Powder spreading device, additive manufacturing equipment and control method

Abstract

The invention provides a powder spreading device for additive manufacturing equipment. Comprising a powder laying arm capable of moving in the powder laying direction, a supporting base connected with the powder laying arm, and a powder laying component installed on the supporting base and used for evenly laying powder on a working face under driving of the powder laying arm to form a powder layer. The vibration component is installed on the supporting base and used for applying vibration in the powder laying direction in the powder laying process so as to act on a powder layer, and the vibration limiting part is connected with the supporting base and the powder laying arm and used for limiting vibration of the vibration component in the vertical direction.

Description

Technical Field

[0001] The present application relates to the field of additive manufacturing, and more specifically to a powder spreading device for additive manufacturing equipment, additive manufacturing equipment including the powder spreading device, and a control method for the powder spreading device. Background Art

[0002] In powder bed-based additive manufacturing technology, how to evenly lay powder (especially ultrafine powder) is a current challenge. Uniform powder laying directly affects the subsequent manufacturing process, thereby affecting the density, mechanical properties and surface quality of the component. However, due to the poor fluidity of ultrafine powders and their susceptibility to van der Waals forces and static electricity, problems such as accumulation, uneven distribution, and voids often occur during the powder laying process. These undesirable powder laying effects can lead to defects such as pores, interlayer separation, and uneven surface roughness during the manufacturing process, thereby limiting the forming accuracy and performance of additively manufactured parts. Summary of the invention

[0003] The present application proposes a powder spreading device, additive manufacturing equipment and a control method to improve the uniformity of powder spreading.

[0004] One aspect of the present application provides a powder spreading device for additive manufacturing equipment, the powder spreading device comprising: a powder spreading arm, which can move along the powder spreading direction; a support seat, which is connected to the powder spreading arm; a powder spreading component, which is installed on the support seat and is used to evenly spread the powder on the working surface driven by the powder spreading arm to form a powder layer; a vibration component, which is installed on the support seat and is used to apply vibration along the powder spreading direction to act on the powder layer during the powder spreading process; and a vibration limiting part, which is respectively connected to the support seat and the powder spreading arm, and is used to limit the vibration of the vibration component in the vertical direction.

[0005] Preferably, the vibration limiting portion limits the vibration amplitude of the vibration component in the vertical direction to be smaller than the vibration amplitude of the vibration component in the horizontal direction.

[0006] Preferably, the vibration limiting portion limits the vibration amplitude of the vibration component in the vertical direction to be less than at least half of the vibration amplitude in the horizontal direction.

[0007] Preferably, the vibration limiting part is provided with a single or multiple thin-wall structures in the vertical direction.

[0008] Preferably, the material of the vibration limiting part is selected from any one of nylon, carbon fiber nylon, stainless steel and engineering plastics.

[0009] Preferably, the tensile strength of the vibration limiting portion is greater than 100 MPa, and satisfies the yield strength range between 50 MPa and 200 MPa, and the damping coefficient is greater than 0.05.

[0010] Preferably, the powder spreading arm is connected to the vibration limiting part via a zero point positioning system.

[0011] Preferably, the vibration component is driven by one or more of pneumatic drive, magnetic drive, motor drive and ultrasonic drive.

[0012] Preferably, when the vibration component is magnetically driven, the vibration component is set to have a preset distance relative to the powder layer so that the powder layer is outside the magnetic field influence area formed by the vibration component, or is within the magnetic field influence area but does not cause powder magnetization.

[0013] Preferably, it further comprises a lifting component, wherein the lifting component is connected to the vibrating component and is used to move the vibrating component to a position having the preset distance relative to the powder layer.

[0014] Preferably, at least one end of the powder spreading component in contact with the powder is configured to be any one of a rubber strip, a brush, ceramic and metal.

[0015] Preferably, when the D90 particle size of the powder used is less than 20 μm, at least one end of the powder spreading component in contact with the powder is set to a rubber strip or a brush; when the D90 particle size of the powder used is greater than or equal to 20 μm, at least one end of the powder spreading component in contact with the powder is set to a ceramic or metal block.

[0016] Preferably, at least one end of the powder spreading component in contact with the powder is provided with one or more arc-shaped protrusions, and the shape of the arc-shaped protrusions is a long-side shape of an ellipse.

[0017] Preferably, the vibrating component is movably connected to the support seat and the powder spreading arm respectively through a limiting structure, and the limiting structure is used to limit the movable range of the vibrating component and allow the vibrating component to move in at least one direction within the range.

[0018] One aspect of the present application provides an additive manufacturing device, which includes the powder spreading device described in any one of the above items. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The accompanying drawings, which are incorporated herein and form a part of the specification, illustrate one or more embodiments of the present application and, together with the description, serve to explain the principles of the present application and to enable one of ordinary skill in the relevant art to make and use the present application.

[0020] Figure 1 It is an image of laying a powder bed according to a vibrating powder laying device with an integrated vibration reduction device in the prior art;

[0021] Figure 2is a schematic structural diagram of a powder spreading device according to some embodiments of the present application;

[0022] Figure 3 is a schematic diagram of the installation of a powder spreading device and a forming cabin according to some embodiments of the present application;

[0023] Figure 4 This is a schematic diagram of a model of a powder spreading device according to some embodiments of the present application.

