JP2023020711A - Processing method of aluminum alloy plate - Google Patents

Abstract

To provide a hot stamp processing technique for an aluminum alloy plate material, for improving productivity.SOLUTION: A processing method of an aluminum alloy plate includes: a heating step of holding an aluminum alloy plate within 10 min at 300°C or more and less than 580°C; and a pressing step of supplying the aluminum alloy plate to a steel material metal mold kept at 120°C or less followed by pressing, and cooling the aluminum alloy plate to 200°C or less at a bottom dead point of the pressing.SELECTED DRAWING: Figure 1

Description

The present invention relates to an aluminum alloy plate processing method.

Aluminum (aluminum alloy) sheet material is effective as a lightweight substitute material for steel sheet products, etc. Since the 1970s, steel beverage cans, stainless steel and copper heat exchangers for air conditioners, etc., and since the 1980s, steel sheet materials for automobile exteriors, etc. has been used as a substitute for Since the 1990s, aluminum sheets have been used for new applications such as battery cases for lithium-ion batteries and liquid crystal semiconductor manufacturing equipment. The use of aluminum sheets for new applications, including these alternatives, is closely related to the progress in processing technology. For example, the development of DI (Drawing and Ironing) processing technology for beverage cans such as beer cans, and the development of brazing technology for heat exchangers have contributed.

JP 2007-284731 A JP-A-9-78210 JP 2014-240085 A JP 2015-199098 A JP 2020-26567 A JP-A-2018-30988

The use of aluminum (aluminum alloying) for automobile outer sheet materials is also an effect of the development of press technology suitable for aluminum sheet materials (forming guideline, optimization of mold shape, lubricant, hemming method, etc.). It is difficult to keep up with sex. Therefore, the use of multi-materials for vehicle bodies is currently being promoted. In addition to the conventional press (cold) technology, the use of hot stamping technology is becoming more prominent for steel sheets, which account for the majority of vehicle body weight. Hot stamping technology is applied to cabin structural parts (super-high-tensile steel sheets) for passenger protection. Similarly, hot stamping technology can be applied to aluminum sheet materials, but it is difficult to obtain cost-competitive aluminum high-strength materials (600 MPa or more) that can compete with ultra-high-strength materials such as steel sheets (1500 MPa or more). , The hot stamping technology for aluminum plate material is only exhibited for the exhibition as a reference technology.

On the other hand, other than pressing aluminum sheets, there are die casting, cold forging, and hot forging technologies. Although these technologies have been adopted by taking advantage of their respective features, no significant progress has been observed in terms of quality and cost in recent years.

Pressed (cold) aluminum plate products are lightweight, excellent in heat dissipation (thermal conductivity), internal quality (no shrinkage cavities or blowholes), and corrosion resistance. However, pressed products made of aluminum sheets are significantly inferior to steel sheets in terms of formability and cost. In addition, pressed aluminum plate products are inferior to die-cast products in terms of flexibility in shape (thickness variation, complex integral molding). Cold forging and hot forging are available as processing methods for aluminum materials that are counter to these methods. Although both methods can greatly increase the degree of freedom in shape, they are more expensive and less productive than cold-pressed products because they require time-consuming heat treatment processes before and after processing. As a technology to improve the press formability of aluminum sheets, there is also development using warm forming technology, but the improvement rate is not high and it is difficult to satisfy the needs. Conventional cold forging and hot forging technologies for aluminum sheets require complicated heat treatment processes before and after processing.

In order to promote the spread of aluminum hot stamping technology, cost competitiveness is important compared to steel plate hot stamping products, and press speeds are being increased. Steel plate hot stamping technology requires rapid cooling immediately after stamping from the viewpoint of strength and shape fixability, and the molded product is directly water-cooled. Therefore, the pressing speed is slow, and a process such as removal of cooling water from the mold is required. Regarding steel plate hot stamping technology, research has been reported on mold cooling technology, adhesion prediction (analysis) technology to molds, mold grades, mold lubricating coatings, and the like. These are effective techniques in steel plate hot stamping technology, but they have a low hot stamping start temperature and do not take into consideration aluminum materials with excellent thermal conductivity. It does not lead to the resolution of the transformation.

SUMMARY OF THE INVENTION An object of the present invention is to provide a hot stamping technique for an aluminum alloy sheet that improves the productivity of a steel mold.

In order to solve the above problems, the following means are adopted.
That is, the first aspect is
a heating step of holding the aluminum alloy plate at a temperature of 300° C. or more and less than 580° C. for a time of 10 minutes or less;
and a pressing step of supplying the aluminum alloy plate to a steel mold maintained at a temperature of 120° C. or less and press working, and cooling the aluminum alloy plate to 200° C. or less at the bottom dead center of the press working. An aluminum alloy plate processing method.

ADVANTAGE OF THE INVENTION According to this invention, the hot-stamping technique of the aluminum-alloy board material which improves the productivity by a steel material metal mold|die can be provided.

