Method and device for manufacturing self-reinforced steel parts based on ded metal printing technology

Abstract

The application discloses a preparation method and equipment of a self-reinforced steel piece based on a DED metal printing technology, and relates to the technical field of metal additive manufacturing. The method comprises the following steps: based on the stress of the steel piece under a preset service working condition, a three-dimensional topological distribution path of an endogenous geometric thickening reinforcement belt in the steel piece is constructed; for the three-dimensional topological distribution path, printing parameters of a directional energy deposition (DED) are set, wherein the printing parameters comprise printing material reinforcement thickening parameters; and based on the printing parameters, the steel piece is printed along the three-dimensional topological distribution path. The application improves the integrated preparation level of the service period bearing and deformation resistance of the steel component.

Description

Technical Field

[0001] This invention relates to the field of metal additive manufacturing technology, specifically to a method and equipment for preparing self-reinforcing steel parts based on DED metal printing technology. Background Technology

[0002] Steel structural members (including but not limited to H-beams, I-beams, channel steel, angle steel, T-beams, and open or closed square / round tubular profiles) are widely used in engineering structures, equipment load-bearing frames, racks, and support components. Directed Energy Deposition (DED) technology, with its advantages of high forming efficiency and high material utilization, has shown great application potential in the rapid manufacturing and in-situ repair of large metal components (such as load-bearing steel sections and thin-walled structural members). However, facing the increasingly demanding requirements of modern industry for high strength, toughness, lightweight, and deformation resistance in steel structural members, existing technologies have revealed significant shortcomings in the following three aspects.

[0003] 1) Insufficient strengthening methods: The commonly used stacking strategy of uniform wall thickness / uniform channel width makes it difficult to form controlled reinforcement or constraint in high stress areas, thus limiting the overall strength, stiffness and fatigue resistance.

[0004] 2) Stress concentration and instability risk: Thin-walled steel is prone to local buckling or crack initiation under bending, torsion, and local buckling conditions; the lack of "self-restraint" structure will amplify deformation.

[0005] 3) Traditional secondary strengthening methods compromise the integrity of components and easily introduce fatigue sources: Traditional secondary processing strengthening methods not only increase manufacturing processes and costs, but also damage the metallurgical integrity of steel components. External welding inevitably introduces secondary heat-affected zones and severe geometric stress concentration points. These weak points are very likely to become the initiation sites of fatigue cracks under complex alternating loads, leading to premature component failure. Summary of the Invention

[0006] This invention addresses the problem of insufficient load-bearing and deformation resistance during service life in traditional steel component manufacturing technologies by providing a method and equipment for preparing self-reinforcing steel components based on DED metal printing technology, thereby improving the integrated preparation level of load-bearing and deformation resistance during service life of steel components.

[0007] The present invention is achieved through the following technical solution.

[0008] In a first aspect, a method for preparing self-reinforcing steel parts based on DED metal printing technology is provided, the method comprising:

[0009] Based on the stress of the steel profile under the preset service conditions, a three-dimensional topological distribution path of the endogenous geometric thickening and strengthening band inside the steel profile is constructed.

[0010] For the three-dimensional topological distribution path, printing parameters for directional energy deposition (DED) are set, wherein the printing parameters include printing material reinforcement and thickening parameters;

[0011] Based on the printing parameters, the steel profile is printed along the three-dimensional topological distribution path.

[0012] In some embodiments, based on the stress on the steel section under preset service conditions, a three-dimensional topological distribution path of the endogenous geometric thickening and strengthening bands is constructed within the steel section, including:

[0013] A stress model is established based on the stress on the steel components under preset service conditions.

[0014] Based on the stress model, the three-dimensional topological distribution path of the required endogenous geometric thickening and strengthening band inside the steel section is derived in reverse.