[0024] Figure 5 The structure of the powder spreading device according to some embodiments of the present application and its arrangement in practical application;

[0025] Figure 6 The structure of the powder spreading device according to some embodiments of the present application and its arrangement in practical application;

[0026] Figure 7 and Figure 8 They are schematic diagrams of the structure of the powder spreading component according to some embodiments of the present application;

[0027] Fig. 9 is a schematic structural diagram of a powder spreading device according to some embodiments of the present application;

[0028] Fig.10 is an image of a powder bed laid by a powder laying device according to some embodiments of the present application;

[0029] Fig.11 is a schematic structural diagram of a vibration limiting unit according to some embodiments of the present application;

[0030] Fig.12 This is a graph of vibration measurement experimental data during the operation of the powder spreading device according to some embodiments of the present application.

[0031] Like reference numerals refer to like elements throughout the drawings and detailed description. The drawings may not be drawn to scale, and the relative size, proportions, and depiction of elements in the drawings may be exaggerated for clarity, illustration, and convenience. DETAILED DESCRIPTION

[0032] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments.

[0033] Additive manufacturing technology, also known as 3D printing technology, is an advanced manufacturing process that manufactures complex structures by accumulating materials layer by layer. There are many types of this technology, suitable for different materials and process requirements. For example, common additive manufacturing technologies include laser powder bed melting (LPBF), selective laser melting (SLM), selective laser sintering (SLS), electron beam melting (EBM), fused deposition modeling (FDM) and stereolithography (SLA). Including but not limited to LPBF, SLM, SLS and EBM, they can be classified as powder bed-based additive manufacturing technologies. The common feature of this type of technology is the use of high-energy beams (such as lasers or electron beams) to melt or sinter the powder materials laid on the building platform layer by layer to form and manufacture parts.

[0034] In order to solve the problem of poor powder spreading uniformity described in the background technology, the prior art, such as CN113458421A, has proposed a solution of setting a vibration device in the powder spreading device. This solution aims to improve the uniformity of powder laying by applying vibration during the powder spreading process to break the clusters or adhesions of powder particles. However, in order to reduce the impact of vibration transmission to the main body of the powder spreading device, the solution also introduces a vibration reduction unit into the device. Although the vibration reduction unit reduces the transmission and negative impact of vibration on the entire equipment to a certain extent, this design brings some new problems. First, the vibration energy is partially absorbed by the vibration reduction unit, so that the applied vibration effect cannot be efficiently used to improve the powder distribution. Secondly, vibration will still be generated in the Z-axis direction (i.e., perpendicular to the up and down direction of the powder layer), and the vibration in this direction will cause the current powder layer to form tiny wave-like fluctuations (refer to Figure 1 ), and due to the poor fluidity of ultrafine powder, this fluctuation will hinder the stable laying and uniformity of the subsequent forming layer. In addition, the vertical vibration not only affects the flatness of the powder layer, but also transmits the vibration component to the powder laying arm, affecting the stability of the entire system. These problems limit the application of existing technologies in high-precision component manufacturing, especially when it comes to complex component manufacturing involving ultrafine powder.

[0035] To this end, an embodiment of the present application provides a powder spreading device to solve the above-mentioned problems.

[0036] Figure 2 1 is a schematic diagram of the structure of a powder spreading device according to some embodiments of the present application. The powder spreading device 10 can be applied to an additive manufacturing device, and is specifically arranged inside the additive manufacturing device, and more specifically arranged inside a forming cabin of the additive manufacturing device. Figure 2 In the embodiment of the present invention, the powder spreading device 10 is configured to include a powder spreading arm 11, a support seat 12, a powder spreading component 13, a vibration component 14, a vibration limiting part 15 and other components.

[0037] The powder spreading arm 11 is configured to move along the powder spreading direction (X axis) in the additive manufacturing device so that the powder is evenly distributed on the working surface V. The powder spreading arm 11 can be driven by a moving device (such as an automatic guide rail) arranged on the inner wall of the forming chamber. In terms of specific structure, the powder spreading arm 11 can be directly connected to the moving device, or indirectly fixed to the moving device through a connecting structure. The powder spreading arm 11 and the connecting structure are, for example, configured to be detachably connected to facilitate the overall disassembly and assembly of the powder spreading device 10.

[0038] The support seat 12 is used to carry part of the components of the powder spreading device 10, especially the installation of the powder spreading component 13. The powder spreading component 13 is installed on the support seat 12, specifically located at the lower end of the support seat 12, facing the working surface V, to ensure that it can contact the surface of the powder during the powder spreading process. The powder spreading component 13 can be in the form of a scraper or a roller, which is selected according to different powder types and process requirements. The scraper can provide precise control of the powder layer thickness, while the roller is suitable for smooth laying over a larger area. Driven by the powder spreading arm 11, the powder spreading component 13 evenly spreads the powder on the working surface V, thereby forming an ideal powder layer.

[0039] The vibration component 14 is installed on the support base 12, specifically on the upper end of the support base 12, and is an important component for achieving uniform powder laying. The vibration component 14 can generate vibration during the powder laying process, and can control the vibration to be transmitted to the powder layer, breaking the clustering or adhesion of powder particles, reducing the uneven distribution caused by poor powder fluidity, and thus improving the laying quality. The vibration component 14 can adopt a variety of vibration forms to meet the vibration requirements of different powder characteristics and improve the powder laying efficiency and forming effect.

