A laser-flame composite cutting method and system based on gas distribution

Abstract

This invention discloses a laser-flame composite cutting method based on gas distribution, belonging to the field of laser processing technology. The method includes: dividing a shared oxygen source into first and second oxygen branches; the first branch serves as a first channel for delivering cutting oxygen to the center of a composite nozzle, which is coaxially injected into the cutting area with the laser beam; the second branch serves as a premixing of combustion-supporting oxygen and fuel gas, delivered to a second channel surrounding the first channel, and after primary beam splitting, turbulent mixing, and secondary beam splitting, it is ejected around the laser beam and ignited by the laser beam to form a flame. This invention also discloses a corresponding cutting system. Through primary beam splitting, turbulent mixing, and secondary beam splitting, combined with appropriate gas pressure distribution, this invention achieves uniform distribution and thorough mixing of the combustible mixture; by employing a closed-loop adjustment strategy of first adjusting the combustion-supporting oxygen and then adjusting the fuel gas, combined with flame spectral feedback, the reducing flame can be quickly restored to a neutral flame. This invention has the advantages of high cutting quality and fast adjustment response.

Description

Technical Field

[0001] This invention belongs to the field of laser processing technology, specifically relating to a laser-flame composite cutting method and system based on gas distribution. Background Technology

[0002] Laser-flame hybrid cutting technology is widely used in metal processing, especially for the efficient cutting of thick metal plates. This technology, through the synergistic effect of flame preheating and laser cutting, improves cutting efficiency and quality while reducing laser power requirements. In laser-flame hybrid cutting, three gases typically work together: fuel gas and combustion oxygen are mixed to form a preheating flame, heating the workpiece to a certain temperature; cutting oxygen is coaxially injected with the laser beam to assist the laser in completing the cutting. Precisely controlling the distribution and ratio of these three gases, and adjusting the gas path parameters in real time according to the flame state, are key factors affecting the cutting effect.

[0003] In existing composite nozzles, the fuel gas and combustion-supporting oxygen are premixed and then delivered to an annular channel surrounding the laser beam to form a flame. This annular channel has a simple structure, allowing the combustible mixture to enter and exit directly, which presents the following problems: First, the airflow distribution at the inlet is uneven, easily causing flow deviation; second, the mixing path is short, resulting in insufficient mixing of the fuel gas and oxygen, leading to poor flame stability; third, the airflow distribution at the outlet is uneven, causing the flame to be unevenly distributed around the laser beam, resulting in uneven heating of the workpiece and affecting cutting quality.

[0004] Furthermore, in existing technologies, the combustion gas, combustion-supporting oxygen, and cutting oxygen are each controlled in an open-loop manner by their respective proportional valves according to preset fixed pressure values. Operators pre-set the pressure values ​​of the three gases before cutting based on process parameters such as workpiece thickness and material, and no adjustments are made during the cutting process. For judging the flame state, existing technologies primarily rely on operators visually observing the flame color and shape, judging the current flame state based on experience, and manually adjusting the gas path parameters accordingly. This method of judgment suffers from problems such as high subjectivity, delayed response, and lack of quantification.

[0005] In summary, existing technologies suffer from problems such as uneven airflow distribution, insufficient mixing, and uneven circumferential flame distribution in terms of nozzle structure. Furthermore, they lack a closed-loop adjustment mechanism based on flame state feedback in terms of gas control. There is an urgent need to provide a laser flame composite cutting method and system that can solve the above-mentioned technical problems. Summary of the Invention

[0006] In response to one or more of the above-mentioned defects or improvement needs of the existing technology, the present invention provides a laser flame composite cutting method and system based on gas distribution, which aims to solve the technical problems of uneven airflow distribution, insufficient mixing and uneven circumferential flame distribution in existing composite nozzles, and effectively improve the cutting quality of laser flame composite cutting.

[0007] To address the aforementioned technical problems, according to one aspect of the present invention, a laser-flame composite cutting method based on gas distribution is provided, comprising the following steps: A common oxygen source is provided, the common oxygen source including a first oxygen branch and a second oxygen branch; The first oxygen branch is used as cutting oxygen and is delivered to the first channel in the middle of the composite nozzle, where it is coaxially sprayed into the cutting area with the laser beam. The second oxygen branch serves as the combustion-supporting oxygen, which is premixed with the gas supplied by the gas pipeline in the mixing chamber to form a combustible mixture. The combustible mixture is transported through the mixing chamber outlet to a second channel surrounding the first channel. The second channel includes an inlet section, a mixing section, and an outlet section. The combustible mixture is split once in the inlet section, so that it is evenly distributed around the inlet of the second channel. Then, the combustible mixture undergoes turbulent mixing in the mixing section, so that the fuel gas and the oxygen for combustion are fully mixed. Finally, the combustible mixture is split a second time in the outlet section, so that it is evenly distributed around the outlet of the second channel again, and then coaxially ejected around the laser beam, and ignited by the laser beam to form a flame. The laser beam, flame, and cutting oxygen are applied together to the workpiece cutting area to achieve laser-flame composite cutting.

[0008] As a further improvement of the present invention, in laser-flame composite cutting, the ratio of combustion gas pressure, combustion oxygen pressure, and cutting oxygen pressure is 1:(8~12):(3~5); the ratio of laser power to cutting oxygen pressure is (0.5~3):1, where the unit of laser power is kW and the unit of cutting oxygen pressure is bar; and / or, During laser-flame composite cutting, the gas pressure is 0.4~0.6 bar, the combustion oxygen pressure is 4~6 bar, the cutting oxygen pressure is 1.5~2.5 bar, and the laser power is 1~6 kW.

