METHOD FOR MANUFACTURING OUTER PANEL

Abstract

To provide a method for manufacturing an outer panel in which takt time is shortened and of high designability. A method for manufacturing an outer panel performing a hemming process according to the present disclosure includes; performing a laser light irradiation process on an inner side of a steel sheet that serves as an outer panel to bend the steel sheet at a first angle, the laser light being irradiated along a ridgeline of a center part of a bend radius of the steel sheet, and performing the hemming process on the steel sheet at a timing that is after the laser irradiation process to bend the steel sheet at a second angle smaller than the first angle.

Claims

1. A method for manufacturing an outer panel performing a hemming process comprising: performing a laser light irradiation process on an inner side of a steel sheet that serves as an outer panel to bend the steel sheet at a first angle, the laser light being irradiated along a ridgeline of a center part of a bend radius of the steel sheet, and performing the hemming process on the steel sheet at a timing that is after the laser irradiation process to bend the steel sheet at a second angle smaller than the first angle.

2. The method according to claim 1, wherein the first angle is 110 degrees or smaller.

3. The method according to claim 1, further comprising performing a quenching process on the steel sheet at a timing that is after the laser irradiation process and before the hemming process.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0015] FIG. 1 is a diagram for describing a method for manufacturing an outer panel according to a first embodiment;

[0016] FIG. 2A is a diagram for describing the method for manufacturing an outer panel according to the first embodiment;

[0017] FIG. 2B is a diagram for describing the method for manufacturing an outer panel according to the first embodiment;

[0018] FIG. 3 is a cross-sectional photograph of an outer panel according to the first embodiment;

[0019] FIG. 4 is a diagram for describing a method for manufacturing an outer panel according to a second embodiment;

[0020] FIG. 5A is a diagram for describing an interference between an outer panel and an inner panel in a marriage process;

[0021] FIG. 5B is a diagram for describing an interference between an outer panel and an inner panel in a marriage process;

[0022] FIG. 5C is a diagram for describing an interference between an outer panel and an inner panel in a marriage process; and

[0023] FIG. 5D is a diagram for describing an interference between an outer panel and an inner panel in a marriage process.

DESCRIPTION OF EMBODIMENTS

First Embodiment

[0024] An embodiment of the present disclosure will be described below with reference to the drawings. FIGS. 1 and 2 show a method for manufacturing an outer panel according to the present embodiment.

[0025] As shown in FIG. 1, the outer panel 20 according to the present embodiment is provided with a flange 21 having such an angle that interference with the inner panel 30 due to the marriage process does not occur. Now, by irradiating a laser light 40 on the inner side of the steel sheet that serves as the outer panel 20, the steel sheet is bent at a first angle to form the flange 21.

[0026] As shown in FIG. 2A, in the laser irradiation process, the laser light 40 is irradiated along the ridgeline of a center part 41 of a bend radius of the steel sheet. By irradiating a laser light onto the steel sheet, the irradiated area and its vicinity are heated to thereby be thermally expanded. Then, as shown in FIG. 2B, the steel sheet shrinks in the direction of the arrow as it returns to a normal temperature. Therefore, bending of the flange according to the present embodiment utilizes plastic deformation using the stress generated due to thermal contraction caused by laser irradiation.

[0027] Then, a hemming process is performed in such a way that a second angle of the flange 21 is made smaller than the first angle. The amount of bending in the hemming process is reduced because the bending process is performed through laser irradiation in advance. Therefore, it is possible to reduce the number of times of the bending processes that are performed in multiple batches. In addition, since it is possible to eliminate the bending-over process of the press die, reduction in the manufacturing cost can be expected.

[0028] FIG. 3 is a cross-sectional view of a steel sheet that is subjected to a bending process by irradiating a laser light. The flat steel sheet, that is, a steel sheet having a flange formed at an angle of 180 degrees, is bent at about an angle of 30 degrees due to thermal contraction caused by laser irradiation and cooling, so that the angle of flange is about 150 degrees.

[0029] When performing a hemming process, if the angle of the flange 21 is greater than 110 degrees, the ridgeline of the flange 21 is blurred and the origin of the bending is hard to see, which compromises designability. Therefore, the first angle is preferably 110 degrees or smaller. As a result, the quality of the hemming process is improved, and it is possible to ensure designability of the outer panel.

[0030] A quenching process may be performed on the steel sheet at a timing that is before the hemming process. By performing the quenching process, the stress generated due to thermal contraction becomes large, and therefore the angle of the flange can be made small, whereby it is possible to shorten the takt time. An example of the cooling mechanism includes an air blow.

[0031] In the laser irradiation process, the amount of irradiation of the laser light 40 may be controlled by monitoring the laser heat with a temperature sensor 50. In addition, a laser torch (not shown) for emitting a laser light has a spring-type guide mechanism and may be configured to always irradiate the center of the bend radius of the steel sheet with the laser light.

[0032] In carrying out the aforementioned method for manufacturing an outer panel, the mechanism for performing a laser irradiation process and the mechanism for performing a hemming process may be arranged in the same processing line. With such a configuration, the laser irradiation process and the hemming process can be conducted simultaneously or continuously, which enables space saving and high-speed production.

[0033] In this way, it becomes possible to shorten the length of the takt time and provide a method for manufacturing an outer panel of high designability.

Second Embodiment

[0034] The present embodiment describes how to efficiently perform bending of a steel sheet using a core bar in a hemming process performed at a timing that is after the laser irradiation process. It should be noted that the same components as those in the first embodiment are denoted by the same reference symbols, and redundant descriptions thereof are omitted.

[0035] FIG. 4 shows a method for manufacturing an outer panel according to the present embodiment. A core bar 80 is placed in the vicinity of the flange 21 of a steel sheet, which serves as the outer panel 20 and which has been subjected to the marriage process with the inner panel 30, and the outer panel 20 is held by the core bar 80 and a die 70. Then, the steel sheet is hemmed using a roller 60.

[0036] By pressing the outer panel 20 with the core bar 80 and the die 70, an area where stress concentrates can be created, thus facilitating the bending process with the roller 60. This makes it possible to shorten the takt time.

[0037] In this way, it becomes possible to shorten the takt time and provide a method for manufacturing an outer panel of high designability.

[0038] It should be noted that the present disclosure is not limited to the aforementioned embodiments and can be changed as appropriate without departing from the gist of the present disclosure. For example, the present disclosure describes a manufacturing method that includes performing a hemming process, but it is not limited thereto, and the manufacturing method according to the present disclosure can be applied to the same type of processing method.

[0039] From the disclosure thus described, it will be obvious that the embodiments of the disclosure may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the present disclosure, and all such modifications as would be obvious to one skilled in the art are intended for inclusion within the scope of the following claims.