Metal plate creep forming device

Abstract

The invention relates to the technical field of metal plate processing, in particular to a creep forming device for a metal plate. The device comprises an upper die fixing structure, a lower male die, a plurality of middle dies and an upper female die, and meanwhile, cooling channels are formed in the dies, so that the dies can be cooled; the middle die is a cambered surface die, and the radian of the adjacent cambered surfaces of different dies is the same, the ratio of the curvature radius of the upper cambered surface to the curvature radius of the lower cambered surface of the same middle die is larger than 1 and smaller than 1.5, and the ratio of the concave arc height to the convex arc height is larger than 0.5 and smaller than 1; the two ends of each structure are connected in a penetrating mode through supporting rods to achieve the fixing effect, and thin plates are convenient to take through cooperation of horizontal through holes in the two ends of the middle mold and limiting rods. The forming device disclosed by the invention is beneficial to realizing batch treatment of plates with different radians, is stable in structure, convenient to use and applicable to any box-type heat treatment furnace, avoids the period and the cost of constructing the device, can also be used for performing cryogenic forming by utilizing a cooling channel, and is wide in application range.

Description

Technical Field

[0001] The present invention relates to the technical field of metal sheet processing, and particularly relates to a metal sheet creep forming device. Background Art

[0002] The structural components of aerospace aircraft are continuously developing towards lightweight, and new directions for their preparation methods have also been proposed: using hot pressing creep forming to prepare the required arc-shaped structural components from thin plates. Generally, when the deformation of the plate is small, it is still in the elastic deformation range of the metal. However, through a method combined with heat treatment, plastic deformation can also occur under the condition that the stress does not reach the yield strength, achieving the required shape.

[0003] Currently, the devices using creep forming usually adopt vacuum hot pressing conditions to achieve the forming control of large-size aluminum alloy plates. For example, a device for vacuum creep aging forming of aluminum alloy components with complex curvature disclosed in Chinese Patent CN208116533U. Some of the existing vacuum hot pressing devices use fixed molds and open molds according to the required part morphology. This method can only deform mature fixed parts. Once there is any modification, the entire mold needs to be changed. Some technologies have been optimized, using single-sided or double-sided to push rod arrays to achieve the control of different deformation shapes. For the existing vacuum hot pressing devices, on the one hand, vacuum hot pressing cannot use a conventional box-type heat treatment furnace and requires the construction of a special vacuum hot pressing tank device, with high cycle and cost, complex operation, and certain risks. On the other hand, the current designs only consider processing a single aluminum alloy thin plate specimen at a time and cannot achieve simultaneous multi-piece and multi-arc deformation. If multiple single-processing devices are stacked for use, there is a problem of poor stability.

[0004] Generally speaking, the above methods are suitable for thin plate parts that have been relatively maturely studied for single processing verification, but are not suitable for batch evaluation and analysis of plates and process exploration during the research and development process. Therefore, it is necessary to develop a mold with universality, avoid the construction of special equipment, and the mold processing is simple, the device operation is simple, the experimental cycle is short, and high-efficiency creep forming of multiple thin plates can be carried out under the same conditions. Summary of the Invention

[0005] In order to better adapt to the hot pressing creep forming of a conventional box-type heat treatment furnace in the laboratory, and at the same time improve the forming effect and stability of large-curvature plates, the present invention proposes a metal sheet creep forming device, and the specific scheme is as follows:

[0006] A creep forming device for metal sheets, characterized in that it successively includes, from top to bottom: an upper die fixing structure, at least two intermediate dies, and an upper female die. Vertical through holes are provided at both ends of the upper die fixing structure, the intermediate dies, and the upper female die. Support rods penetrate through the vertical through holes and are fixed by nuts. Cooling channels are provided on the upper die fixing structure, the intermediate dies, and the upper female die. The middle parts of the upper and lower surfaces of the intermediate dies and the middle part of the upper surface of the upper female die are all arc surfaces that are bent downward and have the same horizontal length. The radian of two adjacent arc surfaces between the intermediate dies and between the intermediate die and the upper female die is the same (that is, the radian of two adjacent arc surfaces between different dies or structures is the same). And the ratio of the curvature radius of the upper arc surface to the curvature radius of the lower arc surface of the same intermediate die is greater than 1 and less than 1.5, and the ratio of the concave arc height of the upper arc surface to the convex arc height of the lower arc surface is greater than 0.5 and less than 1. Horizontal through holes are symmetrically provided on the side faces at both ends of the intermediate die. The horizontal through holes penetrate through the vertical through holes, and the depth of the horizontal through holes is greater than the farthest distance from the vertical through hole to the side face. A plurality of horizontal holes are symmetrically provided on the left and right support rods, and the diameter of the horizontal through holes is not greater than the diameter of the horizontal holes. A limit rod is further included, and the outer diameter of the limit rod matches the diameter of the horizontal through hole.

