JPH0138418Y2 - - Google Patents

Description

[Detailed Description of the Invention] Field of the Invention This invention relates to an inner box for a cooking appliance, and particularly to a structure of an inner box for a cooking appliance such as a microwave oven or an oven with improved joints.

Description of Prior Art FIG. 1 is an external perspective view showing an example of a microwave oven to which this invention is applied. Microwave oven 1 is
It consists of a main body 2 and a door 3. The main body 2 includes an inner box 4. In a heating cooking device such as a microwave oven, an inner box 4 is provided in order to effectively utilize heat and prevent radio wave leakage.
is said to have a double structure.

As shown in the schematic perspective view of FIG. 2, the inner box 4 is composed of a front plate 5, a body 6, and a rear plate (not shown). The body part 6 has a cylindrical structure and consists of a top plate 9 and a body plate 10 having a U-shaped cross section. The front plate 5 is provided with an opening 7 to allow food to be taken in and out. The body portion 6 and the front plate 5 are joined by curling at the front edge of the body plate 10, the front edge of the top plate 9, and the peripheral edge 7a of the opening 7. Although not shown, the body 6
and the rear plate are joined at the rear edge 10b of the body plate 10, the rear edge 9b of the top plate 9, and the outer peripheral edge of the rear plate.

FIG. 3 is a partially cutaway perspective view showing in detail the structure of the joint portion of the inner box 4 shown in FIG. 2. FIG. Inner box 4
All joints are formed by curling. That is, the front plate 5 and the body plate 10, the front plate 5 and the top plate 9, the body plate 10 and the rear plate 9, and the top plate 9 and the rear plate 8 are all joined by curling.

By the way, a bent portion is formed on the opening peripheral edge 7a of the front plate 5 over the entire circumference. Further, bent portions are also formed on the front edge of the top plate 9 and the front edge of the body plate 10 that constitute the body portion 6, respectively. The front plate and the front edge of the body are connected by curling after the respective bent portions are overlapped. FIG. 4 explains the joining state of the bent portion 7b formed on the opening peripheral portion 7a of this front plate and the bent portion 9c formed on the front edge of the top plate 9 constituting the body portion 6. FIG. As is clear from FIGS. 4 and 5, the bent portion 7b and the bent portion 9c are moved and pressed by a mold in the directions of arrows A and B, respectively, and are subjected to a curling process.

As is clear from FIG. 5, the opening peripheral edge 7a of the front plate and the front edge 9a of the top plate are overlapped and firmly joined to each other so as to sandwich the bent portions 7b and 9c of the other. has been done. In particular, even if the opening peripheral edge 7a of the front plate is pulled in the direction of the arrow X and the front edge of the top plate is pulled in the direction of the arrow (-X), a strong bonding structure is maintained. This is because the tip of each bent portion 7b, 9c abuts the inner side of the other bent portion 9c, 7b. However, if the opening peripheral edge 7a of the front plate is pushed in the direction of the arrow (-X) and the front edge of the top plate is pushed in the direction of the arrow (X), it is no longer possible to maintain a strong joint structure. I can't. In the direction in which each bent portion 7b, 9c moves, each bent portion 7b,
This is because there is no part that locks 9c. For this reason, if the force applied to the opening periphery 7a of the opening 7 and the front edge 9b of the top plate 9 is relatively large, the joint may be misaligned. Furthermore, if the applied force is abnormally large, the bond itself may come undone. Therefore, the curling joint structure shown in FIGS. 4 and 5 does not provide a strong joint in any direction.

In order to solve these problems, the
-137761 (Utility Model Application No. 58-41411) is a heating chamber of a microwave oven constructed by folding a box body and a front plate. Discloses a heating chamber for a microwave oven in which the box body and the front plate are prevented from coming off by fitting a plurality of small protrusions with a plurality of small holes formed in either one of the other parts. are doing. By the way, in this prior art, it is necessary to fit all the small protrusions into all the small holes, and if even one is misaligned, the curling process will be defective. Therefore, it is necessary to accurately align all small protrusions and all small holes. However, the operation of accurately aligning all the small protrusions with all the small holes is a very complicated operation, which poses a problem in that a great deal of labor is required at the stage of manufacturing the heating chamber.

Further, in this prior art, in order to easily fit all the small protrusions into all the small holes, it was necessary to make the diameter of the small protrusions slightly smaller than the diameter of the small holes. As a result, after crimping, a gap is created between the small protrusion and the hole, and if the crimping force is weak, the position of the small protrusion may shift, causing a problem.

