A straightening reinforcement device and a reinforcement method

Abstract

The application discloses a shape correcting and strengthening device and a strengthening method, relates to the field of post-processing technologies of electric arc additive manufacturing, and comprises a mold, which forms a mold cavity in the interior after being closed; a mandrel is arranged in the mold cavity, and the mandrel has an outer peripheral surface matched with the shape of an inner hole of a to-be-processed overhanging part; a flexible force transmission medium is arranged in the mold cavity, the outer peripheral surface of the flexible force transmission medium is matched with the shape of the inner wall of the mold cavity, the flexible force transmission medium has a hollow structure matched with the shape of the to-be-processed overhanging part, and a forming cavity for accommodating the to-be-processed overhanging part is formed between the flexible force transmission medium and the mandrel; a force applying punch is inserted into the mold cavity from one end of the mold cavity and is pressed against the end surface of the flexible force transmission medium; a limiting punch is pressed against the mandrel and the mold from the end of the mold cavity away from the force applying punch, axial pressure is converted into normal bulging force and tangential friction force through the flexible force transmission medium, and limited controllable plastic deformation correction and mechanical property strengthening of the overhanging part are realized.

Description

Technical Field

[0001] This invention relates to the field of post-processing technology in arc additive manufacturing, and in particular to a shaping and strengthening device and a strengthening method. Background Technology

[0002] Additive manufacturing (AM) technology is based on a three-dimensional digital model. It discretizes the part model and then heats and clads materials according to a pre-set forming trajectory, layer by layer, through melting and solidification, to ultimately form a three-dimensional solid part. Compared with traditional subtractive or equal-material manufacturing processes such as machining, casting, and forging, additive manufacturing is a bottom-up, mold-free, integrated advanced forming technology. This technology overcomes the limitations of traditional manufacturing processes, such as insufficient flexibility, low material utilization, and high costs. It significantly expands the range of feature dimensions for parts and greatly reduces the processing difficulty of parts with extreme dimensions and complex structures. It has broad application prospects in many fields such as aerospace, automotive, shipbuilding, and defense industries, and is one of the key development directions of advanced manufacturing technology in my country.

[0003] Metal additive manufacturing technology can be divided into three main categories based on the type of heat source: laser additive manufacturing, electron beam additive manufacturing, and arc additive manufacturing. Among them, wire and arc additive manufacturing (WAAM) uses an electric arc heat source to heat and melt metal wires, depositing them layer by layer through droplet transfer to form three-dimensional solid parts. Compared to other additive manufacturing technologies, WAAM has significant advantages such as high deposition efficiency, short deposition cycle, and low production cost. It also has no special restrictions on the forming environment, making it particularly suitable for efficient additive forming of large, complex structural parts in any spatial path.

[0004] Hollow overhang structures are a typical geometric feature of key components in the aerospace and defense industries, with extremely stringent requirements for forming accuracy and mechanical properties. In conventional additive manufacturing, overhang structures typically require the addition of support structures to ensure forming stability (such as in FDM technology). After the part is additively manufactured, the support structure must be removed from the part surface. This operation not only increases post-processing steps but also easily damages the surface integrity of the part, affecting its final performance. Furthermore, for large and complex parts, the optimized design and efficient printing of the support structure itself present significant technical challenges; especially in metal additive manufacturing, the high density of metal materials places higher demands on the fixation, positioning, heat transfer, and deformation resistance of the support structure, further increasing the complexity of the support structure design.

[0005] To avoid the many problems caused by the support structure, the unsupported additive manufacturing technology has been proposed in recent years. By optimizing the combination of process parameters and processing strategies, the flowability of molten metal is reduced and the self-supporting ability of the overhanging area is enhanced, thereby realizing high-precision additive manufacturing of hollow feature parts. However, the unsupported process of arc additive manufacturing is still in the preliminary research stage, and the following prominent problems still exist: (1) The combined effect of molten metal flow, thermal stress and residual stress causes the parts to warp and deform, and the forming accuracy is difficult to meet the design requirements; (2) The mechanical properties of deposited metal are much different from those of forgings; (3) Metallurgical defects such as pores and cracks cause the fatigue strength of the parts to be greatly reduced, resulting in insufficient service reliability.