FIG. 1 is a diagram showing a configuration example of a die of a press working apparatus. FIG. 2 is a diagram showing an example of cooling water channels 150 and thermocouple installation holes 160 provided in the lower die set 122 of the mold 100. As shown in FIG. FIG. 3 is a diagram showing a configuration example of a die of the press working device. FIG. 4 is a diagram showing an example of an operation flow of a method for hot stamping an aluminum alloy plate. FIG. 5 is a diagram showing an example of the lower mold of the simulated mold 900 used in the examples. FIG. 6 shows the temperature of the simulated mold 900, the temperature difference (water temperature difference) between the water temperature at the inlet and the water temperature at the outlet of the cooling water channel 930, and FIG. 4 is a diagram showing the temperature of an aluminum alloy plate after mist spraying; FIG. 7 shows the temperature of the simulated mold and the mist when changing the amount of mist sprayed to the simulated mold by the mold sprayer and the mist sprayed to the aluminum alloy plate by the aluminum alloy plate sprayer. FIG. 4 is a diagram showing the temperature of the aluminum alloy plate after spraying;

Embodiments will be described below with reference to the drawings. The configuration of the embodiment is an example, and the configuration of the invention is not limited to the specific configuration of the disclosed embodiment. In carrying out the invention, a specific configuration according to the embodiment may be adopted as appropriate.

[Embodiment]
(Configuration example)
FIG. 1 is a diagram showing a configuration example of a die of a press working apparatus. A mold 100 includes an upper mold 110 and a lower mold 120 . The upper mold 110 includes an upper mold die set 111 , an upper mold wrinkle holder 112 and a punch 113 . The lower die 120 includes a lower die wrinkle holding portion 121 and a lower die set 122 . Here, FIG. 1 is a diagram of the mold 100 viewed from the front. The direction from left to right in FIG. to the upper die set 111) is the z-direction. The upper die set 111 and the lower die set 122 are fixed to a press molding device. The upper die wrinkle holding portion 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 side of the lower die 120) is, for example, a conical shape, a columnar shape, or an arbitrary shape. The upper die wrinkle suppressing part 112 and the lower die wrinkle suppressing part 121 suppress the occurrence of wrinkles in the aluminum alloy plate 200 to be processed. The lower die wrinkle holding portion 121 is fixed to the lower die set. The lower mold 120 is arranged to face the upper mold 110 . An aluminum alloy plate (test material) 200 to be processed is set on the lower die wrinkle holding portion 121 . The upper die set 111 has a thermocouple installation hole 140 for installing the thermocouple 310 . In addition, the lower die set 122 has a cooling water channel 150 through which a cooling coolant flows, and a thermocouple installation hole 160 for installing the thermocouple 320 . The cooling water channel 150 is provided with an inlet and an outlet, and a coolant such as water for cooling the mold 100 is introduced from the inlet and discharged from the outlet. A thermocouple 310 and a thermocouple 320 are installed in the thermocouple installation hole 140 and the thermocouple installation hole 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, a wrinkle holding control mechanism for suppressing shrinkage flange deformation is not required. The configuration of mold 100 is not limited to that described herein.

The upper die 110 (or the lower die 120) reciprocates in the vertical direction between the top dead center and the bottom dead center due to the operation of the press working device, so that the upper die 110 and the lower die 120 approach or move away from each other. do. When the upper die 110 and the lower die 120 approach each other, the punch 113 is pressed against the aluminum alloy plate 200, and the aluminum alloy plate 200 is deformed and pressed. In addition, the press working apparatus includes a mold sprayer that turns water or a water-soluble lubricant into a mist and sprays it toward the upper mold 110 and the lower mold 120 of the mold 100 . The mold sprayer sprays a predetermined amount of water mist or water-soluble lubricant onto the upper mold 110 and the lower mold 120 before the aluminum alloy plate to be processed is set in the mold 100 .

In the drawing process (shrink flange deformation), the die 100 generally has a wrinkle holding control mechanism for controlling the wrinkle holding to be pressed against the aluminum alloy plate 200 by a spring or the like. However, if the wrinkle-holding control mechanism is used, the aluminum alloy plate 200 and the wrinkle-holding control mechanism may come into contact with each other during press working, lowering the temperature of the aluminum alloy plate 200 and causing deterioration in formability. Here, no wrinkle control mechanism is used. That is, the contact portion of the wrinkle holding portion 121 of the lower die 120 is reduced as much as possible, and the receiving shape of the punch 113 exists in the lower die 120 .

As a material for the mold 100, for example, tool steel (such as SKD61), high-speed steel, or steel such as super steel is used. Steel materials such as tool steel, high-speed steel, and super steel may be used only for the surface layer portion (working 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, a plating process such as high-hardness chromium plating or nickel plating is applied to the surface of the mold 100 to reduce friction. It is desirable to form a modulus coating. For example, electroless nickel plating with a film thickness of 5-10 μm is desirable. Methods of plating the mold 100 include electrolysis, electroless, thermal spraying, and the like.
An appropriate method can be adopted as appropriate depending on the size of the mold 100 and the like. The mold 100 is an example of a steel mold. Steel materials such as tool steel, high-speed steel, and super steel have lower thermal conductivity than aluminum alloys, but are easy to process and low in cost.

Also, a spray atomizer for aluminum alloy plates is provided in the vicinity of the press working device. The aluminum alloy plate sprayer sprays a predetermined amount of water mist or a water-soluble lubricant onto the pressed aluminum alloy plate (molded product).

