EP4714567A1

EP4714567A1 - Molding system, molding device, and molding method

Info

Publication number: EP4714567A1
Application number: EP24807100.3A
Authority: EP
Inventors: Ryohei Ikeda; Kimihiro NOGIWA; Masashi Kawakami; Tomoyoshi MAENO; Yuta Sugiyama
Original assignee: Sumitomo Heavy Industries Ltd
Current assignee: Sumitomo Heavy Industries Ltd
Priority date: 2023-05-17
Filing date: 2024-05-08
Publication date: 2026-03-25
Also published as: US20260001117A1; JPWO2024237148A1; CN121358552A; WO2024237148A1; KR20260009798A

Abstract

A forming system that forms a metal material includes a forming device that performs quenching by forming the metal material that is heated, and an aging treatment device that performs aging treatment on a formed product formed by the forming device, in which, in the forming device, the metal material after undergoing solution treatment and then undergoing artificial aging treatment is formed.

Description

Technical Field

The present disclosure relates to a forming system, a forming device, and a forming method.

Background Art

In the related art, a forming device disclosed in PTL 1 is known as a forming device that forms a metal material. The forming device forms a component having a desired shape by pressing the metal material.

Citation List

Patent Literature

[PTL 1] Japanese Unexamined Patent Publication No. 2013-188793

Summary of Invention

Technical Problem

The component formed by the forming device described above is used in order to construct a predetermined structure. For example, in the field of automobiles, weight reduction is being promoted for fuel efficiency improvement and environmental protection. Therefore, quenching to a formed product is performed by performing heating and expansion forming using a material to be solution-treated, such as a heat-treated aluminum alloy, and performing rapid cooling by heat dissipation due to the contact with a die. However, in some cases, even when aging treatment is performed on the formed product after the forming, a desired strength cannot be obtained. Meanwhile, when the formed product after forming is subjected to solution treatment or the like, there is a problem in that the dimensional accuracy is lowered.
Therefore, an object of the present disclosure is to provide a forming system, a forming device, and a forming method that can improve a strength of a formed product while ensuring dimensional accuracy of the formed product.

Solution to Problem

An aspect of the present disclosure relates to a forming system that forms a metal material, the forming system including: a forming device that performs quenching by forming the metal material that is heated; and an aging treatment device that performs aging treatment on a formed product formed by the forming device, in which, in the forming device, the metal material after undergoing solution treatment and then undergoing artificial aging treatment is formed.
In the forming system, the forming device performs the quenching by forming the heated metal material. Thereafter, the aging treatment device performs the aging treatment of the formed product formed by the forming device. In contrast, in the forming device, the metal material after undergoing the solution treatment and then undergoing the artificial aging treatment is formed. Therefore, in the forming device, even in a case in which rapid heating is performed in an aspect having a small amount of input heat, the precipitates of the metal material are in the solid solution state. Therefore, in the subsequent aging treatment device, the precipitates can be finely dispersed in the formed product (for example, see FIG. 8). As a result, the strength of the formed product can be improved. In addition, since it is not necessary to perform the solution treatment for improving the strength after the forming of the forming device, it is possible to suppress a decrease in the dimensional accuracy of the formed product. From the above, the strength of the formed product can be improved while the dimensional accuracy of the formed product is ensured.
In the forming device, the metal material after undergoing T6 treatment may be formed. In this case, the strength of the formed product after the aging treatment can be improved.
The metal material may be an aluminum alloy. The aluminum alloy has a low specific gravity, and thus the weight of the formed product can be reduced.
The forming device may form the metal material that is heated to 400°C or higher. As a result, the precipitates can remain in the solid solution state.
The metal material may be a metal pipe material, and the forming device may form, by expansion, the metal pipe material that is heated. In this case, unlike hot stamping of a plate material, frictional heat between the die and the metal material can be prevented from being generated, and the seizure of the metal material to the die can be prevented from occurring.
Another aspect of the present disclosure relates to a forming device that performs quenching by forming a metal material that is heated, in which the forming device forms a formed product in which precipitates remain in a solid solution state, in a stage after the forming and before aging treatment is performed.
In the forming device, it is possible to form the formed product in which the precipitates remain in the solid solution state, in a stage after the forming and before the aging treatment is performed. Therefore, in the subsequent aging treatment device, the precipitates can be finely dispersed in the formed product (for example, see FIG. 8). As a result, the strength of the formed product can be improved. In addition, since it is not necessary to perform the solution treatment for improving the strength after the forming of the forming device, it is possible to suppress a decrease in the dimensional accuracy of the formed product. From the above, the strength of the formed product can be improved while the dimensional accuracy of the formed product is ensured.
Still another aspect of the present disclosure relates to a forming method of forming a metal material, the forming method including: heating the metal material after undergoing solution treatment and then undergoing artificial aging treatment, forming the metal material, and performing quenching.
With the forming method, the same operations and effects as those of the above-described forming system can be obtained.

