Note: Descriptions are shown in the official language in which they were submitted.
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Hub for information media
Field of the invention
Hub for wound-up information media in strip or tape form the
width of the outer winding area of the hub substantially
corresponding to the width of the medium to be wound up, the hub
having a central bore and driving cut-outs on its inner
circumference and comprising an outer ring and an inner ring
which are connected to each other.
Background of the invention
Once the magnetic coating has been produced on a flexible base in
tape form, information media, for example magnetic tapes, are cut
to the width required for use and are wound onto flanged reels or
flangeless hubs in a length of up to several thousand meters. For
this purpose, the hub is fitted with its central bore onto the
drive spindle of a winding machine and the information medium is
wound up at high speed and under a appropriately adapted winding
pressure. In general, to save on cost and weight, the hubs have
between the outer winding area and the inner circumference areas
of restricted cross section, radially running reinforcing ribs
being provided to increase the stability in this zone where the
material is thinner. An example of such a hub is mentioned in
DE-U 77 22 919. A stackable hub, on which the tape rolls, stacked
one on top of the other, are secured against twisting and
consequently against damage, is known from DE 24 48 853.
During winding of the information media onto said hubs as well as
during rewinding, such high tensions in the tape may occur that
the winding pressure causes the hub bore to be constricted, as a
result of which the hubs can no longer be fitted onto the drive
spindle of the winding apparatus or cannot be pulled off it . To
counter this problem, it is known to produce the hubs from glass
fiber reinforced plastic and, if appropriate, to dispense with
the thinning of the material mentioned; in addition, hubs of
metal are in use. However, for reasons of weight and cost, these
solutions have considerable disadvantages.
To avoid the constriction of the hub bore, the already mentioned
Utility Model 77 22 919 discloses a radially running threading
slit, which is constricted during winding and thereby takes up
the winding stress. US 3 632 053 discloses a flanged reel, the
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hub of which has the generic properties mentioned at the
beginning and on which, in addition, flexible intermediate
elements are respectively provided between hub and flange in
order to avoid transmitting the compression to the flanges.
However, as the description reveals, this known hub also requires
glass fiber reinforced polystyrene or metal as the material for
the hub. It can also be read in the description of EP-A-375 322
of the same applicant that, in spite of the flexible intermediate
elements, the inside diameter of the hub is still to much
compressed. In the latter document, to avoid this compression it
is proposed to provide between outer and inner ring a number of
obliquely running ribs, with a constriction in thickness over
their lengths which have the consequence of twisting the outer
ring against the inner zing. US 4 052 020 discloses a reel for a
computer tape, on which the outer winding area in this way to
absorb the stress occurring during winding.
French-A-22 33 675 discloses in a tape cassette a tape reel which
has a double Y-shaped cross-section and with elastically
deformable arms of curved shape between the inner and outer rings
of said reel. Those deformable arms serve to facilitate the
introduction of the drive axes into the drive openings when these
are being engaged by the drive axes of the apparatus. There is no
task of tape winding problems in general.
Setting out from the prior art mentioned above, it is an object
of the present invention to provide a hub of the generic type
mentioned at the beginning which does not have the disadvantages
°f the prior art, which is furthermore made of plastic and is to
do without reinforcing additives, for example glass fibers or
glass beads, because this presents recycling problems. Moreover,
it is a further object of the present invention that dishing of
the tape roll does not occur when a number of hubs bearing rolls
of tape, known as pancakes, are stacked one on top of the other,
and that such a stack of pancakes does not present any problems
during transport and storage.
Summary of the invention
We have found that this object if achieved with hub for wound-up
information media in strip or tape form, the width of the outer
winding area of the hub substantially corresponding to the width
of the medium to be wound up, the hub having a central bore and
driving cut-outs on its inner circumference and comprising an
outer ring and an inner ring which are connected to each other by
flexibly deformable intermediate elements extending in radial and
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circumferential directions and preventing any relative movement
of the outer ring to the inner ring in its circumferential
direction, the hub with the medium wound thereon having a
compression ratio of the compressed diameter of the inner ring to
the compressed diameter of the outer ring of less than 1:4.
Another embodiment of the invention is a hub for wound-up
information media in strip or tape form, wherein the flexibly
deformable intermediate elements are formed as residual portions
between openings which are arranged in a sequence and evenly
distributed over the circumference of the hub.
