Laser control method for thick plate hole making and system thereof

Abstract

The embodiment of the application provides a laser control method and system for thick plate hole forming, the control method comprising: determining a first parameter according to a to-be-processed thick plate, the first parameter comprising a first air pressure; controlling a laser device to cut at a target hole position of the to-be-processed thick plate with the first parameter to form a processing hole; controlling a laser beam of the laser device to move circumferentially around the processing hole with a second parameter, and controlling a laser focus of the laser beam to move based on a change of a hole depth of the processing hole until a through hole is formed, the second parameter comprising a second air pressure smaller than the first air pressure. The application realizes uniform energy input, orderly flow of a molten pool and efficient discharge of molten slag in the whole thick plate deep hole processing process by moving the laser focus with the hole depth and controlling the air pressure in stages, accurately suppresses problems such as large hole taper deviation, hole bottom slag, rough hole wall and wide heat affected zone, and guarantees forming precision, surface quality and processing consistency of the thick plate hole forming.

Description

Technical Field

[0001] This application relates to the field of laser processing technology, and in particular to a laser control method and system for drilling holes in thick plates. Background Technology

[0002] Laser drilling technology, with its advantages of non-contact processing, no tool wear, and high processing precision, has been widely used in shipbuilding, bridge steel structures, engineering machinery and other fields.

[0003] However, in existing laser processing methods for thicker plates, the laser energy attenuates significantly along the depth direction as the hole depth increases, resulting in insufficient melting of the bottom material, excessive hole taper, and poor consistency between the upper and lower hole diameters. Simultaneously, the disturbance of the molten pool by the airflow during processing easily leads to rough hole walls, and the concentrated local heat input results in a wide heat-affected zone. Summary of the Invention

[0004] In view of this, this application aims to provide a laser control method and system for making holes in thick plates, which solves the problems of excessive hole taper and poor consistency of upper and lower hole diameters.

[0005] In a first aspect, this application provides a laser control method for drilling holes in thick plates, comprising: Based on the thickness plate to be processed, determine the first parameter, which includes the first air pressure; The laser equipment is controlled to cut at the target hole position of the thick plate to be processed according to the first parameter, thereby forming a processing hole; The laser beam of the laser device is controlled to move around the circumference of the machined hole with a second parameter, and the laser focus of the laser beam is controlled to move based on the change in the depth of the machined hole until a through hole is formed. The second parameter includes a second air pressure that is less than the first air pressure.

[0006] In some implementations, the step of controlling the laser beam focus movement based on the change in hole depth specifically includes: The corrected focus position of the laser beam is determined based on the current hole depth and the preset control formula. The laser beam's focus is moved according to the corrected focus position; The preset control formula is: Z=Z0 k·h, where Z is the corrected focal position, Z0 is the initial focal position, h is the real-time hole depth, and k is the focal compensation coefficient.

[0007] In some implementations, the focus compensation coefficient k is calculated as follows: k = α·H / f, where H is the thickness of the plate to be processed, f is the depth of field of the laser beam, and α is an empirical correction coefficient.

[0008] In some embodiments, the step of controlling the laser beam of the laser device to move circumferentially around the machined hole with a second parameter specifically includes: The laser beam is controlled to move around the circumference of the machined hole using the hole-expanding air pressure; When the current hole depth meets the preset hole depth, the laser beam is controlled to move around the circumference of the hole with penetrating air pressure. The second pressure includes the orifice expansion pressure and the penetration pressure, with the first pressure > penetration pressure > orifice expansion pressure.

[0009] In some implementations, the permeation pressure is a pulsed permeation pressure with a pulse period of 0.2s to 1s.

[0010] In some implementations, the first pressure is 1.0 MPa to 1.3 MPa.

[0011] In some implementations, the orifice expansion pressure is 0.3 MPa to 0.7 MPa.

[0012] In some implementations, the permeation pressure is 0.7 MPa to 1.3 MPa.

[0013] In some embodiments, the laser control method further includes: The laser equipment is controlled to refine the wall of the through hole using a third parameter to obtain the target hole; The third parameter includes a third pressure that is less than the second pressure.

[0014] In some implementations, the third pressure is 0.2 MPa to 0.6 MPa.

[0015] In some implementations, the wall roughness Ra of the target hole is ≤0.3μm.

[0016] In some implementations, the first parameter further includes a first laser power, and the third parameter further includes a third laser power, wherein the third laser power is less than the first laser power.

[0017] In some implementations, the first laser power is 10kW to 14kW, and the third laser power is 4kW to 8kW.

[0018] Secondly, this application provides a laser control system for drilling holes in thick plates, comprising: The determining module is used to determine the first parameter based on the thickness plate to be processed, the first parameter including the first air pressure; The control module is used to control the laser equipment to cut at the target hole position of the thick plate to be processed with a first parameter to form a processing hole. The control module is also used to control the laser beam of the laser equipment to move around the processing hole circumferentially with a second parameter, and to control the laser focus of the laser beam to move based on the hole depth change of the processing hole until a through hole is formed. The second parameter includes a second air pressure that is less than the first air pressure.

