A method and apparatus for dynamic control of multi-material additive manufacturing

Abstract

This invention belongs to the field of additive manufacturing technology and provides a dynamic control method and apparatus for multi-material additive manufacturing. The method includes reading the target material corresponding to the current printing task and determining whether the target material is the same type as the residual powder on the current substrate. When the determination result is different, the powder spreading component is controlled to collect the residual powder on the substrate surface during the outward reciprocating motion along the substrate surface, and to spread the target material on the substrate surface during the return motion. When the determination result is the same, the powder spreading component is controlled to spread the target material on the substrate surface during the outward and / or return reciprocating motion along the substrate surface. The advantage of this invention is that it decouples the powder spreading motion into an outward cleaning mode and a return powder spreading mode, and records the type of residual powder on the current substrate in real time, achieving precise replacement of different materials between layers.

Description

Technical Field

[0001] This invention relates to the field of additive manufacturing technology, and in particular to a dynamic control method and apparatus for multi-material additive manufacturing. Background Technology

[0002] Additive manufacturing technology has been widely applied in aerospace, medical, and other fields. Laser powder bed fusion (LPBF) is a mainstream technology for fabricating high-performance metal parts. With the increasing demand for functionally graded materials (FGMs) and multifunctional integrated parts, depositing multiple materials in the same manufacturing process has become a research hotspot. Existing multi-material LPBF equipment typically arranges multiple powder feeding devices above the substrate, achieving material switching through a cyclical step of "laying material A → laser sintering → removing unmelted material A → laying material B → laser sintering". However, existing technologies have the following limitations: 1. Hardware Damage Risk: In metal additive manufacturing, the formed object often develops micro-warping or surface burrs due to the accumulation of thermal stress. In the traditional process of removing residual material, the squeegee typically moves in close contact with the substrate and lacks the lubrication and buffering effect of the powder layer. At this time, hard squeegees (such as ceramic / high-speed steel squeegees) are very prone to rigid collisions with the protruding object, causing the squeegee to chip or even break, which not only damages expensive equipment but also causes the printing job to fail directly.

[0003] 2. Powder cross-contamination: Existing powder collection systems often lack intelligent identification and diversion mechanisms for the type of residual powder on the current substrate, resulting in different materials being drawn into the same container, causing expensive powder to be unable to be recycled.

[0004] 3. Low process efficiency: Traditional control logic strictly follows the printing order of slice layer index. When there are multiple non-contiguous material regions within a single layer, the equipment will perform multiple meaningless material change cycles.

[0005] 4. Poor material scalability: Existing designs are mostly limited to switching between dual hoppers (material A / B), lacking array-based powder supply and collaborative control schemes for N types (N≥3) of materials. Summary of the Invention

[0006] The present invention aims to solve the above problems and provide an additive manufacturing method and apparatus that can be compatible with any number of materials, has hardware anti-collision protection, and can maximize powder recovery rate.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A dynamic control method for multi-material additive manufacturing includes the following steps: Read the target material corresponding to the current printing task and determine whether the target material is the same as the type of residual powder on the current substrate; When the judgment result is different, the powder spreading component is controlled to collect the residual powder on the substrate surface during the outward reciprocating motion along the substrate surface, and to spread the target material on the substrate surface during the return stroke. When the judgment results are the same, determine whether the current printing task and the previous printing task are located on the same printing layer; if they are located on different printing layers, control the powder spreading component to spread the target material on the substrate surface during the outward and / or return strokes of the reciprocating motion along the substrate surface.

[0008] Furthermore, before starting all printing tasks for the current layer, the following steps are also included: Obtain the current residual powder type on the substrate surface and read all print job files for the current layer to form an execution queue; The tasks are grouped according to the properties of the target material corresponding to each print task file. When there is a task group with the same properties as the target material and the residual powder type, the task group with the same properties is moved to the first position in the execution queue.

[0009] Furthermore, the powder spreading assembly includes a powder suction nozzle; the powder suction nozzle is configured to pick up residual powder on the substrate surface or spread the target material onto the substrate surface when it reciprocates along the substrate surface.

