A local heating device and method for additive manufacturing of large scale parts

Abstract

The application belongs to the field of additive manufacturing, and discloses a local heating device and method for additive manufacturing of large-size parts, which comprises a hot air assembly arranged on both sides of a printing workbench, and a printing part is placed on the printing workbench; a plurality of air outlets are evenly arranged on the printing workbench in a matrix distribution, and the plurality of air outlets are arranged on both sides of the printing part; the hot air assembly comprises a hot air unit, a multi-degree-of-freedom adjusting unit and a plurality of hot air outlet hoses, one end of the plurality of hot air outlet hoses is communicated with the hot air unit, the other end of the hot air outlet hoses passes through the air outlets and is arranged on the surface of the printing workbench, and the multi-degree-of-freedom adjusting unit is installed on the hot air outlet hoses. The hot air outlet hoses directly act on both sides of the part through the air outlets, multi-point uniform heating is realized, the multi-degree-of-freedom adjusting unit is matched to realize synchronous cooperation of the heating action and the printing action, and full-range dead-angle-free heating is ensured.

Description

Technical Field

[0001] This invention belongs to the field of additive manufacturing, and in particular to a local heating device and method for printing large-size parts using additive manufacturing. Background Technology

[0002] Fused deposition modeling (FDM) is a widely used non-metallic polymer 3D printing technology. In this additive manufacturing technology, plastic polymers are heated and melted, and deposited and adhered to predetermined printing locations in liquid form through specific paths. The printed product is ultimately formed by the deposition and bonding of melt layer by layer.

[0003] During the printing process, the molten polymer of the current printing layer will shrink as it cools and solidifies on the upper surface of the lower polymer layer. However, due to the constraint of the hardened structure below, this shrinkage will cause shear force to form between layers, i.e. residual stress. This residual stress accumulates layer by layer and has great destructive power, which may cause the part to deform, curl up its edges, or even detach from the support.

[0004] Most existing methods for polymer 3D printing focus on improving surface quality. This is because most polymer prints are relatively small (maximum size less than 1m), making it easier to suppress deformation and reduce residual stress. By allowing margins before printing and then machining later, the required surface dimensions and precision can be achieved. However, larger parts exhibit greater residual stress. Conventional methods of allowing margins before printing and mechanical fixing can only eliminate a small portion of this residual stress and cannot meet the printing requirements.

[0005] Temperature control in the printing chamber to reduce temperature differences between layers is the most common method for reducing residual stress. Existing FDM 3D printing chamber temperature control devices use space heating to eliminate residual stress between printed layers. This requires completely sealing the equipment and using a heating mechanism. This approach can significantly reduce residual stress, thereby reducing deformation and improving print quality. However, when printing large parts (over 1m in size), the equipment also becomes larger. Completely sealing the equipment requires a larger sealed chamber and heat-resistant electrical components, increasing costs and failing to meet the low-cost, high-efficiency requirements of enterprises. Furthermore, larger parts require larger printing chambers, making overall chamber insulation more difficult, demanding higher quality components, and increasing energy consumption. Therefore, a method is needed that can both ensure the temperature of printed parts and reduce energy consumption. Summary of the Invention

[0006] The purpose of this invention is to provide a local heating device and method for printing large-size parts in additive manufacturing, which solves the problems of difficult heat preservation and high energy consumption in the prior art.

[0007] To achieve the above objectives, the present invention employs the following technical solution: A local heating device for printing large-size additive manufacturing parts includes hot air assemblies arranged on both sides of a printing worktable, on which the parts to be printed are placed. The printing worktable has several air outlets evenly distributed in a matrix. The air outlets are located on both sides of the printed parts. The hot air assembly includes a hot air unit, a multi-degree-of-freedom adjustment unit, and several hot air outlet hoses. One end of each hot air outlet hose is connected to the hot air unit, and the other end of the hot air outlet hose passes through the air outlet and is set on the surface of the printing worktable. The multi-degree-of-freedom adjustment unit is installed on the hot air outlet hose.

[0008] Furthermore, the material of the hot air outlet hose can withstand temperatures up to 300°C.

[0009] Furthermore, the printing workbench includes a cast iron platform, on which a connector fixing bracket is installed. The hot air outlet hose is connected to the connector installed on the connector fixing bracket. A transition plate is installed on the connector fixing bracket, and the air outlet point corresponds to the air outlet through hole opened on the transition plate.