[0019] Compared with the prior art, the beneficial effects of this application are: This application compensates for energy attenuation along the hole path by moving the laser focus with the hole depth, ensuring that the region with the highest laser energy density remains at the bottom of the hole. This allows for sufficient melting of the bottom of the plate, effectively reducing the diameter difference between the upper and lower surfaces of the hole and significantly decreasing the hole taper. Furthermore, by setting the second air pressure to be lower than the first air pressure, excessive disturbance of the auxiliary airflow to the molten pool is effectively reduced during the hole expansion stage, allowing the molten pool to solidify smoothly under low-disturbance conditions. This improves the surface finish of the hole wall and reduces the roughness of the hole wall. The synergistic effect of these two factors allows the hole to obtain controllable processing conditions in both the radial and axial directions, comprehensively improving the dimensional accuracy and forming quality of hole making in thick plates.

[0020] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 A flowchart illustrating a laser control method provided in one embodiment of this application; Figure 2 A schematic diagram illustrating the dynamic movement of the laser focus, provided for one embodiment of this application; Figure 3 A flowchart of a laser control method provided for another embodiment of this application; Figure 4 A flowchart of a laser control method provided for another embodiment of this application; Figure 5 This is a schematic diagram illustrating the effect of laser hole drilling using a traditional method. Figure 6 This is a schematic diagram illustrating the effect of a laser control method provided in one embodiment of this application; Figure 7 This is a structural block diagram of a laser control system provided in one embodiment of this application.

[0023] Explanation of reference numerals in the attached figures: 61 Laser equipment, 62 Thick plate to be processed. Detailed Implementation

[0024] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0025] In this application, the terms "upper," "lower," "left," "right," "front," "rear," "top," "bottom," "inner," "outer," "vertical," "horizontal," "lateral," and "longitudinal" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for the purpose of better describing this application and its embodiments, and are not intended to limit the indicated device, element, or component to having a specific orientation, or to be constructed and operated in a specific orientation.

[0026] Furthermore, in addition to indicating location or positional relationship, some of the aforementioned terms may also have other meanings. For example, the term "above" may also be used in some cases to indicate a certain dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0027] Furthermore, the terms "installation," "setup," "equipped with," "connection," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral structure; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium, or an internal connection between two devices, components, or parts. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0028] Furthermore, the terms "first," "second," etc., are primarily used to distinguish different devices, components, or parts (which may be the same or different in specific type and construction), and are not intended to indicate or imply the relative importance or quantity of the indicated devices, components, or parts. Unless otherwise stated, "a plurality of" means two or more.

[0029] Firstly, this application provides a laser control method for drilling holes in thick plates, such as... Figure 1 As shown, it includes: S100, based on the thickness plate to be processed, determine the first parameter, which includes the first air pressure.

[0030] The thick plate 62 to be processed is a steel plate workpiece with a thickness of 10mm or more.

[0031] The first parameter is a set of process parameters for laser processing in the initial piercing stage, including at least laser power, cutting speed, initial gas pressure, and focal point position. Specifically, the initial gas pressure is the pressure value of the auxiliary gas used in the initial piercing stage, measured in MPa. The auxiliary gas plays a crucial role in laser hole making, including removing molten metal, protecting the molten pool, and preventing oxidation. The selection of the initial gas pressure must balance initial piercing efficiency with the quality of the hole's formation.

[0032] This step is used to determine the process parameters based on the actual conditions of the thick plate 62 to be processed before processing.

[0033] S200 controls the laser equipment to cut at the target hole position of the thick plate to be processed with the first parameter to form a processing hole.

[0034] A machined hole refers to a temporary hole formed by laser processing during the hole-making process. The geometry of the machined hole changes dynamically as the processing progresses. The geometry of the machined hole includes the hole diameter and the hole depth. The target hole position is the preset hole center position on the thick plate 62 to be processed.

[0035] This step is the initial piercing stage, which involves performing the initial piercing action. This step is used to quickly establish the orifice channel and the initial molten pool structure, providing a foundation for subsequent hole enlargement processing.

[0036] S300, the laser beam of the laser device is controlled to move around the circumference of the machined hole with a second parameter, and the laser focus of the laser beam is controlled to move based on the change in the depth of the machined hole until a through hole is formed. The second parameter includes a second air pressure that is less than the first air pressure.

[0037] The second parameter is the set of process parameters for hole enlargement and subsequent processing stages. The laser beam scans and cuts along the circumference of the hole, so that the laser energy is evenly distributed along the hole circumference. The circumferential movement avoids the long-term concentration of energy at the same position, so that the molten pool is formed synchronously and evenly along the hole circumference, avoiding local energy concentration, which is conducive to maintaining the roundness of the hole and achieving a stable enlargement of the hole diameter.

