JP2011063868A - Methods for manufacturing aluminum molded component and metal structure including the aluminum molded component - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently manufacturing a high strength aluminum molded component and a metal structure including the aluminum molded component, with excellent moldability. <P>SOLUTION: The method for manufacturing an aluminum molded component 1 includes: a heating process for heating a plate material 1A composed of a precipitation hardening type aluminum alloy to ≥450°C; a pressing process for press molding the heated plate material 1A into a prescribed shape in a mold 3; and a cooling process for cooling the resulting plate material 1A at a cooling speed of ≥10 °C/sec in a pressed state in the mold 3. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method of manufacturing a part by forming a plate made of an aluminum alloy, and a method of manufacturing a metal structure including the molded product.

  Sheet metal products such as automobile bodies are often required to have improved strength and light weight at the same time. In particular, there is a high demand for the body of an automobile, and recently, a steel sheet with a significantly increased strength called an ultra-high tensile material has begun to be adopted.

  On the other hand, a plate made of an aluminum alloy is considerably lighter than a steel plate, but is inferior in strength, and its improvement has been demanded. Under such circumstances, research on a high-strength aluminum alloy has been advanced, and for example, a JIS 7000 series alloy called ultra-super duralumin has been developed.

  However, a high-strength aluminum alloy material such as the above-mentioned 7000 series alloy has a disadvantage that it is inferior in formability, so that, for example, the degree of freedom in shape at the time of press molding is limited, or division molding is required. There was a problem. For these reasons, high strength aluminum alloy materials can be used only in limited parts of the product, and there are cases where additional reinforcing members are required at important points. Thus, even if the strength of the aluminum alloy material is improved, unless compatibility with formability is achieved, there is a problem that productivity is lowered and cost is increased.

  Regarding the high-strength aluminum alloy as described above, for example, Patent Document 1 below discloses a method for producing an Al—Zn—Mg—Cu alloy material typified by 7000 series. Specifically, in Patent Document 1, after homogenizing a continuous cast material of an aluminum alloy having the above composition, it is processed by hot working or cold working, or a combination of both workings. Through a process of quenching to a predetermined temperature in the range of 150 ° C. to 350 ° C., holding at the predetermined temperature for 1 second to 30 minutes, water cooling, and then performing natural aging or artificial aging treatment Manufactures aluminum alloy materials. According to such a method, it is said that a high-strength aluminum alloy material excellent in stress corrosion cracking resistance can be produced.

JP 2009-13479 A

  However, since the method disclosed in Patent Document 1 is subjected to steps such as solution treatment, quenching, and temperature holding after cold working or hot working, the total production time is increased. There is a problem that it takes. Further, for example, when the material is processed by cold working, there is a problem that the formability is poor and the degree of freedom of shape is greatly limited.

  The present invention has been made in view of the above circumstances, and an object thereof is to efficiently produce a high-strength aluminum molded part and a metal structure including the same with excellent moldability.

  In order to solve the above problems, the present invention is a method of manufacturing a part by forming a plate made of an aluminum alloy, and heating the plate made of a precipitation hardening type aluminum alloy to a temperature of 450 ° C. or higher. A heating step, a pressing step in which the heated plate material is pressed in a mold to form a predetermined shape, and the plate material is cooled at a cooling rate of 10 ° C./second or more while being pressed in the mold. And a cooling step to be performed (claim 1).

  In the present invention, a plate material made of a precipitation hardening type aluminum alloy is heated to 450 ° C. or more, so that the material is softened and the precipitation hardening element in the alloy is dissolved in the matrix of aluminum. And it presses with a metal mold | die in this state, Then, it cools with the comparatively rapid cooling rate of 10 degree-C / sec in the metal mold | die. According to this method, a high-strength aluminum molded part can be efficiently produced with excellent formability.

  That is, since the plate material is pressed after heating, there is an advantage that it is excellent in formability and has a high degree of freedom in part shape. In addition, for the same reason, there is no fear of a springback (return phenomenon of shape) that easily occurs during cold pressing, and since cooling is performed in the mold, thermal distortion can be minimized. The dimensional accuracy can be further improved. Furthermore, although the solid solution state is maintained immediately after the completion of cooling due to the rapid cooling after the solid solution, the alloy element dissolved in a time is precipitated with the passage of time, the crystal is hardened, and the strength is increased. For this reason, it is possible to increase the strength of the component by simply leaving it at room temperature, and it is possible to manufacture a higher-strength component with excellent production efficiency.

  The heating temperature in the heating step is more preferably set in a temperature range of 450 ° C. or higher and 550 ° C. or lower (claim 2).

