Coaxial laser heating and dynamic temperature control galvanometer scanning laser processing system and method

Abstract

The invention discloses a galvanometer scanning laser processing system and method for coaxial laser heating and dynamic temperature control, and belongs to the technical field of laser additive manufacturing. The system comprises a main processing laser module, a preheating light path module, a coaxial beam combining and scanning module, a temperature control monitoring light path module and an intelligent control system. The preheating light path module and the light beam shaping lens group generate uniform flat-topped light spots through a specific light path, the coaxial beam combining and scanning module achieves coaxial output of main machining laser and preheating laser, the temperature control monitoring light path module monitors the temperature in real time, and the intelligent control system executes dynamic temperature closed-loop control. According to the method, machining is completed through path planning, parameter setting, preheating starting, temperature control closed loop establishment, synchronous machining and layer-by-layer circulation. Accurate and uniform preheating and dynamic temperature control of the machining area can be achieved, residual stress and process defects are remarkably restrained, the part forming quality is improved, and the method is particularly suitable for high-quality machining of nickel-based high-temperature alloy and other materials difficult to machine.

Description

Technical Field

[0001] This invention belongs to the field of intelligent laser heating welding technology, and particularly relates to a galvanometer scanning laser processing system and method with coaxial laser heating and dynamic temperature control. Background Technology

[0002] In the field of laser additive manufacturing technology, selective laser melting, selective laser sintering, and laser-engineered net forming have become key technologies for fabricating complex structural parts, widely used in aerospace, medical devices, and high-end equipment manufacturing. However, during the printing process, the printing material undergoes a rapid melting and solidification thermodynamic process, inevitably generating a significant temperature gradient. This leads to a series of technical bottlenecks, severely restricting the quality and performance of the formed parts. Specific problems are as follows: Residual stress and structural deformation are prominent issues: During rapid phase transformation of materials, the degree of thermal expansion and contraction varies significantly in different regions, resulting in high residual stress inside the parts. This stress can easily cause warping and cracking of parts during printing. After molding, it is not only difficult to meet the design dimensional accuracy requirements, but it also significantly reduces the fatigue life and mechanical reliability of the parts, especially for thin-walled and complex-shaped parts.

[0003] Frequent process defects lead to performance degradation: drastic fluctuations in temperature gradients can disrupt the stability of the molten pool, causing defects such as powder splashing and spheroidization of the melt channel. These defects directly lead to a decrease in the density of the molded parts, forming microscopic defects such as internal pores and inclusions, which in turn weaken the key mechanical properties of the parts, such as tensile strength and impact toughness, making them unable to meet the requirements of high-load and high-reliability applications.

[0004] Application of difficult-to-process materials is limited: For materials with excellent high-temperature performance and mechanical properties, such as high-strength steel, high-temperature alloys, and titanium alloys, their thermal conductivity is low and their thermal cracking sensitivity is high. Traditional laser additive manufacturing processes cannot effectively control the temperature field, and thermal cracks are easily generated during the printing process. This makes it difficult to achieve efficient and high-quality molding of such key materials through additive manufacturing technology, which limits the range of materials to be selected for core components of high-end equipment.

[0005] To alleviate the above problems, existing technologies generally employ preheating solutions such as overall substrate heating or setting up an independent infrared preheating furnace within the processing chamber. However, these solutions have significant technical shortcomings: First, preheating efficiency is low and energy consumption is high, requiring the entire substrate or processing chamber to be heated to hundreds of degrees Celsius, which not only consumes a large amount of energy but also requires lengthy heating and holding times, severely reducing production efficiency. Second, preheating precision is insufficient; the overall preheating method cannot accurately control the temperature of the printed micro-area, resulting in poor uniformity of the temperature field distribution. Especially in large-size processing areas, the temperature fluctuation range in different areas can reach tens of degrees Celsius, making it difficult to meet the requirements of high-precision printing. Third, there are system complexity and compatibility issues; independent preheating systems require additional equipment space, and their optical paths and thermal fields are prone to interference with the main laser processing system, increasing the difficulty of equipment debugging and the failure rate. Fourth, the preheating effect is unsatisfactory; the uneven energy distribution of the heating source in existing preheating methods results in the continued existence of temperature gradients in the preheated area, failing to fundamentally solve the problems of residual stress and process defects.

[0006] In summary, existing preheating solutions in laser additive manufacturing technology are insufficient to meet the processing requirements of high precision, high efficiency, and high quality. There is an urgent need in this field for a preheating technology solution that can achieve synergistic processing of micro-areas and the entire printing area, real-time precise temperature control, and uniform energy distribution, in order to break through existing technical bottlenecks and promote the development of laser additive manufacturing technology towards high quality and high reliability. Summary of the Invention

[0007] The purpose of this invention is to provide a galvanometer scanning laser processing system and method with coaxial laser heating and dynamic temperature control, so as to solve the problems mentioned in the background art.

[0008] In view of this, the present invention provides a coaxial laser heating and dynamic temperature control galvanometer scanning laser processing system, including a main processing laser module, a preheating optical path module, a coaxial beam combining and scanning module, a temperature control monitoring optical path module, and an intelligent control system. The main processing laser module is used to output a high-energy main processing laser to melt the printing material. The preheating optical path module is used to generate a preheating spot with uniform energy and controllable size and guide it to the processing area. The coaxial beam combining and scanning module is used to realize the coaxial output and scanning of the main processing laser and the preheating laser. The temperature control monitoring optical path module is used to monitor the temperature field around the preheating area and the molten pool in real time. The intelligent control system is electrically connected to the main processing laser module, the preheating optical path module, the coaxial beam combining and scanning module, and the temperature control monitoring optical path module to realize dynamic temperature closed-loop control and collaborative operation of each module.

[0009] In a further embodiment of the present invention, the preheating optical path module includes a preheating laser, a mirror group, a beam combiner, a beam shaping mirror group, and a focusing mirror. The mirror group includes a first mirror and a second mirror. The beam shaping mirror group is used to shape the energy distribution of the preheating laser into a flat-top light spot. The beam shaping method includes any one of the following: microlens homogenization method, integrating mirror method, homogenizing rod method, and homogenizing fiber method. The laser output from the preheating laser is sequentially shaped by the mirror group, the first beam combiner, the beam shaping mirror group, and focused by the focusing mirror before being guided to the coaxial beam combining and scanning module.

[0010] In a further embodiment of the present invention, the coaxial beam combining and scanning module includes a second beam combiner, a first galvanometer, a second galvanometer, and a field lens. The second beam combiner is used to spatially combine the main processing laser and the preheating laser so that the two beams are output strictly coaxially. The field lens is used to maintain the focusing state of the two coaxial laser beams. The size of the preheating spot on the working surface is the same as or larger than the processing area.

[0011] In a further embodiment of the present invention, the temperature control monitoring optical path module includes a temperature measuring device and a signal processing unit. The temperature measuring device is an infrared thermometer or a thermal imager. The optical path of the temperature control monitoring optical path module is coaxially set with the laser optical path through a beam combiner to realize real-time non-contact monitoring of the temperature field around the preheating area and the molten pool. The signal processing unit is used to process the temperature signal collected by the temperature measuring device and transmit it to the intelligent control system.