[0006] Currently, for arc additive manufacturing of straight-walled parts, mechanical deformation post-processing is commonly used to control deformation and eliminate residual stress. Common mechanical post-processing methods include rolling, ultrasonic impact, vibration treatment, and hammering. By applying a unidirectional load along the additive direction, metallurgical defects can be improved, grains refined, residual stress eliminated, and mechanical properties enhanced to some extent. However, for overhanging structures, directly applying pressure or impact along the deposition direction can easily damage the overhanging structure and may induce secondary warping deformation, severely affecting forming accuracy.

[0007] Furthermore, existing technologies in this field employ fluid media (such as high-pressure oil) for shaping and strengthening additively manufactured hollow components. For example, a high-pressure fluid medium is used as the pressure transmission medium, and the fluid pressure is transmitted to the workpiece surface through a pressurized oil circuit to achieve shaping. However, this fluid shaping scheme has the following inherent shortcomings in practical applications: First, the high-pressure liquid medium may seep into the pores and microcracks on the workpiece surface during the pressurization process. If it is not completely drained after shaping, the residual liquid will vaporize in the high-temperature and high-pressure service environment of aerospace parts, thereby seriously affecting the microstructure and service reliability of the parts; Second, fluid medium shaping requires complex sealing components to prevent high-pressure liquid leakage, resulting in complex equipment structures and high costs; Third, the pressure control accuracy of high-pressure liquid is affected by various factors such as temperature and medium viscosity, and the process stability needs to be improved. Summary of the Invention

[0008] The purpose of this invention is to provide a shaping and strengthening device and a strengthening method to solve the problems existing in the prior art. By using a flexible force transmission medium, axial pressure is converted into normal expansion force and tangential friction force, thereby realizing the limited and controllable plastic deformation shaping and mechanical property strengthening of the suspended component.

[0009] To achieve the above objectives, the present invention provides the following solution: The present invention provides a shape-correcting and strengthening device, comprising: A mold, which forms a mold cavity inside after the mold is closed; A mandrel is disposed in the mold cavity, the mandrel having an outer peripheral surface adapted to the shape of the inner hole of the overhanging part to be processed; A flexible force transmission medium is disposed in the mold cavity. The outer peripheral surface of the flexible force transmission medium is adapted to the shape of the inner wall of the mold cavity, and the flexible force transmission medium has a hollow structure adapted to the shape of the suspended part to be processed. A forming cavity for accommodating the suspended part to be processed is formed between the flexible force transmission medium and the mandrel. A force-applying punch, inserted into the mold cavity from one end and pressing against the end face of the flexible force-transmitting medium, is used to connect to a force-applying device to receive and transmit axial pressure; and, A limiting punch, which abuts against the mandrel and the mold at one end away from the force-applying punch in the mold cavity, and the limiting punch is used to connect with the force-receiving device to limit the axial displacement of the mandrel.

[0010] Optionally, the mold includes an upper mold and a lower mold, the upper mold and the lower mold cooperating with each other to form the mold cavity after the mold is closed.

[0011] Optionally, the upper mold has a plurality of positioning pins on the side facing the lower mold, and the lower mold has a plurality of pin holes that cooperate with the positioning pins.

[0012] Optionally, the mandrel is a variable diameter mandrel, which has a first column segment, a variable diameter segment, and a second column segment. The diameter of the first column segment is smaller than the diameter of the second column segment. The variable diameter segment is located between the first column segment and the second column segment, and the outer diameter of the variable diameter segment smoothly transitions from the first column segment to the second column segment.

