JP7614389B2 - Aluminum alloy plate processing method - Google Patents

Description

The present invention relates to a method for processing aluminum alloy sheets.

Aluminum (aluminum alloy) sheet material is effective as a lightweight alternative to steel plate products, and is used, for example, in automobile parts. Pressed product applications of aluminum sheet material include exterior panel products such as hoods, trunks, fenders, and doors. In addition, applications of aluminum sheet material for internal vehicle products include heat exchanger parts (radiators, etc.) around the engine for heat dissipation, and heat insulators. Aluminum sheet material is not widely used for internal product applications other than these. Aluminum sheet material is significantly inferior in formability to steel plate and also lacks strength, so it is required that the plate thickness be made considerably thicker.

Aluminum alloy products include engine parts (aluminum castings) and cases for control and function integration (aluminum die-cast products). These are formed by pouring molten aluminum into a mold, and are good at complex shapes and one-piece molding. The aluminum alloy used is 4000 series Al-Si material, which has different material properties than the wrought materials used in processing (1000 series, 2000 series, 3000 series, 5000 series, 6000 series, 7000 series). The fluidity of the molten metal is important for aluminum alloys for casting, and they are characterized by their high Si content. AC4A is a typical example of a casting alloy, and ADC12 is a die-cast alloy. Casting technology is excellent for mass production of both large and small items. However, for example, die-cast products (ADC12) have issues due to being cast products (defects inside the material: shrinkage cavities, etc., dimensional accuracy: cutting required), as well as issues such as deterioration of corrosion resistance due to the addition of Cu to the aluminum alloy.

On the other hand, the automobile industry is promoting the weight reduction of the entire vehicle by using multi-materials from the viewpoint of electric vehicles (PHEVs (Plug-in Hybrid Electric Vehicles), EVs (Electric Vehicles), etc.), autonomous driving (equipped with various sensors), and ensuring safety. Furthermore, in recent years, the promotion of carbon neutrality has been required, and the nature of the material itself is also important. In other words, it is important whether the material is virgin ingot, which consumes a large amount of electricity for its production, or recycled products, which do not consume a large amount of electricity, are used. In addition to conventional pressing (cold) technology, the adoption of hot stamping technology has become prominent for steel plates, which account for the majority of the vehicle body weight. Hot stamping technology is being applied especially to cabin structural parts (ultra-high tensile steel plates) for passenger protection. However, although prototypes of hot stamping technology for aluminum alloy plates are recognized at exhibitions, none of them are expected to be put into practical use.

JP 2009-241140 A JP 2018-073985 A Patent No. 5681631 Japanese Patent Application Publication No. 9-78210 JP 2003-277837 A Japanese Patent Application Publication No. 8-67953

In recent years, the world situation has led to a desire to go carbon-free in order to prevent global warming. Many automotive parts require a lot of energy at the raw material, material and processing stages. CO2 emissions vary depending on the type of power generation (thermal, hydroelectric, nuclear, solar, wind, etc.), but in the future (after 2050), it is desirable to use renewable energy, and a shift away from fossil fuels will be important to go carbon-free. However, for the time being, it is necessary to promote recycling and reuse, which are effective in reducing CO2 emissions caused by raw materials, as well as reducing the amount of fossil fuels used in manufacturing processes and shortening processing and heat treatment times in parts manufacturing.

Aluminum materials used in Japan are made from imported new aluminum ore (99.7% Al) in large quantities, and are produced to match customer needs (ingredients, strength, etc.). Among these, beverage can material and die-casting material ADC12 are products that are successfully recycled. Materials for other uses are also recycled without waste, but as the proportion of new ore used is high, further improvement activities are required to reduce CO2 emissions.

In light of the recent trend towards carbon neutrality (targeted for 2050) and the use of aluminum as a material, new aluminum ingots require a huge amount of energy to be produced, resulting in the emission of large amounts of CO2. For this reason, it is desirable to refrain from using new aluminum ingots. Promoting the recycling and reuse of aluminum products is extremely important. Reusing aluminum products requires only about 3% of the energy required to produce new ingots, so it is effective not only for energy conservation but also for LCA (Life-Cycle Assessment) and future carbon neutrality.

In this situation, the electrification of automobiles (especially EVs (Electric Vehicles) and FCVs (Fuel Cell Vehicles)) is expected to expand rapidly after 2030. On the other hand, the number of engine-equipped vehicles is expected to decrease dramatically. Many engine parts for engine-equipped vehicles are made of aluminum castings, and the destination (use and processing method) of aluminum castings (aluminum alloy castings) from scrapped engine-equipped vehicles is a future issue. In particular, aluminum castings are mainly 4000 series aluminum alloys with a high Si content (e.g., 5% or more by weight), and it is difficult to convert them to wrought materials (1000 series, 2000 series, 3000 series, 5000 series, 6000 series, 7000 series aluminum alloys). If the two types of wrought materials are the same, they can easily be returned to the same type of wrought material (composition adjustment: scrap and a small amount of new ingot). When turning cast materials back into wrought materials, a method is considered in which the silicon content is diluted with a large amount of virgin ingot and wrought material scrap, but this has little effect on reducing CO2 emissions. It would be desirable to be able to use aluminum castings as wrought materials without using a large amount of virgin ingot.

The present invention aims to provide a hot stamping technology for aluminum alloy sheet material containing Si.

In order to solve the above problems, the following measures are adopted.
That is, the first aspect is
A heating step of holding an aluminum alloy plate made from an aluminum alloy containing 5% or more and less than 11% Si by weight at a temperature of 450° C. or more and less than 560° C. for 10 minutes or less;
and a press working step of supplying the aluminum alloy plate to a die and pressing the aluminum alloy plate, and cooling the aluminum alloy plate to 200° C. or less at a bottom dead center of the press working,
The thickness of the aluminum alloy plate is 0.8 mm or more and less than 5 mm.
A method for processing an aluminum alloy plate.

According to the present invention, a hot stamping technology for aluminum alloy sheet material containing Si can be provided.

FIG. 1 is a diagram showing an example of the configuration of a die of a press working device. FIG. 2 is a diagram showing an example of a cooling water channel 150 and a thermocouple installation hole 160 provided in the lower die set 122 of the mold 100. FIG. 3 is a diagram showing an example of the configuration of a die of a press working device. FIG. 4 is a diagram showing an example of an operation flow of a hot stamping method for an aluminum alloy sheet. FIG. 5 is a diagram showing the characteristics of the aluminum alloy plate versus temperature after press working of the aluminum alloy plate (Example 1). FIG. 6 is a diagram showing the characteristics of the aluminum alloy plate versus temperature after press working of the aluminum alloy plate (Example 2). FIG. 7 is a diagram showing the characteristics of an aluminum alloy sheet versus the temperature of a short-time baking treatment (Example 3). FIG. 8 is a diagram showing the strength and formability of a 4000 series aluminum alloy sheet and a 6000 series aluminum alloy sheet. FIG. 9 is a diagram showing the characteristics of the aluminum alloy plate after press working.

The following describes the embodiments with reference to the drawings. The configurations of the embodiments are illustrative, and the configuration of the invention is not limited to the specific configurations of the disclosed embodiments. In implementing the invention, specific configurations according to the embodiments may be adopted as appropriate.