  In the cooling step, cooling at 10 ° C./second or more is preferably continued until the plate material is at least 150 ° C. or lower (claim 3). More preferably, cooling at 10 ° C./second or more is continued until the temperature reaches 100 ° C. or lower.

  The material of the plate material is not particularly limited as long as it is a precipitation hardening type aluminum alloy, but preferable examples include 2000 series, 6000 series, or 7000 series aluminum alloys defined in JIS standards. (Claim 4).

  The present invention also relates to a method of manufacturing a metal structure including an aluminum molded part, wherein the aluminum molded part manufactured by the above-described method is assembled with other parts, and then painted, dried, and naturally left at room temperature. It is characterized in that it is aged (claim 5).

  According to this method, after manufacturing a metal structure using aluminum molded parts, the strength naturally increases in the process of storage and transportation, so that the strength of the product can be increased without deteriorating the production efficiency. it can.

  As described above, according to the present invention, a high-strength aluminum molded part and a metal structure including the same can be efficiently manufactured with excellent formability.

It is a figure for demonstrating the procedure of a heating process. It is a figure for demonstrating the procedure of a press process. It is a figure for demonstrating the procedure of a cooling process. It is a figure for demonstrating a mode that an aluminum molded component is taken out from a metal mold | die. It is a table | surface which shows the manufacturing condition of an Example and a comparative example, and the measurement result of tensile strength. It is a graph which shows the time change of the tensile strength of Examples 5 and 6.

(1) Manufacture of aluminum molded part FIGS. 1-4 is a figure for demonstrating the manufacturing method of the aluminum molded part concerning one Embodiment of this invention. The manufacturing method of the present embodiment includes the following heating process, pressing process, and cooling process.

(1-1) Heating Step To manufacture the aluminum molded part 1 (FIG. 4), first, as shown in FIG. 1, a heating step of heating the aluminum alloy plate 1A as a material is performed. Specifically, the plate material 1A is charged into a heating furnace 2 made of, for example, an electric furnace or a gas furnace, and heated to a temperature of 450 ° C. or higher (preferably a temperature range of 450 ° C. or higher and 550 ° C. or lower). The material of the plate material 1A is a precipitation hardening type aluminum alloy, and suitable examples thereof include 2000 series (Al-Cu-Mg series), 6000 series (Al-Mg-Si series), or JIS standards. An alloy of 7000 series (Al-Zn-Mg-Cu series) can be given.

  Since the plate material 1A is a precipitation hardening type aluminum alloy, the precipitation hardening element dissolves in the matrix of aluminum in the plate material 1A when heated to the above temperature range (450 ° C. or higher). . Moreover, by heating to the above temperature range, the plate material 1A becomes softer than that at normal temperature, and can be easily pressed as described later. That is, the heating step is performed for the purpose of dissolving the precipitation hardening element (solution treatment) and improving moldability by softening the material.

(1-2) Pressing Step Next, as shown in FIG. 2, a pressing step for press-molding the plate material 1A after heating is performed. Specifically, the core mold 5 is pressed in the insertion direction of the cavity mold 4 by a mold clamping device (not shown) in a state where the plate material 1A is set in the press mold 3 having the cavity mold 4 and the core mold 5. Thus, the plate material 1A is deformed into a shape corresponding to the gap (molding space) between the cavity mold 4 and the core mold 5 (see FIG. 3).

  The cavity mold 4 and the core mold 5 are provided with water jacket portions 4a and 5a, respectively. When the plate 1A is press-formed, cooling water is introduced into the water jacket portions 4a and 5a, and the mold 3 is cooled and maintained at a substantially constant temperature by the action of the cooling water. ing.

  Since the press molding in the mold 3 is performed in a state where the plate material 1A is softened in the previous heating step, the plate material 1A is deformed relatively easily. Therefore, for example, a spring back (return phenomenon of shape) which becomes a problem at the time of cold pressing does not occur later, and the dimensional accuracy after press forming is sufficiently ensured.

(1-3) Cooling process Next, the cooling process which cools the board | plate material 1A after a press is performed. Specifically, as shown in FIG. 3, the plate material 1A is cooled by holding the plate material 1A pressed by the mold 3 in the mold for a predetermined time. That is, since the mold 3 into which the cooling water is introduced is maintained at a relatively low temperature, the plate material 1A is held inside the mold 3 and left for a predetermined time, so that the comparison is made. The plate material 1A is cooled at a rapid cooling rate. When the mold 3 is quite large and has a sufficient heat capacity, the temperature can be stabilized without forced cooling with cooling water, and thus cooling with cooling water as described above is not necessarily required.

  The cooling step is continued until the plate material 1A is lowered to at least 150 ° C. or less, preferably 100 ° C. or less. The cooling rate of the plate 1A during this period is at least 10 ° C./second or more.