[0013] Optionally, a limiting sleeve is fitted onto the first column segment, the limiting sleeve being used to axially limit the end face of the suspended part to be processed.

[0014] Optionally, the wall thickness of the limiting sleeve is consistent with the wall thickness of the hanging part to be processed.

[0015] Optionally, the flexible force transmission medium is a hollow polyurethane medium, and gaps are left between the hollow polyurethane medium and the outer wall of the mandrel and the inner wall of the mold cavity.

[0016] Optionally, the force-applying punch has an annular structure and is coaxially connected to the end face of the flexible force-transmitting medium, and has an opening at its center for the mandrel to extend out.

[0017] A strengthening method using the aforementioned alignment and strengthening device is also provided, comprising the following steps: S1. Prepare a hollow hanging part, cool it and then perform surface treatment to obtain the hanging part to be processed; S2. Insert the suspended part to be processed into the mandrel, and after installing the flexible force transmission medium, put the whole into the mold cavity; S3. Close the mold and position it, limit the axial feed of the punch, and press against the mandrel and the mold; S4. The force-applying punch feeds and applies axial pressure to the flexible force-transmitting medium, causing the flexible force-transmitting medium to deform and radially compress the suspended part to be processed. S5. The suspended part to be processed undergoes plastic deformation under the combined action of pressure perpendicular to its outer wall and friction along its outer wall until it fits the outer wall of the mandrel, thus completing the shaping and strengthening. S6. Open the mold and remove the shaped and reinforced hanging parts.

[0018] Optionally, in step S4, the feed amount of the force-applying punch is calculated based on the deformation of the flexible force-transmitting medium.

[0019] The present invention achieves the following technical effects compared to the prior art: In this invention, a shaping and strengthening device constrains the outer boundary of the workpiece through a mold cavity, a mandrel provides an ideal dimensional reference for the inner hole of the workpiece, and a flexible force transmission medium converts the axial pressure of the force-applying punch into a multi-directional load acting on the inner and outer surfaces of the workpiece. Under the combined action of normal pressure perpendicular to its outer wall and tangential frictional force along its outer wall, the workpiece undergoes plastic deformation until it completely conforms to the outer wall of the mandrel, achieving quantitative shaping. This process applies a multi-directional and stable load, without damaging the overhanging structure. Simultaneously, the pores inside the workpiece are compacted under pressure, and residual tensile stress is converted into residual compressive stress, thus strengthening the mechanical properties. This addresses the problems of warping deformation and poor forming accuracy caused by thermal stress and residual stress in existing unsupported arc additive manufacturing of hollow overhanging parts, as well as insufficient mechanical properties due to pore cracks in deposited metals. By using a flexible force transmission medium to convert axial pressure into normal expansion force and tangential frictional force, it achieves limited and controllable plastic deformation shaping and mechanical property strengthening of the overhanging part. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of a shape-correcting and strengthening device according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the pre-molding state during the shaping and strengthening process according to an embodiment of the present invention; Figure 3This is a schematic diagram of the assembly position of the hanging component to be processed in one embodiment of the present invention; Figure 4 This is a schematic diagram of the assembled hanging component in one embodiment of the present invention; Figure 5 This is a schematic diagram of the mold closing state during the shaping and strengthening process in one embodiment of the present invention; Figure 6 This is a front sectional view of the mold-closing state during the shaping and strengthening process in one embodiment of the present invention; Figure 7 This is an embodiment of the electric arc additive manufacturing of a suspended part to be processed, as disclosed in this invention.

[0022] In the diagram: 1. Force-applying punch; 2. Mandrel; 3. Upper die; 4. Limiting punch; 5. Lower die; 6. Flexible force transmission medium; 7. Limiting sleeve; 8. Overhanging part to be processed. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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 are within the scope of protection of the present invention.