[0015] In some embodiments, for the three-dimensional topology distribution path, the printing parameters of the DED are set, including:

[0016] For each layer to be printed, set the circumferential spacing / pitch or number of reinforcing strips, at least one start point and one end point in each layer, and the offset method of the start point. The offset method includes offset by arc length and offset by phase angle, and the thickness of adjacent layers in each layer is different.

[0017] In some embodiments, printing the steel profile along the three-dimensional topological distribution path based on the printing parameters includes:

[0018] Along the three-dimensional topological distribution path, based on at least one starting point and corresponding ending point of each layer to be printed, DED (Digital Evolution of Printed Material) is performed from the starting point to the closed path to the ending point until the thickness requirement is met. The printing material is thickened and strengthened by a predetermined short distance or a predetermined short time before and after the starting point.

[0019] In some embodiments, for the three-dimensional topology distribution path, the printing parameters of the DED are set, including:

[0020] Based on the three-dimensional topological distribution path, standard deposition zones and dynamic thickening zones are defined on a one-dimensional continuous path;

[0021] Establish a coupled response model between local thickness increase and process parameters;

[0022] Based on the thickness of the standard deposition zone, the baseline process parameters are calculated;

[0023] Based on the increase in thickness of the dynamically thickened zone relative to the thickness of the standard deposition zone and the coupled response model, the enhancement process parameters are calculated.

[0024] In some embodiments, printing the steel profile along the three-dimensional topological distribution path based on the printing parameters includes:

[0025] The steel profile is continuously printed along the three-dimensional topological distribution path, wherein the process parameters are dynamically switched when switching between the standard deposition area and the dynamic thickening area.

[0026] In some embodiments, a thickness ramp is provided at a predetermined distance at the boundary between the standard deposition zone and the dynamic thickening zone for transition, wherein the thickness ramp is achieved by smoothly changing the printing material enhancement and thickening parameters.

[0027] In some embodiments, linear interpolation or polynomial interpolation is used to change the printing material enhancement and thickening parameters.

[0028] In some embodiments, the printing material enhancement and thickening parameters include at least one of the following:

[0029] Reduce scanning speed;

[0030] Increase powder feeding rate and improve laser power;

[0031] Increase the residence time of the light spot;

[0032] Increase high-frequency pulse energy;

[0033] Increase the overlap rate of local scan paths.

[0034] Secondly, a fabrication apparatus for self-reinforcing steel parts based on DED metal printing technology is provided, for implementing the method described in any of the above-mentioned embodiments, the apparatus comprising:

[0035] The gas supply unit is used to provide protective gas to the deposition area to ensure the quality of the deposition.

[0036] The six-axis robotic arm unit is used to drive the print head to move along a preset path to perform directional energy deposition printing;

[0037] The positioner unit is used to carry the workpiece to be printed and adjust its posture to cooperate with the robotic arm to complete the printing process;

[0038] The control cabinet unit is used to coordinate the control of the six-axis robot arm unit, the positioner unit and the gas supply unit, and to control the printing process according to preset process parameters;

[0039] An end effector unit, located at the end of the robotic arm, is used to complete the deposition of printing powder material.

[0040] Compared with the prior art, the present invention has the following advantages and beneficial effects.

[0041] 1) It solves the problem of the lack of endogenous deformation constraint mechanism in existing uniform thickness components during service life.

[0042] By actively constructing "local geometric thickening and strengthening bands" arranged in three-dimensional space during the printing process, a high-rigidity implicit skeleton is generated in situ inside the steel component. This skeleton can form a "self-constraining" mechanical environment from the inside to resist and limit deformation during the service of the component, thereby essentially realizing the "self-reinforcement" of the component's macroscopic load-bearing capacity.

[0043] 2) It solves the problems of traditional external secondary strengthening methods damaging the integrity of components and easily causing stress concentration.

[0044] By utilizing the deposition characteristics of the DED process itself (i.e., the synergistic control of deposition path and process parameters), the synchronous "growth" of the reinforcing band and the component matrix can be achieved in a single material system. This completely eliminates interface metallurgical defects, secondary thermal damage and severe geometric stress concentration points caused by external welding, realizing true integrated fabrication of structure and function and significantly improving the fatigue life of the component.