Advantageous Effects of Invention

According to the present disclosure, it is possible to provide the forming system, the forming device, and the forming method that can improve the strength of the formed product while ensuring the dimensional accuracy of the formed product.

Brief Description of Drawings

FIG. 1 is a block configuration diagram illustrating a forming system according to an embodiment of the present disclosure.
FIG. 2 is a schematic configuration view illustrating a forming device according to an embodiment of the present disclosure.
FIG. 3A is a schematic side view illustrating a heating and expanding unit, and FIG. 3B is a sectional view illustrating a state in which a nozzle has sealed a metal pipe material.
FIG. 4 is a schematic view illustrating a process image in Comparative Example 1.
FIGS. 5A and 5B are views illustrating a relationship between a material temperature and a strength and a time in Comparative Examples 1 and 2.
FIG. 6 is a view illustrating a relationship between a material temperature and a strength and a time in Comparative Example 3.
FIG. 7 is a view illustrating a relationship between a material temperature and a strength and a time in Comparative Example 4.
FIG. 8 is a view illustrating a relationship between a material temperature and a strength and a time in Example.
FIGS. 9A and 9B are graphs illustrating a relationship between a Vickers hardness and an aging time in Comparative Example 2 and Example.
FIG. 10 is a graph illustrating a relationship between a heating temperature and a hardness when a T6-treated material is rapidly heated and water-cooled, and then undergoes artificial aging and natural aging.
FIG. 11 is a graph illustrating an image of a relationship between a thermal aging time and strength, a precipitate size, and a precipitate density in a precipitation-hardened aluminum alloy.
FIG. 12 is an image view illustrating a process of a change in the precipitate size and the precipitate density in a material in a production process of Comparative Examples 1 and 2.