[0010] Furthermore, the hot air outlet hose is connected to a four-way connector, which is connected to a three-way connector via a connecting pipe. Both the four-way connector and the three-way connector are connected to the air outlet.

[0011] Furthermore, several air outlets are provided on the air outlet base plate, which is mounted on the surface of the transition plate, and threaded plugs are provided on the air outlets.

[0012] Furthermore, the multi-degree-of-freedom adjustment unit includes a vertical movement structure and a horizontal movement structure. Both the vertical movement structure and the horizontal movement structure are mounted on a bracket. The bracket includes a support, a horizontal bracket, and a vertical bracket. The horizontal bracket and the vertical bracket are fixedly mounted on the support and are vertically fixedly connected.

[0013] Furthermore, a telescopic cylinder is fixedly installed on the horizontal support via a cylinder fixing bracket. The output end of the telescopic cylinder is connected to a connecting plate via screws, and a temperature measuring unit and an angle adjustment module are installed on the connecting plate.

[0014] Furthermore, the jaws of the angle adjustment module are mounted on the connecting plate via jaw fixing profiles. The jaws hold the hot air outlet hose and are connected to the output end of the rotary motor, which is mounted on the jaw fixing profiles.

[0015] Furthermore, a lifting motor and a linear guide are fixedly installed on the vertical support. The output end of the lifting motor is connected to a lead screw, and a lead screw nut is installed on the lead screw. A slider is slidably installed on the linear guide for moving and guiding.

[0016] A local heating method for additive manufacturing large-size parts printing using the aforementioned apparatus includes: Based on the size, shape, and heating area requirements of the printed parts, select the corresponding air outlet on the printing worktable and adjust the hot air outlet hose to the periphery of the printed parts; The hot air unit generates hot air, which is blown out through the hot air outlet hose at the selected air outlet point to provide real-time, uniform, and localized heating to both sides of the printed part. As the printed parts accumulate layer by layer and their contours change, the vertical and horizontal moving structures move synchronously with the vertical and horizontal displacements, causing the hot air outlet hose to change position with the printed parts, thus achieving localized heating without dead angles.

[0017] Compared with the prior art, the present invention has the following beneficial effects: This invention provides a local heating device for printing large-size parts in additive manufacturing. A hot air assembly is positioned on both sides of the printing table, which has a matrix of air outlets. These outlets are located on both sides of the printed part, achieving multi-point, symmetrical coverage of the heating area. The hot air diffuses evenly from both sides of the printed part, effectively avoiding temperature differences caused by excessive local heat dissipation, reducing internal stress caused by temperature gradients, and minimizing molding defects such as deformation and cracking. It is particularly suitable for meeting the overall temperature uniformity requirements when printing large-size parts. The hot air assembly includes a hot air unit and several hot air outlet hoses. One end of each hose is connected to the hot air unit, and the other end passes through an outlet on the surface of the printing table. The outlet positions can be flexibly selected according to the size and shape of the printed part, avoiding hot air waste. Meanwhile, the hot air outlet hose is connected to an up-and-down moving structure and a back-and-forth moving structure, allowing for flexible adjustment of the hose's position. This adapts to parts of varying widths and lengths, and can handle complex changes in part contours during printing, maintaining an effective heating distance from the part blank. This ensures the heating area precisely covers the area to be formed, preventing localized heating failures caused by changes in part shape and guaranteeing stable heating of large parts from bottom to top and from edge to center. The invention employs a matrix-distributed air outlet design, allowing flexible selection of outlet positions based on part size and heating requirements. Combined with the high-temperature resistant hot air outlet hose, the hose directly applies heat to both sides of the part through the outlet points, achieving uniform heating at multiple points and preventing localized overheating or underheating. The multi-degree-of-freedom adjustment unit integrates up-and-down, back-and-forth, and angle adjustment functions, enabling synchronized heating and printing actions. It can adjust the air outlet position in real time according to changes in printing height and part contour differences, adapting to the complex printing needs of large parts and ensuring heating without dead zones throughout the process. This overcomes the limitations of traditional fixed air outlet structures, significantly improving versatility. In addition, the overall structure does not occupy the core space of the printing area, will not interfere with core components such as the print head, will not affect printing efficiency, and ensures the smoothness of the production process.

