A method for controlling deformation of large structural parts of an additive manufacturing gantry

Abstract

The application discloses a kind of methods for controlling deformation of large structure of additive preparation frame body, belong to additive manufacturing technical field.First, frame body structural component is split into several sub-components according to structure information, respectively additive several sub-components, then the sub-components after preliminary machining are connected as frame body structural component in isothermal zoning, and the whole structure is treated, size measurement, straightening, machining, and the stress detection and control of whole process are carried out.The application realizes the control of deformation of large structure of additive preparation frame body by the process of isothermal zoning connection, and carries out real-time detection and control of stress, realizes the control of deformation of large structure of additive preparation frame body, solves the problem of rapid additive manufacturing of existing frame body large structure, improves production efficiency and reduces production cost, both guarantees the mechanical properties of material, and effectively avoids the deformation of workpiece caused by integrated additive stress accumulation.

Description

TECHNICAL FIELD

[0001] The application relates to a method for controlling deformation of a large structure of an additive manufacturing frame body, and belongs to the technical field of additive manufacturing. BACKGROUND

[0002] The aerospace industry is a typical representative of the national high-end equipment manufacturing industry, and products thereof have the characteristics of complex structure, multiple processes and small batch. With the increasing complexity of aerospace typical components such as aircraft engines, large aircrafts and new generation launch vehicles and the continuous emergence of new materials, the structure of parts tends to be complex and large, and the traditional manufacturing method of combining casting, forging and mechanical processing will be difficult to meet the above manufacturing requirements. Additive manufacturing technology can well solve such problems, and metal additive manufacturing is a new technology that uses laser, electron beam or electric arc as a heat source to accumulate materials layer by layer according to three-dimensional model data, thereby realizing direct manufacturing of metal parts.

[0003] As a new manufacturing method, additive manufacturing has outstanding advantages in the manufacturing of high-performance large and difficult-to-machine metal components such as titanium alloy, high-temperature alloy and ultrahigh-strength steel. However, for large structures, due to the large size of the additive material, it is difficult to form integrally by existing equipment, and a large additive stress will be generated during the integral forming process, thereby causing deformation of the workpiece. In addition, for workpieces containing special structures, there are problems of difficulty in additive path planning and difficulty in processing, which limits the application of additive manufacturing in large-size and difficult-to-machine metal components.

[0004] To solve the above technical problems, domestic and foreign scholars have reported some exploratory research. For example, model optimization, zoned printing, and optimized additive path. Although such process means have certain effect of reducing stress and preventing deformation, but it is difficult to implement for some large-size structures with complex structure. Therefore, researchers have to explore some complex process methods with high cost. The additive and subtractive composite manufacturing equipment provided in patent CN 114474713 A can realize additive and subtractive manufacturing simultaneously through the same motion control system, effectively reducing the error generated in the additive and subtractive manufacturing process, but the performance requirements of the equipment are high and the operation is complex. The additive manufacturing deformation control scheme for large thin-walled structure parts designed in patent CN 114211001 A can shape the structure during the whole additive manufacturing process, avoiding the accumulation of internal stress and deformation to cause irreparable deformation, but it is not suitable for small batch structure parts, increasing the production cost. SUMMARY

[0005] The purpose of the present application is to overcome the defects of the prior art, and provide a method for controlling deformation of a large structure of an additive preparation frame body. The deformation of the large structure of the additive preparation frame body is controlled by the process of isothermal zonal connection, and real-time detection and regulation of stress, which solves the problem of rapid additive manufacturing of the large structure of the frame body, improves production efficiency and reduces production cost, ensures the mechanical properties of the material, effectively avoids the deformation of the workpiece caused by the stress accumulation of the integrated additive, and provides process guidance for the additive manufacturing of the large structure of the frame body.

