Multi-inner-rib complex thin-walled magnesium alloy component near-net forming die and method

Abstract

This invention discloses a near-net-shape forming mold and forming method for complex thin-walled magnesium alloy components with multiple inner ring ribs. The mold includes an upper mold and a lower mold. A punch pad is provided at the bottom of the upper mold, and a punch sleeve is provided at the bottom of the punch pad. The side of the punch sleeve is detachably connected to the upper mold via screw C. A lower pad is provided at the top of the lower mold, and an ejector rod is inserted inside the lower mold. A die pad block is provided at the top of the lower pad. The forming method includes the following steps: magnesium alloy ingot preparation, double-stage homogenization treatment, extrusion billet preparation, homogenized casting for large plastic deformation to obtain a hollow deformed billet with fine and uniform microstructure, and near-net-shape forming of the thin-walled component with multiple inner ring ribs. This invention can achieve one-pass integrated forming of thin-walled cabin components with complex structures such as multiple inner ring ribs and internal bosses. The prepared magnesium alloy cabin components have stable performance and low anisotropy.

Description

Technical Field

[0001] This invention belongs to the field of thin-walled light alloy forming technology, specifically relating to a near-net-shape forming mold and method for complex thin-walled magnesium alloy components with multiple inner ring ribs. Background Technology

[0002] High-performance magnesium alloy components play an important role in the lightweighting of aerospace equipment. Under effective load, the lighter the component, the greater the weight margin, which is more conducive to improving the mobility, long range and efficiency of the equipment.

[0003] To improve the effective loading coefficient, there is an urgent need for magnesium alloy complex variable cross-section thin-walled (the main wall thickness of the component is usually no more than 5mm) cabin components. From the perspective of forming process development, traditional machining, casting, and welding processes face bottlenecks such as low material utilization and low performance. To improve the refinement of forging blanks, multi-pass forming was adopted without considering the intrinsic material property of magnesium alloys, which is extremely sensitive to the number of heating times and heating temperature. This resulted in grain coarsening and the growth of second phase precipitation, leading to low forging performance and large variation, which could not meet the service performance requirements. Near-net-shape forming methods such as precision die forging, spinning, local loading, and superplastic forming provide solutions for the overall high-performance forming of thin-walled, ribbed, complex structural components.

[0004] Existing document CN113579132B discloses a precision rolling die and method for rectangular cross-section ring parts with external island bosses. The die includes a drive roller, a core roller, and a combined die set that can rotate actively. The drive roller or core roller can be fed linearly. The combined die set includes several segmented dies that can be enclosed in a circle, and an upper clamping plate and a lower clamping plate that clamp all the segmented dies together. The upper and lower clamping plates each have a core roller passage hole in their center. All the segmented dies, the upper clamping plate, and the lower clamping plate form an annular groove on their inner surfaces. However, this method cannot successfully form thin-walled cabin components, especially cabin components with thin-walled inner ring ribs (rib wall thickness not exceeding 5mm and protrusion height not exceeding 5mm). Summary of the Invention

[0005] This invention provides a near-net-shape forming mold and method for complex thin-walled magnesium alloy components with multiple inner ring ribs, which can at least prepare high-performance magnesium alloy components with complex structures such as multiple inner ring ribs and inner walls containing bosses.

[0006] The present invention adopts the following technical solution.

[0007] A near-net-shape forming mold for complex thin-walled magnesium alloy components with multiple inner ring ribs includes an upper mold plate and a lower mold plate. A punch pad is provided at the bottom of the upper mold plate, and a punch sleeve is provided at the bottom of the punch pad. The side of the punch sleeve is detachably connected to the upper mold plate via screw C. A lower pad is provided at the top of the lower mold plate, and an ejector rod is inserted inside the lower mold plate. A die pad block is provided at the top of the lower pad, and a die pressure ring is fitted on the outer side of the die pad block. The die pressure ring is detachably connected to the lower mold plate via screw A. A die shell is detachably installed at the top of the die pad block via screw B. A die pad plate is fixedly installed at the bottom inner side of the die shell. A segmented combined punch is threadedly connected to the top of the die pad, and a tapered punch mandrel is inserted inside the segmented combined punch.

[0008] In order to achieve near-net-shape forming of thin-walled magnesium alloy components more efficiently and smoothly, the segmented combined punch consists of four fan-shaped wedge-shaped punch modules and four wedge-shaped cuboid punch modules, with heating tubes inserted inside the fan-shaped wedge-shaped punch modules.

[0009] Furthermore, the outer side of the segmented combined punch is provided with a groove.

[0010] Furthermore, the tapered punch mandrel is mounted inside the punch sleeve via its own top frustum.

