the optical fiber into a collimated laser.

[0033] The reflective system 2 includes a reflective mirror and an oscillating motor. Under the control of the oscillating motor, the reflective mirror can oscillate slightly within a two-dimensional plane at a certain oscillation frequency and amplitude to achieve oscillation of the trajectory of the collimated light beam. Preferably, the reflective system 2 includes a oscillating motor drive unit for driving the oscillating motor. The oscillating motor drive unit can be controlled by receiving a signal output by the control system. The oscillating motor drive unit drives the oscillating motor to achieve adjustment of the oscillation amplitude and frequency of the reflective mirror.

[0034] The focusing system 3 includes a focusing lens for focusing the collimated laser beam on the workpiece and converging the return light to the photodetector.

[0035] The detection system 4 includes one or more photoelectric sensors, preferably multiple, preferably four. To more accurately detect welding results, the four photoelectric sensors are preferably symmetrically and equally spaced toward the laser welding nozzle. Preferably, a photoelectric detector equipped with a focusing lens and optical filter is employed. It converts optical signals into electrical signals and transmits them to the control system. Furthermore, the specifications, number, placement, and angle of the photoelectric sensors can be further optimized based on the required detection accuracy and the actual intensity of the reflected light. Preferably, it also includes a reflected light signal processing unit that processes and analyzes the light intensity signals measured by the photoelectric sensors. The signals acquired by the detection system can be output to the controller in the laser drive system.

[0036] The control system 5 includes a data processor and a controller. The data processor processes and integrates the electrical signals output by the multiple photoelectric sensors. The controller controls the swing motor of the reflective system and / or the laser output drive system 7 based on the processing result signals output by the data processor. Preferably, in addition to outputting the light intensity waveform data or intensity analysis data of the multiple individual photoelectric sensors, the data processor can also preferably output the overall light intensity waveform data or intensity analysis data of the comprehensive analysis.

[0037] The laser output section 6 includes a laser section for generating welding laser light and an output optical fiber for outputting the welding laser light.

[0038] The laser driving system 7 is used to drive the welding laser to be output from the laser output part 6. It can drive the laser output part 6 to output different welding lasers by receiving the signal output by the control system, that is, the laser driving system 7 can drive the laser output part 6 to output welding laser, or the laser driving system 7 can drive the laser output part to output welding lasers of different intensities and / or different modes.

[0039] The inventors discovered during the welding process that, as the welding laser acts on the workpiece, the workpiece exhibits certain physical changes. Specifically, when the welding laser begins acting on the workpiece, the workpiece's surface reflectivity and reflected laser light intensity decrease as the workpiece temperature rises to its melting point. During the melting phase, the workpiece's surface reflectivity and reflected laser light intensity stabilize, and after reaching the metal's boiling point, the reflected light intensity decreases again. Therefore, the inventors realized that if a stable photoelectric sensor is used to detect reflected light, the reflected light intensity signal P(t) detected by the sensor should exhibit three trends over time: decreasing, unchanged, and decreasing. The rate of change of the reflected light intensity signal P(t) is primarily determined by the laser power density. The three-stage trend of the reflected light intensity signal P(t), i.e., the rate of change of the falling edge during the decreasing, unchanged, and decreasing phases, is primarily determined by the laser power density. This pattern should be observed at the start of each welding process.

[0040] See also Figure 4 It can be seen from the figure that the reflected light intensity signal P(t) shows an upward trend from the time of light on to t1 (i.e., the first rising section), and reaches its maximum value at t1. At this time, as the workpiece temperature rises to the melting point, the workpiece surface reflectivity and the reflected laser light intensity decrease, and P(t) begins to decrease with time. Between t1 and t2, P(t) shows a downward trend, that is, the reflected light intensity signal curve of P(t) from t1 to t2 is the first falling edge; after reaching t2, During the melting process, the workpiece surface reflectivity and the reflected laser intensity tend to be stable, and P(t) remains basically unchanged until time t3. Between time t2 and time t3, the curve of the reflected light intensity signal P(t) is the first stable section; after time t3, the welding area reaches the metal boiling point. After reaching the metal boiling point, the reflected light intensity drops again. Between time t3 and time t4, the reflected laser intensity P(t) shows a downward trend, that is, the reflected light intensity signal curve of P(t) from time t3 to time t4 is the second falling edge.

