Metal deforming – By relatively movable offset tool-faces – With tool motion in fixed path
Reexamination Certificate
2002-02-22
2004-01-06
Jones, David (Department: 3725)
Metal deforming
By relatively movable offset tool-faces
With tool motion in fixed path
C072S396000, C072S387000
Reexamination Certificate
active
06672127
ABSTRACT:
TECHNICAL FIELD
The present invention relates to the apparatus for bending metal plates by the use of special metal molds. Particularly, this apparatus is characterized in that it is provided with the rotary control function, cushion materials, etc. Such apparatus is used as a bender for bending metal plates (press brake), oil pressure press, air pressure press, mechanical press, etc.
In addition, the present invention relates to the apparatus for bending metal plates in U-shape by the use of two (2) lower bar molds semicircular in section. This apparatus is characterized in that the tip-rounded upper mold is used, the lower bar molds are provided with rotary control function and that the odd part/parts of lower bar molds are cut off to form an odd pressing part/parts. Such apparatus is used as a bender for bending metal plates (press brake), oil pressure press, air pressure press, mechanical press, etc. in a U shape, such metal plates bent being used for buildings, kitchens, rail-guides, cooling fans, oval pipes, etc.
BACKGROUND ART
Regarding the apparatus for bending metal plates by the use of metal molds, such as, for an example, “a bender”, there have been conventionally used the lower plane molds provided with a groove thereon and the upper punching mold. The metal plate is placed on the groove on the lower plane molds. Then, the metal plate is pressed into the groove of the lower mold and thereby bent.
However, there are disadvantages in the above apparatus. Since the groove between the lower plane molds is limited in size and shape, several scores of the lower plane molds provided with the different size and shape of grooves are required to be prepared for taking care of the different thickness of the metal plate to be bent and the different bending degree required. This causes a larger cost in equipment. Not only that, but a space is required for storing such number of the lower plane molds. This is a problem in terms of space economy. Furthermore, the lower mold is required to be changed, whenever necessary, depending upon the purpose for which it is used. Thus, the above apparatus is labor-consuming and lowers an operational efficiency.
Particularly, when the thin metal plate is bent, the acute bending accuracy desired is not likely to be obtained because the tip part of the groove is too wide. When the thick metal plate is bent, scratches are liable to be formed on the surface of the metal plate, because the groove gets tight in its tip part.
In addition, the pressure of the upper mold is rectangularly, by way of the metal plate, imposed on the groove between the lower plane molds. As there is no pressure relief, an excessive pressure causes the friction between the surface of the metal plate and the groove surface of the lower mold. Thus, there are formed scratches on the surface of the metal plate. Such scratches produce the inferior appearance on the products made of the metal plate bent in such manner. This is another disadvantage.
Furthermore, as the pressure of the upper mold is linearly concentrated on the surface of the metal plate with the groove between the lower molds at the supporting point, the physical texture of the metal plate is damaged and deteriorated. Thus, cracks are produced therein. The physical strength thereof is lowered. When, particularly, the shoulder R of the metal plate is small, this defect is conspicuously developed.
Furthermore, the stroke of the upper mold reaches the lower dead point and bends the metal plate. Because of this mechanism, the strong pressure of the upper mold is directly transferred to the groove between the lower molds. Thus, the impact thereof is large. Scratches and damages are caused on the groove surface between the lower plane molds. The groove between the lower mold tends to be abraded and worn out. These are the disadvantages of the conventional molds.
Furthermore, the metal plate is placed on the groove between the lower plane molds and then bent by pressing it down by the upper mold. When the tip part of the metal plate is bent or when the bending length is too short, the metal plate tends to get out of place. Even when the tip part of the metal plate can be bent, the bending accuracy thereof tends to be insufficient or unsatisfactory.
Then, we have made a considerable study of the conventional apparatus for bending metal plates. As a result, there has been developed the apparatus for bending metal plates involving the use of entirely new special lower molds. The patent application has been filed for it (Application No. Hei-10-373221). Thus, there have been overcome the aforementioned problems and disadvantages of the conventional apparatus for bending metal plates.
Referring to the metal bending apparatus involving the use of the special lower molds, the metal mold comprises the ordinary upper punch mold
1
and two (2) lower bar molds
2
a
and
2
b
semicircular in section having metal contact surfaces
3
a
and
3
b
on their surfaces, as shown in FIG.
1
. Further, the reverse surfaces
5
a
and
5
b
of these two (2) lower bar molds are placed so as to rotate slidably, as shown in
FIG. 2
, on the two (2) concave surfaces, having the groove
7
in between, formed on the support
4
.
Then, referring to the metal plate
8
bending mechanism, the metal plate
8
is placed on the metal contact surfaces
3
a
and
3
b
of two (2) lower bar molds
2
a
and
2
b.
As shown in
FIG. 3
, the metal plate
8
is downwardly pressed by the upper mold
1
. Simultaneously, the metal contact surfaces
3
a
and
3
b
of two (2) lower bar molds
2
a
and
2
b
are caused to rotate inwardly and the metal plate
8
is bent in V-shape.
As mentioned above, the metal plate bending apparatus involving the use of the special lower mold is unlike the conventional plane lower molds. Thus, it is not required to use scores of plane lower molds different in size and shape, depending upon the thickness of metal plates to be bent. It is provided with such function as to bend metal plates to an optional degree by the use of lower molds comprising one or a few sets of lower bar molds
2
a
and
2
b.
Because of this function, facility cost is lowered and a storing place is made smaller. There is no need to change lower molds. Thus, operational efficiency, etc. is improved. These are advantages thereof.
Further, when bending the metal plate
8
, the downward pressure of the upper mold
1
is reduced. Thereby, the downward pressure of the upper mold
1
is caused to run off by way of the metal plate
8
. Thus, there would be produced no scratches on metal plates
8
to be caused by the friction of the metal plate
8
against the lower bar molds
2
a
and
2
b.
Thus, the metal
8
has a good outer appearance.
However, when bending the thick metal plate
8
by the downward pressure of the upper mold
1
, the metal contact surfaces
3
a
and
3
b
tends to run off the metal plate
8
, probably because the lower bar molds
2
a
and
2
b
are rotated too smoothly. As shown in
FIG. 4
, while the bending angle of the metal plate
8
remains insufficient, the metal plate
8
separates from the metal contact surfaces
3
a
and
3
b.
The bent part of the metal plate
8
gets into the groove. The bending angle (R) of the metal plate
8
comes to be insufficient and the desired angle is not satisfactorily obtained. Thus, it is not bent neatly and the bending accuracy is lowered. These are disadvantages of the conventional apparatus.
Furthermore, when attempting to bend the metal plate
8
at an acute angle of less than 90° by the aforementioned metal plate bending apparatus, the adjacent parts on the metal contact surfaces of two (2) lower bar molds tend to get apart from each other, as shown in FIG.
4
. Thus, the bending angle of metal plate gets loose. Therefore, it was difficult to bend the metal plate
8
at an acute angle of less than 90°.
In addition, when attempting to bend the metal plate
8
by the aforementioned metal plate bending apparatus, the metal plate
8
is pressed on the metal contact surfaces
3
a
and
3
b
of the lower ba
Jones David
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Yuugenkaisha Taigaa Koosan
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