[0024] The purpose of this invention is to provide a shaping and strengthening device and a strengthening method to solve the problems existing in the prior art. By using a flexible force transmission medium, axial pressure is converted into normal expansion force and tangential friction force, thereby realizing the limited and controllable plastic deformation shaping and mechanical property strengthening of the suspended component.

[0025] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0026] like Figures 1 to 7As shown, the present invention provides a shaping and strengthening device, including a mold, a mandrel 2, a flexible force transmission medium 6, a force-applying punch 1, and a limiting punch 4; after the mold is closed, a mold cavity is formed inside, the mandrel 2 is disposed in the mold cavity, the mandrel 2 has an outer peripheral surface adapted to the shape of the inner hole of the suspended part 8 to be processed, the flexible force transmission medium 6 is disposed in the mold cavity, the outer peripheral surface of the flexible force transmission medium 6 is adapted to the shape of the inner wall of the mold cavity, and the flexible force transmission medium 6 has a shape adapted to the outer shape of the suspended part 8 to be processed. The adaptable hollow structure forms a forming cavity between the flexible force transmission medium 6 and the mandrel 2 to accommodate the suspended part 8 to be processed. The force-applying punch 1 is inserted into the mold cavity from one end and presses against the end face of the flexible force transmission medium 6. The force-applying punch 1 is used to connect with the force-applying device to receive and transmit axial pressure. The limiting punch 4 abuts against the mandrel 2 and the mold from the end of the mold cavity away from the force-applying punch 1. The limiting punch 4 is used to connect with the force-receiving device to limit the axial displacement of the mandrel 2.

[0027] Understandably, in the unsupported forming process of hollow suspended parts during arc additive manufacturing, the combined effects of molten metal flow, thermal stress, and residual stress cause warping deformation of the workpiece. Existing mechanical post-processing methods apply loads in a single direction, which can easily damage the suspended characteristics when applied directly to the suspended structure.

[0028] In this invention, a shaping and strengthening device constrains the outer boundary of the workpiece through a mold cavity, a mandrel 2 provides an ideal dimensional reference for the inner hole of the workpiece, and a flexible force transmission medium 6 converts the axial pressure of the force-applying punch 1 into a multi-directional load acting on the inner and outer surfaces of the workpiece. Under the combined action of normal pressure perpendicular to its outer wall and tangential frictional force along its outer wall, the workpiece undergoes plastic deformation until it completely conforms to the outer wall of the mandrel 2, achieving quantitative shaping. This process applies a multi-directional and stable load, without damaging the overhanging structure. Simultaneously, the pores inside the workpiece are compacted under pressure, and residual tensile stress is converted into residual compressive stress, thus strengthening the mechanical properties. This addresses the problems of warping deformation and poor forming accuracy caused by thermal stress and residual stress in existing unsupported arc additive manufacturing of hollow overhanging parts, as well as insufficient mechanical properties due to pore cracks in deposited metals. By using the flexible force transmission medium 6 to convert axial pressure into normal expansion force and tangential frictional force, it achieves limited and controllable plastic deformation shaping and mechanical property strengthening of the overhanging part.

[0029] In one embodiment, the mold includes an upper mold 3 and a lower mold 5, which cooperate with each other to form a mold cavity after being closed. The split mold structure facilitates the placement and removal of the workpiece. The mold cavity formed after the mold is closed provides a rigid boundary constraint on the outer peripheral surface of the flexible force transmission medium 6, so that the flexible force transmission medium 6 can only deform inward and in the axial direction when squeezed, and efficiently converts the axial pressure into a normal expansion force acting on the workpiece.

