Multi-station hot forming and quenching process for aluminum sheets

Abstract

This invention discloses a multi-station hot forming and quenching process for aluminum plates. After solution treatment, the billet is hot-pressed, with changes in pressure and temperature. The temperature changes integrate quenching and cryogenic treatment to improve product performance and microstructure. A second cryogenic treatment followed by short-term aging eliminates stress and further enhances product performance. The resulting product exhibits significantly increased strength, stable dimensions, and no springback, making it particularly suitable for forming parts with negative angles. The process integrates hot forming, punching, and shaping processes, saving turnaround time between subsequent processes, improving production efficiency, and helping to reduce costs.

Description

Technical Field

[0001] This invention relates to the field of aluminum plate forming technology, specifically to the multi-station hot forming and quenching process of aluminum plates. Background Technology

[0002] Aluminum alloys have advantages such as low density, high strength, good plasticity, and the ability to be processed into various profiles, and are widely used in aerospace, aviation, automobile manufacturing and other industries. For example, the common 7-series aluminum alloys have excellent performance, but are difficult to form. With the rapid development of aluminum alloy hot forming technology, 7-series aluminum alloys can be processed into relatively complex parts, such as side beams and window lintels, through hot forming.

[0003] However, with the increase in demand, the performance of 7-series aluminum alloys in terms of strength and other aspects cannot meet the requirements. Most of the improvements on the market are focused on the casting composition, or on the improvement of later aging and solution treatment. Relatively speaking, the improvement of the performance of 7-series aluminum alloys in terms of strength and other aspects is relatively small and needs to be improved. Summary of the Invention

[0004] To address at least one of the aforementioned technical deficiencies, the present invention provides the following technical solution:

[0005] This application discloses a multi-station hot forming and quenching process for aluminum plates, including the following steps:

[0006] First, heat-treat the aluminum sheet blank to bring it into a solution-free state;

[0007] Second, the aluminum sheet blank in the solution-solid state is placed in multiple hot forming molds for hot pressing, and the blank is kept in the solution-solid state during the process.

[0008] Third, the intermediate product formed by hot pressing of the aluminum sheet blank is left to stand and the temperature and pressure of the space are adjusted for processing, including the first, second, third, fourth and fifth stages. The first stage: maintain the temperature at 525-550℃ and the pressure at 85-95MPa for 0.5-1h; the second stage: reduce the temperature to 140-160℃ and the pressure to 60-70MPa; the third stage: maintain the temperature at 140-160℃ and the pressure at 60-70MPa for 3-6h; the fourth stage: cool down to -160-180℃ and maintain at -160-180℃ for 2-4h, reduce the pressure to atmospheric pressure and maintain it; the fifth stage: heat up to room temperature.

[0009] Fourth, trim the outline of the intermediate product;

[0010] Fifth, adjust the temperature of the space where the product is located after repair, including cooling it down to -175-190℃ and maintaining it for 1-2 hours, then raising it to 160-180℃ and maintaining it for 2-4 hours, and then restoring it to normal temperature.

[0011] This method involves hot pressing the billet after solution treatment, and changing the pressure and temperature. The temperature change integrates quenching and cryogenic treatment to promote product performance and improve the microstructure. After finishing, a second cryogenic treatment is carried out in conjunction with short-time aging treatment to eliminate stress and further improve product performance. The formed product has the advantages of significantly improved strength, stable product dimensions and no springback, and is especially suitable for forming parts with negative angle shapes.

[0012] Furthermore, the contour trimming of intermediate products is carried out using progressive dies. The trimming range includes trimming, punching, or flanging. The trimming process can be increased or decreased according to actual needs. Progressive die operation does not require large-scale workpiece transfer, which helps to save time and improve efficiency.

[0013] Furthermore, the composition of this aluminum plate blank is as follows: Zn 5.3-5.6%, Cu 1.1-1.3%, Mg 2.0-2.2%, Mn 0.08-0.11%, Ti 0.05-0.1%, Cr 0.18-0.22%, Fe 0.4-0.5%, SiC 0.08-0.11%, Al balance. This design improves the aluminum plate alloy composition by increasing the SiC content to enhance the product's mechanical properties.

[0014] Furthermore, the SiC in the composition is a mixture of whisker and granular states in a ratio of 1:2, which improves the mechanical properties of the product.

[0015] Furthermore, the solution treatment temperature of the aluminum sheet blank is 530-550℃.

[0016] Furthermore, each hot pressing is performed to form 20-60% of the target part shape.