[0045] 3) It solves the problem of uncontrollable enhanced feature morphology and difficulty in accurately matching it with structural mechanics requirements.

[0046] A novel process control strategy (including the spatial arrangement of the phases at the start and end points of the path and the dynamic modulation of process parameters in specific sections) is proposed, which enables the thickness, orientation and distribution density of the internal thickening and strengthening strip to be strictly customized according to the stress distribution (such as bending moment diagram and shear force diagram) of the steel section during service, so as to achieve precise adaptation between complex mechanical requirements and additive manufacturing process. Attached Figure Description

[0047] To more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0048] Figure 1 This is a flowchart illustrating a method for preparing a self-reinforcing steel part based on DED metal printing technology according to an embodiment of the present invention. Figure 2 This is a physical image of a self-reinforcing steel part based on DED metal printing technology according to an embodiment of the present invention.

[0049] Figure 3 This is an example diagram of the constraint band form according to an embodiment of the present invention. Detailed Implementation

[0050] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments and accompanying drawings. The illustrative embodiments and descriptions of the present invention are only used to explain the present invention and are not intended to limit the present invention.

[0051] To address the problem of insufficient load-bearing and deformation resistance during service life in traditional steel component manufacturing technologies, this invention provides a preparation scheme for self-reinforcing steel components based on DED metal printing technology. This scheme breaks away from the traditional mindset of "homogeneous and uniform thickness" printing, and actively and controllably integrates geometric strengthening features in situ during the steel component preparation process. Under a single material system, by utilizing the inherent characteristics of the printing process, a high-rigidity implicit skeleton is directly "grown" in situ inside the component, thereby achieving an integrated improvement in the structural and functional aspects of the steel component.

[0052] On one hand, this invention provides a method for fabricating a self-reinforcing steel component based on DED metal printing technology. This method includes: constructing a three-dimensional topological distribution path of an endogenous geometric thickening reinforcement band within the steel component based on the stress on the steel component under preset service conditions; setting printing parameters for directional energy deposition (DED) for the three-dimensional topological distribution path, wherein the printing parameters include printing material reinforcement parameters; and printing the steel component along the three-dimensional topological distribution path based on the printing parameters.

[0053] Figure 1 This is a flowchart illustrating a method for fabricating a self-reinforcing steel part based on DED metal printing technology according to an embodiment of the present invention. (Reference) Figure 1 The method for preparing a self-reinforcing steel part based on DED metal printing technology includes: S11 to S16.

[0054] In S10,

[0055] Based on the stress model of the steel component under preset service conditions (such as principal stress trajectories, maximum bending moment zone, or high shear zone), the three-dimensional topological distribution path of the required "endogenous geometric thickening strengthening zone" inside the component is derived in reverse. The steel component can be an open section (H / I / U / T / angle steel, etc.) or a closed section (square tube, rectangular tube, round tube, etc.), and can be a straight or curved spatial profile.

[0056] Specifically, in S11, the geometric model, material parameters, and preset service conditions of the steel component are obtained; in S12, the stress analysis of the steel component is performed based on the preset service conditions; in S13, the reinforcement requirement area of ​​the steel component is determined based on the stress analysis results; and in S14, the three-dimensional topological distribution path of the endogenous geometric reinforcement band inside the steel component is constructed based on the reinforcement requirement area.

[0057] In S15, directional energy deposition (DED) printing parameters are set for the three-dimensional topology distribution path, and the printing path is generated based on the printing parameters.

[0058] DED reinforcement tape (constraint tape) printing can be divided into intermittent / start-stop thickening tape printing controlled by the starting phase and continuous speed / powder feeding modulation tape printing triggered by path parameters.

