Multi-zone temperature control device of powder bed for LPBF

Abstract

The invention discloses a multi-zone temperature control device of a powder bed for LPBF, and belongs to the technical field of additive manufacturing. According to the temperature control device, four non-contact infrared heaters are arranged on the upper portion of the inner wall of a printing forming bin, and a heating plate formed by splicing a plurality of electric heating blocks is adopted at the bottom of a printing platform for contact heating; multi-zone flexible heating is achieved, independent temperature control can be achieved according to different zone requirements of parts, and the problem that in the prior art, temperature uniformity and zone control are insufficient is solved. The device is provided with an infrared temperature sensor and a thermocouple sensor to monitor the temperature in real time, the heating power is rapidly and accurately adjusted in combination with a PID control algorithm, and the temperature control response speed and precision are improved. The control module is intelligent, strategies can be automatically adjusted according to real-time data, working condition changes are adapted, the intelligent and self-adaptive capacity of the system is improved, and the requirements for modern manufacturing of high-precision and complex parts and the like are met.

Description

Technical Field

[0001] The present invention relates to the technical field of additive manufacturing, and in particular to a multi-zone temperature control device for a powder bed for LPBF. Background Art

[0002] Laser powder bed fusion (LPBF) technology, as one of the key technologies in the field of additive manufacturing, plays an increasingly important role in modern industrial production. However, in its application process, the temperature uniformity and precise control of the powder bed are one of the key factors to ensure the quality of printed parts. The appropriate temperature can fully melt the powder material and achieve good interlayer bonding, thereby improving the density and mechanical properties of the parts. If the temperature is not uniform, it may cause defects such as pores and cracks inside the parts, seriously affecting the strength and reliability of the parts. Due to the rapid laser heating and cooling process, the temperature difference in different areas will induce thermal stress, causing the parts to deform or even crack. Especially for parts with complex shapes, thin walls or fine structures, the impact of thermal stress is more significant.

[0003] There are many problems with the existing LPBF temperature control technology, which makes it difficult to meet the increasing manufacturing needs. First, in terms of temperature uniformity, traditional equipment mostly uses a single heating method, such as relying solely on the bottom heating plate or laser heat, which cannot achieve uniform heating of all areas of the powder bed. This is particularly obvious when printing parts with complex shapes. Due to uneven heat distribution in different parts, the performance varies greatly, and there is a lack of effective zoning control methods. Different areas cannot be independently adjusted according to the actual shape and structure of the parts, making it difficult to meet the diverse temperature requirements of complex parts.

[0004] Secondly, during the LPBF process, laser scanning causes the temperature to change rapidly. Traditional temperature control systems respond slowly and are difficult to track and adjust the heating power in real time, causing the temperature to deviate from the set value and affect the molding quality. In terms of control accuracy, simple feedback control algorithms such as proportional control or proportional-integral control are difficult to accurately control the temperature within a small error range and cannot meet the process requirements of materials and parts with high temperature accuracy requirements.

[0005] Furthermore, traditional systems usually require manual setting of fixed temperature parameters based on experience, and cannot automatically adjust according to actual printing conditions. Faced with changes in material properties, ambient temperature fluctuations, or changes in equipment status, it is difficult to adaptively optimize the temperature control strategy, resulting in unstable printing quality. Summary of the invention

[0006] The main purpose of the present invention is to provide a multi-zone temperature control device for a powder bed for LPBF, which can effectively solve the problems mentioned in the background technology.

[0007] To achieve the above object, the technical solution adopted by the present invention is:

[0008] A multi-zone temperature control device for a powder bed for LPBF comprises a base and a printing mechanism shell installed on the surface of the base, wherein the surface of the base is provided with a powder storage bin, a printing molding bin and an overflow powder bin inside the printing mechanism shell, respectively, and a laser generator and a scraper are installed on the top of the printing mechanism shell, wherein the scraper reciprocates to scrape metal powder in the powder storage bin to the printing molding bin, and scrapes excess metal to the overflow powder bin for recovery, wherein four non-contact heating infrared heaters are arranged above the inner wall of the printing molding bin, wherein a lifting box is installed inside the printing molding bin, wherein a liftable printing platform is movably installed inside the lifting box, wherein the printing platform mainly comprises a platform plate and a heating plate, wherein the heating plate is assembled from a plurality of electric heating blocks and is arranged at the bottom of the platform plate to provide contact heating.