Description of Embodiments

Hereinafter, a preferred embodiment of a forming device according to the present disclosure will be described with reference to the accompanying drawings. In the drawings, the same portions or equivalent portions will be denoted by the same reference numerals, and the redundant description thereof will be omitted.
FIG. 1 is a block configuration diagram illustrating a forming system 100 according to the present embodiment. The forming system 100 is a system that forms a metal material. In the present embodiment, a metal pipe material of an aluminum alloy is adopted as the metal material. As a result, the metal pipe is formed as a formed product. The metal material is not limited to the aluminum alloy as long as the metal material can undergo solution treatment, and, for example, a nickel alloy may be used.
As illustrated in FIG. 1, the forming system 100 includes a forming device 1 and an aging treatment device 101. The forming device 1 is a device that performs quenching by forming, by expansion, a heated metal material. The forming device 1 forms a metal pipe by a forming method called steel tube air forming (STAF) forming.
The aging treatment device 101 is a device that performs aging treatment on the metal pipe formed by the forming device 1. The aging treatment device 101 is configured by, for example, a furnace that heats the metal pipe immediately after the forming, for a predetermined time. The metal pipe after undergoing the forming is taken out from the forming device 1, and is transported to the aging treatment device 101 by a transport mechanism or the like. The aging treatment device 101 performs, for example, the heating at 100°C to 170°C for 12 to 24 hours.
Hereinafter, an example of the forming device 1 will be described in detail with reference to FIGS. 2 and 3. FIG. 2 is a schematic configuration view of a forming device 1 according to the present embodiment. As illustrated in FIG. 2, the forming device 1 is a device that forms a metal pipe having a hollow shape by blow forming. In the present embodiment, the forming device 1 is installed on a horizontal plane. The forming device 1 includes a forming die 2, a drive mechanism 3, a holding unit 4, a heating unit 5, a fluid supply unit 6, a cooling unit 7, and a control unit 8. In addition, in the present specification, a metal pipe material 40 (metal material) refers to a hollow article before the completion of forming via the forming device 1. The metal pipe material 40 is a steel-type pipe material that can be quenched. Further, in a horizontal direction, a direction in which the metal pipe material 40 extends during the forming may be referred to as a "longitudinal direction", and a direction perpendicular to the longitudinal direction may be referred to as a "width direction".
The forming die 2 is a die that forms a metal pipe from the metal pipe material 40, and includes a lower die 11 and an upper die 12 that face each other in an up-down direction. The lower die 11 and the upper die 12 are configured by blocks made of steel. Each of the lower die 11 and the upper die 12 is provided with a recessed portion in which the metal pipe material 40 is accommodated. In a state in which the lower die 11 and the upper die 12 are in close contact with each other (die closed state), the respective recessed portions form a space having a target shape in which the metal pipe material is to be formed. Therefore, surfaces of the respective recessed portions are forming surfaces of the forming die 2. The lower die 11 is fixed to a base stage 13 via a die holder or the like. The upper die 12 is fixed to a slide of the drive mechanism 3 via a die holder or the like.
The drive mechanism 3 is a mechanism that moves at least one of the lower die 11 and the upper die 12. In FIG. 2, the drive mechanism 3 has a configuration of moving only the upper die 12. The drive mechanism 3 includes a slide 21 that moves the upper die 12 so that the lower die 11 and the upper die 12 are joined together, a pull-back cylinder 22 as an actuator that generates a force for pulling the slide 21 upward, a main cylinder 23 as a drive source that downward-pressurizes the slide 21, and a drive source 24 that applies a driving force to the main cylinder 23.
The holding unit 4 is a mechanism that holds the metal pipe material 40 disposed between the lower die 11 and the upper die 12. The holding unit 4 includes a lower electrode 26 and an upper electrode 27 that hold the metal pipe material 40 on one end side of the forming die 2 in the longitudinal direction, and a lower electrode 26 and an upper electrode 27 that hold the metal pipe material 40 on the other end side of the forming die 2 in the longitudinal direction. The lower electrodes 26 and the upper electrodes 27 on both sides in the longitudinal direction hold the metal pipe material 40 by interposing vicinities of end portions of the metal pipe material 40 from the up-down direction. Upper surfaces of the lower electrodes 26 and lower surfaces of the upper electrodes 27 are formed with groove portions having a shape corresponding to an outer peripheral surface of the metal pipe material 40. Drive mechanisms (not illustrated) are provided in the lower electrodes 26 and the upper electrodes 27 and are movable independently of each other in the up-down direction.
The heating unit 5 heats the metal pipe material 40. The heating unit 5 is a mechanism that heats the metal pipe material 40 by energizing the metal pipe material 40. The heating unit 5 heats the metal pipe material 40 in a state in which the metal pipe material 40 is separated from the lower die 11 and the upper die 12, between the lower die 11 and the upper die 12. The heating unit 5 includes the lower electrodes 26 and the upper electrodes 27 on both sides in the longitudinal direction, and a power supply 28 that causes a current to flow through the metal pipe material 40 via the electrodes 26 and 27. The heating unit may be disposed in a preceding process of the forming device 1 to perform heating externally.
