This report reviews the principle of and problems encountered in the process of commercialization of the low temperature grinding system “CRYOMILL” which has been developed by the authors. The principle of the system “CRYOMILL” is to cool materials having low temperature brittleness such as thermoplastic etc. by liquid nitrogen injection down to the temperature below its glass transition point and to grind the material by high-speed revolving mill. During grinding process it is necessary to control heat generation which is inherent to the material and the key point in commercialization is to utilize cold energy effectively throughout the total system.
This article gives a short survey of the process of low temperature grinding. A special emphasis is given on the clean high recycle process (CHR process), which has been developed by our company in order to treat small-size motors and wires.
In Germany the project group of AEG, BBC and Siemens had succeeded in magnetically suspended test run with superconducting magnets for the first time in March 1976 on a circular test track in Erlangen. The test vehicle was propelled by an on-board linear induction motor. A clearance of 100mm between the track surface and the bottom of cryostats was achieved at 120km/h. Furthermore, a rotating drum test-rig for linear synchronous motor (LSM) is in preparation for conversion of the circular track to LSM system, because in future practical system the trains will be propelled by LSM. Outline of the plan for practical system is described also.