[0041] See also Figure 4 In pulse mode, after the second falling edge ends, that is, after time t4, the laser welding process is basically over. At this time, the welding light output can be set to end, that is, the pulse ends, and the reflected light intensity gradually disappears.

[0042] See also Figure 5In the continuous welding mode, there are multiple welding cycles. At each welding point (welding cycle), the reflected light intensity signal P(t) shows an upward trend from the beginning of the cycle to time t1 (i.e., the first rising section). At time t1, P(t) reaches the maximum value within the cycle. At this time, as the workpiece temperature rises to the melting point, the workpiece surface reflectivity and the reflected laser light intensity decrease, and P(t) begins to decrease with time. Between time t1 and time t2, P(t) shows a downward trend, that is, the reflected light intensity signal curve of P(t) from time t1 to time t2 is The first falling edge; after reaching time t2, the workpiece surface reflectivity and the reflected laser light intensity tend to stabilize during the melting process, and P(t) remains basically unchanged until time t3. Between time t2 and time t3, the curve of the reflected light intensity signal P(t) is the first plateau; after time t3, the welding area reaches the metal boiling point. After reaching the metal boiling point, the reflected light intensity decreases again. Between time t3 and time t4, the reflected laser light intensity P(t) shows a downward trend; that is, the reflected light intensity signal curve of P(t) from time t3 to time t4 is the second falling edge. At time t4, the welding enters the next welding position, that is, the next welding cycle. Each cycle repeats like this, including the first rising segment-first falling edge-first plateau-second falling edge.

[0043] The inventors also realized that the smaller the galvanometer (reflector) swing amplitude, the smaller the spot size, the greater the laser power density, the faster the metal's refractive index decreases as the surface temperature rises, and the faster the return light power detected by the photodetector decreases. Therefore, the galvanometer's swing amplitude is also preferably used as a reference factor and adjustment method for detecting the reflected light signal, allowing for comprehensive and accurate evaluation of the laser welding condition and corresponding, precise adjustment of the welding light effect as needed.

[0044] Therefore, in addition to being able to adjust according to the intensity of the reflected light signal, it can also be regulated according to the waveform of the reflected light signal intensity that changes with time. The controller in the laser drive system 7 can control the output light intensity of the laser and / or the swing angle of the swing motor according to the waveform of the reflected light signal intensity that changes with time.

[0045] For example, in a conventional detection feedback adjustment light source system, if it is detected that the intensity of the reflected light intensity signal of each photoelectric sensor is too low (for example, when the reflected light intensity signal is less than a first predetermined value), the output energy of the laser can be increased by the controller of the laser drive system 7 for adjustment.

[0046] In a preferred embodiment of the present application, in addition to providing corresponding feedback after detecting that the reflected light intensity signal is too low, corresponding adjustments can also be made by analyzing the waveform of the emitted light intensity signal. For example, in the reflected light intensity waveform of each photoelectric sensor, when the falling edge is too wide (the falling edge width is greater than the first preset width value) or the falling speed is too slow (the falling speed is lower than the first preset speed), it basically means that the laser power density is low, and the laser power density can be increased by the control system. (The reflected light intensity signal is affected by many factors, and as an absolute signal value, it often cannot reflect the most accurate situation. Parameters such as the falling edge width and the relative proportion of the falling edge are used as relative change values. Because they have the data of the previous or next similar time period as a benchmark, the overall background influencing factors of the reflected light intensity signal waveform are basically consistent, which can filter out noise caused by some complex environmental factors and improper operation factors.)

[0047] For the same welding material, the lengths of the two falling edges are similar. If the power density is low, the widths of the two falling edges will become longer, and the widths of the two falling edges will be approximately the same. Under the same laser power density, due to the approximate linear relationship, the falling edge speed and the falling edge width should be inversely proportional. The power density can be measured by a single parameter, the falling edge speed and width. Here, we preferably use the falling edge width to measure the power density. Generally, in ordinary welding processes, the width of the first falling edge / second falling edge is on the order of tens of microseconds to hundreds of microseconds. The higher the laser power at the welding point, the narrower the falling edge width, and the lower the laser power at the welding point, the wider the falling edge width. The usual reasonable range can preferably be preset to, for example, 30 microseconds to 700 microseconds, or 50 microseconds to 500 microseconds.