[0059] The intermittent / start-stop thickening strip formation with start-point phase control breaks through the random start-end point or alternating staggered start-end point rules used in traditional DED processes to pursue flatness. Through precise path space mapping, it actively utilizes the acceleration transient physical effect at the start point to construct a continuous endogenous reinforcing skeleton in the target area. Its DED printing parameters include: setting the circumferential spacing / pitch or number of strips for each layer to be printed, at least one start and end point in each layer, and the offset method of the start point. The offset method includes offset by arc length and offset by phase angle, and the thickness of adjacent layers in each layer is different.

[0060] Specifically, given the "circumferential spacing / pitch" or "number of bands" parameters of the target constraint bands, the offset of the starting point of the k-th layer relative to the (k-1)-th layer is set, expressed as an arc length offset: the starting point advances δ along the path sk ; or expressed as phase angle offset: δ θk (Applicable to sections that are approximately circular or whose circumferential parameters can be calculated).

[0061] Example patterns (choose one or a combination):

[0062] Equal step offset forms a spiral band: δ sk =s0 (constant), which makes the starting point advance evenly in the circumferential direction to form a spiral.

[0063] Multi-band parallel processing: Mapping layer number k to multiple phase sets, enabling the simultaneous generation of multiple spiral / ring bands.

[0064] The path parameter-triggered continuous velocity / powder feeding modulation breaks the traditional homogeneous deposition mode of "maintaining constant parameters within a single pass" in the DED process. For components that need to be printed in one step, it actively and dynamically changes the coupling relationship of multiple variables such as laser power, scanning speed, and powder feeding rate to achieve precise geometric thickening of specified sections. Its printing parameters for Directional Energy Deposition (DED) include: defining a standard deposition zone and a dynamic thickening zone on a one-dimensional continuous path based on a three-dimensional topological distribution path; establishing a coupling response model between local thickening amount and process parameters; calculating baseline process parameters based on the thickness and coupling response model of the standard deposition zone; and calculating strengthening process parameters based on the thickness and coupling response model of the dynamic thickening zone.

[0065] Specifically, when generating the continuous scanning path for the Nth layer, project the cross-section of the reinforcement band on this layer onto the corresponding scanning line segment to define the alternating intervals of the standard deposition area and the dynamic thickening area on the continuous path; establish a coupling response model between the local thickening amount Δh and process parameters (e.g., scanning speed v, laser power P, powder feeding rate f), and set one or more sets of parameter modulation gain groups (reinforcement process parameters); in the standard deposition area, execute the reference process parameter combination (v0, P0, f0) to form the reference layer thickness h0, and in the dynamic thickening area, execute the reinforcement process parameter combination. Specific reinforcement process parameter strategies include, but are not limited to:

[0066] (1) Deceleration thickening mode: Reduce the scanning speed (v R < v0), increasing the material accumulation amount and line energy input per unit time;

[0067] (2) Powder feeding increase thickening mode: While maintaining or slightly adjusting the speed, increase the powder feeding rate (f R > f0) and synchronously increase the laser power (P R > P0) to ensure that the newly added powder is completely melted and good interlayer metallurgical bonding is achieved. Through parameter coupling, make the deposited layer thickness h R significantly greater than h0.

[0068] In S16, print the profiled steel part along the three-dimensional topological distribution path.

[0069] For the discontinuous / start-stop thickening into a band with starting point phase control, along the three-dimensional topological distribution path, based on at least one starting point and the corresponding end point of each layer to be printed, respectively execute the DED of starting point - closed path - end point until the thickness requirement is met.

[0070] Specifically, the DED robotic arm prints the kth layer according to the planned path and executes the deposition of "starting point - closed path - end point"; near the starting point of each layer, the following at least one thickening enhancement measure can be superimposed (for improving controllability rather than relying on natural fluctuations): short-distance deceleration segments before / after the starting point (e.g., the speed drops from v0 to vs within the length of ls after the starting point), short-time powder feeding / wire feeding leading or delayed shut-off at the starting point (forming material enrichment), short-time power gain or maintenance at the starting point (forming a larger molten pool and higher accumulation), etc., until the target thickness is reached.