[0030] Based on this embodiment, in some examples, the upper mold 3 and the lower mold 5 have symmetrical structures, each including a concave cavity located in the middle. The concave cavity extends through the front and rear of the upper mold 3 and the lower mold 5. After mold closing, the two concave cavities combine to form a mold cavity that conforms to the shape of the overhanging part 8 to be processed. The symmetrical structure facilitates the processing and manufacturing of the upper mold 3 and the lower mold 5, and the alignment accuracy of the mold cavity is high after mold closing. In other examples, the mold is not limited to including the upper mold 3 and the lower mold 5. Depending on actual needs, it can also be four or eight mold-parting structures, etc. After each mold-parting structure is closed, it forms a mold cavity that conforms to the shape of the overhanging part 8 to be processed.

[0031] Furthermore, the rear edges of the upper mold 3 and the lower mold 5 have flanges that bulge towards the center of the concave cavity, thereby limiting the workpiece 8 to be machined from the rear of the concave cavity. This flange structure gives the mold cavity an open opening facing the front of the mold and an inward opening facing the rear of the mold. The workpiece is inserted from the open opening, and the inward opening prevents the workpiece from moving backward during the application of force, while providing an axial positioning reference for the rear end of the mandrel 2.

[0032] In some other embodiments, the upper mold 3 has multiple locating pins on the side facing the lower mold 5, and the lower mold 5 has multiple pin holes that mate with the locating pins. The engagement of the locating pins and pin holes ensures accurate alignment of the upper mold 3 and the lower mold 5 during mold closing, preventing mold cavity shape deviation and eccentric deformation of the flexible force transmission medium 6 due to mold misalignment. After mold closing, the locating pins move axially along the pin holes, restricting the lateral relative movement between the two molds and ensuring the stability of the mold cavity during force application.

[0033] In one embodiment, the mandrel 2 is a variable-diameter mandrel, which has a first column section, a variable-diameter section, and a second column section. The diameter of the first column section is smaller than the diameter of the second column section. The variable-diameter section is located between the first and second column sections, and its outer diameter smoothly transitions from the first to the second column section. The inner hole of the hollow suspension component is usually a variable-diameter structure. The outer diameter of the variable-diameter section of the variable-diameter mandrel matches the ideal size of the workpiece's inner hole, providing a final shape reference for the workpiece's shaping. The smoothly transitioning variable-diameter section ensures that the workpiece deforms uniformly along the axial direction during the shaping process, avoiding local stress concentration caused by abrupt changes in cross-section.

[0034] Among them, the variable diameter section of the mandrel 2 is a conical structure with a conical outer circumferential surface. The conical outer circumferential surface matches the shape of the inner hole of the workpiece. After the workpiece is shaped, the inner wall completely fits the conical outer circumferential surface, thus achieving precise correction of the inner diameter.

[0035] Preferably, the second column section is fitted with the inner opening of the mold cavity without clearance. The clearance-free fit ensures that the mandrel 2 remains concentric with the mold cavity during the application of force. The radial distance between the variable diameter section and the mold cavity remains consistent along the axial direction, ensuring the uniformity of the deformation of the flexible force transmission medium 6. The end face of the second column section abuts against the limiting punch 4 during use, forming axial positioning.

[0036] In one embodiment, a limiting sleeve 7 is fitted onto the first column section. The limiting sleeve 7 is used to axially limit the workpiece from the end face of the suspended part 8 to be processed. When the workpiece is subjected to normal pressure and friction, it may move axially in addition to radial deformation. The limiting sleeve 7 is provided on the first column section and abuts against the workpiece from the small end face of the workpiece to prevent it from sliding axially during the straightening process. The limiting sleeve 7 restricts the workpiece to a predetermined position in the diameter-changing section, ensuring the accurate axial position of the workpiece after straightening.

[0037] Among them, the limiting sleeve 7 and the mandrel 2 are in clearance fit. When the limiting sleeve 7 and the mandrel 2 are in fit, they are coaxial. The clearance fit facilitates the insertion and removal of the limiting sleeve 7. The coaxial setting ensures that the axial limiting surface of the limiting sleeve 7 on the workpiece is perpendicular to the axis of the mandrel 2, and the workpiece is subjected to uniform force.