[0006] To solve the above technical problems, the technical scheme adopted by the present application is:

[0007] A method for controlling deformation of a large structure of an additive preparation frame body, comprising the following steps:

[0008] S1: frame structure processing: based on the structure information of the frame structure, the frame model is optimized to obtain a plurality of sub-component models;

[0009] S2: additive manufacturing: using lungoPNT software to slice the optimized sub-component model, using different process parameters for additive manufacturing according to the number of slices, to obtain a plurality of sub-component blanks;

[0010] S3: stress relief treatment: stress relief treatment is performed on the plurality of sub-component blanks obtained by additive manufacturing;

[0011] S4: machining treatment: the plurality of sub-component blanks after stress relief treatment are preliminarily machined according to the size information to obtain a plurality of sub-components;

[0012] S5: isothermal zonal connection of sub-components: the plurality of machined sub-components are isothermally zonally connected into a frame structure according to the size requirements;

[0013] S6: workpiece heat treatment: the frame structure after isothermal zonal connection is subjected to heat treatment, and a heat treatment tooling is required before heat treatment;

[0014] S7: size measurement: the frame structure after heat treatment is subjected to size measurement according to the size requirements;

[0015] S8: straightening: the frame structure that does not meet the size requirements is straightened using a straightening tooling until the size requirements are met;

[0016] S9: finishing: the frame structure that meets the size measurement requirements is subjected to milling machine processing;

[0017] S10: stress detection and regulation: after the additive manufacturing, stress relief treatment, machining treatment, and isothermal zonal connection of the sub-components of the frame structure, the stress is detected and regulated according to the detection results.

[0018] Further, the rack structure member is a large size and complex structure.

[0019] The large size of the rack structure member refers to the overall size of about 2.5m in length, 1.5m in width, and 0.5m in height.

[0020] The complex structure refers to that the rack structure member includes a front rack, a rear rack, a cross beam, a left side beam, and a right side beam.

[0021] Further, the structure information includes a model, drawings, size requirements, and the like, including but not limited to. In the present application, the structure information includes the front rack, the rear rack, the cross beam, the left side beam, and the right side beam of the rack structure member.

[0022] Further, the optimization processing of the rack model includes:

[0023] S11: based on the structure information of the rack structure member, the rack model is divided into a plurality of sub-component models;

[0024] S12: the sub-component models after the division are subjected to structure optimization according to the requirements of the additive manufacturing process, including excess amount addition, corner processing, and the like.

[0025] Further, in step S2, the additive manufacturing is one of electric arc, electron beam, plasma, and laser additive manufacturing.

[0026] Further, the additive manufacturing is electric arc additive manufacturing, the additive voltage is 15V-25V, the additive current is 70A-100A, the wire feeding speed is 6m / min-12m / min, and the welding speed is 6mm / s-15mm / s.

[0027] Further, the additive manufacturing method adjusts different process parameters for additive manufacturing according to the number of layers of the software slicing, which is specifically divided into three parts:

[0028] S21: priming: the first layer additive current is 90-100A, the wire feeding speed is 10-12m / min, and other parameters remain unchanged;

[0029] S22: filling: the middle transition layer additive current is 80-90A, the wire feeding speed is 8-10m / min, and other parameters remain unchanged;

[0030] S23: finishing: the last layer additive current is 70-80A, the wire feeding speed is 6-8m / min, and other parameters remain unchanged.

[0031] Further, in step S3, the stress relief treatment includes the following: the additive manufacturing obtained sub-component blank is subjected to stress relief annealing, and the heat treatment parameters are as follows: the temperature is raised to 150-300 DEG C at a temperature rising rate of 50-100 DEG C / h, and then the temperature is kept for 2-6 h, and the workpiece is taken out of the furnace and air cooled to room temperature.

[0032] Further, in step S4, the machining information refers to surface machining of the area to be welded next by a milling machine, and fine machining of the area which is not easy to machine after welding according to the drawing.

[0033] Further, in step S5, the size requirement includes the drawing size and the workpiece size required by the technical agreement and the like.

[0034] Further, the isothermal zonal connection refers to heating the area to be connected to 150-300 DEG C by a ceramic heating sheet, and the specific connection mode is welding.

[0035] Further, the isothermal zonal connection includes the following three parts:

[0036] S51: Assembling the segmented sub-components according to the size requirement, and a welding shrinkage allowance should be left during the assembling;

[0037] S52: Fixing the workpiece along the direction perpendicular to the welding direction after the sub-components are assembled;

[0038] S53: Heating the sub-components fixed by the workpiece, and then welding in a certain order to obtain the target structure part.

