EP4609963A1

EP4609963A1 - Molding device and metal member

Info

Publication number: EP4609963A1
Application number: EP23882205.0A
Authority: EP
Inventors: Kimihiro Nogiwa; Masashi Kawakami; Ryohei Ikeda
Original assignee: Sumitomo Heavy Industries Ltd
Current assignee: Sumitomo Heavy Industries Ltd
Priority date: 2022-10-28
Filing date: 2023-08-23
Publication date: 2025-09-03
Also published as: WO2024089989A1; CN119730973A; JPWO2024089989A1; US20250205767A1; EP4609963A4; KR20250103608A

Abstract

A forming device forms a metal material made of an aluminum alloy, in which the forming device controls a cooling rate of the aluminum alloy during a solution treatment, to provide a difference in strength of the aluminum alloy after an aging treatment.

Description

Technical Field

The present disclosure relates to a forming device and a metal member.

Background Art

In the related art, a forming device that forms a heated metal material has been known. For example, PTL 1 discloses a forming device including a die including a pair of a lower die and an upper die, a gas supply unit that supplies a gas into a metal pipe material held between the dies, and a heating unit that heats the metal pipe material by electrical heating. Such a forming device includes a cooling unit that causes water to flow through a flow path formed in the die in order to cool the heated metal pipe during the forming. Therefore, the forming device can perform quenching forming by bringing the cooled die into contact with the metal pipe material.

Citation List

Patent Literature

[PTL 1] Japanese Unexamined Patent Publication No. 2009-220141

Summary of Invention

Technical Problem

Here, in some cases, an aluminum alloy is used as a metal material from the viewpoint of weight saving. In the forming of the aluminum alloy, an aging treatment using heat is performed after a solution treatment accompanying the forming. Although a metal member made of a high-strength aluminum alloy is obtained by this process, it has been required to further provide a difference in strength in the metal member.
Therefore, the present disclosure has an object to provide a forming device that can provide a difference in strength in a metal member made of an aluminum alloy after forming, and a metal member.

Solution to Problem

An aspect of the present disclosure relates to a forming device that forms a metal material made of an aluminum alloy, in which the forming device controls a cooling rate of the aluminum alloy during a solution treatment, to provide a difference in strength of the aluminum alloy after an aging treatment.
In the forming device, the forming device forms the metal material made of the aluminum alloy. For such an aluminum alloy, the aging treatment using heat is performed after the solution treatment via the forming device. The forming device controls the cooling rate of the aluminum alloy during the solution treatment. In the aluminum alloy, the strength obtained after the aging treatment is changed depending on the cooling rate of the solution treatment. Therefore, the forming device can provide, in the aluminum alloy, a portion in which the cooling rate is high and a portion in which the cooling rate is low. In this way, when the portions having the different cooling rates are provided in the aluminum alloy, the portions having the different strengths can be obtained after the aging treatment. From the above, the difference in strength can be provided in the metal member made of the aluminum alloy after the forming.
Controlling the cooling rate may be performed by partially heating a die. In this case, when the heated portion of the die and the aluminum alloy come into contact with each other, the cooling rate of the portion is lowered. As a result, the cooling rate can be easily controlled.
A metal member after the forming may include a first portion having a high number density of precipitates of alloying elements, and a second portion having a lower number density of the precipitates of the alloying elements than the first portion. The first portion has a high number density of the precipitates and high strength. The second portion has a low number density of the precipitates and low strength. In this way, the difference in strength can be provided between the first portion and the second portion.
A heating holding time may be provided during heating of the solution treatment. In this case, in the solution treatment, the time for melting the aluminum can be secured. As a result, it is easy to provide the difference in strength by controlling the cooling rate.
A metal member includes a first portion having a high number density of precipitates of alloying elements, and a second portion having a lower number density of the precipitates of the alloying elements than the first portion.
In the metal member, the first portion has a high number density of the precipitates and high strength. The second portion has a low number density of the precipitates and low strength. In this way, the difference in strength can be provided between the first portion and the second portion.