[0040] In order to solve the problem that vibration energy cannot be effectively utilized and will cause undulation transmission in the Z-axis direction in the prior art, the embodiment of the present application provides a vibration limiting part 15, which is configured to be connected to the support seat 12 and the powder spreading arm 11 respectively, and is used to limit the vibration of the vibration component 14 in the vertical direction. By limiting the amplitude of the vertical vibration, that is, the vertical vibration generated by the vibration component 14 during operation is limited to a smaller range, the wave-shaped unevenness on the powder layer caused by excessive vibration amplitude is avoided, the uniformity of powder spreading and the close contact between layers are maintained, and the transmission of vibration to the powder spreading arm 11 and other components is reduced, and the stability of the system is maintained.

[0041] Fig.11It is a schematic diagram of the structure of the vibration limiting part according to some embodiments of the present application. The vibration limiting part 15 is provided with multiple thin-walled wall structures 151 in the vertical direction, which can regulate the vibration in other directions while limiting the amplitude of the Z and Y axes. An important feature of this thin-walled structure is that its thickness in the X-axis direction is much lower than its length in the Y-axis and Z-axis directions, thereby forming an array of thin-walled structural components. This structure can be expected to have a good support and limit the vibration amplitude in the Y-axis and Z-axis directions, and at the same time play an amplitude guiding role in the X-axis direction of the desired vibration. The vibration limiting component proposed in the present application can adjust the amplitude of vibration in three directions by adjusting the dimensions of the thin-walled structure of the vibration limiting part in the X, Y, and Z directions according to the needs of the actual vibration amplitude. Specifically in the present embodiment, it is hoped that the Z-axis amplitude is as small as possible, and the vibration limiting part of the present application can play a good regulating role. It should be understood that in some other embodiments, it is also possible to hope that the Y-axis has a certain amplitude, and the purpose can also be achieved by adjusting the size ratio of the vibration limiting part. In the X-axis direction, the thin-walled wall structure 151, through its small thickness and arrangement, enables the vibration to maintain the necessary degree of freedom in the X-axis, thereby generating effective vibration frequency and amplitude when needed. This is particularly important for improving the dispersion of powders and eliminating agglomeration, and can significantly improve the uniformity of powder spreading. In the Z-axis direction, the thin-walled wall structure 151 forms an integral support network, thereby enhancing the rigidity and stability of the vibration limiting part 15, and effectively preventing excessive propagation of vibration in the vertical direction and the Y-axis direction.

[0042] In terms of specific structure, the vibration limiting part 15 can be designed as a support rod, a frame or a bracket, etc., connected between the powder spreading arm 11 and the support seat 12. In some embodiments, the vibration limiting part 15 can also be designed as a part extending upward from the support seat 12, or a part extending downward from the powder spreading arm 11.

[0043] It should be understood that one purpose of limiting the vibration amplitude is to reduce the impact of vertical vibration on the powder layer. Excessive vertical vibration will cause the powder to form an irregular wavy texture when it is laid. This phenomenon is particularly significant when the ultrafine powder has poor fluidity. The wavy surface can easily cause the adhesion of subsequent printed layers to weaken, thereby causing problems such as interlayer separation, printing defects and uneven surface quality. Therefore, by strictly limiting the vertical vibration amplitude of the vibration component 14 to a smaller range through the vibration limiting part 15, the occurrence of the above-mentioned problems can be effectively prevented, ensuring the uniformity of powder laying in each layer. Therefore, it is not recommended to select materials with vibration-damping properties, such as flexible materials such as vibration-damping rubber pads, for the material of the vibration limiting part 15, but rather some engineering plastics or metal materials with a certain strength should be selected.

[0044] It should also be understood that Fig.11What is provided is only a schematic structure of the vibration limiting part. The array structure of the three-layer thin sheets shown in the figure is only a structure with a better limiting effect tested by the inventor. In actual tests, even a single-layer thin sheet structure can play a certain limiting and guiding role. This is mainly related to the material selected for the vibration limiting part. For example, the use of carbon fiber short fiber composite resin material has a better elastic modulus than pure resin material, so the number of array sheets can be reduced. In practice, engineers and technicians in this field can obtain a structure that is composite of actual working conditions in limited experimental tests according to actual needs. For this reason, they should all be within the scope of protection requested in this application.

[0045] In some embodiments, the powder spreading device 10 may further be provided with a limit pin structure on the basis that the vibration limiting part 15 is respectively connected to the support seat 12 and the powder spreading arm 11. The limit pin may be provided at the connection between the vibration limiting part 15 and the support seat 12 and / or the powder spreading arm 11. As a mechanical limit element, the limit pin serves to further limit the vibration of the vibration component 14 in the Z-axis direction, thereby avoiding excessive transmission of vibration to the main body of the powder spreading device.

[0046] In the embodiment of the present application, the vibration limiting unit 15 can limit the vibration amplitude of the vibration component 14 in the vertical direction to be smaller than the vibration amplitude in the horizontal direction, so as to optimize the utilization of vibration energy and make the vibration act more in the horizontal direction (X-axis and / or Y-axis), thereby improving the powder laying effect. Exemplarily, the vibration limiting unit 15 limits the vibration amplitude in the vertical direction to be less than more than half of the vibration amplitude in the horizontal direction. That is to say, in actual operation, even if the vibration component 14 has a significant vibration amplitude in the horizontal direction (for example, applying vibration to help the powder particles disperse), its vibration in the vertical direction will be greatly limited to ensure that the powder layer is not disturbed by excessive vertical fluctuation amplitude when being laid.

[0047] In some embodiments, the material of the vibration limiting part 15 can be selected as nylon material. As an engineering polymer material, it has high strength and good impact resistance. As the material of the vibration limiting part 15, the lightweight property of nylon reduces the load of the overall device and reduces the restriction on the moving speed of the powder spreading device 10. In addition, the heat resistance of the nylon material is sufficient to cope with the higher temperature fluctuations in additive manufacturing, especially the modified nylon material, which can maintain stable shape and performance under complex conditions.