[0012] In a further embodiment of the present invention, the intelligent control system is configured to execute a dynamic temperature closed-loop control strategy. This strategy includes receiving a real-time temperature signal transmitted by the temperature monitoring optical path module, comparing the detected temperature with a preset ideal preheating temperature range, automatically adjusting the output power of the preheating laser in real time through a PID control algorithm, and ensuring that the preheating area is maintained at the optimal temperature during the printing process. At the same time, the intelligent control system is also used to coordinate the switching of the main processing laser and the preheating laser, as well as the generation and execution of the scanning path.

[0013] A coaxial laser heating and dynamic temperature control galvanometer scanning laser processing method, using a coaxial laser heating and dynamic temperature control galvanometer scanning laser processing system, includes the following steps: Step 1: Path planning. Based on the 3D model slice data, plan the scanning path of the main processing laser. Step 2: Parameter setting, setting the initial process parameters for the main processing laser and the preheating laser, as well as the target temperature range for preheating; Step 3: Start preheating. Before the main processing laser scans the target area, the intelligent control system turns on the preheating laser in advance. The preheating laser is reflected by the reflector group, combined by the beam combiner, shaped by the beam shaping mirror group, and focused by the focusing mirror, forming a uniform preheating spot on the working surface to preheat the powder processing area. Step 4: Temperature control closed loop established. The temperature control monitoring optical path module starts working, detecting the temperature of the preheating area in real time and transmitting the temperature signal to the intelligent control system. The intelligent control system dynamically adjusts the output power of the preheating laser according to the temperature signal, so that the temperature of the preheating area can quickly reach and stabilize within the target temperature range. Step 5: Synchronous processing. After the temperature of the preheating area stabilizes, the intelligent control system turns on the main processing laser. The main processing laser and the preheating laser are combined by a beam combiner and output coaxially. The main processing spot formed by the main processing laser scans and melts in the uniformly preheated area. The preheating laser can be turned on simultaneously during the processing to ensure a uniform temperature field. Step Six: Repeat Steps Three through Five layer by layer until the entire part is printed.

[0014] In a further embodiment of the present invention, the preheating spot in step three is a flat-topped spot with uniform energy distribution, and the size of the preheating spot is adapted to the scanning range of the galvanometer.

[0015] In a further embodiment of the present invention, the temperature control monitoring optical path module in step four collects the temperature data of the preheating area in real time, processes it through the signal processing unit, and transmits it to the intelligent control system. The intelligent control system adjusts the power of the preheating laser according to the difference between the preset temperature threshold and the actual detected temperature.

[0016] In a further embodiment of the present invention, the main processing laser and the preheating laser in step five are strictly coaxial, and the main processing spot is scanned and processed within the area covered by the preheating spot to ensure that the preheating area and the processing area completely overlap.

[0017] In a further embodiment of the present invention, during the processing, the intelligent control system finely adjusts the output power of the preheating laser in real time through a PID control algorithm based on changes in scanning speed, ambient temperature, and part geometry to maintain a constant temperature in the preheating area.

[0018] The beneficial effects of this invention are: 1. By incorporating a beam-shaping mirror group within the preheating optical path module, the preheating laser is shaped from a traditional Gaussian distribution into a flat-top beam with uniform energy. The shaping method can be flexibly selected based on requirements, employing microlens homogenization, integrating mirror homogenization, or other schemes, ensuring a significant reduction in the uniformity error of the preheating beam's energy distribution. Simultaneously, the size of the preheating beam on the working surface is adapted to or slightly larger than the processing area, forming a fully covered, dead-angle-free, uniform preheating temperature field. This completely solves the problem of uneven temperature field in traditional overall preheating, fundamentally reducing the temperature gradient during material phase transformation and laying a core foundation for suppressing residual stress and process defects.

[0019] 2. A temperature control monitoring optical path module is set up, with an infrared thermometer or thermal imager coaxially positioned with the laser optical path to achieve real-time, non-contact monitoring of the temperature field around the preheating area and the molten pool. The intelligent control system constructs a dynamic temperature closed-loop control strategy based on a PID control algorithm. It can receive temperature signals in real time and compare them with the preset ideal temperature range, automatically adjusting the output power of the preheating laser to keep the temperature fluctuation range in the preheating area extremely small. Even with changes in scanning speed, ambient temperature fluctuations, or changes in part geometry, it can still maintain a constant temperature, effectively avoiding quality fluctuations caused by temperature drift in traditional processes, and significantly improving process stability and the repeatability of part forming quality.

[0020] 3. By using a beam combiner, the main processing laser and the preheating laser are spatially coaxially combined, ensuring that the two beams are strictly coaxially output. The coaxiality error can be controlled to an extremely low level, making the preheating area and the processing area completely overlap without relative positional deviation. This design is particularly suitable for complex trajectory scanning and thin-walled structure processing, avoiding the problems of local overheating or underheating caused by positional deviations in traditional non-coaxial preheating. It ensures that every processing area is in an optimal preheating state, significantly improving the forming quality and dimensional accuracy of complex-shaped parts.

[0021] 4. By combining a uniform preheating temperature field, dynamic and precise temperature control, and coaxial synchronous design, this invention can minimize the temperature gradient during the material phase transformation process, effectively suppress the generation and accumulation of residual stress, and significantly reduce the risk of warping and cracking of parts. Simultaneously, a stable temperature field ensures the stability of the molten pool, reduces defects such as powder splashing and spheroidization, and significantly improves the density and microstructure uniformity of the formed parts. Practical application verification shows that high-temperature alloy parts processed using this invention exhibit lower residual stress than those processed using traditional methods, with no hot cracks generated. Tensile strength, fatigue life, and other mechanical properties are significantly improved, meeting the stringent performance requirements of core components in high-end equipment.

[0022] 5. By integrating the preheating optical path, temperature control optical path, and main processing optical path into a single design, the need for a separate preheating furnace or large heating device is eliminated, significantly simplifying the equipment structure, reducing system complexity and failure rate, and saving equipment space. Furthermore, this invention provides precise preheating only to the printing area, rather than overall heating, resulting in a fast preheating response and eliminating lengthy heating times, thus significantly improving processing efficiency. In summary, this invention improves processing quality while maintaining economic efficiency and practicality, possessing extremely high industrial application value. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the optical path of the present invention; Figure 2 This is a schematic diagram of the scanning process performed on the light-emitting path. Detailed Implementation

[0024] The technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art in this application are within the scope of protection of this application.

[0025] In the description of this application, it should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. For ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following drawings denote similar items; therefore, once an item is defined in one drawing, it need not be further discussed in subsequent drawings.

[0026] It should be noted that the terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and not to describe a specific order or sequence. It should be understood that such use of data can be interchanged where appropriate so that embodiments of this application can be implemented in orders other than those illustrated or described herein, and the objects distinguished by "first," "second," etc., are generally of the same class and are not limited in number; for example, a first object can be one or more. Furthermore, in the specification and claims, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0027] It should be noted that in the description of this application, the directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" indicate the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as limiting the scope of protection of this application. The directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0028] It should be noted that, in this application, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element. Furthermore, it should be noted that the scope of the methods and apparatuses in the embodiments of this application is not limited to performing functions in the order shown or discussed, but may also include performing functions substantially simultaneously or in the reverse order, depending on the functions involved. For example, the described methods may be performed in a different order than described, and various steps may be added, omitted, or combined. Additionally, features described with reference to certain examples may be combined in other examples.