[0007] Further, a lower male die is further included. The lower male die is located between the upper die fixing structure and the uppermost intermediate die. The middle part of the lower surface of the lower male die, the middle parts of the upper and lower surfaces of the intermediate die, and the middle part of the upper surface of the upper female die are all arc surfaces that are bent downward and have the same horizontal length. The upper surface of the lower male die is a horizontal plane, and the radian of two adjacent arc surfaces between the lower male die, the intermediate die, and the upper female die is the same.

[0008] Further, the curvature radius of the arc surface on the lower surface of the lower male die is less than or equal to 1.15 times the horizontal length of the arc surface, and the convex arc height is greater than or equal to 0.1 times its curvature radius.

[0009] Further, the curvature radius of the arc surface on the upper surface of the upper female die is greater than 0.5 times the horizontal length of the arc surface, and the concave arc height is less than its curvature radius.

[0010] Further, the middle part of the bottom surface of the upper female die is lower than both ends, and the horizontal length of the middle lower bottom surface is not less than the horizontal length of the upper surface arc surface.

[0011] Further, counterbored holes matching the size of the support rods are provided at both ends of the upper female die.

[0012] Further, the cooling channels are channels with a circular cross-section, and a plurality of the cooling channels are provided along the width direction of the lower male die, the plurality of intermediate dies, and the upper female die. The cooling channels are applicable to liquid or gaseous cooling media, and the same or different cooling media can be used simultaneously, and the medium temperature is not limited within the range that the device can withstand.

[0013] Advantages of the present invention: The creep forming device for metal sheets of the present invention does not have a vacuum chamber and does not need to be directly connected to a heating source. It can be directly placed in various box-type heat treatment furnaces commonly used in laboratories for heat treatment. At the same time, the curvature of the mold in this device gradually increases from top to bottom. While utilizing the gravity effect, the upper mold with a certain curvature correspondingly reduces the force on the lower layer at the end, which is beneficial to the forming effect of sheets with large curvature processing, and can significantly improve the overall stability of the device. This device can batch process multiple and various curvature sheets, facilitating the evaluation of controlled variables for batch thin plate parts in the laboratory. Moreover, both ends of the intermediate mold and the support rods of this device are provided with matching horizontal holes, which are used in conjunction with the limiting rods. After the intermediate mold is moved upward and limited, the thin plate can be taken or placed without disassembling the intermediate template one by one, which is convenient for operation and easy to manage. In addition to hot pressing and forming in combination with a box-type heat treatment furnace, this device can also achieve cryogenic forming by introducing a cooling medium such as liquid nitrogen into the cooling channel, and has a broader prospect in application. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The following further describes the embodiments of the present invention with reference to the accompanying drawings, where:

[0015] Figure 1 The front view of the creep forming device for metal sheets in Embodiment 1 of the present invention is shown;

[0016] Figure 2 The schematic diagram of a specific arc surface in the device of the present invention is shown;

[0017] Figure 3 The top view and side view of the counterbore at both ends of the upper die in the device of the present invention are shown;

[0018] Figure 4 The top view and side view of the vertical through holes at both ends of the intermediate mold in the device of the present invention are shown;

[0019] Figure 5 The schematic diagram of the creep forming device for metal sheets in Embodiment 2 of the present invention is shown;

[0020] Figure 6 The partial schematic diagram of the limiting structure of the intermediate mold of the creep forming device for metal sheets in the embodiment of the present invention is shown;

[0021] Figure 7 Shows Figure 6 The side view of the circled part.