[0010] Furthermore, the powder spreading assembly also includes a scraper, which is configured to move in a direction perpendicular to the direction of movement of the powder suction nozzle.

[0011] Furthermore, during the outward stroke of the powder suction nozzle, the scraper is configured to perform a lifting action so that its bottom surface is higher than the top surface of the currently formed solid layer and forms a clearance gap; and during the return stroke of the powder suction nozzle, the scraper is configured to perform a lowering action to spread the powder on the substrate surface.

[0012] Furthermore, the vertical height value of the clearance is configured to be greater than the estimated thermal deformation warpage of the current layer's formed entity.

[0013] The present invention also provides a dynamic control device for multi-material additive manufacturing, comprising: The powder supply assembly includes at least two powder dispensing cylinders, which store powder material corresponding to the printing task. The diversion and recycling component includes at least one recycling container, and the recycling container corresponds one-to-one with the powder material in the powder drop cylinder; A powder spreading assembly, which is connected to a powder discharge cylinder and a recycling container respectively, and reciprocates on the substrate surface; the powder spreading assembly is configured as follows: After determining that the type of powder remaining on the current substrate surface is different from the target material corresponding to the next printing task, the residual powder material on the substrate surface is collected into a recycling container during the outward reciprocating motion along the substrate surface, and the target material is extracted from the corresponding powder drop cylinder and laid on the substrate surface during the return stroke.

[0014] Furthermore, the powder spreading assembly includes a powder suction nozzle and a scraper; the powder suction nozzle is configured to pick up residual powder from the substrate surface when it reciprocates along the substrate surface; the scraper is configured to move in a direction perpendicular to the direction of movement of the powder suction nozzle.

[0015] Furthermore, the powder dispensing cylinders are arranged in an array, and each powder dispensing cylinder is independently controlled to open and close.

[0016] Furthermore, the diversion and recycling assembly includes a diversion valve, the front end of which is connected to the powder suction nozzle, and the rear end is connected to a recycling container that corresponds one-to-one with the material in the powder drop cylinder; when the powder suction nozzle sucks up the residual powder on the surface of the substrate, the residual powder flows into its corresponding recycling container through the switching of the diversion valve.

[0017] Compared with the prior art, the present invention has at least the following beneficial effects: (1) Status recognition and queue optimization: The system records the type of residual powder on the current substrate in real time and dynamically reorganizes the printing task queue of each layer accordingly, prioritizing the merging and execution of tasks with the same material, thereby minimizing the number of material changes; (2) Action decoupling and anti-collision protection: The powder spreading motion is decoupled into an outgoing cleaning mode and a return powder spreading mode. In the outgoing cleaning mode, the scraper is forcibly raised, which physically eliminates the risk of collision between the scraper and the object; (3) Establish a linkage mechanism between the powder suction pipeline and the state of residual powder to ensure that the suctioned powder is recycled into the correct independent container and achieve high-purity recovery. Attached Figure Description

[0018] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the accompanying drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0019] Figure 1 This is a schematic diagram of the overall structure of the multi-material additive manufacturing dynamic control device provided in this embodiment; Figure 2 This is a schematic diagram of the device provided in this embodiment performing an outgoing cleaning operation; Figure 3 This is a schematic diagram of the device provided in this embodiment performing the return powder spreading action; Figure 4 This is a schematic diagram of the steps of the multi-material additive manufacturing dynamic control method provided in this embodiment; Figure 5This is a flowchart of the dynamic control method for multi-material additive manufacturing provided in this embodiment.

[0020] In the figure, 1 is the substrate, 2 is the formed solid, 3 is the powder bed, 4 is the doctor blade, 5 is the powder suction nozzle, 6 is the powder drop cylinder, 6a is the first powder drop cylinder, 6b is the second powder drop cylinder, 6n is the nth powder drop cylinder, 7 is the laser, 8 is the galvanometer scanning system, 9 is the laser beam, 10 is the diversion valve, 11 is the recovery container, 11a is the first recovery container, and 11n is the nth recovery container. Detailed Implementation

[0021] The following are specific embodiments of the present invention, and the technical solutions of the present invention will be further described in conjunction with the accompanying drawings. However, the present invention is not limited to these embodiments.