[0017] Furthermore, the blank is prepared before heat treatment, and the blank is cut or punched through a mold to obtain the required blank shape.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0019] 1. This invention improves the aluminum plate forming process by hot pressing after solution treatment, adjusting the pressure and temperature, and then performing a second deep cryogenic treatment and aging treatment after finishing. This process helps to improve the product's microstructure and mechanical properties such as strength, solves the problem of springback in parts, and helps to improve dimensional stability.

[0020] 2. This invention integrates thermoforming, punching and shaping processes into one, saving turnaround time between subsequent processes, improving production efficiency, and helping to reduce costs. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying 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.

[0022] Figure 1 This is a flowchart of the multi-station thermoforming and quenching process for this aluminum plate. Detailed Implementation

[0023] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0024] For the composition of aluminum sheet blanks, the selectable composition range is as follows: Zn 5.3-5.6%, Cu 1.1-1.3%, Mg 2.0-2.2%, Mn 0.08-0.11%, Ti 0.05-0.1%, Cr 0.18-0.22%, Fe 0.4-0.5%, SiC 0.08-0.11%, Al balance.

[0025] Options include: Zn 5.3%, Cu 1.1%, Mg 2.0%, Mn 0.08%, Ti 0.05%, Cr 0.2%, Fe 0.45%, SiC 0.11%, and Al balance.

[0026] Options include: Zn 5.6%, Cu 1.3%, Mg 2.2%, Mn 0.11%, Ti 0.06%, Cr 0.21%, Fe 0.5%, SiC 0.10%, and Al balance.

[0027] Options include: Zn 5.4%, Cu 1.2%, Mg 2.1%, Mn 0.10%, Ti 0.05%, Cr 0.22%, Fe 0.48%, SiC 0.09%, and Al balance.

[0028] Of course, other component ratios can also be used.

[0029] For SiC, either whisker or granular states can be selected. In this scheme, a mixture of whisker and granular states is preferred. The mixing ratio is, for example, 1:1, 1:2, 1:3, 2:1, 3:1, etc., with a 1:2 ratio being the most preferred.

[0030] For the forming of aluminum sheet blanks, conventional process flow and parameters can be used, and there are no restrictions.

[0031] Regarding the solution treatment temperature of this aluminum slab blank, the aluminum slab blank in this scheme is based on 7-series aluminum alloy with added SiC component. The solution treatment temperature can be referenced from that of 7-series aluminum alloy, such as 530-550℃, specifically 540±5℃, 545±5℃, etc. For equipment, refer to common equipment.

[0032] Similarly, for cryogenic treatment, please refer to the commonly used equipment; there will be no further details here.

[0033] This includes thermoforming molds and matching stamping equipment, as well as stamping equipment and molds for contour trimming, and aging treatment equipment, etc. (See Common Equipment for details).

[0034] The following is a specific example: the blank is prepared before heat treatment, and the blank is cut or cut with a mold to obtain the required blank shape.

[0035] Example 1

[0036] The multi-station hot forming and quenching process for aluminum sheets includes the following steps:

[0037] First, heat-treat the aluminum billet to bring it into a solution state at a solution temperature of 535℃. The composition of the aluminum billet is: Zn 5.4%, Cu 1.1%, Mg 2.1%, Mn 0.11%, Ti 0.05%, Cr 0.2%, Fe 0.45%, SiC 0.11%, and Al balance. Among them, SiC is a mixture of whisker and granular states, with a whisker to granular state ratio of 1:2, according to the mass ratio.

[0038] Second, the aluminum sheet blank in the solution-solid state is placed sequentially into multiple thermoforming dies for hot pressing, during which the blank is kept in a solution-solid state, such as... Figure 1 As shown, hot pressing is performed to complete the target shape in three stages, completing 30%, 30%, and 40% of the target shape in sequence. The hot pressing parameters can be referenced from the standard.

[0039] Third, the intermediate product formed by hot pressing of aluminum sheet blank is placed in a closed space and the temperature and pressure of the space are adjusted for processing.

[0040] The first stage involves placing the intermediate product in a sealed space, heating the sealed space to 540±5℃ and 90±2MPa, maintaining this temperature and pressure for 0.6h, with a heating rate of 0.3K / s.

[0041] Second stage: Reduce the temperature to 150±3℃, the cooling rate is 0.3K / s, and reduce the pressure to 65±2MPa;

[0042] Third stage: Maintain temperature at 150±3℃, pressure at 65±2MPa, and time at 3.5h;

[0043] Fourth stage: Cool down to -170±3℃, reduce pressure to atmospheric pressure, maintain for 3 hours, cooling rate is 0.3 K / s;

[0044] Fifth stage: Heat to room temperature at a rate of 0.3 K / s;

[0045] Fourth, the intermediate product is contoured using a progressive die. The trimming process includes trimming, punching, and flanging.