[0048] In some embodiments, the material of the vibration limiting part 15 can be selected as carbon fiber nylon. Carbon fiber reinforced nylon is a traditional nylon with carbon fiber added, which has higher rigidity and better tensile strength. The high strength and low density of carbon fiber nylon make it a better choice for the vibration limiting part 15, because it can maintain a low weight while providing rigid support. More importantly, the addition of carbon fiber gives the material good fatigue resistance, can remain stable in a long-term and high-frequency vibration environment, and also has a low thermal expansion coefficient, and will not significantly deform or fail under temperature fluctuations.

[0049] In some embodiments, the material of the vibration limiting part 15 can be selected as stainless steel, such as 316L. The main advantage of stainless steel as the material of the vibration limiting part 15 is its excellent mechanical strength. Stainless steel has high tensile strength and good toughness, and can maintain the stability of the structure under large loads. Its high temperature resistance is very suitable for working conditions involving high-temperature powder laying in additive manufacturing, and it can maintain good oxidation resistance even in extreme environments. In addition, the rigidity of stainless steel ensures that the vertical vibration of the vibrating component 14 is strictly limited, thereby effectively reducing the vibration transmission to other parts of the equipment.

[0050] In some embodiments, the material of the vibration limiting part 15 may also be selected as engineering plastics, such as polyamide-imide (PAI) or polyetheretherketone (PEEK).

[0051] In some embodiments, the vibration limiting portion has a tensile strength greater than 100 MPa, satisfies a yield strength range of 50 MPa to 200 MPa, and has a damping coefficient greater than 0.05.

[0052] Tensile strength is the maximum stress value that a material can withstand before being stretched to fracture. This property is more important for the vibration limiting part 15 because the part needs to have sufficient structural strength to resist various mechanical forces applied to it. In the powder spreading device 10, the vibration limiting part 15 needs to face the continuous vibration and mechanical impact, so its tensile strength must be high enough to ensure that it will not be damaged or fatigued due to stress accumulation.

[0053] In addition, the yield strength between 50MPa and 200MPa enables the material to withstand permanent deformation within a certain range without yielding. The yield strength refers to the stress that a material can withstand before irreversible deformation occurs. During the powder spreading process, due to the frequent movement of the vibrating component 14, the vibration limiting part 15 needs to have a moderate yield strength to resist mechanical deformation and avoid permanent deformation after being subjected to force.

[0054] In order to further suppress vibration transmission and reduce unnecessary rebound, the vibration limiting part 15 in some embodiments also requires a damping coefficient greater than 0.05. The damping coefficient is a parameter that measures how a material absorbs vibration energy and converts it into heat energy. High damping coefficient materials can effectively reduce the duration and intensity of vibration and prevent vibration from rebounding repeatedly in the Z-axis direction. Therefore, designing a damping coefficient greater than 0.05 can ensure that the vibration limiting part 15 can fully absorb and dissipate vibration energy, thereby achieving stable operation of the powder spreading device 10 and reducing fluctuations and unevenness in the powder layer due to vibration transmission.

[0055] In addition, in a possible implementation, the Poisson's ratio (μ) of the vibration limiting portion 15 can also be limited, for example, set to less than 0.35, so as to avoid significant lateral expansion of the material after being subjected to force. A lower Poisson's ratio indicates that the material has less lateral deformation when subjected to force, reducing the lateral displacement under high-frequency vibration conditions, thereby avoiding structural instability caused by vibration.

[0056] In order to distinguish the material selection of the vibration limiting part 15, combined with the above analysis, it is not desirable for the material selection to have a small elastic modulus. The material with a small elastic modulus is suitable for the vibration reduction problem mentioned in this application, but the vibration reduction material cannot effectively reduce the vibration amplitude. For example, the elastic modulus of the vibration reduction material is usually small, about within 0.2GPa, and the elastic modulus of the vibration limiting part 15 material mentioned in this application is preferably above 2GPa. According to the test results of the inventor, the fiber-reinforced PEEK material with an elastic modulus of 10GPa is the best, and the 316L stainless steel material with an elastic modulus of 190GPa also has a good vibration limiting effect, which can well solve the influence of the Z-axis vibration generated during the printing process on the powder bed powder.

[0057] Figure 3 It is a schematic diagram of the installation of a powder spreading device and a forming chamber according to some embodiments of the present application. Figure 4 is a schematic diagram of a powder spreading device according to some embodiments of the present application. Figure 3 and Figure 4 As shown, the powder spreading device 10 is provided with a shell 17 to stabilize the structure of the entire powder spreading device 10. The vibration limiting part 15 is fixed on the shell 17, and the shell 17 is connected to the powder spreading arm 11. Under this structural setting, the role of the shell 17 is extended to a part of the vibration limiting part 15, ensuring that the device can effectively limit the propagation of vibration during operation. By integrating the vibration limiting part 15 into the shell 17, it is possible to limit the propagation path in the vertical direction when vibration is generated, thereby preventing excessive diffusion of vibration energy and effectively preventing unevenness and fluctuation of the powder layer caused by vertical vibration.

