Method for manufacturing aluminum alloy thin-wall part through hot shape correction of rubber bag after sheet metal forming

Abstract

The invention discloses a method for manufacturing an aluminum alloy thin-wall part through hot shape correction of a rubber bag after sheet metal forming. The method comprises the steps that firstly, an aluminum alloy thin-wall part blank is obtained through sheet metal forming; secondly, the blank is subjected to solution treatment; thirdly, the blank obtained after solid solution treatment is put into a refrigerator to be stored; fourthly, the rigid mold, the rubber bag and the like are installed on a press machine, overall heating is conducted, and the temperature is kept stable; fifthly, the blank obtained after solid solution is rapidly placed above a hot-state rigid mold, and positioning of the rigid mold and the blank is completed; 6, quickly closing the die, pumping hydraulic oil into the rubber bag, and increasing the pressure of the press machine to the set pressure; seventhly, the rubber bag extrudes the blank to enable the blank to be tightly attached to the rigid mold, and the mold temperature is transmitted to the blank; 8, under the combined action of high pressure and a thermal field, the aluminum alloy is subjected to aging strengthening and stress relaxation, and springback is reduced; 9, unloading the pressure of the rubber bag and the hydraulic machine; and 10, opening the press machine to take out the blank, and uniformly cooling in a cooling tool to obtain a thin-wall part finished product.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of aluminum alloy hot forming, and particularly relates to a method for preparing an aluminum alloy thin-walled part by adopting rubber bag hot correction after sheet metal forming. BACKGROUND

[0002] Aluminum alloys are widely used for important parts such as aircraft inlet lip and rocket tank in aerospace. The main uses of 2 series and 7 series solid solution age treatment aluminum alloys include aerospace, high-speed train and automobile parts, etc. The aluminum alloys have high tensile strength and fatigue strength, and are suitable for parts that bear high stress, such as aircraft flap cabin sections, aileron cabin wall plates and other complex curvature thin-walled parts. The aluminum alloys have good machinability, and can be formed into various shaped parts through rolling, extrusion and other processes. The rubber bag forming method has the advantages of semi-die forming, simple forming die and high forming precision, and is widely used in the field of aerospace manufacturing.

[0003] The aluminum alloy rubber bag forming still has the following problems: due to high elastic deformation ratio and insufficient plastic deformation, uneven internal stress distribution will be caused, and local compression buckling instability will be caused, and uneven bulging defects will be formed. In addition, although the rubber bag forming has smaller springback than traditional stamping, there is still springback deformation problem for complex parts, and subsequent correction is still needed. In the prior art, a process method for controlling deformation of an aluminum alloy thin-walled member in a closed cavity is disclosed, which is by analyzing the stress condition of rubber bag forming, splitting the forming process, and verifying and correcting. In the prior art, a model is designed by using process compensation and springback compensation, and the final process model with springback is used to determine the expanded blank. However, this method is complex in forming process and is cold forming of rubber bag, and still cannot completely eliminate the problem of residual internal stress, and still needs subsequent heat treatment and organization regulation, which is complex and easy to cause low surface quality and low yield of the parts. Furthermore, in the rubber bag forming process of the heat treatable aluminum alloy thin-walled part, heat treatment is needed after forming to improve the strength, and the heat treatment deformation causes serious size distortion and overage. SUMMARY

[0004] The present application proposes a method for preparing an aluminum alloy thin-walled part by adopting rubber bag hot correction after sheet metal forming, aiming at the above problems. The aluminum alloy thin-walled part blank after sheet metal forming solid solution treatment is subjected to age hardening treatment. The rubber bag hot correction is simultaneously performed, and the process advantages of controlling shape and property of complex aluminum alloy thin-walled part forming are simultaneously achieved.

