ES345072A1 - Magnetic calender - Google Patents

Abstract

To vary the pressure between two rolls 2, 34 in a machine for pressing flexible materials, e.g. paper or textiles, the roll 2 comprises a shell 4 rotatably mounted in brackets 16 on a frame, and a shaft 6 rigidly carried by rods 24 on the frame, the shaft carrying magnetic means 8 eccentrically within the shell to attract one side of the shell towards the shaft and hence to force the diametrically opposite side into contact with roll 34. The magnetic means 8 may be a permanent magnet, a single electromagnet, or a plurality of series-connected electromagnets, and the current to the electromagnets may be varied to vary the force exerted by the shell 4 on the roll 34. This force may alternatively, or additionally, be varied, to take account of varying thickness and/or density of the flexible material, by means of a strain gauge 32 which, on any change in the pressure between shell 4 and roll 34 from a preset value, automatically actuates a motor 30 to adjust a bar 28 to raise or lower arms 26 carrying rods 24. To compensate for any deflection of the roll 2 due to its ends being fixed, the shaft 6 is attached at each end to mountings 18 which in turn are attached to a tension bar 20 provided with an adjustment 22, the bar 20 exerting a force on the shaft mountings in opposition to the stress created by magnet 8. The tension bar may therefore be utilized to give no deflection of the shaft when the magnetic force is exerted, or to give a positive or negative crown to the roll. Cooling or heating fluid may flow through either roll 2 or 34. When the roll 2 is utilized for heating or cooling, the fluid may be introduced and withdrawn at one or both ends, the inlets or outlets being formed at the top or bottom of the roll respectively. The flexible material may be forcibly drawn through the gap between the rolls, or either roll may be driven.