[0038] Optionally, the second air pressure is the auxiliary air pressure value used in the hole expansion and subsequent stages, and the second air pressure is less than the first air pressure.

[0039] The laser focus is the beam waist position where the laser beam has the highest energy density and the smallest spot diameter after focusing. The hole depth is the vertical distance from the top surface of the plate to the bottom of the hole. The laser focus position is actively adjusted as the hole depth increases, with the focus moving downwards from the initial position into the depth of the plate. This application correlates the laser focus position with the real-time hole depth, causing the laser focus to actively move downwards into the depth of the plate as the hole depth increases. This keeps the area with the most concentrated laser energy near the bottom of the hole, compensating for energy attenuation along the path and ensuring that the material in the lower part of the plate receives sufficient energy density to achieve complete melting, avoiding an uneven state of over-melting at the top and under-melting at the bottom.

[0040] This application avoids excessive laser power increase to ensure bottom melting through dynamic focus compensation, effectively suppresses local heat accumulation in the processing area, avoids problems such as grain coarsening and material softening caused by high temperature in traditional processes, preserves the original metallographic structure and mechanical properties of the substrate to the greatest extent, and reduces the deterioration of local strength and toughness in the hole-making area.

[0041] In this application, the circumferential motion of the laser beam and the movement of the laser focus with the hole depth are executed synchronously in time. The circumferential motion ensures uniform expansion in the hole diameter direction, and the movement of the laser focus ensures energy supply in the hole depth direction. The two work together to enable the hole to obtain controllable processing conditions in both radial and depth dimensions, providing a basis for achieving through holes with low taper, high roundness, and consistent hole diameter. This application avoids excessively increasing the laser power to ensure bottom melting through dynamic focus compensation, effectively suppressing local heat accumulation in the processing area, controlling the range of the heat-affected zone, and reducing thermal damage to the mechanical properties of the substrate.

[0042] Simultaneously, the second gas pressure is lower than the first gas pressure, meaning the second gas pressure during the reaming and subsequent stages is lower than the first gas pressure during the initial piercing stage. In the initial piercing stage, high gas pressure helps to quickly blow the initial molten metal away from the orifice area, preventing slag accumulation at the orifice. After entering the reaming stage, the hole depth increases, and the molten pool is located deep at the bottom of the hole. If high gas pressure continues to be used at this point, the airflow will generate violent turbulence within the narrow channel, causing excessive impact on the surface of the molten pool, resulting in oscillations of the molten pool surface and ripples on the solidified hole wall surface. This application reduces the second gas pressure during the reaming and subsequent stages, weakening the dynamic disturbance of the airflow to the molten pool, which is beneficial for the molten pool to flow smoothly and gradually solidify under low-disturbance conditions, thereby forming a smooth and flat hole wall.

[0043] This application compensates for energy attenuation along the hole path by moving the laser focus with the hole depth, ensuring that the region with the highest laser energy density remains at the bottom of the hole. This allows for sufficient melting of the bottom of the plate, effectively reducing the diameter difference between the upper and lower surfaces of the hole and significantly decreasing the hole taper. Furthermore, by setting the second air pressure to be lower than the first air pressure, excessive disturbance of the auxiliary airflow to the molten pool is effectively reduced during the hole expansion stage, allowing the molten pool to solidify smoothly under low-disturbance conditions. This improves the surface finish of the hole wall and reduces the roughness of the hole wall. The synergistic effect of these two factors allows the hole to obtain controllable processing conditions in both the radial and axial directions, comprehensively improving the dimensional accuracy and forming quality of hole making in thick plates.

[0044] In some implementations, the step of controlling the laser beam focus movement based on the change in hole depth during machining, such as... Figure 3 As shown, it specifically includes: S302, determine the corrected focus position of the laser beam based on the current hole depth and the preset control formula.

[0045] The current hole depth is the measured or estimated vertical distance from the top surface of the plate to the bottom of the hole at the current processing moment.

[0046] The preset control formula is a pre-defined function for calculating the focal position with the hole depth as the independent variable. The preset control formula is: Z=Z0 k·h.

[0047] Z represents the corrected focal position, which is the real-time target coordinate value of the laser focal point along the optical axis.

[0048] Z0 is the initial focal position, which is the initial coordinate position of the focal point relative to the upper surface of the workpiece at the start of machining. It is determined before machining and remains unchanged throughout the machining process, serving as the starting reference point for focal point movement. It should be noted that the specific value of Z0 can be set as a positive offset, zero position, or negative offset according to actual machining requirements.