[0009] Preferably, a group of movable track grooves are provided on the inner wall of the printing mechanism housing, and the scraper is connected to a driving mechanism installed on the outer wall of the printing mechanism housing through the movable track grooves to realize reciprocating motion.

[0010] Preferably, an air supply port is installed on the inner wall of the printing mechanism housing at the position of the printing molding chamber, and the air supply port is connected to an external gas cylinder through a pipeline to supply protective gas to the printing area of ​​the printing molding chamber.

[0011] Preferably, the infrared heater is symmetrically installed on the four sides of the top of the lifting box, and the heating surfaces are all facing the printing platform, and an infrared temperature sensor is respectively installed on both sides of the surface of the infrared heater.

[0012] Preferably, a circular mounting groove is provided on the bottom surface of the platform plate, a connecting column is fixedly installed at the center position of the top surface of the mounting groove, and the heating plate is installed in the mounting groove and electrically connected to the connecting column.

[0013] Preferably, a control module is fixedly installed inside the connecting column, and a plurality of mounting grooves are evenly arranged on the surface of the connecting column at the upper position. A power socket is provided on the top of each mounting groove, and the power socket is electrically connected to the control module through wires. The infrared heater is also electrically controlled with the control module through wireless communication.

[0014] Preferably, the heating plate is a disc-shaped structure with an opening in the middle, and is composed of a plurality of fan-shaped electric heating blocks. A thermocouple sensor is embedded on the surface of the electric heating block, and a power plug matching the power socket is provided on the inner ring surface of the electric heating block, and a ceramic insulation layer is provided on both side surfaces of the electric heating block.

[0015] Preferably, a clamping ring of an integral structure is further provided at the bottom edge of the mounting groove.

[0016] Preferably, the multi-zone temperature control method of the device comprises the following steps:

[0017] S1. Temperature monitoring

[0018] S1.1 Sensor data collection

[0019] Infrared temperature sensors installed on both sides of the infrared heater surface monitor the temperature of the area above the platform plate in real time and transmit it to the control module; the thermocouple sensors embedded on the surface of each electric heating block work simultaneously to measure the temperature of their respective areas. The thermocouple sensors convert the temperature data into electrical signals and transmit them to the control module through the line connected between the powered plug and the powered socket.

[0020] S1.2 Data integration and preprocessing

[0021] After the control module receives the temperature data from the infrared temperature sensor and the thermocouple sensor, it integrates them. First, the data is synchronized in time to ensure that the data collected by different sensors correspond to each other on the time axis. Then, the data is initially filtered to remove abnormal data points caused by interference factors such as noise. For example, a mean filter or median filter algorithm is used to process multiple continuously collected data points to obtain a relatively stable and accurate temperature value.

[0022] S2. Temperature control target setting

[0023] S2.1 Determination of target temperature for each zone

[0024] Divide the platform plate into different areas according to the requirements of the printing task and the characteristics of the powder material. For example, areas with complex structures or temperature-sensitive areas can be divided separately for more refined temperature control. Set the corresponding target temperature for each area. Generally speaking, for areas that require higher molding quality and accuracy, the target temperature can be set relatively high, but within the melting point and tolerable temperature range of the powder material. For areas prone to thermal deformation, the target temperature needs to be appropriately lowered. These target temperature values ​​can be determined through preliminary experiments and process analysis and stored in the memory of the control module.

[0025] S2.2 Temperature control accuracy requirements

[0026] Different temperature control accuracy requirements are set for different areas and printing stages. For example, when printing key parts of parts, the temperature control accuracy can be required to be within the range of ±3°C; while in some relatively unimportant areas or the initial stage of printing, the temperature control accuracy requirement can be appropriately relaxed to ±8°C.