[0022] like Figure 1 As shown, this embodiment provides a multi-material additive manufacturing dynamic control device, which includes a substrate 1 that carries the printing task and a pre-formed entity 2 located thereon. Figure 1 In the initial state shown, a complete powder bed 3 is covered on the substrate (as shown in the gray rectangular area in the figure), and its top surface height is basically flush with the top surface height of the formed entity 2, and the entity is wrapped in the powder bed.

[0023] The device is equipped with a laser scanning system located above the physical object, including a laser 7, a galvanometer scanning system 8, and a laser beam 9 emitted and controlled by the laser, for selective melting and sintering of the powder bed 3.

[0024] A multi-channel powder supply assembly is provided on one side above the substrate 1 (shown as the upper right in the figure). This assembly consists of multiple powder drop cylinders 6 arranged in an array. The figure schematically shows the first powder drop cylinder 6a, the second powder drop cylinder 6b, and the nth powder drop cylinder 6n, which are used to store different powder materials (such as the first material, the second material to the nth material), and each powder drop cylinder can be independently controlled to open and close.

[0025] The powder spreading assembly is positioned at its initial location. This assembly includes a scraper 4 that can move vertically and a powder suction nozzle 5 physically connected to and moving with it. The powder suction nozzle 5 is connected to a diversion valve 10 via a flexible conduit. The rear end of the diversion valve is connected to multiple recovery containers corresponding to the material in the powder discharge cylinder, shown in the diagram as the first recovery container 11a to the nth recovery container 11n. By switching the diversion valve within the diversion and recovery assembly, the waste powder sucked in through the powder suction nozzle can be guided to the corresponding recovery containers for classified recycling.

[0026] The powder spreading component is configured to: determine the type of powder remaining on the surface of the current substrate 1. Target material corresponding to the next printing task After the difference, during the outward reciprocating motion along the surface of substrate 1, the residual powder material on the surface of the printed substrate is collected into the recycling container, and during the return stroke, the target material is extracted from the corresponding powder drop cylinder and laid on the surface of substrate 1.

[0027] Specifically, such as Figure 2 As shown, during the outward cleaning action in the material switching process, the powder spreading component moves to the left. The powder suction nozzle 5 is in the active working state and is responsible for removing residual powder on the path of the substrate 1.

[0028] In front of the powder suction nozzle 5, the substrate 1 is still covered with old powder to be removed, and its height is flush with the already formed entity 2. Behind the powder suction nozzle, the old powder has been removed, exposing the clean surface of the substrate 1 or the already formed entity 2.

[0029] To prevent the scraper 4 from touching the formed object 2 when it is not lubricated with powder, the device drives the scraper 4 to perform a lifting action, so that its bottom surface is significantly higher than the top surface of the formed object 2, thereby creating a safe clearance gap between the scraper and the object. During this process, all powder-falling cylinders (first powder-falling cylinder 6a to nth powder-falling cylinder 6n) are in the closed state, and the laser beam 9 is turned off.

[0030] Preferably, the vertical height of the safety clearance is set to be greater than the estimated thermal deformation warpage of the current layer's formed entity.

[0031] In the return powdering process after material switching is completed, such as Figure 3 As shown, the powder spreading component moves to the right. The powder suction nozzle 5 follows the component's movement but is in a closed or non-operating state.

[0032] Based on the material properties required for the current layer (e.g., a second material is needed), the device controls only the corresponding second powder-dropping cylinder 6b to open and quantitatively drop new powder (as shown by the dotted line and powder pile in the figure), while the other powder-dropping cylinders (such as 6a and 6n) remain closed.

