DE9400220U1 - Winding core for information carriers - Google Patents

Description

- O.Z. 0078/05916 ""' Winding core for information carriers

Description

Winding core for wound strip or tape-shaped information carriers, wherein the width of the outer winding surface of the winding core essentially corresponds to the width of the information carrier to be wound, the winding core has a central bore and has driver cutouts on its inner circumference and is equipped with an outer and an inner ring which are connected to one another.

After the magnetic coating has been produced, information carriers, such as magnetic tapes, are cut to the required width on a strip-shaped, flexible layer carrier and wound onto flange reels or flangeless winding cores in lengths of up to several thousand meters. To do this, the winding core with its central bore is placed on the drive shaft of a winding machine and the information carrier is wound up at high speed and with a correspondingly adjusted winding pressure. In general, the winding cores have cross-sectional area constrictions between the outer winding surface and the inner circumference to save costs and weight, with radially extending stiffening ribs being provided to increase stability in this material thinning zone. An example of such a winding core is given in DE-GM 77 22 919. A stackable winding core in which the stacked tape reels are secured against twisting and thus damage is known from DE-PS 24 48 853.

When winding the information carriers onto the winding cores mentioned above and during rewinding, the tape tension can be so high that the core bore narrows due to the winding pressure, which means that the cores can no longer be aligned with the drive shaft of the winding device.

To counteract this problem, it is known to manufacture the winding cores from glass-fiber reinforced plastic and, if necessary, to dispense with the aforementioned material thinning; metal winding cores are also used. However, these solutions have significant disadvantages due to weight and cost.

From the aforementioned DE-GM 77 22 919, the teaching is known to provide a radially extending threading slot to avoid narrowing the core bore, which narrows during winding and thereby absorbs the winding tension. From US-PS 3 632 053, a flange coil is known whose winding core has the generic properties mentioned at the beginning and in which, in order to avoid transferring the compression to the flanges, elastic intermediate elements are provided between the winding core and the flange. But, as is clear from the description, this known winding core also requires glass fiber reinforced polystyrene or metal as the core material. In the description EP OS 375 322 by the same applicant, it can also be read that, despite the elastic intermediate elements, the inner diameter of the winding core is still compressed too much. In the latter document, it is proposed to avoid this compression by providing a number of diagonally running ribs between the outer and inner ring, which have a reduction in thickness over their length, which result in the outer ring twisting against the inner ring. US 4 052 020 discloses a reel for a computer tape, in which the outer winding surface of the core is covered with an elastic surface in order to absorb the tension that arises during winding.

FR-OS 22 33 675 describes a tape reel intended for a tape cassette, which has a double-Y cross-section and is provided with elastically deformable arch-shaped arms between the inner and the

outer ring of said reel. These deformable arms serve to facilitate the insertion of the drive shafts into the drive openings when the drive shafts of the device engage in these openings. General tape winding problems are not to be solved here.

Based on the above-mentioned prior art, the object to be solved within the scope of the present invention was to create a winding core of the generic type mentioned at the beginning, which does not have the disadvantages of the prior art, which is also made of plastic and should not require any reinforcing additives, such as glass fibers or glass beads, because this causes recycling problems. Furthermore, the object to be solved within the scope of the present invention was to ensure that when stacking several cores with tape windings, so-called pancakes, on top of each other, the tape winding does not form a dish and that such a pancake stack does not cause any problems during transport and storage.

According to the invention, the object was achieved with a winding core for wound up strip or tape-shaped information carriers, wherein the width of the outer winding surface of the winding core essentially corresponds to the width of the information carrier to be wound up, the winding core has a central bore and has driver cutouts on its inner circumference and is equipped with an outer and an inner ring which are connected to one another by elastically deformable intermediate elements running radially and in the circumferential direction in order to prevent a relative movement of the outer ring with respect to the inner ring in its circumferential direction, wherein the winding core with the wound up information carrier has 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 comprises a winding core for wound strip- or tape-shaped information carriers, wherein the elastically deformable intermediate elements are formed as residual sections between openings which are arranged in a row and in a uniform distribution over the circumference of the winding core.