[0018] Furthermore, a multi-point temperature measuring unit is added to the connecting plate, which moves synchronously with the hot air outlet hose. This allows for precise feedback of the heating temperature and real-time adjustment of hot air parameters and airflow status, effectively reducing temperature gradients and stress accumulation during the part printing process and minimizing molding defects such as deformation and cracking.

[0019] Furthermore, the printing worktable adopts a rigid structure design of cast iron platform + transition plate + connecting parts fixed bracket to ensure the stability of the air outlet base plate, avoid deformation during mechanism movement and hot air delivery, ensure the stability of the matrix air outlet position, and ensure that the air outlet direction and distance of the hot air outlet hose are precisely controllable, thereby ensuring uniform coverage of the heating area and improving the accuracy of heating position and temperature control.

[0020] Furthermore, the hot air outlet hose and clamps can be freely combined to adapt to the printing needs of different sized printed parts, making it highly versatile and easy to operate.

[0021] Furthermore, the matrix-style air outlet substrate provides a variety of air outlet options for printed parts of different sizes and shapes. With the help of threaded plugs to seal unused air outlets, the heating area can be precisely focused, avoiding energy waste caused by the indiscriminate diffusion of hot air.

[0022] Furthermore, the 300℃ resistant hot air outlet hose can stably withstand the delivery of high-temperature hot air, preventing hot air leakage due to high-temperature aging, deformation, or damage of the hose, ensuring that the hot air temperature is not significantly lost during delivery, and guaranteeing that the local heating temperature meets the standard.

[0023] Furthermore, by combining four-way connectors, connecting pipes, and three-way connectors, an efficient distribution pipeline can be constructed, which can evenly distribute the hot air generated by the hot air unit to multiple air outlets, avoiding the problem of uneven air volume distribution caused by a single pipeline, ensuring that the hot air volume and wind speed of each activated air outlet are consistent, and improving heating uniformity.

[0024] Furthermore, the rotary motor drives the jaws to rotate, causing the hot air outlet hose to swing at multiple angles, which can adapt to the complex contours of the printed parts. The air outlet angle is adjusted for areas such as the edges and corners of the parts and grooves that are prone to forming heating dead angles, ensuring heating without dead angles and further improving heating uniformity.

[0025] Furthermore, the lifting motor drives the lead screw transmission, and the lead screw nut cooperates with the slider to guide the linear guide rail, achieving high-precision positioning for up and down movement. This can accurately follow the height changes of the printed parts, ensuring that the hot air outlet hose always maintains the optimal heating distance and avoiding a decrease in heating effect due to height adjustment errors.

[0026] This invention also provides a method for localized heating in the printing of large-size additive manufacturing parts. First, based on the size, shape, and heating area requirements of the printed part, a corresponding air outlet is selected on the printing table. The hot air outlet hose is adjusted to the periphery of the printed part. Then, the hot air unit generates hot air, which is blown out through the selected hot air outlet hose, providing real-time, uniform, and localized heating to both sides of the printed part. This precisely focuses the heating area on both sides of the printed part, shortening the hot air delivery distance, reducing heat loss, and improving hot air utilization efficiency, thus reducing energy consumption while ensuring heating effect. Finally, as the printed part accumulates layer by layer and its contour changes, the vertical and horizontal moving structures synchronously move the hot air outlet hose according to the changing position of the printed part, enabling real-time linkage between the heating and printing processes. This achieves localized heating without dead angles, solving the problem that traditional fixed heating methods cannot adapt to dynamic changes in parts, and ensuring stable heating throughout the entire printing process from the beginning to the end. This invention addresses the challenges of layer-by-layer printing and contour variations in large-sized parts. By employing vertical and horizontal moving structures to synchronously adjust the position of the hot air outlet hose, it actively adapts to the dynamic changes during printing, effectively reducing temperature gradients and ensuring consistent temperature across all areas of the part. This process eliminates stress buildup caused by untimely or uneven heating, reducing molding defects such as deformation, cracking, and delamination, and significantly improving the stability and consistency of part molding quality. Attached Figure Description

[0027] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a schematic diagram of the local heating device for printing large-size additive manufacturing parts according to the present invention.