[0027] S3, heating control strategy

[0028] S3.1 Infrared heater control

[0029] Before printing begins, the control module starts the infrared heater for non-contact preheating according to the preset initial temperature value. By adjusting the power of the infrared heater, the temperature of the area above the platform plate rises quickly to close to the initial target temperature.

[0030] During the printing process, when the infrared temperature sensor detects that the temperature of a certain area is lower than the target temperature by a certain range, the control module increases the power of the corresponding infrared heater to increase the temperature of the area. Conversely, if the temperature is too high, the power is reduced.

[0031] The power regulation of infrared heaters can adopt proportional-integral-derivative (PID) control algorithm to adjust the power output in real time according to temperature deviation and rate of change to ensure that the temperature is stable within the target range.

[0032] S3.2 Electric heating block control

[0033] Each electric heating block is independently controlled by a control module. Based on the temperature data fed back by the thermocouple sensor and the target temperature of the area, the control module calculates the heating power required for each electric heating block.

[0034] For electric heating blocks with a temperature lower than the target temperature, increase their power output; for electric heating blocks with a temperature close to or higher than the target temperature, reduce or stop their heating. Similarly, the power control of the electric heating block can also use a PID algorithm to achieve precise temperature regulation.

[0035] During the printing process, the power of the electric heating blocks in different areas is dynamically adjusted according to the printing progress and temperature distribution of the parts. For example, when the laser scans a certain area, the electric heating block corresponding to the area can increase the power appropriately to compensate for the temperature drop caused by the laser absorbing heat.

[0036] S3.3 Heating coordinated control

[0037] The infrared heater and the electric heating block are controlled in coordination. In the preheating stage, the infrared heater is used to quickly increase the overall temperature; during the printing process, the infrared heater and the electric heating block cooperate with each other to maintain the temperature stability of each area of ​​the platform plate.

[0038] When the temperature fluctuates greatly or changes abnormally, the control module can adjust the power of the infrared heater and the electric heating block at the same time to quickly restore to the target temperature. For example, if a certain area is suddenly affected by external factors and the temperature drops sharply, the control module can immediately increase the power of the infrared heater and the electric heating block in the area to achieve rapid temperature rise.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] The present invention has made innovative designs to address these existing technical problems. By arranging four non-contact infrared heaters above the inner wall of the printing molding chamber and using a heating plate assembled from multiple electric heating blocks at the bottom of the printing platform for contact heating, flexible heating of multiple zones is achieved. This design can perform independent temperature control according to the requirements of different zones of the parts, effectively solving the problems of poor temperature uniformity and insufficient zoning control in traditional technologies.

[0041] In addition, the device is equipped with infrared temperature sensors and thermocouple sensors, which can accurately monitor temperature changes in real time. Combined with advanced PID control algorithms, it can achieve rapid and accurate adjustment of heating power, greatly improving the response speed and accuracy of temperature control. At the same time, the intelligent design of the control module enables it to automatically adjust the temperature control strategy according to real-time data, adapt to various working conditions, improve the intelligence and adaptability of the system, and better meet the requirements of modern manufacturing for high-precision, complex parts manufacturing, intelligence and efficient production of LPBF process. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 It is a schematic diagram of the structure of the printing device of the present invention;

[0043] Figure 2 This is a schematic diagram of the internal structure of the printing molding chamber of the present invention;

[0044] Figure 3 An exploded view of the internal structure of the printing molding chamber of the present invention;

[0045] Figure 4 It is a schematic diagram of the structure of the printing platform of the present invention;

[0046] Figure 5 It is a schematic diagram of the heating plate and the connecting column structure of the present invention;

[0047] Figure 6 It is a cross-sectional view of the platform plate structure of the present invention.

[0048] In the figure: 1. base; 2. printing mechanism shell; 3. laser generator; 4. powder storage bin; 5. printing molding bin; 6. overflow powder bin; 7. scraper; 8. movable track groove; 9. air outlet; 10. lifting box; 11. printing platform; 12. infrared heater; 13. platform plate; 14. heating plate; 15. mounting groove; 16. connecting column; 17. control module; 18. power socket; 19. mounting slide; 20. electric heating block; 21. power plug; 22. ceramic insulation layer; 23. clamping ring; 24. infrared temperature sensor. DETAILED DESCRIPTION

[0049] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further explained below in conjunction with specific implementation methods.