[0058] The powder spreading arm 11 and the shell 17 can be connected by a zero-point positioning system 16. During the installation process, the shell 17 and the powder spreading arm 11 are first preliminarily aligned, and the positioning holes on the shell 17 are used to match the alignment device of the powder spreading arm 11. When the two are aligned, the zero-point positioning system 16 is fixed by bolts and steel balls. Specifically, the steel balls at the bottom of the zero-point positioning system 16 are designed to just pass halfway through the edge of the positioning hole of the shell 17. When the locking bolts at the top of the zero-point positioning system 11 are tightened, the internal balls will be squeezed outward by the mechanical device and press the edge of the positioning hole. At this time, the shell 17 will be firmly fixed on the powder spreading arm 11 to ensure that the entire structure remains stable when subjected to vibration and force. Through the fixation of the zero-point positioning system 16, the speed of installation and disassembly can be increased and the reliable matching of each component can be ensured by high-precision positioning, which is particularly important for reducing the error caused by vibration during the operation of the device, ensuring that the propagation of vibration in the Z-axis direction is controlled, and reducing unnecessary fluctuations in the powder spreading process.

[0059] The vibration component 14 can be driven in different ways. For example, in some embodiments, the vibration component 14 can be driven pneumatically, using compressed air as a driving method of the power source, and the vibration frequency and amplitude are controlled by adjusting the air pressure to optimize the powder spreading process. More preferably, argon can be selected as the vibration gas source. The inventor has found in practice that argon vibration has better vibration drive than compressed air and nitrogen, and can drive the vibration component more stably. The main reason is that argon is generally dried and has a different molecular weight from air, so it has a better drive for the stability of starting the piston movement. For example, in some embodiments, the vibration component 14 can be driven by electromagnetic drive, driven by electromagnetic force, and the magnetic field strength is adjusted by controlling the current, thereby changing the vibration characteristics. For example, in some embodiments, the vibration component 14 can be driven by a motor, that is, a rotating motor is used to drive the vibration device, and the rotational motion is converted into vibration through a mechanical transmission method. For example, in some embodiments, the vibration component 14 can be driven by ultrasonic drive, using high-frequency sound waves to generate vibration. Due to its high action frequency, the vibration generated by ultrasonic drive has the characteristics of small amplitude and high frequency. In addition, the vibration component 14 can also be combined with the above-mentioned multiple driving methods. For example, the combination of magnetic drive and ultrasonic drive can provide fast response while maintaining high-frequency vibration at small amplitude, achieving the superposition of multiple advantages.

[0060] Figure 5It is based on the structure of the powder spreading device of some embodiments of the present application and its arrangement in practical application. Specifically, when the vibration component 14 is magnetically driven, the vibration component 14 is set to have a preset distance L1 relative to the powder layer, so that the powder layer is outside the magnetic field influence area M formed by the vibration component 14, so as to avoid the magnetic field from producing unnecessary magnetization effects on the powder material, especially when processing powders with magnetic components. It is more important. Once the powder material is magnetized, it will easily lead to an increase in the attraction between the particles, thereby causing aggregation and agglomeration, affecting the uniformity of the powder spreading and weakening the bonding effect between layers in the subsequent molding process. By setting the vibration component 14 at a preset distance L1 from the powder layer, it is ensured that the influence of the magnetic field does not affect the powder layer, and the fluidity and laying uniformity of the powder are maintained.

[0061] Figure 6 It is a powder spreading device structure according to some embodiments of the present application and its arrangement in practical application. The vibrating component 14 is magnetically driven and is set to maintain a preset distance L2 from the powder layer, so that the powder layer is within the magnetic field influence area M but in the interval M2 that will not cause powder magnetization. The magnetic field influence area M can be divided into two parts: the interval M1 that can cause powder magnetization and the interval M2 that will not cause powder magnetization. The magnetic field strength and distance of the vibrating component 14 are designed so that the powder layer is located in the M2 area, so that the magnetic field exerts a moderate vibration effect on the powder to promote its spreading, but does not cause magnetization, avoiding the problem of mutual adsorption or aggregation of powder particles, so that the vibrating component 14 can maintain a certain vibration effect while ensuring that the physical properties of the powder are not disturbed. The setting of the preset distance L2 needs to consider many factors, including the magnetic field strength generated by the vibrating component 14, the magnetization characteristics of the powder, and the required vibration amplitude.

[0062] In some embodiments, in order to achieve the desired effect of the position of the vibration component 14 relative to the powder layer, the vibration component 14 is set to have a preset distance L1 or L2 relative to the powder layer, which can be adjusted manually or automatically. The manual adjustment can be achieved, for example, by mechanical control or manual knob. Figure 5 and Figure 6 The laying device 10 may be provided with a lifting component 18, which can move the vibrating component 14 to a position with a preset distance L1 or L2 relative to the powder layer according to the command of the control system. The control system can monitor the position of the vibrating component 14 in real time, calculate the specific range of the magnetic field influence area M formed by the vibrating component 14 in combination with the sensor data and the preset parameters, and control the action of the lifting component 18 according to the detected distance between the vibrating component 14 and the powder layer, so that the vibrating component 14 is kept at a position with a distance L1 or L2 relative to the powder layer.

[0063] For example, when the control system determines whether the powder layer is located in the magnetic field influence area M, it can use the built-in algorithm and sensor to perform position calibration and parameter calculation. The magnetic field influence area M can be defined and adjusted according to the magnetic field strength, direction and physical properties of the powder. For example, when the powder layer needs to be kept outside the M area, the control system will adjust the lifting component 18 to keep the vibration component 14 at a distance L1; and when the powder layer needs to be placed in the M2 area that will not cause magnetization, the system can adjust the lifting component 18 to keep the vibration component 14 at a distance L2, so that the operating position of the vibration component 14 always meets the predetermined standard to achieve the best effect on powder laying.