[0029] Figure 2 This is a schematic diagram of the printing workbench structure of the present invention.

[0030] Figure 3 This is a schematic diagram of the multi-degree-of-freedom adjustment unit structure of the present invention.

[0031] The components are as follows: 1-Hot air unit, 2-Multi-degree-of-freedom adjustment unit, 3-Printing worktable, 4-Hot air outlet hose, 5-Printed parts, 2.1-Cast iron platform, 2.2-Telescopic cylinder, 2.3-Cylinder fixing bracket, 2.4-Lead screw nut, 2.5-Lead screw, 2.6-Lifting motor, 2.7-Linear guide rail, 2.8-Slider, 2.9-Claw fixing profile, 2.10-Claw, 2.11-Connecting plate, 2.12-Temperature measuring unit, 2.13-Rotary motor, 3.1-Threaded plug, 3.2-Air outlet base plate, 3.3-T-connector, 3.4-Connecting pipe, 3.5-Four-way connector, 3.6-Connector fixing bracket, 3.7-Transition plate, 3.8-Cast iron platform. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0033] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0034] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0035] In the description of the embodiments of the present invention, it should be noted that if terms such as "upper," "lower," "horizontal," or "inner" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of the invention is in use, they are only for the convenience of describing the present invention and simplifying the description, and 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 a limitation of the present invention. Furthermore, terms such as "first" and "second" are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0036] Furthermore, the use of the term "horizontal" does not imply that the component must be absolutely horizontal, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0037] In the description of the embodiments of the present invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the present invention according to the specific circumstances.

[0038] The present invention will now be described in further detail with reference to the accompanying drawings: See Figure 1 The present invention provides a local heating device for printing large-size parts in additive manufacturing, including a hot air assembly, a printing worktable 3 and a temperature measuring unit 2.12, wherein the components work together to achieve the local heating function.

[0039] The hot air assembly is symmetrically arranged on both sides of the printing worktable 3, including a hot air unit 1, a multi-degree-of-freedom adjustment unit 2, and a hot air outlet hose 4. The hot air unit 1 is the hot air supply source. It forms a branch pipeline through a four-way connector 3.5, a connecting pipe 3.4, and a three-way connector 3.3, ultimately connecting to the hot air outlet hose 4. The hot air outlet hose 4 is made of a high-temperature resistant material with a temperature resistance of 300℃, ensuring the safety and stability of high-temperature hot air delivery during the printing process.

[0040] like Figure 2 As shown, the printing worktable 3 serves as the foundation for part support and hot air output, including a cast iron platform 3.8, a connector fixing bracket 3.6, a transition plate 3.7, an air outlet base plate 3.2, and a threaded plug 3.1. The cast iron platform 3.8 provides rigid support. The connector fixing bracket 3.6 is fixedly installed on the cast iron platform 3.8, the transition plate 3.7 is installed above the connector fixing bracket 3.6, and the air outlet base plate 3.2 is fixed to the surface of the transition plate 3.7. This multi-layered fixing structure ensures overall rigidity and prevents deformation during hot air delivery and mechanism movement. The air outlet base plate 3.2 has several air outlets arranged in a matrix, each corresponding to an air outlet through-hole on the transition plate 3.7. Hot air outlet hoses 4 extend through the air outlets to the surface of the printing worktable 3. The threaded plug 3.1 is used to seal any unselected air outlets. The air outlet position can be flexibly selected according to the size of the printed part 5 and heating requirements, ensuring that hot air is concentrated and delivered to the target area to heat the printed part 5.

[0041] like Figure 3As shown, the multi-degree-of-freedom adjustment unit 2 is mounted on the bracket 2.1. The bracket 2.1 includes a support, a horizontal bracket and a vertical bracket. The horizontal bracket and the vertical bracket are vertically fixedly connected. All motion, connection and control units are integrated on the bracket 2.1. The bracket 2.1 is fixed in the part printing area according to the equipment stroke.

[0042] The multi-degree-of-freedom adjustment unit 2 includes an up-and-down moving structure and a back-and-forth moving structure. An angle adjustment module is provided on the back-and-forth moving structure to realize multi-dimensional position adjustment of the hot air outlet hose 4.