[0049] h represents the real-time hole depth, a dynamically changing value that increases continuously as the processing progresses. The real-time hole depth can be obtained through methods such as processing time estimation, sensor detection, or estimation based on a material removal rate model. It can be understood that h gradually increases from 0 to the plate thickness H. The real-time hole depth can be obtained through methods such as processing time estimation, sensor detection, or estimation based on a material removal rate model.

[0050] k is the focus compensation coefficient. The larger the value of k, the faster the laser focus moves downward with increasing aperture depth; the smaller the value of k, the slower the downward movement. The value of k needs to be determined based on factors such as the thickness of the substrate and the beam characteristics.

[0051] When h=0, Z=Z0, meaning the laser focus is located at the initial preset position, and no focus compensation is required at the start of the corresponding processing time.

[0052] When h>0, Z<Z0, that is, the laser focus moves from the initial position into the interior of the plate. The downward movement speed of the focus is proportional to the increasing speed of the hole depth, with the proportional coefficient being k, so that the focus is always at a position matching the current hole depth at each processing moment.

[0053] Alternatively, the movement modes of the laser focus include a continuous downward movement mode or a segmented jumping mode. The continuous downward movement mode means that the laser focus moves smoothly and continuously into the deep part of the plate as the hole depth increases. The segmented jumping mode means that the laser focus jumps stepwise into the deep part of the plate according to preset depth intervals. Both movement modes can achieve effective compensation of laser energy in the deep hole area, and can be determined according to the control accuracy of the laser device 61 and actual process requirements.

[0054] as Figure 2 shown, Figure 2 , (a) shows that the laser focus is at the initial preset position, at this time the hole depth h=0mm, Z=Z0.

[0055] Figure 2 , from (b) to (e), it can be seen that the hole depth h increases and the position Z of the laser focus moves downward.

[0056] Specifically, in Figure 2 , (b), h1=4mm, Z=Z0-k·h1.

[0057] In Figure 2 , (c), h2=8mm, Z=Z0-k·h2.

[0058] In Figure 2 , (d), h3=12mm, Z=Z0-k·h3.

[0059] In Figure 2 , (e), h4=16mm, Z=Z0-k·h4.

[0060] S304, controlling the movement of the laser focus of the laser beam according to the corrected focus position.

[0061] Taking the calculated corrected focus position as a target command to drive the laser focus to move to the corrected focus position.

[0062] In this embodiment, the preset regulation formula realizes the precise and controllable adjustment of the laser focus position along with the hole depth. Through Z=Z0 -k·h, the established linear mapping relationship keeps the downward movement rate of the focus stable, avoids lag or overshoot in focus position adjustment, and improves the accuracy of energy compensation and process repeatability in the thick plate drilling process.

[0063] In some implementations, the formula for calculating the focus compensation coefficient k is: k = α·H / f, where H is the thickness of the plate to be processed 62, f is the depth of field of the laser beam, and α is an empirical correction coefficient.

[0064] In this embodiment, the focus compensation coefficient k is quantitatively correlated with the plate thickness H and the beam depth of field f. The greater the plate thickness H, the deeper the laser needs to penetrate, and the greater the total travel distance of the focus as the aperture depth decreases; k is directly proportional to H. Conversely, the greater the beam depth of field f, the wider the range of energy concentration maintained by the laser beam in the depth direction, and the relatively lower the sensitivity to focus position accuracy; k is inversely proportional to f.

[0065] In this embodiment, by setting a formula for calculating the focus compensation coefficient k, the determination of the focus compensation coefficient is transformed from relying on empirical trial and error to quantitative calculation based on deterministic physical parameters, significantly improving the scientific nature and repeatability of k value selection. Introducing the beam depth of field f into the calculation of the k value directly links the focus compensation strategy to the physical characteristics of the laser beam itself, ensuring the matching between the focus movement scheme and the optical system parameters, and avoiding the problem of mismatch between the focus position and beam energy distribution caused by blindly setting the k value.

[0066] It should be noted that the formula for calculating the beam depth of field f is: f=2πω0² / λ, where ω0 is the beam waist radius of the laser beam and λ is the laser wavelength. The above parameters are the basic parameters of the optical system of the laser device 61, which can be determined during the equipment selection and optical path design stages.

[0067] The empirical correction factor α can be calibrated by conducting multiple sets of orthogonal experiments under given equipment and material conditions. The calibration method for the empirical correction factor α is as follows: under given material and equipment conditions, conduct hole-making experiments with multiple sets of different α values, using indicators such as hole taper and hole wall roughness as evaluation criteria, and select the α value with the optimal overall processing effect as the standard value under those conditions. The value of α is usually between 0.8 and 1.2, and can be adjusted according to factors such as the material's laser absorption characteristics and differences in thermal conductivity.

[0068] In some embodiments, the step of controlling the laser beam of the laser device 61 to move circumferentially around the machined hole with a second parameter, such as Figure 4 As shown, it specifically includes: The second pressure includes the orifice-expanding pressure and the penetration pressure, with the first pressure > penetration pressure > orifice-expanding pressure. This stage includes an orifice-expanding stage and a penetration stage. The orifice-expanding stage uses the orifice-expanding pressure, and the penetration stage uses the penetration pressure.