[0022] Wherein: 1 - upper die fixing structure, 2 - upper female die, 3 - lower male die, 4 - intermediate mold, 5 - support rod, 6 - nut, 7 - cooling channel, 8 - counterbore, 9 - vertical through hole, 10 - aluminum alloy thin plate, 11 - limiting rod, 12 - limiting rod head, 13 - horizontal through hole, 14 - horizontal hole. Detailed implementation mode

[0023] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below through specific embodiments in conjunction with the accompanying drawings. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0024] Embodiment 1

[0025] As shown in the attached Figure 1 figures, a creep forming device for metal sheets includes, from top to bottom in sequence: an upper die fixing structure 1, a lower punch 3, four intermediate dies 4, and an upper die 2. Vertical through holes 9 are symmetrically machined at both ends of the upper die fixing structure 1, the lower punch 3, the four intermediate dies 4, and the upper die 2. After a support rod 5 passes through the vertical through holes 9, it is fixed at the top by a nut 6. The vertical through holes 9 at both ends of the support rod 5 are not threaded, and the diameter difference between the vertical through holes 9 and the diameter of the support rod 5 is ≤ 1 mm. The support rod 5 is a bolt rod to ensure the smooth assembly, fixation, and disassembly of the entire device. The upper die fixing structure 1 is located at the top of the entire device and is a plate with flat upper and lower surfaces, which is used for fixing the top of the die of the entire device to ensure the stability of the entire device. The lower punch 3 is located below the upper die fixing structure 1, and the two structures are closely attached to ensure the stability of the device fixation. The upper die 2 is located at the bottom of the entire device and mainly plays a supporting role. Its bottom surface is a stepped plane to ensure the stability of the entire device. Countersunk holes 8 without threads are provided at both ends of the upper die 2. The support rod 5 is used to penetrate other die structures for connection and fixation. The upper half of the countersunk hole 8 has the same diameter as the vertical through holes 9 in other parts, and the bottom hole diameter is an enlarged hole diameter, which is used to house the bolt head of the support rod 5 and matches the size of the bolt head. The purpose of this setting is to hide the bolt head part and ensure that there are no protruding components on the bottom platforms at both ends of the upper die 2. The middle part of the bottom surface of the upper die 2 is lower than both ends (i.e., stepped). The horizontal length of the middle part with a lower bottom surface is not less than the horizontal length of the upper surface arc. That is, when the entire device is placed horizontally, the middle part of the bottom surface of the upper die 2 is the contact surface, and both ends are suspended. Under this condition, when the entire device needs to be moved as a whole, when using a crane for moving, both ends can provide a fixed position for the binding belt, or when using a forklift for moving, it can provide a supporting position for the forklift arm.

[0026] The middle part of the lower surface of the lower punch 3, the middle parts of the upper and lower surfaces of the intermediate die 4, and the middle part of the upper surface of the upper die 2 are all downwardly curved arc surfaces with the same horizontal length. The radian of two adjacent arc surfaces between the lower punch 3, the intermediate die 4, and the upper die 2 is the same. As shown in the attached Figure 2 figures, the radius of curvature of the arc is R, the height of the convex or concave arc is h, and the horizontal length of the arc surface is L. Among them, the parameters of the lower punch 3 are R B0 and h B0 , and the parameters of the upper die 2 are R T0 and h T0, the radius of curvature of the upper arc surface of the same intermediate die 4 is R T , the concave arc height is h T , the radius of curvature of the lower arc surface is R B , the convex arc height is h B , satisfying 1 < R T / R B <1.5, 0.5 < h T / h B <1. Also satisfy R T0 >L / 2, h T0 <R T0 , R B0 ≤1.15L, h B0 ≥0.1R B0 。In this embodiment, the length L of all the above arc surfaces is 1m, and the h of the lower arc surface of the lower convex die 3 B0 is 0.3m, the h of the upper concave die 2 T0 is 0.5m, and the four intermediate dies 4 from top to bottom: the h of the first one T is 0.3m, h B is 0.35m; the h of the second one T is 0.35m, h B is 0.40m; the h of the third one T is 0.40m, h B is 0.45m; the h of the fourth one T is 0.45m, h B is 0.50m.