[0029] This embodiment provides a coaxial laser heating and dynamic temperature control galvanometer scanning laser processing system for intelligent welding via laser heating. The system comprises five core components: a main processing laser module, a preheating optical path module, a coaxial beam combining and scanning module, a temperature control monitoring optical path module, and an intelligent control system. Each module has a clearly defined function and works closely together to form a complete laser processing control system. The main processing laser module, as the core power source for material melting, outputs a high-energy-density main processing laser. This laser must have sufficient power to rapidly melt the printing material. Whether it is metal powder or non-metallic substrate, the energy input from the main processing laser can achieve a solid-to-liquid phase transition, laying the foundation for subsequent molten pool solidification. The performance of this module directly determines the efficiency of material melting and the initial stability of the molten pool, which is a key prerequisite for ensuring the density of the formed parts.

[0030] The preheating optical path module plays a crucial role in providing a uniform preheating environment for the processing area. Its core function is to generate a preheating spot with uniform energy distribution and a size that can be flexibly adjusted according to processing requirements, and then precisely guide this spot to the processing area through a specific optical path design. Compared to traditional overall preheating methods, this module can achieve targeted preheating of the processing area, avoiding energy waste while significantly improving preheating efficiency. It also reduces the temperature difference between the processing area and the surrounding environment from the source, creating favorable conditions for suppressing residual stress.

[0031] The coaxial beam combining and scanning module is a key structure for achieving simultaneous preheating and processing. Its main functions are, on the one hand, to precisely combine the main processing laser and the preheating laser in space, ensuring that the two laser beams are strictly coaxially output and eliminating the problem of misalignment between the preheating and processing areas caused by optical path deviation; on the other hand, to drive the coaxial laser beam to move along a preset path through the scanning mechanism, thereby realizing continuous processing of different areas of the part. The design of this module directly ensures the matching degree between the preheating effect and the processing process, and is especially suitable for processing complex-shaped parts, effectively avoiding process defects caused by insufficient or excessive preheating in local areas.

[0032] The temperature control monitoring optical path module acts as the system's "real-time sensing center." Its function is to continuously and non-contactly monitor the temperature field around the preheating area and the molten pool, capturing temperature change data in real time and providing accurate data for subsequent temperature control. In traditional processing, the lack of real-time temperature feedback often leads to preheating temperatures that are difficult to match processing requirements. This module, however, can monitor temperature dynamics in real time, promptly detect abnormal temperature fluctuations, and provide data support to ensure process stability.

[0033] The intelligent control system, acting as the "brain" of the entire system, establishes signal interaction with the main processing laser module, preheating optical path module, coaxial beam combining and scanning module, and temperature control monitoring optical path module through electrical connections. On the one hand, it enables the coordinated work of each module, coordinating key actions such as laser switching timing and scanning path execution; on the other hand, it achieves dynamic temperature closed-loop control, adjusting preheating parameters in real time based on temperature signals fed back by the temperature control monitoring module, ensuring that the temperature in the preheating area remains within the optimal range throughout the processing. The intelligent design of this control system significantly improves the automation level and stability of the process, reducing the impact of human error on processing quality.

[0034] In this embodiment, the preheating optical path module includes a preheating laser, a mirror assembly, a beam combiner 1, a beam shaping mirror assembly 2, and a focusing mirror 3. These components work together in a specific optical path sequence to transmit, shape, and focus the preheated laser. Specifically, the mirror assembly consists of a first mirror 4 and a second mirror 5. Its function is to flexibly adjust the transmission direction of the preheated laser through optical path reflection, changing the laser path according to the overall system layout requirements to ensure the laser accurately reaches subsequent optical components. This design makes the arrangement of the preheating optical path more flexible and adaptable to processing equipment of different sizes and structures.

[0035] The beam shaping mirror group 2 is the core component for achieving uniformity of the preheating spot. Its function is to shape the traditional Gaussian distribution laser output from the preheating laser into a flat-top spot with uniform energy distribution on the processing plane. Gaussian distribution laser has the defect of high energy in the center and low energy at the edge, which easily leads to uneven temperature in the preheating area. The flat-top spot can ensure that all positions in the processing area receive the same preheating energy, completely solving the problem of overheating in the center and insufficient energy at the edge in traditional preheating, and fundamentally improving the uniformity of the preheating temperature field.

[0036] The specific beam shaping method can be flexibly selected according to the characteristics of the processing material, the size of the processing area, etc., including any one of the following: microlens homogenization method, integrating mirror method, homogenizing rod method, and homogenizing fiber method. Although the principles of different shaping methods are different, they can all achieve uniform processing of laser energy. For example, the microlens homogenization method divides the laser into multiple sub-beams through a microlens array, and then achieves uniform energy distribution by superposition; the integrating mirror method uses the integration effect to redistribute the laser energy to ensure uniform energy of the output spot.

[0037] The laser output from the preheating laser is transmitted sequentially according to the optical path sequence of "reflector group → beam combiner 1 → beam shaping mirror group 2 → focusing mirror 3". First, the laser's direction is adjusted by the reflector group before entering beam combiner 1, where it is coaxially combined with the temperature control monitoring optical path. Then, it enters beam shaping mirror group 2 for energy homogenization. Finally, the laser is focused by focusing mirror 3, resulting in a precisely sized and uniformly energy-bearing preheating spot on the working surface. This spot is then guided to the coaxial beam combining and scanning module, preparing it for subsequent beam combining with the main processing laser. This optical path design not only ensures the transmission efficiency and spot quality of the preheating laser but also achieves synergy with the temperature control monitoring optical path, providing an optical path foundation for real-time temperature monitoring. Simultaneously, the uniform preheating spot effectively reduces the temperature gradient, lowering the risk of part warping and cracking, and improving part forming quality.

[0038] In this embodiment, the coaxial beam combining and scanning module includes a beam combining mirror 6, a galvanometer mirror 7, a galvanometer mirror 8, and a field mirror 9. Each component has a clear function, working together to achieve coaxial beam combining and scanning of the main processing laser and the preheating laser. Among them, the beam combining mirror 6 is the key component for achieving coaxiality of the two laser beams. Its function is to perform spatial beam combining of the main processing laser and the preheating laser. Through specific optical design, the two laser beams with different wavelengths and energies are transmitted on the same optical axis, ensuring that the two laser beams are strictly coaxially output. This avoids misalignment between the preheating area and the processing area due to optical axis deviation. This design ensures that any position scanned by the main processing laser is within the coverage of the preheating spot, achieving precise synchronization of preheating and processing. It is especially suitable for complex trajectory scanning and thin-walled structure processing, effectively avoiding thermal cracks caused by untimely preheating in local areas.

[0039] The dual-galvanometer structure, consisting of galvanometer 7 and galvanometer 8, is the core driving component for laser scanning. The two galvanometers rotate in the X and Y axes respectively. By precisely controlling the swing angle of the galvanometers, the coaxial laser beam is driven to move on the processing plane along the preset scanning path, realizing continuous processing of various areas of the part. The high response speed and high precision control of the galvanometers can meet the fine processing requirements of complex-shaped parts, ensure the accuracy and stability of the scanning path, and improve the dimensional accuracy of the parts.

[0040] As a key component of laser focusing, the field lens 9 functions to maintain the focused state of the main processing laser and the preheating laser on the processing surface, ensuring that both laser beams form precisely sized spots on the working surface, avoiding insufficient energy density or excessive concentration due to focusing deviation. Simultaneously, the field lens 9 also ensures that the size of the preheating spot on the processing surface is consistent with or larger than the processing area. Consistency with the processing area ensures accurate utilization of preheating energy, avoiding energy waste; a slightly larger size creates a "temperature field envelopment" effect, preventing a sudden temperature drop at the edges of the processing area due to excessive heat loss, further reducing the temperature gradient. This design not only improves the effectiveness of preheating but also ensures the stability of the molten pool, reduces process defects such as powder splashing and spheroidization, and improves part density and surface quality.

