Curved panel

A curved panel including a panel body and a pair of reinforcing members fixed to the panel body and arranged so that a planar restorative force of the panel body is balanced by a resilient force of each of the pair of reinforcing members so as to keep the panel body at a predetermined curvature. The panel body is made of resiliently deformable material including a face portion at (a) each of a first pair of opposite sides to which a deformable bent portion is attached which allows the face portion of the panel body to be curved to the predetermined curvature and at (b) each of a second pair of opposite sides to which a reinforcing bent portion is attached which keeps the second pair of opposite sides linear. The reinforcing members have a curvature greater than the predetermined curvature and are fixed to the deformable bent portions of the panel body.

FIELD OF THE ART 
This invention relates to a curved panel so designed as to be easily formed 
into a desired curvature by curving the panel body and fixing reinforcing 
members to the curved panel body. 
BACKGROUND ART 
The recent tendency in designing furniture and architecture is that curved 
surfaces are positively employed in various parts from the viewpoint of 
design and function. Works produced from such a viewpoint are for example 
desks and tables having curved front panels, doors and partition walls the 
whole face plates of which are curved, arched ceilings having curved 
interior surfaces, and pillars circumferentially covered with a decorative 
hollow cylindrical member. 
The front panels, face plates, interior surfaces and decorative members of 
the above-mentioned types are usually made of steel plate by pressing. For 
pressing such material those dies which conform to the desired shapes of 
the products are required. If the abovementioned relatively large-sized 
panel is to be formed by this method, the die must be as large as the 
panel to be formed and becomes expensive. As many dies as there are 
various kinds of products are required, with resulting increase in the 
manufacturing cost. Large-sized dies would necessarily require a 
large-sized machine. Since pressing utilizes plastic deformation, a strain 
is left in the pressed part after the exterior force has been removed. 
Therefore, the larger the curved surface is, the higher degree of 
precision is required for pressing. Otherwise, an unnecessarily large 
strain would be left in the pressed workpiece, so that it would become 
difficult to produce a good curved surface in the finished product. 
In view of the above problems, this invention has been made, its object 
being to provide a curved panel which has various advantages such that it 
is possible to reduce the size of the apparatus, easily produce products 
of various specifications, reduce the manufacturing cost and improve the 
quality of the finished curved surface. 
DISCLOSURE OF THE INVENTION 
To accomplish the above object the invention has the following 
construction. 
The curved panel of the invention comprises a panel body and a pair of 
reinforcing members and is so arranged that the resilient force of the 
panel body to be restored to a flat condition balances the resilient force 
of the reinforcing members so as to keep the panel body at a predetermined 
curvature. The curved panel is characterized by that the panel body is a 
flat member made of resiliently deformable material and comprising a face 
portion at each of the two opposite sides of which a deformable bent 
portion is provided which allows the face portion to be curved and at each 
of the other two opposite sides of which a reinforcing bent portion is 
provided which keeps the other two opposite sides of the face portion 
linear; and that the reinforcing members have a curvature greater than the 
above-mentioned predetermined curvature, and are fixed to the deformable 
bent portions of the panel body having been forcedly curved. 
The curvature of the panel body need not necessarily be uniform over the 
whole face portion of the panel body. In particular, if the face portion 
is divided into minute sections along the length of the deformable bent 
portions, each of the sections may have a different curvature from those 
of the other sections provided that the reinforcing members have a greater 
curvature in each corresponding section. Some of the sections of the panel 
body may be plane. The description that the curvature is relatively great 
means that the radius of curvature is smaller except in linear sections. 
In the panel body of the above construction, with the two opposite sides 
thereof provided with the reinforcing bent portions being kept linear, the 
other two opposite sides thereof provided with the deformable bent 
portions are curved by application of an artificial force thereto along 
the curve of the reinforcing members, and the reinforcing members are 
fixed to the curved bent portions, and then the artificial force is 
removed, whereupon the resilient force of the panel body to be restored to 
a plane counteracts the resilient force of the reinforcing members to be 
restored to their original curvature in opposite directions to each other, 
so that they balance to keep the panel body at a desired curvature. 