[Embodiment]
(Configuration example)
FIG. 1 is a diagram showing an example of the configuration of a die of a press processing device. The die 100 includes an upper die 110 and a lower die 120. The upper die 110 includes an upper die set 111, an upper die wrinkle suppressor 112, and a punch 113. The lower die 120 includes a lower die wrinkle suppressor 121 and a lower die set 122. Here, FIG. 1 is a diagram of the die 100 seen from the front. The direction from left to right in FIG. 1 is the x direction, the direction from the front to the back of the paper (the sail direction from the front to the back of the die 100) is the y direction, and the direction from bottom to top (the direction from the lower die set 122 to the upper die set 111) is the z direction. The upper die set 111 and the lower die set 122 are fixed to the press forming device. The upper die wrinkle suppressor 112 and the punch 113 are fixed to the upper die set 111. The punch 113 deforms the aluminum alloy plate 200 to be processed into a predetermined shape. The shape of the tip of the punch 113 (on the lower die 120 side) is, for example, a cone shape, a column shape, or any other shape. The upper die wrinkle suppressor 112 and the lower die wrinkle suppressor 121 suppress the occurrence of wrinkles in the aluminum alloy plate 200 to be processed. The lower die wrinkle suppressor 121 is fixed to the lower die set. The lower die 120 is disposed opposite to the upper die 110. The aluminum alloy plate (sample material) 200 to be processed is set on the lower die wrinkle suppressor 121. The upper die set 111 has a thermocouple installation hole 140 for installing a thermocouple 310. The lower die set 122 has a cooling water passage 150 for flowing a cooling refrigerant and a thermocouple installation hole 160 for installing a thermocouple 320. The cooling water passage 150 is provided with an inlet and an outlet, and a coolant such as water for cooling the mold 100 is introduced through the inlet and discharged from the outlet. Thermocouples 310 and 320 are installed in the thermocouple installation holes 140 and 160 to measure the temperature of the mold 100. The material of the mold 100 is, for example, steel (tool steel, high speed steel, super steel, etc.). Here, no wrinkle suppression control mechanism is required to suppress shrink flange deformation. The configuration of the mold 100 is not limited to that described here.

As the press processing device, for example, a hydraulic press, a servo press, or a mechanical press is used. A hydraulic press is a press processing device that uses hydraulic pressure to move the die 100 up and down. Compared to other press processing devices, a hydraulic press has a slow processing speed. A servo press is a press processing device that uses a servo motor to move the die 100. A servo press has the characteristic that it is easy to control the speed at the bottom dead center and adjust the holding time. A mechanical press is a press processing device that uses a motor to rotate a flywheel to move the die 100 up and down. It is difficult to finely control the processing speed with a mechanical press. The press processing device can be selected depending on the plate thickness of the aluminum alloy plate 200 and the product shape. For a hydraulic press, high-speed use (processing speed of 20 mm/sec or more) is desirable. For a mechanical press, low-speed use (processing speed of less than 150 mm/sec) is desirable. It is difficult to lengthen the bottom dead center holding time (for example, to 5 seconds or more) in a mechanical press, but in this case, the bottom dead center holding time is set to less than 5 seconds, so a mechanical press can be used.

The upper die 110 (or the lower die 120) moves back and forth between the top dead center and the bottom dead center in the vertical direction due to the operation of the press processing device, so that the upper die 110 and the lower die 120 approach and move away from each other. When the upper die 110 and the lower die 120 approach each other, the punch 113 is pressed against the aluminum alloy sheet 200, and the aluminum alloy sheet 200 is deformed to perform the press processing. The press processing device also includes a die spray sprayer that sprays water or a water-soluble lubricant in a mist toward the upper die 110 and the lower die 120 of the die 100. The die spray sprayer sprays a predetermined amount of mist-like water or water-soluble lubricant onto the upper die 110 and the lower die 120 before the aluminum alloy sheet to be processed is set in the die 100.

In drawing (shrinkage flange deformation), the die 100 generally has a wrinkle suppression control mechanism that controls the pressing of the wrinkle suppressor against the aluminum alloy sheet 200 using a spring or the like. However, when the wrinkle suppression control mechanism is used, the aluminum alloy sheet 200 and the wrinkle suppression control mechanism come into contact during press working, lowering the temperature of the aluminum alloy sheet 200 and resulting in reduced formability. In this case, the wrinkle suppression control mechanism is not used. That is, the contact area of the wrinkle suppression portion 121 of the lower die 120 is reduced as much as possible, and the receiving shape of the punch 113 is present in the lower die 120.

As the material of the mold 100, for example, aluminum alloy (e.g., 5000 series, 7000 series), tool steel (e.g., SKD61, etc.), high speed steel, or super steel is used. 5000 series aluminum alloy is excellent in terms of cost. 7000 series aluminum alloy is excellent in terms of strength. The material of the mold 100 can be selected according to the required characteristics of the processed product. Aluminum alloy, tool steel, high speed steel, or super steel may be used only for the surface layer (processed surface) of the mold 100. The surface of the mold 100 may be left as a polished surface, but in order to prevent adhesion of the aluminum alloy plate 200, it is desirable to perform plating processing such as high hardness chrome plating or nickel plating to form a coating with a low friction coefficient on the surface of the mold 100. For example, electroless nickel plating with a coating thickness of 5-10 μm is desirable. Methods for plating the mold 100 include electrolytic, electroless, and thermal spraying methods, and an appropriate method can be adopted depending on the size of the mold 100. The mold 100 is an example of a steel mold. Steel materials such as tool steel, high-speed steel, and super steel have low thermal conductivity compared to aluminum alloys, but are easy to process and low cost.

2 is a diagram showing an example of a cooling water channel 150 and a thermocouple installation hole 160 provided in the lower die set 122 of the mold 100. The lower die set 122 has a rectangular parallelepiped shape. The cooling water channel 150 has a first portion 151, a second portion 152, and a third portion 153.

In the example of FIG. 2, the inlet, outlet, and thermocouple insertion port of the cooling water channel 150 are provided on the right side of the lower die set 122. The first part 151 of the cooling water channel 150 is a cylindrical water channel extending parallel to the x direction from the inlet. The second part 152 of the cooling water channel 150 is connected to the end opposite the inlet side end of the first part 151 and is a cylindrical water channel extending parallel to the y direction. The third part 153 of the cooling water channel 150 is connected to the end opposite the end connected to the first part 151 of the second part 152 and is a cylindrical water channel extending parallel to the x direction to the outlet. For example, a hose or a pipe is connected to the inlet and outlet of the cooling water channel 150. A coolant such as water is introduced from the inlet of the cooling water passage 150, passes through the first part 151, the second part 152, and the third part 153, and is discharged from the outlet, thereby cooling the lower die set 122. For example, a hose or a pipe is connected to the inlet and outlet of the cooling water passage 150. The lower die set 122 is cooled, thereby cooling the lower die 120 including the lower die wrinkle holder 121. In addition, the upper die 110 that comes into contact with the lower die 120 during pressing can also be cooled. The diameter of the cooling water passage 150 is, for example, 10 mm when the thickness (length in the z direction) of the lower die set 122 is 50 mm.