[0043] The vertically moving structure is mounted on a vertical support, on which a lifting motor 2.6 and a linear guide rail 2.7 are fixedly installed. The output end of the lifting motor 2.6 is connected to a lead screw 2.5, and a lead screw nut 2.4 is mounted on the lead screw 2.5. A slider 2.8 is slidably mounted on the linear guide rail 2.7. The lifting motor 2.6 drives the lead screw 2.5 to rotate, causing the lead screw nut 2.4 and the slider 2.8 to move up and down along the linear guide rail 2.7. The lead screw 2.5 drives the movement, while the linear guide rail 2.7 and the slider 2.8 guide the movement, thus achieving height adjustment of the hot air outlet hose 4.

[0044] The forward and backward moving structure is mounted on a horizontal support. A telescopic cylinder 2.2 is mounted on the horizontal support via a cylinder fixing bracket 2.3. The output end of the telescopic cylinder 2.2 is connected to a connecting plate 2.11 via screws. The telescopic cylinder 2.2 with the required stroke can be selected according to the equipment's stroke. The forward and backward movement of the telescopic cylinder 2.2 is achieved by controlling the opening and closing of compressed air via a solenoid valve, which in turn moves the connecting plate 2.11 and subsequent components forward and backward to adapt to the printing width and contour of the parts.

[0045] An angle adjustment module is mounted on a connecting plate 2.11. A jaw 2.10 is mounted on the connecting plate 2.11 via a jaw fixing profile 2.9. The jaw 2.10 can open and close freely, clamping the hot air outlet hose 4. The hot air outlet hose 4 and the jaw 2.10 can be freely combined and distributed at multiple points. Different sizes and quantities of hot air outlet hoses 4 can be selected according to the size of the printed part 5. A rotary motor 2.13 is mounted on the jaw fixing profile 2.9. The jaw 2.10 is connected to the output end of the rotary motor 2.13. The rotary motor 2.13 drives the jaw 2.10 to rotate, enabling multi-angle swinging of the hot air outlet hose 4 to ensure heating without dead angles.

[0046] Temperature measurement unit 2.12 is installed on connecting plate 2.11 and adopts a multi-point distribution design. It can accurately collect the real-time temperature of each heating area and feed the temperature data back to the control system to provide a basis for temperature adjustment. The temperature is adjusted in real time according to the temperature requirements of different areas of the printed part 5.

[0047] The present invention also provides a local heating method for a local heating device used in additive manufacturing of large-size parts, comprising the following steps: Preparation stage before printing: Place the part 5 to be printed in the preset appropriate position on the printing worktable 3; Based on the size, shape, and heating area requirements of the printed part 5, select the target air outlet in the matrix of air outlets on the air outlet substrate 3.2, and seal the unselected air outlets with threaded plugs 3.1 to prevent hot air leakage. With the help of the multi-degree-of-freedom adjustment unit, the hot air outlet hose 4 is adjusted to a range of 10cm around the printed part 5 to ensure accurate initial heating position.

[0048] Heating stage of printing process: Start the hot air unit 1. After the hot air is split through the four-way connector 3.5, the connecting pipe 3.4, and the three-way connector 3.3, it is blown out through the hot air outlet hose 4 at the selected air outlet point to heat both sides of the printed part 5 in real time and in a uniform localized manner. As the printed parts 5 are stacked layer by layer and the printing height increases, the up-and-down moving structure is activated: the lifting motor 2.6 drives the lead screw 2.5 to rotate, which drives the hot air outlet hose 4 to adjust the air outlet position synchronously, always maintaining an effective heating distance from the part blank, so as to achieve local heating of the part blank; According to the contour change of the printed part 5, the extension and retraction of the telescopic cylinder 2.2 is adjusted by the front and rear moving structure, which drives the hot air outlet hose 4 to move back and forth; at the same time, the rotary motor 2.13 is started to drive the jaw 2.10 to rotate, and adjust the air outlet angle of the hot air outlet hose 4 to achieve local heating without dead angles. Temperature measurement unit 2.12 collects temperature data of each heating zone in real time and feeds it back to the control system. The control system adjusts the output air volume / temperature of hot air unit 1 in real time according to the temperature requirements of different areas of printed part 5, or further adjusts the position and angle of hot air outlet hose 4 to form closed-loop temperature control and ensure uniform and stable heating temperature.