[0009] As a further improvement of the present invention, after the combustible mixture is ignited by the laser beam to form a flame, the laser flame composite cutting method further includes: identifying the type of the flame and performing feedback adjustment according to the type of the flame, specifically including the following steps: The spectral signal of the flame is acquired to determine the type of flame based on the spectral signal; When the flame type is determined to be a reduction flame, the current gas pressure is kept constant, and the pressure of the combustion-supporting oxygen is increased step by step with a preset step size. After each increase, the pressure is maintained for a preset stable time, and the flame type is re-determined. If the flame is switched to a neutral flame or an oxidizing flame during this process, the current proportioning parameters are maintained and the adjustment process ends. If the flame is still a reduction flame after the oxygen pressure for combustion increases to the preset safety upper limit, the increase of oxygen for combustion is stopped, and the pressure of the gas is gradually decreased in preset steps. After each decrease, the pressure is maintained for a preset stable time, and the type of flame is re-determined. If the flame switches to a neutral flame or an oxidizing flame during the process of decreasing the gas pressure, the current ratio parameters are maintained and the adjustment process ends. If the flame remains a reduction flame after the gas pressure decreases to a preset lower limit, an abnormal protection procedure will be executed.

[0010] As a further improvement of the present invention, the increment of the combustion oxygen pressure is 0.1~0.2 bar, and the stabilization time after each increment is 0.5~1 second; The gas pressure is decreased in increments of 0.02 to 0.05 bar, and the settling time after each decrease is 0.5 to 1 second.

[0011] As a further improvement of the present invention, while executing the step-by-step closed-loop adjustment process, the laser-flame composite cutting method further includes synchronously adjusting the laser power according to the degree of deviation of the flame type, specifically including: When the flame type is a reduction flame, the laser power is increased step by step with a preset step size, and after each increase, a preset stable time is maintained, and the flame type is re-determined; When the laser power increases to the preset safety limit, the increase in laser power will stop; When the flame type is switched to a neutral flame or an oxidizing flame, the laser power is restored to the initial setting value.

[0012] As a further improvement of the present invention, the preset step size for successively increasing the laser power is 0.5~1 kW, and the preset stabilization time is 0.5~1 second.

[0013] As a further improvement of the present invention, a method for acquiring the current spectral signal of the flame and determining the current type of the flame based on the spectral signal includes: Extract the light intensity values ​​of the blue and yellow light bands of the flame, and calculate the light intensity ratio R of the blue and yellow light bands; when R is greater than the first threshold, it is determined to be a neutral flame; when R is less than the second threshold, it is determined to be a reducing flame; when R is between the first and second thresholds, it is determined to be an oxidizing flame. Wherein, the first threshold is greater than the second threshold.

[0014] According to another aspect of the present invention, a gas-distribution-based laser-flame composite cutting system is provided for the aforementioned gas-distribution-based laser-flame composite cutting method, comprising: An oxygen supply device, wherein the oxygen supply device has a first oxygen output terminal and a second oxygen output terminal; Cut the oxygen pipeline, connect the first oxygen output end to the first channel of the compound nozzle, and install a cutting oxygen proportioning valve on it. The combustion oxygen pipeline connects the second oxygen output end to the mixing chamber and is equipped with a combustion oxygen proportioning valve. A gas pipeline connects the gas source to the mixing chamber and is equipped with a gas proportional valve. The mixing chamber is used to receive and premix combustion-supporting oxygen and fuel gas to form a combustible mixture. Composite nozzle, including: The first channel, located in the middle, is used to allow the laser beam to pass through and receive cutting oxygen, so that the cutting oxygen is sprayed coaxially with the laser beam into the cutting area; The second channel, located outside the first channel, is used to transport the combustible mixture. The second channel is equipped with a primary beam splitting structure, a turbulence cavity, and a secondary beam splitting structure. A laser generator is used to generate a laser beam, which is transmitted through an optical path and then emitted from the first channel of the composite nozzle. The control unit is electrically connected to the gas proportional valve, the combustion oxygen proportional valve, the cutting oxygen proportional valve, and the laser generator, respectively.

[0015] As a further improvement of the present invention, a flame spectrum sensor is also provided on the composite nozzle. The flame spectrum sensor is electrically connected to the control unit. The control unit determines the type of flame based on the spectral signal collected by the flame spectrum sensor and outputs control commands to each proportional valve accordingly.

[0016] As a further improvement of the present invention, the primary beam splitting structure is a plurality of circumferentially uniformly distributed primary beam splitting holes disposed in the entrance section of the second channel; The turbulence cavity is an annular cavity disposed in the mixing section of the second channel, and its inner diameter is larger than the inner diameter of the inlet section and the outlet section; The secondary beam splitting structure consists of multiple circumferentially evenly distributed axial channels located at the outlet section of the second channel. The inlet section, the mixing section, and the outlet section are connected in sequence, so that the combustible mixture passes through a first split, turbulent mixing, and a second split before being ejected coaxially around the first channel.

[0017] In summary, the technical solutions conceived by this invention have the following beneficial effects compared with the prior art: (1) The cutting gas of the present invention undergoes a progressive process of primary beam splitting, mixing, and secondary beam splitting. The combustible mixture undergoes three stages in sequence: inlet homogenization, turbulent mixing, and outlet homogenization, forming a complete airflow organization from uniform inflow to full mixing and then uniform ejection. Compared with the simple annular channel direct ejection method in the prior art, the technical solution of the present invention has significant improvements in both the uniformity of airflow distribution and the fullness of mixing, thereby achieving a more stable flame shape and a more uniform circumferential heat distribution, effectively improving the cutting quality of laser flame composite cutting.

[0018] (2) In this invention, the pressure ratio of fuel gas, combustion-supporting oxygen and cutting oxygen is limited to 1:(8~12):(3~5). The excessive supply of combustion-supporting oxygen ensures complete combustion of the fuel gas. The cutting oxygen is distributed according to a reasonable ratio of the total oxygen flow. The laser power and the cutting oxygen pressure are matched and coordinated. The coordination of the three achieves the unity of complete combustion, reasonable oxygen distribution and laser energy matching, resulting in a smooth cutting surface without slag.