[0011] Furthermore, a clamp is also installed inside the punch sleeve.

[0012] Furthermore, the top of the ejector rod extends into the pre-reserved hole in the center of the die pad.

[0013] Furthermore, the lower periphery of the die pad has a protrusion, and the inner wall of the die pressure ring has a stepped portion, with the protrusion and the stepped portion mutually restricting each other.

[0014] A near-net-shape forming method for complex thin-walled magnesium alloy components with multiple inner ring ribs, comprising the following steps: S1: Preparation of magnesium alloy ingots to obtain cylindrical or square billets; S2: After the two-stage homogenization process, the beginning and end of the billet are cut off, and the surface oxide scale is removed by machining. S3: Preparation of extruded billets, homogenized casting for large plastic deformation, to obtain hollow deformed billets with fine and uniform structure; S4: Near-net-shape construction of thin-walled components with multiple inner ring ribs: ①Preparation before forming: Apply oil-based graphite to the working surface that comes into contact with the blank, and complete the mold assembly; ② During the forming process, the upper mold descends under the action of the independent power output shaft at the center of the press, supporting the inner hole of the hollow blank. The press moves downward as a whole, squeezing the hollow blank downward. The blank first flows along the upper and lower axial and radial directions of the cavity to complete the overall forming.

[0015] Beneficial effects: The solution of this invention enables one-pass integrated forming of thin-walled cabin components with complex structures such as multiple inner ring ribs and internal bosses. It effectively improves the fluidity and filling capacity of the billet, avoids the performance degradation of components caused by multi-pass heating deformation, and produces complex thin-walled magnesium alloy components with multiple inner ring ribs that exhibit stable performance and low anisotropy. In this invention, a heating tube is installed in the combined punch, which can supplement the temperature of the billet during the forming process, improving the fluidity and formability of the billet. The combined punch adopts a segmented design, with the shape of the multi-segment punch modules being curved surfaces with grooves, used to form the inner ring rib part of complex components. If there are complex structures such as bosses on the inner wall of the component, matching grooves can be set at the corresponding positions of the multi-segment punch modules to achieve integrated forming of complex structures such as inner ring ribs and bosses. After extrusion, the withdrawal of the conical punch mandrel provides sufficient space for the removal of the multi-segment wedge-shaped cuboid punch modules. After removing the multi-segment wedge-shaped cuboid punch modules, the sequential demolding of the segmented combined punch can be completed. More importantly, the solution of this invention can successfully form a cabin component with thin-walled inner ring ribs (the wall thickness of the ring ribs is no more than 5mm and the protrusion height is no more than 5mm), which can effectively prevent the thin-walled inner ring ribs from twisting and deforming. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the cross-sectional structure in the embodiment; Figure 2 This is a schematic diagram of the cross-sectional structure in the embodiment; Figure 3 This is a schematic diagram of the tapered punch mandrel structure in the embodiment; Figure 4 This is a schematic diagram of the segmented combined punch structure in the embodiment; Figure 5 This is a top view schematic diagram of the segmented combined punch structure in the embodiment; Figure 6 This is a schematic diagram of the cross-sectional structure of the wedge-shaped cuboid convex module in the embodiment.

[0017] In the figure: 1-Die pad, 2-Ejector rod, 3-Lower pad, 4-Die pressure ring, 5-Die pad block, 6-Die shell, 7-Segmented combined punch, 8-Lower template, 9-Clamp, 10-Punch sleeve, 11-Punch pad, 12-Upper template, 13-Screw A, 14-Screw B, 15-Screw C, 16-Conical punch mandrel, 71-Fan-shaped wedge punch module, 72-Wedge-shaped cuboid punch module, 73-Heating tube. Detailed Implementation

[0018] The technical solutions 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. Example

[0019] Combination Figure 1 , Figure 2 As shown, a near-net-shape forming mold for complex thin-walled magnesium alloy components with multiple inner ring ribs includes an upper template 12 and a lower template 8. A punch pad 11 is provided at the bottom of the upper template 12, and a punch sleeve 10 is provided at the bottom of the punch pad 11. A clamp 9 is also installed inside the punch sleeve 10. The side of the punch sleeve 10 is detachably connected to the upper template 12 by screws C15.

[0020] Please see Figure 1-2 The lower template 8 has a lower backing plate 3 on its top, and an ejector rod 2 is inserted inside the lower template 8. The top of the ejector rod 2 extends into the pre-drilled hole in the center of the die backing plate 1. The lower backing plate 3 has a die backing block 5 on its top, and a die pressure ring 4 is fitted on the outside of the die backing block 5. The lower outer periphery of the die backing block 5 has a protrusion, and the inner wall of the die pressure ring 4 has a stepped portion. The protrusion and the stepped portion restrict each other. The die pressure ring 4 is detachably connected to the lower template 8 by screws A13.

