rolling and stretching thus take place directly in liquid He, H2, or N 2.
The main parts of the roller drive and of the specimen stretching mechanism are outside the low temperature region when the mechanical properties are being studied. The turning moment from drive 4, mounted on plate 5 of the frame, is transmitted to the roller through identical gears 6, linked together to produce synchronized rotation of both rollers. The rolling rate can be changed within wide limits by a simple readjustment of the drive. Gears 6 are connected to the roller reduction gears by the hollow stainless steel extension shafts 7. Shafts 7 are provided with hinged couplings 8 and the connexions of the roller reduction gears to them are telescopic. The roller drive mechanism is reversible.
The closeness of the rollers is set by knob 9 through a similar shaft. The gap between the rollers can be set with great accuracy by the turn counter (one revolution corresponds to a change of 0.05 mm in the gap).
The three-speed mechanism for stretching the specimen at constant speed, 11, is mounted on plate 12. Rod 13 is connected to the loading screw 14 through the stiff dynamometer 15 which is in the form of a split spring. The deformation of the dynamometer is measured by the induction probe 16. A high measuring accuracy is achieved by arranging it on the axis of application of the load. The extension diagram is plotted automatically by a PSR-08 potentiometer, fixed on the electrical control panel 17.
The main features of the apparatus are: rolling diameter 30 mm; length of their working part 18 mm; rolling rate from 0"1 to 10 mm min -1 ; maximum load of the interchangeable dynamometers 5, 10, 25, 50, and 100 kg. Rate of stretching 0-5, 1"7, and 5"5 mm min -1. The thickness of copper foils stretched at 77 K is 0.03 mm.
PR is with the Centre d'Etudes Nuclaires de Saclay, BP no 2-91--Gif-sur-Yvette, France. JV is at the Division de Physique Nucl~aire,