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

In the example of FIG. 2, the right side surface of the lower die set 122 is provided with the inlet and outlet of the cooling water channel 150 and the thermocouple inlet. A first portion 151 of the cooling channel 150 is a cylindrical channel extending parallel to the x-direction from the inlet. The second portion 152 of the cooling channel 150 is a cylindrical channel that is connected to the end of the first portion 151 opposite to the inlet side end and extends parallel to the y-direction. The third portion 153 of the cooling channel 150 is a cylindrical channel connected to the end of the second portion 152 opposite to the end connected to the first portion 151 and extending in parallel to the x-direction to the outlet. For example, hoses and pipes are 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 channel 150, passes through the first portion 151, the second portion 152, and the third portion 153, and is discharged from the outlet, thereby cooling the lower die set 122. be. For example, hoses and pipes are connected to the inlet and outlet of the cooling water channel 150 . By cooling the lower die set 122, the lower die 120 including the lower die wrinkle holding portion 121 is cooled. Also, the upper mold 110 that contacts the lower mold 120 during pressing can be cooled. The diameter of the cooling channel 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 opening 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 a thermocouple insertion port. A temperature-measuring junction (a portion for measuring temperature) of the thermocouple 320 is arranged 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 channel 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 and the like. Also, a plurality of cooling channels may be provided. Also, a plurality of thermocouple installation holes may be provided to measure the temperature at a plurality of positions. The thermocouple installation hole 160 and thermocouple 310 provided in the upper die set 111 are similar to the thermocouple installation hole 160 and thermocouple 320 provided in the lower die set 122 . Instead of the thermocouples 310 and 320, a thermistor, a resistance temperature detector, a thermocamera, or the like may be used to measure the temperature of the mold 100. FIG. The mold 100 is cooled by flowing the coolant through the cooling water channel 150, and the aluminum alloy plate 200 set in the mold 100 is cooled.

FIG. 3 is a diagram showing a configuration example of a die of the press working device. In the mold 100 of FIG. 3, the upper die set 111 is provided with cooling water channels 130 similar to the cooling water channels 150 of the lower die set 122 . Other configurations of the mold 100 of FIG. 3 are the same as those of the mold 100 of FIG. By providing cooling water channels in the upper die set 111 and the lower die set 122, the mold 100 can be cooled more appropriately. The amount of refrigerant flowing through cooling waterway 130 is the same as the amount of refrigerant flowing through cooling waterway 150 .

(Operation example)
FIG. 4 is a diagram showing an example of an operation flow of a method for hot stamping an aluminum alloy plate. An aluminum alloy plate is an aluminum alloy plate to be processed. The aluminum alloy plate is, for example, a cut plate after rolling or after rolling and solution treatment. Rolling treatment means hot rolling treatment (and cold rolling treatment) in the manufacturing process of aluminum alloy. Solution treatment is a process of rapidly cooling from a temperature at which alloy components are dissolved in an aluminum alloy. Solution treatment, for example, continuous annealing line (CAL: Continuous Annealing Line)
performed by Here, it is assumed that the mold 100 is set in the press working device, and the cooling water channel 150 of the mold 100 is supplied with a coolant. It is assumed that the cooling water passage 150 is supplied with water as a refrigerant in an amount of 2 L (liter)/minute to 15 L/minute. During press working, the coolant maintains the internal temperature and surface temperature of the mold 100 at 100° C. or less, preferably 50° C. or less. Depending on the temperature of the mold 100 measured by the thermocouples 310 and 320, the temperature of the mold 100 is supplied to the cooling water channel 150 so that the internal temperature and surface temperature of the mold 100 are 100 ° C. or less or 50 ° C. or less. The amount of refrigerant may be adjusted. For example, the higher the temperature measured by the thermocouples 310 and 320, the greater the amount of coolant supplied to the cooling water passage 150. FIG. When the mold 100 is sufficiently cooled by mist spraying, cooling by the cooling water passage 150 may not be performed.

Here, aluminum alloys include 1000 series aluminum alloys, 2000 series aluminum alloys, 3000 series aluminum alloys, 4000 series aluminum alloys, 5000 series aluminum alloys, 6000 series aluminum alloys, and 7000 series aluminum alloys. Aluminum alloys are not limited to those listed here. 1000 series aluminum is pure aluminum with a purity of 99.00% or more. Here, 1000-series aluminum is also a kind of aluminum alloy. A 2000 series aluminum alloy (Al—Cu series alloy) is an aluminum alloy in which copper (Cu) is mainly added to aluminum. A 3000 series aluminum alloy (Al—Mn series alloy) is an aluminum alloy in which manganese (Mn) is mainly added to aluminum. A 4000 series aluminum alloy (Al—Si series alloy) is an aluminum alloy in which silicon (Si) is mainly added to aluminum. A 5000 series aluminum alloy (Al—Mg series alloy) is an aluminum alloy in which magnesium (Mg) is mainly added to aluminum. A 5000 series aluminum alloy is an aluminum alloy containing, for example, 2% or more and less than 5% by weight of Mg. The 5000 series aluminum alloy is not limited to this. A 6000 series aluminum alloy (Al--Mg--Si series alloy) is an aluminum alloy in which magnesium and silicon are mainly added to aluminum. The 6000 series aluminum alloy contains, for example, 0.4% or more and less than 1.0% Mg, 0.7% or more and less than 1.5% Si, and 0.01% or more and less than 0.2% Cu It is an aluminum alloy containing The 6000 series aluminum alloy is not limited to this. A 7000 series aluminum alloy (Al--Zn--Mg alloy) is an aluminum alloy in which zinc (Zn) and magnesium are mainly added to aluminum. A 7000 series aluminum alloy is an aluminum alloy containing, for example, 5.0% or more and less than 9.0% of Zn and 1.3% or more and less than 2.5% of Cu, by weight. The 7000 series aluminum alloy is not limited to this. Each aluminum alloy may contain elements other than those shown here.

