JP2001293522A - Aluminum or aluminum alloy plate having bent part and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an aluminum or aluminum alloy plate having a crackless bent part not easily cracked in a simple method and to provide a manufacturing method of an aluminum or aluminum alloy plate having good bending workability. SOLUTION: A coining part 4 is formed to a bending part, ahead of bending, in a plate material 3 forming an outer material of an automobile panel material. A plate thickness decreasing rate in coning is 10-50% as thin as a thickness before the coining process, preferably 20-40%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aluminum or aluminum alloy plate having a bent portion having no crack and an aluminum or aluminum plate having a bent portion capable of bending an aluminum or aluminum alloy plate with good bending workability. The present invention relates to a method for manufacturing an alloy plate.

[0002]

2. Description of the Related Art Conventionally, steel sheets are often used as molding materials for automobile parts and electric parts.
The application of aluminum alloy materials has been studied for the purpose of reducing the weight of these automobile parts and electric parts, and some of them have begun to be put into practical use.

[0003] In forming these components, bending may be performed after drawing and stretch forming or simultaneously with drawing and stretch forming. In particular, in an automobile panel such as a hood, as shown in FIG. 2, an inner member 1 on the inner side of the vehicle body and an outer member 2 on the outer side of the vehicle body are overlapped to form an outer member 2.
Of the outer material 2 and the inner material 1
It is manufactured by combining However, the aluminum alloy sheet has a problem that the elongation is small and the bending workability is inferior to the steel sheet, so that cracking or springback is likely to occur during bending.

In Japanese Patent Application Laid-Open No. Hei 7-148527, a concave portion having a reverse direction is once formed in a bent portion, and then the reverse concave portion is bent in a regular direction as a fold line to obtain a stress in a plate thickness direction. A method has been proposed in which the distribution difference is made uniform to suppress springback during bending.

Further, Japanese Patent Application Laid-Open No. 9-262624 discloses a method for hemming a plate material which can prevent breakage and rough skin at a bent portion when the plate material is hemmed at 180 °. . In this method, the step of bending the plate material by 90 ° and the pressing of a hemming jig having a contact surface corresponding to the curved surface of the bent portion of the plate material while pressing the free end side between 90 ° and 180 ° are performed. And a step of bending the free end side so as to be flat at a bending angle of 180 °.

Further, Japanese Patent Application Laid-Open No. H11-309527 discloses a hemming device that continuously bends the peripheral portion of a workpiece while applying vibration to a processing surface having a convex curved surface of a hem blade. A hemming device modified to increase the hemming speed is disclosed.

[0007]

However, in the method of bending an aluminum alloy plate disclosed in Japanese Patent Application Laid-Open No. Hei 7-148527, a forming method for preventing springback is disclosed. No mention is made, and no bending method for suppressing cracking is disclosed.

The hemming method disclosed in Japanese Patent Application Laid-Open No. 9-262624 has a drawback that the steps are complicated.

Further, the hemming device disclosed in Japanese Patent Application Laid-Open No. H11-309527 has a drawback that the device is complicated, and the present invention has been made in view of such a problem, and is easily realized by a simple method. It is an object of the present invention to provide an aluminum or aluminum alloy plate having a sound bent portion and an aluminum or aluminum alloy plate having a good bending workability, which can obtain an aluminum alloy plate having a bent portion having no cracks. I do.

[0010]

In the aluminum or aluminum alloy plate having a bent portion according to the present invention, the bent portion is coined along the bending axis, and the thickness reduction rate due to the coining is reduced by coining. It is characterized in that it is 10 to 50%, preferably 20 to 40% of the plate thickness before processing.

The method of manufacturing an aluminum or aluminum alloy plate having a bent portion according to the present invention is intended to reduce the thickness of the aluminum alloy plate by 10 to 50%, preferably 20 to 40%, at the portion to be bent. It is characterized by having a step of coining along the bending axis and a step of bending at the coining portion.

[0012] The coining is a processing method in which a tool is pressed against an aluminum alloy plate to locally reduce the thickness of this portion. That is, it is not thinned by grinding or the like. When this coining part is bent, this part has a reduced thickness, so that it can be easily bent and cracks can be prevented, and a sound bent part without cracks Can be easily formed by a simple process.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described.
This will be specifically described with reference to the accompanying drawings. FIG. 1 is a diagram showing a method for bending an aluminum alloy plate according to an embodiment of the present invention. In this embodiment, the present invention is applied to an automobile panel.

As shown in FIG. 1A, in the present invention, first, a plate material 3 made of aluminum or an aluminum alloy is used.
Is subjected to coining to form a coined portion 4. In this coining process, a tool is pressed against the surface of the plate material 3 to form a concave portion.

When this plate material 3 is applied to an outer material of an automobile panel, as shown in FIG. 1B, the plate material 3 as an outer material is superimposed on an inner material 5 made of aluminum or an aluminum alloy, and a coining portion is formed. At 4, the plate 3 is bent at 180 °, and the end of the inner member 5 is sandwiched between the plates 3. Thereby, the inner member 5 and the plate member 3 as the outer member are joined.