[0027] Cooling channels 7 are provided on the upper die fixing structure 1, the lower convex die 3, the four intermediate dies 4 and the upper concave die 2. The cooling channels 7 are channels with a circular cross-section, and a plurality of cooling channels 7 are provided along the width direction of the lower convex die 3, the four intermediate dies 4 and the upper concave die 2 (each cooling channel is provided along the longitudinal direction). The cooling rate can be controlled by using this cooling channel, avoiding long waiting for the die to cool after the experiment is completed. Different liquid or gaseous cooling media can be used according to the experimental needs. Similarly, there is no conflict relationship between the cooling structures of each structure, and the same or different cooling media can be used at the same time. It should be noted that within the range that the device can withstand, the medium temperature is not restricted.

[0028] The upper die fixing structure 1, the upper concave die 2, the lower convex die 3 and the intermediate die structure 4 of the whole device all adopt the same horizontal length and width dimensions, the horizontal length of the middle arc part is the same, and the hole opening positions at the left and right ends are the same to ensure the fitting of the device with the part during use.

[0029] Both side faces at the two ends of the four intermediate dies 4 are symmetrically provided with the same horizontal through holes 13. The horizontal through holes 13 penetrate through the vertical through holes 9. The diameter of the horizontal through holes 13 is smaller than that of the vertical through holes 9. The depth of the horizontal through holes 13 is greater than the farthest horizontal distance from the vertical through holes 9 to the side face of the intermediate die 4. A plurality of horizontal holes 14 are uniformly formed in the support rod. The diameter of the horizontal through holes 13 is not greater than that of the horizontal holes 14. It further includes a limiting rod 11. The outer diameter of the limiting rod 11 matches the diameter of the horizontal through holes 13. A limiting rod head 12 perpendicular to the limiting rod 11 can be provided at the end of the limiting rod 11. After the forming is completed, lift a certain intermediate die 4 and the die thereon, so that the two horizontal through holes 13 on both sides of the intermediate die 4 are respectively aligned with a horizontal hole 14. Insert the limiting rod 11 into the horizontal through hole 13. At the same time, the limiting rod 11 penetrates through the horizontal hole 14 to suspend and limit the intermediate die 4. At this time, the formed thin plate can be taken out, and at the same time, the next thin plate to be processed can be put in. This structural setting enables the device to take the thin plate without disassembling the multiple dies layer by layer, saving space and being convenient to use.

[0030] Five groups of 5xxx aluminum alloy thin plates 10 with a thickness of 1.5 mm are respectively placed between the lower punch 3 and the intermediate die 4, between multiple intermediate dies 4, and between the intermediate die 4 and the upper die 2 for hot compression creep forming. The heat preservation condition is 200 °C for 5 h. After the deformation is completed, place the die in the room temperature air environment and slowly cool it to room temperature, then take out the thin plate part, and evaluate the completed thin plate part. The arc of the plate type does not twist or spring back.

[0031] Another five groups are deformed under the same die, the same deformation conditions, and the same aluminum alloy thin plates 10. After the deformation is completed, cool them through circulating water in the cooling system, and take them out after cooling to room temperature. The obtained metal plate type effect is the same as that of the above-mentioned slow cooling.

[0032] Another five groups are deformed under the same die and the same aluminum alloy thin plates 10 under different deformation conditions: after placing the 5xxx aluminum alloy thin plate with a thickness of 1.5 mm in the die, without heating and heat preservation, directly introduce liquid nitrogen into the cooling pipeline for cryogenic forming test. After the deformation is completed, take out the thin plate part after returning to room temperature, and its deformation effect is good.

[0033] Embodiment 2

[0034] As shown in the Figure 5 accompanying figure, a creep forming device for metal plates, the device structure does not include the lower punch 3. The upper die fixing structure 1 is directly in contact with the topmost intermediate die 4. There are three layers of intermediate dies in total. The structural parameters of the intermediate dies are the same as those of the adjacent three intermediate dies in Embodiment 1, and other structures are also the same as those in Embodiment 1.