The processing steps required for the curved panel are to form the 
deformable bent portions and the reinforcing bent portions at each pair of 
sides of the panel and to form the reinforcing members. To make the panel 
it suffices to work an elongated member and it is not necessary to work 
the whole of a plate. Therefore, when a large panel is to be made, a 
smaller machine suffices as compared with pressing the whole of a plate, 
with resulting reduction of the cost involved. If products of various 
specifications are to be made, the curvature of the reinforcing members 
has only to be changed without increasing the cost involved. Since in 
accordance with this method the panel is curved within the range of its 
elasticity, the force to restore the panel to its plane condition acts to 
remove strain uniformly all over the face portion of the panel, so that 
the panel has a curved surface of very high quality. 
The invention includes the following embodiments. The deformable bent 
portion may be a flange provided with cuts longitudinally spaced apart, or 
an L-shaped portion provided with cuts longitudinally spaced apart, or a 
portion shaped like the letter of and provided with cuts longitudinally 
spaced apart. The reinforcing member may be a reinforcing plate made by 
bending a steel to an L-shape in cross section, a reinforcing channel 
member made by bending a steel plate to the letter of in cross section, 
a reinforcing pipe made by bending a steel plate, or a member made of a 
shape memory alloy which is restored to a greater curvature than a desired 
curved surface when heated above the normal temperature.

BEST MODES OF EMBODYING THE INVENTION 
One embodiment of the invention will be described below with reference to 
the drawing. 
As shown in FIG. 1, the curved panel A comprises a curved panel body 1 and 
a pair of reinforcing plates 2 fixed to the opposite sides or edge of the 
panel body 1 so that the resilient force of the panel body 1 to be 
restored to its flat or planar condition is balanced by the resilient 
force of the reinforcing plates 2 to be restored to their original 
curvature shape in the opposite direction thereby to keep the panel body 1 
in a desired curved condition. 
In particular, the panel body 1 is a resiliently deformable thin steel 
plate, which is provided at its two opposite sides 1a, 1a with a 
deformable bent portion 12 having a plurality of sawtooth cuts 11, and at 
the other two opposite sides 1b, 1b with a reinforcing bent portion 13 
without such sawtooth cuts formed therein. To form the bent portions 12 
and 13, a steel plate is stamped so that along the four sides of a face 
plate portion 1c bendable marginal portions 12a and 13a are left, which 
are then deformed like the letter L in cross section by roll forming. The 
bent marginal portions 12 and 13 are connected at the four corners by 
welding. In the stamping process the sawtooth cuts 11 are formed in the 
bendable marginal portions 12a. The cuts 11 are V-shaped and have a bottom 
not pointed but rounded. Due to the arrangement, when an exterior force 
acts on the face portion 1c of the panel body 1, the face portion 1c is 
comparatively easily curved along the deformable bent portions 12, but 
hardly along the reinforcing bent portions 13. 
As shown in FIGS. 1 and 4, the reinforcing members 2 are made of a thick 
steel plate cut by laser into an arcuate member having a curvature 
slightly greater than that of the curved surface of the panel to be 
manufactured. The reinforcing members have a cross-sectional shape 
substantially corresponding to that of the space defined inside the 
deformable bent portions 12 and a length substantially equal to that of 
the bent portions 12. 
With the opposite sides or edges of the panel body 1 provided with the 
reinforcing bent portions 13 being held straight, an artificial force is 
applied to the two opposite sides or edges of the panel body 1 provided 
with the deformable bent portions 12 so as to curve it into conformity 
with the curvature of the reinforcing members 2 as shown in FIG. 4, and 
the elongatedly curved reinforcing members 2 are placed inside the upper 
and lower bent portions 12 of the curved panel body 1 and secured therein 
by spot welding as shown in FIGS. 5 and 6. Then the artificial force is 
removed to complete the assembly. Under the conditon, as shown in FIG. 7, 
the resilient force F1 of the panel body 1 to be restored to the flat or 
planar condition 1' shown in phantom line counteracts the resilient force 
F2 of the reinforcing member 2 to be restored to the original curvature, 
greater curvature 2' shown in phantom line 1', so that the panel body 1 
and the reinforcing member 2 take the intended or predetermined curvature 
at the position shown in solid line (which is a position 2" of lesser 
curvature for reinforcing members 2) where the two forces balance. 