The thermocouple installation hole 160 is a cylindrical hole extending parallel to the x-direction from a thermocouple insertion port provided on the right side surface of the lower die set 122. The thermocouple installation hole 160 extends to near the center of the lower die set 122. A thermocouple 320 is inserted into the thermocouple installation hole 160 from the thermocouple insertion port. The temperature measurement junction (the part that measures the temperature) of the thermocouple 320 is located near the center of the lower die set 122 within the thermocouple installation hole 160. The temperature of the lower die set 122 of the mold 100 can be measured by the thermocouple 320 inserted into the thermocouple installation hole 160.

The shapes of the cooling water passage 150 and the thermocouple installation hole 160 are not limited to those described here, and may be appropriately changed according to the shape of the mold 100, etc. In addition, multiple cooling water passages may be provided. In addition, multiple thermocouple installation holes may be provided, and the temperature may be measured at multiple positions. The thermocouple installation hole 160 and the thermocouple 310 provided in the upper die set 111 are similar to the thermocouple installation hole 160 and the thermocouple 320 provided in the lower die set 122. Instead of the thermocouple 310 and the thermocouple 320, a thermistor, a resistance temperature detector, a thermo camera, etc. may be used to measure the temperature of the mold 100. By flowing a refrigerant through the cooling water passage 150, the mold 100 is cooled, and the aluminum alloy plate 200 set in the mold 100 is cooled.

Figure 3 is a diagram showing an example of the configuration of a die for a press processing device. In the die 100 of Figure 3, a cooling water passage 130 similar to the cooling water passage 150 of the lower die set 122 is provided in the upper die set 111. The other configurations of the die 100 of Figure 3 are the same as those of the die 100 of Figure 1. By providing cooling water passages in the upper die set 111 and the lower die set 122, the die 100 can be cooled more appropriately. The amount of coolant flowing in the cooling water passage 130 is the same as the amount of coolant flowing in the cooling water passage 150.

(Method of manufacturing aluminum alloy sheet)
Here, a method for manufacturing an aluminum alloy sheet used in the hot stamping method of the present embodiment will be described. The aluminum alloy sheet used here is made from, for example, scrap of a 4000 series aluminum alloy casting (casting product). An aluminum alloy casting is made by pouring an aluminum alloy melted at high temperature into a cavity of a mold and cooling it to solidify.

The 4000 series aluminum alloy (Al-Si alloy) is an aluminum alloy in which silicon (Si) is mainly added to aluminum. The 4000 series aluminum alloy used here is, for example, an aluminum alloy containing 5% or more and less than 11% Si by weight. In addition to solid solution strengthening of the Si-added components, an aluminum alloy containing less than 5% Si has little precipitation hardening due to the Al-Mg-Si system and Al-Cu-Mg-Si system. An aluminum alloy containing 11% or more Si has low rollability and is prone to edge cracking and rolling breakage. Therefore, an aluminum alloy containing 5% or more and less than 11% Si is preferable in terms of rollability and strength characteristics when made into an aluminum alloy plate. In addition, the 4000 series aluminum alloy used here may be, for example, an aluminum alloy containing 5% or more and less than 11% Si by weight, less than 0.6% Mn, less than 0.6% Mg, and less than 2.0% Cu. The 4000 series aluminum alloy used here may be, for example, an aluminum alloy containing, by weight, 5% or more and less than 11% Si, 0.2% or more and less than 0.6% Mn, 0.2% or more and less than 0.6% Mg, and 0.05% or more and less than 2.0% Cu. Mn and Mg contribute to improving the strength of the aluminum alloy. If the amount of Mn or Mg is less than 0.2%, the effect of improving the strength is small. If the amount of Mn or Mg is 0.6% or more, the formation of Al-Mn-based and Al-Fe-Mn-Mg-based compounds and giant compounds is promoted, and the occurrence of cracks during processing is promoted. Therefore, 0.2% or more and less than 0.6% Mn and 0.2% or more and less than 0.6% Mg are preferable. Cu is an element that is particularly effective in improving strength. If the amount of Cu is less than 0.05%, the effect of improving strength is small. If the amount of Cu is 2.0% or more, corrosion resistance is reduced, crack sensitivity is excessively promoted, and delayed fracture after forming is caused. Therefore, Cu is preferably 0.05% or more and less than 2.0%. The 4000 series aluminum alloy is not limited to this. Each aluminum alloy may contain elements other than the elements shown here. For example, Fe, Zn, Ti, etc. may be included. Fe, Zn, Ti, etc. are allowed within a range that does not adversely affect formability. For example, Fe is less than 0.3% to prevent a decrease in formability due to the formation of Al-Fe-based giant compounds. Zn is less than 0.5% to suppress precipitation hardening due to Al-Zn-Mg-based precipitates and prevent stress corrosion cracking. Ti is less than 0.30% to reduce the nuclei of the formation of giant compounds. The JIS component standards for aluminum alloy castings range from AC1B to AC9B depending on the application. These are examples of 4000 series aluminum alloys.

A raw aluminum alloy (for example, a cast product made of a 4000 series aluminum alloy such as AC4A) is melted and cast to produce a slab. At this time, degassing and inclusion removal processes are performed. The degassing process is a process for removing hydrogen gas and the like contained in the molten metal obtained by dissolving the aluminum alloy. The inclusion removal process is a process for removing inclusions such as oxides, carbides, and nitrides contained in the molten metal. If inclusions are contained in the molten metal, problems such as deterioration of castability will occur. In addition, a segregation removal process is performed on the cast slab. The segregation removal process is a process for removing heterogeneous segregation parts generated during casting from the slab. In addition, P or Na in an amount of less than 100 ppm may be added during casting. By adding P or Na, the cast structure of the aluminum alloy is refined.

Next, the slab that has been subjected to the segregation removal treatment is subjected to homogenization heat treatment, which involves heating at a temperature of 450°C or more and less than 540°C. Homogenization heat treatment is a treatment that eliminates the non-uniform distribution of atoms in the slab obtained by casting. In homogenization heat treatment at less than 450°C, the cast structure remains, which leads to edge (end) cracks during hot rolling and reduced workability during cold rolling. In homogenization heat treatment at 540°C or more, burning occurs on the slab surface, and surface defects such as seizure occur on the aluminum alloy plate surface. Therefore, it is preferable that the homogenization heat treatment is performed at a temperature of 450°C or more and less than 540°C. Furthermore, the slab that has been subjected to the homogenization heat treatment is turned into a hot coil with a plate thickness of 2 mm or more and less than 8 mm by hot rolling. The hot coil is an aluminum alloy plate produced by hot rolling that has been wound into a coil shape. In this case, the winding temperature is 270°C or more and less than 350°C. A sheet thickness of less than 2 mm causes friction between the inner and outer surfaces during winding, which can lead to defects. A sheet thickness of 8 mm or more can cause defects due to loose winding. Therefore, the sheet thickness of the hot coil is preferably 2 mm or more and less than 8 mm. If the winding temperature is less than 270°C, recrystallization is insufficient. If the winding temperature is 350°C or more, solid solution strengthening increases, resulting in changes in deformation resistance. An inappropriate winding temperature can cause defects. Therefore, the winding temperature is preferably 270°C or more and less than 350°C.