Advantageous Effects of Invention

According to the present disclosure, it is possible to provide the forming device that can provide the difference in strength in the metal member made of the aluminum alloy after the forming, and the metal member.

Brief Description of Drawings

Fig. 1 is a schematic configuration view illustrating a forming device according to an embodiment of the present disclosure.
Fig. 2A is a schematic side view illustrating a heating and expanding unit. Fig. 2B is a sectional view illustrating a state where a nozzle has sealed a metal pipe material.
Fig. 3 is a schematic sectional view illustrating a temperature control mechanism of a forming die.
Fig. 4 is a schematic view illustrating a metal pipe after forming.
Fig. 5 is a view illustrating a state of aluminum.
Figs. 6A to 6C illustrate images of an atomic arrangement in a precipitation state.
Fig. 7A is a graph illustrating a transition of a temperature of an aluminum alloy during a solution treatment and an aging treatment, and Fig. 7B is a graph illustrating various characteristics of the aluminum alloy.
Fig. 8 illustrates a precipitation state at each time illustrated in Fig. 7A.
Fig. 9 is a graph illustrating a transition of the temperature of the aluminum alloy during the solution treatment and during the aging treatment.
Fig. 10 is a view illustrating a precipitation state at each time of a high strength region subjected to rapid cooling and a low strength region subjected to controlled cooling.