[0038] In one embodiment, the wall thickness of the limiting sleeve 7 is consistent with the wall thickness of the hanging part 8 to be processed, and the wall thickness of the limiting sleeve 7 is consistent with the wall thickness of the workpiece, so that the flexible force transmission medium 6 has a consistent wall thickness deformation space at the corresponding positions of the limiting sleeve 7 and the workpiece, avoiding discontinuous deformation of the flexible force transmission medium 6 due to differences in wall thickness, and ensuring that the pressure is uniformly transmitted in the transition area between the workpiece and the limiting sleeve 7.

[0039] In one embodiment, the flexible force transmission medium 6 is a hollow polyurethane medium, with gaps maintained between the hollow polyurethane medium and the outer wall of the mandrel 2 and the inner wall of the mold cavity. The hollow polyurethane medium is a solid elastomer; under pressure, it converts axial pressure into a normal expansion force perpendicular to the outer wall of the workpiece and a tangential frictional force along the outer wall through its own elastic deformation. This eliminates the need for a sealing structure, fundamentally avoiding the risk of high-pressure liquid seeping into the workpiece's pores. The gaps maintained before deformation facilitate the insertion of the workpiece and the removal of the medium. After deformation, the polyurethane medium completely adheres to the mold and workpiece surfaces, forming a uniform pressure transmission surface.

[0040] In some specific examples, the gap between the hollow polyurethane medium and the outer wall of the mandrel 2 and the inner wall of the mold cavity is 0.3 to 0.5 mm. This gap range ensures ease of assembly while limiting the pre-deformation of the polyurethane medium, so that the stroke of the force-applying punch 1 mainly acts on the plastic deformation of the workpiece, thereby improving the shaping efficiency.

[0041] In one embodiment, the force-applying punch 1 has an annular structure and is coaxially connected to the end face of the flexible force-transmitting medium 6, with an opening at its center for the mandrel 2 to extend out. The annular structure of the force-applying punch 1 allows it to freely enter and exit axially from the open end of the mold cavity. The annular end face evenly presses against the force-bearing end face of the flexible force-transmitting medium 6, so that the axial pressure is evenly transmitted circumferentially, avoiding uneven deformation of the medium and eccentric force on the workpiece caused by eccentric loading. The central opening allows the mandrel 2 to extend out, so that the force-applying punch 1 does not interfere with the mandrel 2 during the force application process. The mandrel 2 can be independently axially positioned from the other end by the limiting punch 4.

[0042] Among them, the force-applying punch 1, mandrel 2, upper die 3 and lower die 5 are all provided with rounded corners. The rounded corner structure prevents the surface of the die and mandrel 2 from being damaged after the punch is fed, while reducing stress concentration and extending the service life of the die and punch.

[0043] Furthermore, a strengthening method using the aforementioned shape-correcting and strengthening device is also provided, comprising the following steps: S1. Prepare a hollow hanging part, cool it and then perform surface treatment to obtain the hanging part to be processed 8. S2. Insert the hanging part 8 to be processed into the mandrel 2, and after fitting the flexible force transmission medium 6, put the whole into the mold cavity. S3. Close the mold and position it. Limit the axial feed of the punch 4 and press against the mandrel 2 and the mold. S4. The force-applying punch 1 feeds in and applies axial pressure to the flexible force transmission medium 6, causing the flexible force transmission medium 6 to deform and radially compress the suspended part 8 to be processed. S5. Under the combined action of pressure perpendicular to its outer wall and friction along its outer wall, the hanging part 8 undergoes plastic deformation until it fits against the outer wall of the mandrel 2, thus completing the shaping and strengthening. S6. Open the mold and remove the corrected and reinforced hanging parts; This method utilizes the combined effect of the normal bulging force and tangential friction force generated by the flexible force transmission medium 6 and the mold constraint to induce limited and controllable plastic deformation in the suspended component, achieving quantitative and controllable warpage correction. Simultaneously, under the action of a triaxial stress field, the grains are refined, porosity is reduced, and residual tensile stress is converted into residual compressive stress, significantly enhancing tensile and fatigue properties.