[0021] Please see Figure 1-6 The top of the die pad 5 is detachably mounted with a die shell 6 via screw B14. The bottom of the die shell 6 is fixedly mounted with a die pad 1. The top of the die pad 1 is threadedly connected with a split-type combined punch 7. The outer side of the split-type combined punch 7 is provided with a groove for forming the inner ring ribs and complex boss parts of complex components. The split-type combined punch 7 is composed of four fan-shaped wedge-shaped punch modules 71 and four wedge-shaped cuboid punch modules 72. Heating tubes 73 are inserted inside the fan-shaped wedge-shaped punch modules 71, which effectively supplements the heat loss of the billet during the extrusion process and improves the flowability and filling capacity of the billet.

[0022] Please see Figure 1-6 The inside of the segmented combined punch 7 is a tapered punch mandrel 16, which is installed inside the punch sleeve 10 through its own top truncated cone. After extrusion, the tapered punch mandrel 16 is removed, providing sufficient space for the demolding of the four wedge-shaped cuboid punch module 72, thus completing the sequential demolding of the segmented combined die.

[0023] A near-net-shape forming method for complex thin-walled magnesium alloy components with multiple inner ring ribs, comprising the following steps: S1: Preparation of magnesium alloy ingots to obtain cylindrical or square billets; S2: After the two-stage homogenization process, the beginning and end of the billet are cut off, and the surface oxide scale is removed by machining. S3: Preparation of extruded billets, homogenized casting for large plastic deformation, to obtain hollow deformed billets with fine and uniform structure; S4: Near-net-shape construction of thin-walled components with multiple inner ring ribs: ①Preparation before forming: Apply oil-based graphite to the working surface that comes into contact with the blank, and complete the mold assembly; ② Forming process: The upper mold descends under the action of the independent power output shaft of the press center, supporting the inner hole of the hollow blank. The press as a whole descends and squeezes the hollow blank downwards. The blank first flows along the upper and lower axial and radial directions of the cavity to complete the overall forming.

[0024] Implementation Case 1: A complex thin-walled magnesium alloy component with multiple inner ring ribs (a thin-walled cabin component made of Mg-Gd-Y-Zr, with a main wall thickness of 4.5 mm, two spaced inner ring ribs with a thickness of 4 mm and a protrusion height of 3 mm) formed using the aforementioned forming method. Specific performance data are shown in Tables 1 and 2 below. Table 1. Mechanical properties at room temperature Table 2 High-Temperature Mechanical Properties 2C-2302-Axial 1# 250 254 208 19.5 2C-2302-Axial 2# 250 286 236 22.0 2C-2302-Axial 3# 250 282 230 16.5 2C-2302-Tangential 1# 250 222 179 19.0 2C-2302-Tangential 2# 250 214 176 17.0 2C-2302-Tangential 3# 250 195 165 17.0

[0025] Implementation Case 2: A complex thin-walled magnesium alloy component with multiple inner ring ribs (a thin-walled cabin component made of Mg-Gd-Y-Zr, with a main body wall thickness of 5mm, and two spaced inner ring ribs with a thickness of 3.5mm and a protrusion height of 2.5mm) formed using the aforementioned forming method. Specific performance data are shown in Tables 3 and 4 below. Table 3 Room Temperature Mechanical Properties Table 4 High-Temperature Mechanical Properties 4C-2302-Axial 1# 250 273 215 18.5 4C-2302-Axial 2# 250 307 243 19.0 4C-2302-Axial 3# 250 313 249 21.0 4C-2302-Tangential 1# 250 312 236 19.0 4C-2302-Tangential 2# 250 282 231 21.0 4C-2302-Tangential 3# 250 295 233 20.0

[0026] By adopting the scheme in the embodiment, a single-pass forming of a complex thin-walled component can be achieved, avoiding the loss of magnesium alloy properties caused by heating during multiple forming processes. This is beneficial for preserving the uniform fine-grained structure after strong plastic deformation, improving the uniformity of performance, and reducing performance jumps in different directions.

[0027] In this embodiment, the combined punch adopts a segmented design. The outer shape of the 8-segment punch is a curved surface with grooves, which is used to form the inner ring rib part of complex components. If there are complex structures such as bosses on the inner wall of the component, matching grooves can be set at the corresponding positions of the 8-segment punch to realize the integrated forming of complex structures such as inner ring ribs and bosses. The 4-segment fan-shaped wedge punch 71 has a pre-embedded heating tube 73, which effectively supplements the heat loss of the billet during the extrusion process, improves the flowability and filling capacity of the billet. After extrusion, the withdrawal of the conical punch mandrel 16 provides sufficient space for the removal of the 4-segment wedge-shaped cuboid punch 72. After removing the 4-segment wedge-shaped cuboid punch 72, the sequential demolding of the segmented combined punch 7 can be completed.