Description of Embodiments

Hereinafter, a preferred embodiment of a forming device according to the present disclosure will be described with reference to the drawings. In the drawings, the same reference numerals will be given to the same portions or equivalent portions, and the redundant description thereof will be omitted.
Fig. 1 is a schematic configuration view of a forming device 1 according to the present embodiment. As illustrated in Fig. 1, 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 temperature control unit 7, and a control unit 8. 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. In addition, 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 140 (see Fig. 4) 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 part in which the metal pipe material 40 is accommodated. In a state where the lower die 11 and the upper die 12 are in close contact with each other (die closed state), the respective recessed parts form a space having a target shape in which the metal pipe material is to be formed. Therefore, surfaces of the respective recessed parts 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.
Here, in the present embodiment, the metal pipe material 40 is a metal material made of an aluminum alloy. The metal pipe material 40 includes a high strength region E1 in which the strength is high and a low strength region E2 in which the strength is low. Therefore, the forming die 2 performs rapid cooling in which the cooling rate is increased in the high strength region E1 of the metal pipe material 40, and performs controlled cooling in which the cooling rate is lowered in the low strength region E2 of the metal pipe material 40. The upper die 12 and the lower die 11 include rapid cooling portions 12A and 11A for performing quenching to the high strength region E1 and controlled cooling portions 12B and 11B for preventing the low strength region E2 from being quenched. In the present embodiment, the low strength region E2 is provided at a substantially central position of the metal pipe 140 (metal pipe material 40), and the high strength regions E1 are provided to interpose the low strength region E2 in the longitudinal direction. Therefore, the upper die 12 and the lower die 11 include the controlled cooling portions 12B and 11B at the central position and the rapid cooling portions 12A and 11A that interpose the low strength region E2 in the longitudinal direction. As a result, as illustrated in Fig. 4, the low strength region E2 (hatched portion) of the metal pipe 140 after the forming is a portion partially having low strength, and the high strength region E1 is a portion having high strength.
The drive mechanism 3 is a mechanism that moves at least one of the lower die 11 and the upper die 12. In Fig. 1, 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 such 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 in the longitudinal direction of the forming die 2, and a lower electrode 26 and an upper electrode 27 that hold the metal pipe material 40 on the other end side in the longitudinal direction of the forming die 2. 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 where the metal pipe material 40 is spaced apart 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 has been brought into a high-temperature state by being heated by the heating unit 5, to expand the metal pipe material 40. The fluid supply units 6 are 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 sealing performance is secured during the fluid supply and exhaust, and causes the nozzle 31 to be spaced apart 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. 2A is a schematic side view illustrating the heating and expanding unit 150. Fig. 2B is a sectional view illustrating a state where the nozzle 31 has sealed the metal pipe material 40.
As illustrated in Fig. 2A, 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 the 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 such 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. 1, the temperature control unit 7 is a mechanism that controls a temperature of the forming die 2. The temperature control unit 7 controls the temperature of the forming die 2 to reduce the warpage in the low strength region E2. The temperature control unit 7 can rapidly cool the metal pipe material 40 to perform quenching when the expanded metal pipe material 40 comes into contact with the forming surface of the forming die 2, by cooling the forming die 2 in the rapid cooling portions 12A and 11A. In addition, the temperature control unit 7 can control the temperature of the metal pipe material 40 to a temperature at which the quenching does not occur when the expanded metal pipe material 40 comes into contact with the forming surface of the forming die 2, by performing the temperature control of the forming die 2 in the controlled cooling portions 12B and 11B. The temperature control unit 7 includes flow paths formed inside the lower die 11 and the upper die 12, a supply mechanism 37 that supplies a temperature control medium and causes the temperature control medium to circulate through the flow paths, and a control unit 8 that controls the supply mechanism 37.
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 supply mechanism 37. 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 such 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 electrically heat the metal pipe material 40. Therefore, 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 controls the drive mechanism 3 to lower the upper die 12 and bring the upper die 12 close to the lower die 11, thereby closing the forming die 2. 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. Therefore, the metal pipe material 40 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 a shape of the forming surface of the forming die 2. In addition, in a case where 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 high strength region E1 of the metal pipe material 40 comes into contact with the forming surface, the metal pipe material 40 is rapidly cooled by being rapidly cooled by using the forming die 2 cooled by the temperature control unit 7.
The forming device 1 controls the cooling rate of the aluminum alloy during the solution treatment, to provide the difference in strength of the aluminum alloy after the aging treatment. The solution treatment is a treatment of forming the heated metal pipe material 40 by using the dies 11 and 12. The aging treatment is a treatment of performing artificial aging (painting firing) after the forming of the metal pipe 140 via the forming device 1. The forming device 1 brings the rapid cooling portions 11A and 12A into contact with each other to increase the cooling rate of the high strength region E1 of the metal pipe material 40 made of the aluminum alloy and perform the rapid cooling. The forming device 1 brings the controlled cooling portions 11B and 12B into contact with each other to lower the cooling rate of the low strength region E2 of the metal pipe material 40 made of the aluminum alloy and perform the controlled cooling on the low strength region E2 of the metal pipe material 40. As a result, the forming device 1 provides the difference in strength in the metal pipe 140 made of the aluminum alloy after the aging treatment. The high strength region E1 after the aging treatment has lower strength than the low strength region E2. Controlling the cooling rate is performed by partially heating the dies 11 and 12. Specifically, the controlled cooling portions 11B and 12B of the dies 11 and 12 are partially heated.