[0019] (3) This invention adopts a step-by-step closed-loop regulation strategy of first adjusting the combustion-supporting oxygen and then adjusting the fuel gas. When a reducing flame is identified, the combustion-supporting oxygen is increased in larger steps to quickly approach the target ratio. Only when the combustion-supporting oxygen is adjusted to the upper limit and becomes ineffective, the fuel gas is decreased in smaller steps. This strategy, while ensuring combustion continuity and safety, quickly switches the flame from a reducing state to a neutral or oxidizing state. This not only shortens the adjustment time and reduces the energy consumption of the transition state, but also extends the equipment life by suppressing carbon deposits and reducing frequent valve operations. At the same time, the dual protection mechanism of the upper limit of oxygen and the lower limit of fuel gas enhances the adaptability to multiple operating conditions and the reliability of the system.

[0020] (4) This invention uses the blue / yellow light intensity ratio as a quantitative criterion for flame type, replacing traditional manual visual observation. Compared with manual judgment, the spectroscopic method has the advantages of fast response speed, strong objectivity and high repeatability, providing a reliable and real-time feedback signal for closed-loop regulation, avoiding judgment errors and regulation lag caused by human factors.

[0021] (5) This invention uses a shared oxygen source, with both cutting oxygen and combustion oxygen coming from the same source, avoiding the energy loss of dual-source simultaneous supply in independent gas source schemes. At the same time, the shared oxygen source and pressure ratio design are highly compatible, avoiding oxygen waste and reducing operating costs. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the laser-flame composite cutting method based on gas distribution according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the connection of the gas distribution-based laser-flame composite cutting system according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the structure of a gas-distribution-based laser-flame composite cutting system according to an embodiment of the present invention; Figure 4 This is a schematic diagram of the three-dimensional structure of the composite nozzle (ceramic section + connecting section) according to an embodiment of the present invention. Figure 5 This is a schematic diagram of the three-dimensional structure of the inner cylinder of the nozzle section in the composite nozzle of this invention.

[0023] In all the accompanying drawings, the same reference numerals denote the same technical features, specifically: 1. Cut oxygen pipeline; 2. Combustion-supporting oxygen pipeline; 3. Gas pipeline; 4. Mixing chamber; 5. Compound nozzle; 51. Ceramic section; 52. Connecting section; 53. Nozzle section; 54. First channel; 55. Second channel; 531. Outer cylinder; 532. Inner cylinder; 551. Primary beam splitting hole; 552. Annular cavity; 553. Axial channel. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0025] Please see Figure 1 This invention provides a laser-flame composite cutting method based on gas distribution, comprising the following steps: A common oxygen source is provided, which includes a first oxygen branch and a second oxygen branch. The first oxygen branch is used as cutting oxygen, which is delivered to the first channel in the middle of the composite nozzle during cutting and sprayed coaxially with the laser beam into the cutting area; the second oxygen branch is used as combustion oxygen, which is premixed with the gas delivered by the gas pipeline in the mixing chamber to form a combustible mixture. The combustible mixture is transported from the outlet of the mixing chamber to the second channel outside the first channel. After passing through the inlet, mixing, and outlet sections of the second channel, it undergoes a first beam splitting, turbulent mixing, and a second beam splitting in sequence. It is then coaxially ejected in a manner that surrounds the laser beam and is ignited by the laser beam to form a flame. Laser-flame composite cutting is achieved by applying a laser beam, flame, and cutting oxygen to the workpiece cutting zone.

[0026] In this invention, the cutting gas undergoes a first beam split, turbulent mixing, and a second beam split in the second channel. The first beam split ensures a uniform circumferential distribution of the combustible mixture at the inlet, preventing flow deviation. The mixing section promotes thorough mixing of the combustible gas and oxygen through turbulence, improving flame stability. The second beam split further distributes the mixture at the outlet, ensuring a uniform flame distribution around the laser beam and improving the consistency of cutting quality. The synergistic effect of the first beam split, mixing, and second beam split creates an airflow organization that progresses from uniform inflow to thorough mixing and then to uniform ejection, significantly improving flame stability and the uniformity of the cutting cross-section.

[0027] In a preferred embodiment, during laser-flame composite cutting, the ratio of gas pressure, combustion oxygen pressure, and cutting oxygen pressure is 1:(8~12):(3~5). In this ratio, the combustion oxygen is supplied in excess at 0.8~1.2 times the theoretical air-fuel ratio (approximately 1:10) to ensure complete combustion and avoid reducing flames; the cutting oxygen is supplied at 3~5 times the gas quantity, naturally forming an oxygen distribution pattern of approximately 70% for combustion and 30% for cutting under shared oxygen source conditions. This ratio works in conjunction with the three-stage second channel: the first beam splitting evenly distributes the oxygen-rich mixture circumferentially, the mixing section uses turbulence to ensure sufficient contact between trace amounts of gas and a large amount of oxygen, and the second beam splitting ensures uniform circumferential flame ejection, thereby simultaneously improving both combustion completeness and distribution uniformity.

[0028] In a preferred embodiment, during laser-flame composite cutting, the ratio of laser power to cutting oxygen pressure is (0.5~3):1, where the laser power is in kW and the cutting oxygen pressure is in bar.

[0029] In this invention, there is a direct synergistic relationship between laser power and cutting oxygen pressure. Therefore, the laser power and cutting oxygen pressure must be matched. If the cutting oxygen pressure is too low, the molten slag cannot be effectively blown away; if the cutting oxygen pressure is too high, the molten pool will be over-cooled. Optimal cutting quality can be obtained when the ratio of laser power to cutting oxygen pressure is in the range of 0.5~3 kW / bar. Simultaneously, the laser power and flame thermal power complement each other, avoiding the high cost caused by solely relying on high-power lasers and overcoming the problem of insufficient energy density when solely relying on flame cutting.