[0041] In this embodiment, the temperature control monitoring optical path module includes a temperature measuring device and a signal processing unit. This module is the "sensing and signal processing core" for realizing dynamic temperature control, providing accurate temperature data support for the intelligent control system. Specifically, the temperature measuring device is either an infrared thermometer or a thermal imager. Both devices offer the advantage of non-contact temperature measurement, enabling real-time temperature monitoring without interfering with the processing or contacting the high-temperature processing area. This avoids measurement errors caused by equipment wear and temperature conduction delays in traditional contact temperature measurement. Infrared thermometers are suitable for single-point or small-area temperature monitoring, offering fast response and high accuracy. Thermal imagers can acquire temperature field distribution images of the preheating area and the surrounding molten pool, enabling large-scale, multi-point temperature monitoring. A suitable temperature measuring device can be selected based on processing requirements to ensure comprehensive and accurate temperature monitoring.

[0042] The optical path of the temperature control monitoring optical path module is coaxially set with the laser optical path through beam combiner 1. This design enables the temperature measuring device to receive infrared radiation signals from the processing area along the opposite direction of the laser optical path, ensuring that the temperature measuring area completely overlaps with the preheating and processing areas. This avoids temperature monitoring deviations caused by optical path offset, enabling real-time and accurate monitoring of the temperature field around the preheating area and the molten pool. Whether it is the temperature of the area during the preheating stage or the temperature changes around the molten pool during processing, it can be captured in real time, providing comprehensive temperature data for dynamic temperature control.

[0043] The signal processing unit processes the raw temperature signal acquired by the temperature measuring device. Since the raw temperature signal may contain noise interference and signal fluctuations, the signal processing unit uses filtering, amplification, and digital conversion to transform the raw signal into accurate temperature data that the intelligent control system can recognize and analyze. This processed temperature data is then transmitted to the intelligent control system in real time, ensuring that the system can obtain accurate temperature information promptly and provide a reliable basis for subsequent temperature adjustment decisions. This module enables the system to have "real-time temperature sensing capabilities," avoiding overheating or underheating caused by the inability to monitor temperature in real time during traditional processing. This significantly improves process stability and provides data support for suppressing residual stress and reducing process defects.

[0044] In this embodiment, the intelligent control system is configured to execute a dynamic temperature closed-loop control strategy. This strategy is the core mechanism for ensuring temperature stability during processing. Through a closed-loop logic of "sensing-comparison-adjustment-feedback," it achieves precise control of the preheating temperature. Specifically, the execution process of the dynamic temperature closed-loop control strategy consists of four key steps: The first step is temperature signal reception. The intelligent control system receives processed temperature signals transmitted from the temperature monitoring optical path module in real time. These signals contain real-time temperature data of the preheating area and the surrounding molten pool, which is the basis for temperature adjustment. The second step is temperature comparison and analysis. The control system compares the real-time detected temperature with a preset ideal preheating temperature range. The ideal preheating temperature range is the optimal temperature range determined in advance based on factors such as the characteristics of the processed material, the structure of the part, and the processing technology. By comparing, it can quickly determine whether the current temperature is within a reasonable range and whether temperature adjustment is needed. The third step is automatic power adjustment. When the detected temperature deviates from the ideal range, the control system calculates the temperature deviation value through a PID control algorithm and adjusts the output power of the preheating laser in real time and automatically based on the deviation value. If the temperature is lower than the ideal range, the power is increased; if the temperature is higher than the ideal range, the power is decreased. The PID control algorithm has the advantages of fast response speed, high adjustment accuracy, and good stability, which can effectively avoid overshoot and oscillation problems in the temperature adjustment process and ensure that the temperature quickly returns to the ideal range. The fourth step is to maintain temperature stability. Through continuous signal reception, comparison, and power adjustment, it is ensured that the preheating area is always maintained at the optimal temperature throughout the printing process, avoiding temperature fluctuations caused by factors such as changes in ambient temperature and scanning speed adjustments.

[0045] Meanwhile, the intelligent control system also coordinates the working sequence and actions of each module. Specifically, this includes coordinating the switching sequence of the main processing laser and the preheating laser. For example, the preheating laser is turned on before processing, and the main processing laser is turned on only after the temperature stabilizes, avoiding excessive temperature gradients caused by the main processing laser directly acting on the cold material. Furthermore, the control system is responsible for generating and executing the scanning path. It generates a precise scanning path based on the 3D model slice data and drives galvanometers 7 and 8 to move along the path, ensuring the processing proceeds in an orderly manner according to design requirements. This control system design not only achieves intelligent and precise temperature control but also ensures the coordination and stability of the entire processing process, significantly improving the automation level of the process, reducing human intervention, and minimizing processing defects caused by human error. It also provides flexible parameter adjustment space for processing different materials and structural parts, enhancing the system's versatility and applicability.

[0046] This embodiment provides a specific example of the application of high-performance nickel-based superalloy processing. Nickel-based superalloys, due to their excellent high-temperature strength, oxidation resistance, and fatigue resistance, are widely used in core components such as turbine blades and combustion chambers of aerospace engines. However, these materials have low thermal conductivity and high susceptibility to hot cracking. Traditional laser processing easily generates hot cracks and high residual stress. This system effectively solves these problems through precise coaxial preheating and dynamic temperature control. The specific implementation process is as follows: I. System Configuration To address the material properties of nickel-based superalloys, the system modules were specifically configured: the main processing laser module uses a 500W 1064nm fiber laser, which has a high absorption rate on the surface of nickel-based superalloys, ensuring rapid melting and preventing molten spatter caused by excessive energy input; the preheating optical path module uses a 1000W 915nm semiconductor laser, which offers higher preheating efficiency for nickel-based superalloys, and its output power can be adjusted over a wide range to adapt to different preheating temperature requirements. A microlens array beam shaping mirror group 2 is connected to the front end of the preheating laser. This shaping method efficiently converts the Gaussian distribution of the 915nm laser into a flat-top beam, controlling the beam energy uniformity error within ±3%, meeting the stringent requirements of nickel-based superalloys for preheating temperature field uniformity; In the beam combining and scanning module, beam combiner 6 is a dual-color beam combiner with high transmission of 1064nm and high reflectivity of 915nm, ensuring efficient beam combining of two laser beams without energy loss. Galvanometer 7 and 8 are high-speed, high-precision galvanometers with a scanning accuracy of ±0.01mm. Field lens 9 is a flat f-θ lens with a focal length of 160mm, ensuring that both the preheating spot and the main processing spot maintain good focusing and dimensional stability within a 200mm×200mm processing area. The temperature control monitoring optical path module uses a high-speed infrared thermometer with a response speed of 1ms and a temperature measurement range covering 200℃-1200℃, which can accurately capture temperature changes during the preheating and processing of nickel-based high-temperature alloys. The signal processing unit has a built-in high-speed data acquisition card with a sampling frequency of 1kHz, ensuring real-time transmission and processing of temperature signals.