[0049] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A local heating device for printing large-size parts in additive manufacturing, characterized in that, Includes a hot air assembly, which is set on both sides of the printing worktable (3), and the printed part (5) is placed on the printing worktable (3); The printing worktable (3) is evenly provided with a matrix of air outlets, which are distributed on both sides of the printed part (5). The hot air assembly includes a hot air unit (1), a multi-degree-of-freedom adjustment unit (2), and a number of hot air outlet hoses (4). One end of the hot air outlet hoses (4) is connected to the hot air unit (1), and the other end of the hot air outlet hoses (4) passes through the air outlets and is set on the surface of the printing worktable (3). The multi-degree-of-freedom adjustment unit (2) is installed on the hot air outlet hoses (4).

2. The local heating device for printing large-size additive manufacturing parts according to claim 1, characterized in that, The material of the hot air outlet hose (4) can withstand a temperature of 300℃.

3. The local heating device for printing large-size additive manufacturing parts according to claim 1, characterized in that, The printing workbench (3) includes a cast iron platform (3.8), on which a connector fixing bracket (3.6) is installed. The hot air outlet hose (4) is connected to the connector installed on the connector fixing bracket (3.6). A transition plate (3.7) is installed on the connector fixing bracket (3.6), and the air outlet point corresponds to the air outlet through hole opened on the transition plate (3.7).

4. The local heating device for printing large-size additive manufacturing parts according to claim 1, characterized in that, The hot air outlet hose (4) is connected to a four-way connector (3.5), which is connected to a three-way connector (3.3) via a connecting pipe (3.4). Both the four-way connector (3.5) and the three-way connector (3.3) are connected to the air outlet.

5. The local heating device for printing large-size additive manufacturing parts according to claim 1, characterized in that, Several air outlets are provided on the air outlet base plate (3.2), which is mounted on the surface of the transition plate (3.7). Threaded plugs (3.1) are provided on the air outlets.

6. The local heating device for printing large-size additive manufacturing parts according to claim 1, characterized in that, The multi-degree-of-freedom adjustment unit includes a vertical moving structure and a horizontal moving structure. Both the vertical moving structure and the horizontal moving structure are installed on the bracket (2.1). The bracket (2.1) includes a support, a horizontal bracket and a vertical bracket. The horizontal bracket and the vertical bracket are fixedly installed on the support and are vertically fixedly connected.

7. The local heating device for printing large-size additive manufacturing parts according to claim 6, characterized in that, A telescopic cylinder (2.2) is fixedly installed on the horizontal support via a cylinder fixing bracket (2.3). The output end of the telescopic cylinder (2.2) is connected to a connecting plate (2.11) via screws. A temperature measuring unit (2.12) and an angle adjustment module are installed on the connecting plate (2.11).

8. The local heating device for printing large-size additive manufacturing parts according to claim 7, characterized in that, The jaw (2.10) of the angle adjustment module is mounted on the connecting plate (2.11) via the jaw fixing profile (2.9). The jaw (2.10) clamps the hot air outlet hose (4). The jaw (2.10) is connected to the output end of the rotary motor (2.13). The rotary motor (2.13) is mounted on the jaw fixing profile (2.9).

9. The local heating device for printing large-size additive manufacturing parts according to claim 6, characterized in that, A lifting motor (2.6) and a linear guide rail (2.7) are fixedly installed on the vertical support. The output end of the lifting motor (2.6) is connected to a lead screw (2.5). A lead screw nut (2.4) is installed on the lead screw (2.5). A slider (2.8) is slidably installed on the linear guide rail (2.7) for moving and guiding.

10. A method for local heating in additive manufacturing of large-size parts using the apparatus described in any one of claims 1 to 9, characterized in that, include: According to the size, shape and heating area requirements of the printed part (5), select the corresponding air outlet on the printing worktable (3) and adjust the hot air outlet hose (4) to the periphery of the printed part (5); The hot air unit (1) generates hot air, which is blown out through the hot air outlet hose (4) at the selected air outlet point to heat both sides of the printed parts in real time and uniformly in a localized manner. As the printed parts (5) are stacked layer by layer and their contours change, the up-and-down moving structure and the back-and-forth moving structure drive the hot air outlet hose (4) to change position with the printed parts (5) through up-and-down movement and back-and-forth displacement, so as to achieve local heating without dead angles.

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