A method for generating a segmented scan path for stress deformation control in laser melting deposition additive manufacturing based on a temperature-controlled substrate

Abstract

The application provides a method for generating a segmented scanning path for stress deformation of laser melting deposition additive manufacturing based on a temperature control substrate, comprising: based on a temperature control substrate device, layering, partitioning and determining a scanning direction, layering a part, and based on the temperature control substrate device, partitioning each layer into a plurality of large areas, generating a plurality of small areas in each large area, and determining a scanning direction of laser for each small area; in the additive manufacturing process, measuring the temperature of each large area according to a corresponding temperature measuring instrument and thermocouple; processing the first layer, taking a small area as a processing unit, starting from a starting small area, completing the processing of one small area, adjusting the temperature field distribution through heating and cooling of each area, and selecting the next small area according to the temperature field distribution until the processing of the first layer is completed; after the first layer is processed, the part is processed layer by layer until the processing of the entire part is completed. The application reasonably controls the temperature gradient and stress distribution in the forming process of the formed part, and improves the forming quality of the part.

Description

Technical Field

[0001] This application relates to the field of additive manufacturing technology, specifically to a method for generating segmented scanning paths for stress deformation in controlled laser melting deposition additive manufacturing based on a temperature-controlled substrate. Background Technology

[0002] Additive manufacturing technology, which uses lasers as an energy source, utilizes high-energy laser beams to directly melt and solidify metal powder, forming high-melting-point, complex-shaped, or heterogeneous functionally graded parts. The forming process involves accumulating metal powder layer by layer according to the part's geometry. Its unique characteristics in metal part processing have led to its rapid development. On one hand, the cyclical rapid heating and cooling, melting, solidification, and solid-state phase transitions in metal parts result in uneven expansion and contraction of the material in space and time, leading to complex thermal stress and deformation in both the formed part and the substrate, potentially causing cracking or large deformation. On the other hand, in metal additive manufacturing, the substrate temperature directly affects the spread and solidification of the molten pool in the formed part, necessitating interlayer temperature control. Traditional interlayer temperature control relies on natural cooling, which takes too long and reduces additive manufacturing efficiency.

[0003] Currently, many solutions have been proposed to address this problem. Among them, optimizing the scanning strategy and adopting an island scanning method is a commonly used approach. This method can effectively reduce the temperature gradient during part processing and plays an important role in balancing surface and internal thermal stress and reducing stress deformation. However, with the island scanning method, the partitioning strategy and area scanning sequence are randomly and automatically generated within the software before processing. It cannot perform intelligent area selection and adjustment based on the part's own temperature. It can only alleviate the problem of overcooling and overheating in small areas of the part to a certain extent, lacking control over the overall temperature of the part. Therefore, it is necessary to develop auxiliary means for temperature control of substrates and formed parts in additive manufacturing technology, improve the temperature field distribution during processing, smooth out drastic temperature gradient changes, and thus suppress residual stress and deformation of substrates and formed parts. To achieve efficient and accurate substrate temperature control, efficient and accurate active temperature control of substrates and formed parts is required. Traditional substrate temperature control methods are all based on simple preheating and cooling, which cannot flexibly control the substrate temperature. Alternatively, traditional resistance heating is used for substrate preheating, which has disadvantages such as large heat loss, harsh ambient temperature, and short service life. Or, it does not consider the time-dependent nature of heat transfer and cannot accurately control the substrate temperature.

[0004] A literature search of existing technologies revealed a Chinese patent with publication number CN107159889A, which proposes a method for temperature zone measurement and control of parts in laser additive manufacturing. This method measures the temperature of parts in different zones during laser additive manufacturing and controls the overall temperature of the parts by specifying the laser scanning area online. This can effectively reduce the surface temperature gradient and balance stress distribution, thereby reducing the degree of deformation and the possibility of cracking. However, this method cannot achieve efficient and accurate active temperature control of the substrate and parts based on the part's own temperature.

[0005] Therefore, there is an urgent need to propose a scanning path generation method that can control the stress deformation in laser melting deposition additive manufacturing. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the purpose of this application is to provide a segmented scanning path generation method for stress deformation in controlled laser melting deposition additive manufacturing based on a temperature-controlled substrate.