[0005] The above technology of the present application can be processed in the following steps: Step one, using the method of progressive roll forming, deep drawing and other sheet metal forming to form the whole aluminum alloy thin-walled part, and obtaining the aluminum alloy thin-walled part blank; Step two, performing solid solution treatment on the aluminum alloy thin-walled part blank after sheet metal forming; Step three, the solution after the new quenching state aluminum alloy thin-walled part blank into the freezer for storage; Step four, the rigid mold and rubber bag are installed on the press, and the rigid mold, rubber bag, heat-resistant hydraulic oil in the rubber bag, etc. are heated to the aluminum alloy hot correction and aging temperature by high temperature furnace, hot oil or heating rod, etc. The temperature is kept stable. Step five, raise the press, open the rigid mold, quickly place the new quenching state aluminum alloy thin-walled part blank in the hot rigid mold, and complete the positioning of the rigid mold and the aluminum alloy thin-walled part blank by using positioning pins and clamping positioning blocks. Step six, quickly close the mold, pump heat-resistant hydraulic oil into the rubber bag, and simultaneously increase the pressure of the press to make the rubber bag and the hydraulic press simultaneously increase the pressure to the set pressure. Step seven, the rubber bag expands and extrudes the aluminum alloy thin-walled part blank, forcing the aluminum alloy thin-walled part blank to tightly adhere to the rigid mold, while deforming, the aluminum alloy thin-walled part blank is heated to the aging temperature and performs long pressure retention. Step eight, under the action of high pressure and high temperature of the rubber bag, the aluminum alloy thin-walled part blank deforms, tightly adheres to the mold, and simultaneously strengthens and relaxes the stress, thereby improving the strength and forming precision. Step nine, simultaneously unload the pressure of the rubber bag and the hydraulic press to zero, raise the press, and the rubber bag returns to the initial position. Step ten, take out the aluminum alloy thin-walled part blank and place it in a cooling tool to cool evenly to room temperature to obtain a qualified aluminum alloy thin-walled part.

[0006] Further, in step one, the aluminum alloy thin-walled part blank is prepared by gradually rolling, deep drawing forming sheet metal forming method.

[0007] Further, in step two, the solid solution treatment temperature is 470-550℃, and the holding time is about 30-90min according to the thickness and structure of the aluminum alloy thin-walled part blank. The part is immediately quenched in water after taking out.

[0008] Further, in step four, the rigid mold, rubber bag and heat-resistant hydraulic oil are heated and continuously heat-treated as a whole, and kept at the aging temperature range of the aluminum alloy, so that the aluminum alloy part can be simultaneously aged during hot correction.

[0009] Further, the aging temperature of the aluminum alloy is 160-220℃.

[0010] Further, in step six, the heat-resistant hydraulic oil pressure is 5-200MPa, and the holding and pressure retention time is 1-24h.

[0011] Further, the step seven is: the rubber bag elastic modulus is 1.2-1.4 GPa, and the Poisson's ratio is 0.48-0.5.

[0012] Further, the rigid mold is: the male die is fixed on the rubber bag lower die, and the positioning of the male die and the rubber bag lower die is completed by the positioning pin, and the positioning and sealing of the male die and the rubber bag upper die are completed by the clamping positioning block; in the step three, the aluminum alloy thin-walled part after solid solution is placed above the male die, wherein the rubber bag serves as the female die, and finally the rubber bag upper die and the rubber bag lower die are closed.