Purpose of the invention Therefore, the purpose of this invention is to eliminate the above-mentioned drawbacks, to provide a curling joint that achieves a strong joint in all directions, especially in the direction in which the joint is separated, and that is easy to manufacture. An object of the present invention is to provide an inner box for a cooking appliance having a portion.

Structure of the device This device includes a front plate having an opening, a cylindrical body, a bent portion provided around the opening of the front plate, and a bent portion provided at the front edge of the body. The one bent part is provided with a hole, the other bent part is provided with a protrusion that fits into the hole, and the one bent part and This invention relates to an inner box of a cooking appliance that is joined to the other bent portion by caulking. In order to solve the above-mentioned problem, the protrusion includes a portion having a larger dimension than the diameter of the hole, and the larger portion is crimped into the hole. It is characterized in that it fits into the hole while being formed by the wall surface of the hole.

Effects of the Device As described above, according to this device, the protrusion provided on one of the bent portions includes a portion having a larger dimension than the hole provided on the other bent portion,
This large-sized portion is fitted into the hole while being shaped by the wall surface of the hole by caulking. Therefore, when performing the curling process to obtain the above-mentioned joining structure, a space defined by the front plate and a bent part provided at the edge of the opening of the front plate is provided at the front edge of the body. It is sufficient to simply fit the folded portion. That is, it is sufficient to roughly align the protrusions and holes, and accurate alignment between the protrusions and holes is not necessary. The operation of fitting the protrusion into the hole is performed during the caulking operation. Since the joint structure is formed through such a simple process, the inner box of the cooking appliance can be manufactured very easily.

In addition, the protrusion includes a portion having a larger dimension than the diameter of the hole, and this larger portion is fitted into the hole while being formed by the wall surface of the hole by caulking. Since the protrusion is embedded in the hole, the protrusion is reliably embedded in the hole, and no gap is created between the protrusion and the hole. Therefore, even if the caulking force is somewhat weak, the small protrusions will not be misaligned and no rattling will occur.

Other features of this invention will become clear from the description of the following embodiments.

DESCRIPTION OF EMBODIMENTS FIG. 6 is a perspective view showing a process for manufacturing an embodiment of this invention. The body plate 10 has three curling margins 11A, 11B on one longitudinal side of the plate made of a metal material such as stainless steel.
11C and flange portions 12A, 12B, and three curling margins 13A, 13B, 13C and flange portion 14 are formed on the other longitudinal side.
A, 14B are formed, one curling margin 15A, 15B is formed on each of the other two sides, and then the entire board is bent so that the longitudinal sides become U-shaped. Curling margins 16, 17, 18, and 19 are formed on the outer peripheral edges of the top plate 9, respectively. Curling margins 20A, 20B, 20C, and 20D are formed on the outer peripheral edges of the rear plate 8, respectively.

The top plate 9, body plate 10, and rear plate 8, each having a curling margin formed in this way, are joined in the following manner. First, the top plate is 9 for the body plate 10.
are combined in the direction of arrow P in FIG. Next, the curling margin 17 of the top plate, the curling margin 15B of the body plate, and the curling margin 19 of the top plate and the curling margin 15A of the body plate are respectively joined by curling processing. After the top plate 9 is joined to the body plate 10 by curling, the rear plate 8 is assembled to the body plate 10 in the direction of arrow Q in FIG. Next, the curling margin 11A of the body plate and the rear plate 8
curling allowance 20B, curling allowance 11B of body plate 10, curling allowance 20C of rear plate 8, curling allowance 11C of body plate 10, curling allowance 20D of rear plate 8, and curling allowance 1 of top plate 9.
The curling margins 20A of the rear plate 6 and the rear plate 8 are respectively joined by a curling process. As described above, by performing the curling process at six locations, the top plate 9, the body plate 10, and the rear plate 8 are each firmly joined. Each of these curling processes can be advantageously carried out by the apparatus and method disclosed in Japanese Patent Application Laid-open No. 55-54230, Japanese Patent Application Publication No. 55-54231 and Japanese Patent Application Publication No. 55-54221 by the same applicant.