In S101, the aluminum alloy plate 200 to be processed is held at a temperature of 300° C. or more and less than 580° C. for 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. Heat up in time. That is, after raising the temperature of the aluminum alloy plate 200 to the target temperature in the heating furnace, the aluminum alloy plate 200 is further heated at the target temperature for a holding time of less than 10 minutes. During heating, it is desirable that the temperature difference between the respective positions in the aluminum alloy plate 200 is within 40°C at maximum. Also, when heating
A heating rate of 50° C./min or more is desirable. The heating rate affects the material structure (crystal grains), and if it is less than 50° C./min, it leads to a decrease in formability due to grain growth, a rough surface on the processed surface, and a decrease in productivity. On the other hand, if the width of the temperature distribution in the material is wide, the strength variation becomes large. The thickness of the aluminum alloy plate is, for example, 1.5 mm or more and less than 5 mm. The ultimate temperature can be changed depending on the type of aluminum alloy. The temperature reached is, for example, 300° C.-500° C. for 3000 series aluminum alloys, 300° C.-450° C. for 5000 series aluminum alloys, and 400° C.-550° C. for 6000 series aluminum alloys. If the ultimate temperature is less than 300°C, the ductility of the aluminum alloy sheet is insufficient, and the degree of improvement in formability is low. Moreover, if the temperature reaches 580° C. or higher, burning (melting state) occurs due to the alloying additive elements, which is not preferable. The retention time at the reached temperature may be 10 minutes or more, but if the retention time at the reached temperature is long, the productivity will be greatly reduced, so the retention time at the reached temperature is preferably less than 10 minutes. If the thickness of the aluminum alloy plate is thin (for example, less than 3 mm), the holding time at the reached temperature can be less than 1 minute without any problem, and it is desirable to make it as short as possible. If the thickness of the aluminum alloy plate is less than 1.5 mm, it is not preferable because it is likely to be deformed during transportation. Also, even if the thickness of the aluminum alloy plate is 5 mm or more, the processing is possible, but other methods such as extrusion are more convenient. Therefore, the thickness of the aluminum alloy plate 200 here is preferably 1.5 mm or more and less than 5 mm.

In S<b>102 , the mold sprayer of the press machine sprays water or a water-soluble lubricant in the form of mist toward the upper mold 110 and the lower mold 120 of the mold 100 . The mold sprayer sprays water or a water-soluble lubricant in the form of mist in an amount of 10 mg or more per 100 cm ² of area of the aluminum alloy plate 200 to be processed to the upper mold 110 and the lower mold 120 . Mist water or water-soluble lubricant is sprayed by the mold sprayer before the aluminum alloy plate 200 to be processed is set in the mold 100 . If the spray amount is less than 10 mg per 100 cm ² area of the aluminum alloy plate 200 to be processed, the cooling capacity and lubricating performance are insufficient, causing adhesion of the aluminum alloy plate 200 to the mold 100 . Further, when the spray amount is 2000 mg or more per 100 cm ² of the area of the aluminum alloy plate 200 to be processed, the mold 100 is sufficiently cooled, but the water or water-soluble lubricant becomes excessive. Excess water or water-soluble lubricant in the mold 100 requires draining work to remove the liquid (water or water-soluble lubricant) from the mold 100, resulting in deterioration of workability and quality. Therefore, the spray amount is preferably 10 mg or more and less than 2000 mg per 100 cm ² area of the aluminum alloy plate 200 to be processed. Cooling by mist spray may not be performed.

In S103, the aluminum alloy plate 200 heated in S101 is taken out from the heating furnace and quickly (for example, within 5 seconds) is set on the lower mold wrinkle holder 121 of the mold 100 of the press machine. Taking out the aluminum alloy plate from the heating furnace and setting it in the mold 100 is performed by, for example, a well-known robot or the like. The robot has, for example, an arm that grips the aluminum alloy plate 200 , takes out the aluminum alloy plate 200 heated for a predetermined time from the heating furnace, and moves it to the mold 100 . Further, the robot may take out the pressed aluminum alloy plate 200 from the mold 100 .

In S104, in the press machine, the upper die 110 of the die 100 is moved to the bottom dead center, and the punch 113 and the upper die wrinkle holding portion 112 are brought into contact with the aluminum alloy plate 200, so that the aluminum alloy plate 200 is pressed to a predetermined level. deformed (pressed) into the shape of Here, it is preferable that the height of the drawn product after processing into the aluminum alloy plate 200 is less than 40 mm. Since the wrinkle holding control mechanism is not used here, when the height of the molded product is 40 mm or more, insufficient material flow occurs due to wrinkles in the flange portion. Here, the height of the molded product refers to, for example, the dimension of the processed product in the molding direction, ie, the press direction after processing in press working. Therefore, if the height of the molded product is 40 mm or more, constriction or the like may appear in the molded product, and the product performance may not be satisfied.