[0013] The beneficial effects of the present application are: I. The combination of solid solution and aging heat treatment and rubber bag heat shaping can save the subsequent aging heat treatment regulation process step after the forming of the aluminum alloy, improve the production efficiency, and avoid the deformation of heat treatment; II. The rubber bag shaping of the aluminum alloy complex thin-walled part at high temperature can greatly reduce the deformation resistance in the deformation process and promote the aging treatment of the aluminum alloy under high stress, which is beneficial to the shape-property synergistic regulation of the aluminum alloy complex thin-walled part; III. The innovative rubber bag heat shaping of the aluminum alloy in the aging state improves the forming efficiency, reduces the rubber bag shaping time, and improves the workpiece shaping size; IV. The combination of the rubber bag hydraulic heat shaping and the progressive rolling, deep drawing and other sheet metal forming can complete the pre-forming by sheet metal forming, the subsequent local accurate shaping and the elimination of surface defects by the rubber bag hydraulic heat shaping of the size distorted aluminum alloy complex thin-walled part, and the aging strengthening treatment of the aluminum alloy at the same time. The process can improve the forming efficiency, improve the material utilization rate, and reduce the manufacturing cost by using sheet metal forming to manufacture the aluminum alloy thin-walled part blank. The size precision is improved, the surface defects are eliminated, and the subsequent aging strengthening of the aluminum alloy is completed by using the rubber bag hydraulic heat forming for post-treatment shaping. BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 The process flow chart for preparing the aluminum alloy thin-walled part by the rubber bag heat shaping; Figure 2 The process and equipment schematic diagram for preparing the aluminum alloy thin-walled part by the rubber bag heat shaping; Among them, 1 is heat-resistant hydraulic oil, 2 is rubber bag, 3 is rigid mold, 4 is rubber bag upper die, 5 is aluminum alloy thin-walled part blank, 6 is positioning pin, 7 is clamping positioning block, and 8 is rubber bag lower die. DETAILED DESCRIPTION

[0015] In order to make the purpose, technical scheme and effect of the present application more clear and definite, the following examples are used to further illustrate the present application. It should be pointed out that the specific implementation described here is only used to explain the present application, and is not used to limit the present application.

[0016] As Figure 1 shown, the specific steps of a method for preparing an aluminum alloy thin-walled part by using sheet metal forming and then rubber bag hot shaping according to the present application are as follows: Step one, use sheet metal forming methods such as progressive roll forming and deep drawing to form the whole aluminum alloy thin-walled part, and obtain the aluminum alloy thin-walled part blank 5; Step two, solid solution treatment of the aluminum alloy thin-walled part blank 5 after sheet metal forming, solid solution treatment temperature 470-550℃, holding time 30-90min, water quenching; Step three, store the solid-solution-treated aluminum alloy thin-walled part blank 5 in a refrigerator for standby; Step four, install the rigid mold 3 and rubber bag 2 on the press, and use high-temperature furnace, hot oil or heating rod to heat the rigid mold 3, rubber bag 2, and heat-resistant hydraulic oil 1 in the rubber bag to 160-220℃, and keep the temperature stable; Step five, raise the press, open the rigid mold 3, and quickly place the aluminum alloy thin-walled part blank 5 in the new quenched state on the hot rigid mold 3, and use the positioning pins 6 and clamping positioning blocks 7 to complete the positioning of the rigid mold 3 and the aluminum alloy thin-walled part blank 5; Step six, quickly close the mold, inject heat-resistant hydraulic oil 1 into the rubber bag through the oil pump, and simultaneously increase the pressure of the press, so that the rubber bag and the hydraulic press are simultaneously pressurized to the respective set pressures; Step seven, the rubber bag expands and extrudes the aluminum alloy thin-walled part blank 5, forcing the aluminum alloy thin-walled part blank 5 to tightly adhere to the rigid mold 3, and transferring the temperature of the mold to the aluminum alloy thin-walled part blank 5, at this time the holding pressure is 5-200MPa; Step eight, under the combined action of the high pressure and heat field of the rubber bag 2, the aluminum alloy thin-walled part blank 5 undergoes aging strengthening and stress relaxation, reduces springback, and simultaneously improves strength and forming precision, and the aging heat treatment time is 1-24h; Step nine, simultaneously unload the pressure of the rubber bag and the hydraulic press, raise the rubber bag upper die 4 to make it away from the rubber bag lower die 8, and the rubber bag returns to the initial position; Step ten, open the press, take out the aluminum alloy thin-walled part blank 5, and place it in a cooling tool for uniform cooling, to obtain the aluminum alloy thin-walled part finished product. Embodiment