The temperature control unit 7 will be described in more detail with reference to Fig. 3. The temperature control unit 7 includes temperature control mechanisms 70 and 80 that control the temperature of the forming die 2. The temperature control mechanism 70 is provided inside the upper die 12, and controls the temperature of the forming surface of the die 12. The temperature control mechanism 80 is provided inside the lower die 11, and controls the temperature of the forming surface of the die 11. The temperature control mechanism 70 has flow paths 71 provided in the rapid cooling portions 12A on both sides of the die 12. The flow path 71 cools the forming surface of the rapid cooling portion 12A by causing the cooling water from the supply mechanism 37 to flow. In addition, the temperature control mechanism 80 has flow paths 81 provided in the rapid cooling portions 11A on both sides of the die 11. The flow path 81 cools the forming surface of the rapid cooling portion 11A by causing the cooling water from the supply mechanism 37 to flow.
Here, the controlled cooling portions 12B and 11B include heating die blocks 12Ba and 11Ba on the forming surface side, and normal die blocks 12Bb and 11Bb on the opposite side. The normal die blocks 12Bb and 11Bb are blocks that connect the rapid cooling portions 12A and 11A on both sides to each other. The temperature control mechanisms 70 and 80 include flow paths 72 and 82 provided in the normal die blocks 12Bb and 11Bb. The same cooling water as that in the flow paths 71 and 81 of the rapid cooling portions 12A and 11A is supplied to the flow paths 72 and 82. The heating die blocks 12Ba and 11Ba are blocks having a higher temperature than the rapid cooling portions 12A and 11A. A heat insulating member 75 (or a gap) is provided between the rapid cooling portions 12A and 11A and the heating die blocks 12Ba and 11Ba. The temperature control mechanisms 70 and 80 include flow paths 73 and 83 provided inside the heating die blocks 12Ba and 11Ba. The flow paths 73 and 83 cause a fluid having a higher temperature than the fluid in the flow paths 71 and 81 to flow, and thus the temperature of the forming surface of the controlled cooling portions 12B and 11B is higher than the temperature of the forming surface of the rapid cooling portions 12A and 11A. The temperature control mechanisms 70 and 80 may include a heater and the like instead of the flow paths 73 and 83. In this manner, the temperature control mechanisms 70 and 80 can control the cooling rate of the aluminum alloy during the solution treatment (during the forming) by partially heating the controlled cooling portions 11B and 12B.
Next, the reason why the strength of the aluminum alloy is different will be described with reference to Figs. 5 to 10, and the control of the cooling rate of the aluminum alloy for such a purpose will be described. First, the precipitation of the alloying element in the aluminum will be described with reference to Figs. 5 and 6. Fig. 5 is a view illustrating a state of the alloying element in the aluminum. A graph illustrated in Fig. 5 illustrates a relationship between a concentration ratio of aluminum and the alloying element in the aluminum alloy and the temperature. In addition, a conceptual view illustrated on the right side of the graph illustrates a state of a metal structure of the aluminum alloy in each state. In the graph, "1" indicates a state when the solution treatment of the aluminum alloy (metal pipe 140) is performed. In "1", the aluminum alloy is in a "solid solution state", and the alloying element is in a completely solid-solved state. "2" indicates a state when the aluminum alloy is quenched. In "2", the aluminum alloy is in the "supersaturated solid solution state", and the precipitate phase is originally more stable. However, the aluminum alloy is rapidly cooled in a solid-solubilized state, so that the alloying element is in a solid-solubilized state. "3" indicates a state when the aging treatment of the aluminum alloy is performed at a relatively low temperature after the quenching. In Fig. 3, the aluminum alloy is in a state where a "metastable precipitate phase" is precipitated. "4" indicates a state when the aging treatment of the aluminum alloy is performed at a relatively high temperature after the quenching. In "4", the aluminum alloy is in a state where the "stable precipitate phase" is precipitated. "5" indicates a state when the aluminum alloy is subjected to the controlled cooling. In "5", the "stable precipitate phase" is precipitated during the cooling via the controlled cooling. In this case, the precipitation occurs not only inside the crystal grains but also at the crystal grain boundaries. In order to strengthen the aluminum alloy, it is effective that the precipitates are densely precipitated inside the crystal grain. The precipitates are more densely precipitated inside the crystal grains in the state of "4" than in the state of "5".
Figs. 6A to 6C illustrate images of an atomic arrangement in the precipitation state. Fig. 6A illustrates an image of the atomic arrangement in the solid solution. Fig. 6B illustrates an image of the atomic arrangement in the intermediate phase. Fig. 6C illustrates an image of the atomic arrangement in the stable precipitate phase (parallel phase).
Next, the treatment time of the aging treatment will be described with reference to Figs. 7A to 8. Fig. 7A is a graph illustrating a transition of the temperature of the aluminum alloy during the solution treatment and during the aging treatment. As illustrated in Fig. 7A, a time t1 is a time immediately before the aging treatment is started. A time t2 is a time during the aging treatment. A time t3 is a heating end time of the aging treatment when the aging treatment time is appropriately set. A time t4 is a heating end time of the aging treatment heating when the aging treatment time is inappropriately set.
