In-situ control apparatus and method for inhibiting cracking in metal additive manufacturing

Abstract

The application discloses an in-situ control device and method for inhibiting metal additive manufacturing cracking, and belongs to the technical field of metal additive manufacturing. The device is provided with two pushing structures on the two sides of a core substrate which has been provided with a transverse gap, and the two pushing structures are in contact with the core substrate from the two sides of the core substrate, so that the two pushing structures assist in extruding the shrinkage of the core substrate from the two sides of the core substrate during the additive manufacturing process, and the shrinkage speed of the core substrate can match the required shrinkage speed of the formed part. The device of the application is a device for in-situ regulation and control of local structure deformation of a substrate, and can regulate and control the local deformation of the substrate in real time during the additive manufacturing process, so as to adjust the distribution and evolution of the stress field, successfully convert tensile stress into compressive stress, and effectively inhibit the generation and expansion of cracks.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of additive manufacturing, and relates to an in-situ control device and method for inhibiting cracking in metal additive manufacturing. BACKGROUND

[0002] High-energy beam metal additive manufacturing (such as laser melting and electron beam melting) melts and deposits metal powder or wire material point by point, layer by layer through a strong heat source, providing an innovative approach to the design and manufacturing of complex metal structures. This technology has wide application potential in the fields of aerospace, automobile industry and medical devices, meeting the demand for complex shapes and high performance. However, the process presents high heterogeneity and rapidity, involving multi-scale thermal, microstructure and stress coupling, with a temperature gradient of up to 10 6 K / m and a cooling rate of up to 10 6 K / s. The deposited metal undergoes multiple thermal cycles and is subjected to strong mechanical constraints from the substrate and clamps, resulting in significant thermal stress, phase transformation stress and mechanical constraint stress inside the finished product. These stresses are coupled with each other and gradually accumulated, which may lead to cracking and failure if not controlled.

[0003] In the additive manufacturing of difficult-to-weld alloys (such as nickel-based superalloy IN738), cracks often form at grain boundaries and continuously expand as the deposition layer grows. This phenomenon is particularly evident when the size and shape of the metal component are complex, and the interactions of solidification, reheating cycles and internal stress in additive manufacturing become more complex, making the cracking problem more prominent. Currently, the research on crack control in the additive manufacturing of difficult-to-weld alloys mainly focuses on the following aspects: optimizing process parameters, developing new alloy materials and applying preheating technology. Although these methods provide ideas for controlling cracks, they still face challenges in implementation and may increase manufacturing costs or affect material performance.

[0004] The published patent CN 118321575 A discloses an intelligent substrate for avoiding cracking of an additive manufacturing part. The substrate is disassembled, and a horizontal gap is opened in the core printing part of the substrate, which is not connected with the surface. During the printing process, the substrate can move horizontally once heated, reducing the mechanical constraint of the substrate on the formed part and improving the deformation coordination of the material in the heat-affected zone during expansion and contraction. However, the above technical solution is limited in crack inhibition when printing large-size parts and when multiple layers are needed in the printing process. Since the entire deformed substrate is at the bottom, the contraction ability of the substrate is difficult to completely follow the deformation speed of the formed part in the printing process, limiting the crack inhibition effect. SUMMARY

[0005] The purpose of the present application is to overcome the above-mentioned shortcomings of the prior art, provide an in-situ control device and method for inhibiting metal additive manufacturing cracking, to solve the problem that the shrinkage speed of the substrate is difficult to meet the deformation speed of the printed part in the prior art.

[0006] To achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0007] An in-situ control device for inhibiting metal additive manufacturing cracking, comprising: a base, two suspensions are slidably connected to the base, each opposite end of the two suspensions is provided with a pushing structure, the two pushing structures are arranged at the longitudinal two ends of a core substrate and abut the two sides of the core substrate respectively, and the two pushing structures are coaxial with the core substrate; and a transverse gap is arranged on the core substrate.

[0008] Further improvements of the present application are:

[0009] Preferably, the two suspensions are arranged along the transverse direction of the base.

[0010] The base is connected to the suspensions through guide rails, and each end of each suspension is slidably connected to a guide rail.

[0011] Preferably, a motor is arranged on the base, and the motor is used to drive the two ends of the suspension to move relative to the guide rail.

[0012] Preferably, the guide rail is a lead screw structure, and the two ends of the suspension are a slider structure.