[0064] In some embodiments, in order to optimize the powder spreading effect, at least one end of the powder spreading component 13 in contact with the powder (the entire powder spreading component 13 can also be set to different materials to adapt to different powder particle sizes, including but not limited to rubber strips, brushes, ceramics and metals.

[0065] On the one hand, the rubber strip and brush materials are soft and have good elasticity, and can more effectively transfer vibrations to the powder when in contact with the powder. This feature is particularly important because by transferring vibrations to the powder, the powder can be evenly distributed during the laying process, reducing gaps and unevenness between layers. The inventors found that when using metal powder with a D90 particle size of less than 25μm, this relatively soft material can provide moderate pressure and vibration to prevent the powder from agglomerating or sticking during laying. The fine hairs of the brush can gently smooth the powder surface during the powder laying process, ensuring that small particles of powder are not scraped or moved during laying, thereby improving the flatness between layers. On the other hand, hard materials such as ceramics and metals have different effects when used for the powder laying component 13. Because these materials are relatively hard and have weak vibration transmission, they are more suitable for larger powder particle sizes. In the inventor's experiments, when using metal powder with a D90 particle size greater than or equal to 20μm, especially powder in the range of 20-30μm, using a ceramic or metal scraper can achieve a stable and efficient powder spreading effect. The hard material provides a more solid contact surface when scraping the powder, which can prevent larger particles from jumping or sliding during the powder spreading process, thereby achieving a more consistent powder layer.

[0066] Therefore, the embodiment of the present application also proposes an optimized powder spreading scheme for powders of different particle sizes. When the D90 particle size of the metal powder used is less than 20 μm, it is recommended that the powder spreading component 13 use a rubber strip or a brush. When the D90 particle size of the metal powder used is greater than or equal to 20 μm, the powder spreading component 13 should be a ceramic or metal block.

[0067] In the powder spreading process of the existing planar structure powder spreading component 13, a lot of powder is piled up at the front of the powder spreading component 13. Especially for powders with poor fluidity, it is often difficult to effectively form a uniform powder layer on the plane due to the stickiness and adhesion between the powders. This results in more powders gathering in some places and less powders in other places during the powder spreading process, and it is impossible to form a uniform powder layer thickness. For this reason, the powder spreading component 13 in some embodiments of the present application is provided with an arc-shaped protrusion at least on one end in contact with the powder.

[0068] Figure 7 It is a structural schematic diagram of the powder spreading component according to some embodiments of the present application. The powder spreading component 13 is specifically a scraper. The cross-section of the powder spreading component 13 in contact with the powder end is an arc-shaped convex structure, specifically a double hump structure design, that is, the powder spreading component 13 of the present application has a double hump structure, each hump structure has a transition arc, and during the powder spreading process, the arc structure first contacts the powder, and at this time the powder contacts the arc surface of the arc structure. Due to the existence of the arc structure, the friction between the powder and the surface of the powder spreading component 13 can be reduced, and the powder clogging caused by poor fluidity can be reduced. Therefore, the powder spreading component 13 of the present application can effectively avoid powder splashing or clogging at the front of the powder spreading component 13 during the powder spreading process.

[0069] The embodiment of the present application does not limit the number of arc-shaped protrusions, for example, they can be set to multiple to form a multi-hump structure, or they can be set to one to form a single hump structure. It should be understood that if the powder spreading component 13 is changed from a planar structure to a single hump structure, although it can effectively avoid the adhesion of powder, it will cause splashing during the powder spreading process, affecting the powder spreading effect.

[0070] The size of the arc of the hump of the powder-spreading component 13 in the embodiment of the present application is related to the particle size of the powder. For example, if the particle size of the powder D90 used in the additive manufacturing equipment is 40-60μm, the operator sets the diameter of the arc of the hump of the powder-spreading component 13 to 3-5mm; if the particle size of the powder D90 is 15-25μm, the operator sets the diameter of the arc of the hump of the powder-spreading component 13 to 2-4mm. The specific diameter of the arc of the hump of the powder-spreading component 13 is adjusted by the operator according to actual needs.

[0071] Figure 8It is a schematic diagram of the structure of the powder spreading component in some embodiments of the present application. In some embodiments, the surface of the powder spreading component 13 (scraper) is set to have a larger arc feature. Specifically, the arc surface where the scraper contacts the powder can adopt an elliptical long axis as the arc profile. The setting of this long axis feature transforms the contact between the scraper and the powder from point contact to line contact or surface contact, thereby significantly increasing the contact area. It should be understood that a larger contact area helps to evenly distribute the powder during the powder spreading process, and effectively solves the problem of uneven corrugated powder layers that are easily caused by traditional scrapers when spreading powder. If a contact profile with a circular or elliptical short axis is used, the contact area is smaller and is more inclined to point contact, which easily increases the probability of corrugation. The setting of the long axis feature can significantly improve the powder spreading performance, ensure the flatness of the powder layer, and further improve the powder spreading quality and processing effect. In some embodiments, Figure 8 The curved surface in contact with the powder can be a plane. Figure 8 The curved surface shown in the figure can become a theoretical plane when the bending radius is infinite. In actual tests, if the area where the scraper contacts the powder is set to a 2-5mm plane, and the plane and the two sides are transitioned by arcs, it can not only disperse the powder well, but also further reduce the corrugated morphology of the stratification on the Z axis and improve the flatness of the powder.