[0048] When the power density needs to be increased, although the output power of the welding laser can be increased, sometimes when the laser output power is high, it is possible that the temperature near the welding point will rise too high, causing the molten pool to become larger, and ultimately resulting in a larger welding area, affecting the workpiece structure in the non-welding area. At the same time, the expansion of the welding range will be detrimental to the processing of small parts. In order to solve this problem, the inventor realized that the swing angle of the swing motor in each direction can be appropriately reduced as needed. This not only increases the laser power density and the welding speed, but also solves the problem of molten pool expansion caused by excessive temperature.

[0049] At the same time, by analyzing the waveform of the emitted light intensity signal, if it is found that the falling rate of the reflected light intensity signal waveform of each (certain) photoelectric sensor is higher than a second preset value, that is, the first falling edge / second falling edge width is less than the second preset width, it is determined that the power density of the welding laser needs to be reduced. The laser output power of the laser output portion 6 can be reduced, or the swing angle of the swing motor in each (certain) corresponding direction can be increased within the first range. Preferably, the second preset width can be set to 100 microseconds, or, more preferably, the second preset width can be set to 50 microseconds.

[0050] Furthermore, when the falling rate of the reflected light intensity signal waveform of each photoelectric sensor is found to be higher than a first set threshold, i.e., the width of the first falling edge / second falling edge is less than a first preset width, it can be determined that the energy density of the currently emitted laser is too high, and the controller can be caused to immediately shut down the laser to prevent the laser from welding through the workpiece. Preferably, the first preset width can be set to 10 microseconds, or preferably, the first preset width can be set to 5 microseconds, or preferably, the first preset width can be set to 1 microsecond.

[0051] During the welding process, a uniform welding laser energy density is often required. Therefore, multiple reflected light intensity detectors are set up, preferably including at least 3 or more photoelectric sensors, preferably including 4 photoelectric sensors. The control system includes a data processor and a controller. The data processor processes and integrates four electrical signals. The controller controls the swing motor according to the difference in waveform intensity of each photoelectric sensor and the conversion relationship between the electrical signal amplitude of each photoelectric sensor and the swing angle of the galvanometer (reflector) in each direction, and corrects the swing amplitude of the reflector in the corresponding direction to achieve uniformity of the light spot.

[0052] Preferably, four photoelectric sensors can be provided, and the four photoelectric sensors have four directions, such as +x direction sensor, +y direction sensor, -x direction sensor, and -y direction sensor. To adjust the swing angle of the reflector, it is only necessary to adjust the swing amplitude of the reflector in these four directions. The sensors in the four directions correspond to the swing angles in the four directions, that is, when the swing amplitude of the reflector is adjusted according to the reflected light intensity signal obtained by the +x direction sensor, the swing angle of the swing direction corresponding to the +x direction sensor is adjusted; that is, when the swing amplitude of the reflector is adjusted according to the reflected light intensity signal obtained by the +y direction sensor, the swing angle of the swing direction corresponding to the +y direction sensor is adjusted; that is, when the swing amplitude of the reflector is adjusted according to the reflected light intensity signal obtained by the -x direction sensor, the swing angle of the swing direction corresponding to the -x direction sensor is adjusted; that is, when the swing amplitude of the reflector is adjusted according to the reflected light intensity signal obtained by the -y direction sensor, the swing angle of the swing direction corresponding to the -y direction sensor is adjusted.

[0053] When the swing angles of the reflector in various directions are adjusted according to the signals of the above-mentioned +x direction sensor, +y direction sensor, -x direction sensor, and -y direction sensor, the reflector is adjusted according to the reflector swing angle adjustment requirements required in various directions corresponding to each sensor. The final result of the change in the swing angle of the reflector is the vector superposition of the changes in the swing angles in the +x, +y, -x, and -y directions.

[0054] Preferably, the swing motor can also be controlled accordingly through the conversion relationship between the waveform data of each photoelectric sensor and the swing angle of the reflector in the corresponding direction.

[0055] For example, according to the conversion relationship between the width or falling speed of the falling edge of the reflected light intensity waveform of each photoelectric sensor and the swing angle of the galvanometer (reflector) in each direction, the swing motor is controlled accordingly to correct the swing amplitude of the reflector in the corresponding direction to achieve uniformity of the light spot.