[0013] Preferably, an upper panel is arranged on the base, the upper panel is fixed to the base through a support, and a slot for placing the guide rail is arranged on the upper panel.

[0014] Preferably, a top plate is arranged below the suspension, the top plate abuts the longitudinal two ends of the base, and the core substrate is arranged in the base.

[0015] Preferably, the pushing structure is in the shape of a thimble, a block or a cylinder.

[0016] Preferably, the pushing structure is in the shape of a thimble.

[0017] An in-situ control method for inhibiting metal additive manufacturing cracking based on the above-mentioned in-situ control device, in the additive manufacturing fusion deposition process, the two pushing structures push the core substrate from the two sides of the core substrate.

[0018] Preferably, the pushing speed of the pushing structure is determined according to the shrinkage speed of the core substrate.

[0019] Compared with the prior art, the present application has the following beneficial effects:

[0020] The application discloses an in-situ control device for inhibiting cracking in metal additive manufacturing, which is based on the aforementioned research and is provided with two pushing structures on the two sides of a core substrate which has been provided with transverse cracks, and the two pushing structures are in abutment with the core substrate from the two sides of the core substrate, so that in the process of the shrinkage of the core substrate during the additive manufacturing, the two pushing structures promote the shrinkage of the core substrate from the two sides, and the shrinkage speed of the core substrate can meet the shrinkage speed of the process piece in the process of the additive manufacturing of the substrate. The device of the application is a device for in-situ regulating the deformation of the local structure of the substrate, and can regulate the local deformation of the substrate in real time during the manufacturing process, so as to adjust the distribution of the stress field, convert tensile stress into compressive stress, and effectively inhibit the generation and expansion of cracks. The core of the application is to solve the non-uniform deformation of the material caused by repeated heating-cooling cycles in the process of high-energy beam additive manufacturing, and in particular, when the deposited layer is rapidly cooled and shrunk in the hot state, the deposited layer is strongly mechanically constrained by the cold substrate, and the high tensile stress accumulated layer by layer in the deposited layer becomes the main driving force for cracking. Through the dynamic deformation control of the device, the cracking risk of the part can be fundamentally reduced. The application also has the following advantages:

[0021] (1) Strong compatibility: suitable for various high-energy beam metal additive manufacturing processes such as laser, electron beam and electric arc, and widely applicable.

[0022] (2) Reducing internal stress and preventing cracking: effectively controlling internal stress in the process of additive manufacturing of difficult-to-weld alloys, preventing cracking and failure of the part, and ensuring the forming quality.

[0023] (3) Strong universality and wide process window: the device is suitable for various substrate materials, has high adaptability to process parameters, has significant crack stopping effect, and is suitable for the additive manufacturing of difficult-to-weld metals.

[0024] The application also discloses an in-situ control method for inhibiting cracking in metal additive manufacturing, which gives the core substrate a pushing force from the two sides of the core substrate to assist the shrinkage of the core substrate in the process of the shrinkage of the core substrate during the additive manufacturing. The method proposes to regulate the stress field by in-situ controlling the deformation of the local structure of the substrate to effectively control the cracks. This method not only simplifies the stress management in the additive manufacturing, but also is expected to significantly improve the forming quality and reliability of difficult-to-weld alloys. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 is a schematic view of a substrate.

[0026] Figure 2 is a structure processing diagram for the used substrate;

[0027] Figure 3 is an IN738LC nickel-based superalloy part printed without using the deformation control device;

[0028] Figure 4 a designed deformation control device;

[0029] Figure 5 a designed substrate is mounted on the deformation control device;

[0030] Figure 6 a 3D printing process using the deformation control device;

[0031] Figure 7 a crack-free IN73 nickel-based superalloy part printed using the deformation control device.

[0032] Wherein, 1, motor; 2, top plate; 3, propulsion structure; 4, suspension; 5, substrate; 6, guide rail; 7, upper panel; 8, base; 9, core substrate. DETAILED DESCRIPTION

[0033] The application will be further described in detail below with reference to the accompanying drawings:

[0034] The embodiments of the application are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference signs represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the application, and cannot be understood as a limitation of the application.

[0035] The following longitudinal direction in the application refers to the length direction of the substrate 5, which is the same as the length direction of the printed part, and the transverse direction is perpendicular to the length direction of the substrate 5.