[0030] In a preferred embodiment, the above-mentioned laser-flame composite cutting method further includes a flame type identification and feedback adjustment step: Collect the spectral signal of the flame to determine the type of flame based on the spectral signal; When the flame type is determined to be a reduction flame, the current gas pressure is kept constant, and the pressure of the combustion-supporting oxygen is increased step by step with a preset step size. After each increase, the pressure is maintained for a preset stable time, and the flame type is re-determined. If the flame is switched to a neutral flame or an oxidizing flame during this process, maintain the current mixing parameters and end the adjustment process; If the flame is still a reduction flame after the oxygen pressure for combustion increases to the preset safety upper limit, the increase of oxygen for combustion is stopped, and the pressure of the gas is gradually decreased in preset steps. After each decrease, the pressure is maintained for a preset stable time, and the type of flame is re-determined. If the flame switches to a neutral flame or an oxidizing flame during the process of decreasing the gas pressure, then maintain the current ratio parameters and end the adjustment process. If the flame remains a reduction flame after the gas pressure decreases to a preset lower limit, an abnormal protection procedure will be executed.

[0031] It should be noted that when the pressure of the combustion-supporting oxygen is increased, the pressure of the cutting oxygen changes synchronously in the opposite direction due to the shared oxygen source (i.e., the cutting oxygen pressure decreases successively), forming a reverse coordinated regulation between the combustion-supporting oxygen and the cutting oxygen. This mechanism utilizes the split coupling characteristics under a shared oxygen source, eliminating the need for a separate actuator and regulation logic for the cutting oxygen, thus achieving adaptive reverse regulation of the cutting oxygen, simplifying the complexity of the control system and reducing hardware costs.

[0032] More preferably, the specific adjustment steps are as follows: S1 Flame Status Acquisition.

[0033] Collect the spectral signal of the flame to determine the current flame type; If the flame is determined to be neutral or oxidizing, maintain the current ratio of fuel gas to oxygen for combustion. If the flame is determined to be a reducing flame, then the following closed-loop regulation process will be initiated; S2: Closed-loop regulation process.

[0034] S21 keeps the current gas pressure constant, increases the oxygen pressure in increments of 0.1~0.2 bar, maintains a stable time of 0.5~1 seconds after each increase, and then re-determines the flame type; S22: If the flame switches to a neutral flame or an oxidizing flame during this process, maintain the current proportioning parameters and exit the adjustment process; S23 If the flame is still a reduction flame after the combustion oxygen pressure is increased to the preset safety upper limit, the increase of combustion oxygen is stopped, and the gas pressure is decreased in increments of 0.02~0.05 bar. After each decrease, the pressure is stabilized for 0.5~1 seconds, and the flame type is re-evaluated. S24: If the flame switches to a neutral flame or an oxidizing flame during the process of decreasing the gas pressure, then lock the current ratio parameters and exit the adjustment process; S3: Anomaly protection.

[0035] If the flame remains a reduction flame after the gas pressure decreases to the preset lower limit, an alarm signal will be issued and the flameout protection procedure will be executed.

[0036] This invention employs a dynamic adjustment sequence, first adjusting the combustion oxygen and then the fuel gas. Initially, the combustion oxygen is adjusted in large increments (0.1~0.2 bar) to quickly approach the target ratio, ensuring continuous flame combustion while shortening the adjustment time and reducing transitional energy consumption. When increasing the combustion oxygen to the safe upper limit becomes ineffective, the fuel gas is reduced in smaller increments (0.02~0.05 bar), avoiding the risk of flameout and actuator wear caused by frequent fuel gas fluctuations. Simultaneously, forced combustion towards complete oxidation effectively suppresses carbon buildup, protecting cutting quality and cut consistency. A 0.5~1 second stabilization waiting time prevents frequent erroneous adjustments, and combined with fuel gas lower limit protection and flameout alarm mechanisms, the system possesses multi-condition adaptive capabilities and high safety and reliability.

[0037] In this invention, the voltage-pressure mapping relationship of the gas is preferably set to 0~10V corresponding to 0~3bar, and the voltage-pressure mapping relationship of the oxygen for combustion is set to 0~10V corresponding to 0~9bar. This mapping range defines the safe operating boundary of each gas circuit proportional valve. The upper limit of safety is set according to the maximum output capacity of the proportional valve. Exceeding this value may cause valve damage or sealing failure. The lower limit of safety is set according to the minimum gas pressure required to maintain the flame. When this value is reached, the flame will be extinguished.

[0038] Furthermore, the preferred operating range for laser-flame composite cutting is: gas pressure 0.4~0.6 bar, combustion oxygen pressure 4~6 bar, cutting oxygen pressure 1.5~2.5 bar, and laser power 1~6 kW. This preferred range falls within the aforementioned safety boundaries and is the experimentally verified optimal interval within those safety boundaries.

[0039] During the closed-loop regulation process, fine adjustments are made within the preferred operating range; when the adjustment exceeds the preferred range but remains within the safety boundary, the system continues to attempt recovery; when the combustion oxygen pressure increases to the upper limit but the reducing flame cannot be eliminated, the system switches to reducing the gas pressure; when the gas pressure drops to the lower limit but recovery is still not possible, the system immediately executes flameout protection to ensure the safety of the regulation process.

[0040] More preferably, the method for determining the current flame type is as follows: extract the light intensity values ​​of the blue light band and the yellow light band, and calculate the light intensity ratio R of the blue light band and the yellow light band; when R is greater than a first threshold, it is determined to be a neutral flame; when R is less than a second threshold, it is determined to be a reducing flame; when R is between the first threshold and the second threshold, it is determined to be an oxidizing flame; wherein, the first threshold is greater than the second threshold.