Next, the front plate 5 and the body plate 10, which are the features of this invention.
Also, the joint structure between the front plate 5 and the top plate 9 will be explained. As is clear from FIG. 6, the front edge of the body plate 10 has a curling margin 13 as a bent portion.
A, 13B, and 13C are formed. A plurality of circular through holes 200 are formed in each of the curling margins 13A, 13B, and 13C. Similarly, a plurality of circular through holes 200 are formed in the curling margin 18 at the front edge of the top plate 9. On the other hand, as is clear from FIG. 7, which is a perspective view of the front plate 5 seen from the rear, the front plate 5 as a bent portion
A locking protrusion 201 corresponding to the hole 200 described above is formed on the peripheral edge 7a of the opening 7. The locking protrusion 201 has an elliptical shape, as is clear from FIG. 8, which is an enlarged view of the portion indicated by . The locking protrusion 201 has a protruding shape, and the protruding portion of the locking protrusion 201 is relatively larger than the through hole 200 described above.

In addition, since the joint structure between the front plate 5 and the body plate 10 is the same as the joint structure between the front plate 5 and the top plate 9, the following explanation will only refer to the joint structure between the front plate 5 and the top plate 9. explain. Therefore, the front plate 5 and the body plate 10
For the joining structure between the front plate 5 and the top plate 9, please refer to the explanation about the joining structure between the front plate 5 and the top plate 9.

As is clear from FIG. 8, the opening 7 of the front plate 5
A bent portion 27 as a curling margin is formed on the peripheral edge 7a, and a locking protrusion 201 is formed on this bent portion 27 as described above. The locking protrusion 201 can be easily formed at any time during the processing of the front plate 5 shown in FIG. 7, for example, by abutment with a mold. A bent portion 27 of the front plate 5 having the locking protrusion 201 formed in this way,
The curling margin 18 as a bending part of the top plate 9 is
As shown in the partially cutaway cross-sectional view of FIG. 10, the pieces are moved in a direction close to each other and overlapped, and then curling is performed. FIGS. 13A to 13C are diagrams showing the curling process.

Referring to FIG. 13A, the top plate is placed in the space defined by the front plate 5 and the bent part 27 (hereinafter referred to as the front plate bent part 27) provided at the opening edge 7a of the front plate. A bent portion 18 (hereinafter referred to as
A top plate bent portion 18) is fitted therein.
A hole 200 is provided in the top plate bent portion 18,
The front plate bent portion 27 is a protrusion 20 that should fit into the hole 200.
1 is provided. This protrusion 201 is the hole 200
It has dimensions larger than the diameter of. That is,
In this embodiment, it is assumed that the protrusion 201 and the hole 200 are not fitted together at this stage. This eliminates the need for the complicated work of accurately aligning the protrusion 201 and the hole 200 and fitting the protrusion 201 into the hole 200. Periphery 7 of the opening of the front plate 5
a is in contact with the mold 50 and its position is fixed. The front edge 9a of the top plate abuts against the mold 51, and its position is fixed. Then, the top plate 9 is pressed in the direction shown by the arrow X and the front plate 5 is pressed in the direction shown by the arrow Y using another mold. Then, the 13th
Referring to Figure B, the opening periphery 7 of the front plate bent portion 27
a is in contact with the mold 50 and its position is fixed, and the front edge 9a is in contact with the mold 51 and its position is fixed, so the front plate bent portion 27 is bent as shown in the figure, and the protrusion 201 fits into the hole 200 while being shaped by the wall surface of the hole 200. At this time, a part of the locking protrusion 201 fits into the hole 200, but the remaining part comes into contact with the metal surface around the hole 200 and is flattened.

FIG. 13C shows the state after this caulking work is completed, and shows a state in which a part of the locking protrusion 201 is fitted into the hole 200. A part of the locking protrusion 201 is reliably embedded in the hole 200, and the locking protrusion 201 and the hole 2
There is no gap between it and 00. the result,
Even if the caulking force is somewhat weak, the protrusion 201 will not shift in position and will not wobble. As a result, the bonding strength between the front plate and the top plate is dramatically increased.

In the joint structure shown in FIG. 11, even if the front plate 5 and the top plate 9 are pulled or pushed in either direction of the arrows (X) and (-X), the joint will not shift. Therefore, it can be seen that the bonding structure of the embodiment shown in FIG. 10 has extremely high bonding strength compared to the conventional bonding structure shown in FIG. 2.