[0069] S306 controls the laser beam to move circumferentially around the machined hole using the hole-expanding air pressure.

[0070] During the hole enlargement stage, the hole is machined using a combination of enlargement gas pressure and the circumferential motion of the laser beam. The circumferential motion of the laser beam ensures that the laser energy is evenly distributed along the hole circumference, achieving a smooth increase in hole diameter. Simultaneously, the relatively low enlargement gas pressure used during this stage minimizes the impact on the molten pool, allowing it to flow and solidify under low-disturbance conditions. This promotes the formation of a smooth and flat hole wall surface, ensuring the quality of the hole wall formation and laying a solid foundation for subsequent penetration.

[0071] S308, based on the current hole depth of the machined hole meeting the preset hole depth, controls the laser beam to move around the circumference of the machined hole with penetrating air pressure.

[0072] The preset hole depth is a pre-defined threshold value used to determine whether the hole enlargement stage has ended and whether the process should switch to the penetration stage. The preset hole depth can be set according to the thickness of the board material; for example, the preset hole depth can be 90% to 95% of the board thickness, which triggers the stage switch just before the hole is about to penetrate.

[0073] When the hole depth is less than the preset depth, the bottom of the hole has not yet approached the lower surface of the plate, and there is no need to forcefully flush the slag at this time. When the hole depth reaches or exceeds the preset depth, it indicates that the bottom of the hole is close to the bottom of the plate and penetration is imminent. At this time, the processing is switched from the hole-expanding air pressure to the penetration air pressure, which enhances the flushing ability of the slag at the bottom of the hole, ensuring that the material at the bottom is carried out of the hole by the airflow as soon as it is melted, and avoiding solidification and slag formation at the bottom of the hole.

[0074] It should be noted that during the initial perforation stage, the laser acts on the entire surface of the plate, and the amount of molten metal is large and located near the hole opening. A high initial air pressure is required to quickly blow it away from the hole opening area to prevent molten slag from accumulating at the hole opening and affecting subsequent processing.

[0075] As the reaming stage begins, the hole depth gradually increases, and the molten pool is located deep within the pore. At this point, the gas pressure is reduced to the minimum reaming pressure to prevent the high-pressure gas flow in the narrow, deep pore channel from generating severe turbulence that impacts and fluctuates the molten pool surface, leading to ripples and increased roughness on the solidified pore wall surface. Lower reaming pressure reduces the impact and disturbance of the gas flow on the molten pool, allowing it to solidify gradually under low-disturbance conditions, thus achieving a smooth pore wall.

[0076] Once the hole depth meets the preset depth, the penetration stage begins. The air pressure is increased to the penetration pressure. During the penetration stage, the bottom of the hole is about to penetrate the bottom of the plate. The molten slag at the bottom needs to be discharged from the hole under the combined action of gravity and airflow. The penetration pressure, which is higher than the hole-expanding air pressure, provides sufficient airflow scouring force to carry out the molten metal and residual slag from the bottom of the hole, reducing slag buildup at the bottom of the hole.

[0077] In this embodiment, the circumferential motion of the laser beam is subdivided into a hole-expanding stage and a penetration stage, and different air pressure values ​​are matched for different stages. This makes the control method of the auxiliary air pressure adapt to the depth of the processing process. Each stage is carried out under air pressure conditions that match its process requirements, thereby improving processing accuracy and forming quality.

[0078] It is worth noting that this application uses a phased control of air pressure and a synchronous control method that allows the laser focus to move continuously with the hole depth, so that energy compensation and slag removal optimization can be promoted synchronously on the time axis and work together on different processing stages of the same hole, thereby comprehensively improving the dimensional accuracy, hole wall quality and hole bottom integrity of thick plate holes.

[0079] In some implementations, the penetration pressure is a pulsed penetration pressure. During the penetration stage, the bottom of the hole is about to penetrate the bottom of the plate, and molten metal and slag concentrate in the bottom area of ​​the hole. The pulsed gas supply provides an impact force during the high-pressure period to blow the slag away from the bottom of the hole, and stops the gas supply during the intermittent period to avoid excessive disturbance to the molten pool caused by continuous airflow impact, while allowing the molten pool to achieve temporary stability during the intermittent period.

[0080] In some implementations, the pulse period of the pulsed through-pressure gas is 0.2s to 1s. If the pulse period is too short, the high-pressure period is insufficient to form an effective impact slag removal effect; if the pulse period is too long, the intermittent period may lead to excessive cooling of the molten pool, which in turn affects the slag removal fluidity.

[0081] In some embodiments, the first pressure is 1.0 MPa to 1.3 MPa. Optionally, the first pressure is 1.0 MPa.