[0039] Specifically, the frame structure part after the isothermal zonal connection is subjected to heat treatment, and the solution system is as follows: the temperature is raised to 400-800 DEG C at a temperature rising rate of 100-200 DEG C / h, and then the temperature is kept for 6-10 h, and then the workpiece is water cooled; the aging system is as follows: the temperature is raised to 150-300 DEG C at a temperature rising rate of 50-100 DEG C / h, and then the temperature is kept for 2-6 h, and then the workpiece is taken out of the furnace and air cooled to room temperature. The workpiece needs to be installed with a heat treatment workpiece before heat treatment, and the workpiece structure includes the following: an internal square tube for preventing the edge beam from shrinking inward, a long plate for preventing the edge beam from twisting upward and downward, a square tube for connecting various areas, and an external square tube for preventing the edge beam from deforming outward. The square tube is a hollow steel tube with a wall thickness of 10 mm, and the area where the internal square tube is connected to the workpiece needs to be isolated by an aluminum block.

[0040] Further, in step S7, the size measurement method is three-dimensional scanning, which specifically includes the following:

[0041] S71: Obtaining the scanning information of the frame structure part which has been subjected to heat treatment, including the external contour and the three-dimensional size;

[0042] S72: Determine the size information of the rack structure member which has completed heat treatment according to the scanning information of the rack structure member which has completed heat treatment, including length, width, height, angle, surface concave-convex degree, etc.

[0043] S73: Determine whether the size information of the rack structure member which has completed heat treatment matches the corresponding model information.

[0044] Further, in step S8, the straightening is one of mechanical straightening or heat straightening.

[0045] Further, in step S10, the stress detection method is electrochemical blind hole detection method, and the stress control method is stress relief heat treatment.

[0046] Further, the stress control according to the detection result is divided into the following five parts:

[0047] S101: Select the to-be-detected area and the punching point on the rack structure member, and install the strain gauge and the strain meter, and use the puncher to punch the to-be-detected area;

[0048] S102: After the value on the strain meter tends to be stable, substitute the strain value detected by the strain gauge into the formula:

[0049]

[0050] The main stress size of the rack structure member can be calculated, wherein σ max , σ min are two main stresses in the rack structure member; σ max is the maximum main stress, and σ min is the minimum main stress; the included angle of the three strain gauges is 120°; A and B are release coefficients of the strain gauges, and the values thereof are obtained according to experimental calibration, and respectively reflect the energy release proportion of the material after experiencing a strain and stress; the release strains detected by the three sensitive grids in the strain gauge are ε0, ε 120 and ε 240 .

[0051] S103: Then, the stress detection is performed on the rack structure member before stress relief (i.e., the rack structure member before stress relief treatment) and the rack structure member after stress relief, respectively, to obtain the maximum main stresses σ1 and σ2, and then the stress change rate δ1 during stress relief treatment is obtained according to the formula, as follows:

[0052]

[0053] S104: The stress detection is performed on the n-1th step and the nth step which need to be detected, to obtain σ n-1 and σ n , and then the stress change rate δn of the nth step is obtained according to the formula.n , the formula is as follows:

[0054]

[0055] S105: compare the stress change rate δn of the n th step with the stress change rate δ1 after the stress relief treatment, if δn≥δ1, stress relief heat treatment is needed, otherwise, it is not needed. n n ≥δ1, stress relief heat treatment is needed, otherwise, it is not needed.

[0056] The beneficial effects of the present application are as follows:

[0057] The present application considers that the stress accumulation caused by the integration of the rack body structure parts will lead to the deformation of the workpiece, through the process of isothermal zonal connection, and the real-time detection and control of stress, the control of the deformation of the rack body large structure part prepared by additive manufacturing is realized, the problem of rapid additive manufacturing of the existing rack body large structure part is solved, the production efficiency is improved and the production cost is reduced, the stress measurement and control at each stage can provide real-time stress data and stress relief treatment to prevent the accumulation of residual stress in the workpiece. The rack body large structure part additive manufacturing method provided by the present application can be applied to arc, electron beam, plasma, laser and other additive manufacturing.