Since the curved panel A is of the above-mentioned construction, the 
processing steps required of making the illustrated embodiment is the roll 
forming step to form the deformable bent portions 12 and the reinforcing 
bent portions 13 at the two opposite sides or edges 1a, 1a and 1b, 1b, 
resepctively, and the cutting step by laser to form the reinforcing plates 
2. Thus it is possible to complete production of the panel A by merely 
processing an elongated member, so that when a large-sized panel is to be 
made, a smaller machine tool suffices than if the whole surface of a plate 
is machined by a press, with resulting reduction of the manufacturing 
cost. Moreover, since laser cutting is generally conducted by numerical 
control, it is possible to change the curvature of the reinforcing plates 
by merely changing the set numerical values, thereby to easily produce 
curved panels of different specifications. In addition, since according to 
the method the face portion 1c of the panel body 1 is curved within the 
range of its elasticity, the force to restore the curved face portion 1c 
to its flat condition acts to remove strain in each and every part 
thereof, thereby to produce a good curved surface at the portion where it 
balances the reinforcing plates 2. 
If the curved panel A is used as the front panel of a conference table B as 
shown in FIG. 8, it is possible to make tables of different radii, without 
increasing the panel size and the number of kinds of panels and 
consequently the manufacturing cost. The improved quality of the curved 
surface of the front panel gives a good appearance to the whole table. 
The invention is not limited to the above described embodiment. In the 
above embodiment, the bent portion 12 is shaped like the letter of L. A 
flange-like bent portion 112 as shown in FIGS. 9, 10, 11, 12, or a bent 
portion 212 shaped like the letter of as shown in FIG. 16 may also be 
used. In the above embodiments, the reinforcing members 2 are made of a 
thick steel plate cut to the required shape. If can also be a reinforcing 
angle 102 made of a steel plate bent to an L-shape in transverse section 
as shown in FIGS. 10, 13 and 16, or a reinforcing channel-like member 202 
made of a steel plate bent to a transverse shape like the letter of as 
shown in FIGS. 11 and 14, or a reinforcing pipe 302 made by bending a 
steel plate to the shape as shown in FIGS. 12 and 15. These members may be 
fixed to the panel body by means of spot welding. Alternatively, it is 
advantageous to provide the deformable bent portions 12 with a claw 112 as 
shown in FIG. 13 or the reinforcing angle 102 with a claw 102a as shown in 
FIG. 16 for preventing the reinforcing member or the angle from falling 
off the panel body. The reinforcing member may also be made of a shape 
memory alloy which is restored to a greater curvature than a desired 
curvature when heated to a higher temperature than the normal temperature. 
The steel plate may be a steel plate covered by vinyl chloride film, a 
coated steel plate, a stainless steel plate, or a resiliently deformable 
synthetic resin plate. Besides the above-mentioned conference table, the 
curved panel may also be used in a desk whose front panel has a curved 
surface, a door or a partition wall whose whole surface is curved, an 
arched ceiling whose inner surface is curved, or a pillar whose outer 
circumference is covered with a hollow cylindrical decorative member. 
Several embodiments having been described, the invention is not restricted 
to them but there may be various modifications without departing from the 
principle of the invention. 
POSSIBLE APPLICATIONS IN INDUSTRY 
As mentioned above, the curved panel of the invention is useful in 
application to a desk or a table whose front panel is curved, a door or a 
partition wall whose whole surface is curved, an arched ceiling whose 
inner surface is curved, or a pillar whose outer circumference is covered 
with a hollow cylindrical decorative member.