[0071] For example, the recommended range of controllable parameters can be set as follows: layer height h: 0.4 - 1.5 mm, conventional speed v0: 6 - 20 mm / s, starting point enhanced speed vs: 0.4v0 - 0.8v0, starting point enhanced segment length ls: 2 - 30 mm, starting point interlayer offset δsk: 0 - 20 mm (related to the perimeter and band spacing).

[0072] The path code is written according to the above method to drive the DED device to perform continuous printing. The excess molten metal pools at the start and end points of each layer are precisely overlapped at predetermined positions; relying on the high temperature heat input of subsequent layers, these discrete geometric thickening areas are not only connected into continuous or quasi-continuous constraint bands in physical space, but also achieve complete metallurgical bonding with the surrounding standard thickness area in microstructure, ultimately growing a high-rigidity implicit skeleton in situ inside the steel component.

[0073] For continuous speed / powder feeding modulation tape triggered by path parameters, steel parts can be continuously printed along a three-dimensional topology distribution path. When switching between the standard deposition zone and the dynamic thickening zone, the process parameters are dynamically switched.

[0074] To avoid melt pool instability, splashing, or microstructural defects (such as porosity or lack of fusion) caused by parameter abrupt changes at the boundary between the standard deposition zone and the dynamic thickening zone, a "slope transition" strategy using linear or polynomial interpolation is adopted when switching parameters.

[0075] Within the predetermined distance of entering and exiting the thickened zone (transition zone L) t A thickness ramp is set to facilitate the transition. This thickness ramp is achieved by smoothly changing the parameters (scanning speed, power, and powder feed rate, etc.) that enhance the thickness of the printed material. This smooth transition not only ensures the continuity of the macroscopic geometry but also effectively mitigates abrupt changes in local thermal stress at the interface, preventing the initiation of microcracks at the edges of the endogenous strengthening zone.

[0076] Repeated printing precisely aligns and overlaps the "dynamically thickened areas" of adjacent layers. Due to the greater heat capacity and heat input of the thickened areas, these regions generate a different cooling contraction rate than the surrounding homogeneous areas during the layer-by-layer stacking process, thereby actively inducing a residual compressive stress field that is beneficial for resisting external loads. Ultimately, a "customized" continuous solid reinforcement network with high stiffness and fatigue resistance is grown in situ inside the steel structure.

[0077] In some embodiments, the parameters for enhancing and thickening the printing material include at least one of the following: reducing the scanning speed; increasing the powder feed rate and increasing the laser power; increasing the spot dwell time; increasing the high-frequency pulse energy; and increasing the local scanning path overlap rate. By setting and changing the above parameters, the enhancement and thickening of the printing material can be achieved. (Reference) Figure 2 The image shown is a physical drawing of a self-reinforcing steel component. (Reference) Figure 3 The diagram shows three examples of constraint band forms: (a), (b), and (c).

[0078] The following technical effects can be achieved through the above-described technical solution of the present invention.

[0079] 1) In-situ construction of an endogenous framework enables "self-reinforcing" macroscopic mechanics during service life.

[0080] Breaking away from the conventional homogeneous and uniform thickness printing, this method reorganizes the spatial phase of the start and end points during the printing process and dynamically modulates multiple process parameters (speed, powder feed rate, power) in continuous operation sections to precisely construct "local geometric thickening and strengthening zones" distributed along the stress path within the steel structure. This inherent high-rigidity implicit skeleton enables the component to effectively limit local instability and excessive deformation when subjected to complex external loads (such as bending moment and shear force) during service, thereby significantly improving the macroscopic load-bearing capacity and deformation stiffness of the component without increasing the overall structural weight.

[0081] 2) External connection defects were eliminated, achieving structural-functional integration and high fatigue life.