[0036] The first aspect of the application discloses an in-situ control device for suppressing cracking in metal additive manufacturing, which comprises a motor 1, a top plate 2, a propulsion structure 3, a suspension 4, a substrate 5, a guide rail 6, an upper panel 7 and a base 8. The base 8 is slidably connected with two suspensions 4, and each end of the two suspensions 4 is provided with one propulsion structure 3, and the two propulsion structures 3 are arranged at the longitudinal ends of the core substrate 9 and abut the two sides of the core substrate 9 respectively, and the two propulsion structures 3 are coaxial with the core substrate 9. The core substrate 9 is provided with a transverse gap. The two suspensions 4 are arranged along the transverse direction of the base 8.

[0037] It should be noted that the present application is a further study of the published patent CN 118321575 A, and the disclosed core substrate 9 is S3 in the published patent CN 118321575 A. The core substrate 9 is a part of the substrate 5, which is cut from the substrate 5 and can move longitudinally relative to the substrate 5. For details of the core substrate 9, please refer to the above-mentioned published patent.

[0038] The base 8 of the device is a support structure as a whole, which is placed on the printer bed during the printing process, and is used to support the entire in-situ control device. A plurality of supports are fixedly arranged on the support structure for supporting the upper panel 7, and the area of the upper panel 7 is substantially equal to the area of the base 8.

[0039] The support structure between the base 8 and the upper panel 7 is used to place the motor 1 and the guide rail 6. The upper panel 7 is provided with four notches along the guide rail 6, and the guide rail 6 is provided with four supports, which are symmetrically arranged on both sides of the base plate 5 and respectively protrude from the notches. The suspension 4 is a rod-shaped structure, which is arranged transversely on the base 8. One end of each suspension 4 is integrally provided with a sliding block structure, which is in sliding connection with a guide rail 6.

[0040] The two ends of the guide rail 6 and the suspension 4 are screw rod connection structures. The motor 1 drives the suspension 4 to move by driving the rotation of the screw rod.

[0041] The motor 4 can be arranged in two different output power ends, which are arranged on both sides of the base 8, or one motor 4 can be arranged.

[0042] As preferred, the sliding block structures on both sides of the suspension 4 are driven by one motor 4, so that the pushing forces are the same and uniform.

[0043] Two top plates 2 are further arranged on the upper panel 7, each of which is arranged below the suspension 4. The inner end of each top plate 2 abuts one end of the base plate, and the two top plates 2 can stably fix the base plate body.

[0044] One end of the advancing structure 3 is fixedly arranged on the suspension 4, and the other end abuts one end of the core base plate 9. With the movement of the suspension 4, the two advancing structures 3 can jointly compress the core base plate 9. The axes of the two advancing structures 3 and the axis of the core base plate 9 are the same, so that the core base plate 9 can be uniformly stressed during the compression process.

[0045] It should be understood that the advancing structure 3 can be in the shape of a thimble, a block, a cylinder or other shapes, but the area of the inner end of the advancing structure 3 should be smaller than the area of the two ends of the core base plate 9, so as to ensure that the inner end of the advancing structure 3 can fully contact the end of the core base plate 9. It should be noted that the surface structure of the advancing structure 3 can be adjusted according to the area of the end of the core base plate 9, so as to give the core base plate 9 sufficient advancing force.

[0046] As preferred, the advancing structure 3 is in the shape of a thimble, so that the advancing structure is highly adaptable.

[0047] The application also discloses an in-situ control method for inhibiting cracking of metal additive manufacturing, which comprises the following steps:

[0048] 1) Selecting the substrate: mark the CAD base surface shape of the part to be printed as shape C0, design a slightly larger rectangular shape C1 that completely covers C0 and makes C1 slightly larger than C0. Select a block plate with a thickness of usually more than 12 mm as the substrate R, and its horizontal cross-sectional dimension is generally greater than shape C1 (about 3 to 10 times C1). Align the center of C1 with the center of the upper surface of the substrate, determine the deposition area C2 of printing, and make C2 equal to C1.

[0049] 2) Processing the substrate structure: take out the upper part of the substrate corresponding to the C2 area from the substrate R, and mark it as R1. The specific steps include first sawtooth cutting in the vertical thickness direction along the long side of C2 rectangle, and then horizontal cutting along the plane parallel to C2, with a cutting depth of 3 to 7 mm and a horizontal cutting distance consistent with the width of C2. At this time, the substrate R is divided into R1 part and the remaining substrate body R2, and R1 can only move in the horizontal plane and cannot move in the vertical direction.