A further embodiment of the invention comprises a flangeless stackable winding core for wound up tape-shaped information carriers, wherein the width of the winding surface of the winding core corresponds essentially to the width of the information carrier to be wound up, the winding core has a central bore and has driver cutouts on its inner circumference and is equipped with an outer and an inner ring, which are connected to one another by elastically deformable intermediate elements running radially and in the circumferential direction in order to prevent a relative movement of the outer ring with respect to the inner ring in its circumferential direction, wherein between the outer circumference and the inner circumference several concentric circular ring-shaped notches are provided, which are arranged offset in the radial direction in relation to one another in a meandering shape.

Further details of the invention as well as expedient embodiments are contained in the subclaims, the drawings and the description.

The invention will now be explained in more detail with reference to the drawings, in which
0 Fig. 1 is a plan view of a first embodiment

of the winding core according to the invention
Fig. 2 a cross section through a winding core according to

Figure 1 along line II/II

Fig. 3-19 Top views of further preferred embodiments of the winding according to the invention

core with elastic elements.
A feature of the embodiment according to the figures

1 and 2 is that the outer ring 2 of the winding core consisting of two concentric rings has a double-T structure, as can be seen in the cross section, and that between the outer ring 2 and the inner ring 3, circular elastic intermediate elements 4 are arranged evenly distributed in the circumferential direction. The combination of the double-T profile and the elastic intermediate elements 4 mentioned reduces the transfer of compression from the outer to the inner ring in a particularly effective manner and at the same time achieves a significant weight saving, without having to reinforce the thermoplastic material with glass fibers or similar additives. The inner ring 3 can be equipped with known axial projections on both sides -5, 6, which are offset from one another in the radial direction so that when the winding cores are stacked, they are protected against displacement. In addition, the central bore 16 of the winding core also has driver cutouts 20 known from the prior art.

Instead of the above-mentioned circular axial projections 5, 6, the inner ring 3 can also be provided with several deformations 17, 18 extending alternately to both sides on the inner circumference of the winding core in the circumferential direction, which engage with each other in a form-fitting manner when several winding cores are stacked on top of each other and in this way prevent mutual twisting. Such winding cores are known from the aforementioned DE 24 48 853.

As a result, the width of the inner ring 3 in the embodiments mentioned is greater than the width of the winding surface 1. Another embodiment is shown in Figure 3, in which instead of the circular elastic intermediate elements 4, S-shaped webs 7 extending in the radial and circumferential directions are arranged evenly distributed.

Further, equally advantageous embodiments

- 6 A :.·*..; ;0.·&Zgr;.* O»9y8*jö5916

of the present invention can be seen from Figures 4, 5, 7 and 8. These embodiments have in common that the winding core does not consist of two concentric rings, but that openings are provided on both sides between the outer circumference or the winding surface 1 and the inner bore 16, evenly distributed over the circumference, which both mean a saving in material and result in the required compression of the outer circumference due to the winding pressure, without the compression having a significant impact on the inner winding core. The following shapes have proven to be successful:

According to Figure 4, the circular openings 8, 9 are arranged in one or more concentric circles, wherein the openings have different sizes and can be arranged offset from one another.

Figures 5, 5a have ring-shaped notches 11 as compression elements, which, as shown in Figure 5a in cross section, are offset from one another in a meandering manner on both sides in the radial direction.

According to Figure 6, the openings are formed in an H-shape 12, with the structure in the circumferential direction at an acute angle to the radius being preferred.

Figure 7 shows openings in zigzag shape 13.
Figure 8 shows arrowhead-like openings 15 in the circumferential direction.

In the aforementioned embodiments, axial projections or deformations 5, 6, 17, 18 are also provided near the inner circumference or the core bore, as already described in more detail above, in order to avoid displacement or twisting of the stacked winding cores.

We now refer to the embodiments of Figures 9 to 19.

Figures 9 to 13 show embodiments with openings and S-shaped webs in a combined design.

Figures 14 and 15 show embodiments

the S-shaped webs with special angle formation and arrangements of the S-shaped webs, and the

Figures 16 to 19 show elastically deformable intermediate elements that have different shapes or configurations than the S-shaped webs with which they are comparable.

As can be seen from the cross sections A and A' in Figure 9, the double-T profile described above can be reinforced in the middle between the double-T shape by radial webs 21 and/or another circular ring R.

Figure 10 shows slightly slanted webs 22 which serve as reinforcement. A trapezoidal design of the webs 22 including the rings is advantageous.

