GB709548A - Electrically heated screen construction - Google Patents

Abstract

709,548. Sieves. HANNON, T. W. Oct. 13, 1952 [Jan. 14, 1952; June 4, 1952; July 10, 1952], No. 25606/52. Class 117 In an electrically heated screen Figs. 2 and 3, the screen deck 23, which may be made of steel or stainless steel wire, is mounted in a frame comprising side members 12a and 12b which are connected by a bridge member 16 which carries an electrical vibrator 51 connected to the centre of the screen 23. A member 19a is mounted by means of an insulated hinge 20 on the side member 12a and carries a longitudinally extending bus bar 22a which is provided with a V- shaped tongue fitting into a bar 24a attached to the sifting element 23. A similar member 19b is mounted on the side member 12b. Tension is applied to the sifting element by means of bolts 34 and nuts 37 which are insulated from the bus bars by sleeves 30. Conductors 55a, 55b connect the bus bars to a low voltage supply. Figs. 10 and 11 show an arrangement in which the frame mounting the screen is vibrated. The frame comprises side plates 310a, 310b, carrying an upper screen deck 311 and a lower deck 312 which are supported in an arched position by bars 314 having moulded rubber strips 315 on their top edges to prevent chafing and provide electrical insulation, the bars 314 being supported on the transverse beams 316 attached to the side plates. Longitudinal members 320 having an out-turned flange 322, which is covered with an insulating material 323, tension the screen cloth, the tension being adjusted by spring-loaded nuts 328. Contact bars 331 extend the length of the screen and are carried on angles 319 attached to the side plates, being insulated from the angles by fibre strips 334, and bus bars 337, 338, are connected to the respective bars 331. The bus bars are insulated from each other and from the side plate by fibre sheets 352, 353, and are secured by a bolt 354 provided with an insulating sleeve. They are carried in the bottom of the sieve frame in a channel member 356 which is lined with fibre strips, and are connected by cables 351 to the supply. A number of bus bars may be connected to each contact bar to ensure uniform heating.