Patent GB-563480-A (GB)
Title: Improvements relating to the drying of travelling fabrics
IPC: D06C7/00
Filed: 1942-10-01
Abstract: 563,480. Electric control systems. DALGLISH, M., COOK, M. C., and DALGLISH, J. (trading as DALGLISH & SONS, J.), and LAURIE, K. S. Oct. 1, 1942. No. 13759. [Class 38 (iv)] [Also in Groups XIII and XXXVI] The drying of travelling fabrics is controlled by making regulating adjustments of the drying in steps, the direction of each step being determined at the start of the step by the current in an electric control circuit whose resistance varies with the moisture content of the fabric. The selvedges of the travelling fabric 12, Fig. 1, are gripped by grippers 10, a heater being arranged to dry the fabric as it passes in the stretched condition. A brass or other sheet metal contact roller 13 presses against the fabric midway between the grippers 10 and is connected to the secondary winding of a step-up transformer 17, the circuit of which includes a milliammeter 20 calibrated to indicate percentage of moisture content. Relay coils 21, 22, 23 are also connected in the secondary circuit through a rectifier 24. The machine is driven by a variable speed motor (not shown) governed by a controller 25 operated through reduction gearing. 26 by a small auxiliary three-phase motor 27. The coils 21, 22, 23 operate relay switches 21S, 22S, 23S at progressively increasing currents. These switches in the operated position engage contacts 21C, 22C, 23C, the switch 21S also engaging a contact 21D in the normal position. The auxiliary motor 27 has a starter comprising a "slow-down" switch 28 and a "speed-up" switch 29 which cause the motor to turn the controller 25 in a direction to slow down or speed up the driving motor. The switches 28, 29 are operable by relay coils 28C, 29C, the coil 28C being connected through the contacts 21C, 22C, 23C and the switches 21S, 22S, 23S with a rotary timing switch 31. The coil 29C is connected with the timing switch 31 through the contact 21D and the switch 21S. The rotor of the timing switch 31 is rotated by the machine or its driving motor so that it makes one revolution in the time taken by the entering part of the fabric 12 to reach the roller 13. The rotor has a contact segment 34 co-operating with brushes 35 ... 40 connected as shown. The rotor is mounted on a shaft 44, the brushes 35, 27, 39 being mounted on a stationary member 47, Fig. 5. The brushes 36, 38, 40 are secured to a member 47A which is angularly adjustable with respect to the member 47 by means of a weighted arm 49 which rests on a cam so arranged that the setting of the member 47A and the brushes 36, 38, 40 varies with the setting of the controller 25. The duration of the period during which each pair of brushes is bridged by the segment 34 is thereby lengthened or shortened in relation to the speed of the machine. Instead of regulating the drying by varying the speed of the fabric through the heater, the intensity of the heat applied to the fabric may be varied by substituting a heat regulator for the speed controller 25. In drying machines in which the fabric passes round large drums, one of the drums may be used as an electric contact, or two longitudinally spaced drums may be used as contacts at greatly different potentials.