By the way, the inventor of the present application has disclosed a joining structure consisting of a locking protrusion 201 and a hole 200 similar to the invention of the present application in Utility Application No. 58-68273. However, in the present invention, the locking protrusion 20
1 is relatively larger than the hole 200 as described above, the locking protrusion 201 and the hole 200
This has the extremely large effect of making the complicated positioning of the device even easier. For example, in the embodiment described above, as is clear from FIG.
The locking protrusion 201 is larger than the hole 200 and is formed as an elliptical protrusion as shown in FIG. The locking protrusion 2 does not need to accurately control the amount of penetration between the
At least a portion of 01 may be aligned with hole 200. If the curling process is performed in this state, only a part of the locking protrusion 201 will fit into the hole 200, as shown in FIG. Hole 20 in bent portion 18
It is pressed against the surrounding surface of 0 and is flattened. It will therefore be appreciated that the locking protrusion 201 is relatively larger than the hole 200 to obtain an effective locking structure.

In the above embodiment, the locking protrusion 201 is formed as an elliptical protrusion, but as shown in a schematic partially cutaway perspective view in FIG. 12, a rectangular locking protrusion 201 may also be used. Needless to say, it's a good thing. In addition, as long as the locking protrusion 201 is relatively larger than the hole 200 as described above, the locking protrusion 201 may be formed to protrude in any shape. However, preferably, for the circular hole 200 as in the embodiment described above, the width is smaller than the diameter of the hole 200 in a certain direction, and the width is smaller than the diameter of the hole 200 in another direction intersecting the said direction. If the locking protrusion 201 is configured to be long, the locking protrusion 20
1 and the hole 200 can be fitted more smoothly.

Effects of the Invention As described above, according to the inner box of the cooking appliance according to the present invention, the protrusion provided on one bent part has a larger dimension than the hole provided in the other bent part. This large portion is fitted into the hole while being shaped by the wall surface of the hole by caulking. Therefore, when performing the curling process to obtain the above-mentioned joining structure, a space defined by the front plate and a bent part provided at the edge of the opening of the front plate is provided at the front edge of the body. It is sufficient to simply fit the folded portion. That is, it is sufficient to roughly align the protrusions and holes, and accurate alignment between the protrusions and holes is not necessary. The operation of fitting the protrusion into the hole is performed during the caulking operation. Since the joint structure is formed through such a simple process, the inner box of the cooking appliance can be manufactured very easily.

In addition, the protrusion includes a portion having a larger dimension than the diameter of the hole, and this larger portion is fitted into the hole while being formed by the wall surface of the hole by caulking. Since the protrusion is embedded in the hole, the protrusion is reliably embedded in the hole, and no gap is created between the protrusion and the hole. Therefore, even if the caulking force is somewhat weak, the protrusions will not be misaligned and no rattling will occur. As a result, the effect of dramatically increasing the bonding strength between the front plate and the body is achieved.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing an example of a microwave oven to which this invention is applied. 2 is a perspective view schematically showing the inner box of the microwave oven shown in FIG. 1. FIG. FIG. 3 is a partially cutaway perspective view showing the joint structure of the inner box of FIG. 2 in detail. Figures 4 and 5
The figure is a partially cutaway sectional view showing a curling joint structure between a front plate and a body in an inner box of a conventional cooking appliance. FIG. 6 is a perspective view showing the process of manufacturing an embodiment of this invention. FIG. 7 is a perspective view of the front plate used in one embodiment of this invention, viewed from the rear. FIG. 8 is an enlarged perspective view of the portion shown in FIG. 7. FIG. 9 is an enlarged perspective view of the locking protrusion. Figure 10 and 1
FIG. 1 is a partially cutaway sectional view for explaining the joining structure of an embodiment of this invention. Figure 12 shows
It is a schematic perspective view which shows another example of a locking protrusion. FIGS. 13A to 13C are cross-sectional views of the curling process. In the figure, 4 is the inner box of the cooking appliance, 5 is the front plate,
6 is a body, 7 is an opening, 7a is an opening periphery, 8 is a rear plate, 9a, 10a are front edges of the body, 9b, 10
b is the rear edge of the body, 27 is a bent portion on the front edge of the opening, 18 is a bent portion on the front edge of the top plate, 200 is a hole, 2
01 indicates a locking protrusion.

Claims (1)

[Claims for Utility Model Registration] A front plate having an opening, a cylindrical body, a bent portion provided around the opening of the front plate, and a folded portion provided at the front edge of the body. a bent part, the one bent part is provided with a hole, the other bent part is provided with a protrusion that fits into the hole, and the one bent part is provided with a projection that fits into the hole; and the other bent portion are joined by caulking, the protrusion includes a portion having a larger dimension than the diameter of the hole, and the protrusion has the larger dimension. An inner box for a cooking appliance, characterized in that the part of the inner box fits into the hole while being formed by the wall surface of the hole by the caulking operation.