A further embodiment of the invention is a flangeless stackable
hub for wound-up information media in tape form, the width of the
winding area of the hub substantial corresponding to the width of
the information medium to be wound up, the hub having a central
bore as well as driving cut-outs on its inner circumference and
comprising an outer ring and an inner ring, which are connected
to one another by flexibly deformable intermediate elements
extending in radial and circumferential directions but preventing
any relative movement at the outer ring to the inner ring in its
circumferential directions, wherein a plurality of concentric
annular notches are provided between outer circumference and
Inner circumference, the notches being offset with respect to one
another in the radial direction in a meandering form.
Further details of the invention and expedient embodiments are
contained in the subclaims, the drawings and the description.
Short description of the invention
The invention will now be explained in further detail with
reference to the drawings, in which:
Figure 1 shows a plan view of a first embodiment of the hub
according to the invention
Figure 2 shows a cross section through a hub according to Figure 1
along the line II/II
Figures show plan views of further preferred designs of
3 19 the hub according to the invention with flexible
elements.
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,,_ 4
Preferred embodiments of the invention
A feature of the embodiment according to Figures 1 and 2 is that
the outer ring 2 of the hub comprising two concentric rings has a
double-T structure, which can be seen in cross-section, and that
annular flexible intermediate elements 4 are arranged evenly
distributed in the circumferential direction between the outer
ring 2 and the inner ring 3. By the combination of the double-T
profile and said flexible intermediate elements 4, a transmission
of the compression from the outer ring to the inner ring is
minimized in a particularly effective way and, at the same time,
a significant weight saving is accomplished, without having a
reinforce the thermoplastic material with glass fiber or similar
additives. The inner ring 3 can have axial projections, known per
se, on both its sides 5, 6, which projections are mutually offset
in the radial direction, so that the hubs are protected against
shifting when they are stacked. In addition, the central bore 16
of the hub likewise has driving cut-outs 20, similarly known from
the prior art.
Instead of the annular axial projections 5, 6, mentioned above,
the inner ring 3 may also be provided with a plurality of
deformations 17, 18, which extend alternately to both sides in
the circumferential direction on the inner circumference of the
hub and respectively interlock when a number of hubs are stacked
one on top of the other, and in this way prevent them from being
rotated with respect to one another. Such hubs are known from the
already mentioned DE 24 48 853. As a result, the width of the
inner ring 3 on said embodiments is greater than the width of the
winding area 1. Figure 3 represents another embodiment, in which,
instead of the annular flexible intermediate elements 4, S-shaped
webs 7, extending in radial and circumferential directions, are
arranged evenly distributed.
Further, likewise advantageous embodiments of the present
invention can be seen from Figures 4, 6, 7 and 8. These
embodiments have in common that the hub does not comprise two
concentric rings, but that openings, evenly distributed over the
circumference on both sides, are provided between the outer
circumference or the winding area 1 and the inner bore 16, which
openings both mean a material saving and have the consequence of
the required compression of the outer circumference on account of
the winding pressure, so that the compression being transferred
hardly to the inner hub. The following shapes have proved
successful here:
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According to Figure 4, the circular openings 8, 9 are arranged in
one or more concentric circles, it being possible for the
openings to be of different sizes and to be arranged offset with
respect to one another.
5
Figures 5, 5a have as compression elements annular notches 11
which, as Figure 5a shows in cross-section, are on both sides
offset with respect to one another in the radial direction in a
meandering form.
According to Figure 6, the openings are punched out in a H
shape 12, the structure circumferentially at an acute angle with
respect to the as an example.
Figure 7 shows openings in zig-zag form 13.
Figure 8 represents chevron-like openings 15 in the
circumferential direction.
In the case of the abovementioned embodiments as well, axial
projections of deformations 5, 6, 17, 18 are provided in the
vicinity of the inner circumference or of the hub bore, as
already described in further detail above, in order in this way
to avoid a displacing or rotating of the hubs stacked one on top
of the other.
30
We now refer to the embodiments of Figures 9 to 19.
Thereof Figures 9 to 13 show embodiments With openings and S-form
webs in combination.
Figures 14 and 15 show S-form web embodiments with a specific
angular configuration and arrangements of the S-form webs and
Figures 16 to 19 show flexible deformable intermediate elements
in other forms or shapes than the S-form webs which are
comparable with the latter.
