# US 5,707,025 A · Hub for winding magnetic tapes

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- Number: US 5,707,025 A
- Document ID: US5707025A
- Status: Granted
- Kind: A
- Application number: 08/688,950
- Filed: 1996-07-31
- Granted: 1998-01-13
- Earliest claimed: 1995-08-01
- Assignees: EMTEC Magnetic GmbH
- Inventors: Jurgen Schmidt; Bernd Scholtysik
- Web page: https://patentgrep.com/patent/US5707025A

## CPC

- G11B 23/037: Single reels or spools
- B65H 75/10: without flanges, e.g. cop tubes
- G11B: INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER (recording measured values in a way that does not require playback through a transducer G01D9/00; recording or playback apparatus using mechanically marked tape, e.g. punched paper tape, or using unit records, e.g. punched or magnetically marked cards G06K; transferring data from one type of record carrier to another G06K1/18; circuits for coupling output of reproducer to radio receiver H04B1/20; gramophone pick-ups or like acoustic electromechanical transducers or circuits therefor H04R)
- B65H: HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES

## Abstract

A cylindrical hub for winding web-like or tape-like magnetic recording media of relatively great length. With a winding tension of not more than 2N/cm width of the wound magnetic recording medium, the skew measured over the total length of the wound recording medium should be not more than 5 .mu.s. The length of the wound recording medium is at least 5,000 m; the hub may consist, for example, of aluminum, steel or hard pertinax. It was found that the conditions are fulfilled by a hub in which the compression is less than 0.3% of the hub diameter.

## Claims

### Claim 1

A hollow cylindrical hub for winding a magnetic tape having a length of at least 5000 meters, wherein the condition is fulfilled, that the hub diameter divided by the modulus of elasticity of the hub material and by the wall thickness of the hub is less than the factor 6.multidot.10.sup.-3 divided by the winding pressure on the winding surface of the hub in a formula ##EQU5## in which p=winding pressure on the winding surface of the hub
D=hub diameter
E=modulus of elasticity of the hub material
w=wall thickness of the hub.

### Claim 2 (depends on 1)

A hub as defined in claim 1, wherein the reduction of the hub diameter is less than 0.3%.

### Claim 3 (depends on 1)

A hub as defined in claim 1, which consists of the group of materials steel, aluminum, hard pertinax or another plastic which optionally may contain reinforcing material.

### Claim 4 (depends on 1)

A hub as defined in claim 1 wherein the hub surface has a center line average value Ra of not more than 10 .mu.m.

### Claim 5

A magnetic tape having a length of at least 5,000 meters, wound on a hollow cylindrical hub according to the condition that the hub diameter divided by the modulus of elasticity of the hub material and by the wall thickness of the hub is less than the factor 6.multidot.10.sup.-3 divided by the winding pressure on the winding surface of the hub ##EQU6## in which p=winding pressure on the winding surface of the hub
D=hub diameter
E=modulus of elasticity of the hub material
w=wall thickness of the hub, whereby the magnetic recording media after winding has a skew error of not more than 5 .mu.s over its total length of at least 5000 meters.