[0047] II. Processing Parameter Setting Based on the structural and performance requirements of the nickel-based superalloy parts to be processed (taking a segment of an aero-engine combustion chamber as an example, with dimensions of 150mm×100mm×30mm and a thin-walled structure accounting for 60%), the key process parameters are set as follows: the scanning speed of the main processing laser is 800mm / s, the spot diameter is 100μm, and the layer thickness is 30μm to ensure continuous melt channels and tight interlayer bonding; the initial output power of the preheating laser is set to 600W, and the target preheating temperature range is set to 400℃-420℃. This temperature can effectively reduce the hot cracking sensitivity of nickel-based superalloys without causing premature oxidation or softening of the powder, thus avoiding affecting the powder spreading quality; the scanning path adopts an "island scanning" strategy, dividing each layer into multiple 5mm×5mm islands. Each island is scanned bidirectionally, and the scanning directions between islands are staggered by 90° to reduce stress accumulation during the scanning process. At the same time, the preheating spot size is set to 200mm×200mm, which is perfectly matched with the processing area to ensure that the entire processing area is within a uniform preheating range.

[0048] III. Complete Processing Flow Path planning and parameter import: The 3D model of the combustion chamber segment is sliced ​​using professional slicing software with a slice thickness of 30μm to generate "island scan" path data. The path data and the set process parameters are then imported into the intelligent control system. The control system automatically verifies the rationality of the path and the matching of the parameters to ensure that there are no path overlaps or parameter conflicts.

[0049] Preheating and Temperature Field Establishment: The intelligent control system drives galvanometer 7 and galvanometer 8 to the processing start position, and then turns on the preheating laser. The 915nm laser is turned by mirror 4 and mirror 5 in sequence, enters beam combiner 1 and coaxially combines with the temperature control monitoring optical path, and then is shaped into a 200mm×200mm flat-top spot by microlens array beam shaping mirror group 2. Finally, it is focused by focusing mirror 3 and projected onto the surface of nickel-based high-temperature alloy powder bed to preheat the processing area.

[0050] Dynamic temperature control: The high-speed infrared thermometer is started synchronously to collect the surface temperature data of the powder bed in real time. The data is filtered and amplified by the signal processing unit and then transmitted to the intelligent control system. In the initial stage, the temperature is below 400℃. The control system gradually increases the power of the preheating laser through the PID algorithm. The power adjustment step is 5W. After each adjustment, the temperature is detected at an interval of 100ms until the temperature stabilizes at 410℃ (the midpoint of the target range). At this time, the PID control algorithm enters the fine-tuning mode, and the power adjustment step is reduced to 1W to ensure that the temperature fluctuation range is controlled within ±2℃.

[0051] Synchronous processing execution: After the temperature stabilizes for 10 seconds, the control system determines that the preheating effect has met the standard and turns on the main processing laser. The 1064nm main processing laser is coaxially combined with the 915nm preheating laser through beam combiner 26. Driven by the galvanometer, it moves along an "island scanning" path. The main processing spot scans and melts on the surface of the preheated powder bed, forming a continuous melt channel. During the processing, the preheating laser continues to work. The intelligent control system finely adjusts the preheating power in real time based on the temperature data fed back by the infrared thermometer. For example, when scanning to a thin-walled area, the temperature is likely to drop below 400℃ due to the rapid heat dissipation in the thin-walled area. The control system automatically increases the preheating power by 5-8W to maintain temperature stability. When scanning to a thick-walled area, the temperature is likely to rise above 420℃. The control system then reduces the preheating power by 3-5W to avoid excessive temperature and an excessively large melt pool.

[0052] Layer-by-layer cycle and quality assurance: After the current layer is processed, the powder bed descends 30μm, and the powder spreading device spreads a new layer. The "preheating-temperature control-processing" process is then repeated until all layers are processed. During the processing, the intelligent control system records the temperature change curve, laser power adjustment data, and scanning path execution status of each layer in real time, forming a complete process traceability document to facilitate subsequent quality analysis and parameter optimization.

[0053] IV. Verification of Processing Effect The nickel-based superalloy combustion chamber segments processed by this system have shown significant quality improvements after testing: X-ray flaw detection revealed an internal density of over 99.8%, with no hot cracks, pores, or other defects; residual stress testing (X-ray diffraction) reduced the surface residual stress value to below 80 MPa, a reduction of over 60% compared to traditional laser processing, fully meeting the residual stress requirements for aerospace components; mechanical property testing showed a room temperature tensile strength of 1250 MPa and a high-temperature (650℃) tensile strength of 980 MPa, representing an 8%-10% improvement over parts processed by traditional methods, and a fatigue life increase of over 15%, fully validating the superiority of this system in processing difficult-to-machine superalloy materials.

[0054] A coaxial laser heating and dynamic temperature control galvanometer scanning laser processing method is proposed. Based on the aforementioned coaxial laser heating and dynamic temperature control galvanometer scanning laser processing system, this method achieves high-quality, high-efficiency additive manufacturing of parts through six sequential steps. Each step is closely linked, forming a complete process chain from path planning to layer-by-layer processing. This effectively solves the problems of difficult temperature control, poor process stability, and low part quality in traditional processing methods. The specific steps are as follows: Step 1: Path planning; Before processing, the scanning path of the main processing laser is planned based on the 3D model slice data of the part to be processed. The 3D model slice data is obtained by dividing the 3D model of the part into several 2D slices according to a set layer thickness using professional slicing software. Each slice corresponds to one layer of the part's structure. The scanning path planning needs to comprehensively consider factors such as the part's geometry, material properties, and processing accuracy requirements. For example, for thin-walled structural parts, a path that can reduce stress concentration needs to be selected; for parts with high density requirements, the path overlap rate needs to be optimized to improve density; for example, in the processing of high-performance nickel-based high-temperature alloy combustion chamber segments, an "island scanning" path is adopted, dividing each layer into small islands and staggering the scanning direction to effectively reduce stress accumulation. A reasonable scanning path can not only improve processing efficiency but also reduce temperature fluctuations during processing, reduce the risk of residual stress, and ensure that all areas of the part can be processed uniformly, avoiding local overheating or insufficient processing caused by an unreasonable path, thus laying the foundation for subsequent precise processing.

[0055] Step 2: Parameter setting; After completing the path planning, the initial process parameters for the main processing laser and the preheating laser are set, and the target temperature range for preheating is determined. The process parameters for the main processing laser include laser power, scanning speed, and spot size. Different materials have different laser energy requirements. For example, high-temperature alloys require higher laser power to ensure sufficient melting, while non-metallic materials require lower power to avoid over-melting. For example, when processing nickel-based high-temperature alloys, the main processing laser power is set to 500W, the scanning speed to 800mm / s, and the spot diameter to 100μm to suit the material's melting requirements. The process parameters for the preheating laser include initial output power and spot size. The initial power needs to be initially set based on the target temperature range. For example, in processing nickel-based high-temperature alloys, the initial preheating laser power is 600W, and the spot size matches the processing area. The target preheating temperature range is determined based on the thermophysical properties of the material being processed. It must be ensured that this temperature effectively reduces the temperature gradient, suppressing residual stress and hot cracking, while preventing premature melting or oxidation of the material. For example, the target preheating temperature for high-strength steel is typically set at 300-500 degrees Celsius, for titanium alloys at 200-400 degrees Celsius, and for nickel-based superalloys at 400-420 degrees Celsius. Reasonable parameter settings are crucial for ensuring stable processing and meeting part quality standards, avoiding process defects caused by improper parameters.