[0046] Fifth, after repair, place the product in a sealed space and adjust the temperature of the space to -180±3℃ and maintain it for 1.5 hours. Then raise the temperature to 170±5℃ and maintain it for 2.5 hours. After that, return it to room temperature. The heating and cooling rate is 0.3 K / s.

[0047] Example 2

[0048] The multi-station hot forming and quenching process for aluminum sheets includes the following steps:

[0049] First, heat-treat the aluminum billet to bring it into a solution state at a solution temperature of 540℃. The composition of the aluminum billet is: Zn 5.3%, Cu 1.1%, Mg 2.0%, Mn 0.08%, Ti 0.05%, Cr 0.21%, Fe 0.5%, SiC 0.11%, and Al balance. Among them, SiC is a mixture of whisker and granular states, with a whisker to granular state ratio of 1:2, according to the mass ratio.

[0050] Second, the aluminum sheet blank in the solution-solid state is placed sequentially into multiple thermoforming dies for hot pressing, during which the blank is kept in a solution-solid state, such as... Figure 1 As shown, hot pressing is performed to complete the target shape in three stages, completing 30%, 40%, and 30% of the target shape in sequence. The hot pressing parameters can be referenced from the standard.

[0051] Third, the intermediate product formed by hot pressing of aluminum sheet blank is placed in a closed space and the temperature and pressure of the space are adjusted for processing.

[0052] The first stage involves placing the intermediate product in a sealed space, heating the sealed space to 530±5℃ and 90±5MPa, maintaining this temperature and pressure for 0.8h, with a heating rate of 0.2K / s.

[0053] Second stage: Reduce the temperature to 155±3℃, the cooling rate is 0.2K / s, and reduce the pressure to 68±2MPa;

[0054] Third stage: Maintain temperature at 155±3℃, pressure at 68±2MPa, for 4 hours;

[0055] Fourth stage: Cool down to -175±3℃, reduce pressure to atmospheric pressure, maintain for 3 hours, cooling rate is 0.2 K / s;

[0056] Fifth stage: Heat to room temperature at a rate of 0.2 K / s;

[0057] Fourth, the intermediate product is contoured using a progressive die. The trimming process includes trimming, punching, and flanging.

[0058] Fifth, after repair, place the product in a sealed space and adjust the temperature of the space to -185±3℃ and maintain it for 2 hours. Then raise the temperature to 175±5℃ and maintain it for 2 hours. After that, restore it to room temperature. The heating and cooling rate is 0.2 K / s.

[0059] Example 3

[0060] The multi-station hot forming and quenching process for aluminum sheets includes the following steps:

[0061] First, heat-treat the aluminum billet to bring it into a solution state at a solution temperature of 545℃. The composition of the aluminum billet is: Zn 5.6%, Cu 1.3%, Mg 2.2%, Mn 0.11%, Ti 0.06%, Cr 0.21%, Fe 0.5%, SiC 0.10%, and Al balance. Among them, SiC is a mixture of whisker and granular states, with a whisker to granular state ratio of 1:2, according to the mass ratio.

[0062] Second, the aluminum sheet blank in the solution-solid state is placed sequentially into multiple thermoforming dies for hot pressing, during which the blank is kept in a solution-solid state, such as... Figure 1 As shown, hot pressing is performed to complete the target shape in three stages, completing 40%, 30%, and 30% of the target shape in sequence. The hot pressing parameters can be referenced from the standard.

[0063] Third, the intermediate product formed by hot pressing of aluminum sheet blank is placed in a closed space and the temperature and pressure of the space are adjusted for processing.

[0064] The first stage involves placing the intermediate product in a sealed space, heating the sealed space to 540±5℃ and 90±2MPa, maintaining this temperature and pressure for 0.6h, with a heating rate of 0.3K / s.

[0065] Second stage: Reduce the temperature to 155±2℃, the cooling rate is 0.3K / s, and reduce the pressure to 67±1MPa;

[0066] Third stage: Maintain temperature at 155±2℃, pressure at 67±1MPa, for 5 hours;

[0067] Fourth stage: Cool down to -175±1℃, reduce pressure to atmospheric pressure, maintain for 2 hours, cooling rate is 0.2 K / s;

[0068] Fifth stage: Heat to room temperature at a rate of 0.3 K / s;

[0069] Fourth, the intermediate product is contoured using a progressive die. The trimming process includes trimming, punching, and flanging.

[0070] Fifth, after repair, place the product in a sealed space and adjust the temperature of the space to -185±1℃ and maintain it for 1 hour. Then raise the temperature to 170±5℃ and maintain it for 4 hours. After that, return it to room temperature. The heating and cooling rate is 0.2 K / s.