[0050] like Figure 1 As shown, a multi-zone temperature control device for a powder bed for LPBF is a part of the structure of the entire 3D metal printing device. The laser powder bed melting printing device includes a base 1 and a printing mechanism shell 2 installed on the surface of the base 1. The surface of the base 1 is provided with a powder storage bin 4, a printing molding bin 5 and an overflow powder bin 6 inside the printing mechanism shell 2. A laser generator 3 and a scraper 7 are installed on the top of the printing mechanism shell 2. The scraper 7 reciprocates to scrape the metal powder in the powder storage bin 4 to the printing molding bin 5, and scrapes the excess metal to the overflow powder bin 6 for recovery. A group of movable track grooves 8 are opened on the inner wall of the printing mechanism shell 2. The scraper 7 is connected to the driving mechanism installed on the outer wall of the printing mechanism shell 2 through the movable track grooves 8 to realize reciprocating motion. An air supply port 9 is installed on the inner wall of the printing mechanism shell 2 at the position of the printing molding bin 5. The air supply port 9 is connected to the gas cylinder through a pipeline and supplies protective gas to the printing area of ​​the printing molding bin 5.

[0051] like Figure 3 As shown, four non-contact heating infrared heaters 12 are provided above the inner wall of the printing molding chamber 5. The infrared heaters 12 are symmetrically installed on the four sides of the top of the lifting box 10, and the heating surfaces are all facing the printing platform 11. An infrared temperature sensor 24 is installed on both sides of the surface of the infrared heater 12. The infrared heater 12 is electrically controlled through wireless communication and the control module 17.

[0052] like Figure 2 , Figure 4-Figure 6As shown, a lifting box 10 is installed inside the printing molding chamber 5, and a liftable printing platform 11 is movably installed inside the lifting box 10. The printing platform 11 mainly includes a platform plate 13 and a heating plate 14. A circular mounting groove 15 is opened on the bottom surface of the platform plate 13, and a connecting column 16 is fixedly installed at the center position of the top surface of the mounting groove 15. The heating plate 14 is installed in the mounting groove 15 and is electrically connected to the connecting column 16. A control module 17 is fixedly installed inside the connecting column 16, and a plurality of mounting grooves 19 are evenly arranged at the upper position on the surface of the connecting column 16. A power socket 18 is arranged on the top of the mounting groove 19, and the power socket 18 is electrically connected to the control module 17 through wires. The heating plate 14 is a disc-shaped structure with a hole in the middle, and is composed of a plurality of fan-shaped electric heating blocks 20. A thermocouple sensor is embedded on the surface of the electric heating block 20, and a power plug 21 matching the power socket 18 is respectively arranged on the inner ring surface of the electric heating block 20, and a ceramic insulation layer 22 is arranged on both side surfaces of the electric heating block 20.

[0053] In actual application, the laser powder bed fusion printing device works normally, the air supply port 9 fills the protective gas into the closed printing mechanism shell 2, and the driving mechanism on the back of the printing mechanism shell 2 drives the scraper 7 to reciprocate in a straight line to scrape the metal powder in the powder storage bin 4 to the printing platform 11 in the printing molding bin 5. After the metal powder is printed with a certain thickness, the excess metal powder is further scraped into the overflow powder bin 6 for recycling, and then the laser generator 3 on the top of the printing mechanism shell 2 works to melt and print the metal powder on the surface of the printing platform 11.

[0054] Before the formal printing work begins, the initial parameters are set in the control module 17 using the control panel of the equipment according to the material properties and design requirements of the parts. The platform plate 13 is divided into multiple areas, and the thin-walled parts and the areas near the internal cavities of the printed products are set as critical areas, and the other parts are relatively non-critical areas. The target temperature of each area is determined through preliminary tests and process analysis. At the same time, the temperature control accuracy of key parts is set to ±3°C, and the temperature control accuracy of non-critical areas or the initial stage of printing is set to ±8°C.