[0056] Step 3: Start preheating; Before the main processing laser scans the target area, the intelligent control system activates the preheating laser according to a preset timing sequence, initiating the preheating process. The preheating laser is transmitted sequentially along a preset optical path. First, its direction is adjusted by reflection through a set of mirrors to ensure precise entry into beam combiner 1. Then, it is coaxially combined with the temperature control monitoring optical path through beam combiner 1, providing the optical path conditions for subsequent temperature monitoring. Subsequently, it enters beam shaping mirror group 2, completing the shaping from a Gaussian distribution to a flat-top spot, ensuring uniform distribution of preheating laser energy. For example, in the processing of nickel-based superalloys, the energy uniformity of the spot is shaped by a microlens array, with an error within ±3%. Finally, it is focused by focusing mirror 3, forming a uniform preheating spot on the working surface. This spot directly acts on the powder processing area to preheat the powder. Preheating in advance raises the temperature of the material in the processing area, reducing the temperature difference with the main processing laser, effectively reducing the temperature gradient, and lowering the risk of warping and cracking of parts. Especially for hot-crack sensitive materials such as nickel-based superalloys, preheating can significantly reduce the probability of hot cracking. Meanwhile, a uniform preheating spot can ensure that the temperature is consistent in all parts of the processing area, avoiding process defects caused by insufficient local preheating, and creating a stable temperature environment for the melting and forming of the subsequent main processing laser.

[0057] Step 4: Establish a closed-loop temperature control system; Simultaneously with the preheating start, the temperature control monitoring optical path module begins operation, and the temperature measuring device collects temperature data of the preheating area in real time. This data includes temperature information at various points in the preheating area, comprehensively reflecting the temperature field distribution. For example, in the processing of nickel-based superalloys, a high-speed infrared thermometer is used, with a 1ms response time ensuring the capture of minute temperature changes. The collected raw temperature data is transmitted to the signal processing unit, where it is processed through filtering, amplification, and digital conversion to become a precise and stable temperature signal, which is then transmitted to the intelligent control system in real time. For example, in the processing of nickel-based superalloys, the sampling frequency is 1kHz, ensuring that the temperature signal is transmitted without delay. After receiving the temperature signal, the intelligent control system compares the real-time detected temperature with the target temperature range set in step two to determine whether the current temperature is within the ideal range. If the detected temperature is below the target temperature range, the control system calculates the power adjustment amount using a PID control algorithm, increasing the output power of the preheating laser. If the detected temperature is above the target temperature range, the output power of the preheating laser is reduced. If the temperature is within the ideal range, the current power is maintained. For example, in the processing of nickel-based superalloys, the power is increased when the temperature is below 400℃ and decreased when it is above 420℃, with a fine-tuning step of 1W after stabilization. Through this real-time comparison and dynamic adjustment, the temperature in the preheating area quickly reaches and stabilizes within the target temperature range, establishing a complete closed-loop temperature control. This ensures the stability and accuracy of the preheating temperature, providing reliable temperature assurance for subsequent synchronous processing and avoiding processing quality problems caused by temperature fluctuations. Especially for the processing of nickel-based superalloys, temperature stability directly determines whether hot cracks will occur.

[0058] Step 5: Simultaneous processing; Once the temperature control monitoring optical path module reports that the preheating area temperature has stabilized within the target temperature range, the intelligent control system activates the main processing laser according to a preset timing sequence, entering the synchronous processing stage. After the main processing laser is output, it enters the beam combiner 6 together with the preheating laser processed by the preheating optical path. Under the action of the beam combiner 6, spatial beam combining is achieved, forming a strictly coaxial laser beam. For example, in the processing of nickel-based superalloys, a dual-color beam combiner ensures efficient beam combining of the 1064nm main laser and the 915nm preheating laser. Subsequently, driven by galvanometer 7 and galvanometer 8, it moves according to the scanning path planned in step one and is focused on the working surface by field mirror 9. At this time, the main processing spot formed by the main processing laser scans and melts in the uniformly preheated area. The stable temperature of the preheating area ensures that the material melts more fully and the molten pool is more stable when the main processing laser is applied, reducing process defects such as powder splashing and spheroidization of the melt channel. For example, in the processing of nickel-based superalloys, stable preheating improves the fluidity of the molten pool and significantly improves the quality of the melt channel formation. Simultaneously, the preheating laser can be turned on synchronously according to processing requirements to continuously provide preheating energy to the processing area, avoiding temperature drop caused by heat loss during processing, ensuring that the processing area is always maintained in a stable temperature environment, further improving the stability of the molten pool and the forming quality of the parts. Especially for the processing of thick-walled or large-sized parts, synchronous preheating can effectively avoid the problem of poor interlayer bonding caused by excessive temperature difference between layers. For example, in the processing of thick-walled areas of the combustion chamber of nickel-based high-temperature alloys, synchronous preheating controls the temperature difference between layers to within 50°C, and the interlayer bonding strength is improved by 12%.

[0059] Step Six: Loop through the layers; After completing the synchronous processing of the current layer, steps three through five are repeated according to the layer-by-layer forming principle of additive manufacturing to proceed to the next layer's processing flow. Specifically, the processing area of ​​the next layer is first preheated, and a temperature closed-loop control is established to ensure temperature stability. Then, the main processing laser is activated for scanning and melting. This cycle is repeated until all layers of the entire part are processed, resulting in a complete shaped part. During the layer-by-layer cycle, the intelligent control system will fine-tune the preheating and processing parameters in real time based on the geometry and scanning path differences of each layer. For example, when processing the thin-walled area of ​​the nickel-based high-temperature alloy combustion chamber, the preheating power is automatically increased by 5-8W due to rapid heat dissipation; when processing the thick-walled area, the preheating power is automatically reduced by 3-5W to ensure that the processing quality of each layer meets the design requirements. This layer-by-layer cyclic processing method can effectively control the temperature gradient between layers, avoid deformation or cracking of parts caused by stress accumulation between layers, and ensure tight bonding between layers, thereby improving the overall mechanical properties of the parts. Compared with traditional processing methods, this method can significantly improve the forming quality and dimensional accuracy of complex structural parts, meeting the stringent requirements of high-end equipment manufacturing for part quality. For example, in the processing of nickel-based high-temperature alloy combustion chamber segments, the layer-by-layer cyclic processing enables the part dimensional accuracy to reach ±0.1mm, which fully meets the tolerance requirements of aerospace components.

[0060] In this embodiment, the preheating spot mentioned in step three is a flat-topped spot, which has a uniform energy distribution. This ensures that all locations within the preheating area receive the same preheating energy, avoiding the uneven preheating problems caused by overheating at the center and insufficient heat at the edges of traditional Gaussian spots. Specifically, the energy distribution error of the flat-topped spot on the processing plane can be controlled within a small range, with minimal energy differences at each point. Whether at the center or the edge of the spot, it can provide a consistent preheating effect to the processing area. This uniform energy distribution allows the temperature of the material in the processing area to rise synchronously, effectively reducing the temperature gradient within the area and lowering the thermal stress caused by temperature differences. This, in turn, reduces the risk of warping and cracking of parts. For example, in the processing of nickel-based superalloys, the flat-topped spot controls the temperature difference at each point in the processing area within ±5℃, and the thermal stress is reduced by 40% compared to traditional Gaussian spots.