[0082] Unlike traditional methods that involve secondary welding of external reinforcing ribs / plates after printing, this invention utilizes the characteristics of DED (Dual Engraving and Deposition) technology to allow the reinforcing band and the component matrix to grow synchronously in situ within the same pass and material system. This preparation method ensures complete metallurgical bonding and a continuous microstructure between the thickened reinforcing zone and the standard thickness zone, completely eliminating the secondary heat-affected zone (HAZ), interface bonding defects, and severe geometric stress concentration points caused by external welding. Therefore, the integrity of the component is perfectly preserved, significantly reducing the risk of fatigue crack initiation under alternating loads during service life and substantially extending the component's service life.

[0083] 3) Utilizing thermophysical differences to induce beneficial stress fields, forming a "self-constraining" mechanism to resist deformation.

[0084] This invention, when constructing a locally thickened strengthening zone, establishes a smooth transition zone (sloping transition) for process parameters and utilizes the natural physical differences in heat input and cooling contraction rates between the thickened zone and the surrounding standard zone to actively induce a localized residual compressive stress field distributed around the strengthening zone within the steel component. When the component is subjected to tension during service, this pre-set residual compressive stress can offset some of the external working tensile stress, forming an inherent mechanical "self-constraint" environment. This not only effectively suppresses macroscopic warping of the component but also inhibits the propagation of potential microcracks (crack arrest effect).

[0085] 4) Fully utilize the inherent characteristics of the process to achieve low-cost, on-demand structural customization.

[0086] This invention transforms the inherent "transient deposition increment" physical characteristic in the initial stage of the DED process into a continuous macroscopic geometrically reinforced structure through spatial slicing and discretization. This strategy not only eliminates the need for complex control algorithms and subsequent subtractive processing costs to mitigate this transient effect, but also grants the fabrication process extremely high design and manufacturing freedom. Designers do not need to manufacture special tooling; they only need to strictly design the reinforcement band form according to the stress model of the component to accurately construct various forms of endogenous reinforcement networks within the component at low cost, achieving a highly efficient closed-loop adaptation between structural mechanics requirements and additive manufacturing processes.

[0087] The technical solution of the present invention will be described below through specific application examples.

[0088] Example 1: Preparation of a thin-walled hollow round tube of 316L stainless steel with internal spiral reinforcing band

[0089] A 100mm diameter 316L stainless steel thin-walled hollow cylindrical tube was fabricated using a robotic arm and a coaxial powder-feed laser-directed energy deposition (DED) system, intended for use in complex stress environments. To enhance its resistance to local buckling, this embodiment employs a layer-by-layer printing process to construct a spiral-shaped geometric thickening reinforcement band in situ within its thin wall. The specific implementation steps are as follows.

[0090] Step 1: Calibration of basic process parameters and transient characteristics

[0091] 1) Materials and equipment: 316L stainless steel powder with a particle size of 45~105umm is used; the substrate is 304 stainless steel plate; the protective gas is argon; the energy source is laser, and the photo-powder coaxial method is adopted.

[0092] 2) Calibration reference parameters: Set the laser power P = 1300W, scanning speed v0 = 12mm / s, powder feed rate f0 = 1.2 rad / min, and spot diameter to 4mm for the standard linear scanning section. Under these parameters, the standard deposition thickness h0 of a single layer is approximately 0.8mm, and the melt width is approximately 1.8mm.

[0093] 3) Calibration of transient characteristics: Through single-pass testing, when the laser head accelerates from rest to v0, the maximum local melt width of the "transient deposition increment" at the starting point due to acceleration is about 2.4 mm, and the transient deposition influence length L is about 6.0 mm.

[0094] Step 2: Constructing the spiral-strengthened spatial phase (building a spiral-strengthened constraint band)

[0095] 1) Setting the starting point offset and lifting parameters: The starting point of each layer is offset by 3mm along the circumferential arc length, and the Z-axis of the robotic arm is lifted by 0.8mm for each layer.