[0007] According to one aspect of this application, a method for generating segmented scanning paths for stress deformation in controlled laser melting deposition additive manufacturing based on a temperature-controlled substrate is provided, comprising: Step 1: Based on the layering, partitioning and scanning direction determination on the temperature control substrate device, the part to be formed is layered. Each layer is divided into several large areas based on the partitioning of the temperature control substrate device. Then, multiple small areas are generated in each large area, and the scanning direction of the laser in each small area is determined. Step 2: During the additive manufacturing process, the temperature of each region is measured using the temperature measuring instrument and thermocouple corresponding to each region; Step 3: Process the first layer, using small areas as processing units. Start from the initial small area, and after completing the processing of one small area, move on to the next small area until the processing of the first layer is completed. Before the previous small area is completed, send a control signal in advance to make the temperature measuring instrument start collecting the temperature of each major area and adjust the temperature field distribution. By heating and cooling each major area, adjust the temperature field distribution and reduce the severity of temperature gradient changes. The next small area is any unprocessed small area within the major area with the lowest temperature. Step 4: After processing the first layer, process layer by layer until the entire part is completed; when processing layer by layer, the starting small area of ​​each layer is any small area located in the area with the lowest temperature in that processing layer. Starting from the starting small area, after completing the processing of a small area, move on to the next small area until the processing of that layer is completed; the next small area is any unprocessed small area in the area with the lowest temperature.

[0008] Optionally, the temperature control substrate device includes a substrate, a temperature control plate, a temperature detection system, and a temperature control system. The substrate includes multiple partitions, and the temperature control plate is disposed below the substrate and includes multiple partitions. The temperature detection system is connected to the substrate and the temperature control plate respectively and is used to detect the temperature of the substrate and the temperature control plate. The temperature control system is connected to the temperature control plate and is used to regulate the temperature of the temperature control plate, thereby regulating the temperature of each partition of the substrate.

[0009] Optionally, each section of the temperature control board is provided with a hollow metal spiral coil.

[0010] Optionally, the temperature detection system includes an infrared thermal imager, a thermocouple, and a multi-channel temperature sensor. The infrared thermal imager is oriented towards the part to be formed and is used to monitor the temperature of the part to be formed during the additive manufacturing process. The thermocouple is disposed between the substrate and the temperature control plate and is used to collect the temperature of the substrate and the temperature control plate. The multi-channel temperature sensor is connected to the thermocouple and monitors the temperature of the substrate and the temperature control plate through the thermocouple disposed between the substrate and the temperature control plate.

[0011] Optionally, the temperature control system includes a control cabinet, a water chiller, and an AC power supply. One end of the water chiller is connected to the control cabinet and is used to provide cooling water. One end of the AC power supply is connected to the control cabinet and is used to provide AC power for electromagnetic heating. The infrared thermal imager and the multi-channel thermometer are both connected to the control cabinet. The other ends of the water chiller and the AC power supply are both connected to the temperature control board. Based on the heat transfer law and the temperature monitoring results of the temperature detection system, the control cabinet performs electromagnetic heating or cooling water cooling on different areas of the substrate, thereby achieving timely and accurate temperature control of different areas of the substrate and regulating the temperature distribution of the substrate.

[0012] Optionally, the temperature control system further includes a zone channel valve, through which the water chiller is connected to the control cabinet.

[0013] Optionally, the control cabinet controls the water chiller and AC power supply based on the temperature monitored by the infrared thermal imager and the multi-channel thermometer.

[0014] Optionally, during the additive manufacturing process, the processed small areas are shielded to ensure that no single area is reprocessed during the part manufacturing process.

[0015] This application provides a segmented scanning path generation method for stress deformation in controlled laser melting deposition additive manufacturing based on a temperature-controlled substrate. This method can effectively solve the problem of regional overheating caused by traditional partitioning methods in additive manufacturing. It can reasonably control the temperature gradient and stress distribution during the forming process of the formed part, reduce the possibility of deformation and cracking, and improve the forming quality of the part.

[0016] Other technical effects resulting from the additional features will be further illustrated in the corresponding embodiments. Attached Figure Description

[0017] Other features, objects, and advantages of this application will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 This is a flowchart of a segmented scanning path generation method in one embodiment of this application; Figure 2 This is a schematic diagram of the temperature control substrate in one embodiment of this application. Detailed Implementation

[0018] The present application will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present application, but do not limit the present application in any way. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the present application, and these all fall within the protection scope of the present application. Parts not described in detail in the following embodiments can be implemented using existing technology.