[0082] In some embodiments, the expansion pressure is 0.3 MPa to 0.7 MPa. Optionally, the expansion pressure is 0.6 MPa.

[0083] In some embodiments, the penetration pressure is 0.7 MPa to 1.3 MPa. Optionally, the penetration pressure is 1.1 MPa.

[0084] In some implementations, such as Figure 1 As shown, the laser control method also includes: S400 controls the laser equipment to refine the wall of the through hole using a third parameter to obtain the target hole. The third parameter includes a third air pressure lower than the second air pressure.

[0085] Fine finishing refers to the process of scanning and polishing along the hole wall using a low-power laser after the hole has been fully penetrated. This process eliminates residual ripples, molten burrs, and localized forming defects on the hole wall surface from the previous processing. The target hole is the finished hole that has achieved the final dimensional accuracy and surface quality requirements after fine finishing. The third gas pressure is the auxiliary gas pressure value used in the fine finishing stage, and its value is lower than the second gas pressure.

[0086] During the finishing process, a low-power laser scans the hole wall at a short, uniform speed. The laser energy acts only on the micro-protrusion areas on the hole wall surface, causing them to remelt and flow smoothly under surface tension, thereby eliminating machining marks on the hole wall and reducing the thickness of the resolidified layer. The micro-protrusion areas include ripple peaks, molten burrs, and localized rough layers.

[0087] Simultaneously, by fine-tuning the focal point position and auxiliary gas pressure, local aperture deviations caused by molten pool fluctuations or uneven energy during the initial processing can be compensated and corrected, thus optimizing aperture consistency. After the hole enlargement and penetration stages, defects such as micro-ripples, localized slag residue, and resolidified layers may exist on the hole wall surface due to unstable molten pool flow. In this embodiment, short-time uniform-speed laser scanning polishing can remelt and level the surface protrusions, thereby eliminating the aforementioned defects.

[0088] The third gas pressure is lower than the second gas pressure, meaning the gas pressure in the finishing stage is further reduced to a level lower than that in the hole enlargement and penetration stages. Because the laser power is low in the finishing stage, the amount of molten metal produced is minimal, eliminating the need for high-pressure gas for slag removal. The low gas pressure only requires a basic protective atmosphere and slight purging to meet the requirements. Furthermore, the low gas pressure causes minimal disturbance to the molten pool, which is beneficial for forming a high-quality, smooth surface.

[0089] Optionally, during the process of switching from the expansion gas pressure to the penetration gas pressure, a gradual pressure increase method is adopted so that the gas pressure rises slowly to the target penetration gas pressure value within a preset time, thereby avoiding sudden gas pressure changes that could cause impact disturbance to the molten pool at the bottom of the hole.

[0090] Optionally, when switching from the penetration stage to the hole-repairing stage, a gradual pressure reduction method is adopted to ensure a smooth transition of gas pressure in each stage.

[0091] In some implementations, the third pressure is 0.2 MPa to 0.6 MPa.

[0092] In some implementations, the wall roughness Ra of the target hole is ≤0.3μm.

[0093] In some implementations, the first parameter further includes a first laser power, and the third parameter further includes a third laser power, wherein the third laser power is less than the first laser power.

[0094] The first laser power characterizes the laser power during the initial perforation stage. The third laser power characterizes the laser power during the finishing process.

[0095] Finishing is the final finishing process performed on the hole wall after the hole has been completely penetrated, at which point the hole diameter and shape are determined. If the same or higher laser power as in the initial perforation stage is used, the laser energy will not only melt the surface micro-protrusions but also excessively melt the hole wall substrate, leading to hole enlargement, hole shape misalignment, and even excessive thermal damage to the hole wall. Low-power lasers have shallow penetration depth and a small heat-affected zone, acting only on a micron-thick area of ​​the surface, enabling precise and controllable micro-finishing without affecting the already formed hole geometry.

[0096] In some implementations, the first laser power is 10kW to 14kW, and the third laser power is 4kW to 8kW.

[0097] The first laser power should be between 10kW and 14kW. Within this power range, sufficient energy density can be provided to rapidly melt the surface layer of a 10mm to 20mm thick sheet material and form the initial hole during the initial piercing stage. If the first laser power is below 10kW, the energy density is insufficient to fully melt the surface material within a reasonable time, resulting in low initial piercing efficiency. If the first laser power is above 14kW, excessive energy input will exacerbate hole spatter and expand the heat-affected zone, affecting the hole formation quality.

[0098] The third laser power ranges from 4kW to 8kW, approximately 40% to 60% of the first laser power. The finishing stage only requires a small amount of melting to the micro-protrusions on the hole wall surface. The low-power laser has a shallow penetration depth, acting only on areas with a micron-level thickness on the surface, without altering the already formed hole diameter and shape. Simultaneously, it avoids excessive thermal damage to the hole wall substrate caused by high power. This power range, combined with the gas pressure range of the finishing stage, works synergistically to ensure a high-quality, smooth surface is obtained during the finishing process.