After this, rough annealing at 300°C or more and less than 400°C is performed, and an aluminum alloy plate having a thickness of 0.8 mm or more and less than 5 mm is produced by cold rolling. The cold rolling is performed, for example, at room temperature (for example, 0°C or more and less than 150°C). Rough annealing leads to prevention of edge (end) cracking during cold rolling. Rough annealing is appropriately performed at a temperature of 300°C or more and less than 400°C as a temperature for softening the aluminum alloy plate. For example, if the hot rolling temperature exceeds 300°C, rough annealing does not need to be performed. After the cold rolling, finish annealing and distortion correction at 330°C or more and less than 400°C may be performed. By performing finish annealing at 330°C or more and less than 400°C, the strength of the aluminum alloy plate is stabilized and residual stress is reduced.

(Example of operation)
FIG. 4 is a diagram showing an example of an operation flow of a hot stamp processing method for an aluminum alloy plate. The aluminum alloy plate is an aluminum alloy plate to be processed. The aluminum alloy plate is, for example, a 4000 series aluminum alloy plate manufactured by the above method. Here, the aluminum alloy plate is processed into a cut plate of an appropriate size for press processing. Here, it is assumed that a die 100 is set in a press processing device, and a refrigerant is flowing in a cooling water passage 150 of the die 100. It is assumed that water as a refrigerant is supplied to the cooling water passage 150 at an amount of 3 L (liters) / min to 15 L / min. When the die 100 is an aluminum alloy, for example, a supply amount of 3 L / min to 10 L / min is appropriate. When the die 100 is a steel material such as tool steel, for example, a supply amount of 7 L / min to 15 L / min is appropriate. During press processing, the internal temperature and surface temperature of the die 100 are maintained at 100 ° C. or less by the refrigerant. The amount of coolant supplied to the cooling water channel 150 may be adjusted according to the temperature of the mold 100 measured by the thermocouple 310 and the thermocouple 320 so that the internal temperature and surface temperature of the mold 100 are 100° C. or less. If the temperature exceeds 100° C., the amount of solid solution of Si, Mg, and Cu in the aluminum alloy plate 200 to be processed decreases, and the cooling time of the aluminum alloy plate 200 becomes longer, resulting in a decrease in productivity. For example, the higher the temperature measured by the thermocouple 310 and the thermocouple 320, the more the amount of coolant supplied to the cooling water channel 150 is increased. If the mold 100 is sufficiently cooled by the mist spray, the cooling by the cooling water channel 150 may be reduced or not performed.

In S101, the aluminum alloy plate 200 to be processed is heated to an ultimate temperature of 450°C or more and less than 560°C for a holding time of less than 10 minutes by a heating furnace such as an electric heater furnace (electric furnace), an induction heating furnace, or an infrared heating furnace. That is, in the heating furnace, the temperature of the aluminum alloy plate 200 is raised to the ultimate temperature, and then the aluminum alloy plate 200 is heated for a holding time of less than 10 minutes at the ultimate temperature. During heating, it is desirable that the temperature difference between the temperatures at each position in the aluminum alloy plate 200 is within a maximum of 40°C. In addition, during heating, it is desirable that the heating rate is 50°C/min or more. The heating rate affects the material structure (crystal grains), and if it is less than 50°C/min, it will lead to a decrease in formability due to crystal grain growth, roughness of the processed surface, and a decrease in productivity. On the other hand, if the temperature distribution width in the material is large, the strength variation will increase, so it is desirable to keep the temperature difference between the temperatures at each position in the aluminum alloy plate 200 within 40°C. The thickness of the aluminum alloy plate is, for example, 0.8 mm or more and less than 5 mm. The ultimate temperature can be changed depending on the type of aluminum alloy.

The reaching temperature is preferably 450°C or more and less than 560°C. If the reaching temperature is less than 450°C, the solid solution of the added components of the aluminum alloy plate is insufficient, making it difficult to increase the strength. Also, if the reaching temperature is 560°C or more, burning (surface dissolution) occurs due to the alloying added elements, which is not preferable. The holding time at the reaching temperature may be 10 minutes or more, but if the holding time at the reaching temperature is long, productivity will decrease significantly, so it is preferable that the holding time at the reaching temperature is less than 10 minutes. In particular, if the reaching temperature is 500°C-560°C, it is preferable that the holding time is shorter. Also, if the reaching temperature is 500°C-560°C, it contributes to improving formability and strength. The shorter the holding time, the more it contributes to improving productivity and energy saving. Also, if the thickness of the aluminum alloy plate is thin (for example, less than 3 mm), there is no problem even if the holding time at the reaching temperature is less than 1 minute, and it is desirable to make it as short as possible. If the thickness of the aluminum alloy plate is less than 0.8 mm, it is not preferable because deformation is likely to occur during transportation, etc. In addition, if the thickness of the aluminum alloy plate is 0.8 mm or more, the deterioration of formability due to temperature drop is small. In addition, even if the thickness of the aluminum alloy plate is 5 mm or more, the processing is possible, but other methods such as extrusion molding are more convenient. In addition, if the thickness of the aluminum alloy plate is 5 mm or more, it takes time to heat before pressing and to cool after pressing, and productivity decreases. Therefore, the thickness of the aluminum alloy plate 200 here is preferably 0.8 mm or more and less than 5 mm.

In S102, the die sprayer of the press machine sprays mist-like water or water-soluble lubricant toward the upper die 110 and the lower die 120 of the die 100. The die sprayer sprays mist-like water or water-soluble lubricant in an amount of 10 mg or more per 100 ^cm2 of the area of the aluminum alloy sheet 200 to be processed toward the upper die 110 and the lower die 120. The die sprayer sprays mist-like water or water-soluble lubricant before the aluminum alloy sheet 200 to be processed is set in the die 100. If the spray amount is less than 10 mg per 100 ^cm2 of the area of the aluminum alloy sheet 200 to be processed, the cooling capacity and lubricating performance are insufficient, leading to adhesion of the aluminum alloy sheet 200 to the die 100. If the spray amount is 3000 mg or more per 100 ^cm2 of the area of the aluminum alloy sheet 200 to be processed, the aluminum alloy sheet 200 is sufficiently cooled, but the water or water-soluble lubricant becomes excessive in the die 100. If there is an excess of water or water-soluble lubricant in the die 100, a draining operation is required to drain the liquid (water or water-soluble lubricant) from the die 100, which leads to deterioration of workability and quality. In addition, an excessive amount of spraying causes strength variations due to temperature unevenness of the aluminum alloy plate 200. Therefore, the amount of spraying is preferably 10 mg or more and less than 3000 mg per 100 ^cm2 of the area of the aluminum alloy plate 200 to be processed. For example, when sufficient cooling is obtained with the cooled die 100, cooling by mist spraying may be reduced or not performed. Spraying of mist by a die sprayer is effective for cooling the aluminum alloy plate 200. The amount of spraying is preferably increased as the thickness of the aluminum alloy plate 200 increases.

In S103, the aluminum alloy sheet 200 heated in S101 is removed from the heating furnace and quickly (for example, within 5 seconds) set on the lower die wrinkle holder 121 of the die 100 of the press processing device. The aluminum alloy sheet is removed from the heating furnace and set in the die 100 by, for example, a well-known robot. The robot has, for example, an arm that holds the aluminum alloy sheet 200, and removes the aluminum alloy sheet 200 that has been heated for a predetermined time from the heating furnace and moves it to the die 100. The robot may also remove the pressed aluminum alloy sheet 200 from the die 100.