[0028] In this embodiment, due to the use of the aforementioned mold with a specific structure, the flow field of the blank during the forming process is more uniform and smoother. The blanks in the same area, especially the blanks used to form the ring ribs, have a shorter flow path in the circumferential direction, which can smoothly form a cabin component with thin-walled inner ring ribs (ring rib wall thickness not greater than 5mm and protrusion height not greater than 5mm). This can effectively prevent the thin-walled inner ring ribs from twisting and deforming. In this embodiment, the thin-walled inner ring ribs of the formed thin-walled cabin component all meet the design requirements.

[0029] In summary, the near-net-shape forming mold and method for complex thin-walled magnesium alloy components with multiple inner ring ribs can achieve one-pass integrated forming of thin-walled cabin components with complex structures such as multiple inner ring ribs and internal bosses. It can effectively increase the billet temperature, improve the billet's fluidity and filling capacity, and avoid the performance degradation of components caused by multi-pass heating deformation. The prepared magnesium alloy cabin components have stable performance and low anisotropy.

Claims

1. A near-net-shape forming mold for complex thin-walled magnesium alloy components with multiple inner ring ribs, comprising an upper mold plate (12) and a lower mold plate (8), characterized in that: The upper template (12) is provided with a punch pad (11) at the bottom, and a punch sleeve (10) is provided at the bottom of the punch pad (11). The side of the punch sleeve (10) is detachably connected to the upper template (12) by screw C (15). The lower template (8) is provided with a lower pad (3) at the top. An ejector rod (2) is inserted inside the lower template (8). A die pad block (5) is provided at the top of the lower pad block (3). A die pressure ring (4) is fitted on the outside of the die pad block (5). The die pressure ring (4) is detachably connected to the lower template (8) by screw A (13). A die shell (6) is detachably installed on the top of the die pad block (5) by screw B (14). A die pad plate (1) is fixedly installed on the inner bottom of the die shell (6). The top of the die pad plate (1) is threaded with The split-type combined punch (7) has a conical punch mandrel (16) inserted inside it; the split-type combined punch (7) is composed of four fan-shaped wedge-shaped punch modules (71) and four wedge-shaped cuboid punch modules (72), and heating tubes (73) are inserted inside the fan-shaped wedge-shaped punch modules (71) and the wedge-shaped cuboid punch modules (72); the split-type combined punch (7) has a groove on its outer side; the conical punch mandrel (16) is installed inside the punch sleeve (10) through its own top frustum; the conical punch mandrel (16) is installed inside the punch sleeve (10) through its own top frustum; a clamp (9) is also installed inside the punch sleeve (10); the press moves downward as a whole, extruding the hollow blank downward, and the blank first flows along the upper and lower axial and radial directions of the cavity to complete the overall forming.

2. The near-net-shape forming mold for complex thin-walled magnesium alloy components with multiple inner ring ribs according to claim 1, characterized in that: The top of the ejector rod (2) extends into the pre-reserved hole in the center of the die pad (1).

3. The near-net-shape forming mold for complex thin-walled magnesium alloy components with multiple inner ring ribs according to claim 1, characterized in that: The lower periphery of the die pad (5) has a protrusion, and the inner wall of the die pressure ring (4) has a stepped portion, with the protrusion and the stepped portion mutually restricting each other.

4. A forming method using a near-net-shape forming mold for complex thin-walled magnesium alloy components with multiple inner ring ribs as described in any one of claims 1-3, characterized in that, The steps are as follows: S1: Preparation of magnesium alloy ingots to obtain cylindrical or square billets; S2: After the two-stage homogenization process, the beginning and end of the billet are cut off, and the surface oxide scale is removed by machining. S3: Preparation of extruded billets, homogenized casting for large plastic deformation, to obtain hollow deformed billets with fine and uniform structure; S4: Near-net-shape construction of thin-walled components with multiple inner ring ribs: ① Pre-forming preparation: Apply oil-based graphite to the working surface that comes into contact with the blank, and complete the mold assembly; ② During the forming process, the upper mold descends under the action of the independent power output shaft at the center of the press, supporting the inner hole of the hollow blank. The press moves downward as a whole, squeezing the hollow blank downward. The blank first flows along the upper and lower axial and radial directions of the cavity to complete the overall forming.

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