[0058] The present application discloses a method for controlling the deformation of a rack body large structure part prepared by additive manufacturing, first, the rack body structure part is split into several sub-components according to the structure information, and then the sub-components are additive manufactured, then the sub-components after preliminary machining are connected into a rack body structure part by isothermal zonal connection, and then the whole structure part is heat treated, dimension measured, straightened, machined, and the stress of the whole process is detected and controlled. The present application realizes the control of the deformation of the rack body large structure part prepared by additive manufacturing through the process of isothermal zonal connection, and the real-time detection and control of stress, solves the problem of rapid additive manufacturing of the existing rack body large structure part, improves the production efficiency and reduces the production cost, ensures the mechanical properties of the material, and effectively avoids the deformation of the workpiece caused by the stress accumulation of integrated additive manufacturing. BRIEF DESCRIPTION OF DRAWINGS

[0059] Figure 1 The flow chart of the rack body large structure part additive manufacturing method of the present application;

[0060] Figure 2 The structure diagram of the rack body structure part of the present application;

[0061] Figure 3 The sub-component model of the rack body structure part of the present application;

[0062] ​1-Left beam, 2-Right beam, 3-Front frame, 4-Rear frame, 5-Crossbeam, a-Stress testing area;

[0063] Figure 4 This is a schematic diagram of the heat treatment fixture for the frame structure component of this invention:

[0064] 11-Inner square tube, 12-Long plate, 13-Square tube, 14-Outer square tube;

[0065] Figure 5 This is a schematic diagram of the straightening fixture for the frame structure of this invention:

[0066] 101-Frame structure component, 102-Ceramic heating element, 103-Supporting steel plate, 104-Jack, 105-Aluminum block, 106-Bolt. Detailed Implementation

[0067] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0068] Example 1

[0069] like Figures 1 to 5 As shown in the embodiments of the present invention, the method for controlling the deformation of large-scale additive manufacturing frames solves the problem of rapid additive manufacturing of existing large-scale frame structures, and includes the following steps:

[0070] First, there is the 3D model of the frame structure components, such as Figure 2 As shown, the frame structure is complex and difficult to manufacture using traditional methods. Its overall dimensions are approximately 2.5m long, 1.5m wide, and 0.5m high. This large size leads to significant stress in the integrated additive manufacturing process, causing workpiece deformation. Furthermore, the integrated additive manufacturing process has a long production cycle. Therefore, an isothermal zone connection process is used, along with real-time stress detection and control, to manage workpiece deformation. Figure 1 The flowchart below shows the additive manufacturing method for the large structural component of the frame according to the present invention. The specific method is as follows:

[0071] S1: Frame structure processing: Based on the structural information of the components that make up the frame structure, the frame model is optimized to obtain several sub-component models;

[0072] The specific steps are as follows:

[0073] S11: The rack body model is divided into five parts, namely, the front rack 3, the rear rack 4, the cross beam 5, the left side beam 1 and the right side beam 2, based on the structure information of the rack body structure member;

[0074] S12: The structure of the segmented sub-component model is optimized according to the requirements of the additive manufacturing process, for example, the straight corners are changed to 45-degree rounded corners, which can avoid stress concentration and optimize the additive path; a 4mm allowance is added inside and a 7mm allowance is added outside based on the segmented model; the hole positions that need to be machined later are filled, and an optimized sub-component model is generated, as shown in Figure 3

[0075] S2: Additive manufacturing: The optimized sub-component model is sliced using software, and different process parameters are adjusted according to the number of slices for additive manufacturing, obtaining a plurality of sub-component blanks, wherein the additive material is selected as a diameter of 1.2mm aluminum alloy 2319 welding wire, the base plate is a thickness of 30mm 2319 plate, the protective gas is pure argon with a purity of 99.999%, the gas flow is 25L / min, the additive voltage is 20V, and the welding speed is 10mm / s.

[0076] The additive manufacturing method adjusts different process parameters for additive manufacturing according to the number of software slices, which is specifically divided into three parts:

[0077] S21: Primer: the first layer of additive current is 95A, the wire feeding speed is 10m / min, and the other parameters remain unchanged;

[0078] S22: Filling: the middle transition layer additive current is 85A, the wire feeding speed is 8m / min, and the other parameters remain unchanged;

[0079] S23: Finishing: the last layer of additive current is 75A, the wire feeding speed is 6m / min, and the other parameters remain unchanged.

[0080] S3: Stress relief treatment: the five sub-component blanks obtained by additive manufacturing are subjected to stress relief annealing, and the heat treatment parameters are as follows: the temperature is raised to 175℃ at a rate of 100℃ / h, then the temperature is kept for 6h, and the furnace is discharged and air cooled to room temperature;

[0081] S4: Machining treatment: the five sub-component blanks after stress relief treatment are subjected to preliminary machining according to the machining information, obtaining five sub-components, and the positions that need to be machined are mainly the positions of the side beams, the cross beam and the front and rear racks for welding, and the positions of the front and rear racks that are not easy to machine after welding.