[0055] After the device is turned on, the infrared temperature sensor 24 and the thermocouple sensor start working. The infrared temperature sensor 24 monitors the overall temperature distribution of the area above the platform plate 13 in real time, and transmits the data to the control module 17 at a frequency of 10 times per second. The thermocouple sensor accurately measures the temperature of the area where each electric heating block 20 is located, converts the temperature data into an electrical signal, and transmits it to the control module 17 at a frequency of 5 times per second through the line connected between the power plug 21 and the power jack 18.

[0056] After receiving the data from the two sensors, the control module 17 first performs time synchronization processing to ensure that the data corresponds on the time axis. Then, a mean filtering algorithm is used to process multiple continuously collected data points. For example, for each data collection of each sensor, the 10 most recent data points are averaged to obtain a relatively stable and accurate temperature value, and abnormal data points caused by factors such as equipment operation and environmental electromagnetic interference are removed.

[0057] According to the requirements of the printing task, the target temperature of each zone is determined according to the different structural characteristics of the parts. Since the thin-walled part dissipates heat quickly, a higher temperature is required to ensure that the powder is fully melted and to avoid defects such as cold shut, so its target temperature is set in a relatively high range. Since heat is easily accumulated in the area near the internal cavity during laser scanning, the target temperature is relatively low to prevent deformation or degradation of material properties caused by overheating. Through the device control panel connected to the control module 17, the target temperature setting of each area can be intuitively viewed and fine-tuned according to the actual situation.

[0058] During the printing process, the temperature control accuracy requirements are adjusted according to different printing stages. In the initial stage of printing, the powder is mainly leveled and preheated. At this time, the temperature control accuracy requirements for the entire platform plate 13 can be relaxed to ±8°C. When entering the printing of key parts of the parts, such as thin-walled parts and areas near internal cavities, the temperature control accuracy is increased to ±3°C to ensure the molding quality of these areas. The control module 17 will automatically switch the accuracy mode according to the preset program, and monitor in real time whether the temperature deviation is within the allowable range.

[0059] 1. Infrared heater control

[0060] Before printing begins, the control module 17 starts the infrared heater 12 for non-contact preheating according to the preset initial temperature value. Through wireless communication, the control module 17 adjusts the power of the infrared heater 12 so that the temperature of the area above the platform plate 13 rises rapidly. The PID control algorithm is used to adjust the power output in real time according to the temperature data fed back by the infrared temperature sensor 24 and the preset temperature rise curve. For example, when the temperature rises too slowly, the power is increased; when the temperature approaches the initial target temperature, the power is gradually reduced so that the temperature rises steadily to a temperature close to the initial target temperature, and the error is controlled within the set accuracy range, such as ±8°C.

[0061] During the printing process, when the infrared temperature sensor 24 detects that the temperature of a certain area is lower than the target temperature by a certain range, such as exceeding the deviation of ±3°C, the control module 17 immediately increases the power of the corresponding infrared heater 12 to increase the temperature of the area. On the contrary, if the temperature is too high, such as exceeding the target temperature by ±3°C, the power is reduced. The PID controller dynamically adjusts the power output according to the temperature deviation and the rate of change to ensure that the temperature is stable within the target range. For example, when it is detected that the temperature of a key area drops rapidly, the PID algorithm will quickly calculate the power value that needs to be increased and send instructions to the infrared heater 12 to increase the output power in a short time to compensate for the temperature loss.

[0062] 2. Electric heating block control

[0063] Each electric heating block 20 is independently controlled by the control module 17. During the printing process, the control module 17 uses a built-in algorithm to calculate the heating power required for each electric heating block 20 based on the temperature data fed back by the thermocouple sensor and the target temperature of the area. For electric heating blocks 20 with a temperature lower than the target temperature, their power output is increased; for electric heating blocks 20 with a temperature close to or higher than the target temperature, their heating is reduced or stopped. The PID algorithm is also used for precise power regulation.