[0056] If it is detected that the intensity of a photoelectric sensor signal is too low or the falling edge is too wide, the swing angle of the swing motor in the corresponding direction can be reduced appropriately to increase the laser power density and welding speed.

[0057] Preferably, when it is detected that the width of the falling edge (first falling edge or second falling edge) of each (certain) photoelectric sensor signal is greater than a third predetermined width, the laser output power of the laser output portion 6 can be increased and / or the swing angle of the swing motor in each (certain) corresponding direction can be reduced within the second range. Preferably, the third predetermined width can be set to 700 microseconds, preferably the third predetermined width can be set to 500 microseconds, or, preferably, the third predetermined width can be set to 300 microseconds.

[0058] Based on the above, the inventors realized that if the width of each falling edge can be maintained consistent in practice, then the laser power density at the weld point in a continuous welding mode or a quasi-continuous welding mode can be very accurately maintained. This is more direct and accurate than the conventional method of controlling the laser output light power in the prior art. In the prior art, only the laser output power is controlled. However, the laser output power does not directly correspond to the laser power density at the weld point. The process of the laser output power affecting the power density at the weld point needs to consider factors such as power loss during the laser output process, power instability, unstable operator handholding, and swing angle deviation. Therefore, if only the laser output power is controlled to be stable, it is not possible to accurately control the stability of the laser power density at the weld point. The laser power density at the weld point is the most directly related to the welding effect and welding consistency. If the laser power density at the weld point can be directly controlled to be very stable, the consistency of the welding process can be greatly improved.

[0059] Therefore, preferably, in certain welding procedures, a required welding point power density can be preset, and accordingly, the falling edge (first falling edge or second falling edge) width can be set manually or by a processor to be within a first set range according to the required welding point energy density. The first set range is that the falling edge (first falling edge or second falling edge) width is greater than the lower limit of the first set range, and the first set range is that the falling edge (first falling edge or second falling edge) width is less than the upper limit of the first set range. Preferably, the upper limit of the first set range and / or the lower limit of the first set range are between 30 microseconds and 700 microseconds, preferably, the upper limit of the first set range and / or the lower limit of the first set range are between 50 microseconds and 500 microseconds. Preferably, the difference between the upper limit of the first set range and the lower limit of the first set range is less than 100 microseconds; preferably, the difference between the upper limit of the first set range and the lower limit of the first set range is less than 50 microseconds; preferably, the difference between the upper limit of the first set range and the lower limit of the first set range is less than 20 microseconds.

[0060] Preferably, when in continuous welding mode, when the energy density of the welding point needs to be stabilized, when the width of the first falling edge or the second falling edge of the sensor in the i-th cycle obtained by the processor is within the first set range, the processor does not issue an instruction to change the laser power or change the swing angle; when the width of the first falling edge or the second falling edge obtained by the processor is greater than the upper limit of the first set range, the processor increases the laser output power of the laser output part 6 and / or decreases the swing angle of the swing motor in the corresponding direction until the width of the first falling edge or the second falling edge in the i+m-th cycle is within the first set range; when the width of the first falling edge or the second falling edge obtained by the processor is less than the lower limit of the first set range, the laser output power of the laser output part 6 is reduced and / or the swing angle of the swing motor in the corresponding direction is increased until the width of the first falling edge or the second falling edge in the i+n-th cycle is within the first set range.

[0061] When the laser instruction is normal, that is, the control signal output by the control system 5 to the laser driving system 7 is the normal welding laser mode, that is, the output power of the laser driving system 7 driving the laser to work is greater than the first predetermined power value and less than the second predetermined power value (the first predetermined power value is less than the second predetermined power value. When the output power of the laser is between the first predetermined power value and the second predetermined power value, the laser output by the laser output part can be used for normal welding of the workpiece), but the reflection signal detected by each photoelectric sensor is lower than the first preset reflection intensity threshold, it can be judged that the laser welds through the material, the laser is transparent or is in an abnormal welding state. The controller controls the laser welding equipment to shut down and automatically alarm to protect the safety of the operator and the equipment.