As can be seen from the cross-sections A and A' in Figure 9 the
above described double-T-profile can be strengthened by radial
webs 21 and/or by another annular ring R in the middle between
the double-T-form.
Figure 10 shows slightly oblique webs 22 for reinforcing
purposes. Advantageous is a trapezoidal arrangement of the
webs 22 with the rings.
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6
In Figure 11 and 12 the outer ring 2 is provided with annular
indentations 23, 24 or 25, 26 respectively from either side of
the hub. The rigidity substantially corresponds to that of the
double-T- or double-H-profiles showing in Fig. 9. Figure 13 shows
an outer ring 2 which possesses adjacent its outer periphery
(winding area 1) a series of going-through bores 28 which are
arranged close to one another.
In this example the S-form webs 27 have a different thickness at
their inner (i) and outer (a) radial portions. The inner
portions (i) are thicker than the outer ones (a).
Figure 14 shows specifically shaped S-form webs 47. Each web 47
consists of a circumferential or middle portions 43,43' and outer
and inner radial portions 44' and 45'. A radius beam 46 is shown.
Each middle portion 43,43' of the webs 47 is slightly slanted and
thus is located at an angle of a,a' being in the range of
85° < a,a' < 95°.
As shown in Figure 14 the S-form web 47 has an angle a -- 85°
versus the radius beam 46 and the following web 47' has another
angle a --- 95° versus the radius beam 46. Thus the elements 47 and
47' can be provided with alternating angles a and a'
respectively. There should be used pairs of such webs 47 and 47'
so that an equal number of webs 47 and 47' results. There have
been obtained still better results in the O Di/ODa ratio as in
the table at the end of the application.
Likewise good results with respect to the deviation ratio of
diameters Di divided by Da have been reached by the following
embodiment. Therein (Fig. 15) two adjacent webs 47" and 47" '
are located symmetrically to the radius beam 46 between one
another. Also pairs of such mirror-like located S-form webs 47 "
and 47" ' should be provided on each hub between inner ring 42
and outer ring 41. Such S-form webs 47" and 47" ' could also be
formed like one of the webs 47 and 47' in Fig. 14, so that both
webs 47" and 47" ' have the same angle a or a' versus the radius
beam 46. The anlge a can be varied to a' at the next following
pair of webs.
The same advantages as described above can be obtained by the
schematic hubs embodiments in Figs. 16 to 19 in which an inner
ring 3 and a very thin outer ring 2 are shown. Fig. 16 shows
chevron-like formed webs 28 directed in the circumference. Fig.
17 shows a rhombus-shaped web 29. The distances between two
subsequent webs 28 or 29 respectively are going-through openings.
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Figure 18 contains an egg-like form of web 30. It is also
possible to connect two or more subsequent webs 30 together.
Figure 19 has a zig-zag formed web 31 as the flexible deformable
intermediate element. Within the closed webs 29 and 30 there are
going-through openings as well as between two subsequent webs 28
to 31.
Each and all webs of Figs. 16 to 19 can replace the S-form webs 7
and 27 in the foregoing figures.
All herein described webs can advantageously have a thickness of
0.6 mm in minimum and normally about 1 mm and a width of
substantial the width of the winding area 1.
It is possible to use suitable web forms together with suitable
thermoplastic materials which are injection moldable. Such
thermoplastics must not contain any filler materials e.g., glass
fibers, glass beads and other reinforcing fillers.
Useful for hubs according the present invention are
thermoplastics in general in particular the following:
Polystyrene, ABS (Acrylo Nitrile Butadiene Styrene copolymers)
Mixture of polybuthyleneterephthalate with a polycarbonate.
PVC (Polyvinylchloride) (pls see the Examples)
Polyamide
It has been found in practice that the tape roll wound-up on the
hub is better secured against sliding movement on the hub when
the winding area of the outer ring is provided with a roughness
(RZ = five (5) point mean roughness according to DIN 4768) in the
range of about 8 ~tm to about 16 ~,m and more advantageously from
about 12 ~,m to about 14 ~.m, the latter in the case of polystyrene
material.
It was also found that the above roughness ranges are also
advantageous in the case of the other materials listed above.
Such roughness can be provided by a suitable mold or by means of
any suitably abrasive material by frictional movement against the
hub periphery or by any other suitable roughning method.
