Cutting – Other than completely through work thickness or through work... – Splitting
Patent
1994-07-11
1997-04-15
Peterson, Kenneth E.
Cutting
Other than completely through work thickness or through work...
Splitting
83395, 83451, 83948, B26D 300
Patent
active
056198981
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a process for mechanically removing foreign substances from the substrate material of a disk-shaped information carrier, especially of an optically scannable information carrier, for the recovery of the substrate material. The invention further relates to a device for the realization of the process.
The manufacture of such types of disk-shaped information carriers, such as optically readable video disks or digital audio disks (compact disks), is currently managed only with a relatively high reject rate, so that approx. 50% of the original raw material used ends up as reject material. In order to reduce the quantity of waste, it has therefore been proposed to recover the substrate material for the disk-shaped information carriers, generally polycarbonate, to enable it to be used again, after granulation, for the manufacture of disk-shaped information carriers. For this it is necessary that the foreign substances, which regularly extend, in the said information carriers, across the entire surface of the information carrier on one side, should be reliably removed so as to enable the substrate material to be available for reuse at the required level of purity.
The foreign substances on a compact disk comprise a metal layer, a varnish layer and an ink impression. It has been proposed to remove these foreign substances by chemical means. Further waste disposal problems are herein generated by the aggressive chemical materials which are used.
It has further been proposed to remove the foreign substances by mechanical means, to be precise by the use of a particle-jet or an abrasive tool which results in the foreign material being ground off. These processes too have failed to produce the desired success.
The object of the invention is therefore to enable a reliable, mechanical removal of the foreign substances from the substrate material of disk-shaped information carriers, in which no new waste disposal problems are to be generated by the removal of the foreign substances.
This object is achieved according to the invention, using a process of the type mentioned in the introduction, by the fact that the foreign substances-containing coating are [sic] removed from the substrate material by a metal-removing cut.
The concept forming the basis of the invention accordingly consists in removing the foreign substances-containing layer by a cut having a defined depth of cut, the cut being able to extend across the entire width of the information carrier, so that, using a single drawing cut, the entire foreign substances-containing coating of the substrate material is peeled off.
For the realization of the process according to the invention, no pollutant auxiliary materials, such as chemicals or abrasive grainy materials, are necessary. The foreign substances-containing layer is yielded in the form of chips and can then be crushed and disposed of. The disk, made from the substrate material, which has been freed from the foreign substances, is available for use in a pure form having a relatively high surface quality, which can be further enhanced by the top side, at least, of the disk-shaped information carrier, which top side exhibits the foreign substances, being moistened prior to the cut. The moistening can also herein apply, however, to the entire information carrier.
The critical observance of the defined depth of cut is aided by the fact that, during the cut, the information carrier is pressed from its top side, for positional fixing purposes, into a receiving fixture. The receiving fixture, which is formed by an indentation, has preferably in this case a diameter which corresponds to the outside diameter of the disk-shaped information carrier. The pressing of the information carrier into the receiving fixture produces a secure positioning of the information carrier during the cut.
Preferably, a cutting angle of .+-.10.degree. is used. In particular where a negative cutting angle is applied, it is possible to obtain a high surface quality for the remaining substrate material.
The information
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Patent Abstracts of Japan, vol. 16, No. 43, (C-907), abstract of Hara, "Production of Stamper for Optical Disk", Japanese 3-247788, Nov. 5, 1991.
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