[0017] This embodiment is directed to the rubber bag hot shaping of a 2219 aluminum alloy intake port lip part, with a wall thickness of 2-5mm and a diameter size of more than one meter, and now specific examples are listed for illustration, and the device schematic diagram is as Figure 2 . The processing is carried out according to the following steps: Step one, use sheet metal forming methods such as progressive roll forming to form the whole aluminum alloy thin-walled part, and obtain the lip part blank 5; Step two, the lip piece blank 5 after progressive roll forming is solid solution treated, the solid solution treatment is kept at 535~545℃ for about 60min, and water quenching is used for quenching; Step three, the solid solution treated lip piece blank 5 is placed in a refrigerator for standby; Step four, the rigid mold 3 and the rubber bag 2 are installed on the press, and the rigid mold 3, the rubber bag 2, the heat-resistant hydraulic oil 1 in the rubber bag, etc. are heated to 175~185℃ by using a high-temperature furnace, hot oil or a heating rod, etc. as a heating method, and the temperature is kept stable; Step five, the press is raised, the rigid mold 3 is opened, the lip piece blank 5 in the new quenched state after solid solution treatment is quickly placed above the hot rigid mold 3, and the positioning pin 6 and the clamping positioning block 7 are used to complete the positioning of the rigid mold 3 and the lip piece blank 5; Step six, the mold is quickly closed, the heat-resistant hydraulic oil 1 is pumped into the rubber 2 through the oil pump, and the pressure of the press is simultaneously increased, so that the rubber bag 2 and the hydraulic machine are simultaneously pressurized to the respective set pressures; Step seven, the rubber bag 2 expands and extrudes the lip piece blank 5, forcing the lip piece blank 5 to tightly adhere to the rigid mold 3, and the temperature of the mold 3 is transferred to the lip piece blank 5, at this time the holding pressure is 15MPa; Step eight, the lip piece blank 5 is subjected to aging strengthening and stress relaxation under the combined action of the high pressure and the hot field of the rubber bag 2, the springback is reduced, the strength and the forming precision are simultaneously improved, and the aging heat treatment time is 22h; Step nine, the rubber bag and the hydraulic machine pressure are simultaneously unloaded, the rubber bag upper die 4 is raised to move away from the rubber bag lower die 8, and the rubber bag 2 returns to the initial position; Step ten, the press is opened, the lip piece 5 is taken out and placed in a cooling tool for uniform cooling, and the 2219 aluminum alloy intake port lip thin-walled part finished product is obtained. Embodiment

[0018] This embodiment is aimed at the rubber bag hot correction of the 2024 aluminum alloy skin part, the wall thickness is 1~3mm, the size is about one meter or so, and now specific examples are listed for description, and the device schematic diagram is as shown in Figure 2 The following steps are used for processing: Step one, the 2024 aluminum alloy skin part is integrally formed by using a deep drawing forming method, and a 2024 aluminum alloy skin part blank 5 is obtained; Step two, the skin part blank 5 after stamping forming is solid solution treated, the solid solution treatment temperature is 495~505℃, the holding time is 60min, and water quenching is used for quenching; Step three, the solid solution treated skin part blank 5 is placed in a refrigerator for standby; Step four, install rigid mold 3, rubber bag 2, etc. on the press, heat the rigid mold 3, rubber bag 2, heat-resistant hydraulic oil 1 in the rubber bag, etc. as a whole to the aging temperature of 165~175℃ by high temperature furnace or hot oil heating or heating rod, etc. and keep the temperature stable; Step five, raise the press, open the rigid mold 3, quickly place the skin part blank 5 in the new quenching state after solid solution on the hot rigid mold 3, and complete the positioning of the rigid mold 3 and the skin part blank 5 by using the positioning pin 6 and the clamping positioning block 7; Step six, quickly close the mold, inject heat-resistant hydraulic oil 1 into the rubber bag through the oil pump, and simultaneously increase the pressure of the press, so that the rubber bag 2 and the hydraulic press are simultaneously pressurized to the respective set pressure; Step seven, the rubber bag 2 expands and extrudes the skin part blank 5, forcing the skin part blank 5 to tightly adhere to the rigid mold 3, and the temperature of the mold 3 is transferred to the aluminum alloy skin part 5, at this time the holding pressure is 20MPa; Step eight, under the combined action of high pressure and hot field of the rubber bag 2, the skin part blank 5 occurs aging strengthening and stress relaxation, reduces springback, synchronously improves strength and forming precision, and the aging heat treatment time is 8h; Step nine, simultaneously unload the rubber bag and the hydraulic press pressure, raise the rubber bag upper die 4 to make it away from the rubber bag lower die 8, and the rubber bag 2 returns to the initial position; Step ten, open the press, take out the skin part 5, and place it in the cooling tool for uniform cooling to obtain the finished product of 2024 aluminum alloy skin thin-walled part. Embodiment