[0072] Fig. 9 1 is a schematic diagram of the structure of the powder spreading device according to some embodiments of the present application. In some embodiments, the vibration component 14 is movably connected to the support seat 12 and the powder spreading arm 11 respectively through a limiting structure 19, and the limiting structure 19 is used to limit the range of movement of the vibration component 15 and allow the vibration component 15 to move in at least one direction within the range.

[0073] like Fig. 9 As shown, specifically, the limiting structure 19 can be presented in the form of a limiting groove, which is configured to accommodate the two ends of the connecting rod 140 of the vibration component 15, and a limiting groove is provided on the support seat 12 and the powder spreading arm 11. The two ends of the connecting rod 140 are fixed in the limiting groove and can slide controllably within the range of the groove. In this way, the vibration component 15 can be accurately moved within its limited range to ensure the directionality of vibration transmission. For example, when the vibration component 15 is designed to move in the X-axis direction, the limiting structure 19 will allow it to vibrate freely in the X-axis direction, while remaining fixed in the Y-axis and Z-axis directions, so as to concentrate the vibration energy in the horizontal direction, making the powder spreading process more uniform and stable.

[0074] In addition, the embodiments of the present application also allow for combined limits in different directions. For example, the limit structure 19 can be set to allow active limits in the Y-axis direction, and fixed limits in the X-axis and Z-axis directions. The specific configuration can be adjusted according to the specific application requirements to achieve the optimal vibration transmission and control effect. In particular, in some cases, performing dual-axis active limits (such as the X-axis and the Y-axis) and fixing the limits in the Z-axis direction can help achieve multi-dimensional vibration transmission in the horizontal plane to promote uniform spreading and effective compaction of the powder.

[0075] In one implementation, the Z-axis can also be movably limited so that the vibration component 15 can have a certain amount of movable space in the Z-axis direction, rather than being completely fixed, so as to allow the vibration component 15 to produce controllable movement along the Z-axis direction under specific conditions to adapt to different materials or process requirements, thereby improving the uniformity of powder spreading. Specifically, the movable limit of the Z-axis can play a role in some special application scenarios, such as when it is necessary to better control the compaction degree of the powder. By allowing the vibration component 15 to be movably limited in the Z-axis direction, the distribution of the vibration force can be appropriately adjusted during powder laying, so that the powder layer can obtain a more uniform vibration effect. In addition, the movable limit of the Z-axis can also effectively reduce the uneven powder layer or powder spreading defects caused by excessive vibration, ensuring that the thickness and density of each layer of powder are more consistent.

[0076] In addition to being in the form of a limiting groove, the limiting structure 19 can also be in other forms, such as a slide rail, which is also an optional structural form. The slide rail structure can provide a smoother activity path for the vibration component 15 and enhance its controllability within a predetermined range. The slide rail has a lower friction coefficient and good guiding characteristics, which can reduce energy loss during vibration transmission and provide high stability.

[0077] Fig.10 is an image of a powder bed laid by a powder laying device according to some embodiments of the present application. Fig.10 It can be seen that the powder layer laid by the powder laying device of the embodiment of the present application significantly improves the small wavy fluctuation phenomenon of the powder layer surface commonly seen in the traditional method (refer to Figure 1 ). In the traditional powder spreading process, uneven vibration transmission or poor vibration control will cause the powder layer to form subtle irregular fluctuations, and these fluctuations will affect the overall density and structural quality of the print. However, the vibration limiting unit 15 provided in the present application effectively controls the propagation path and intensity of the vibration, so that the vibration force is reasonably limited during the powder spreading process. The vibration limiting unit 15 limits the transmission range of the vibration, especially reduces the vibration diffusion in the vertical direction, so that the vibration energy is more uniform and controlled in the horizontal direction. The function of the vibration limiting unit 15 is to suppress excess vibration rebound and unnecessary vibration propagation, so that the powder layer achieves optimal flatness during laying, and improves the thickness uniformity of each layer of material.

[0078] The present application also provides a control method for the powder spreading device 10, especially for Figure 5 or Figure 6 The control method of the powder spreading device 10 is described, and includes the following steps: first, the magnetic field influence area formed by the vibrating component is calculated to identify its scope of action; then, it is determined whether the powder layer is outside the magnetic field influence area, or within the magnetic field influence area but within a safe range that does not cause the powder to be magnetized. If the powder layer is not within these areas, the lifting component is controlled to move the vibrating component to a position at a preset distance to ensure that the powder layer will not be magnetized and maintain the quality of the powder spreading.

[0079] Fig.12 This is a graph of vibration measurement experimental data during the working process of the powder spreading device according to some embodiments of the present application. The specific measurement position is the support seat. Fig.12 As shown in the figure, the experimental data shows the speed, displacement and frequency of vibration in the three directions of X-axis, Y-axis and Z-axis, providing intuitive data support for evaluating the actual effect of the vibration limiting part. According to the experimental results, the vibration speed of the X-axis is 71mm / s, the vibration speed of the Y-axis is 6mm / s, the vibration speed of the Z-axis is 0mm / s, the vibration displacement of the X-axis is 300um, the vibration displacement of the Y-axis is 8um, the vibration displacement of the Z-axis is 2um, the vibration frequency of the X-axis is 299.9Hz / s, the vibration frequency of the Y-axis is 299.7Hz / s, and the vibration frequency of the Z-axis is 299.9Hz / s.