[0099] As shown in Table 1, a total of 25 samples (numbered 1 to 25) were provided, and comparative experiments were conducted on thick plates using two different process schemes for laser hole drilling: The comparative experiment used a traditional method, with the following experimental conditions: fixed laser focus and constant auxiliary gas pressure.

[0100] The embodiment uses the laser hole-making control method provided in this application, and the test conditions are dynamic focus adjustment and segmented air pressure control.

[0101] The test parameters include: hole taper (°) and hole wall surface roughness (μm).

[0102] The object to be processed is a Q355 steel plate with a thickness of 16mm and a target hole diameter of 16mm.

[0103] Table 1

[0104] like Figure 5 As shown in the comparative example, the fixed focus method causes the laser energy to attenuate along the depth of the hole. The energy density is high near the hole opening, and the material is fully melted. As the hole depth increases to the bottom region, the energy density is insufficient to fully melt the material, resulting in an increase in the difference between the upper and lower hole diameters and an increase in the hole taper.

[0105] like Figure 6 As shown, the embodiment employs dynamic focus adjustment, with the laser focus varying with the hole depth according to Z=Z0. The continuous downward movement of kh keeps the area of ​​highest energy concentration near the bottom of the hole, compensating for energy attenuation in the deep hole direction, ensuring that the bottom material of the 16mm plate is fully melted, effectively reducing the difference between the upper and lower hole diameters, and reducing the hole taper by about 48.7%.

[0106] like Figure 5 As shown, in the comparative example, the constant high-pressure airflow generates continuous turbulence in the deep hole channel, causing continuous impact and oscillation on the surface of the molten pool at the bottom of the hole, resulting in wavy undulations on the surface of the hole wall after solidification. The insufficient energy at the bottom caused by the fixed focal point further exacerbates the non-uniformity of the hole wall formation.

[0107] like Figure 6 As shown, the embodiment employs segmented air pressure control. During the hole enlargement stage, the air pressure is reduced from its initial value, weakening the excessive disturbance of the molten pool by the airflow and allowing the hole wall to be smoothly formed under low-disturbance conditions. During the penetration stage, pulsed high-pressure slag removal is used to ensure effective removal of molten slag from the bottom of the hole without affecting the already formed hole wall. During the hole finishing stage, low-power, low-pressure fine polishing is used. The synergy of these three methods reduces the hole wall roughness by approximately 42.6%.

[0108] The range of hole taper in the comparative example was 0.026, while that in the example was 0.014, a reduction of approximately 46.2% in fluctuation. The range of roughness in the comparative example was 0.73, while that in the example was 0.31, a reduction of approximately 57.5% in fluctuation. The ranges of both sets of data narrowed significantly, indicating that the synergistic scheme of dynamic focus adjustment and segmented air pressure control effectively overcomes the problem of processing effect dispersion caused by energy attenuation and airflow disturbance in traditional fixed focus and constant air pressure processes. The improved consistency of hole quality among samples directly reduces dimensional deviations and rework rates in multi-batch, multi-hole processing, providing process stability assurance for industrial mass production.

[0109] This application effectively improves single-hole size deviation and multi-hole processing differences through full-process dynamic energy compensation and fine-tuning control. It has high hole diameter accuracy and good consistency, and can be directly matched with standard fasteners for installation, thereby improving the structural assembly accuracy and fitting reliability.

[0110] This application significantly reduces hole-making defects and rework frequency, eliminating the need for subsequent grinding, hole repair, and other secondary processing steps. It boasts high processing efficiency and high yield, effectively reducing the production and maintenance costs of deep hole machining in thick plates and is suitable for industrialized mass production.

[0111] Secondly, this application provides a laser control system 500 for drilling holes in thick plates, such as... Figure 7 As shown, it includes: The determining module 502 is used to determine a first parameter based on the thick plate 62 to be processed, the first parameter including a first air pressure; The control module 504 is used to control the laser device 61 to cut at the target hole position of the thick plate 62 to be processed with a first parameter to form a processing hole. The control module 504 is also used to control the laser beam of the laser device 61 to move around the processing hole circumferentially with a second parameter, and to control the laser focus of the laser beam to move based on the hole depth change of the processing hole until a through hole is formed. The second parameter includes a second air pressure that is less than the first air pressure.

[0112] The laser control system 500 is an automated control device for performing thick plate laser drilling process, and includes various functional modules required to implement the method of the present invention.

[0113] The determining module 502 is a software or hardware unit used to determine the processing parameters based on the input parameters, and its output is the first parameter. Specifically, the input parameters include the material of the sheet metal, its thickness, the target hole diameter, etc.

