Glass manufacturing – Processes of manufacturing fibers – filaments – or preforms – With measuring – controlling – sensing – programming – timing,...
Patent
1997-05-30
1999-09-21
Hoffmann, John
Glass manufacturing
Processes of manufacturing fibers, filaments, or preforms
With measuring, controlling, sensing, programming, timing,...
65382, 65469, C03B 3701
Patent
active
059548525
DESCRIPTION:
BRIEF SUMMARY
This invention relates to processes by which Man-Made Vitreous Fibre products (MMVF products) can be made. Such products include slabs, sheets, tubes and other shaped products of use as thermal or fire insulation or protection, noise reduction or regulation, or a fibre reinforcement of cement, plastics or other materials, or a filler, or as horticultural growing medium.
It is well known to make MMVF products from a mineral melt by pouring mineral melt on to the top rotor of a cascade of rotating rotors each mounted about a different substantially horizontal axis and arranged such that the melt is thrown from the top rotor on to the subsequent rotor, or each subsequent rotor in sequence, in the cascade so as to throw fibres off the or each subsequent rotor, collecting the fibres as a batt (generally in the presence of binder), and consolidating the batt into the desired MMVF product. Suitable apparatus is described in WO92/06047.
In conventional processes using conventional melts, the acceleration field on the top rotor is typically very low, for instance 10 to 15 km/sec.sup.2 and is intended primarily to accelerate the melt on to the subsequent second rotor where the acceleration field is much higher.
Thus typically the process is operated with an acceleration field of around 15 km/sec.sup.2 on the top rotor and 30 to 100 km/sec.sup.2 on the subsequent rotors, with the highest value being for the last rotor.
It is desirable to minimise the amount of shot (material having a diameter above 63 .mu.m) in the MMVF product and to obtain a reasonably uniform fibre diameter in the product. This is why it has been conventional to arrange for the top rotor to provide an acceleration force very much less than the acceleration force provided by the subsequent rotors. Thus it has been accepted that satisfactory fibre formation by the top rotor would be difficult to achieve and would be likely to be accompanied by significant shot formation, so that the top rotor should primarily serve to accelerate the melt that is to be thrown against the first subsequent rotor, with fibre formation being confined primarily to the subsequent second and later rotors.
Such processes are suitable for mineral melts of the type which have traditionally been used for making MMVF products, especially from rock, stone or slag. Other processes which are also intended for use with conventional melts are described in WO92/12939 and WO92/12941. For instance we describe in WO92/12939 that the first rotor is provided with driving means and has a size such that it can rotate to give an acceleration field of at least 50 km/s.sup.2 and the second and third rotors each have a size and can rotate such as to give a greater acceleration field than the first rotor, and the axes of the first and second rotors are arranged such that a line drawn from the axis of the first rotor to the axis of the second rotor makes an angle of from 0 to 20.degree. C., preferably 5 to 10.degree., below the horizontal. In this apparatus, the acceleration field provided by the first rotor can be up to around 150 km/s.sup.2, or even greater in some circumstances, but is generally below 100 km/s.sup.2. The ratio of the acceleration field of the second rotor to the first rotor is generally from 1.1:1 to 2:1, preferably around 1.2:1 to 1.7:1 and the ratio of the acceleration field on each subsequent rotor to the preceding rotor is generally 1.2:1 to 1.6:1. The acceleration field provided by the final rotor typically is from 150 km/s.sup.2 to 300 km/s.sup.2, or even greater in some instances.
All such processes are intended for use with conventional melts having conventional melting properties. Such melts contain, for instance, significant amounts of alumina and are formed from materials such as basalt and diabase. The literature generally describes such melts as being applied on to the top rotor while at a temperature in the range 1350 or 1400.degree. C. to 1600.degree. C., but in practice it is normal to apply at a temperature of around 1420 to 1480.degree. C. The use of higher te
REFERENCES:
patent: 2632919 (1953-03-01), Koehler
patent: 4026478 (1977-05-01), Albert
patent: 5332699 (1994-07-01), Olds
patent: 5401693 (1995-03-01), Bauer
Grove-Rasmussen Svend
Jensen Carsten
Hoffmann John
Rockwool International A/S
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