[0019] Additive manufacturing technology using lasers as an energy source utilizes a high-energy laser beam to directly melt and solidify metal powder, enabling the direct forming of high-melting-point, complex-shaped, or heterogeneous functionally graded parts. The forming process involves accumulating metal powder layer by layer according to the part's geometry, and its unique metal part processing characteristics have led to its rapid development. However, existing additive manufacturing technologies may cause cracking or large deformation of the formed part and substrate, or reduce additive manufacturing efficiency. Based on these problems, this application provides a segmented scanning path generation method for controlled laser melting deposition additive manufacturing stress deformation based on a temperature-controlled substrate, to solve the aforementioned issues.

[0020] Reference Figure 1 and Figure 2 As shown, this application provides a method for generating segmented scanning paths for stress deformation in controlled laser melting deposition additive manufacturing based on a temperature-controlled substrate. The steps include: Step 1): Based on the layering, partitioning and scanning direction determination on the temperature control substrate device, the part to be formed is layered. Each layer is divided into several large areas based on the partitioning of the temperature control substrate device. Then, multiple small areas are generated in each large area, and the scanning direction of the laser in each small area is determined. Step 2): During the additive manufacturing process, the temperature of each region is measured using the temperature measuring instrument and thermocouple corresponding to each region; Step 3): Process the first layer, using small areas as processing units. Start from the initial small area, and after completing the processing of one small area, move on to the next small area until the processing of the first layer is completed. Before the previous small area is completed, give a control signal in advance to make the temperature measuring instrument start collecting the temperature of each major area and adjust the temperature field distribution. Adjust the temperature field distribution by heating and cooling each major area to reduce the severity of temperature gradient changes. The next small area is any unprocessed small area within the major area with the lowest temperature. Step 4): After processing the first layer, process layer by layer until the entire part is completed; when processing layer by layer, the starting small area of ​​each layer is any small area located in the area with the lowest temperature in that processing layer. Starting from the starting small area, after completing the processing of a small area, move on to the next small area until the processing of that layer is completed; the next small area is any unprocessed small area in the area with the lowest temperature.

[0021] In some specific embodiments of this application, the area of ​​the small region does not exceed 10 cm². 2 .

[0022] In some specific embodiments of this application, the total response time of temperature detection feedback in the segmented scanning path generation method does not exceed 1 second, ensuring that the processing is completed continuously without interruption.

[0023] In some specific embodiments of this application, during the additive manufacturing process, the already processed small areas are shielded to ensure that no single area is reprocessed during the part manufacturing process.

[0024] Based on the above embodiments, in another embodiment of this application, the provided method for generating segmented scanning paths for stress deformation in controlled laser melting deposition additive manufacturing based on a temperature-controlled substrate is based on a temperature-controlled substrate device with a specific structure.

[0025] Specifically, the temperature-controlled substrate device used in this embodiment includes a temperature control board, a temperature detection system, and a temperature control system. The temperature control board is located beneath the substrate and includes multiple partitions, each containing a hollow metal spiral coil. The temperature detection system includes an infrared thermal imager, thermocouples, and a multi-channel thermometer. The temperature control system includes a control cabinet, a water chiller, an AC power supply, and partition channel valves. Based on heat transfer principles and temperature monitoring results, the control cabinet uses electromagnetic heating or cooling water to raise the temperature of different areas of the substrate partitions, enabling timely and accurate temperature control of different regions of the additive manufacturing substrate, thereby regulating the temperature distribution of the substrate.

[0026] Furthermore, the temperature control substrate device includes a substrate, a temperature control plate, a temperature detection system, and a temperature control system. The substrate includes multiple partitions, and the temperature control plate, located below the substrate, also includes multiple partitions. Each partition of the temperature control plate contains a hollow metal spiral coil. The temperature detection system is connected to both the substrate and the temperature control plate to detect their temperatures. The temperature control system is connected to the temperature control plate to regulate its temperature, thereby regulating the temperature of each partition on the substrate. The temperature control plate is placed on a workbench, and a heat insulation layer is provided between the temperature control plate and the workbench.

[0027] The temperature detection system includes an infrared thermal imager, thermocouples, and a multi-channel temperature sensor. The infrared thermal imager is directed towards the part to be formed to monitor its temperature during the additive manufacturing process. The thermocouples are positioned between the substrate and the temperature control plate to collect the temperatures of both. The multi-channel temperature sensor is connected to the thermocouples and monitors the temperatures of the substrate and the temperature control plate through the thermocouples positioned between them.