[0035] Three groups of 5xxx aluminum alloy thin plates 10 with a thickness of 1.5 mm are respectively placed between the middle dies 4 and between the middle die 4 and the upper female die 2 for hot pressing creep forming. Under the condition of heat preservation at 200 °C for 5 h, after the deformation is completed, the die is placed in the room temperature air environment and slowly cooled to room temperature, and then the thin plate part is taken out. The thin plate part that has been completed is evaluated, and the arc of the plate shape does not twist or spring back.

[0036] Some exemplary embodiments of the present invention are described above. It can be understood that the above embodiments are only used to explain the present invention and do not constitute a limitation on the protection scope of the present invention. The features in these embodiments can be recombined in a suitable manner, and the solutions obtained thereby are still within the protection scope required by the present invention. Based on the above embodiments, all other embodiments obtained by those skilled in the art without creative efforts, that is, all modifications, equivalent replacements, improvements, etc. made within the spirit and principle of this application, fall within the protection scope required by the present invention.

Claims

1. A metal sheet creep forming device, characterized in that: The invention comprises, from top to bottom, an upper die fixing structure (1), at least two intermediate dies (4) and an upper die (2); both ends of the upper die fixing structure (1), the intermediate dies (4) and the upper die (2) are provided with vertical through holes (9); a support rod (5) passes through the vertical through holes (9) and is fixed by a nut (6); a cooling channel (7) is provided on the upper die fixing structure (1), the intermediate dies (4) and the upper die (2); the middle parts of the upper and lower surfaces of the intermediate dies (4) and the middle part of the upper surface of the upper die (2) are all curved surfaces that are bent downward and have the same horizontal length; the curvature of the two adjacent curved surfaces between the intermediate dies (4) and between the intermediate dies and the upper die (2) is the same; and the same intermediate dies (4) are provided with a plurality of cooling channels (7); ) has a ratio of a curvature radius of the upper arc surface to a curvature radius of the lower arc surface greater than 1 and less than 1.5, and a ratio of a concave arc height of the upper arc surface to a convex arc height of the lower arc surface greater than 0.5 and less than 1; horizontal through holes (13) are symmetrically provided on the side surfaces at both ends of the intermediate mold (4), the horizontal through holes (13) pass through the vertical through holes (9), the depth of the horizontal through holes (13) is greater than the farthest distance from the vertical through holes (9) to the side surfaces, and a plurality of horizontal holes (14) are symmetrically provided on the left and right support rods (5), the diameter of the horizontal through holes (13) is not greater than the diameter of the horizontal holes (14); and a limiting rod (11) is also included, the outer diameter of the limiting rod (11) matches the diameter of the horizontal through hole (13).

2. A metal sheet creep forming device according to claim 1, characterized in that: It also includes a lower punch (3), which is located between the upper mold fixing structure (1) and the uppermost intermediate mold (4), the middle of the lower surface of the lower punch (3) and the middle of the upper and lower surfaces of the intermediate mold (4) and the middle of the upper surface of the upper die (2) are all curved surfaces that are bent downward and have the same horizontal length, the upper surface of the lower punch (3) is a horizontal plane, and the curvature of adjacent curved surfaces of the lower punch (3), the intermediate mold (4) and the upper die (2) is the same.

3. A metal sheet creep forming device according to claim 2, characterized in that: The curvature radius of the arc surface of the lower surface of the lower punch (3) is less than or equal to 1.15 times the horizontal length of the arc surface, and the height of the convex arc is greater than or equal to 0.1 times its curvature radius.

4. The metal sheet creep forming device according to claim 1, characterized in that: The curvature radius of the arc surface on the upper surface of the upper concave die (2) is greater than 0.5 times the horizontal length of the arc surface, and the height of the concave arc is less than its curvature radius.

5. The metal sheet creep forming device according to claim 1, characterized in that: The middle part of the bottom surface of the upper concave die (2) is lower than the two ends, and the horizontal length of the middle low bottom surface is not less than the horizontal length of the upper surface arc.

6. The metal sheet creep forming device according to claim 1, characterized in that: Countersunk holes (8) matching the size of the support rod (5) are provided at both ends of the upper die (2).

7. The metal sheet creep forming device according to claim 1, characterized in that: The cooling channel (7) is a channel with a circular cross-section, and a plurality of cooling channels (7) are provided along the width direction of the lower punch (3), the plurality of intermediate molds (4) and the upper die (2).

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