In S105, the upper mold 110 of the mold 100 is maintained at the bottom dead center, and the aluminum alloy plate 200 is cooled to 200° C. or less. For example, the aluminum alloy plate 200 is cooled to 200° C. or less by maintaining the upper die 110 at the bottom dead center for 1 to 10 seconds (bottom dead center holding time of 1 to 10 seconds). 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. If the temperature of the aluminum alloy plate 200 exceeds 200° C., the additional elements that increase the strength are precipitated, and high strength cannot be ensured, and deformation of the molded product is likely to occur. In addition, by cooling the aluminum alloy plate 200 to 200 ° C. or less, the temperature difference (thermal contraction rate) between the ultimate temperature of the aluminum alloy plate 200 and the cooling temperature at the bottom dead center is used to improve the flatness of the molded product. and the releasability from the mold 100 can be improved. The temperature of the aluminum alloy plate 200 is lowered by contact with the mold 100, and the temperature difference imparts tension to the aluminum alloy plate 200, contributing to improvement in flatness. The lower the temperature at the bottom dead center, the better. On the other hand, heat shrinkage causes the aluminum alloy plate 200 to stick to the punch 113 side, making release difficult. Therefore, it is preferable to reduce the tension by optimizing the ultimate temperature of the aluminum alloy plate 200 . In addition, if there is a shape that is difficult to release from the aluminum alloy plate 200 even as a countermeasure against heat shrinkage, for example, a relief angle of several degrees (for example, 0 to 5 degrees) is given to the punch 113 side, which is the convex side of the mold 100. In addition, it is effective to reduce deformation resistance during processing. Deformation resistance is seizure. Deformation resistance is reduced by appropriately combining plating (for example, nickel plating, chromium plating) on the mold 100 and applying a water-soluble coolant (lubricant). Known release agents can be used as lubricants. Plating the mold 100 can reduce the coefficient of friction between the mold 100 and the aluminum alloy plate 200 .

In S106, a mist of water or a water-soluble lubricant is directly sprayed onto the aluminum alloy plate 200 placed on the mold 100 by an aluminum alloy plate sprayer provided near the press machine. After that, the aluminum alloy plate 200 is removed from the mold 100 . Alternatively, the aluminum alloy plate 200 is taken out from the mold 100, and a mist of water or a water-soluble lubricant is sprayed toward the taken out aluminum alloy plate 200 by an aluminum alloy plate spray atomizer provided near the press machine. to spray. When the aluminum alloy plate 200 is removed from the mold 100 and sprayed, the aluminum alloy plate 200 is placed in a container such as a bucket that is larger than the aluminum alloy plate 200, and water or water-soluble lubricant is misted in the container. agent is sprayed. The aluminum alloy plate spray atomizer sprays 1 g or more of water mist or a water-soluble lubricant onto the aluminum alloy plate 200 per 100 cm ² of the area of the aluminum alloy plate 200 . The spraying time is, for example, within 3 seconds. The reason for setting the spraying time within 3 seconds is to ensure productivity. The mist-like water or water-soluble lubricant is sprayed by the aluminum alloy plate spray atomizer directly onto the aluminum alloy plate 200 placed on the mold 100, or after the aluminum alloy plate 200 is removed from the mold 100. done. If the spray amount is less than 1 g per 100 cm ² of aluminum alloy plate 200, the cooling capacity is insufficient, and it is difficult to cool aluminum alloy plate 200 sufficiently. Further, when the spray amount is 5 g or more per 100 cm ² of the area of the aluminum alloy plate 200 to be processed, the water or water-soluble lubricant is excessive although the cooling is sufficient. Excessive amount of water or water-soluble lubricant in the mold 100 increases the burden of treatment such as drainage, resulting in deterioration of workability. Therefore, the spray amount is preferably 1 g or more and less than 5 g per 100 cm ² area of the aluminum alloy plate 200 to be processed. If the aluminum alloy plate 200 is sufficiently cooled in S105, cooling by mist spraying to the aluminum alloy plate 200 may not be performed. The aluminum alloy plate spray atomizer may be the same as the mold spray atomizer.

Further, the aluminum alloy plate 200 is strengthened by performing natural aging (leaving at room temperature (approximately 25° C.)) or artificial aging treatment (heating). For example, higher strength can be obtained by performing artificial aging treatment by heating at 100° C. or more and less than 200° C. Also, the artificial aging treatment may be performed after other treatments after the treatment of the aluminum alloy plate 200 in S101 to S106 described above. For non-precipitation hardened aluminum alloy sheets (e.g., 1000 series, 3000 series, 5000 series, etc.), consider the dimensional accuracy of other processes after press working (e.g., piercing, trimming, etc.). It is desirable that the temperature of the subsequent aluminum alloy plate 200 is 100° C. or lower.

(Example)
FIG. 5 is a diagram showing an example of the lower mold of the simulated mold 900 used in the examples. A simulated mold 900 is a mold that simulates the mold 100 . Here, FIG. 5 is a view of the lower mold of the simulated mold 900 viewed from above. The direction from left to right in FIG. 5 is the x direction, the direction from the bottom to the top is the y direction, and the direction from the front side to the back side of the paper (the direction from the bottom to the top of the simulated mold 900) is the z direction. A simulated mold 900 includes an upper mold and a lower mold. The outer shape of the upper and lower molds is a rectangular parallelepiped with a width of 200 mm (x direction), a depth of 200 mm (y direction), and a height of 50 mm (z direction). A lower mold of the simulated mold 900 includes a cooling channel 930 , a first thermocouple installation hole 941 , a second thermocouple installation hole 942 and a recess 950 . The cooling channel 930 has a first portion 931 , a second portion 932 and a third portion 933 . A recess 950 is provided in the center of the upper surface of the simulated mold 900 . The shape of the recess 950 is a rectangular parallelepiped with a width of 50 mm (x direction), a depth of 50 mm (y direction), and a depth of 10 mm (z direction). The lower side of the lower mold 900 of FIG. 5 is the front side, the right side is the right side, the left side is the left side, and the upper side is the back side. Also, the upper side of the lower mold of the simulated mold 900 is the upper surface, and the lower side thereof is the lower surface. Here, the simulated mold 900 is a steel mold made of tool steel (SKD61).