[0082] S5: Isothermal partitioning connection of sub-components: the five sub-components after machining are connected into a rack body structure member according to the size requirements, and the isothermal partitioning connection comprises the following three parts:

[0083] ​S51: Assembling the five sub-components according to the size requirements, leaving a margin of 3mm to prevent shrinkage of the weld during welding;

[0084] S52: Installing and fixing the assembled sub-components along the direction perpendicular to the welding direction using flexible steel rods. Three flexible steel rods are required on both sides of the side beams to prevent the side beams from shrinking inward during welding and to prevent the accumulation of residual stress during welding from causing deformation of the workpiece.

[0085] S53: Using ceramic to heat the sub-components fixed with the tooling to 200°C, then welding according to the diagonal symmetry, starting with spot welding, then corner welding, and finally full welding to obtain the rack structure.

[0086] S6: Workpiece heat treatment: heat treating the rack structure after isothermal zoning connection, solid solution system: heating at a rate of 100°C / h to 535°C, holding for 8h, then water cooling; aging system: heating at a rate of 100°C / h to 175°C, then holding for 4h, and air cooling to room temperature after discharge. The heat treatment tooling needs to be installed before heat treatment, and the tooling diagram is as follows Figure 4 , which includes: internal square tube 11 to prevent the side beams from shrinking inward, long plate 12 to prevent the side beams from twisting upward and downward, square tube 13 to connect each region, and external square tube 14 to prevent the side beams from deforming outward. The square tube 13 is a hollow steel tube with a wall thickness of 10mm, and the area where the internal square tube 11 connects to the workpiece needs to be isolated with aluminum blocks.

[0087] S7: Dimension measurement: three-dimensional scanning of the rack structure after heat treatment according to the size requirements, including:

[0088] S71: Obtaining the scanning information of the rack structure after heat treatment;

[0089] S72: Determining the size information of the rack structure after heat treatment according to the scanning information of the rack structure after heat treatment;

[0090] S73: Determining that the size information of the rack structure after heat treatment matches the corresponding model information. According to the matched information, it is found that the left side beam has been bent and deformed upward, and needs to be straightened.

[0091] S8: Straightening: straightening the left side beam using straightening tooling, the straightening method is to use ceramic heating and design tooling to apply pressure using a jack for straightening, and the specific straightening tooling is as follows Figure 5Wherein 101 is the frame structure, 102 is the ceramic heating sheet, 103 is the supporting steel plate, 104 is the jack, 105 is the aluminum block, and 106 is the bolt. First, use the ceramic heating sheet 102 to heat the left beam 1 part to 250℃, then use the jack 104 to apply pressure downward, so that the workpiece moves downward by 2mm every half hour, until the size meets the requirements, then turn off the heating, after cooling, turn on the heating for one hour again, repeat 3 times, finally stop heating, remove the straightening tool after 8 hours, and measure the size again, at this time the size of the frame has met the requirements.

[0092] S9: finishing: the frame structure with qualified size is finished according to the three-dimensional model.

[0093] S10: stress detection and control: after the structure is subjected to additive manufacturing, stress relief treatment, machining treatment, and isothermal zoned connection of sub-components, stress detection is required, and stress control is performed according to the detection results. The stress detection method is electrochemical blind hole detection method, and the stress control method is stress relief heat treatment. The detection position is Figure 3 a region, and the specific detection method includes the following five parts:

[0094] S101: select the to-be-detected region and the punching point on the frame structure, and install the strain gauge and the strain meter, and use the puncher to punch the to-be-detected region;

[0095] S102: after the value on the strain meter tends to be stable, the strain value measured by the strain gauge is substituted into the formula:

[0096]

[0097] The main stress of the frame structure can be calculated, wherein σ max , σ min are two main stresses in the frame structure; σ max is the maximum principal stress, and σ min is the minimum principal stress; the included angle of the three strain gauges is 120°; A and B are the release coefficients of the strain gauges, and the values thereof are obtained according to experimental calibration, and respectively reflect the energy release proportion of the material after experiencing a strain and stress; the release strains measured by the three sensitive grids in the strain gauge are ε0, ε 120 , and ε 240 .