[0096] 2) Programming: Based on the offset and lifting amount of each layer, take the starting point of printing the first layer as the origin of the coordinate system, obtain the spatial coordinates of the starting point of each layer, and compile the robotic arm running program based on these coordinates.

[0097] 3) Layer-by-layer printing: As the number of layers increases, the "transient deposition increment" at the starting point of each layer precisely overlaps in a stepped manner in space, and a spiral geometric thickening band grows in situ inside the circular tube wall.

[0098] Example 2: Preparation of a thin-walled hollow cylindrical tube made of 316L stainless steel with internal mesh reinforcement bands

[0099] A 100mm diameter 316L stainless steel thin-walled hollow cylindrical tube was fabricated using a robotic arm and a coaxial powder-feed laser-directed energy deposition (DED) system, intended for use in complex stress environments. To enhance its resistance to local buckling, this embodiment employed continuous printing to construct a "mesh-like" geometric thickening reinforcement band in situ within its thin wall. The specific implementation steps are as follows.

[0100] Step 1: Calibration of basic process parameters and strengthening zone parameters

[0101] 1) Materials and equipment: 316L stainless steel powder with a particle size of 45~105umm is used; the substrate is 304 stainless steel plate; the protective gas is argon; the energy source is laser, and the photo-powder coaxial method is adopted.

[0102] 2) Calibration reference parameters: Set the laser power P = 1300W, scanning speed v0 = 12mm / s, powder feed rate f0 = 1.2 rad / min, and spot diameter to 4mm for the standard linear scanning section. Under these parameters, the standard deposition thickness h0 of a single layer is approximately 0.8mm, and the melt width is approximately 1.8mm.

[0103] 3) Calibrate the parameters of the enhancement zone: The laser power of the enhancement zone is P=1600W, the scanning speed is v0=8 mm / s, the powder feed rate is f0=1.6 rad / min, and the spot diameter is 4mm. Under these parameters, the deposition thickness h1 of the enhancement zone is approximately 1.8 mm, the melt width is approximately 3 mm, and the corresponding arc length L of the enhancement zone is approximately 8.0 mm. A transition zone with an arc length of 4.0 mm is set on both sides of the enhancement zone. The laser power of the transition zone is P=1450W, the scanning speed is v0=12 mm / s, the powder feed rate is f0=1.6 rad / min, and the spot diameter is 4mm.

[0104] Step 2: Construction of the spatial phase of the mesh reinforcement (construction of mesh reinforcement constraint bands)

[0105] 1) Printing method and interlayer reinforcement strip overlap setting: The laser is always on during the printing of the round tube, and the robotic arm moves in a spiral upward motion, gradually rising until the printing reaches the specified height. The reinforcement strips (including transition sections) between layers overlap by 8mm.

[0106] 2) Programming: Based on the offset and lifting of each layer, and taking the printing start point as the coordinate origin, the spatial coordinates of the points where parameters need to change during the spiral printing process are obtained, and the robotic arm running program is compiled based on these coordinates.

[0107] 3) Spiral printing: As the specimen is spirally printed, the "deposition increment" caused by the change in process parameters overlaps in the tube wall to form a spatial network reinforcement band.

[0108] On the other hand, this invention provides a fabrication apparatus for self-reinforcing steel parts based on DED metal printing technology. This apparatus includes a gas supply unit for providing protective gas to the deposition area to ensure forming quality; a six-axis robotic arm unit for driving the print head along a preset path to perform directional energy deposition printing; a positioner unit for carrying the workpiece to be printed and adjusting its posture to cooperate with the robotic arm in completing the printing; a control cabinet unit for coordinating the control of the six-axis robotic arm unit, the positioner unit, and the gas supply unit, and controlling the printing process according to preset process parameters; and an end effector unit located at the end of the robotic arm for depositing the printing powder material. This fabrication apparatus allows for the fabrication of steel parts using the aforementioned method for self-reinforcing steel parts based on DED metal printing technology.