The outer panel of an automobile panel is bent by 180 ° bending while sandwiching the inner panel. Conventionally, when the outer panel is thick or when the strength is increased by work hardening, etc. And cracking defects may occur. In the present invention, before bending the aluminum alloy plate, the portion to be bent is subjected to coining along the bent portion, the thickness of the bent portion is reduced, and the reduction ratio of the thickness is appropriately defined. . By performing coining in advance in this way, bending workability is improved.

When the thickness of a bent portion is reduced by coining before bending to improve the bending workability, the thickness reduction rate is 10% of the thickness before coining.
If it is less than 3, the effect of improving bending workability is not sufficient. On the other hand, if it exceeds 50%, work hardening due to coining becomes too large, and conversely, bending workability is deteriorated and cracks occur during coining. For this reason, the sheet thickness reduction rate due to coining of the bent portion is set to 10 to 50% of the sheet thickness before coining.

In the present invention, after the coining process is performed along the bent portion, the inner material 5 and the outer plate material 3 are joined by the 180 ° bending process. The occurrence of cracks can be prevented.

[0019]

EXAMPLES Examples of the present invention will be specifically described below in comparison with comparative examples that fall outside the scope of the claims. Using an Al-4.5 mass% Mg alloy plate with a plate thickness of 1 mm as a test material, simulating press forming before bending, performing a 5% stretch, coining the bent portion, and performing a bending test Was done. Furthermore, as a severe bending condition,
A test was also conducted on a sample subjected to a 10% stretch before bending. The bending test conditions are JIS
Using the No. 3 test piece specified in Z 2204, JIS
The bending test piece according to the V-block method specified in Z2248 was further subjected to a 180 ° bending test by the press bending method specified in JISZ2248.

Then, the state of cracks on the surface of the bent portion of the test piece after the test was visually observed with a magnifier of 10 times magnification. As a result, the sample was evaluated as 5 on a scale of 5 where cracks and rough skin did not occur on the surface of the bent portion, and 1 on the basis of a crack after the bending test or during coining. That is,
In the evaluation of the indices 1 to 5, in the case of the highest “5”, the bendability was the best, and in the case of the lowest “1”, the bendability was the lowest, and cracks occurred after the bending test or during coining. . The evaluation “3” is intermediate, and the evaluation “4” or “2” is higher or lower than the evaluation “3”, respectively. For example, in the evaluation “3”, slight cracking occurred, but in the evaluation “4”, the surface was not cracked but slightly roughened.

The results are shown in Table 1 below. As shown in Table 1 below, Example No. In Nos. 1 to 4, the sheet thickness reduction rate after coining was within the range of the present invention, and thus good bending workability was obtained. In particular, in Example No. 2,
In No. 3, since the amount of coining is the most appropriate within the range of claim 2, good bendability is obtained even in the case of a 10% stretch material under severe bending test conditions.

On the other hand, in Comparative Example No. In Nos. 5 and 6, the sheet thickness reduction rate after coining was less than the lower limit of the present invention, the effect of improving bending workability was not sufficient, and roughening or cracking occurred after bending. Also, in Comparative Example No. 7 and 8
The sheet thickness reduction rate after coining exceeded the upper limit of the present invention, cracking occurred during bending, and bending workability was poor.

[0023]

[Table 1]

[0024]

As described above, according to the present invention,
Since the coining process with an appropriate thickness reduction rate is performed before the bending process, the occurrence of cracks and rough surfaces during the bending process is prevented. Thereby, according to the present invention, good bending workability can be obtained at the time of bending, and an aluminum or aluminum alloy material having a bent portion free from cracks and rough surfaces can be obtained.

[Brief description of the drawings]

FIGS. 1A and 1B are diagrams showing an embodiment in which the present invention is applied to an automobile panel material.

FIG. 2 is a cross-sectional view showing a conventional automobile panel material.

FIG. 3 is a perspective view showing a relationship between a bending direction and a bending axis when the present invention is applied to an automobile panel material.

[Explanation of symbols]

 1, 5: inner material 2: outer material 3: plate material 4: coining part

Claims (4)

[Claims] A coining process is performed on a bent portion along a bending axis, and a reduction rate of the sheet thickness by the coining process is 10 to 50% of a sheet thickness before the coining process. Or an aluminum alloy plate having: 2. The aluminum or aluminum alloy sheet having a bent portion according to claim 1, wherein the sheet thickness reduction rate is 20 to 40% of the sheet thickness before coining. 3. A step of coining along a bending axis so that a thickness of the portion to be bent of the aluminum or aluminum alloy plate is reduced by 10 to 50%, and a step of bending at the coining portion. The manufacturing method of the aluminum or aluminum alloy board which has a bending part characterized by having. 4. The method for manufacturing an aluminum or aluminum alloy sheet having a bent portion according to claim 3, wherein the sheet thickness reduction rate by said coining is 20 to 40% of the sheet thickness before coining. .