Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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The present invention relates to an annular core for
use in supporting rolls of flat strips of material such as
paper, plastics, adhesive tape or the like rolls. The core is
particularly suitable for but not limited to the use in paper
rolls used in adding machines, cash registers or the like.
The cores for paper or the like flat strip rolls are
mainly produced from paper by lamination. The paper cores suffer
from drawback of a relatively low strength which makes the cores
subject to mechanical damage both prior to and following the
winding of paper or the like thereon, with the resulting
inaccuracies of the inside diameter of such cores which often
renders the wound roll useless due to a relatively close toler-
ances between the inside diameter of the core and the outside
diameter of the roll supporting pin or shaft used in the particular
machine. A typdcal example of such cores is disclosed in Canadian
patent 679,952 issued February 11, 1964 to Wicklund, or Canadian
patent 463,345 issued February 21, 1950 to Blanchet. Paper cores
of this type frequently require the use of special end caps to
protect the ends of the core from mechanical damage, the end
caps presenting additional manufact~ring costs. Another
problem associated with the use of paper cores is caused by
dimensional changes of same caused by variations in air humidity
as the mass of the core tends to expand in a more humid environment
thus often rendering the inside diameter of the core too small
and no longer rotatable about its supporting shaft or pin in the
cash resister or the like. In order to avoid the latter draw-
back, it has been proposed to manufacture e.g. textile bobbins
from a plastics material (Canadian patent 352,838 issued September
3, 1935 to Dreyfus~. However, the known plastics cores have pro-
ven to be relatively expensive as they are mainly injection
moulded products of a predetermined length suitable for only one
width of the paper roll. Moreover, even though the prob~em due
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to the variations in air humidity are a~oided, the problems of
relatively low overall strength and resistance to damage are
still present in the ~nown plastic cores. The kno~n plastic
cores are relatively massive and require a relatively high volume
of thermoplastic material, which has nowadays become a relatively
expensive commodity. Accordingly, virtually all of the known
types of plastics cores have been abandoned and the ald known
paper rolls re-introduced in the market.
It is an object of the present invention to overcome
the above drawbacks by using a tubular core in the form of a
plastics tube which would not only possess the above advantages
of plastics cores but would also be relatively inexpensive to
produce, would have a light weight and would be dimensionally
stable both prior to and after the winding of a paper or the like
strip forming the roll. Another object of the present invention
is to produce a core which can be manufactured from a relatively
long tube of indeterminate length by slicing the tube into a
predetermined length to produce the core. The present invention
is particularly concerned with the solving of the problem of
produoing a tube which, on the one hand, is dimensionally stable
- and, on the other hand, is relatively easy to slice into said
individual cores, without distorting the shape of the tubular
structure.
According to the invention, a tube is pr~vided for
producing, by slicing, a plurality of annular cores for use in
supporting rolls of flat strips of material such as paper, plastics,
adhesive tape or the like. The tube is a unitary, extrusion
moulded, thin-walled tubular structure comprising a radially
outside, generally cylindric wall, a radially inside, generally
cylindric wall concentric with and radially spaced from said
outside wall, and a plurality of thin-walled spacing ribs unitary
with both cylindric walls, said spacing ribs extending generally
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parallel with axial elongation of the core and being generally
equidistantl~ spaced from each other about said annular space.
Thus, the present invention facilitates the production of an
annular core for use in supportingrolls such as paper rolls or
the like for use in adding machines, cash registers, etc., the
structural features of the core being identical tothose of the
above mentioned tube. The ribs are preferably of the same
-thicXness as the walls and extend in a generally
radial direction relative to the concentric tubular walls.
The tube according to the present invention ean easily
be sliced or cut into a plurality of cores, mainly due to its
relatively low cross-cectional mass which is achieved by a thin-
walled overall structure, the term "thin-walled" in this context
meaning that the thickness of walls of the tu~e, be it the outer
or the inner cylindric wall or the ribs, as will be described
hereinafter, is in the size as described. It has been found
that the radial arrangement of the ribs is preferable as it not
only su~fices from the standpoint of strength but also requires
less plastics material and thus reduces the overall weight of
the core or of the tube. Generally, the thickness of the core
and walls of ribs may be well below 1 millimeter, with the out-
side diameter of the core varying in dependence on the proposed
use.
The invention will now be described by way of examples
with reference to the accompanying drawings in which
Figure 1 is a perspective view of a paper:roll wound
on a core of the present invention;
Figure 2 is a side view partly in section, of a tube
from which the cores of the present invention can be produced; and
Figure 3 is an end Yiew of the tube of figure 2.
In the drawings, the corresponding parts of the tube
in figures 2 and 3 are referred with the same reference numerals
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as the portions of the sliced core sho~n in figure l.
The embodiment shown in figure 1 is a unitary core
1 from nylon Ctrademark~ and produced by extrusion moulaing of
a tube l' ~figures 2 and 3~ of an indeterminate length and by
subsequent cutting of same to produce the required length of
the core 1. The core l, as well a~ the tube l' r consists of a
thin-walled inner tube or cylindric member 4 f~m whos-e outside
surface protrudes a plurality of radial ribs 6 whose outside
ends are coincident with the inside ~urface of an outer cylindric
member 2. The core is shown in use with a roll 8 of a paper,
figure l showing such roll ready for application in a cash reg-
ister.
The shown embodiment of the core has a 25 mm outside
diameter, 18 mm inside diameter, the thickness of the cylindric
walls being about 0.5 mm and that of the ribs amounting to
about 0.9 mm. It is to be appreciated, however, that the
dimensions as outlined above refer to one embodiment only and
may vary depending on the in~ended use of the core. Thus,
another useful embodiment has the size of about 22 mm outside
diameter, 12 mm inside diameter, with the thickness of both the
cylindric walls and the ribs being about 0.3 mm. The above
goneral proportions have been found as an optimum ~rom the stand_
point of a compromise dictated, on the one hand,by the req_
uirement of dimensional stability and,on the other hand, by the
required volume of the plastics material necessary for producing
the tube. There are 12 equidistantly spaced radial ribs in both
embodiments, even though it is to be appreciated that the number
of the ribs may vary. The radial arrangement of the ribs is
preferred as it was found that it satisfies the requirement of
strength of the overall structure even with an extremely thin
rib, the thin ri~ in turn being of advantage from the stand-
point of cost of production and from the standpoint of producing
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the cores by cutting or slicing the tube.
Those skilled in the art will readily conceive further
embodiments of the present invention differing from the embodiments
referred to above but still falling within the scope of the
present invention as defined in the accompanying claims.