The fluid supply unit 6 is a mechanism that supplies a high-pressure fluid into the metal pipe material 40 held between the lower die 11 and the upper die 12. The fluid supply unit 6 supplies the high-pressure fluid into the metal pipe material 40 that is brought into a high-temperature state by being heated by the heating unit 5, to expand the metal pipe material 40. The fluid supply unit 6 is provided on both end sides of the forming die 2 in the longitudinal direction. The fluid supply unit 6 includes a nozzle 31 that supplies the fluid from an opening portion of an end portion of the metal pipe material 40 to an inside of the metal pipe material 40, a drive mechanism 32 that moves the nozzle 31 forward and backward with respect to the opening portion of the metal pipe material 40, and a supply source 33 that supplies the high-pressure fluid into the metal pipe material 40 via the nozzle 31. The drive mechanism 32 brings the nozzle 31 into close contact with the end portion of the metal pipe material 40 in a state in which the sealing performance is ensured during the fluid supply and exhaust, and causes the nozzle 31 to be separated from the end portion of the metal pipe material 40 in other cases. The fluid supply unit 6 may supply a gas such as high-pressure air and an inert gas, as the fluid. Additionally, the fluid supply unit 6 may include the heating unit 5 together with the holding unit 4 including a mechanism that moves the metal pipe material 40 in the up-down direction as the same device.
Components of the holding unit 4, the heating unit 5, and the fluid supply unit 6 may be configured as a unitized heating and expanding unit 150. FIG. 3A is a schematic side view illustrating the heating and expanding unit 150. FIG. 3B is a sectional view illustrating a state in which a nozzle 31 has sealed a metal pipe material 40.
As illustrated in FIG. 3A, the heating and expanding unit 150 includes the lower electrode 26, the upper electrode 27, an electrode mounting unit 151 in which the electrodes 26 and 27 are mounted, the nozzle 31, the drive mechanism 32, an elevating unit 152, and a unit base 153. The electrode mounting unit 151 includes an elevating frame 154 and electrode frames 156 and 157. The electrode frames 156 and 157 function as a part of a drive mechanism 60 that supports and moves each of the electrodes 26 and 27. The drive mechanism 32 drives the nozzle 31 and moves up and down together with the electrode mounting unit 151. The drive mechanism 32 includes a piston 61 that holds the nozzle 31, and a cylinder 62 that drives the piston. The elevating unit 152 includes an elevating frame base 64 attached to an upper surface of the unit base 153, and an elevating actuator 66 that applies an elevating operation to the elevating frame 154 of the electrode mounting unit 151 by using these elevating frame bases 64. The elevating frame base 64 includes guide portions 64a and 64b that guide the elevating operation of the elevating frame 154 with respect to the unit base 153. The elevating unit 152 functions as a part of the drive mechanism 60 of the holding unit 4. The heating and expanding unit 150 includes a plurality of unit bases 153 of which the upper surfaces have different inclination angles, and is allowed to collectively change and adjust inclination angles of the lower electrode 26, the upper electrode 27, the nozzle 31, the electrode mounting unit 151, the drive mechanism 32, and the elevating unit 152 by replacing the unit bases 153.
The nozzle 31 is a cylindrical member into which the end portion of the metal pipe material 40 can be inserted. The nozzle 31 is supported by the drive mechanism 32 so that a center line of the nozzle 31 coincides with a reference line SL1. An inner diameter of a feed port 31a at an end portion of the nozzle 31 on the metal pipe material 40 side substantially coincides with an outer diameter of the metal pipe material 40 after expansion forming. In this state, the nozzle 31 supplies the high-pressure fluid from an internal flow path 63 to the metal pipe material 40. Examples of the high-pressure fluid include a gas.
Returning to FIG. 2, the cooling unit 7 is a mechanism that cools the forming die 2. The cooling unit 7 can rapidly cool the metal pipe material 40 by cooling the forming die 2 when the expanded metal pipe material 40 comes into contact with the forming surface of the forming die 2. The cooling unit 7 includes flow paths 36 formed inside the lower die 11 and the upper die 12 and a water circulation mechanism 37 that supplies a cooling water and causes the cooling water to circulate through the flow paths 36.
The control unit 8 is a device that controls the entire forming device 1. The control unit 8 controls the drive mechanism 3, the holding unit 4, the heating unit 5, the fluid supply unit 6, and the cooling unit 7. The control unit 8 repeatedly performs the operation of forming the metal pipe material 40 using the forming die 2.
Specifically, the control unit 8 controls, for example, a transport timing from a transport device, such as a robot arm, to dispose the metal pipe material 40 between the lower die 11 and the upper die 12 in an open state. Alternatively, a worker may manually dispose the metal pipe material 40 between the lower die 11 and the upper die 12. Additionally, the control unit 8 controls an actuator of the holding unit 4 and the like so that the metal pipe material 40 is supported by the lower electrodes 26 on both sides in the longitudinal direction, and then the upper electrodes 27 are lowered to interpose the metal pipe material 40. In addition, the control unit 8 controls the heating unit 5 to perform energization heating on the metal pipe material 40. As a result, an axial current flows through the metal pipe material 40, and an electric resistance of the metal pipe material 40 itself causes the metal pipe material 40 itself to generate heat due to Joule heat.