  Thus, in the cooling step, the cooling is performed while being pressed by the mold 3, so that the thermal distortion can be minimized as compared with the case where the cooling is performed after removing from the mold 3.

  When the above cooling process is completed, as shown in FIG. 4, the mold 3 is separated from the mold, and the aluminum molded part 1 (that is, the plate material 1 </ b> A formed into a desired shape through each of the above processes) is taken out. The aluminum molded part 1 is completed through the above steps.

(2) Manufacture of metal structure using aluminum molded part Next, a method for manufacturing a metal structure such as a car body of an automobile using the aluminum molded part 1 manufactured by the method (1) will be briefly described. Explained.

  In order to manufacture the metal structure, first, the aluminum molded part 1 is assembled with other parts by means such as welding or bolt fastening, and then necessary paint is applied and dried. Here, “other parts” means that the aluminum molded part 1 is excluded from various parts constituting the metal structure, and the material thereof is not limited to an aluminum alloy. For example, it may be a metal part other than an aluminum alloy made of a steel plate or the like, or may be a resin part.

  The metal structure including the aluminum molded part 1 manufactured as described above is then temporarily stored in a factory or transported to a predetermined delivery location. In this case, age hardening occurs during the above storage and transportation, and the strength thereof is increased.

  That is, as explained in (1) above, the aluminum molded part 1 is formed into a solution by heating at 450 ° C. or higher, then pressed by the mold 3 and further cooled at a cooling rate of 10 ° C./second or higher. Manufactured. In this way, the aluminum molded part 1 is in a state in which the precipitation hardening element remains in a solid solution in the aluminum matrix immediately after being taken out of the mold 3 by undergoing a process of rapid cooling after solution treatment. It has become.

  However, the state in which the precipitation hardening element is in a solid solution cannot be stabilized at room temperature. For this reason, when the aluminum molded part 1 is allowed to stand at room temperature, the dissolved alloy elements gather to form a compound (intermetallic compound) and gradually precipitate from the matrix. This precipitate is deposited relatively uniformly over a long period of time, thereby strengthening the dispersion of the metal particles. That is, the metal crystal is distorted in various places by the precipitation, so that the crystal slip (dislocation) hardly occurs and the crystal becomes harder.

  As described above, the aluminum molded part 1 has a phenomenon that its strength increases with the passage of time at room temperature. Therefore, when the aluminum molded part 1 is used as a part of a metal structure, the strength of the aluminum molded part 1 is increased during storage and transfer after manufacture, or even after delivery to the user. The strength of the whole body will increase. Further, since it is only necessary to leave it at room temperature, there is no need to perform any special treatment, and there is an advantage that the strength can be increased without deteriorating the production efficiency.

(3) Example Next, the result of the experiment performed in order to confirm the effect by the above manufacturing methods is demonstrated. Specifically, in this experiment, an aluminum molded part 1 was actually manufactured by the method described in (1) above, and its tensile strength was measured and compared.

(3-1) Experimental conditions FIG. 5 is a table showing the results of producing samples of the aluminum molded part 1 under a plurality of conditions with different materials and cooling rates, and measuring the tensile strength in stages before and after completion. . Among each case shown by this figure, Examples 1-6 are the cases which manufactured the aluminum molded component 1 along the manufacturing method (procedure shown in said (1)) of this invention, and a comparative example is This is a case manufactured by a method different from the present invention. Below, the conditions of each Example and a comparative example are demonstrated.

Examples 1 and 2
In Examples 1 and 2, an aluminum molded product 1 was manufactured using a JIS 2000 alloy. However, the cooling rate in the cooling process is different between the above-described two examples, which is 10 ° C./second in Example 1 and 40 ° C./second in Example 2. The original heating temperature (furnace temperature in the heating process) was the same, both set to 470 ° C. In addition, each said cooling rate (10 degreeC / second, 40 degreeC / second) is a cooling rate until temperature becomes 100 degrees C or less at least. That is, the minimum cooling rate until cooling to 100 ° C. or less is 10 ° C./second in Example 1, and 40 ° C./second in Example 2 (this is another example and comparative example). But the same).

Examples 3 and 4
In Examples 3 and 4, an aluminum molded product 1 was manufactured using a JIS6000-based alloy. The cooling rate is 10 ° C./second in Example 3, 40 ° C./second in Example 4, and both heating temperatures are 470 ° C.

Examples 5 and 6
In Examples 5 and 6, an aluminum molded product 1 was manufactured using a JIS7000 alloy. The cooling rate is 10 ° C./second for Example 5, 40 ° C./second for Example 6, and the heating temperature is 470 ° C. for both.