[0033] Simultaneously, the device drives the scraper 4 to descend to the designated working height. As the scraper 4 moves to the right, a smooth new powder layer is formed behind it (left side of the figure), covering the cleaned substrate 1 and the formed solid 2. In front of the scraper (right side of the figure), the space remains clean, awaiting the application of powder material. This process achieves precise material displacement between layers.

[0034] like Figure 4 As shown, this embodiment also provides a dynamic control method for multi-material additive manufacturing, including the following steps: Read the target material corresponding to the current printing task and determine whether the target material is the same as the type of residual powder on the current substrate; When the judgment result is different, the powder spreading component is controlled to collect the residual powder on the substrate surface during the outward reciprocating motion along the substrate surface, and to spread the target material on the substrate surface during the return stroke. When the judgment results are the same, if two adjacent printing tasks are on different printing layers, the powder spreading component needs to be controlled to spread the target material on the substrate surface during the outward and / or return strokes of the reciprocating motion along the substrate surface. This is called adding powder to the target material before laser scanning printing is performed.

[0035] In two printing jobs with the same printing layer, the powder spreading component does not need to perform the same powder spreading operation on the same target material again, and can directly perform laser scanning printing.

[0036] Specifically, before starting the current printing task, this method first retrieves the next set of printing tasks to be executed from the optimized queue and determines its target material. Then determine the target material. Is it related to residual powder? same.

[0037] If they differ, a switching and cleaning strategy is implemented. This controls the diversion valve 10 to switch the powder suction line to the path where residual powder remains. The corresponding recycling container.

[0038] Then, the powder spreading component is controlled to perform the outward motion. During this motion, the powder suction nozzle 5 is opened to remove residual powder. At the same time, the scraper 4 is driven to perform a lifting action, so that its bottom surface is higher than the top surface of the formed solid 2, forming a safe clearance gap to prevent the scraper from colliding with the solid.

[0039] Finally, the return stroke with powder spreading is performed. During this process, the control scraper descends to the working height and, according to the target material... Selectively open the corresponding powder discharge cylinder for quantitative feeding.

[0040] If the target material With the current residual powder If the conditions are the same, the current state of powder bed 3 is maintained, the cleaning step is skipped, and existing powder is used directly or only incremental powder spreading is done, thereby improving efficiency.

[0041] Then, the galvanometer scanning system 8 selectively melts and sintersulates the newly laid powder layer based on the slice data of the current task group. Simultaneously, after the current task group is completed, the status record is updated, and the residual powder type is updated to the current material for use as a benchmark in the next assessment. Through this process, the present invention achieves an optimal balance between efficiency, safety, and cost.

[0042] In addition, such as Figure 5As shown, this method includes the following steps before starting all printing tasks for the current layer: Obtain the current residual powder type on the substrate surface and read all print job files for the current layer to form an execution queue; The tasks are grouped according to the properties of the target material corresponding to each print task file. When there is a task group with the same properties as the target material and the residual powder type, the task group with the same properties is moved to the first position in the execution queue.

[0043] Specifically, when starting the printing process for the Nth layer, the system first reads the manufacturing data file to be printed for the current layer (such as a slice file or path planning file) and parses the target material properties and slice layer thickness information contained therein.

[0044] A dynamic sorting algorithm is then executed. Based on the target material properties and layer thickness information, the task is divided into several homogeneous task groups, and the queue is checked to see if any tasks match the type of residual powder. Task groups with identical attributes. If such groups exist, move them to the front of the queue to establish a priority order for execution.

[0045] Then, the sensor or system records the type of residual powder currently covering the substrate surface. (i.e., powder left over from the previous layer or task). If the queue contains target material and residual powder type... For tasks in the same group, move the group to the front of the queue to prioritize printing materials with the same properties, thereby minimizing the number of material changes.

[0046] The specific embodiments described herein are merely illustrative of the spirit of the invention. Those skilled in the art to which this invention pertains may make various modifications or additions to the described specific embodiments or use similar methods to substitute them, without departing from the spirit of the invention or exceeding the scope defined by the appended claims.