[0050] 3) Cutting the gap: cut a series of gaps in the vertical direction of R1 from bottom to top, which are parallel to the horizontal long side direction of R1, with a spacing of 3 to 8 mm, and ensure that the upper surface of R1 is not completely cut off. The processed R1 is marked as core substrate R3. The design substrate containing R2 and R3 is marked as substrate DR.

[0051] 4) Building a deformation control device: build a work platform with two top pins on the top of both sides, which can move towards or away from each other on the same track, and the moving speed is the same and controlled by the rotation of the lead screw on the track, and the moving speed is automatically controlled by the motor.

[0052] 5) Install the design substrate on the deformation control device: assemble and fix the design substrate R2 and the core substrate R3 on the deformation control device, so that the two ends of the core substrate R3 are in contact with the top pins and they remain coaxial.

[0053] 3D printing process stress control: set appropriate additive manufacturing process parameters, and perform layer-by-layer printing in the C2 area of the design substrate, while using the in-situ deformation control device to gradually compress the substrate R3 along the length direction of the substrate, so as to suppress the stress accumulation and cracking of the metal part.

[0054] During printing, the pushing speed of the two pushing structures is usually determined by dividing the compressed length and time of the core substrate 9 when no pushing is performed, and this speed can be adjusted in real time according to the printing situation.

[0055] Furthermore, the propulsion force of the propulsion structure during the printing process is determined according to the friction force exerted on the core substrate when the molded part cools and shrinks during the printing process. During the propulsion process, if the propulsion structure 3 receives resistance from both sides of the core substrate, the propulsion force needs to be reduced in a timely manner to ensure that the speed of the propulsion structure 3 is stable and controllable.

[0056] The following is further described with reference to specific embodiments.

[0057] Example

[0058] To facilitate a deeper understanding of the present invention for those skilled in the art, the following detailed description of the present invention's technical solutions is provided in conjunction with the accompanying drawings. Using laser direct energy deposition (LDED) technology as a representative form of high-energy beam additive manufacturing (HEBM), and using a typical metal part as an example, the present invention demonstrates how the in-situ deformation control device effectively suppresses part cracking during metal additive manufacturing. To demonstrate the technical benefits of the present invention, the IN738LC nickel-based superalloy, a typical crack-prone material, is used as an example.

[0059] First, prepare two steel substrates, marked as R, with dimensions of 200 × 28 × 20 mm³ (see Figure 1 ).according to Figure 2 Machining was performed to obtain two designed substrates, designated as substrates DR. One DR substrate was used directly for 3D printing of IN738LC nickel-based superalloy parts, while the other DR substrate was used in conjunction with an in-situ deformation control device for 3D printing of IN738LC nickel-based superalloy parts.

[0060] Both working conditions use laser coaxial powder feeding direct energy deposition technology. The process conditions are 10,000-watt fiber laser (wavelength 960-1200 nm), laser power 4500 W, scanning speed 15 mm / s, layer lift 0.35 mm, and spot diameter 5.0 mm.

[0061] Using a DR substrate to directly deposit IN738LC nickel-based high-temperature alloy, the printed parts are as follows Figure 3 As shown, it can be seen that there is still a vertical crack in the center of the sample, which passes through multiple layers of deposition, mainly caused by excessive internal stress accumulation during the printing process.

[0062] In order to control the cracking of parts during the additive manufacturing process of IN738, an in-situ deformation control device was designed, such as Figure 4 shown. Figure 5 The designed substrate is shown to be assembled into an in-situ deformation control device. Figure 6 During the 3D printing process, the in-situ deformation control device squeezes the R3 portion of the DR substrate in real time, compressing it along the scanning direction. Since tensile stress primarily lies along the scanning direction, compressing the R3 portion of the DR substrate converts tensile stress in the deposited layer into compressive stress, significantly reducing the risk of cracking.

[0063] By using the in-situ deformation control device, 200 layers of deposition layers were 3D printed, and finally the successful printing of a crack-free IN738 part with a size of 180x60x10 mm3 was achieved, as shown in Figure 7 .