A graph G1 in Fig. 7B is a graph illustrating the size of the precipitates of the alloying elements in the aluminum alloy. A graph G2 is a graph illustrating the strength of the aluminum alloy. A graph G3 is a graph illustrating the number density of the precipitates of the alloying elements in the aluminum alloy. As illustrated in the graph G1, the size of the precipitate increases with time. On the other hand, as illustrated in the graph G2, the strength of the aluminum alloy reaches a strength peak at the time t3 and then decreases. As illustrated in the graph G3, the number density of the precipitates reaches a peak earlier than the time t3, and then decreases. Fig. 8 illustrates the precipitation state at each of the times t1, t2, t3, and t4. At the time t1, the state is the supersaturated solid solution state. At the time t2, the metastable precipitate phase is precipitated. At the time t3, a high-density stable precipitate phase is precipitated. At the time t4, a low-density stable precipitate phase is precipitated. As described above, it is found that, when the aging treatment is performed until the time t4, the aging treatment is excessive, the density of the stable precipitate phase is reduced, and the strength of the aluminum alloy is also reduced. Therefore, when the heating of the aging treatment ends at the time t3 which is an appropriate aging treatment time, the density of the stable precipitate phase increases, and the strength of the aluminum alloy increases.
Next, the precipitation state in the high strength region E1 in which the rapid cooling is performed in the rapid cooling portions 11A and 12A and the low strength region E2 (refer to Fig. 3) in which the controlled cooling is performed in the controlled cooling portions 11B and 12B of the aluminum alloy will be described with reference to Figs. 9 and 10. Fig. 9 is a graph illustrating a transition of the temperature of the aluminum alloy during the solution treatment and during the aging treatment. A solid line graph A of the solution treatment illustrates the temperature of the high strength region E1 in which the rapid cooling is performed, and a broken line graph B illustrates the temperature of the low strength region E2 in which the controlled cooling is performed. A heating holding time T is provided during the heating of the solution treatment. When the heating of the solution treatment is started and the temperature rises to a predetermined temperature, the temperature is held for the heating holding time T. The heating temperature of the aluminum alloy is preferably a temperature equal to or lower than a melting point of aluminum and equal to or higher than a solution temperature (about 500°C). A time t5 is a time when the cooling is started by the contact of the dies 11 and 12 with the aluminum alloy. The transition of the temperature up to the time t5 is the same in both the regions E1 and E2. In addition, the transition of the temperature in the aging treatment is the same in both the regions E1 and E2. A time t6 is a time when the cooling in the low strength region E2 ends. A time t7 is a time when the temperature reaches the heating temperature in the aging treatment. A time t8 is a time after the aging treatment ends.
Fig. 10 illustrates the precipitation states in the high strength region E1 subjected to the rapid cooling and in the low strength region E2 subjected to the controlled cooling at each of the times t5, t6, t7, and t8. In the high strength region E1 subjected to the rapid cooling, the supersaturated solid solution state continues until time t6. The metastable precipitate phase is precipitated at the time t7 when the aging treatment is performed. The high-density stable precipitate phase is precipitated at the time t8 after the aging treatment ends. On the other hand, in the low strength region E2 in which the controlled cooling is performed, the precipitates are already precipitated at the stage of the time t6 after the solution treatment and before the aging treatment. In addition, the precipitates are precipitated not only inside the crystal grains but also at the crystal grain boundaries. Therefore, in the low strength region E2, the number density of the precipitates in the crystal grains at the time t8 after the final aging treatment is reduced, and the strength is reduced. From the above, the metal pipe 140 after the forming may include the high strength region E1 (first portion) in which the number density of the precipitates of the alloying elements is high and the low strength region E2 (second portion) in which the number density of the precipitates of the alloying elements is lower than the high strength region E1.
Hereinafter, the operations and effects of the forming device 1 according to the present embodiment will be described.
The forming device 1 forms the metal pipe material 40 made of the aluminum alloy. For such an aluminum alloy, the aging treatment using heat is performed after the solution treatment via the forming device 1. The forming device 1 controls the cooling rate of the aluminum alloy during the solution treatment. In the aluminum alloy, the strength obtained after the aging treatment is changed depending on the cooling rate of the solution treatment. Therefore, the forming device 1 can provide, in the aluminum alloy, a portion in which the cooling rate is high and a portion in which the cooling rate is low. In this way, when the portions having the different cooling rates are provided in the aluminum alloy, the portions having the different strengths can be obtained after the aging treatment. From the above, the difference in strength can be provided in the metal pipe 140 made of the aluminum alloy after the forming.
Controlling the cooling rate may be performed by partially heating the dies 11 and 12. In this case, when the heated portions (controlled cooling portions 11B and 12B) of the dies 11 and 12 and the aluminum alloy come into contact with each other, the cooling rate of the portions is lowered. As a result, the cooling rate can be easily controlled.
The metal pipe 140 after the forming may include the high strength region E1 (first portion) in which the number density of the precipitates of the alloying elements is high and the low strength region E2 (second portion) in which the number density of the precipitates of the alloying elements is lower than the high strength region E1. The high strength region E1 has a high number density of the precipitates and high strength. The low strength region E2 has a low number density of the precipitates and low strength. In this way, the difference in strength can be provided between the high strength region E1 and the low strength region E2.
The heating holding time may be provided during the heating of the solution treatment. In this case, in the solution treatment, the time for the alloying element to be solid-solubilized can be secured. As a result, it is easy to provide the difference in strength by controlling the cooling rate.
The present disclosure is not limited to the above-described embodiment described above.
For example, a shape of the metal pipe after the forming is not particularly limited, and a metal pipe with a flange may be used, or a metal pipe without a flange may be used.
The forming device need only be a forming device that heats a metal material to perform the quenching, and a forming device using a hot stamping method may be adopted. In this case, the metal material is a plate material. Another forming device may be adopted.