The control unit 8 closes the forming die 2 by controlling the drive mechanism 3 to lower the upper die 12 and bring the upper die 12 close to the lower die 11. Meanwhile, the control unit 8 controls the fluid supply unit 6 to seal the opening portions of both ends of the metal pipe material 40 with the nozzle 31 and supply the fluid. As a result, the metal pipe material 40, which is softened by the heating, expands and comes into contact with the forming surface of the forming die 2. Then, the metal pipe material 40 is formed to follow the shape of the forming surface of the forming die 2. In addition, in a case in which a metal pipe with a flange is formed, a part of the metal pipe material 40 is made to enter a gap between the lower die 11 and the upper die 12, and then die closing is further performed to crush the entering part to form a flange portion. When the metal pipe material 40 comes into contact with the forming surface, the metal pipe material 40 is quenched by being rapidly cooled by the forming die 2 cooled by the cooling unit 7.
Hereinafter, the features of the forming system 100 and the forming device 1 according to the present embodiment will be described in detail. First, as Comparative Example 1 for the forming system 100 according to the present embodiment, a general hot forming process (for example, hot stamping) using a precipitation-hardened aluminum alloy plate material will be described. FIG. 4 is a schematic view illustrating a process image in Comparative Example 1. As illustrated in FIG. 4, in Comparative Example 1, a heating furnace 202 heats a plate material 210 to about 500°C. The plate material 210 is a material in a state in which the solution treatment or the like is not performed in advance, such as a casting material or an extrusion material. Next, a forming device 200 forms the plate material 210 into a formed product 211. In such a case, the formed product 211 is quenched by the rapid cooling. The treatment of the heating furnace 202 and the forming device 200 corresponds to the solution treatment. Next, the aging treatment device 201 performs the artificial aging treatment on the formed product 211.
FIG. 5A illustrates a graph GA1 illustrating a relationship between a material temperature and a time and a graph GA2 illustrating a relationship between a strength of the material and a time, in Comparative Example 1. As illustrated in FIG. 5A, in Comparative Example 1, the plate material 210 is held after being heated to a temperature equivalent to the solution treatment by furnace heating, and then the quenching and the forming are performed by the die in the forming device 200. In addition, in Comparative Example 1, a desired strength is obtained by performing artificial aging treatment (10 to 24 hours), which is referred to as T6 treatment, with the aging treatment device 201. In the drawing, "PA1" is a location at which the holding is performed at the solution treatment temperature for several minutes. "PA2" is a location at which the hot pressing is performed. "PA3" is a location at which the die quenching is performed. "PA4" is a location at which the artificial aging treatment is performed.
Next, as Comparative Example 2, an example will be described in which STAF forming (forming using the forming device illustrated in FIGS. 2 and 3) is performed using the metal pipe material in a state in which the solution treatment or the like is not performed in advance, such as the casting material or the extrusion material. FIG. 5B illustrates a graph GB1 illustrating a relationship between a material temperature and a time and a graph GB2 illustrating a relationship between a strength of the material and a time, in Comparative Example 2. In the drawing, "PB1" is a location at which the energization heating is performed. "PB2" is a location at which the expansion forming is performed. "PB3" is a location at which the artificial aging treatment is performed.
As illustrated in FIG. 5B, in the forming process of the STAF forming, the heating method is the energization heating, and thus there is no rapid temperature rise and no holding process at the time of reaching the heating temperature. Therefore, as illustrated by "A" in the drawing, a sufficient solution treatment time is not ensured. Therefore, as illustrated in the graph GB2, even after the artificial aging treatment, a desired strength equivalent to the T6 treatment is not obtained. In contrast, in the STAF forming process, a desired strength can be obtained by performing the energization heating, the forming, and the T6 treatment. In the T6 treatment, the artificial aging treatment is performed after the solution treatment of the metal pipe material. However, in a case in which such a process is adopted, since the deformation occurs due to a cooling rate difference between the parts of the component caused by the rapid cooling during the solution treatment, there is a problem in that the dimensional accuracy cannot be ensured.
Next, as Comparative Example 3, the hot stamping using a plate material after undergoing the T6 treatment will be described. In Comparative Example 3, the plate material is heated in the heating furnace. Then, the forming device forms the plate material. The heating furnace and the forming device illustrated in FIG. 4 may be used. FIG. 6 illustrates a graph GF1 illustrating a relationship between a material temperature and a time and a graph GF2 illustrating a relationship between a strength of the material and a time, in Comparative Example 3. As illustrated in FIG. 6, in Comparative Example 3, the plate material is heated to 200°C to 300°C by the furnace heating, and then the quenching and the forming are performed by the die in the forming device. In the drawing, "PF1" is a location at which the heating is performed. "PF2" is a location at which the hot pressing is performed. "PF3" is a location at which the die quenching is performed. In Comparative Example 3, since the heating temperature is low, there is a problem in that the deformation resistance during the forming is high, or the forming shape is restricted.