[0080] It can be shown that the vibration is mainly concentrated in the X-axis direction, there is very small vibration in the Y-axis direction, and the vibration in the Z-axis direction can be basically ignored. In particular, the vibration speed and displacement in the Z-axis direction are almost zero, which fully verifies the effectiveness of the vibration limiting part in suppressing vertical vibration. The limiting effect shows that the vibration limiting part of the present application can effectively limit the vibration of the vibrating component in the Z and Y-axis directions, while ensuring that the vibration characteristics in the X-axis direction are basically unaffected, thereby effectively avoiding excessive transmission of vibration to the main body of the powder spreading device, reducing the potential impact of vibration on the main body of the device and other components, and further improving the stability of the device. In addition, unlike the traditional method of reducing the impact of vibration transmission by setting a vibration reduction unit, the present application uses the setting of a vibration limiting part. It can be verified from the experimental results that the impact of vibration on the main body of the device can be effectively controlled without the need for an additional vibration reduction unit in the powder spreading device.

[0081] From the above content Figure 1It can also be clearly seen that the vibration in the Z axis and the Y axis is harmful to the laying of the ultrafine metal powder. The powder laying scheme proposed in this application can effectively reduce the effective amplitude of the Z axis and the Y axis, thereby achieving uniform laying of the ultrafine powder. It should be understood that the control process of the above method of the present application can be implemented in whole or in part by software, hardware, firmware or any other combination.

[0082] Those skilled in the art will readily appreciate other embodiments of the present application after considering the specification and practicing the contents disclosed herein. The present application is intended to cover any variations, uses or adaptations of the present application, which follow the general principles of the present application and include common knowledge or customary technical means in the art that are not disclosed in the present application. The specification and embodiments are to be regarded as exemplary only, and the present application is not limited to the precise structures described above and shown in the drawings, and various modifications and changes may be made without departing from the scope thereof.

Claims

1. A powder spreading device for additive manufacturing equipment, characterized in that: The powder spreading device comprises: A powder spreading arm, which can move along the powder spreading direction; A support seat connected to the powder spreading arm; A powder spreading component, which is mounted on the support seat and is used to spread the powder evenly on the working surface driven by the powder spreading arm to form a powder layer; a vibration component, which is mounted on the support seat and is used to apply vibration along the powder spreading direction to act on the powder layer during the powder spreading process; and A vibration limiting part is connected to the support seat and the powder spreading arm respectively, and is used to limit the vibration of the vibration component in the vertical direction.

2. The powder spreading device according to claim 1, characterized in that: The vibration limiting portion limits the vibration amplitude of the vibration component in the vertical direction to be smaller than the vibration amplitude of the vibration component in the horizontal direction.

3. The powder spreading device according to claim 2, characterized in that: The vibration limiting portion limits the vibration amplitude of the vibration component in the vertical direction to be less than half of the vibration amplitude in the horizontal direction.

4. The powder spreading device according to claim 1, characterized in that: The vibration limiting part is provided with a single or multiple thin-wall structures in the vertical direction.

5. The powder spreading device according to claim 1, characterized in that: The material of the vibration limiting part is selected from any one of nylon, carbon fiber nylon, stainless steel and engineering plastics.

6. The powder spreading device according to claim 1, characterized in that: The tensile strength of the vibration limiting part is greater than 100 MPa, and meets the yield strength range between 50 MPa and 200 MPa, and the damping coefficient is greater than 0.

05.

7. The powder spreading device according to claim 1, characterized in that: The powder spreading arm is connected with the vibration limiting part through a zero point positioning system.

8. The powder spreading device according to claim 1, characterized in that: The vibration component is driven by one or more of pneumatic drive, magnetic drive, motor drive and ultrasonic drive.

9. The powder spreading device according to claim 8, characterized in that: When the vibration component is magnetically driven, the vibration component is set to have a preset distance relative to the powder layer so that the powder layer is outside the magnetic field influence area formed by the vibration component, or is within the magnetic field influence area but does not cause powder magnetization.

10. The powder spreading device according to claim 9, characterized in that: It also includes a lifting component, which is connected to the vibrating component and is used to move the vibrating component to a position having the preset distance relative to the powder layer.

11. The powder spreading device according to claim 1, characterized in that: At least one end of the powder spreading component in contact with the powder is configured to be any one of a rubber strip, a brush, ceramics and metal.

12. The powder spreading device according to claim 11, characterized in that: When the D90 particle size of the powder used is less than 20 μm, at least one end of the powder spreading component in contact with the powder is configured as a rubber strip or a brush.

13. The powder spreading device according to any one of claims 1 to 12, characterized in that: At least one end of the powder spreading component in contact with the powder is provided with one or more arc-shaped protrusions, and the shape of the arc-shaped protrusions is a long-side shape of an ellipse.

14. The powder spreading device according to any one of claims 1 to 12, characterized in that: The vibrating component is movably connected to the supporting seat and the powder spreading arm respectively through a limiting structure, and the limiting structure is used to limit the movable range of the vibrating component and allow the vibrating component to move in at least one direction within the range.

15. An additive manufacturing device, characterized in that: The additive manufacturing equipment comprises the powder spreading device according to any one of claims 1 to 14.

16. A control method for the powder spreading device according to claim 10, characterized in that: The method comprises: Calculating the magnetic field influence area formed by the vibrating component; Determine whether the powder layer is outside the magnetic field influence area or within the magnetic field influence area but does not cause powder magnetization; Otherwise, the lifting component is controlled to move the vibrating component to a position having the preset distance relative to the powder layer.

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