[Aspect 1]

A forming device that forms a metal material made of an aluminum alloy, in which the forming device controls a cooling rate of the aluminum alloy during a solution treatment, to provide a difference in strength of the aluminum alloy after an aging treatment.

[Aspect 2]

The forming device according to Aspect 1, in which controlling the cooling rate is performed by partially heating a die.

[Aspect 3]

The forming device according to Aspect 1 or 2, in which a metal member after the forming includes a first portion having a high number density of precipitates of alloying elements, and a second portion having a lower number density of the precipitates of the alloying elements than the first portion.

[Aspect 4]

The forming device according to any one of Aspects 1 to 3, in which a heating holding time is provided during heating of the solution treatment.

[Aspect 5]

A metal member including: a first portion having a high number density of precipitates of alloying elements; and a second portion having a lower number density of the precipitates of the alloying elements than the first portion.

Reference Signs List

1: forming device
2: forming die
11, 12: die
40: metal pipe material (metal material)
140: metal pipe (metal member)
E1: high strength region (first portion)
E2: low strength region (second portion)

Claims

A forming device that forms a metal material made of an aluminum alloy,
wherein the forming device controls a cooling rate of the aluminum alloy during a solution treatment,

to provide a difference in strength of the aluminum alloy after an aging treatment.
The forming device according to Claim 1,
wherein controlling the cooling rate is performed by partially heating a die.
The forming device according to Claim 1, wherein a metal member after the forming includes
a first portion having a high number density of precipitates of alloying elements, and

a second portion having a lower number density of the precipitates of the alloying elements than the first portion.
The forming device according to Claim 1,
wherein a heating holding time is provided during heating of the solution treatment.
A metal member comprising:
a first portion having a high number density of precipitates of alloying elements; and

a second portion having a lower number density of the precipitates of the alloying elements than the first portion.