Next, as Comparative Example 4, the hot stamping using a solution-treated material plate will be described. The plate material has not undergone the artificial aging treatment after the solution treatment. In Comparative Example 4, the plate material is heated in the heating furnace. Then, the forming device forms the plate material. Next, a desired strength is obtained by performing the artificial aging treatment (10 to 24 hours), which is referred to as the T6 treatment, with the aging treatment device. The heating furnace, the forming device, and the aging treatment device illustrated in FIG. 4 may be used. FIG. 7 illustrates a graph GH1 illustrating a relationship between a material temperature and a time and a graph GH2 illustrating a relationship between a strength of the material and a time, in Comparative Example 4. As illustrated in FIG. 7, in Comparative Example 4, the plate material is heated to 350°C to 450°C by the furnace heating, and then the quenching and the forming are performed by the die in the forming device, and the artificial aging treatment is performed. In the drawing, "PH1" is a location at which the heating is performed. "PH2" is a location at which the hot pressing is performed. "PH3" is a location at which the die quenching is performed. "PH4" is a location at which the artificial aging treatment is performed.
In Comparative Example 4, since the material after the solution treatment is used, the material is in a supersaturated state (that is, the material is in a thermally unstable state), so that the natural aging progresses before the press forming, depending on the storage conditions (time, temperature, and the like) of the material. As a result, there is a problem in that the strength varies after the press working and the artificial aging (see virtual line GH2x). In addition, in Comparative Example 4, when the heating temperature is set to a high temperature of 500°C or higher, the seizure to the die occurs due to the frictional heat between the die and the material during the processing.
In order to solve the above-described problems of Comparative Example, the forming system 100 according to the present embodiment forms, in the forming device 1, the metal pipe material 40 after undergoing the solution treatment and then the artificial aging treatment. In the forming device 1, the metal pipe material 40 after undergoing the T6 treatment is formed. By the energization heating, the forming, and the artificial aging treatment using the metal pipe material 40 after undergoing the T6 treatment, it is possible to obtain the strength equivalent to the T6-treated material as the formed product of the forming system 100.
FIG. 8 illustrates a graph GK1 illustrating a relationship between a material temperature and a time and a graph GK2 illustrating a relationship between a strength of the material and a time, in the forming system 100 according to the embodiment. In the drawing, "PK1" is a location at which the energization heating is performed. Here, the heating is performed by setting the heating temperature to 400°C to 610°C. Here, 610°C is a temperature equal to or lower than a melting temperature. "PK2" is a location at which the expansion forming is performed. "PK3" is a location at which the artificial aging treatment is performed.
FIG. 9A illustrates aging characteristics in a case in which, as in Comparative Example 2, the material (as-cast or as-extruded material) that has not undergone the T6 treatment is used as the forming material. FIG. 9B illustrates the aging characteristics when, as the forming material, an A6063-T6-treated material (Example) is rapidly heated to the heating temperature of 520°C and then water-cooled, and then undergoes the artificial aging and the natural aging. FIG. 9A illustrates a graph GC1 illustrating characteristics of the natural aging and a graph GC2 illustrating characteristics of the artificial aging. In addition, FIG. 9A illustrates a reference line ST1 indicating a hardness after annealing (27.0 HV) and a reference line ST2 indicating a T6-treated material hardness (82.4 HV). FIG. 9B illustrates a graph GD1 illustrating characteristics of the natural aging and a graph GD2 illustrating characteristics of the artificial aging. In addition, FIG. 9B illustrates a reference line ST2 indicating a T6-treated material hardness (82.4 HV).
As illustrated in FIG. 9A, the material that has not undergone the T6 treatment has a slight increase in hardness even when the artificial aging treatment is performed. In contrast, as illustrated in FIG. 9B, the material that has undergone the T6 treatment has an increased hardness with the artificial aging time, and has the same hardness as the T6-treated material in about 12 hours. That is, it can be said that the solution treatment is also performed during the rapid heating.
FIG. 10 is a graph illustrating a relationship between a heating temperature and a hardness when the A6063-T6-treated material is rapidly heated to a heating temperature of 200°C to 520°C and then water-cooled, and then undergoes the artificial aging and the natural aging. FIG. 10 illustrates a graph GL illustrating a relationship between a heating temperature and a hardness after the water cooling. At the heating temperature of 400°C, the hardness equivalent to the T6-treated material can be obtained in 16 hours of the artificial aging, and at the heating temperature of 520°C, the hardness equivalent to the T6-treated material can be obtained in 12 hours of the artificial aging. The hardness obtained by the artificial aging is greater than the hardness obtained by the natural aging for 7 days.