[0044] Regarding the feed amount of the force-applying punch 1 in step S4, in one implementation, the feed amount of the force-applying punch 1 is calculated based on the deformation amount of the flexible force transmission medium 6. The deformation amount of the flexible force transmission medium 6 is affected by the gap compensation amount and the porosity of the workpiece. The feed amount calculated can accurately control the shaping amount and avoid excessive deformation of the workpiece due to excessive force application.

[0045] After step S5 is completed, the force-applying punch 1 continues to feed 0.3 to 0.5 mm to prevent the suspended part 8 to be processed from springing back after the pressure is released. The continued feeding compensates for the dimensional shrinkage caused by the elastic springback, ensuring that the dimensions of the calibrated workpiece are stable within the accuracy range of the outer wall dimensions of the mandrel 2.

[0046] To facilitate understanding, a specific example is used below to illustrate this shape-strengthening method. Taking the arc additive manufacturing of a hollow suspension component from 6063 aluminum alloy as an example, its shape is as follows: Figure 7 As shown, the dimensions are: large end inner diameter 60mm, small end inner diameter 40mm, height 100mm, wall thickness 5mm, substrate size 100×100mm, thickness 10mm. The process includes the following steps: S1. Layers are stacked on the substrate, with the path being a circle with an increasing radius for each layer. The layer height is 2.5 mm, and there are a total of 40 layers. After cooling, the irregular surfaces of the substrate and the hanging parts are removed, and the surface is smoothed to obtain the hanging parts to be processed 8.

[0047] S2. Insert the hanging part 8, the limiting sleeve 7, and the hollow polyurethane medium into the mandrel 2 in sequence, and then place the whole assembly into the concave cavity of the lower mold 5 of the shaping device. After the hanging part 8 is deformed, its inner diameter is slightly larger than the outer diameter of the mandrel 2, leaving a certain gap between them.

[0048] S3. The upper die 3 moves downward and closes with the lower die 5 to form a mold cavity. The limiting punch 4 is fed axially until it comes into contact with the end face of the mold and the mandrel 2, and maintains a certain pressure.

[0049] S4. The force-applying punch 1 feeds in. After calculating the deformation of the hollow polyurethane medium, the feed amount of the force-applying punch 1 is 5.5mm. Pressure is applied to the hollow polyurethane medium, causing it to deform and completely adhere to the mold and the surface of the suspended part 8 to be processed.

[0050] S5. The hollow polyurethane medium is continuously pressurized. The axial pressure of the force-applying punch 1 is transmitted by the hollow polyurethane medium. The suspended part 8 to be processed is subjected to pressure perpendicular to its outer wall and friction along its outer wall, resulting in plastic deformation until it completely fits the outer wall of the mandrel 2, thus completing the shaping and strengthening.

[0051] S6. The force-applying punch 1 and the limiting punch 4 retract simultaneously. Because the pendant 8 to be processed has undergone plastic deformation and is tightly fitted with the mandrel 2, a certain amount of force needs to be applied to the small end of the mandrel 2, and the mandrel 2 is pushed out along the right end of the mold. The upper mold 3 and the lower mold 5 separate, the hollow polyurethane medium returns to its original shape, and the hollow polyurethane medium and the shaped and reinforced pendant 8 to be processed are taken out in sequence.

[0052] In this example, after the aluminum alloy pendant is shaped and strengthened, the deformation generated during the additive manufacturing process is corrected, the internal pores are compacted under pressure, and the fatigue strength is improved. This shaped and strengthened method does not require a sealing structure, the polyurethane medium does not penetrate into the workpiece pores, and it does not damage the workpiece. The hollow polyurethane medium can be reused, which is in line with the concept of green manufacturing.