[0064] When the laser scans a certain area, the electric heating block 20 corresponding to the area will increase the power appropriately according to the preset strategy to compensate for the temperature drop caused by the laser absorbing heat. For example, when the laser scans a thin-walled part, since the thin-walled part dissipates heat quickly and absorbs more laser energy, the control module 17 will promptly increase the power of the electric heating block 20 in the area to ensure that the temperature remains within the target range. At the same time, according to the printing progress and temperature distribution of the parts, the power of the electric heating blocks 20 in different areas is dynamically adjusted. For example, after completing one layer of printing, for the area to be printed on the next layer, the power of the electric heating block 20 is adjusted in advance to reach the appropriate preheating temperature.

[0065] 3. Heating coordinated control

[0066] In the preheating stage, the infrared heater 12 is mainly used to quickly increase the overall temperature. The infrared heater 12 operates at a higher power, so that the powder bed above the platform plate 13 quickly reaches a temperature close to the initial target temperature. At the same time, the electric heating block 20 also operates at a lower power to assist in maintaining temperature uniformity and reducing temperature gradients.

[0067] During the printing process, the infrared heater 12 and the electric heating block 20 cooperate with each other to maintain the temperature stability of each area of ​​the platform plate 13. When the temperature fluctuates greatly or changes abnormally, the control module 17 can adjust the power of the infrared heater 12 and the electric heating block 20 at the same time. For example, if a certain area is suddenly affected by external factors, such as a failure of the equipment cooling fan causing a local temperature increase, the control module 17 will immediately increase the power of the infrared heater 12 and the electric heating block 20 in the area, or reduce the heating power of adjacent areas at the same time, so as to quickly restore to the target temperature and ensure the temperature stability of the entire printing process.

[0068] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A multi-zone temperature control device for a powder bed for LPBF, comprising a base (1) and a printing mechanism housing (2) mounted on the surface of the base (1), wherein the surface of the base (1) is provided with a powder storage bin (4), a printing molding bin (5) and an overflow powder bin (6) located inside the printing mechanism housing (2), and a laser generator (3) and a scraper (7) are mounted on the top of the printing mechanism housing (2), wherein the scraper (7) reciprocates to scrape metal powder in the powder storage bin (4) to the printing molding bin (5), and scrapes excess metal to the overflow powder bin (6) for recovery, wherein: Four non-contact heating infrared heaters (12) are arranged above the inner wall of the printing molding chamber (5); a lifting box (10) is installed inside the printing molding chamber (5); a liftable printing platform (11) is movably installed inside the lifting box (10); the printing platform (11) mainly includes a platform plate (13) and a heating plate (14); the heating plate (14) is assembled from a plurality of electric heating blocks (20) and is arranged at the bottom of the platform plate (13) to provide contact heating.

2. A multi-zone temperature control device for a powder bed for LPBF according to claim 1, characterized in that: A group of movable track grooves (8) are provided on the inner wall of the printing mechanism housing (2), and the scraper (7) is connected to a driving mechanism installed on the outer wall of the printing mechanism housing (2) through the movable track grooves (8) to realize reciprocating motion.

3. The multi-zone temperature control device for a powder bed for LPBF according to claim 1, characterized in that: An air supply port (9) is installed on the inner wall of the printing mechanism housing (2) at a position located in the printing molding chamber (5); the air supply port (9) is connected to an external gas cylinder through a pipeline and supplies protective gas to the printing area of ​​the printing molding chamber (5).

4. The multi-zone temperature control device for a powder bed for LPBF according to claim 1, characterized in that: The infrared heater (12) is symmetrically mounted on the four sides of the top of the lifting box (10), and the heating surfaces are all facing the printing platform (11). An infrared temperature sensor (24) is respectively mounted on both sides of the surface of the infrared heater (12).

5. The multi-zone temperature control device for a powder bed for LPBF according to claim 4, characterized in that: The bottom surface of the platform plate (13) is provided with a circular installation groove (15), and a connecting column (16) is fixedly installed at the center position of the top surface of the installation groove (15). The heating plate (14) is installed in the installation groove (15) and is electrically connected to the connecting column (16).

6. The multi-zone temperature control device for a powder bed for LPBF according to claim 5, characterized in that: A control module (17) is fixedly installed inside the connecting column (16); a plurality of mounting grooves (19) are evenly arranged on the surface of the connecting column (16) at an upper position; a power supply socket (18) is provided at the top of each mounting groove (19); the power supply socket (18) is electrically connected to the control module (17) via an electric wire; and the infrared heater (12) is also electrically controlled by the control module (17) via wireless communication.