[0061] Meanwhile, the size of the preheating spot is matched with the scanning range of the galvanometer, which is the effective area for processing in the current layer. The matching of the spot size and the scanning range is manifested in two forms: First, the spot size is completely consistent with the scanning range, which can achieve precise utilization of preheating energy and avoid energy waste. This is suitable for processing small-sized, high-precision parts. For example, when processing small turbine blades of nickel-based high-temperature alloys, the spot size is perfectly matched with the 20mm×20mm scanning range, and the energy utilization rate is improved by 25%. Second, the spot size is slightly larger than the scanning range, forming a "temperature field buffer zone" to prevent the rapid loss of heat caused by heat exchange between the processing area edge and the non-processing area, and further maintain the temperature stability of the processing area. This is suitable for processing large-sized, thin-walled parts. For example, when processing a 1m×1m large nickel-based high-temperature alloy thin-walled component, the spot size is 50mm larger than the scanning range, and the temperature fluctuation in the edge area is controlled within ±3℃. Regardless of the adapter type, it can ensure that all processing areas scanned by the galvanometer are within the coverage of the uniform preheating spot, achieving precise matching between preheating and scanning processing. This provides a stable temperature environment for the subsequent melting and forming of the main laser, improving the forming quality and process stability of the parts.

[0062] In this embodiment, the temperature control monitoring optical path module described in step four collects temperature data of the preheating area in real time, enabling a comprehensive understanding of the temperature dynamics during the preheating process. The acquisition frequency can be set according to processing requirements to ensure timely capture of subtle temperature changes. Whether it is the rapid temperature rise stage in the initial preheating phase or the fluctuation stage after temperature stabilization, accurate temperature information can be obtained in real time. For example, when processing nickel-based superalloys, the acquisition frequency is set to 1kHz, so even a temperature fluctuation of 1℃ can be captured in time. The acquired temperature data is first transmitted to the signal processing unit. The signal processing unit performs multi-stage processing on the raw data, including filtering to remove noise signals caused by environmental interference, such as removing temperature signal fluctuations caused by airflow disturbances in the processing chamber; amplification to enhance the identifiability of weak temperature signals, such as amplifying the weak low-temperature signals in the initial preheating phase; and digital conversion to convert analog signals into digital signals that can be analyzed by the intelligent control system. The accuracy of the processed temperature data is greatly improved, and it can truly reflect the temperature state of the preheating area. For example, in the processing of nickel-based superalloys, the error of the processed temperature data is controlled within ±1℃.

[0063] The processed temperature data is transmitted to the intelligent control system in real time. The intelligent control system calculates the difference between the preset temperature threshold and the actual detected temperature. The preset temperature threshold is the upper and lower limits of the target temperature range set in step two. The difference calculation clarifies the degree of deviation between the current temperature and the ideal temperature. For example, when the actual detected temperature is lower than the lower threshold, the difference is negative, and the control system determines that the preheating power needs to be increased; when the actual detected temperature is higher than the upper threshold, the difference is positive, and the control system determines that the preheating power needs to be decreased; when the difference is within the allowable range, the temperature is determined to be stable, and the current power is maintained. For example, in the processing of nickel-based high-temperature alloys, the target temperature range is 400-420℃. When the temperature drops to 398℃, the difference is -2℃, and the control system increases the preheating power; when the temperature rises to 422℃, the difference is +2℃, and the control system decreases the preheating power. Based on the magnitude and sign of the difference, the intelligent control system calculates a precise power adjustment amount through a PID control algorithm, and adjusts the output power of the preheating laser in real time to ensure that the temperature in the preheating area can quickly return to and stabilize within the preset temperature threshold range. This process realizes dynamic closed-loop temperature control, avoiding the problem of temperature being easily affected by the environment and fluctuating greatly in traditional open-loop control. It significantly improves the stability and accuracy of the preheating temperature, providing a reliable guarantee for the quality of subsequent processing. Especially for heat-sensitive materials such as nickel-based high-temperature alloys, precise temperature control is the key to avoiding hot cracks.

[0064] In this embodiment, the main processing laser and the preheating laser described in step five are strictly coaxial. This coaxiality is achieved through the precise optical design and adjustment of the beam combiner 6. The optical axis deviation of the two laser beams can be controlled within a very small range (e.g., within ±0.05mm), ensuring that the scanning trajectory of the main processing laser corresponds completely to the coverage area of ​​the preheating laser, avoiding the problems of "processing area not preheated" or "preheated area not processed" caused by optical axis deviation. Strict coaxiality is the core prerequisite for achieving synchronous preheating and processing. It ensures that when the main processing laser acts on any position, that position has been fully preheated by the preheating laser, reducing the temperature gradient when the main processing laser acts and reducing the risk of thermal stress. For example, in the processing of thin-walled structures of nickel-based superalloys, coaxiality ensures that every thin-walled area scanned by the main processing laser spot has been preheated to 400-420℃, reducing the temperature gradient by 50% compared to non-coaxial design, and reducing the hot cracking rate from 30% in traditional processes to 0.

[0065] Simultaneously, the main processing spot scans within the area covered by the preheating spot. The coverage of the preheating spot is precisely designed to completely encompass the scanning trajectory of the main processing spot. Whether it's a straight-line scan, a curved scan, or a complex filling scan, the movement range of the main processing spot remains within the coverage of the preheating spot, achieving a collaborative mode of "preheating first, processing following closely." This design ensures that the preheating area and the processing area completely overlap, and every part of the processing area receives continuous and uniform preheating energy. This avoids instability in the molten pool caused by insufficient preheating at the edges of the processing area, reducing process defects such as powder splashing and spheroidization. For example, in the processing of nickel-based superalloys, when the preheating spot completely encompasses the main processing trajectory, the stability of the molten pool is improved, the amount of powder splashing is reduced by 60%, and the spheroidization rate drops from 15% to below 2%. At the same time, it ensures that the temperature of the processing area is always maintained within a reasonable range, improves the solidification quality of the molten pool and the interlayer bonding strength, and thus improves the density and mechanical properties of the parts. Especially for complex-shaped parts, this design can effectively solve the problem of difficult-to-control processing quality in local areas. For example, in the processing of complex internal cavities of nickel-based high-temperature alloy combustion chambers, the completely overlapping preheating and processing areas reduce the surface roughness of the internal cavity from Ra6.3μm to Ra1.6μm, and the density reaches 99.8%.

[0066] In this embodiment, during the processing, the intelligent control system has the ability to sense changes in processing conditions in real time and dynamically adjust preheating parameters. Specifically, it can fine-tune the output power of the preheating laser in real time through a PID control algorithm based on changes in scanning speed, ambient temperature, and part geometry, ensuring that the temperature of the preheating area remains constant. Changes in scanning speed directly affect the main processing laser energy received per unit area of ​​the processing area. When the scanning speed increases, the energy received per unit area decreases, and the heat input to the processing area decreases. At this time, the control system calculates the power compensation amount through the PID algorithm and appropriately increases the output power of the preheating laser to compensate for the reduction in heat input and maintain temperature stability. When the scanning speed decreases, the energy received per unit area increases, and the control system reduces the preheating power. For example, in the processing of nickel-based high-temperature alloys, when the scanning speed increases from 800 mm / s to 1000 mm / s, the control system automatically increases the preheating power by 30W to maintain a stable temperature of 410℃.