In Figures 11 and 12, the outer ring 2 is provided with circular recesses 23, 24 and 25, 26 on one side of the winding core. The rigidity corresponds essentially to that of the double-T or double-H profiles shown in Figure 9. Figure 13 shows an outer ring 2 which has a series of through holes 28 near its outer circumference (winding surface 1) which are arranged close to one another.

In this example, the S-shaped webs 27 have different thicknesses at their inner (i) and outer (a) radial sections. The inner sections (i) are thicker than the outer sections (a).

Figure 14 shows specially designed S-shaped webs 47. Each web 47 consists of a peripheral or central section 43, 43' and of the outer or inner radial section 44', 45'. The figure contains a radius beam 46. Each central section 43, 43' of the webs 47 is arranged slightly obliquely and thus has an angular position a, a' in the range of 85° s a, a' s 95°.

The S-shaped web 47 is, as shown in Figure 14,

is arranged at an angle α ~ 85° with respect to the radius beam 46, and the following web 47 ' has a different angle α ~ 95° with respect to the radius beam 46. Thus, the elements 47 and 47' can be arranged alternately with the angular position α or a' . Full pairs of these webs 47 and 47' should be provided in each case so that an equal number of webs 47 and 47' results. Even better results have been achieved with the ADi/ADa ratio as in the table (at the end of the application).

Likewise good results with regard to the deviation ratio of the diameters Di divided by Da have been achieved with the following embodiment. In this case (Figure 15), two adjacent webs 47'' and 47'' are arranged symmetrically to the radius beam 46 running between them. In addition, pairs of these mirror-image S-shaped webs 47'' and 47''' should be provided on each winding core 41. These S-shaped webs 47'' and 47''' could also be designed in their shape like one of the webs 47 and 47' in Figure 14, so that both webs 47'' and 47''' have the same angle a or a' with respect to the radius beam 46. The angle α can be changed to α' in the next pair of these webs.

The same advantages described above can be achieved with the embodiments of the winding cores shown in Figures 16 to 19. Figure 16 shows arrowhead-shaped webs 28 arranged in the circumferential direction. Figure 17 shows a rhombus-shaped web 29. The spaces between the two consecutive webs 28 and 29 are designed as continuous openings.

Figure 18 shows an egg-shaped web 30. It is also possible to connect two or more consecutive webs 30 together. In Figure 19, a zigzag-shaped web 31 is shown as an elastically deformable intermediate element. Within the

- 9 -* ** &idgr; * J p. 3 ■

Through openings are formed between the closed webs 29 and 30 and between two consecutive webs 28 to 31.

Each web and all webs of Figures 16 to 19 can replace the S-shaped webs 7 and 27 in the previous figures.

All webs described herein may preferably have a minimum thickness of 0.6 mm and normally a thickness of about 1 mm and a width which substantially corresponds to the width of the winding surface 1.

It is possible to use suitable bridge shapes together with

suitable thermoplastic materials that can be processed using the injection molding process. Such thermoplastics must not contain fillers such as glass fibers, glass beads and other reinforcing fillers.

Thermoplastics in general, in particular the thermoplastics listed below, are suitable for winding cores according to the present invention:

Polystyrene, ABS (acrylonitrile/butadiene/styrene copolymers).

Mixture of polybutylene terephthalate with a polycarbonate.
PVC (polyvinyl chloride) (see examples).

polyamide

It has been found in practice that the wound information carrier, in short the tape roll, is better secured against slipping and shifting on the winding core if the winding surface on the circumference of the outer ring is provided with a roughening of the roughness depth R _z 0 (DIN 4768) in the range from about 8 μια to about 16 μια, and advantageously from about 12 μια to about 14 μια in the case of polystyrene material. It has also been found that the roughness ranges given above can also be used appropriately in the case of other materials mentioned above. The roughening

can be applied using a suitable injection mold or using friction material that is moved relative to the winding surface of the winding core or vice versa, other suitable methods for roughening plastics can also be used.

example 1

A half-inch video magnetic tape with a total thickness of 15.6 /im and a length of 5000 m was wound on a winding core with an external diameter Da of 114 mm/ an internal bore diameter Di of 77 mm and with a width of 15 mm, consisting of polyvinyl chloride without further additives, which, as shown in Figure 1, is designed with 6 circular elastic intermediate elements and a double-T structure, on a conventional winding device and at a speed of 450 m/min. The winding parameters, ie tape tension and contact pressure of the contact roller pressing the magnetic tape onto the winding core, were selected so that a winding pressure of 25 bar (25 N/mm ² ) acted on the winding surface of the winding core.