[0109] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing self-reinforcing steel parts based on DED metal printing technology, characterized in that, The method includes: Based on the stress of the steel profile under the preset service conditions, a three-dimensional topological distribution path of the endogenous geometric thickening and strengthening band inside the steel profile is constructed. For the three-dimensional topological distribution path, printing parameters for directional energy deposition (DED) are set, wherein the printing parameters include printing material reinforcement and thickening parameters; Based on the printing parameters, the steel profile is printed along the three-dimensional topological distribution path.

2. The method according to claim 1, characterized in that, Based on the stress of the steel section under preset service conditions, a three-dimensional topological distribution path of the endogenous geometric thickening and strengthening bands inside the steel section is constructed, including: A stress model is established based on the stress on the steel components under preset service conditions. Based on the stress model, the three-dimensional topological distribution path of the required endogenous geometric thickening and strengthening band inside the steel section is derived in reverse.

3. The method according to claim 1, characterized in that, For the aforementioned 3D topology distribution path, set the printing parameters for the DED, including: For each layer to be printed, set the circumferential spacing / pitch or number of reinforcing strips, at least one start point and one end point in each layer, and the offset method of the start point. The offset method includes offset by arc length and offset by phase angle, and the thickness of adjacent layers in each layer is different.

4. The method according to claim 3, characterized in that, Based on the printing parameters, the steel section is printed along the three-dimensional topological distribution path, including: Along the three-dimensional topological distribution path, based on at least one starting point and corresponding ending point of each layer to be printed, DED (Digital Evolution of Printed Material) is performed from the starting point to the closed path to the ending point until the thickness requirement is met. The printing material is thickened and strengthened by a predetermined short distance or a predetermined short time before and after the starting point.

5. The method according to claim 1, characterized in that, For the aforementioned 3D topology distribution path, set the printing parameters for the DED, including: Based on the three-dimensional topological distribution path, standard deposition zones and dynamic thickening zones are defined on a one-dimensional continuous path; Establish a coupled response model between local thickness increase and process parameters; Based on the thickness of the standard deposition zone, the baseline process parameters are calculated; Based on the increase in thickness of the dynamically thickened zone relative to the thickness of the standard deposition zone and the coupled response model, the enhancement process parameters are calculated.

6. The method according to claim 5, characterized in that, Based on the printing parameters, the steel section is printed along the three-dimensional topological distribution path, including: The steel profile is continuously printed along the three-dimensional topological distribution path, wherein the process parameters are dynamically switched when switching between the standard deposition area and the dynamic thickening area.

7. The method according to claim 6, characterized in that, A thickness slope is set at a predetermined distance at the boundary between the standard deposition zone and the dynamic thickening zone to facilitate transition, wherein the thickness slope is achieved by smoothly changing the thickening parameters of the printing material.

8. The method according to claim 7, characterized in that, The printing material's enhancement and thickness parameters can be changed using linear or polynomial interpolation.

9. The method according to claim 1, characterized in that, The printing material reinforcement and thickening parameters include at least one of the following: Reduce scanning speed; Increase powder feeding rate and improve laser power; Increase the residence time of the light spot; Increase high-frequency pulse energy; Increase the overlap rate of local scan paths.

10. A fabrication apparatus for self-reinforcing steel parts based on DED metal printing technology, used to implement the method according to any one of claims 1 to 9, characterized in that, The device includes: The gas supply unit is used to provide protective gas to the deposition area to ensure the quality of the deposition. The six-axis robotic arm unit is used to drive the print head to move along a preset path to perform directional energy deposition printing; The positioner unit is used to carry the workpiece to be printed and adjust its posture to cooperate with the robotic arm to complete the printing process; The control cabinet unit is used to coordinate the control of the six-axis robot arm unit, the positioner unit and the gas supply unit, and to control the printing process according to preset process parameters; An end effector unit, located at the end of the robotic arm, is used to complete the deposition of printing powder material.

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