An inlet and an outlet of a cooling channel 930 are provided on the right side of the lower mold of the simulated mold 900 . The inlet and outlet are circular, for example. The center of the inlet is, for example, 37.5 mm from the front and 25 mm from the top. The center of the outlet is, for example, 37.5 mm from the back surface and 25 mm from the top surface. A first portion 931 of the cooling channel 930 is a cylindrical channel extending parallel to the x-direction from the inlet. The length of the first portion 931 is, for example, 162.5 mm. A second portion 932 of the cooling channel 930 is a cylindrical channel that is connected to the end of the second portion 931 opposite to the inlet side end and extends parallel to the y-direction. The length of the second portion 932 is, for example, 125 mm. A third portion 933 of the cooling channel 930 is a cylindrical channel connected to the end of the second portion 932 opposite to the end connected to the first portion 931 and extending in parallel to the x-direction to the outlet. The length of the third portion 933 is, for example, 162.5 mm. For example, hoses and pipes are connected to the inlet and outlet of the cooling water channel 930 . The diameter of the cooling channel 930 is, for example, 10 mm.

The first thermocouple installation hole 941 is a cylindrical hole extending parallel to the x direction from a thermocouple insertion opening provided on the right side surface of the lower mold of the simulated mold 900 . The center of the thermocouple insertion port is, for example, 100 mm from the front and 10 mm from the top. The second thermocouple installation hole 941 extends to near the center of the lower die. The length of the first thermocouple installation hole 941 is, for example, 70 mm. The second thermocouple installation hole 942 is a cylindrical hole extending parallel to the x-direction from a thermocouple insertion opening provided on the right side surface of the lower mold of the simulated mold 900 . The center of the thermocouple insertion port is, for example, 58.75 mm from the front and 10 mm from the top. The second thermocouple installation hole 942 extends to near the center of the lower die. The length of the second thermocouple installation hole 941 is, for example, 100 mm. The diameter of the first thermocouple installation hole 941 and the second thermocouple installation hole 942 is, for example, 5 mm. Thermocouples are inserted into the first thermocouple installation hole 941 and the second thermocouple installation hole 942 from thermocouple insertion openings. Thermocouple temperature-measuring junctions (parts for measuring temperature) are arranged near the center of the simulated mold 900 in the first thermocouple installation hole 941 and the second thermocouple installation hole 942, respectively. The temperature of the mold 900 can be measured by the thermocouples inserted into the first thermocouple installation hole 941 and the second thermocouple installation hole 942 . Since the simulated mold 900 is metal and has high thermal conductivity, the internal temperature of the simulated mold 900 measured by a thermocouple may be regarded as the surface temperature of the simulated mold 900 (the temperature of the simulated mold 900). In the measurement examples shown below, the temperature of the simulated mold 900 is the temperature of the thermocouple inserted into the first thermocouple installation hole 941, and the temperature of the thermocouple inserted into the second thermocouple installation hole 942 is It is the average of the temperatures measured by the thermocouple. In the measurement examples shown below, the temperature of the thermocouple inserted into the first thermocouple installation hole 941 and the temperature of the thermocouple inserted into the second thermocouple installation hole 942 were substantially the same.

<Measurement example>
An example of temperature measurement using the simulated mold 900 is shown. Here, a 150 mm square, 4 mm thick rolled material (aluminum alloy plate) of 5052 alloy (Al-2.5% Mg-0.2% Cr) is heated to 500°C. A heated aluminum alloy plate is set in the center of the lower mold of the simulated mold 900, and the upper mold of the simulated mold 900 is placed thereon. That is, the aluminum alloy plate is sandwiched (inserted) between the lower mold and the upper mold of the simulated mold 900 . Water as a coolant can be supplied from 2 L/min to 15 L/min to the cooling water channel 930 of the simulated mold 900 . The material of the simulated mold 900 is tool steel (SKD61). Here, assuming press working, an aluminum alloy plate is sandwiched (inserted) between the lower die and the upper die of the simulated die 900, and the aluminum alloy plate is inserted between the lower die and the upper die of the simulated die 900. Repeat removing the plate. The aluminum alloy plates are inserted and taken out one by one. Here, assuming that one aluminum alloy plate is pressed four times and the holding time at the bottom dead center is 5 seconds per press, the holding time at the bottom dead center is 20 seconds (the time to sandwich the aluminum alloy plate). To stabilize the furnace temperature, the temperature of the simulated mold 900 and the temperature of the aluminum alloy plate after removal are measured by setting the working time (time interval of removal from the furnace) for one aluminum alloy plate to 60 seconds. The temperature of the simulated mold 900 is measured by thermocouples inserted into the first thermocouple installation hole 941 and the second thermocouple installation hole 942 . In the initial state (before measurement), the temperature of the simulated mold 900 is 15.degree.