Example 2

A half-inch video magnetic tape with a total thickness of 19 /im and a length of 5000 m was wound onto a winding core with an outer diameter Da of 114 mm, an inner bore diameter of 77 mm and a width of 15 mm, consisting of polyamide without further additives, which, as shown in Figure 3, is designed with 12 S-shaped elastic intermediate elements and a double-T structure, as described in Example 1.

Comparison example

A commercially available so-called NARTB winding core, consisting of glass fiber reinforced polystyrene with the same dimensions as in Example 1, but

•O.g.· &Ogr;&thgr;&Iacgr;8/&iacgr;35916

has a cross-sectional constriction between the outer diameter and the inner bore and has 9 radial webs on both sides, was wound with the same tape under exactly the same conditions as in Example 1.

The following table shows the reduction in core diameters ADa, ADi for the wound core according to the examples according to the invention in comparison to a wound core according to the prior art.

Table

Winding core
according to example 1 example 1 Comparison
example E-modulus
Nmm' ² 3800 3000 5500 ADa -
ADi 0.5mm
0.1mm 0.3mm
0.06mm 0.5mm
0.4mm ADa
ADi 0.2 0.2 0.8

Results: Example 1 and 2
ADi , 1

AD 5

Comparison example
ADi , 4

AD 5

1
1.25

Examples 3 to 6 were carried out with winding cores for audio tapes. Such a winding core has the same diameters Da = 114 mm and Di = 77 mm as the winding core for video tapes in examples 1 to 2 and in the comparison example.

An audio magnetic tape of 3.81 mm with a total thickness of 12 μπλ and a length of 3300 m was wound onto the winding core at a speed of 250 m/min. The average winding pressure acting on the winding surface of the winding core was selected to be 15 bar.

Example 3

Material: Polystyrene without fillers Design: Figure 3 (with elastic elements)

Example 4
Material:
Execution:

Polystyrene without fillers

Figure 13 (with elastic elements)

Example 5
Material:
Execution;

Styrene/acrylonitrile with 30% glass fibers according to DE-PS 24 48 853 (without elastic elements)

Example 6

Material:

Execution:

Styrene/Acrylonitrile

Figure 4 (with ring-shaped holes as the only elastic elements)

Wrap
core Example
3 Example
4 Example
5 Example
6 E-modulus
N/ ^mm2 3200 3200 5000 5000 There 0.2 0.2 0.2 0.2 Tue 0.04 0.04 0.1 0.06 ADi/ADa 0.20 0.20 0.50 0.30

Examples 3 and 4 of the embodiments according to the invention show that the deviations in the diameters of 0.2 = 1/5 (one fifth) are below the limit of the compression ratio of 1:4 of the present invention.

In the above examples 1 to 6 and in the comparison example, the deviations in the diameters of the winding cores were measured over the pole distance (the distance from a predetermined fixed point, e.g. the center) of the circular shape of the outer and inner winding core circumferences. The winding core was measured at the three

- is

driver cutouts, e.g. in Figure 3, and the pole distance value was measured at 6 points with equal distance between the two cutouts. The maximum value was taken as the value for the tables above.

Test results

In the tests it was practically established that a ratio of

ADi . 1

AD 4

is maximally tolerable because the winding cores could still be pulled off the axis on which the winding core was provided with the tape winding at very high winding speeds.

To further simplify the removal of the winding cores with the tape windings on them, a ratio of 1:5 is far better.

In the comparison example, more than 50% of the winding cores could not be removed after completion of the winding process.

As far as the winding core materials are concerned, it is important that the material used does not contract during prolonged use at higher temperatures.