In S104, in the press processing device, the upper die 110 of the die 100 is moved to the bottom dead center, and the punch 113 and the upper die wrinkle holder 112 are brought into contact with the aluminum alloy sheet 200, thereby deforming (pressing) the aluminum alloy sheet 200 into a predetermined shape. Here, the press processing speed (processing speed) is 20 mm/s or more and less than 150 mm/s. The press processing speed (processing speed) is the moving speed of the upper die 110 when moving the upper die 110 of the die 100 to the bottom dead center. If the processing speed is less than 20 mm/s, it will lead to a decrease in material temperature (deterioration of deformability), insufficient inflow of lubricant (occurrence of seizure), etc. In addition, if the processing speed is less than 20 mm/s, it will lead to a decrease in productivity. If the processing speed is 150 mm/s or more, the impact load applied to the aluminum alloy sheet 200 will lead to a decrease in formability. For example, local deformation occurs due to sudden contact between the die 100 and the aluminum alloy sheet 200, leading to cracks due to narrowing. Here, the height of the formed product of the drawing process after processing into the aluminum alloy sheet 200 is preferably less than 40 mm. Since no wrinkle suppression control mechanism is used here, if the height of the formed product is 40 mm or more, a shortage of material inflow occurs due to wrinkles in the flange portion. Here, the height of the formed product obtained by shrink flange processing refers to, for example, the dimension of the processed product in the forming direction, that is, the press direction after processing in the press processing. Therefore, if the height of the formed product is 40 mm or more, narrowing or the like may become apparent in the formed product, and the product performance may not be satisfied. If the height of the formed product is 40 mm or more, a wrinkle suppression control mechanism may be used. A blank holder may be used as the wrinkle suppression control mechanism. The blank holder suppresses the occurrence of wrinkles due to the flow of the flange portion of the processed aluminum alloy sheet 200, and promotes the inflow of material required for drawing formation (deep drawing forming (height of the formed product) 40 mm or more). In the hot stamping process, it is desirable not to use a wrinkle suppression control mechanism because it leads to a drop in the temperature of the heated material (aluminum alloy sheet 200). However, for processed products with a high degree of drawing, it is desirable to use a blank holder. When using a blank holder, the aluminum alloy sheet 200 is set directly above the die 100, and it is required to reduce the contact time of the flange portion of the aluminum alloy sheet 200.

In S105, the upper die 110 of the mold 100 is maintained at the bottom dead center, and the aluminum alloy sheet 200 is cooled to 200°C or less. For example, the upper die 110 is maintained at the bottom dead center for 1-5 seconds (bottom dead center holding time 1-5 seconds), and the aluminum alloy sheet 200 is cooled to less than 200°C. If the bottom dead center holding time is less than 1 second, it is difficult to cool the aluminum alloy sheet 200 to less than 200°C. If the aluminum alloy sheet 200 can be cooled to less than 200°C, the bottom dead center holding time may be less than 1 second (for example, less than 0.3 seconds). If the bottom dead center holding time exceeds 5 seconds, productivity is poor. In addition, if the temperature of the aluminum alloy sheet 200 is less than 100°C, the formation of precipitation nuclei (clusters) during aging treatment (such as short-time baking treatment) is small, and the strength tends to decrease slightly. However, in an aluminum alloy containing 5% or more and less than 11% Si by weight, the temperature sensitivity of the molded product is reduced due to the effect of high Si, so the temperature of the aluminum alloy plate 200 may be less than 100°C. In addition, by cooling the aluminum alloy plate 200 to 200°C or less, the flatness of the molded product and the releasability from the mold 100 can be improved by utilizing the temperature difference (thermal shrinkage rate) between the reached temperature of the aluminum alloy plate 200 and the cooling temperature at the bottom dead center. In addition, if the temperature of the aluminum alloy plate 200 exceeds 200°C, there is a problem that the additive elements that increase the strength are precipitated, making it impossible to ensure high strength, and the molded product is likely to deform. Therefore, it is appropriate to cool the aluminum alloy plate 200 until it is 200°C or less. Since the mold 100 is cooled in advance by water cooling or the like, the aluminum alloy plate 200 sandwiched between the upper mold 110 and the lower mold 120 of the mold 100 is also cooled. The temperature of the aluminum alloy sheet 200 is lowered by contacting the die 100, and the temperature difference gives tension to the aluminum alloy sheet 200, contributing to the improvement of flatness. On the other hand, thermal contraction causes the aluminum alloy sheet 200 to stick to the punch 113 side, making it difficult to release. Therefore, it is preferable to optimize the temperature reached by the aluminum alloy sheet 200 to reduce the tension. In addition, when there is a shape that is difficult to release even with the thermal contraction countermeasure of the aluminum alloy sheet 200, for example, it is effective to give a relief angle of several degrees (for example, 1 to 3 degrees) to the punch 113 side, which is the convex side of the die 100, and to reduce the deformation resistance during processing. The deformation resistance is seizure. The deformation resistance is reduced by appropriately combining plating (for example, nickel plating, chrome plating) processing on the die 100 and application of a water-soluble coolant (lubricant). A well-known release agent can be used as the lubricant. Plating on the die 100 can reduce the friction coefficient between the die 100 and the aluminum alloy sheet 200. By providing the die 100 with a convex side relief angle, plating, etc., the dimensional accuracy (flatness, etc.) of the molded product can be improved. In addition, the forced release method can improve the dimensional accuracy of the molded product. The forced release method is a method of releasing the molded product (aluminum alloy sheet 200) from the die 100 by applying a load to a part of the molded product (aluminum alloy sheet 200) by a mechanical method (knockout bar, stripper, etc.) to an extent that the molded product is not deformed. In addition, when the product shape and the thickness of the aluminum alloy sheet 200 are thick (5 mm or more), it is preferable that the bottom dead center holding time is 5 seconds or more. If the temperature of the aluminum alloy sheet 200 is cooled to 200° C. or less within a bottom dead center holding time of 60 seconds, the lack of strength is minimized.

After the press working, the temperature of the aluminum alloy sheet 200 is preferably maintained at 200°C or less for 15 seconds or more. Here, after the press working, the aluminum alloy sheet 200 is taken out of the die 100 and then left in air at room temperature (e.g., about 0°C to 40°C) for 15 seconds or more, for example, to stabilize the structure. In addition, after the press working, another treatment (e.g., cold press working such as trimming, piercing, restriking, etc.) may be performed. By maintaining the temperature of the aluminum alloy sheet 200 at 200°C or less for 15 seconds or more due to the generation of processing heat by the other treatment, the precipitation hardening of Mg ₂ Si, etc. is promoted, the dispersion formation of fine precipitates is increased, and the strength can be improved by artificial aging treatment (short-time baking treatment, long-time baking treatment).