[0028] The temperature control system includes a control cabinet, a water chiller, and an AC power supply. The water chiller is connected to the control cabinet and provides cooling water. The AC power supply is also connected to the control cabinet and provides AC power for electromagnetic heating. An infrared thermal imager and a multi-channel thermometer are both connected to the control cabinet. The other end of the water chiller and the other end of the AC power supply are both connected to the temperature control board. Based on the heat transfer law and the temperature monitoring results of the temperature detection system, the control cabinet performs electromagnetic heating or cooling water cooling on different areas of the substrate, enabling timely and accurate temperature control of different areas of the substrate, thereby regulating the temperature distribution of the substrate.

[0029] The temperature control system also includes zone channel valves, through which the water chiller is connected to the control cabinet.

[0030] The control cabinet controls the water chiller and AC power supply based on the temperature monitored by the infrared thermal imager and multi-channel thermometer.

[0031] The method for generating segmented scanning paths for stress deformation in controlled laser melting deposition additive manufacturing based on a temperature-controlled substrate using a temperature-controlled substrate device specifically includes the following steps: Step 1): Based on the layering, partitioning and scanning direction determination on the temperature control substrate device, the part to be formed is layered. Each layer is divided into several large areas based on the partitioning of the temperature control substrate device. Then, multiple small areas are generated in each large area, and the scanning direction of the laser in each small area is determined. Step 2): During the additive manufacturing process, the temperature of each region is measured using the temperature measuring instrument and thermocouple corresponding to each region; Step 3): Process the first layer, taking small areas as processing units. Start from the initial small area, and after completing the processing of a small area, adjust the temperature field distribution by heating and cooling each area, and select the next small area according to the temperature field distribution until the processing of the first layer is completed. Step 4): After processing the first layer, process each layer until the entire part is completed. This application can effectively solve the problem of regional overheating caused by traditional zoning methods in additive manufacturing, and can reasonably control the temperature gradient and stress distribution during the forming process of the formed part, reduce the possibility of deformation and cracking, and improve the forming quality of the part.

[0032] The parts not explicitly described in the above embodiments can be implemented with reference to existing technologies.

[0033] In summary, this application can achieve timely and accurate temperature control in different regions of additive manufacturing, thereby regulating the temperature distribution of the temperature field and controlling the stress and deformation of the formed part.

[0034] In the description of the embodiments of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. They are only for the convenience of describing this application 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. Therefore, they should not be construed as limitations on this application.

[0035] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature.

[0036] In the description of the embodiments in this application, "multiple" means two or more, unless otherwise explicitly specified. In this application, unless otherwise explicitly specified and limited, the terms "installed," "connected," "linked," "fixed," etc., 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 this application according to the specific circumstances.

[0037] The terms "comprising" and "having," and any variations thereof, in the embodiments of this application are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not limited to the steps or units listed, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to such processes, methods, products, or devices.

[0038] The preferred features in the above embodiments can be used individually in any embodiment, or in any combination thereof, provided they do not conflict with each other. Furthermore, parts not described in detail in the embodiments can be implemented using existing technologies.

[0039] The foregoing has described some specific embodiments of this application. It should be understood that this application is not limited to the specific embodiments described above, and those skilled in the art can make various modifications or variations within the scope of the claims, which do not affect the substantive content of this application. The above-described preferred features can be used in any combination without conflict.

Claims

1. A method for generating segmented scanning paths for stress deformation in controlled laser melting deposition additive manufacturing based on a temperature-controlled substrate, characterized in that, include: Step 1: Based on the layering, partitioning and scanning direction determination on the temperature control substrate device, the part to be formed is layered. Each layer is divided into several large areas based on the partitioning of the temperature control substrate device. Then, multiple small areas are generated in each large area, and the scanning direction of the laser in each small area is determined. Step 2: During the additive manufacturing process, the temperature of each region is measured using the temperature measuring instrument and thermocouple corresponding to each region; Step 3: Process the first layer, using small areas as processing units. Start from the initial small area, and after completing the processing of one small area, move on to the next small area until the processing of the first layer is completed. Before the previous small area is completed, send a control signal in advance to make the temperature measuring instrument start collecting the temperature of each major area and adjust the temperature field distribution. By heating and cooling each major area, adjust the temperature field distribution and reduce the severity of temperature gradient changes. The next small area is any unprocessed small area within the major area with the lowest temperature. Step 4: After processing the first layer, process layer by layer until the entire part is completed; when processing layer by layer, the starting small area of ​​each layer is any small area located in the area with the lowest temperature in that processing layer. Starting from the starting small area, after completing the processing of a small area, move on to the next small area until the processing of that layer is completed; the next small area is any unprocessed small area in the area with the lowest temperature.