[0047] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0048] Furthermore, in this invention, descriptions involving terms such as "first," "second," and "a" are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0049] In this invention, unless otherwise explicitly specified and limited, the terms "connection," "fixed," etc., should be interpreted broadly. For example, "fixed" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection or an electrical connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0050] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

Claims

1. A dynamic control method for multi-material additive manufacturing, characterized in that, Includes the following steps: Read the target material corresponding to the current printing task and determine whether the target material is the same type as the residual powder on the current substrate; When the judgment result is different, the powder spreading component is controlled to collect the residual powder on the substrate surface during the outward reciprocating motion along the substrate surface, and to spread the target material on the substrate surface during the return stroke. If the results are the same, determine whether the current print job and the previous print job are located on the same print layer. If located on different printing layers, the powder spreading component is controlled to spread the target material on the substrate surface during the outward and / or return strokes of reciprocating motion along the substrate surface.

2. The dynamic control method for multi-material additive manufacturing according to claim 1, characterized in that, Before starting all printing tasks for the current layer, the following steps are also included: Obtain the current residual powder type on the substrate surface and read all print job files for the current layer to form an execution queue; The target materials for each printing task file are grouped according to their properties. When there is a task group with the same properties as the target material and the residual powder type, the task group with the same properties is moved to the first position in the execution queue.

3. The dynamic control method for multi-material additive manufacturing according to claim 1, characterized in that, The powder-laying assembly includes a powder-suction nozzle; the powder-suction nozzle is configured to suck up residual powder on the substrate surface or lay the target material on the substrate surface when it reciprocates along the substrate surface.

4. The dynamic control method for multi-material additive manufacturing according to claim 3, characterized in that, The powder spreading assembly also includes a scraper configured to move in a direction perpendicular to the direction of movement of the powder suction nozzle.

5. The dynamic control method for multi-material additive manufacturing according to claim 4, characterized in that, During the outward stroke of the powder suction nozzle, the scraper is configured to perform a lifting action so that its bottom surface is higher than the top surface of the currently formed solid layer and forms a clearance gap; and during the return stroke of the powder suction nozzle, the scraper is configured to perform a lowering action to spread the powder on the substrate surface.

6. The dynamic control method for multi-material additive manufacturing according to claim 5, characterized in that, The vertical height of the clearance is configured to be greater than the estimated thermal deformation warpage of the current layer's formed entity.

7. A dynamic control device for multi-material additive manufacturing, characterized in that, include: A powder supply assembly includes at least two powder dispensing cylinders, wherein the powder dispensing cylinders store powder material corresponding to the printing task. The diversion and recycling component includes at least one recycling container, each of which corresponds to a powder material in the powder drop cylinder. A powder spreading assembly is connected to the powder discharge cylinder and the recycling container respectively, and reciprocates on the substrate surface; the powder spreading assembly is configured as follows: After determining that the type of powder remaining on the current substrate surface is different from the target material corresponding to the next printing task, the residual powder material on the substrate surface is collected into the recycling container during the outward reciprocating motion along the substrate surface, and the target material is extracted from the corresponding powder drop cylinder and laid on the substrate surface during the return stroke.

8. The multi-material additive manufacturing dynamic control device according to claim 7, characterized in that, The powder spreading assembly includes a powder suction nozzle and a scraper; the powder suction nozzle is configured to pick up residual powder on the substrate surface when it reciprocates along the substrate surface; the scraper is configured to move in a direction perpendicular to the direction of movement of the powder suction nozzle.

9. The multi-material additive manufacturing dynamic control device according to claim 8, characterized in that, The powder discharge cylinders are arranged in an array, and each powder discharge cylinder is independently controlled to open and close.

10. The multi-material additive manufacturing dynamic control device according to claim 8, characterized in that, The diversion and recycling assembly includes a diversion valve, the front end of which is connected to the powder suction nozzle, and the rear end is connected to a recycling container that corresponds one-to-one with the material of the powder discharge cylinder; when the powder suction nozzle sucks up the residual powder on the surface of the substrate, the residual powder flows into its corresponding recycling container through the switching of the diversion valve.

Images