FIG. 11 is a graph illustrating an image of a relationship between a thermal aging time and a strength (graph GE1), a precipitate size (graph GE2), and a precipitate density (graph GE3) of the precipitation-hardened aluminum alloy. On an upper side of the graph of FIG. 11, an image is illustrated in which the precipitates in the material are precipitated as the thermal aging time elapses. In an initial stage, the atoms constituting the precipitates are completely in a solid solution state (state 1). When the thermal aging time progresses, a state is reached in which the atoms constituting the precipitates are gradually precipitated (state 2). When the thermal aging time further progresses, a state is reached in which the atoms constituting the precipitates are completely precipitated (state 3). A number density and the precipitate size of the precipitates are also increased. The aging time progresses, and after exceeding the peak of the strength, a state is reached in which the precipitate size becomes coarse with respect to the state 3 (state 4). When the thermal aging time further progresses, a state is reached in which the precipitates are combined with each other while the size increases (state 5). The number density after exceeding the peak decreases (Ostwald ripening). In this way, the strength of the material can be increased by reaching "state 3".
FIG. 12 is an image view illustrating a process of a change in the precipitate size and the precipitate density in the material in the production process of Comparative Examples 1 and 2. In addition, in FIGS. 6 to 8 and 12, the state of the precipitates in the material in the processing process is associated with the state 1 to the state 5 described in FIG. 11 for each Comparative Example or Example.
In Comparative Example 1, the material state is a solution-and-artificial-item-treated material, and thus the precipitates are finely dispersed (state 3). When the heating is performed, the precipitates form the solid solution due to sufficient input heat during the heating process using the furnace heating (state 0). After the forming and the rapid cooling, the solid solution state is maintained without the precipitation of the precipitates due to the rapid cooling (state 1). Finally, the precipitates are finely dispersed by the artificial aging (state 3). In a case in which the material after undergoing the T6 treatment is used as the material in the hot stamping, the material exhibits the same structure as above after the heating process.
In Comparative Example 2, in the material state, the precipitates are large (state 5), and the energization heating in the STAF forming does not include a rapid temperature increase or temperature holding process. That is, since the input heat to the material is small, the precipitates do not form the solid solution (state 5). Therefore, the structure is not changed even after the forming and the rapid cooling and the artificial aging process (state 5).
As illustrated in FIG. 6, in Comparative Example 3, the precipitates are finely dispersed in the material (T6-treated material plate) (state 3). In the heating process, the precipitate size increases (state 4), and then the processing strain is applied in the subsequent forming process, but the strength is lower than the strength of the T6-treated material due to the thermal energy applied during the heating.
As illustrated in FIG. 7, in Comparative Example 4, the precipitates form the solid solution in the material (solution-treated material plate) (state 1). In the heating process, the heating is performed to the temperature of 350°C to 450°C, and then the cooling using the mold is immediately performed, so that the generation of the precipitates is suppressed (state 2). Then, the artificial aging treatment is performed, so that the strength equivalent to the T6 treatment can be obtained (state 3).
As illustrated in FIG. 8, in the example, the material after undergoing the T6 treatment is used, so that the precipitates are finely dispersed in the material state (state 3). By performing the heating to the temperature of 400°C to 610°C in the heating process, the precipitates form the solid solution (state 1). After the forming and the rapid cooling, the solid solution state is maintained without the precipitation of the precipitates due to the rapid cooling (state 1). Finally, the precipitates are finely dispersed by the artificial aging (state 3). As a result, it is possible to obtain the strength equivalent to the T6 treatment.
In the process illustrated in FIG. 8, a state immediately after the forming by the forming device 1 corresponds to a state of "state 1" illustrated in "after the forming and the rapid cooling". Thereafter, the artificial aging is performed by the aging treatment device 101, and a state of "after artificial aging" is reached. As illustrated in FIG. 8, the forming device 1 according to the present embodiment forms the formed product in which the precipitates remain in the solid solution state in a stage after the forming and before the aging treatment is performed.
Hereinafter, the operations and effects of the forming system 100, the forming device 1, and the forming method according to the present embodiment will be described.
In the forming system 100, the forming device 1 performs the quenching by performing expansion forming of the heated metal material. Thereafter, the aging treatment device 101 performs the aging treatment on the formed product formed by the forming device 1. In contrast, in the forming device 1, the metal material after undergoing the solution treatment and then undergoing the artificial aging treatment is formed. Therefore, in the forming device 1, even in a case in which the rapid heating is performed in an aspect having a small amount of input heat, the precipitates of the metal material are in the solid solution state. Therefore, in the subsequent aging treatment device 101, the precipitates can be finely dispersed in the formed product (for example, see "Example" in FIG. 8). As a result, the strength of the formed product can be improved. In addition, since it is not necessary to perform the solution treatment for improving the strength after the forming of the forming device 1, it is possible to suppress the decrease in the dimensional accuracy of the formed product. From the above, the strength of the formed product can be improved while the dimensional accuracy of the formed product is ensured.