[0041] The first threshold and the second threshold are pre-calibrated according to the flame spectral characteristics. More preferably, the first threshold, the second threshold, and the third threshold are calibrated by the following method: Under standard combustion conditions, establish three combustion states of neutral flame, oxidizing flame, and reducing flame; collect the flame spectral signals in each state, extract the light intensity values in the blue light band and the yellow light band, and calculate the blue light / yellow light ratio R; take the lowest value of the R value in the neutral flame state as the first threshold, take the highest value of the R value in the reducing flame state as the second threshold, and the R value in the oxidizing flame state is between the second threshold and the first threshold. In a preferred embodiment of the present invention, determined by the above calibration method, the first threshold is 2.0 and the second threshold is 0.5. That is: when R≥2.0, it is determined as a neutral flame; when R≤0.5, it is determined as a reducing flame; when 0.5<R<2.0, it is determined as an oxidizing flame.

[0042] The present invention determines the flame type based on the principle of flame spectral quantitative analysis. The blue light band (400~480nm) corresponds to the chemiluminescence of CH radicals, representing complete combustion, visually manifested as a neutral flame (clear inner cone, slightly blue outer flame) or an oxidizing flame (short white inner cone, blue outer flame); the yellow light band (570~600nm) corresponds to the thermal radiation of unburned carbon particles, representing incomplete combustion, visually manifested as a reducing flame (large inner cone, yellow outer flame). The more complete the combustion, the stronger the blue light, the weaker the yellow light, and the higher the light intensity ratio of blue light to yellow light; conversely, the lower the ratio. Based on this, the present invention collects the light intensities in the blue light and yellow light bands through a spectral sensor, and uses the blue light / yellow light ratio as a quantitative criterion to replace the manual naked-eye observation, realizing the objective and rapid quantitative identification of the flame type.

[0043] More preferably, a regulation hysteresis interval is also set in the feedback regulation step, that is, when the flame fluctuates at the boundary between the reducing flame and the neutral flame, the regulation action is delayed by 2 to 5 seconds to execute, avoiding frequent regulation due to instantaneous fluctuations.

[0044] More preferably, while executing the step-by-step closed-loop regulation process, the laser power is synchronously adjusted according to the deviation degree of the flame type: When the flame type is a reducing flame, the laser power is increased successively in a preset step size, and after each increase, it is maintained for a preset stable time, and the flame type is rejudged; When the laser power increases to the preset safety upper limit value, the increase of the laser power is stopped; When the flame type switches to a neutral flame or an oxidizing flame, the laser power is restored to the initial set value.

[0045] Preferably, the preset step size is 0.5~1 kW, the preset stable time is 0.5~1 second, and the safety upper limit can be adjusted according to the working characteristics of the laser generator and the requirements of the cutting process, for example, set as 1.5 times the initial laser power and not exceeding 90% of the rated power of the laser generator.

[0046] This invention further incorporates a laser power synchronization compensation mechanism. When the flame type is identified as a reducing flame, the control unit simultaneously sends a gas regulation command to the gas path execution module and a power compensation command to the laser generator, increasing the laser power in preset steps. Since the response speed of the laser power is much faster than that of the gas pressure regulation speed (milliseconds for laser, seconds for gas), this compensation mechanism can temporarily increase the cutting energy during the gas regulation transition period, compensating for the decrease in flame preheating energy caused by incomplete combustion and preventing a precipitous drop in cutting energy. When the flame returns to a neutral or oxidizing flame, the laser power synchronously returns to the initial set value. This mechanism effectively improves the continuity and stability of the cutting process, and is particularly suitable for conditions with abrupt changes in thickness or uneven material composition.

[0047] Furthermore, such as Figures 2 to 5 As shown, this embodiment of the invention also provides a laser flame composite cutting system based on gas distribution, including an oxygen supply device, a cutting oxygen pipeline 1, a combustion oxygen pipeline 2, a gas pipeline 3, a laser generator, and a control unit.

[0048] The oxygen supply device has a first oxygen output end and a second oxygen output end; the cutting oxygen pipeline 1 connects the first oxygen output end to the first channel of the composite nozzle, and a cutting oxygen proportional valve is installed on it. The combustion oxygen pipeline 2 connects the second oxygen output end to the mixing chamber, and a combustion oxygen proportional valve is installed on it. The gas pipeline 3 connects the gas source to the mixing chamber, and a gas proportional valve is installed on it. The mixing chamber 4 is used to receive and premix the combustion oxygen and gas to form a combustible mixture. The composite nozzle 5 includes a first channel 54 located in the middle and a second channel 55 located around the first channel 54. The first channel 54 is used to allow the laser beam to pass through and receive the cutting oxygen, so that the cutting oxygen and the laser beam are coaxially injected into the cutting area; the second channel 55 is used to transmit the combustible mixture, and a primary beam splitting structure, a turbulence chamber, and a secondary beam splitting structure are provided in the second channel 55, so that the combustible mixture passes through the primary beam splitting, mixing, and secondary beam splitting in sequence and is coaxially ejected around the laser beam.

[0049] The laser generator produces a laser beam, which is transmitted through an optical path and then emitted from the first channel of the composite nozzle. The control unit is electrically connected to the gas proportional valve, the combustion oxygen proportional valve, the cutting oxygen proportional valve, and the laser generator.

[0050] In a preferred embodiment, the laser flame composite cutting system further includes a flame spectrum sensor, preferably disposed on the outer wall of the composite nozzle 5, with its acquisition end facing the nozzle outlet direction, for acquiring flame spectrum signals; the flame spectrum sensor is electrically connected to the control unit, and the control unit determines the current flame type based on the signal acquired by the flame spectrum sensor, and outputs control commands to each proportional valve accordingly.

[0051] In a preferred embodiment, the primary beam splitting structure consists of multiple circumferentially evenly distributed primary beam splitting holes 551 disposed in the inlet section of the second channel 55; the turbulent flow cavity is an annular cavity 552 disposed in the mixing section of the second channel 55, the inner diameter of which is larger than the inner diameter of the inlet section and the outlet section; the secondary beam splitting structure consists of multiple circumferentially evenly distributed axial channels 553 disposed in the outlet section of the second channel 55; the inlet section, the mixing section and the outlet section are connected in sequence, so that the combustible mixture passes through the primary beam splitting, turbulent mixing and secondary beam splitting in sequence and is then ejected coaxially around the first channel.