[0114] The control module 504 is a software or hardware unit used to send control commands to the laser device 61 to execute processing actions. Its control logic includes initial piercing, dynamic focus compensation, and circumferential hole enlargement movement.

[0115] The laser control system 500 provided in this application can automatically determine the initial processing parameters according to the actual conditions of the thick plate 62 to be processed, realizing the standardization and automation of process parameter setting, avoiding parameter deviation and individual differences caused by human experience judgment, and can automatically execute a series of actions such as initial perforation, dynamic movement of the focal spot with the hole depth, and circumferential expansion of the laser beam, realizing the automated control of the entire process of hole making in thick plates, and reducing the dependence on the skill level of the operator.

[0116] This application compensates for energy attenuation along the hole path by moving the laser focus with the hole depth, ensuring that the region with the highest laser energy density remains at the bottom of the hole. This allows for sufficient melting of the bottom of the plate, effectively reducing the diameter difference between the upper and lower surfaces of the hole and significantly decreasing the hole taper. Furthermore, by setting the second air pressure to be lower than the first air pressure, excessive disturbance of the auxiliary airflow to the molten pool is effectively reduced during the hole expansion stage, allowing the molten pool to solidify smoothly under low-disturbance conditions. This improves the surface finish of the hole wall and reduces the roughness of the hole wall. The synergistic effect of these two factors allows the hole to obtain controllable processing conditions in both the radial and axial directions, comprehensively improving the dimensional accuracy and forming quality of hole making in thick plates.

[0117] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A laser control method for drilling holes in thick plates, characterized in that, include: Based on the thickness plate to be processed, a first parameter is determined, the first parameter including a first air pressure; The laser equipment is controlled to cut at the target hole position of the thick plate to be processed using the first parameters to form a processing hole; The laser beam of the laser device is controlled to move circumferentially around the processing hole with a second parameter, and the laser focus of the laser beam is controlled to move based on the change in the hole depth of the processing hole until a through hole is formed. The second parameter includes a second air pressure that is less than the first air pressure.

2. The laser control method according to claim 1, characterized in that, The step of controlling the laser beam focus movement based on the hole depth variation of the processed hole specifically includes: The corrected focus position of the laser beam is determined based on the current hole depth and the preset control formula. Based on the corrected focal position, control the movement of the laser beam's focal point; The preset control formula is: Z=Z0 k·h, where Z is the corrected focal position, Z0 is the initial focal position, h is the real-time hole depth, and k is the focal compensation coefficient.

3. The laser control method according to claim 2, characterized in that, The formula for calculating the focus compensation coefficient k is: k = α·H / f, where H is the thickness of the plate to be processed, f is the depth of field of the laser beam, and α is an empirical correction coefficient.

4. The laser control method according to claim 1, characterized in that, The step of controlling the laser beam of the laser device to move circumferentially around the machining hole with a second parameter specifically includes: The laser beam is controlled to move circumferentially around the machined hole using hole-expanding air pressure; When the current hole depth of the machined hole meets the preset hole depth, the laser beam is controlled to move circumferentially around the machined hole with penetrating air pressure; The second air pressure includes the orifice expansion air pressure and the penetration air pressure, wherein the first air pressure > the penetration air pressure > the orifice expansion air pressure.

5. The laser control method according to claim 4, characterized in that, The penetrating pressure is a pulsed penetrating pressure, and the pulse period of the pulsed penetrating pressure is 0.2s~1s; and / or, The first air pressure is 1.0 MPa to 1.3 MPa; and / or, The orifice expansion pressure is 0.3 MPa to 0.7 MPa; and / or, The permeation pressure is 0.7MPa~1.3MPa.

6. The laser control method according to any one of claims 1 to 5, characterized in that, The laser control method further includes: The laser device is controlled to perform fine finishing on the wall of the through hole using a third parameter to obtain the target hole; The third parameter includes a third air pressure that is lower than the second air pressure.

7. The laser control method according to claim 6, characterized in that, The third pressure is 0.2 MPa to 0.6 MPa; and / or, The wall roughness Ra of the target hole is ≤0.3μm.

8. The laser control method according to claim 6, characterized in that, The first parameter also includes a first laser power, and the third parameter also includes a third laser power, wherein the third laser power is less than the first laser power.

9. The laser control method according to claim 8, characterized in that, The first laser power is 10kW~14kW, and the third laser power is 4kW~8kW.

10. A laser control system for drilling holes in thick plates, characterized in that, include: The determining module is used to determine a first parameter based on the thick plate to be processed, wherein the first parameter includes a first air pressure; The control module is used to control the laser device to cut the target hole in the thick plate to be processed with the first parameter to form a processing hole. The control module is also used to control the laser beam of the laser device to move around the processing hole circumferentially with the second parameter, and to control the laser focus of the laser beam to move based on the hole depth change of the processing hole until a through hole is formed. The second parameter includes a second air pressure that is less than the first air pressure.

Images