[0098] S103: then, the stress detection is performed on the additive manufacturing (i.e. the frame structure before stress relief treatment) and the frame structure after stress relief treatment, respectively, to obtain the maximum principal stresses σ1 and σ2, and then the stress change rate δ1 during stress relief treatment is obtained according to the formula, as follows:

[0099]

[0100] S104: Detect the n-1th step and the n th step which need to be stress detected, and obtain σ n-1 and σ n Then, the stress change rate δ n of the n th step can be obtained according to the formula as follows:

[0101]

[0102] S105: Compare the stress change rate δ n of the n th step with the stress change rate δ1 after the stress relief treatment. If δ n ≥ δ1, the stress relief heat treatment is needed, otherwise, the stress relief heat treatment is not needed.

[0103] Table 1: Stress detection data of workpieces at different stages

[0104]

[0105] The obtained data are statistically analyzed, and the data are shown in Table 1. It can be seen from the table that the stress relief treatment after the additive manufacturing can greatly reduce the residual stress of the workpiece caused by the additive manufacturing, and prevent the deformation of the workpiece caused by the accumulation of the additive stress. The stress change rate of the workpiece after the isothermal partitioning connection is greater than the stress change rate after the stress relief treatment. Therefore, the stress relief heat treatment is performed after the isothermal partitioning connection, and it can be seen that the stress change rate after the stress relief heat treatment is obviously reduced, and the accumulation of the stress in the workpiece is reduced. Compared with the traditional manufacturing method and the integrated additive manufacturing method, the isothermal partitioning connection process is adopted, and the stress is detected and controlled in the process. The residual stress in the material can be eliminated step by step by the stress relief treatment, the deformation of the workpiece caused by the accumulation of the residual stress is prevented, and the production efficiency is improved.

[0106] The additive area and the welding area of the additive piece obtained in the example are subjected to tensile test, and the tensile properties of the additive area and the welding area of the example are obtained. The tensile properties of the example are compared with the tensile properties of the castings and forgings obtained by the conventional method, as shown in Table 2, and the test temperature is 23°C. It is found that the tensile properties of the additive area and the welding area of the additive piece obtained in the example are better than those of the castings, the tensile strength is slightly lower than that of the forgings, but the elongation is higher than that of the forgings. It can be seen that the combined process of additive and welding is adopted, and the stress is detected and controlled, which improves the production efficiency, ensures the mechanical properties of the material, and solves the problem of rapid additive manufacturing of the existing frame body large structure.

[0107] Table 2: Tensile properties of 2319 after heat treatment under different preparation methods

[0108] Example 2

[0109] The difference between this embodiment and embodiment 1 is only that:

[0110] In step S2, the additive voltage is 15V, the welding speed is 6mm / s, and the wire diameter is 0.8mm.

[0111] S21: Primer: the first layer additive current is 90A, the wire feeding speed is 11m / min, and other parameters remain unchanged;

[0112] S22: Filling: the intermediate transition layer additive current is 80A, the wire feeding speed is 9m / min, and other parameters remain unchanged;

[0113] S23: Cover: the last layer additive current is 70A, the wire feeding speed is 7m / min, and other parameters remain unchanged.

[0114] In step S3, the stress relief treatment includes the following contents: the sub-component blank obtained by additive manufacturing is subjected to stress relief annealing, and the heat treatment parameters are as follows: the temperature is raised to 150℃ at a rate of 50℃ / h, and then the temperature is kept for 2h, and the furnace is discharged and air cooled to room temperature;

[0115] In step S5, the isothermal partition connection refers to heating the region of the sub-component to be connected to 150℃ by a ceramic heating sheet, and the specific connection method is welding;

[0116] The frame structure after isothermal partition connection is subjected to heat treatment, and the solution system is as follows: the temperature is raised to 800℃ at a rate of 200℃ / h, and then the temperature is kept for 6h and water cooled; the aging system is as follows: the temperature is raised to 150℃ at a rate of 50℃ / h, and then the temperature is kept for 2h, and the furnace is discharged and air cooled to room temperature.

[0117] In step S8, first, use the ceramic heating sheet 102 to heat the left beam 1 part to 350℃, then use the jack 104 to apply pressure downward, so that the workpiece moves downward by 2mm every half hour, until the size meets the requirements, then turn off the heating, and after cooling, turn on the heating for one hour, repeat 5 times, and finally stop heating, remove the straightening tool after 8 hours, and measure the size again, at this time the frame size has met the requirements.