In the forming device 1, the metal material after undergoing the T6 treatment may be formed. In this case, the strength of the formed product after the aging treatment can be improved. In addition, since the metal material after undergoing the T6 treatment is in a thermally stable state, the material quality variation in the storage conditions can be reduced.
The metal material may be an aluminum alloy. The aluminum alloy has a low specific gravity, and thus the weight of the formed product can be reduced.
The forming device 1 may form the metal material that is heated to 400°C or higher. As a result, the precipitates can remain in the solid solution state.
The metal material may be a metal pipe material, and the forming device 1 may form, by expansion, the metal pipe material that is heated. In this case, unlike hot stamping of a plate material, frictional heat between the die and the metal material can be prevented from being generated, and the seizure of the metal material to the die can be prevented from occurring. For example, as illustrated in the forming device 200 for the hot stamping in FIG. 4, the die is pressed against the plate material to cause deformation, so that the frictional heat between the die and the metal material increases at corner portions or the like. In contrast, in the expansion forming, the metal pipe material that is expanded and widened is formed by being received by the die, so that less frictional heat is generated compared to the hot stamping.
Another aspect of the present embodiment relates to the forming device 1 that performs the quenching by forming the metal material that is heated, in which the forming device 1 forms the formed product in which the precipitates remain in the solid solution state, in a stage after the forming and before the aging treatment is performed.
In the forming device 1, it is possible to form the formed product in which the precipitates remain in the solid solution state, in a stage after the forming and before the aging treatment is performed. Therefore, in the subsequent aging treatment device 101, the precipitates can be finely dispersed in the formed product (for example, see FIG. 8). As a result, the strength of the formed product can be improved. In addition, since it is not necessary to perform the solution treatment for improving the strength after the forming of the forming device 1, it is possible to suppress the decrease in the dimensional accuracy of the formed product. From the above, the strength of the formed product can be improved while the dimensional accuracy of the formed product is ensured.
Still another aspect of the present embodiment relates to the forming method of forming the metal material, the forming method including: heating the metal material after undergoing the solution treatment and then undergoing the artificial aging treatment, forming the metal material, and performing the quenching.
With the forming method, the same operations and effects as those of the forming system 100 can be obtained.
The present disclosure is not limited to the above-described embodiment.
For example, in the above-described embodiment, the metal pipe material 40 after undergoing the T6 treatment is adopted as the metal pipe material 40 to be formed by the forming device 1. However, the treatment applied to the metal pipe material 40 before the forming is not limited to the T6 as long as the solution treatment is performed and then the artificial aging treatment is performed. For example, the metal pipe material 40 that has undergone the solution treatment, the cold working, and then the artificial aging hardening treatment may be used.
The configuration of the forming device 1 is not particularly limited, and may be changed from the structures illustrated in FIGS. 2 and 3. For example, a forming device that performs the hot stamping on the metal material that has undergone the artificial aging treatment by performing the solution treatment may be used. The aging treatment is performed in the aging treatment device after the forming.

Reference Signs List

1: Forming device
40: Metal pipe material (metal material)
100: Forming system
101: Aging treatment device

Claims

A forming system that forms a metal material, the forming system comprising:
a forming device that performs quenching by forming the metal material that is heated; and

an aging treatment device that performs aging treatment on a formed product formed by the forming device,

wherein, in the forming device, the metal material after undergoing solution treatment and then undergoing artificial aging treatment is formed.
The forming system according to claim 1,
wherein, in the forming device, the metal material after undergoing T6 treatment is formed.
The forming system according to claim 1,
wherein the metal material is an aluminum alloy.
The forming system according to claim 1,
wherein the forming device forms the metal material that is heated to 400°C or higher.
The forming system according to claim 1,
wherein the metal material is a metal pipe material, and

the forming device forms, by expansion, the metal pipe material that is heated.
A forming device that performs quenching by forming a metal material that is heated,
wherein the forming device forms a formed product in which precipitates remain in a solid solution state, in a stage after the forming and before aging treatment is performed.
A forming method of forming a metal material, the forming method comprising:
heating the metal material after undergoing solution treatment and then undergoing artificial aging treatment, forming the metal material, and performing quenching.