-Comparative example In the comparative example, the aluminum molded product 1 was manufactured using the JIS7000 type alloy. The cooling rate is 2 ° C./second, and the heating temperature is 470 ° C.

  In addition, the JIS2000 series, 6000 series, and 7000 series alloys used in each of the above Examples and Comparative Examples contain the following components as components other than aluminum (numerical values are mass%).

2000 series: Cu: 2.0 to 5.0, Mg: 0.2 to 2.0, Si: 0.01 to 1.2, Mn: 0.01 to 1.2
6000 series: Mg: 0.4 to 1.5, Si: 0.2 to 1.0, Cu: 0.01 to 0.4, others: Mn, Cr
7000 series: Zn: 4.0-9.0, Mg: 0.5-4.0, Cu: 0.01-3.0, others: Mn, Cr

(3-2) Experimental results Using the samples of the aluminum molded product 1 according to Examples 1 to 6 and the comparative example, the tensile strength was measured at each stage before heating, 1 day after holding at room temperature, and 7 days after holding at room temperature. This is also shown in FIG. Note that “before heating” means a state before being heated in the heating process, and after 1 day of holding at room temperature, “after 1 day of holding at normal temperature” means that the sample completed through the heating process, pressing process and cooling process is left for 1 day at room temperature, and after 7 days of holding at room temperature Is a state where 7 days have passed since the completion of the standing time.

  As is apparent from FIG. 5, in any case of Examples 1 to 6, the strength increased after 1 day at room temperature after completion, compared to the tensile strength before heating, and 7 days passed. It can be seen that the strength is further increased.

  For example, in Example 5 manufactured using a JIS7000 alloy at a cooling rate of 10 ° C./second, the tensile strength before heating is 428 MPa, whereas the strength increases to 435 MPa after 1 day of holding at room temperature. In addition, after 7 days at room temperature, the temperature further increased to 492 MPa. Further, in Example 6 in which the cooling rate was increased to 40 ° C./second while using a JIS 7000 series alloy, the strength increased to 458 MPa after 1 day of normal temperature holding, compared to the tensile strength of 428 MPa before heating. After 7 days of retention, the pressure increases to 525 MPa.

  FIG. 6 is a graph showing temporal changes in tensile strength in Examples 5 and 6. As is clear from this graph, Example 6 with a cooling rate of 40 ° C./second has higher strength (age hardening) over time than Example 5 with a cooling rate of 10 ° C./second. It can be seen that the degree is large. This is also seen in the cases of Examples 1 and 2 or Examples 3 and 4 using other materials (2000 series, 6000 series). From the above, it can be seen that the faster cooling rate increases the enhancement effect by age hardening.

  On the other hand, in the comparative example with a slow cooling rate of 2 ° C./second, the strength was increased only to 452 MPa even after 7 days at room temperature, the same material and the fast cooling rate of 10 ° C./second in Example 5 above. It can be seen that the increase in strength is considerably smaller than that in FIG.

  In Examples 1 to 6, the heating temperature in the heating process was set to 470 ° C., but considering the solution temperature of the precipitation hardening type aluminum alloy, the range of about 450 ° C. to 550 ° C. If the heating temperature is set to, it is considered that the same effect as the above embodiment can be obtained.

1 Aluminum molding parts 1A Sheet material 3 Mold

Claims (5)

A method of manufacturing a part by forming a plate made of an aluminum alloy,
A heating step of heating a plate material made of a precipitation hardening type aluminum alloy to a temperature of 450 ° C. or higher;
A pressing step of pressing the heated plate material into a predetermined shape by pressing in a mold;
And a cooling step of cooling the plate material at a cooling rate of 10 ° C./second or more while being pressed in the mold. In the manufacturing method of the aluminum molded component of Claim 1,
The said heating process WHEREIN: The said board | plate material is heated to the temperature range of 450 degreeC or more and 550 degrees C or less, The manufacturing method of the aluminum molded component characterized by the above-mentioned. In the manufacturing method of the aluminum molded component of Claim 1 or 2,
In the cooling step, the cooling of 10 ° C./second or more is continued until the plate material is at least 150 ° C. or less. In the manufacturing method of the aluminum molded component of any one of Claims 1-3,
A method for producing an aluminum molded part, characterized in that a 2000 series, 6000 series, or 7000 series aluminum alloy sheet defined in JIS standards is used as the plate. A method of manufacturing a metal structure including aluminum molded parts,
5. A metal structure characterized in that an aluminum molded part manufactured by the method according to any one of claims 1 to 4 is assembled with another part, and then painted, dried, and naturally aged at room temperature. Manufacturing method.

Images