[0062] Different metal materials have different reflectivity. Therefore, the reflection intensity threshold can be set by the user according to the metal material being welded and the actual welding conditions.

[0063] This intensity threshold is the light-off threshold. If the signal strength of any photoelectric sensor is lower than the threshold, the light should be turned off. If the signal strength is within the threshold range, the swing amplitude is adjusted.

[0064] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. An adjustable handheld laser welding head, including a collimation system, a reflection system, a focusing system, a detection system, a control system, a laser output part and a laser drive system; The laser output part includes a laser part for generating welding laser and an output optical fiber for outputting welding laser; The collimation system includes a collimating lens for shaping the divergent light beam output from the optical fiber into a collimated laser; The reflection system includes a reflection lens and a swing motor. The reflection lens can swing under the control of the swing motor to achieve the trajectory swing of the collimated light beam. The focusing system includes a focusing lens for focusing the collimated laser beam; The detection system includes one or more photoelectric sensors for detecting reflected light; The control system includes a data processor and a controller. The data processor processes the electrical signal output by the photoelectric sensor. The controller controls the swing motor of the reflection system and / or the laser output drive system according to the signal output by the data processor. The laser driving system is used to drive the welding laser to be output from the laser output part. It can drive the laser output part to output the welding laser by receiving the signal output by the control system. In the reflected light intensity waveform of the photoelectric sensor, the reflected light intensity signal P(t) shows an upward trend from the time when the light is turned on to t1, and shows a downward trend between t1 and t2. The reflected light intensity signal curve of P(t) from t1 to t2 is the first falling edge. After reaching t2, P(t) remains basically unchanged until t3. Between t3 and t4, the reflected laser light intensity P(t) shows a downward trend. The reflected light intensity signal curve of P(t) from t3 to t4 is the second falling edge. When the first falling edge width or the second falling edge width is less than the second preset width value, the laser power density is reduced by the control system. When the first falling edge width or the second falling edge width is greater than the third preset width, the laser power density is increased by the control system.

2. According to the adjustable handheld laser welding head according to claim 1, the detection system obtains the reflected light intensity data after the laser welding starts, the control system analyzes the waveform of the reflected light intensity data, and the control system controls the swing motor and / or the laser output drive system of the reflection system according to the waveform of the reflected light signal intensity detected by the photoelectric sensor that changes with time.

3. The handheld laser welding head according to claim 1 is configured to reduce the laser power density by increasing the swing angle of the swing motor in each direction as needed, or to increase the laser power density by reducing the swing angle of the swing motor in each direction as needed.

4. According to the handheld laser welding head of claim 2, when the first falling edge width or the second falling edge width of the reflected light intensity signal waveform of the photoelectric sensor is lower than the second preset width value, the power density of the welding laser is reduced, the laser output power of the laser output part is reduced and / or the swing angle of the swing motor in each direction is increased within the first range.

5. According to the handheld laser welding head of claim 2, when the first falling edge width or the second falling edge width of the reflected light intensity signal waveform of the photoelectric sensor is less than the first preset width, the controller immediately turns off the laser; or, when the output power of the laser driving system driving the laser to work is greater than the first predetermined power value and less than the second predetermined power value, the first predetermined power value is less than the second predetermined power value, and when the output power of the laser working is between the first predetermined power value and the second predetermined power value, when the reflected signal detected by each photoelectric sensor is lower than the first preset reflection intensity threshold, the controller controls the laser welding equipment to turn off.

6. According to the handheld laser welding head of claim 3, when in continuous welding mode, when the energy density of the welding point needs to be stabilized, when the width of the first falling edge or the second falling edge of the sensor in the i-th cycle obtained by the processor is within the first set range, the processor does not issue an instruction to change the laser power or change the swing angle; when the width of the first falling edge or the second falling edge obtained by the processor is greater than the upper limit of the first set range, the processor increases the laser output power of the laser output part and or reduces the swing angle of the swing motor in the corresponding direction until the width of the first falling edge or the second falling edge in the i+m-th cycle is within the first set range; when the width of the first falling edge or the second falling edge obtained by the processor is less than the lower limit of the first set range, the laser output power of the laser output part is reduced and or the swing angle of the swing motor in the corresponding direction is increased until the width of the first falling edge or the second falling edge in the i+n-th cycle is within the first set range.

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