Manufacturing container or tube from paper; or other manufacturi – Bending
Reexamination Certificate
2000-12-18
2003-12-23
Kim, Eugene (Department: 3721)
Manufacturing container or tube from paper; or other manufacturi
Bending
C493S397000, C493S447000
Reexamination Certificate
active
06666808
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a sheet and a blade for shaping a sheet folding portion, and more particularly a sheet foldable along a folding portion, and a blade for shaping the folding portion on the sheet, which are applicable, for example to manufacturing of a clear case ( a box formed by folding a plastic sheet).
BACKGROUND OF THE INVENTION
There have been known sheets adapted to be folded, such as one described in the Japanese Unexamined Utility Model Application Publication No. Sho-63-91455. The sheet described in the cited publication includes a recessed groove disposed orthogonal to a sheet folding direction, and a folding portion including recesses and protrusions formed on the bottom portion of the recessed groove in the lengthwise direction (Prior Art 1).
Unlike the recesses and protrusions, it is also known the sheet with holes intermittently formed on the bottom portion of the recessed groove in the lengthwise direction thereof (Japanese Unexamined Patent Application Publication No. Sho-64-40317, Prior Art 2).
The sheets of the Prior Arts 1 and 2 each are foldable precisely along the recessed groove, and possess capabilities of maintaining the strength and preventing the breakage of the sheet through shallow portions of the recessed groove, while exhibiting foldability through deep portions or intermittently formed holes of the recessed groove, thereby rendering the sheet foldable.
As a sheet described in the Unexamined Japanese Patent Application Publication No. Hei-1-150520, it is also know a sheet with reinforcing ribs shaped between the recesses and protrusions on the bottom portion of the recessed-groove in the lengthwise direction (Prior Art 3).
However, any conventional sheets as described above pose problems that they have the folding portion of less strength when a deeply recessed groove is provided or the protrusions in the recessed groove are shaped with smaller dimension, and on the contrary, they have less foldability when the protrusions are shaped with larger dimension in order to maintain the strength of the sheet.
That is, taking the Prior Art 3 for example, the reinforcing ribs are shaped perpendicular to the recessed groove (in the folding direction), so that the reinforcing ribs abut against each other when the sheet is folded towards the side thereof with the recessed groove, thereby preventing the sheet from folding. This poses a problem of deteriorating the foldability of the sheet. In addition, the sheet with the smaller reinforcing ribs shaped for assuring the foldability also poses a problem of lacking the sheet strength.
On the other hand, when the sheet is folded towards the side thereof without the recessed groove, the reinforcing ribs are subjected to the force applied in the sheet tearing direction, so that the reinforcing ribs may be broken or similar events may occur. When the larger reinforcing ribs are shaped to prevent such a breakage, it also poses a problem of deteriorating the foldability of the sheet.
SUMMARY OF THE INVENTION
The present invention has been conceived to solve the above problems. It is an object of the present invention to provide a sheet that is capable of simultaneously satisfying the demands on the foldability and the strength of the sheet.
The present invention has been conceived to solve the above problems by providing a sheet, which includes a sheet body
10
such as a plastic sheet with a folding portion
12
provided perpendicular to the folding direction X, which is characterized by that the folding portion
12
includes a large number of recesses
14
and remnants
16
between the recesses
14
shaped on the sheet body
10
, boundary lines
18
defined between the recesses
14
and the remnants
16
each are tilted at acute angle with respect to the folding portion-forming direction Y and towards the same side as that of an opposing one of the boundary lines
18
with a corresponding remnant
16
therebetween.
According to the sheet of the present invention having the above arrangement, when the sheet body
10
is folded along the folding portion
12
in the folding direction X, the remnants
16
each having the corresponding opposite boundary lines
18
tilted towards the same side are brought into a twisted state, so that the remnants
16
are unlikely to abut each other. In addition, even if the force is effected on the remnants
16
in the sheet tearing direction, the tilted boundary lines
18
of the remnants
16
can disperse the tearing direction oriented force, thereby preventing the breakage of the remnants
16
.
Thus, the sheet of the above arrangement is advantageous in the fact that it can simultaneously satisfy the demands on the foldability and the sheet strength.
According to the sheet of the present invention, all the boundary lines
18
between the recesses
14
and the remnants
16
are preferably tilted in such a manner as to be aligned parallel to each other. This advantageously enables the folding portion
12
to be easily shaped.
The boundary lines
18
between the recesses
14
and the remnants
16
each are preferably tilted at an angle of 5 degrees or more with respect to the folding portion-forming direction Y, which advantageously enables the folding portion
12
to be easily shaped. That is, if the tilting angle is less than 5 degrees, the shaping of the folding portion
12
of the sheet body
10
involves a troublesome work. In addition, when the folding portion
12
is shaped such as by the pressure effected by a blade for shaping the sheet folding portion, the blade may decrease the strength of its own. To solve these problems, the tilting angle is more preferably set to 10 degrees or more.
On the other hand, the tilting angle is preferably set to 60 degrees or less, thereby enabling the sheet to sufficiently exhibit its strength. That is, when the tilting angle is set to more than 60 degrees, it is unlikely to smoothly disperse the tearing direction oriented force caused on the remnants
16
, with the result that the breakage of the remnants
16
cannot reliably be prevented. To reliably prevent such a breakage, the tilting angle is more preferably set to 30 degrees or less.
Each recess
14
has the length L
1
in the folding portion-forming direction Y, which is preferably set to 0.5 times or more the sheet thickness H. When the folding portion
12
with the tilting angle of less than 0.5 times is shaped by the blade, the blade is unlikely to assure a sufficient strength. As a result, the blade may have a nicked edge during the mass production of the sheet. On the contrary, the tilting angle of 0.5 times or more renders the sheet suitable for the mass production.
The length L
1
of each recess
14
in the folding portion-forming direction Y is preferably set to 100 times or less the sheet thickness H. When the folding portion with the recesses
14
each having the length L
1
of 100 times or more is applied to an assembly case or the like, corner portions thereof are largely deformed, posing problems that the assembly case cannot be firmly assembled, and hence the folding portion may be broken. On the contrary, the length L
1
of 100 times or less is advantageous that the folding portion
12
is prevented from being broken.
Further, each remnant
16
has the length L
2
in the folding portion-forming direction Y, which is preferably set to 0.3 times or more the sheet thickness H. When the length L
2
of the remnant
16
is set to less than 0.3 times, the strength is extremely reduced, with the result that the sheet may be torn apart at the folding portion
12
. On the contrary, the length L
2
of 0.3 times or more is advantageous that the sheet is prevented from being torn apart at the folding portion
12
.
Still further, the length L
2
of each remnant
16
in the folding portion-forming direction Y is preferably set to three times or less the sheet thickness H. The remnants
16
each having the length L
2
set to more than three times tend to harden, allowing the folding portion
12
to be easily broken. On the contrary, the length L
2
of 3 tim
Kawata Haruyoshi
Omori Shoichi
Fuji Seal Inc.
Jordan and Hamburg LLP
Kim Eugene
LandOfFree
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