[0067] Changes in ambient temperature affect the rate of heat loss in the processing area. When the ambient temperature decreases, heat loss in the processing area accelerates, and the control system increases the preheating power to compensate for the lost heat. When the ambient temperature increases, heat loss slows down, and the control system reduces the preheating power. For example, when the temperature inside the processing chamber drops from 25°C to 15°C, the preheating power for processing nickel-based superalloys automatically increases by 25W to offset the temperature drop caused by ambient heat dissipation. Changes in the geometry of the part will alter the heat capacity and heat dissipation path of the processing area. For instance, when processing thin-walled areas, the material has a small heat capacity and dissipates heat quickly, so the control system appropriately increases the preheating power. When processing thick-walled areas, the material has a large heat capacity and dissipates heat slowly, so the control system reduces the preheating power. For example, when processing thin-walled areas (2mm thick) in the nickel-based superalloy combustion chamber, the preheating power is 50W higher than that of thick-walled areas (10mm thick) to ensure that the temperature in both types of areas remains stable within the target range.

[0068] Through real-time fine-tuning of the PID control algorithm, it can quickly respond to changes in various processing conditions, keeping the temperature fluctuation range of the preheating zone within a very small range (e.g., within ±2℃), ensuring a constant temperature throughout the processing, avoiding increased temperature gradients caused by changes in processing conditions, thereby suppressing residual stress generation, reducing defects such as warping and cracking of parts, improving process stability and part forming quality, and providing reliable temperature protection for part processing under different processing conditions, thus expanding the system's applicability. Especially in the processing of materials such as nickel-based superalloys that are sensitive to processing conditions, this dynamic adjustment capability is the key to ensuring consistent part quality.

Claims

1. A galvanometer scanning laser processing system with coaxial laser heating and dynamic temperature control, characterized in that, The system includes a main processing laser module, a preheating optical path module, a coaxial beam combining and scanning module, a temperature control monitoring optical path module, and an intelligent control system. The main processing laser module outputs a high-energy main processing laser to melt the printing material. The preheating optical path module generates a preheating spot with uniform energy and controllable size and guides it to the processing area. The coaxial beam combining and scanning module enables coaxial output and scanning of the main processing laser and the preheating laser. The temperature control monitoring optical path module monitors the temperature field around the preheating area and the molten pool in real time. The intelligent control system is electrically connected to the main processing laser module, the preheating optical path module, the coaxial beam combining and scanning module, and the temperature control monitoring optical path module to achieve dynamic temperature closed-loop control and collaborative operation of each module.

2. The coaxial laser heating and dynamic temperature control galvanometer scanning laser processing system according to claim 1, characterized in that, The preheating optical path module includes a preheating laser, a mirror group, a beam combiner, a beam shaping mirror group, and a focusing mirror. The mirror group includes a mirror and a mirror. The beam shaping mirror group is used to shape the energy distribution of the preheating laser into a flat-top spot. The beam shaping method includes any one of the following: microlens homogenization method, integrating mirror method, homogenizing rod method, and homogenizing fiber method. The laser output from the preheating laser is sequentially shaped by the mirror group, the beam combiner, the beam shaping mirror group, and focused by the focusing mirror before being guided to the coaxial beam combining and scanning module.

3. The coaxial laser heating and dynamic temperature control galvanometer scanning laser processing system according to claim 1, characterized in that, The coaxial beam combining and scanning module includes a beam combining mirror 2, a galvanometer mirror 1, a galvanometer mirror 2, and a field mirror. The beam combining mirror 2 is used to spatially combine the main processing laser and the preheating laser, so that the two beams are output strictly coaxially. The field mirror is used to maintain the focusing state of the two coaxial laser beams. The size of the preheating spot on the working surface is the same as or larger than the processing area.

4. The coaxial laser heating and dynamic temperature control galvanometer scanning laser processing system according to claim 1, characterized in that, The temperature control monitoring optical path module includes a temperature measuring device and a signal processing unit. The temperature measuring device is an infrared thermometer or a thermal imager. The optical path of the temperature control monitoring optical path module is coaxially set with the laser optical path through a beam combiner to realize real-time non-contact monitoring of the temperature field around the preheating area and the molten pool. The signal processing unit is used to process the temperature signal collected by the temperature measuring device and transmit it to the intelligent control system.

5. The coaxial laser heating and dynamic temperature control galvanometer scanning laser processing system according to claim 1, characterized in that, The intelligent control system is configured to execute a dynamic temperature closed-loop control strategy. This strategy includes receiving real-time temperature signals transmitted by the temperature monitoring optical path module, comparing the detected temperature with a preset ideal preheating temperature range, automatically adjusting the output power of the preheating laser in real time through a PID control algorithm, and ensuring that the preheating area is maintained at the optimal temperature during the printing process. The intelligent control system is also used to coordinate the switching of the main processing laser and the preheating laser, as well as the generation and execution of the scanning path.

6. A coaxial laser heating and dynamic temperature control galvanometer scanning laser processing method, using the coaxial laser heating and dynamic temperature control galvanometer scanning laser processing system described in claims 1-5, characterized in that, The coaxial laser heating and dynamic temperature control galvanometer scanning laser processing method includes the following steps: Step 1: Path planning. Based on the 3D model slice data, plan the scanning path of the main processing laser. Step 2: Parameter setting, setting the initial process parameters for the main processing laser and the preheating laser, as well as the target temperature range for preheating; Step 3: Start preheating. Before the main processing laser scans the target area, the intelligent control system turns on the preheating laser in advance. The preheating laser is reflected by the reflector group, combined by the beam combiner, shaped by the beam shaping mirror group, and focused by the focusing mirror, forming a uniform preheating spot on the working surface to preheat the powder processing area. Step 4: Temperature control closed loop established. The temperature control monitoring optical path module starts working, detecting the temperature of the preheating area in real time and transmitting the temperature signal to the intelligent control system. The intelligent control system dynamically adjusts the output power of the preheating laser according to the temperature signal, so that the temperature of the preheating area can quickly reach and stabilize within the target temperature range. Step 5: Synchronous processing. After the temperature of the preheating area stabilizes, the intelligent control system turns on the main processing laser. The main processing laser and the preheating laser are combined by a beam combiner and output coaxially. The main processing spot formed by the main processing laser scans and melts in the uniformly preheated area. The preheating laser can be turned on simultaneously during the processing to ensure a uniform temperature field. Step Six: Repeat Steps Three through Five layer by layer until the entire part is printed.

7. The coaxial laser heating and dynamic temperature control galvanometer scanning laser processing method according to claim 6, characterized in that, The preheating spot mentioned in step three is a flat-topped spot with uniform energy distribution, and the size of the preheating spot is adapted to the scanning range of the galvanometer.

8. The coaxial laser heating and dynamic temperature control galvanometer scanning laser processing method according to claim 6, characterized in that, The temperature control monitoring optical path module described in step four collects temperature data of the preheating area in real time, processes it through the signal processing unit, and then transmits it to the intelligent control system. The intelligent control system adjusts the power of the preheating laser according to the difference between the preset temperature threshold and the actual detected temperature.

9. The coaxial laser heating and dynamic temperature control galvanometer scanning laser processing method according to claim 6, characterized in that, In step five, the main processing laser and the preheating laser are strictly coaxial. The main processing spot scans and processes within the area covered by the preheating spot, ensuring that the preheating area and the processing area completely overlap.

10. The coaxial laser heating and dynamic temperature control galvanometer scanning laser processing method according to claim 6, characterized in that, During the processing, the intelligent control system adjusts the output power of the preheating laser in real time according to changes in scanning speed, ambient temperature, and part geometry, using a PID control algorithm to maintain a constant temperature in the preheating zone.

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