[0064] The application discloses an in-situ control device and method for inhibiting cracking of metal additive manufacturing, which comprises two pushing structures arranged on both sides of a core substrate which has been provided with a transverse gap, and the two pushing structures are in contact with the core substrate from both sides of the core substrate, so that the two pushing structures assist in extruding the shrinkage of the core substrate from both sides of the core substrate during the additive manufacturing process, and the shrinkage speed of the core substrate can match the required shrinkage speed of the formed part. The device of the application is an in-situ device for regulating local structure deformation of the substrate, which regulates the local deformation of the substrate in real time during the additive manufacturing process, thereby adjusting the distribution and evolution of the stress field, successfully converting tensile stress into compressive stress, and effectively inhibiting the generation and expansion of cracks.

[0065] In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the features defined as "first" and "second" can explicitly or implicitly include one or more of the features. In the description of the present application, "a plurality of" means two or more, unless otherwise specified. In the description of the present application, the "above" or "below" of the first feature to the second feature can include that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact through another feature therebetween.

[0066] In the description of the present application, the "above", "over" and "on" of the first feature to the second feature include that the first feature is directly above and obliquely above the second feature, or only means that the first feature is higher in horizontal height than the second feature.

[0067] In the description of the application, it is necessary to point out that, unless otherwise explicitly specified and limited, the terms "mounting", "connection", "linking" should be understood broadly, for example, can be fixed connection, can also be detachable connection, or integrally connected; can be mechanical connection, can also be electrical connection; can be directly connected, can also be indirectly connected through intermediate medium, can be internal communication of two elements. For those skilled in the art, the specific meaning of the above terms in the application can be understood according to the specific circumstances.

[0068] In the description of the present application, the description of the terms "one embodiment", "some embodiments", "exemplary embodiment", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present application, the exemplary description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0069] Although the embodiments of the present application have been shown and described, those skilled in the art can understand that various changes, modifications, replacements and variations can be made to the embodiments without departing from the principles and purposes of the present application, and the scope of the present application is defined by the claims and their equivalents.

[0070] The above is only the preferred embodiment of the present application, and does not limit the present application, any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. An in-situ control device for suppressing cracking in metal additive manufacturing, characterized in that: include: A base (8) is provided, wherein two suspensions (4) are slidably connected to the base (8), and the two suspensions (4) are arranged transversely along the base (8); a propulsion structure (3) is respectively provided at the opposite ends of the two suspensions (4), and the two propulsion structures (3) are arranged at the two longitudinal ends of the core substrate (9), respectively abutting against the two sides of the core substrate (9), and the two propulsion structures (3) and the core substrate (9) are coaxial; a transverse gap is provided on the core substrate (9); a top plate (2) is provided below the suspension (4), and the top plate (2) abuts against the two longitudinal ends of the substrate, and the core substrate (9) is provided in the substrate (5), and the core substrate (9) can move longitudinally relative to the substrate (5).

2. The in-situ control device for suppressing cracking in metal additive manufacturing according to claim 1, characterized in that: The base (8) is connected to the suspension (4) via the guide rail (6), and both ends of each suspension (4) are slidably connected to a guide rail (6) respectively.

3. The in-situ control device for suppressing cracking in metal additive manufacturing according to claim 2, characterized in that: A motor (1) is provided on the base (8), and the motor (1) is used to drive the two ends of the suspension (4) to move relative to the guide rail (6).

4. The in-situ control device for suppressing cracking in metal additive manufacturing according to claim 2, characterized in that: The guide rail (6) is a lead screw structure, and both ends of the suspension (4) are slider structures.

5. The in-situ control device for suppressing cracking in metal additive manufacturing according to claim 2, characterized in that: An upper panel (7) is provided on the base (8), and the upper panel (7) is fixed to the base (8) via a bracket. A slot for placing the guide rail (6) is provided on the upper panel (7).

6. The in-situ control device for suppressing cracking in metal additive manufacturing according to claim 1, characterized in that: The propulsion structure (3) is in the shape of a thimble, a block or a cylinder.

7. The in-situ control device for suppressing cracking in metal additive manufacturing according to claim 1, characterized in that: The propulsion structure (3) is in the shape of a thimble.

8. An in-situ control method for suppressing cracking in metal additive manufacturing based on the in-situ control device according to claim 1, characterized in that: During the additive manufacturing melt deposition process, two propulsion structures (3) propel the core substrate (9) from both sides of the core substrate (9).

9. The in-situ control method for suppressing cracking in metal additive manufacturing according to claim 8, characterized in that: The propulsion speed of the propulsion structure is determined according to the contraction speed of the core substrate (9).

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