In S106, a short-time baking process is performed on the aluminum alloy plate 200 by heating it at an ultimate temperature of 170°C or more and less than 250°C for a holding time of 20 minutes or more and 120 minutes or less using a heating furnace such as an electric heater furnace (electric furnace), an induction heating furnace, or an infrared heating furnace. That is, the aluminum alloy plate 200 is heated in a heating furnace to an ultimate temperature, and then heated at the ultimate temperature for a holding time of 20 minutes or more and 120 minutes or less. At less than 170°C, precipitation hardening is insufficient, and at 250°C or more, the precipitates become large, precipitation hardening is reduced, and it is difficult to obtain high strength. Therefore, the short-time baking process is preferably at least 170°C and less than 250°C. In addition, it is more preferable that the holding time of the short-time baking process is at least 20 minutes and less than 60 minutes. In addition, instead of the short-time baking process, a long-time baking process may be performed. In the long-term baking treatment, the aluminum alloy plate 200 is heated, for example, at a temperature of 150° C. or more and less than 180° C. for a holding time of 5 hours or more and less than 20 hours (for example, 170° C., 8 hours) in a heating furnace such as an electric heater furnace (electric furnace). The temperature and time of the long-term baking treatment may be determined as conditions that reliably obtain a desired strength, and are not limited to those described here. The short-term baking treatment and the long-term baking treatment are examples of artificial aging treatment. In addition, natural aging (left at room temperature (about 25° C.)) may be performed instead of the artificial aging treatment. The strength of the aluminum alloy plate 200 subjected to the long-term baking treatment is about 380 MPa in tensile strength and about 330 MPa in proof stress. This exceeds the strength of the 6000 series aluminum alloy for forming. Therefore, by using the aluminum alloy plate 200, it is possible to reduce the thickness compared to the case of using the 6000 series aluminum alloy. Moreover, the strength of the aluminum alloy plate 200 subjected to the short-time baking treatment is 330 MPa or more in terms of tensile strength. A tensile strength of 330 MPa or more can be considered to be high strength. By performing the short-time baking treatment, an aluminum alloy plate having a strength equivalent to that obtained by the long-time baking treatment can be obtained. By performing the short-time baking treatment, an aluminum alloy plate having a strength equivalent to that obtained by the long-time baking treatment can be obtained with less energy than the long-time baking treatment. In addition, a molded product whose tensile strength is difficult to measure is evaluated by Vickers hardness. Vickers hardness is measured by a Vickers hardness tester (e.g., a load of 2 kg). In the 4000 series aluminum alloy, a tensile strength of 330 MPa corresponds to a Vickers hardness value of 110 (surface or cross section of the processed product). Therefore, the Vickers hardness of the aluminum alloy plate 200 subjected to the short-time baking treatment is 110 or more.

Example 1
FIG. 5 is a diagram showing the characteristics of an aluminum alloy plate with respect to the temperature after press working of the aluminum alloy plate. Here, as the aluminum alloy plate, scrap (Al-8.9%Si-0.1%Cu-0.4%Mn-0.5%Mg) of a cast part made of AC4A, which is a 4000 series aluminum alloy, is melt-cast, homogenized at 480°C, and then hot-rolled and cold-rolled to produce an aluminum alloy plate having a thickness of 2 mm. Then, a plurality of test materials (JIS No. 5 test pieces) are produced from the 2 mm thick aluminum alloy plate. The produced test materials are subjected to a solution treatment at 550°C for 60 minutes, assuming hot stamping. Furthermore, the test materials are left at room temperature (about 25°C) or are subjected to a heat treatment at 100°C, 150°C, 200°C, or 250°C for 15 minutes. The heat treatment assumes a heat treatment (maintenance treatment) for the aluminum alloy plate after hot stamping. Although the 15-minute heat treatment time is longer than the maintenance time after actual hot stamping, similar strength can be obtained by maintaining the same temperature after actual hot stamping. Then, each test material is subjected to a short-time baking treatment at 180° C. for 20 minutes. The tensile strength, yield strength, and elongation percentage of the test material that has been subjected to the short-time baking treatment are measured.

The test material that was heat-treated at 100°C, 150°C, and 200°C for 15 minutes has a tensile strength of 330 MPa or more. In contrast, the test material that was left at room temperature without heat treatment and the test material that was heat-treated at 250°C for 15 minutes have a tensile strength of less than 330 MPa. In addition, the test material that was baked for a long time (heat-treated at 170°C for 8 hours) after the above solution treatment has a tensile strength of 380 MPa and a yield strength of 330 MPa. The test material that was heat-treated for 15 minutes at 100°C, 150°C, and 200°C can obtain a tensile strength of 90% or more of the test material that was baked for a long time. A tensile strength of 90% or more of the test material that was baked for a long time is sufficient strength. In addition, the elongation rate of each test material is 8% or more, and an elongation rate of 8% or more is a sufficient value. Therefore, it is desirable to maintain the aluminum alloy sheet after hot stamping at 100°C or more and 200°C or less. By performing the short-time baking treatment, an aluminum alloy sheet having the same strength as that obtained by the long-time baking treatment can be obtained in a short time. By performing the short-time baking treatment, the heating treatment time is shortened, and an aluminum alloy sheet having the same strength as that obtained by the long-time baking treatment can be obtained with less energy than the long-time baking treatment.

Example 2
FIG. 6 is a diagram showing the characteristics of an aluminum alloy sheet with respect to the temperature after press working of the aluminum alloy sheet. In Example 1, a short-time baking treatment of 20 minutes at 180° C. was performed, whereas in Example 2, a short-time baking treatment of 20 minutes at 200° C. was performed. The tensile strength, yield strength, and elongation percentage were measured for each test material. In the test materials subjected to heat treatment at 100° C., 150° C., and 200° C. for 15 minutes, the tensile strength was 90% or more of the test materials subjected to long-time baking treatment, and was 330 MPa or more. In addition, even in the test materials that were left at room temperature without heat treatment, the tensile strength was 330 MPa or more. On the other hand, in the test materials subjected to heat treatment at 250° C. for 15 minutes, the tensile strength was less than 330 MPa. In addition, the elongation percentage was 8% or more in each test material, and an elongation percentage of 8% or more is a sufficient value. Here, the test material left at room temperature without heat treatment has a tensile strength of 330 MPa or more, but when Example 1 is taken into consideration, the tensile strength may become less than 330 MPa due to changes in the conditions of the short-time baking treatment. Therefore, it is desirable to maintain the aluminum alloy sheet after hot stamping at 100°C or more and 200°C or less.

Example 3
FIG. 7 is a diagram showing an example of the characteristics of an aluminum alloy sheet with respect to the temperature of a short-time baking treatment. Here, similarly to Example 1, a test material that has been subjected to a solution treatment is subjected to a heat treatment at 150°C for 15 minutes, and then subjected to a short-time baking treatment at 180°C, 200°C, 220°C, 240°C, and 260°C for 20 minutes. The tensile strength, yield strength, and elongation percentage are measured for each test material. The test material that has been subjected to a short-time baking treatment at 180°C, 200°C, and 220°C for 20 minutes has a tensile strength of 330 MPa or more. In contrast, the test material that has been subjected to a short-time baking treatment at 240°C and 260°C for 20 minutes has a tensile strength of less than 330 MPa. The test material that has been subjected to a short-time baking treatment at 240°C and 260°C for 20 minutes has a low tensile strength. Therefore, it is desirable to perform the short-time baking treatment at a temperature of 170°C or more and 230°C or less.