[0118] Embodiment 3

[0119] The difference between this embodiment and embodiment 1 is only that:

[0120] In step S2, the additive voltage is 25V, the welding speed is 15mm / s, and the wire diameter is 1.0mm.

[0121] S21: Primer: the first layer additive current is 100A, the wire feeding speed is 12m / min, and other parameters remain unchanged;

[0122] S22: Filling: the intermediate transition layer additive current is 90A, the wire feeding speed is 10m / min, and other parameters remain unchanged;

[0123] S23; cover face: last layer of additive current 80 A, wire feed speed 8 m / min, other parameters unchanged.

[0124] In step S3, the stress relief treatment includes the following: the additive manufacturing obtained sub-component blank is subjected to stress relief annealing, the heat treatment parameters are: at a heating rate of 80 ℃ / h, rising to 300 ℃, then holding for 4 h, and air cooling to room temperature after discharging from the furnace;

[0125] In step S5, the isothermal zoned connection refers to heating the region of the sub-component to be connected to 300 ℃ by a ceramic heating sheet, and the specific connection method is welding;

[0126] The rack body structure after isothermal zoned connection is subjected to heat treatment, the solution system is: at a heating rate of 150 ℃ / h, rising to 400 ℃, holding for 10 h, and then water cooling; the aging system is: at a heating rate of 75 ℃ / h, rising to 300 ℃, then holding for 6 h, and air cooling to room temperature after discharging from the furnace.

[0127] It should be understood that in order to simplify the present disclosure and aid in understanding one or more of the various inventive aspects, various features of the present application have sometimes been grouped into single embodiments, Figures, or descriptions of embodiments in the foregoing description of exemplary embodiments of the present application. The method of this disclosure should not, however, be construed to reflect an intention that the claimed application requires more features than those explicitly recited in each claim. Rather, it is the intention that the application aspects reside in less than all features of any disclosed embodiment. Accordingly, the claims are to be construed in accordance with the full scope of the recitations, with references to the Figures, the description of the embodiments, and the illustrative examples as the scope of the application.

[0128] While the present application has been described in terms of limited embodiments, those skilled in the art will appreciate that other embodiments can be devised in accordance with the teachings of the preceding description. Additionally, it should be noted that the language used in the specification has been principally selected for readability and instructional purposes and can not have been selected to expressly convey the scope of the inventive subject matter. Accordingly, the claims are not intended to be limited to the embodiments disclosed therein, but are to be accorded the full scope consistent with the language of the claims, wherein reference to an embodiment modifies but does not limit the scope of the claims. The disclosure of the application is illustrative only and not restrictive of the scope of the application, which is defined by the claims.

[0129] The above only is the preferred embodiment of the present application, it should be pointed out that for those skilled in the art, without departing from the principles of the present application, can also make a number of improvements and refinements, these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. A method for controlling the deformation of large structural components manufactured by additive manufacturing, characterized in that, Includes the following steps: S1: Frame structure processing: Based on the structural information of the components that make up the frame structure, the frame model is optimized to obtain several sub-component models; S2: Additive manufacturing: The optimized sub-part model is sliced ​​using lugoPNT software, and additive manufacturing is performed using different process parameters according to the number of slice layers to obtain several sub-part blanks; S3: Stress relief treatment: Stress relief treatment is performed on several sub-component blanks obtained from additive manufacturing; S4: Machining: The stress-relief blanks of several sub-components are initially machined according to the dimensional information to obtain several sub-components; S5: Isothermal partitioning connection of sub-components: After machining, several sub-components are connected isothermally in sections according to dimensional requirements at 150℃-300℃ to form a frame structure. S6: Heat treatment of workpiece: Heat treatment is performed on the frame structure after isothermal partition connection. Heat treatment fixtures are installed before heat treatment. S7: Dimension Measurement: Measure the dimensions of the heat-treated frame structure components according to the dimensional requirements; S8: Correction: Correct the frame structure components that do not meet the dimensional requirements using correction fixtures until the dimensions meet the requirements; S9: Finishing: Milling the frame structure parts that have passed the dimensional measurement. S10: Stress detection and control: After the frame structure components undergo additive manufacturing, stress relief treatment, machining, and isothermal zoning connection of sub-components, stress detection is required, and stress control is carried out based on the detection results.

2. The method according to claim 1, characterized in that, In S1, the structural information includes the front frame, rear frame, crossbeams, left beam, and right beam of the frame structure.