FIG. 6 shows the temperature of the simulated mold 900, the temperature difference (water temperature difference) between the water temperature at the inlet and the water temperature at the outlet of the cooling water channel 930, and FIG. 4 is a diagram showing the temperature of an aluminum alloy plate after mist spraying; A description will be given of the case where the amount of water of the refrigerant flowing through the cooling water passage 930 is set to 2 L/min, 5 L/min, 10 L/min, and 15 L/min. Here, before inserting the aluminum alloy plate, 500 mg of mist per 100 cm ² area of the aluminum alloy plate is sprayed onto the upper and lower dies of the simulated mold 900 by a mold sprayer. Furthermore, after the aluminum alloy plate is removed from the simulated mold 900, 2 g of mist per 100 cm ² of aluminum alloy plate area is sprayed on the aluminum alloy plate for 2 seconds by an aluminum alloy plate sprayer. Here, water is used as the mist. The temperature and temperature difference shown in FIG. 6 are the temperature and temperature difference after inserting 10 to 20 aluminum alloy plates.

The temperature of the simulated mold 900 decreases as the amount of coolant flowing through the cooling water passage 930 increases. The temperature difference between the water temperature at the inlet and the water temperature at the outlet of cooling water passage 930 decreases as the amount of coolant flowing through cooling water passage 930 increases. In particular, when it exceeds 5 L/min, the temperature difference almost disappears. Further, the temperature of the aluminum alloy plate after the mist is sprayed decreases as the amount of water of the coolant flowing through the cooling water passage 930 increases. The temperature of the aluminum alloy plate here does not include the temperature rise due to the working heating of the actual press working. Here, it is assumed that the actual temperature rise due to heating during press working is 70°C. Therefore, in order to set the temperature of the aluminum alloy plate to 200° C. or lower during the actual press working, the temperature of the aluminum alloy plate should be 130° C. or lower. At 2 L/min and 5 L/min, the temperature of the aluminum alloy plate exceeds 130°C. Therefore, here, the amount of water of the refrigerant flowing through the cooling water passage 930 is preferably 10 L/min and 15 L/min. If the flow rate exceeds 15 L/min, leaks and the like are likely to occur, which is not preferable.

FIG. 7 shows the temperature of the simulated mold and the mist when changing the amount of mist sprayed to the simulated mold by the mold sprayer and the mist sprayed to the aluminum alloy plate by the aluminum alloy plate sprayer. FIG. 4 is a diagram showing the temperature of the aluminum alloy plate after spraying; The amount of coolant flowing through the cooling water channel 930 was set to 10 L/min. Here, the spray amount to the mold (simulated mold 930) and the spray amount to the aluminum alloy plate are (1) 50 mg/100 cm ² , 0 g/100 cm ² (no spray), and (2) 500 mg/100 cm ² . , 0 g/100 cm ² (without spraying), (3) 500 mg/100 cm ² , 2 g/100 cm ² , (4) 5000 mg/100 cm ² , 5 g/100 cm ² , temperature of simulated mold 900, aluminum alloy plate was measured. Here, prior to inserting the aluminum alloy plate, mist is sprayed onto the upper and lower molds of the simulated mold 900 by a mold sprayer. Further, after the aluminum alloy plate is taken out from the simulated mold 900, mist is sprayed on the aluminum alloy plate for 2 seconds by a spray atomizer for aluminum alloy plate. Here, water is used as the mist. The temperature shown in FIG. 7 is the temperature after inserting 10 to 20 aluminum alloy plates.

The temperature of the simulated mold 900 decreases as the amount of mist sprayed onto the simulated mold 900 increases. Also, the temperature of the simulated mold 900 decreases as the amount of mist sprayed onto the aluminum alloy plate increases. Further, the temperature of the aluminum alloy plate after mist is sprayed decreases as the amount of mist sprayed onto the simulated mold 900 increases. Further, the temperature of the aluminum alloy plate after spraying the mist becomes lower as the amount of mist sprayed onto the aluminum alloy plate increases. When the amount of mist sprayed onto the simulated mold 900 is 50 mg/100 cm ² , the cooling capacity is small. When the amount of mist sprayed onto the simulated mold 900 is 5000 mg/100 cm ² , water accumulates in the simulated mold 900 and workability decreases. When the amount of mist sprayed onto the aluminum alloy plate is 0 g/100 cm ² (no spraying), the temperature of the aluminum alloy plate increases. When the amount of mist sprayed onto the aluminum alloy plate is 2 g/100 cm ² , the temperature of the aluminum alloy plate becomes sufficiently low. The temperature of the aluminum alloy plate here does not include the temperature rise due to the working heating of the actual press working. Here, it is assumed that the actual temperature rise due to heating during press working is 70°C. Therefore, in order to set the temperature of the aluminum alloy plate to 200° C. or lower during the actual press working, the temperature of the aluminum alloy plate should be 130° C. or lower. When the amount of spray to the mold and the amount of spray to the aluminum alloy plate are (1) 50 mg/100 cm ² and 0 g/100 cm ² (no spray) and (2) 500 mg/100 cm ² and 0 g/100 cm ² (no spray) , the temperature of the aluminum alloy plate exceeds 130°C. In addition, when the spray amount to the mold and the spray amount to the aluminum alloy plate are (4) 5000 mg/100 cm ² and 5 g/100 cm ² , the temperature of the aluminum alloy plate is sufficiently low (130° C. or less), but the mist Excessive amount of spray. That is, water as mist is unnecessarily wasted. Therefore, here, (3) 500 mg/100 cm ² and 2 g/100 cm ² are preferable as the spray amount to the mold and the spray amount to the aluminum alloy plate.