2. The method for generating segmented scanning paths for stress deformation in controlled laser melting deposition additive manufacturing based on a temperature-controlled substrate, as described in claim 1, is characterized in that... The temperature control substrate device includes a substrate, a temperature control board, a temperature detection system, and a temperature control system. The substrate includes multiple partitions, and the temperature control board is located below the substrate and includes multiple partitions. The temperature detection system is connected to the substrate and the temperature control board respectively and is used to detect the temperature of the substrate and the temperature control board. The temperature control system is connected to the temperature control board and is used to regulate the temperature of the temperature control board, thereby regulating the temperature of each partition of the substrate.

3. The method for generating segmented scanning paths for stress deformation in controlled laser melting deposition additive manufacturing based on a temperature-controlled substrate, as described in claim 2, is characterized in that... Each section of the temperature control board is equipped with a hollow metal spiral coil.

4. The method for generating segmented scanning paths for stress deformation in controlled laser melting deposition additive manufacturing based on a temperature-controlled substrate, as described in claim 2, is characterized in that... The temperature detection system includes an infrared thermal imager, a thermocouple, and a multi-channel temperature sensor. The infrared thermal imager is directed towards the part to be formed and is used to monitor the temperature of the part to be formed during the additive manufacturing process. The thermocouple is disposed between the substrate and the temperature control plate and is used to collect the temperature of the substrate and the temperature control plate. The multi-channel temperature sensor is connected to the thermocouple and monitors the temperature of the substrate and the temperature control plate through the thermocouple disposed between the substrate and the temperature control plate.

5. The method for generating segmented scanning paths for stress deformation in controlled laser melting deposition additive manufacturing based on a temperature-controlled substrate, as described in claim 4, is characterized in that... The temperature control system includes a control cabinet, a water chiller, and an AC power supply. One end of the water chiller is connected to the control cabinet and is used to provide cooling water. One end of the AC power supply is connected to the control cabinet and is used to provide AC power for electromagnetic heating. The infrared thermal imager and the multi-channel thermometer are both connected to the control cabinet. The other ends of the water chiller and the other end of the AC power supply are both connected to the temperature control board. Based on the heat transfer law and the temperature monitoring results of the temperature detection system, the control cabinet performs electromagnetic heating or cooling water cooling on different areas of the substrate, thereby achieving timely and accurate temperature control of different areas of the substrate and regulating the temperature distribution of the substrate.

6. The method for generating segmented scanning paths for stress deformation in controlled laser melting deposition additive manufacturing based on a temperature-controlled substrate, as described in claim 5, is characterized in that... The temperature control system also includes a zone channel valve, through which the water chiller is connected to the control cabinet.

7. The method for generating segmented scanning paths for stress deformation in controlled laser melting deposition additive manufacturing based on a temperature-controlled substrate, as described in claim 5, is characterized in that... The control cabinet controls the water chiller and AC power supply based on the temperature monitored by the infrared thermal imager and the multi-channel thermometer.

8. The method for generating segmented scanning paths for stress deformation in controlled laser melting deposition additive manufacturing based on a temperature-controlled substrate, as described in claim 1, is characterized in that... The area of ​​the small region does not exceed 10cm². 2 .

9. The method for generating segmented scanning paths for stress deformation in controlled laser melting deposition additive manufacturing based on a temperature-controlled substrate, as described in claim 1, is characterized in that... The total response time for temperature detection feedback in the segmented scanning path generation method does not exceed 1 second, ensuring uninterrupted and continuous processing.

10. The method for generating segmented scanning paths for stress deformation in controlled laser melting deposition additive manufacturing based on a temperature-controlled substrate, as described in claim 1, is characterized in that... In the additive manufacturing process, the processed small areas are shielded to ensure that no single area is reprocessed during the part manufacturing process.

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