[0052] like Figures 3 to 5 As shown, a preferred embodiment of the present invention provides a specific composite nozzle 5 structure. The composite nozzle 5 includes a ceramic segment 51, a connecting segment 52 and a nozzle segment 53 arranged in segments. The three segments are coaxially connected in sequence, and a first through channel 54 is provided in the middle of the three segments.

[0053] Multiple circumferentially evenly distributed and sequentially connected primary beam splitting holes 551 are provided around the first channel 54 in the ceramic section 51 and the connecting section 52, which together constitute a primary beam splitting structure. The nozzle section 53 includes an outer cylinder 531 and an inner cylinder 532 coaxially sleeved together. The inner cylinder 532 is part of the first channel 54. The inner diameter of the through hole on the side of the outer cylinder 531 facing the connecting section 52 is larger than the inner diameter of the through hole on the side of the inner cylinder away from the connecting section 52, forming an annular cavity 552 with the inner cylinder 532, which serves as a turbulent flow cavity. Multiple axial channels 553 are provided on the outer peripheral sidewall of the inner cylinder 532 away from the connecting section 52, forming a secondary bundle structure with the outer cylinder. The primary beam splitting structure, the turbulent flow cavity, and the secondary beam splitting structure are connected in sequence to form the second channel 55, so that the combustible mixture passes through the primary beam splitting, turbulent mixing, and secondary beam splitting in sequence and is then ejected coaxially around the first channel 54.

[0054] It should be noted that, Figures 2 to 5 The gas distribution, mixing chamber, and composite nozzle structures related to the inventive point of this invention are highlighted, and... Figure 3 The oxygen cutting line 1, combustion oxygen line 2, gas line 3, and mixing chamber 4 are for illustrative purposes only; their specific arrangement can be adjusted according to actual conditions. The shared oxygen source, laser generator, control unit, flame spectrum sensor, and electrical connections between the proportional valves and the control unit are not shown individually in the figure. Those skilled in the art will understand that the components not shown above and their connections can be configured with reference to conventional laser-flame composite cutting equipment, without affecting the full disclosure and understanding of the technical solution of this invention.

[0055] This invention incorporates a ceramic segment structure. When the laser-flame composite cutting device malfunctions and comes into contact with the substrate, the ceramic segment undergoes brittle fracture, preventing the impact force from being transmitted to the mounting structure and laser module above the composite nozzle, thus avoiding overall damage to the laser-flame composite cutting device. Furthermore, the composite nozzle is designed as a three-section structure consisting of a ceramic segment, a connecting segment, and a nozzle segment, allowing the ceramic segment to be replaced individually. This prevents overall nozzle damage after the laser-flame composite cutting device comes into hard contact with the substrate. In addition, the primary and secondary beam splitting structures ensure uniform airflow distribution, preventing localized airflow concentration from eroding and wearing the nozzle's inner wall. The turbulent design of the turbulent cavity promotes thorough mixing of the combustion gas and oxygen, reducing carbon buildup caused by incomplete combustion and extending the nozzle's service life.

[0056] To better illustrate the technical solution and effects of the present invention, the following embodiments and comparative examples are provided: Example 1 This embodiment provides a gas-distribution-based laser-flame composite cutting method for cutting carbon steel plates with a thickness of 30mm.

[0057] This embodiment uses a shared oxygen source, which is divided into a first oxygen branch (cutting oxygen) and a second oxygen branch (combustion-supporting oxygen) via a gas distribution unit. The pressure ratio of fuel gas, combustion-supporting oxygen, and cutting oxygen is set to 1:10:4, with specific parameter settings as follows: Gas supply: 0.5 bar, 0~10V corresponds to 0~3 bar (corresponding to a control voltage of approximately 1.67V); Combustion-supporting oxygen supply: 5.0 bar, 0~10V corresponds to 0~9 bar (corresponding to a control voltage of approximately 5.56V); Cutting oxygen supply: 2.0 bar; Laser power: 3kW.

[0058] The specific method is as follows: The gas and combustion-supporting oxygen are turned on and supplied at the aforementioned pressure. The combustible mixture is premixed in the mixing chamber and then enters the second channel 55 of the composite nozzle. In the second channel 55, the combustible mixture sequentially passes through primary beam splitting (primary beam splitting orifice 551), turbulent mixing (annular cavity 552), and secondary beam splitting (inner cylinder axial channel 553), before being coaxially ejected around the laser beam. The laser beam ignites the combustible mixture to form a preheating flame, preheating the workpiece to approximately 800°C. Then, the cutting oxygen is turned on and coaxially injected with the laser beam into the cutting area, working together to complete the cutting of the workpiece.

[0059] During the cutting process, the flame spectral sensor collects the spectral signal of the flame in real time. When the flame type is identified as a reduction flame, the system automatically executes a step-by-step closed-loop adjustment process: First, increase the oxygen pressure in increments of 0.1 bar, stabilizing for 0.5 seconds after each increase. If the combustion oxygen pressure remains a reducing flame after reaching 9 bar, decrease the gas pressure in increments of 0.02 bar, stabilizing for 0.5 seconds after each decrease. Once the flame returns to a neutral or oxidizing flame, lock the blending ratio. If the gas pressure remains a reducing flame after dropping to 0 bar, activate the flameout protection.

[0060] In this embodiment, the flame exhibits neutral flame characteristics: a clear inner cone, a slightly blue outer flame, complete combustion, and a uniform circumferential distribution of the flame.

[0061] Example 2 This embodiment provides a laser-flame composite cutting method based on gas distribution, which differs from Embodiment 1 in that: This embodiment is used to cut a carbon steel plate with a thickness of 20mm. The specific parameters are set as follows: fuel gas 0.5 bar, combustion oxygen 4.0 bar, cutting oxygen 1.5 bar, and laser power 2.5kW.