7. The multi-zone temperature control device for a powder bed for LPBF according to claim 6, characterized in that: The heating plate (14) is a disc-shaped structure with a hole in the middle, and is composed of a plurality of fan-shaped electric heating blocks (20). A thermocouple sensor is embedded on the surface of the electric heating block (20). An electric plug (21) matching the power socket (18) is provided on the inner ring surface of the electric heating block (20), and a ceramic insulation layer (22) is provided on both side surfaces of the electric heating block (20).

8. The multi-zone temperature control device for a powder bed for LPBF according to claim 7, characterized in that: A clamping ring (23) of an integral structure is also provided at the bottom edge of the installation groove (15).

9. A multi-zone temperature control device for a powder bed for LPBF according to any one of claims 1 to 8, characterized in that: The multi-zone temperature control method of the device comprises the following steps: S1. Temperature monitoring S1.1 Sensor data collection Infrared temperature sensors (24) installed on both sides of the surface of the infrared heater (12) are used to monitor the temperature of the area above the platform plate (13) in real time and transmit the temperature to the control module (17); thermocouple sensors embedded on the surface of each electric heating block (20) work simultaneously to measure the temperature of the respective area, and the thermocouple sensors convert the temperature data into electrical signals and transmit the electrical signals to the control module (17) through a line connected between the power plug (21) and the power socket (18); S1.2 Data integration and preprocessing After receiving the temperature data from the infrared temperature sensor (24) and the thermocouple sensor, the control module (17) integrates the data; first, the data is time synchronized to ensure that the data collected by different sensors correspond to each other on the time axis; then, the data is preliminarily filtered to remove abnormal data points; S2. Temperature control target setting S2.1 Determination of target temperature for each zone According to the requirements of the printing task and the characteristics of the powder material, the platform plate (13) is divided into different sector-shaped areas, and a corresponding target temperature is set for each area. These target temperature values ​​are determined through previous experiments and process analysis and stored in the memory of the control module (17); S2.2 Temperature control accuracy requirements Set different temperature control accuracy requirements for different areas and printing stages; S3, heating control strategy S3.1 Infrared heater control Before printing begins, the control module (17) starts the infrared heater (12) for non-contact preheating according to a preset initial temperature value, and adjusts the power of the infrared heater (12) so that the temperature of the area above the platform plate (13) rises quickly to a temperature close to the initial target temperature; During the printing process, when the infrared temperature sensor (24) detects that the temperature of a certain area is lower than the target temperature, the control module (17) increases the power of the corresponding infrared heater (12) to increase the temperature of the area; conversely, if the temperature is too high, the power is reduced; The power regulation of the infrared heater (12) adopts a proportional-integral-differential (PID) control algorithm to adjust the power output in real time according to the temperature deviation and the rate of change to ensure that the temperature is stable within the target range; S3.2 Electric heating block control Each electric heating block (20) is independently controlled by a control module (17), and the control module (17) calculates the heating power required by each electric heating block (20) based on the temperature data fed back by the thermocouple sensor and the target temperature of the area where it is located; For the electric heating block (20) whose temperature is lower than the target temperature, the power output thereof is increased; for the electric heating block (20) whose temperature is close to or higher than the target temperature, the heating thereof is reduced or stopped; During the printing process, the power of the electric heating blocks (20) in different areas is dynamically adjusted according to the printing progress and temperature distribution of the parts; S3.3 Heating coordinated control The infrared heater (12) and the electric heating block (20) are controlled in a coordinated manner. In the preheating stage, the infrared heater (12) is mainly used to quickly increase the overall temperature. In the printing process, the infrared heater (12) and the electric heating block (20) cooperate with each other to jointly maintain the temperature stability of each area of ​​the platform plate (13). When the temperature fluctuates greatly or changes abnormally, the control module (17) simultaneously adjusts the power of the infrared heater (12) and the electric heating block (20) to quickly restore to the target temperature.

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