Stock material or miscellaneous articles – All metal or with adjacent metals – Intermediate article
Patent
1995-10-11
1998-08-25
Zimmerman, John J.
Stock material or miscellaneous articles
All metal or with adjacent metals
Intermediate article
428594, 428595, 428621, 29432, 29458, B21D 3900, B21D 500, B21D 516, B21C 3700
Patent
active
057981850
DESCRIPTION:
BRIEF SUMMARY
This application has been filed under 35 U.S.C. 371, claiming priority from PCT/JP94/01679 filed on 6 Oct. 1994.
TECHNICAL FIELD
The present invention relates to a joined structure and a joining method of metal plates. To explain it with examples, this invention can be utilized for joining a front panel having opening which is a structural member of a cooking apparatus with a cylindrical shell plate serving as inner case, joining in sheet metal structures of an automobile, etc.
BACKGROUND ART
Cooking apparatus (1) such as a microwave oven, oven, etc. is composed of main body (2) and door (3) as shown in FIG. 2 (A). The main body (2) is provided with an inner case (4) to make effective use of heat and prevent leakage of electric waves.
The inner case (4) is constructed with front panel (5), shell (6) and rear panel (8) as shown in FIG. 2 (B). The shell (6) has a cylindrical structure and is composed of top plate (9) and shell plate (10) with U-shaped section. The front panel (5) is provided with an opening (7) to enable putting in and taking out of object material for cooking.
The shell (6) and the front panel (5) are joined into an integral structure by caulking popularly known as curling at the front edge of the shell p)ate (10), the front edge of the top plate (9) and the periphery (7A) of the opening (7) (see JP-U-59-41444).
In the opening (7) of the front panel (5), a folded part (7B) is formed on the entire circumference in preparation for curling. Moreover, at the front edges of the top and shell plates (9,10) constituting the shell (6). folded parts (9B, 10B) are formed, respectively, as joining means corresponding to the folded part (7B) on the front panel (5) side.
The joining of the front panel (5) and the front edge of the shell (6) into an integral body is performed by putting the folded part (7B) on the front panel (5) side and the folded parts (9B, 10B) on the shell (6) side one upon the other and applying a load P in the direction X, as shown in FIG. 3 (A).
As it is understood from FIG. 3 (A), the respective folded parts (7B, 9B, 10B) form a solid joined structure not producing any deviation in their mutual joining positions even when the circumference of opening (7A) of the front panel (5) is pulled in the direction Y or when the front edge (9B) of the top plate (9) or the front edge (10B) of the shell plate (10) is pulled in the direction Y', by having their respective tip parts held inside the folded part of their counterparts.
However, when, in the joined structure as shown in FIG. 3 (A), a tensile load in the direction opposite to above acts, i.e., if the circumference of opening (7A) of the front panel (5) is pulled in the direction Y' or the front edge (9B or 10B) of the top plate (9) or the shell plate (10) is pulled in the direction Y, the joined structure loses its joining strength, producing a mutual displacement among the front panel (5), the top plate (9) and the shell plate (10) because no fastening means is provided in the direction of movement of the respective folded parts (7B, 9B, 10B).
Therefore, the joining system by curling shown in FIG. 3 (A) could not provide any joined structure capable of demonstrating a solid joining strength in all directions.
To solve such problem, in the prior art according to JP-U-58-41411, JP-A-59-119118, JP-Y-1-38418, etc, form, in a heating chamber of a microwave oven constructed by caulking the inner case (4) and the front panel (5), in which, as shown in FIG. 3(B), a plural number of projections (11) are formed at prescribed intervals on one of the inner case (4) and the front panel (5), e.g. on the front panel (5) and a plural number of holes (12) are formed at the same intervals as those of the projections (11) on the other, e.g. in the top plate (9) and the shell plate (10), so that the projections (11) are received in the holes (12) as a result of curling, thereby preventing separation of the inner case (4) from the front panel (5).
In the prior art as shown in FIG. 3 (C), cut and raised portion, or tongues (11A) are provided at p
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JP-A-57 206533, Dec. 17, 1982. JP-A-03 201498, Sep. 3, 1991.
LaVilla Michael
Sanyo Machine Works, Ltd.
Zimmerman John J.
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