[0062] During the cutting process, the flame spectral sensor collects spectral signals in real time. When a reducing flame is detected, the system executes closed-loop regulation: first, the combustion oxygen pressure is increased in increments of 0.15 bar, stabilizing for 0.6 seconds after each increase; if the combustion oxygen pressure remains a reducing flame after increasing to 9 bar, the gas pressure is decreased in increments of 0.03 bar, stabilizing for 0.8 seconds after each decrease; the fuel mixture is locked after the flame returns to a neutral or oxidizing flame; if the gas pressure drops to 0 bar and the flame remains a reducing flame, flameout protection is activated.

[0063] In this embodiment, the flame exhibits characteristics of a neutral flame with a slight oxidizing tendency: the inner cone is slightly shorter, the outer flame is bluish, and combustion is complete, making it suitable for cutting thinner plates.

[0064] Example 3 This embodiment provides a laser-flame composite cutting method based on gas distribution, which differs from Embodiment 1 in that: This embodiment is used to cut a carbon steel plate with a thickness of 40mm. The specific parameters are set as follows: fuel gas 0.5 bar, combustion oxygen 6.0 bar, cutting oxygen 2.5 bar, and laser power 5kW.

[0065] During the cutting process, the flame spectral sensor collects spectral signals in real time. When a reducing flame is detected, the system executes closed-loop regulation: first, the combustion oxygen pressure is increased in increments of 0.2 bar, stabilizing for 1 second after each increase; if the combustion oxygen pressure remains a reducing flame after increasing to 9 bar, the gas pressure is decreased in increments of 0.05 bar, stabilizing for 1 second after each decrease; the fuel mixture is locked after the flame returns to a neutral or oxidizing flame; if the gas pressure drops to 0 bar and the flame remains a reducing flame, flameout protection is activated.

[0066] In this embodiment, the flame exhibits characteristics of a neutral flame with a slight oxidation: a short inner cone and a bright blue outer flame, resulting in very complete combustion, making it suitable for cutting thicker plates.

[0067] Comparative Examples 1 to 5 Among them, Comparative Examples 1 to 3 differ from Example 1 in the specific pressure ratio; Comparative Example 3 differs from Example 1 in that it uses a conventional nozzle structure; the difference lies in the initial pressure ratio being set to 1:6:4 (0.5 bar of fuel gas, 3 bar of combustion oxygen, and 2 bar of cutting oxygen), and open-loop control is used, with no feedback adjustment during the cutting process. The specific settings and results are shown in Table 1 below: Table 1 Comparative examples and experimental results

[0068] The results showed that in Comparative Examples 1 to 3, when the gas pressure was below 0.5 bar or the oxygen pressure was below 5 bar, the flame was reddish or slightly red, the flame shape was short, and the combustion was incomplete. The cutting quality was characterized by severe slag buildup in the cut and a rough cross-section. Only when the gas pressure reached 0.5 bar, the oxygen pressure reached 5 bar, and the cutting oxygen was 2 bar (i.e., the ratio was 1:10:4) did the flame appear slightly blue, the flame shape was moderate, the combustion was complete, the cut was free of slag, and the cross-section was smooth, thus verifying the effectiveness of the optimal ratio.

[0069] Comparative Example 4 shows that when using a traditional simple annular channel, although the proportions are correct and combustion is complete, the circumferential distribution of the flame is uneven, resulting in poor consistency of the cutting section. However, the present invention significantly improves the uniformity of flame distribution through the synergistic effect of primary beam splitting, turbulence and secondary beam splitting, making the cutting section uniform and consistent.

[0070] Comparative Example 5 shows that when the initial ratio deviates under open-loop control, the flame cannot be automatically restored, resulting in poor cutting quality. However, the present invention adopts a step-by-step closed-loop adjustment strategy of first adjusting the combustion-supporting oxygen and then adjusting the gas, which can quickly correct the ratio to the optimal range, restore the cutting quality to the level of no slag and smooth cross-section, and at the same time avoid the risk of flameout caused by frequent fluctuations in gas.

[0071] In summary, the pressure ratio, three-stage nozzle structure, and dynamic adjustment strategy of this invention work synergistically to achieve comprehensive technical effects such as full combustion, uniform distribution, rapid recovery, and excellent cutting quality.

[0072] It should be noted that the reddish flame observed in the above experimental results is essentially a manifestation of incomplete combustion, where a large number of unburned carbon particles are generated and their size increases, causing the peak thermal radiation to shift towards the red light band. This phenomenon, along with the yellowish flame, falls under the category of a reduced blue / yellow light ratio, with the reddish state corresponding to an even lower blue / yellow light ratio. Therefore, this invention can fully characterize the entire range of flame states, from complete combustion (blued) to severe incomplete combustion (reddish), using only the intensity ratio of the two characteristic bands, blue and yellow, without the need for a separate red light band.

[0073] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A laser-flame composite cutting method based on gas distribution, characterized in that, Includes the following steps: A common oxygen source is provided, the common oxygen source including a first oxygen branch and a second oxygen branch; The first oxygen branch is used as cutting oxygen and is delivered to the first channel in the middle of the composite nozzle, where it is coaxially sprayed into the cutting area with the laser beam. The second oxygen branch serves as the combustion-supporting oxygen, which is premixed with the gas supplied by the gas pipeline in the mixing chamber to form a combustible mixture. The combustible mixture is transported through the mixing chamber outlet to a second channel surrounding the first channel. The second channel includes an inlet section, a mixing section, and an outlet section. The combustible mixture is split once in the inlet section, so that it is evenly distributed around the inlet of the second channel. Then, the combustible mixture undergoes turbulent mixing in the mixing section, so that the fuel gas and the oxygen for combustion are fully mixed. Finally, the combustible mixture is split a second time in the outlet section, so that it is evenly distributed around the outlet of the second channel again, and then coaxially ejected around the laser beam, and ignited by the laser beam to form a flame. The laser beam, flame, and cutting oxygen are applied together to the workpiece cutting area to achieve laser-flame composite cutting.