[0071] Comparative Example 1

[0072] Compared with Example 1, in this example, the aluminum plate multi-station hot forming and quenching process has the following characteristics: the aluminum plate blank does not contain SiC components, but the other components are the same.

[0073] Comparative Example 2

[0074] The multi-station hot forming and quenching process for aluminum sheets includes the following steps:

[0075] First, heat-treat the aluminum billet to bring it into a solution state at a solution temperature of 535℃. The composition of the aluminum billet is: Zn 5.4%, Cu 1.1%, Mg 2.1%, Mn 0.11%, Ti 0.05%, Cr 0.2%, Fe 0.45%, SiC 0.11%, and Al balance. Among them, SiC is a mixture of whisker and granular states, with a whisker to granular state ratio of 1:2, according to the mass ratio.

[0076] Second, the aluminum sheet blank in the solution-solid state is placed sequentially into multiple thermoforming dies for hot pressing, during which the blank is kept in a solution-solid state, such as... Figure 1 As shown, hot pressing is performed to complete the target shape in three stages, completing 30%, 30%, and 40% of the target shape in sequence. The hot pressing parameters can be referenced from the standard.

[0077] Third, water quenching treatment can be performed according to standard procedures.

[0078] Fourth, the intermediate product is contoured using a progressive die. The trimming process includes trimming, punching, and flanging.

[0079] Fifth, after repair, place the product in a sealed space and adjust the temperature of the space to -180±3℃ and maintain it for 1.5 hours. Then raise the temperature to 170±5℃ and maintain it for 2.5 hours. After that, return it to room temperature. The heating and cooling rate is 0.3 K / s.

[0080] The performance of the products prepared above was tested, as shown in the table below:

[0081]

[0082] As can be seen from the table above, the aluminum alloy products under the scheme exhibit excellent performance in yield strength and tensile strength.

[0083] The reason for this is that, in terms of the microstructure of the above products, compared with the comparative example, the eutectic structure around the micropores in the product of the embodiment has basically disappeared, the average size of the micropores has been greatly reduced, the phenomenon of dendrite segregation has been significantly alleviated, and the homogenization of the composition has been improved.

[0084] The above are merely preferred embodiments of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principle of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. Process for the multistation hot forming and quenching of aluminium sheets, characterised in that, The method comprises the following steps: First, heat the aluminum plate blank to a solid solution state; Second, heat press the aluminum plate blank in a solid solution state in a plurality of hot forming dies, keeping the blank in a solid solution state during the process; Third, keep the aluminum plate blank heat press formed intermediate product static and adjust the temperature and pressure of the space where the product is located for processing, including first, second, third, fourth and fifth stages, wherein the first stage: keep the temperature at 525-550℃, the pressure at 85-95MPa, and the time at 0.5-1h, the second stage: reduce the temperature to 140-160℃ and the pressure to 60-70MPa, the third stage: keep the temperature at 140-160℃, the pressure at 60-70MPa, and the time at 3-6h, the fourth stage: reduce the temperature to -160-180℃ and keep it at -160-180℃ for 2-4h, reduce the pressure to normal pressure and keep it, and the fifth stage: increase the temperature to normal temperature; Fourth, profile the intermediate product; Fifth, adjust the temperature of the space where the product is located, wherein the temperature is reduced to -175-190℃ and kept for 1-2h, then increased to 160-180℃ and kept for 2-4h, and finally returned to normal temperature.

2. The multi-station thermal forming and quenching process for aluminum plate as claimed in claim 1, wherein: In the fourth step, the profile of the intermediate product is processed by a continuous die, and the trimming range includes trimming, punching or flanging.

3. The multi-station thermal forming and quenching process for aluminum plate as claimed in claim 1, wherein: The aluminum plate blank comprises the following components: Zn 5.3-5.6%, Cu 1.1-1.3%, Mg 2.0-2.2%, Mn 0.08-0.11%, Ti 0.05-0.1%, Cr 0.18-0.22%, Fe 0.4-0.5%, SiC 0.08-0.11%, and Al the balance.

4. The multi-station thermal forming and quenching process for aluminum plate as claimed in claim 3, wherein: The SiC in the components is a mixture of whisker and particle states, and the ratio of the two is 1:

2.

5. The multi-station thermal forming and quenching process for aluminum plate as claimed in claim 1 wherein: The solid solution temperature of the aluminum plate blank is 530-550℃.

6. The multi-station thermal forming and quenching process for aluminum plate as claimed in claim 1 wherein: Each heat press forming is 20-60% of the shape of the target part.

7. The multi-station thermal forming and quenching process for aluminum plate as claimed in claim 1 wherein: Before heating treatment, the blank is arranged, and the required blank shape is obtained by die blanking or cutting.

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