3. The method according to claim 1, characterized in that, In S1, the optimization processing of the frame model includes: S11: Based on the structural information of the components that make up the frame structure, the frame model is divided into several sub-component models; S12: Optimize the structure of the segmented sub-component models according to the additive manufacturing process requirements, including adding margin and handling corners.

4. The method according to claim 1, characterized in that, In S2, the additive manufacturing is electric arc additive manufacturing; The additive manufacturing method adjusts different process parameters according to the number of layers in the software slice, and is specifically divided into three parts: S21: Base pass: First layer additive current 90-100A, wire feed speed 10-12m / min, additive voltage 15V-25V, welding speed 6mm / s-15mm / s; S22: Filler: Intermediate transition layer additive current 80-90A, wire feed speed 8-10m / min, additive voltage 15V-25V, welding speed 6mm / s-15mm / s; S23； Cover layer: Additive current 70-80A, wire feed speed 6-8m / min, additive voltage 15V-25V, welding speed 6mm / s-15mm / s.

5. The method according to claim 1, characterized in that, In S3, the stress relief treatment includes the following: stress relief annealing is performed on the sub-part blanks obtained by additive manufacturing. The heat treatment parameters are: heating to 150-300℃ at a heating rate of 50-100℃ / h, then holding at that temperature for 2-6 hours, and then air cooling to room temperature after removal from the furnace.

6. The method according to claim 1, characterized in that, In S6, the frame structure components connected by isothermal zones are subjected to heat treatment. Solution treatment: heating at a rate of 100-200℃ / h to 400-800℃, holding for 6-10h, and then water cooling. Aging treatment: heating at a rate of 50-100℃ / h to 150-300℃, then holding for 2-6h, and then air cooling to room temperature after removal from the furnace.

7. The method according to claim 1, characterized in that, In S7, the method for dimensional measurement is three-dimensional scanning, specifically including: S71: Obtain scan information of the frame structure that has completed heat treatment, including external contour and three-dimensional dimensions; S72: Determine the dimensional information of the frame structure that has completed heat treatment based on the scanning information of the frame structure that has completed heat treatment, including length, width, height, angle, and surface roughness; S73: Determine the matching of the dimensional information of the frame structure components that have completed heat treatment with the corresponding model information.

8. The method according to claim 1, characterized in that, In S10, the stress detection method is the electrochemical blind hole detection method, and the stress control method is stress relief heat treatment.

9. The method according to claim 1, characterized in that, In S10, the stress regulation based on the detection results is divided into the following five parts: S101: Select the area to be measured and the drilling point on the frame structure, install strain gauges and strain meters, and use a drilling machine to drill holes in the area to be measured. S102: After the values ​​on the strain gauge have stabilized, substitute the strain values ​​measured by the strain gauge into the formula: The magnitude of the principal stresses of the frame structure members can then be calculated, where σ max σ min These are the two principal stresses within the frame structure; σ max For the maximum principal stress, σ min The minimum principal stress is given; the included angle of the three strain gauges is 120°; A and B are the release coefficients of the strain gauges, whose values ​​are obtained from experimental calibration, reflecting the proportion of energy released by the material after experiencing one strain and stress, respectively; the release strains measured by the three sensitive grids in the strain gauge are ε0, ε... 120 ε 240 ; S103: Then, stress tests were performed on the frame structure components after additive manufacturing and stress relief treatment, respectively, to obtain the maximum principal stresses σ1 and σ2. Then, the stress change rate δ1 during stress relief treatment was calculated according to the following formula: S104: Perform stress testing on steps n-1 and n that require subsequent stress detection, and obtain σ respectively. n-1 and σ n Then, the stress change rate δ in the nth step can be obtained according to the formula. n The formula is as follows: S105: The stress change rate δ in step n n Compared with the stress change rate δ1 after stress relief treatment, if δ n If the value is ≥δ1, then stress-relieving heat treatment is required; otherwise, it is not required.

10. The method according to claim 1, characterized in that, The frame structure components are large-sized and complex structural components; the large size of the frame structure components refers to the overall dimensions, with a length ≥ 2.5m, a width ≥ 1.5m, and a height ≥ 0.5m; the complex structure refers to the fact that the frame structure components include the front frame, the rear frame, the crossbeams, the left beam, and the right beam.

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