2. The laser-flame composite cutting method based on gas distribution according to claim 1, characterized in that, During laser-flame composite cutting, the ratio of combustion gas pressure, oxygen pressure, and cutting oxygen pressure is 1:(8~12):(3~5); the ratio of laser power to cutting oxygen pressure is (0.5~3):1, where laser power is in kW and cutting oxygen pressure is in bar; and / or, During laser-flame composite cutting, the gas pressure is 0.4~0.6 bar, the combustion oxygen pressure is 4~6 bar, the cutting oxygen pressure is 1.5~2.5 bar, and the laser power is 1~6 kW.

3. The laser-flame composite cutting method based on gas distribution according to claim 1 or 2, characterized in that, After the combustible mixture is ignited by the laser beam to form a flame, the laser flame composite cutting method further includes: identifying the type of flame and making feedback adjustments based on the type of flame, specifically including the following steps: The spectral signal of the flame is acquired to determine the type of flame based on the spectral signal; When the flame type is determined to be a reduction flame, the current gas pressure is kept constant, and the pressure of the combustion-supporting oxygen is increased step by step with a preset step size. After each increase, the pressure is maintained for a preset stable time, and the flame type is re-determined. If the flame is switched to a neutral flame or an oxidizing flame during this process, the current proportioning parameters are maintained and the adjustment process ends. If the flame is still a reduction flame after the oxygen pressure for combustion increases to the preset safety upper limit, the increase of oxygen for combustion is stopped, and the pressure of the gas is gradually decreased in preset steps. After each decrease, the pressure is maintained for a preset stable time, and the type of flame is re-determined. If the flame switches to a neutral flame or an oxidizing flame during the process of reducing the gas pressure, the current ratio parameters are maintained and the adjustment process ends. If the flame remains a reduction flame after the gas pressure decreases to a preset lower limit, an abnormal protection procedure will be executed.

4. The laser-flame composite cutting method based on gas distribution according to claim 3, characterized in that, The increment of the oxygen pressure for combustion is 0.1 to 0.2 bar, and the settling time after each increment is 0.5 to 1 second. The gas pressure is decreased in increments of 0.02 to 0.05 bar, and the settling time after each decrease is 0.5 to 1 second.

5. The laser-flame composite cutting method based on gas distribution according to claim 3, characterized in that, While executing the step-by-step closed-loop adjustment process, the laser-flame composite cutting method also includes synchronously adjusting the laser power according to the degree of deviation of the flame type, specifically including: When the flame type is a reduction flame, the laser power is increased step by step with a preset step size, and after each increase, a preset stable time is maintained, and the flame type is re-determined; When the laser power increases to the preset safety limit, the increase in laser power will stop; When the flame type is switched to a neutral flame or an oxidizing flame, the laser power is restored to the initial setting value.

6. The laser-flame composite cutting method based on gas distribution according to claim 5, characterized in that, The preset step size for increasing laser power is 0.5~1 kW, and the preset stabilization time is 0.5~1 second.

7. The laser-flame composite cutting method based on gas distribution according to claim 3, characterized in that, A method for acquiring the current spectral signal of the flame and determining the current type of the flame based on the spectral signal includes: Extract the light intensity values ​​of the blue and yellow light bands of the flame, and calculate the light intensity ratio R of the blue and yellow light bands; when R is greater than the first threshold, it is determined to be a neutral flame; when R is less than the second threshold, it is determined to be a reducing flame; when R is between the first and second thresholds, it is determined to be an oxidizing flame. Wherein, the first threshold is greater than the second threshold.

8. A gas-distribution-based laser-flame composite cutting system, used in any one of the gas-distribution-based laser-flame composite cutting methods according to claims 1-7, characterized in that, include: An oxygen supply device, wherein the oxygen supply device has a first oxygen output terminal and a second oxygen output terminal; Cut the oxygen pipeline, connect the first oxygen output end to the first channel of the compound nozzle, and install a cutting oxygen proportioning valve on it. The combustion oxygen pipeline connects the second oxygen output end to the mixing chamber and is equipped with a combustion oxygen proportioning valve. A gas pipeline connects the gas source to the mixing chamber and is equipped with a gas proportional valve. The mixing chamber is used to receive and premix combustion-supporting oxygen and fuel gas to form a combustible mixture. Composite nozzle, including: The first channel, located in the middle, is used to allow the laser beam to pass through and receive cutting oxygen, so that the cutting oxygen is sprayed coaxially with the laser beam into the cutting area; The second channel, located outside the first channel, is used to transport the combustible mixture. The second channel is equipped with a primary beam splitting structure, a turbulence cavity, and a secondary beam splitting structure. A laser generator is used to generate a laser beam, which is transmitted through an optical path and then emitted from the first channel of the composite nozzle. The control unit is electrically connected to the gas proportional valve, the combustion oxygen proportional valve, the cutting oxygen proportional valve, and the laser generator, respectively.

9. The laser-flame composite cutting system based on gas distribution according to claim 8, characterized in that, It also includes a flame spectrum sensor installed on the composite nozzle. The flame spectrum sensor is electrically connected to the control unit. The control unit determines the type of flame based on the spectral signal collected by the flame spectrum sensor and outputs control commands to each proportional valve accordingly.

10. The laser-flame composite cutting system based on gas distribution according to claim 8 or 9, characterized in that, The primary beam splitting structure consists of multiple circumferentially evenly distributed primary beam splitting holes disposed in the entrance section of the second channel. The turbulence cavity is an annular cavity disposed in the mixing section of the second channel, and its inner diameter is larger than the inner diameter of the inlet section and the outlet section; The secondary beam splitting structure consists of multiple circumferentially evenly distributed axial channels located at the outlet section of the second channel. The inlet section, the mixing section, and the outlet section are connected in sequence, so that the combustible mixture passes through a first split, turbulent mixing, and a second split before being ejected coaxially around the first channel.

Images