[0053] Any adaptive changes made according to actual needs are within the scope of protection of this invention.

[0054] It should be noted that, for those skilled in the art, it is obvious that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0055] Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention. Furthermore, those skilled in the art will recognize that, based on the ideas of this invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. A shape-correcting and strengthening device, characterized in that, include: A mold, which forms a mold cavity inside after the mold is closed; A mandrel is disposed in the mold cavity, the mandrel having an outer peripheral surface adapted to the shape of the inner hole of the overhanging part to be processed; A flexible force transmission medium is disposed in the mold cavity. The outer peripheral surface of the flexible force transmission medium is adapted to the shape of the inner wall of the mold cavity, and the flexible force transmission medium has a hollow structure adapted to the shape of the suspended part to be processed. A forming cavity for accommodating the suspended part to be processed is formed between the flexible force transmission medium and the mandrel. A force-applying punch, inserted into the mold cavity from one end and pressing against the end face of the flexible force-transmitting medium, is used to connect to a force-applying device to receive and transmit axial pressure; and, A limiting punch, which abuts against the mandrel and the mold at one end away from the force-applying punch in the mold cavity, and the limiting punch is used to connect with the force-receiving device to limit the axial displacement of the mandrel.

2. The straightening and strengthening device according to claim 1, characterized in that, The mold includes an upper mold and a lower mold. The upper mold and the lower mold cooperate with each other and together form the mold cavity after the mold is closed.

3. The straightening and strengthening device according to claim 2, characterized in that, The upper mold has multiple positioning pins on the side facing the lower mold, and the lower mold has multiple pin holes that cooperate with the positioning pins.

4. The straightening and strengthening device according to claim 1, characterized in that, The mandrel is a variable diameter mandrel, which has a first column section, a variable diameter section and a second column section. The diameter of the first column section is smaller than the diameter of the second column section. The variable diameter section is located between the first column section and the second column section, and the outer diameter of the variable diameter section smoothly transitions from the first column section to the second column section.

5. The straightening and strengthening device according to claim 4, characterized in that, A limiting sleeve is fitted onto the first column segment, and the limiting sleeve is used to axially limit the end face of the suspended part to be processed.

6. The straightening and strengthening device according to claim 5, characterized in that, The wall thickness of the limiting sleeve is the same as the wall thickness of the hanging part to be processed.

7. The straightening and strengthening device according to claim 1, characterized in that, The flexible force transmission medium is a hollow polyurethane medium, and gaps are left between the hollow polyurethane medium and the outer wall of the mandrel and the inner wall of the mold cavity.

8. The straightening and strengthening device according to claim 1, characterized in that, The force-applying punch has a ring-shaped structure and is coaxially connected to the end face of the flexible force-transmitting medium, and has an opening at its center for the mandrel to extend out.

9. A strengthening method using the shape-correcting and strengthening device as described in any one of claims 1 to 8, characterized in that, Includes the following steps: S1. Prepare a hollow hanging part, cool it and then perform surface treatment to obtain the hanging part to be processed; S2. Insert the suspended part to be processed into the mandrel, and after installing the flexible force transmission medium, put the whole into the mold cavity; S3. Close the mold and position it, limit the axial feed of the punch, and press against the mandrel and the mold; S4. The force-applying punch feeds and applies axial pressure to the flexible force-transmitting medium, causing the flexible force-transmitting medium to deform and radially compress the suspended part to be processed. S5. The suspended part to be processed undergoes plastic deformation under the combined action of pressure perpendicular to its outer wall and friction along its outer wall until it fits the outer wall of the mandrel, thus completing the shaping and strengthening. S6. Open the mold and remove the shaped and reinforced hanging parts.

10. The strengthening method according to claim 9, characterized in that, In step S4, the feed amount of the force-applying punch is calculated based on the deformation of the flexible force-transmitting medium.

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