Claims (21)

BASF Magnetics GmbH O. Z. 0078/05916 Protection claims 1. Winding core for wound-up strip or tape-shaped information carriers, the width of the outer winding surface (1) of the winding core essentially corresponding to the width of the information carrier to be wound up, the winding core having a central bore (16) and driver cutouts (20) on its inner circumference and being equipped with an outer and an inner ring (2 and 3 respectively) which are connected to one another by elastically deformable intermediate elements running radially and in the circumferential direction in order to prevent a relative movement of the outer ring (2) with respect to the inner ring (3) in the circumferential direction thereof, characterized in that the winding core with the wound-up information carrier has a compression ratio of the compressed diameter of the inner ring ADi to the compressed diameter of the outer ring (ADa) of less than 1:4. 2. Winding core according to claim 1, wherein the compression ratio is 1: 5. 3. Winding core according to claim 1 or 2, characterized in that the said outer and inner ring (2, 3) as well as the elastically deformable intermediate elements (4, 7, 8, 9, 11-13, 15, 21-31, 47, 47', 47", 47'") consist of thermoplastic material without filler. 4. Winding core according to one of claims 1 to 3, characterized in that the axial projections are provided along the inner bore (16) on both sides of the winding core such that the width of the winding core at the inner bore (16) is greater than the width of the winding surface (1), the projections preventing mutual twisting and/or displacement when the winding cores are stacked on top of one another. 5. Winding core according to one of claims 1 to 4, characterized in that the elastic intermediate elements are designed as S-shaped, radially and in 23.12.1993 O07S7US916 webs (7, 27, 47, 47', 47'', 47''') running in the circumferential direction are formed. 6. Winding core according to one of claims 1 to 5, characterized in that the elastic intermediate elements are designed as egg-shaped webs (30). 7. Winding core according to one of claims 1 to 5 ₁ , characterized in that the said elastic intermediate elements are designed as zigzag-shaped webs (31). 8. Winding core according to one of claims 1 to 4, characterized in that the elastic intermediate elements are designed as arrowhead-like webs (28) in the circumferential direction. 9. Winding core according to one of claims 1 to 4, characterized in that the elastic intermediate elements mentioned are designed as webs in the form of rhombuses (29) with a longitudinal axis running in the circumferential direction. 0 10. Winding core according to one of claims 1 to 4, characterized in that the elastic intermediate elements are designed as residual sections between openings (12) which are arranged in series and formed in a &EEgr; shape. 11. Winding core according to one of claims 1 to 4, characterized in that the elastic intermediate elements are designed as residual sections between openings (13) which are arranged in series and shaped like a zigzag. 0 12. Winding core according to one of claims 1 to 4, characterized in that the elastic intermediate elements are designed as residual sections between openings which are arranged in a row, the openings (15) having an arrowhead-like shape aligned in the circumferential direction. 13. Winding core according to claim 1, characterized in that said elastic intermediate elements consist of a combination of a) radially and circumferentially extending elastic webs (7, 27) and b) remaining sections between openings (13-26, 28) arranged in series, wherein said openings are provided between the circumference of the outer ring (2) and said elastic webs (7, 27). 14. Winding core according to claim 1 and 5, characterized in that the said elastic intermediate elements are designed as S-shaped webs (7, 27, 47, 47', 47", 47''') which consist of a peripheral section with a substantially radially extending section at each of their ends. 15. Winding core according to claim 1 and 5, characterized in that the elastic intermediate elements mentioned are designed as S-shaped webs (7, 27, 47, 47', 47", 47"') which essentially consist of a peripheral section with a radial section at each of their ends, the section (43) essentially designed as a peripheral section being at an angle of approximately 85° to approximately 95° in relation to any radius (46) of the winding core. 16. Winding core according to one of claims 1 and 5, 13 or 15, characterized in that the said S-shaped webs (7, 27, 47, 47', 47", 47'") are provided in an even number.
17. Winding core according to one of claims 1 and 5, 13, 15 or 16, characterized in that the successively arranged S-shaped webs (47", 47"') are provided symmetrically to a radius (46) running between them.
18. Winding core according to one of claims 1 to 17, characterized in that the thermoplastic material is a polystyrene without filler. · 19. Winding core according to one of claims 1 to 17, characterized in that the thermoplastic material is an ABS without filler. 20. Winding core according to one of claims 1 to 17, characterized in that the thermoplastic material is a mixture of a polybutylene terephthalate with a polycarbonate. 21. Winding core according to one of claims 1 to 20, characterized in that the winding surface (1) has a roughening with a roughness depth R _z in the range from about 8 μm to about 16 μm, in particular from about 12 μm to about 14 μm.
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