Example 4
FIG. 8 is a diagram showing the strength and formability of a 4000-series aluminum alloy plate and a 6000-series aluminum alloy plate. Here, as the aluminum alloy plate, scrap (Al-7.15%Si-0.05%Cu-0.02%Mn-0.33%Mg) of a cast part made of AC4C material, which is a 4000-series aluminum alloy, is melt-cast and homogenized at 510°C, followed by hot rolling, cold rolling, and finish annealing at 350°C to produce an aluminum alloy plate having a thickness of 2 mm. Then, a test material (JIS No. 5 test piece) is prepared from the 2 mm-thick aluminum alloy plate. The prepared test material is subjected to a solution treatment at 550°C for 60 minutes, assuming hot stamping. In addition, a 6022-T4 material having a thickness of 2 mm, which is a 6000-series aluminum alloy plate, is used as a comparative material. Here, the tensile strength, yield strength, elongation, Erichsen value, and limit drawing ratio (LDR) of the produced 2 mm thick 4000 series aluminum alloy plate (AC4C test material) and 2 mm thick 6000 series aluminum alloy plate (6022-T4 material) are compared. The AC4C test material is inferior in strength and yield strength to the 6022-T4 material. The AC4C test material is a soft material and has a higher elongation than the 6022-T4 material. However, the AC4C test material has a lower Erichsen value (stretchability) than the 6022-T4 material. This is due to the influence of the material structure (crystal grains, eutectic structure, etc.). In addition, the limiting drawing ratio LDR of the AC4C test material and that of the 6022-T4 material are equivalent, but if the strength of the AC4C test material is equivalent to the strength of the 6022-T4 material, the drawing workability (formability) of the AC4C test material is inferior.

(Example 5)
A molding test was carried out on the seat and legs of a chair using a 3 mm thick aluminum alloy plate of the material of Example 4. When molded at room temperature (25°C), the designed shape was not obtained, and cracks occurred when molding the legs. In addition, when processed by hot stamping of the embodiment (solution treatment at 550°C for 60 minutes, lubricant application, water-cooled die, bottom dead center holding time of 2 seconds), both the seat and the legs were good without cracks.

Example 6
FIG. 9 is a diagram showing the characteristics of the aluminum alloy plate after press working of the aluminum alloy plate. Here, as the aluminum alloy plate, scrap of a cast part made of AC4C material, which is a 4000 series aluminum alloy (Al-7.15%Si-0.05%Cu-0.02%Mn-0.33%Mg), is melt-cast and homogenized at 510°C, followed by hot rolling and cold rolling to produce an aluminum alloy plate having a thickness of 2 mm. Then, a test material (JIS No. 5 test piece) is prepared from the 2 mm thick aluminum alloy plate. The prepared test material is subjected to a solution treatment at 550°C for 60 minutes, assuming hot stamping. Furthermore, the test material is water-cooled, left at room temperature (about 25°C) for 120 minutes, baked at 200°C for 20 minutes, or baked at 200°C for 120 minutes. The strength of the test material is measured. AC4C material is a non-heat-treatable alloy and is said not to exhibit precipitation hardening behavior. However, as shown in Figure 9, the AC4C test material can obtain high strength due to precipitation hardening by hot stamping (heating at 500°C or higher followed by rapid cooling and baking at 170°C to 230°C for 20 to 120 minutes) compared to when left at room temperature. The strength of the AC4C test material is equivalent to that of 6022-T4 material, which is also used as an automobile panel material. However, the strength of the AC4C test material is lower than that of AC4A material.

(Functions and Effects of the Embodiments)
In this embodiment, an aluminum alloy plate of a 4000 series aluminum alloy is manufactured using a cast product of an aluminum alloy such as a 4000 series aluminum alloy as a raw material. At this time, for example, scrap material of a cast product of an aluminum alloy is melted and cast to generate a slab. At this time, a degassing treatment and an inclusion removal treatment are performed. Furthermore, a segregation part removal treatment is performed on the cast slab. Furthermore, P or Na in an amount less than 100 ppm may be added during casting. By adding P or Na, the cast structure of the aluminum alloy is refined. Next, a homogenization heat treatment is performed on the slab that has been subjected to the segregation part removal treatment at a temperature of 450 ° C. or more and less than 540 ° C. Furthermore, the slab that has been subjected to the homogenization heat treatment is made into a hot coil with a plate thickness of 2 mm or more and less than 8 mm by a hot rolling treatment. At this time, the coiling temperature is 270 ° C. or more and less than 350 ° C. Furthermore, the aluminum alloy plate 200 is roughly annealed at 300° C. or more and less than 400° C., and then cold-rolled to produce an aluminum alloy plate 200 having a thickness of 0.8 mm or more and less than 5 mm. The aluminum alloy plate 200 is subjected to hot stamping.

In the hot stamping method for the aluminum alloy plate of this embodiment, the aluminum alloy plate 200 is heated in a heating furnace at an attained temperature of 450°C or more and less than 560°C for a holding time of less than 10 minutes. The die 100 is a die made of aluminum alloy, tool steel, high speed steel, super steel, etc. The die 100 is cooled by a refrigerant flowing through the cooling water passage 150. The die 100 is also cooled by mist spray. The heated aluminum alloy plate 200 is taken out of the heating furnace, set in the die 100, and pressed. During the press processing, the aluminum alloy plate 200 is cooled to 200°C or less at the bottom dead center of the die 100. Furthermore, after the press processing, the temperature of the aluminum alloy plate 200 may be maintained at 200°C or less for 15 seconds or more. This allows Si, Mg, and Cu, which contribute to strength, to be solid-dissolved. According to the hot stamp processing method for the aluminum alloy plate of this embodiment, the formability of the aluminum alloy is improved, shapes that have been difficult to form up to now are possible, and the number of steps of the die can be reduced. By cooling the die 100, the temperature of the die 100 can be made less than 200°C. By cooling the die 100, the aluminum alloy plate 200 to be processed can be cooled. By performing a short-time baking process or a long-time baking process on the aluminum alloy plate 200 after press processing, the aluminum alloy plate 200 can be strengthened (tensile strength of 330 MPa or more). By introducing a refrigerant into the die 100 and spraying mist, the aluminum alloy plate can be cooled to a predetermined temperature. In addition, by cooling the aluminum alloy plate 200 to 200°C or less, a molded product with excellent shape freezing properties and flatness can be generated. By cooling through a cooling water channel and spraying mist, direct water cooling of the aluminum alloy plate after press processing can be omitted. By not performing direct water cooling, it is possible to suppress a decrease in press speed, a complication of the die shape, and a complication of the processing process. This makes it possible to improve the productivity and simplification of the press working process.

The hot stamping method for aluminum alloy sheet of this embodiment can produce a pressed product of 4000 series Al-Si alloy with a high Si content. According to this embodiment, a pressed product can be produced from a 4000 series aluminum alloy having strength equal to or greater than that of a 6000 series aluminum alloy. According to this embodiment, a cast product made of a 4000 series aluminum alloy is used as a raw material to produce an aluminum alloy sheet and produce a pressed product, thereby reducing energy consumption compared to the case of producing a pressed product using virgin aluminum ingot. The reduction in energy consumption can lead to a reduction in CO2 emissions.

The above embodiments can be implemented in combination wherever possible.