[0019] This embodiment is aimed at the rubber bag hot correction of 7075 aluminum alloy bulkhead part, the part is slender, the wall thickness is 3~5mm, the length is about half a meter, and the width is about 50mm. Now specific examples are listed for description, and the equipment schematic diagram is as follows Figure 2 The following steps are carried out: Step one, use hot stamping method to form 7075 aluminum alloy bulkhead part as a whole to obtain 7075 aluminum alloy bulkhead part blank 5; Step two, solid solution treatment is carried out on the bulkhead part blank 5 after hot stamping, the solid solution treatment temperature is 490~510℃, the holding time is about 60min, and water cooling quenching is carried out; Step three, place the bulkhead part blank 5 after solid solution into the refrigerator for storage; Step four, install rigid mold 3, rubber bag 2, etc. on the press, heat the rigid mold 3, rubber bag 2, heat-resistant hydraulic oil 1 in the rubber bag, etc. as a whole to the aging temperature of 200℃ by high temperature furnace or hot oil heating or heating rod, etc. and keep the temperature stable; Step five, lift the press, open the rigid mold 3, quickly place the frame blank 5 in the solution in the new quenching state on the hot rigid mold 3, and use the positioning pin 6 and the clamping positioning block 7 to complete the positioning of the rigid mold 3 and the frame blank 5; Step six, quickly close the mold, inject heat-resistant hydraulic oil 1 into the rubber bag through the oil pump, and simultaneously increase the pressure of the press, so that the rubber bag 2 and the hydraulic machine are simultaneously pressurized to the respective set pressures; Step seven, the rubber bag 2 expands and extrudes the frame blank 5, forcing the frame blank 5 to adhere to the rigid mold 3, and the temperature of the mold 3 is transferred to the frame blank 5, at this time the pressure is 150 MPa; Step eight, under the combined action of the high pressure of the rubber bag 2 and the heat field, the frame blank 5 occurs aging strengthening and stress relaxation, reduces the springback, synchronously improves the strength and forming precision, and the aging heat treatment time is 1 h; Step nine, simultaneously unload the rubber bag 2 and the hydraulic machine pressure, lift the rubber bag upper die 4, make it away from the rubber bag lower die 8, and the rubber bag returns to the initial position; Step ten, open the press, take out the frame 5, place it in the cooling tool, and uniformly cool to obtain the finished product of the 7075 aluminum alloy frame thin-walled part.

[0020] The present application has many specific implementation ways, and the above description is only the preferred embodiment of the present application. It should be pointed out that for ordinary skilled persons in the technical field, some improvements can be made without departing from the principles of the present application, and these improvements should also be considered as the protection scope of the present application.