O.Z. 0078/05916
21.2.5
Example 1
On a hub having an outside diameter Da of 114 mm, a bore inside
diameter Di of 77 mm and having a width of 15 mm, consisting of
polyvinyl chloride without further additives and, as represented
in Figure 1, provided with 6 annular flexible intermediate
elements and double-T structure, a half-inch video magnetic tape
of a total thickness of 15.6 ~,m and a length of 5000 m was wound
up by a conventional winding apparatus and at a speed of
450 m/min. During this operation, the winding parameters, that is
tape tension and pressure of the contact roller pressing the
magnetic tape onto the hub, were chosen in such a way that a
winding pressure of 25 bar (25 N/mm2) acted on the winding surface
of the hub.
Example 2
On a hub having an outside diameter Da of 114 mm, a bore inside
diameter of 77 mm and having a width of 15 mm, consisting of
polyamide without further additives and, as represented in
Figure 3, provided with 12 S-shaped flexible intermediate
elements and double-T structure, a half-inch video magnetic tape
of a total thickness of 19 ~m and a length of 5000 m was wound
up,as described in Example 1.
Comparative Example
A commercially available hub, known as a NARTB hub, consisting of
glass fiber reinforced polystyrene and having the same dimensions
as in Example 1 but a cross-sectional constriction between
outside diameter and inner bore and 9 radial webs on both sides,
was wound with the sample tape under precisely the same
conditions as in Example 1.
The following table shows the reduction in the hub diameters
D Da, O Di on the wound hub of the example according to the
invention in comparison with a hub according to the prior art.
45
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Table
Hub accordingsExample 1 Example 1 Comparative
example
to
Modulus of 3800 3000 5500
elasticity
N mm Z
~ Da 0.5 mm 0.3 mm 0.5 mm
D i 0.1 mm 0.06 mm 0.4 mm
0, 2 0, 2 0, 8
D Da
O Di
Results: Example 1 and 2
A n ; __ -1.
D Da
Comparative Example
A n~ -~.
0 Da 5 - 1,25
Examples 3 to 6 have been performed with hubs for audio tapes.
Such hub has the same diameters Da = 114 mm and Di = 77 mm as the
hub for video tapes in Examples 1 to 2 and the Comparative
Example.
On the hub a 3.81 mm audio magnetic tape of a total thickness of
12 ~tm and a length of 3300 m was wound up at a speed of 250 m/min.
The mean winding pressure acting on the winding surface of the
hub was chosen to 15 bar.
Example 3
Material: Polystyrene without fillers
Design: Figure 3 (including flexible elements)
Example 4
Material: Polystyrene without fillers
Design: Figure 13 (including flexible elements)
Example 5
Material: Styrene Acrylo Nitrile with 30 % glass fibers
Design: according to DE 24 48 853
(without any flexible elements)
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Example 6 '~
Material : Styrene Acrylo Nitril
Design: Figure 4 (with annularly arranged holes as
sole flexible elements)
Hub Example 3 Example 4 Example 5 Example 6
Moduls of 3 200 3 200 5 000 5 000
Elasticity
N/miri 2
Da 0.2 0.2 0.2 0.2
Di 0.04 0.04 0.1 0.06
~Di/ODa 0.20 0.20 0.50 0.30
The examples 3 and 4 of the inventive designs show that the
deviations in the diameters lying with 0.2 = 1/5 (a fifth) under
the limit the compression ratio of 1:4 of the present invention.
Measurement Description
In the above Examples 1 - 6 and the Comparative Example the
deviations in the diameters of the hubs were measured by polar
distance (the distance from a predetermined fixed point e.g. the
midpoint) of the circular form of the outer and inner hub
peripheries. The hub was hold at the three driving cut-outs e.g.
in Figre 3 and at 6 equidistant points between two cut-outs there
the polar distance value was measured. The maximum value was
taken as the value in the above tables.
Results of the tests
Practically it has been found in tests that a ratio of
is at maximum tolerable because the hubs could be still
0 Da 4
removed from the axle whereon the hub is provided with the media
pancake at very high winding speeds.
For still easier removal of the hubs with their pancakes thereon
the ration of 1:5 is far better.
In the comparative Example more than 500 of the hubs could not
been removed after the winding process was finished.
As regards the hub materials it is important that the used
material does not constrict under longer treatment under higher
temperatures.