(Additional Note)
This embodiment may be realized in the following manner.
[Appendix 1]
A heating process in which an aluminum alloy plate made from an aluminum alloy containing 5% or more and less than 11% Si by weight is held at a temperature of 450° C. or more and less than 560° C. for a time of 10 minutes or less;
and a press working step of supplying the aluminum alloy plate to a die and pressing the aluminum alloy plate, and cooling the aluminum alloy plate at a bottom dead center of the press working to 100° C. or higher and 200° C. or lower.
The thickness of the aluminum alloy plate is 1.5 mm or more and less than 5 mm.
Aluminum alloy plate processing method.
[Appendix 2]
A heating step of holding an aluminum alloy plate obtained by casting an aluminum alloy at a temperature of 450°C or higher and lower than 560°C for a period of 10 minutes or less;
and a press working step of supplying the aluminum alloy plate to a die and pressing the aluminum alloy plate, and cooling the aluminum alloy plate at a bottom dead center of the press working to 100° C. or higher and 200° C. or lower.
The thickness of the aluminum alloy plate is 1.5 mm or more and less than 5 mm.
Aluminum alloy plate processing method.
[Appendix 3]
After the press working step, the aluminum alloy plate is maintained at a temperature of 100° C. or more and 200° C. or less for 15 seconds or more.
3. The method for processing an aluminum alloy sheet according to claim 1 or 2.
[Appendix 4]
After the press working step, a baking step of holding the aluminum alloy plate at a temperature of 170 ° C. or more and less than 230 ° C. for 5 minutes to 60 minutes is included.
The method for processing an aluminum alloy sheet according to any one of claims 1 to 3.
[Appendix 5]
After the press working step, a baking step of holding the aluminum alloy plate at a temperature of 150 ° C. or more and less than 180 ° C. for 5 hours or more and 20 hours or less is included.
The method for processing an aluminum alloy sheet according to any one of claims 1 to 3.
[Appendix 6]
The aluminum alloy plate contains, by weight, 5% or more and less than 11% Si, 0.2% or more and less than 0.6% Mg, and 0.01% or more and less than 2.0% Cu.
The method for processing an aluminum alloy sheet according to any one of claims 1 to 5.
[Appendix 7]
The aluminum alloy plate is added with less than 100 ppm of P or less than 100 ppm of Na.
7. A method for processing an aluminum alloy sheet according to claim 6.
[Appendix 8]
The aluminum alloy plate is manufactured by melting and casting the aluminum alloy, and performing a homogenization heat treatment of heating at a temperature of 400° C. or more and less than 500° C., a hot rolling treatment at a temperature of 300° C. or more and less than 400° C. to a thickness of 2 mm or more and less than 8 mm, and a cold rolling treatment to a thickness of 1.5 mm or more and less than 5 mm.
The method for processing an aluminum alloy sheet according to any one of claims 1 to 7.
[Appendix 9]
A spraying step of spraying mist-like water or water-soluble lubricant onto the die in an amount of 10 mg or more and less than 3000 mg per 100 ^cm2 of the aluminum alloy plate,
The bottom dead center holding time in the press working step is 1 second or more and less than 5 seconds.
The method for processing an aluminum alloy sheet according to any one of claims 1 to 8.
[Appendix 10]
The die is provided with a clearance angle on the convex side or is plated.
The method for processing an aluminum alloy sheet according to any one of claims 1 to 9.
[Appendix 11]
A separating step of applying a force to a part of the aluminum alloy plate after the press working step to separate the aluminum alloy plate from the die is included.
The method for processing an aluminum alloy sheet according to any one of claims 1 to 10.

100 Mold 110 Upper die 111 Upper die set 112 Upper die wrinkle holder 113 Punch 120 Lower die 121 Lower die wrinkle holder 122 Lower die set 130 Cooling water channel 140 Thermocouple installation hole 150 Cooling water channel 151 First portion 152 Second portion 153 Third portion 160 Thermocouple installation hole 200 Aluminum alloy plate 310 Thermocouple 320 Thermocouple

Claims (12)

A heating step of holding an aluminum alloy plate made from an aluminum alloy containing 5% or more and less than 11% Si by weight at a temperature of 450° C. or more and less than 560° C. for 10 minutes or less;
and a press working step of supplying the aluminum alloy plate to a die and pressing the aluminum alloy plate, and cooling the aluminum alloy plate to 200° C. or less at a bottom dead center of the press working,
The thickness of the aluminum alloy plate is 0.8 mm or more and less than 5 mm.
Aluminum alloy plate processing method. After the press working step, the aluminum alloy plate is maintained at a temperature of 100° C. or more and 200° C. or less for 15 seconds or more.
The method for processing an aluminum alloy sheet according to claim 1 . After the press working step, a baking step of holding the aluminum alloy plate at a temperature of 170 ° C. or more and less than 250 ° C. for 20 minutes or more and 120 minutes or less is included.
The method for processing an aluminum alloy sheet according to claim 1 . After the press working step, a baking step of holding the aluminum alloy plate at a temperature of 150 ° C. or more and less than 180 ° C. for 5 hours or more and 20 hours or less is included.
The method for processing an aluminum alloy sheet according to claim 1 . The aluminum alloy plate contains, by weight, 5% or more and less than 11% Si, 0.2% or more and less than 0.6% Mg, and 0.01% or more and less than 2.0% Cu.
The method for processing an aluminum alloy sheet according to claim 1 . The aluminum alloy plate is added with less than 100 ppm of P or less than 100 ppm of Na.
The method for working an aluminum alloy sheet according to claim 5 . The aluminum alloy plate is manufactured by melting and casting the aluminum alloy, and performing a homogenization heat treatment of heating at a temperature of 450°C or more and less than 540°C, a hot rolling treatment at a temperature of 300°C or more and less than 400°C to a thickness of 2 mm or more and less than 8 mm, and a cold rolling treatment to a thickness of 0.8 mm or more and less than 5 mm.
The method for processing an aluminum alloy sheet according to claim 1 . A spraying step of spraying mist-like water or water-soluble lubricant onto the die in an amount of 10 mg or more and less than 3000 mg per 100 ^cm2 of the area of the aluminum alloy plate,
The bottom dead center holding time in the press working step is less than 5 seconds.
The method for processing an aluminum alloy sheet according to claim 1 . The die is provided with a clearance angle on the convex side or is plated.
The method for processing an aluminum alloy sheet according to claim 1 . A release step of applying a load to a part of the aluminum alloy plate after the press working step to release the aluminum alloy plate from the die is included.
The method for processing an aluminum alloy sheet according to claim 1 . The press working step is performed by any one of a hydraulic press, a servo press, and a mechanical press,
The processing speed when the die is moved to the bottom dead center is 20 mm/sec or more and less than 150 mm/sec,
The bottom dead center holding time in the press working step is less than 0.3 seconds;
The method for processing an aluminum alloy sheet according to claim 1 . The height of the aluminum alloy plate after the press working step is 40 mm or more,
The press working step includes suppressing occurrence of wrinkles by a wrinkle suppression control mechanism using a blank holder,
The processing speed when the die is moved to the bottom dead center is 20 mm/sec or more and less than 150 mm/sec,
The bottom dead center holding time in the press working step is less than 5 seconds.
The method for processing an aluminum alloy sheet according to claim 1 .

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