Claims

1. A method for manufacturing an aluminum alloy thin-walled part by using a rubber bag hot forming after sheet metal forming, characterized in that, The method is: Step one, using progressive rolling, deep drawing sheet metal forming method for aluminum alloy thin-walled parts overall forming, obtain aluminum alloy thin-walled parts blank; Step two, the sheet metal forming after aluminum alloy thin-walled parts blank solid solution treatment; Step three, the solid solution after the new quenching state aluminum alloy thin-walled parts blank put into the freezer for standby; Step four, the rigid die and rubber bag are installed on the press, the rigid die, rubber bag, rubber bag heat resistant hydraulic oil is heated to the aluminum alloy heat correction and aging temperature, keep temperature stable; Step five, lift the press, open the rigid die, the new quenching state aluminum alloy thin-walled parts blank is placed in the hot rigid die, using positioning pin and clamping positioning block complete rigid die and aluminum alloy thin-walled parts positioning; Step six, fast die, through the oil pump into the heat resistant hydraulic oil in the rubber bag, synchronous increase the pressure of the press, make the rubber bag and hydraulic machine synchronous pressurization to the respective set pressure; Step seven, the rubber bag expands extrusion aluminum alloy thin-walled parts, force aluminum alloy thin-walled parts to adhere to the rigid die, in the deformation, aluminum alloy thin-walled parts is heated to aging temperature, and long time pressure keeping; Step eight, aluminum alloy thin-walled parts blank under the action of high pressure and high temperature of rubber bag, deformation, adhere to the die, occur aging strengthening and stress relaxation, synchronous improve the strength and forming precision; Step nine, synchronous unload the rubber bag and hydraulic machine pressure to zero, lift the press, the rubber bag back to the initial position; Step ten, take out the aluminum alloy thin-walled parts, placed in the cooling tool uniform cooling to room temperature, get qualified aluminum alloy thin-walled parts.

2. The method for manufacturing an aluminum alloy thin-walled part by using sheet metal forming and post-forming rubber bag hot calibration according to claim 1, characterized in that, In step two, the solid solution treatment temperature is 470-550 DEG C, according to the thickness and structure of aluminum alloy thin-walled parts blank, the holding time is about 30-90 min, the part is immediately quenched in water after taking out.

3. The method for manufacturing an aluminum alloy thin-walled part by using sheet metal forming and post-forming rubber bag hot calibration according to claim 1, characterized in that, In step four, the rigid die, rubber bag and heat resistant hydraulic oil are heated and kept for a period of time, and kept in the aging temperature range of aluminum alloy, so that the aluminum alloy part can be aged simultaneously during heat correction.

4. The method for manufacturing an aluminum alloy thin-walled part by using sheet metal forming and post-forming rubber bag hot calibration according to claim 1, characterized in that, The aging temperature of the aluminum alloy is 160-220 DEG C.

5. The method for manufacturing an aluminum alloy thin-walled part by using sheet metal forming and post-forming rubber bag hot calibration according to claim 1, characterized in that, In step six, the internal oil pressure of the rubber bag is 5-200 MPa, and the pressure keeping time is 1-24 h.

6. The method for manufacturing an aluminum alloy thin-walled part by using sheet metal forming and post-forming rubber bag hot calibration according to claim 1, characterized in that, In step seven, the elastic modulus of the rubber bag is 1.2-1.4 GPa, and the poisson's ratio is 0.48-0.

5.

7. The method for manufacturing an aluminum alloy thin-walled part by rubber bag hot forming after sheet metal forming according to claim 1, characterized in that, The rigid die is fixed on the rubber bag lower die (8), and the positioning pin (6) is used to complete the positioning of the convex die and the rubber bag lower die (8), and the clamping positioning block (7) is used to complete the positioning and sealing of the convex die and the rubber bag upper die (4); the solid solution treated aluminum alloy thin-walled parts blank is placed above the rigid die (3), the rubber bag (2) is used as the concave die, and finally the rubber bag upper die (4) and the rubber bag lower die (8) are closed.

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