(Action and effect of embodiment)
In the method of hot stamping an aluminum alloy plate according to the present embodiment, the aluminum alloy plate 200 is heated in a heating furnace to reach a temperature of 300° C. or more and less than 580° C. for a holding time of less than 10 minutes. The mold 100 is a steel material mold including steel materials such as tool steel, high-speed steel, and super steel. The mold 100 is cooled by the coolant flowing through the cooling water channel 150 . Also, the mold 100 is cooled by mist spraying. The heated aluminum alloy plate 200 is taken out from the heating furnace, set in the mold 100, and pressed. During press working, the aluminum alloy plate 200 is cooled to 200° C. or less at the bottom dead center of the die 100 . Further, even if the aluminum alloy plate 200 is not cooled to 200° C. or lower at the bottom dead center of the mold 100 during press working, the aluminum alloy plate is sprayed with mist after press working and cooled to 200° C. or lower. Cooled. According to the hot stamping method for the aluminum alloy plate of the present embodiment, the formability of the aluminum alloy can be improved, a shape that has been difficult to form is possible, and the number of mold steps can be reduced. By cooling the mold 100, the temperature of the mold 100 can be reduced to less than 100°C. By cooling the mold 100, the aluminum alloy plate 200 to be processed can be cooled. By spraying mist onto the pressed aluminum alloy plate 200, the aluminum alloy plate can be cooled. In addition to introducing a coolant into the mold 100 and mist spraying, the aluminum alloy plate after pressing is also cooled by mist spraying, so that even if the mold 100 is a steel mold, direct water cooling is not required. , the aluminum alloy plate can be cooled to a predetermined temperature. Also, by cooling the aluminum alloy plate 200 to 200° C. or less, a molded article having excellent shape fixability and flatness can be produced. Direct water cooling of the aluminum alloy plate after press working can be omitted by cooling with a cooling water channel and mist spraying. By not directly cooling with water, it is possible to suppress the decrease in press speed, the complication of the mold shape, and the complication of the working process. Thereby, the productivity and simplicity of the press working process can be improved. The hot stamping method for the aluminum alloy plate of the present embodiment provides various excellent properties depending on the aluminum alloy used, and is applied to, for example, weight reduction of automobile bodies, cooling members necessary for electrification, sensor parts, etc. sell.

In addition, the hot stamping method for 6000 series aluminum alloys achieves strength and formability equal to or higher than those of steel sheets with excellent formability (for example, SPCE). Realize difficult shapes. The hot stamping method for 6000 series aluminum alloys is superior in dimensional accuracy (flatness) compared to the die casting method. In addition, 6000 series aluminum alloy has better thermal conductivity (150 W/m K or more) and corrosion resistance than die-cast products (e.g. ADC12; thermal conductivity 80 W/m K). can be applied to parts that require

Each of the above embodiments can be implemented in combination as much as possible.

100 Mold 110 Upper mold 111 Upper mold die set 112 Upper mold wrinkle holding part 113 Punch 120 Lower mold 121 Lower mold wrinkle holding part 122 Lower mold die set 130 Cooling channel 140 Thermocouple installation hole 150 Cooling channel 151 First part 152 Second Second part 153 Third part 160 Thermocouple installation hole 200 Aluminum alloy plate 310 Thermocouple 320 Thermocouple 900 Simulation mold 930 Cooling channel 931 First part 932 Second part 933 Third part 941 First thermocouple installation hole 942 Second Thermocouple installation hole 960 Thermocouple installation hole

Claims (6)

a heating step of holding the aluminum alloy plate at a temperature of 300° C. or more and less than 580° C. for a time of 10 minutes or less;
and a pressing step of supplying the aluminum alloy plate to a steel mold maintained at a temperature of 120° C. or less and press working, and cooling the aluminum alloy plate to 200° C. or less at the bottom dead center of the press working. Aluminum alloy plate processing method. The steel mold is a mold using at least one of tool steel, high-speed steel, and carbide steel, and includes a cooling water channel for flowing a coolant, and the coolant is supplied to the cooling water channel at an amount of 5 L/min or more. supplied,
The aluminum alloy plate processing method according to claim 1. Before the press working step, a mold spraying step of spraying mist-like water or a water-soluble lubricant to the steel mold in an amount of 10 mg or more per 100 cm ² of the area of the aluminum alloy plate.
The aluminum alloy plate processing method according to claim 1 or 2. An aluminum alloy plate spraying step of spraying the aluminum alloy plate after the pressing step in an amount of 1 g or more per 100 cm ² of the area of the aluminum alloy plate,
The aluminum alloy plate processing method according to any one of claims 1 to 3. The steel mold is plated,
The aluminum alloy plate processing method according to any one of claims 1 to 4. The thickness of the aluminum alloy plate is 1.5 mm or more and less than 5 mm, the holding time at the bottom dead center in the pressing step is less than 10 seconds, and the height of the aluminum alloy plate after the pressing step is 40 mm or less. is
The aluminum alloy plate processing method according to any one of claims 1 to 5.

Images