Patent GB-779183-A (GB)
Title: Improvements in or relating to scrapers particularly for rocking centrifugal hydroextractors
IPC: B04B11/04
Filed: 1955-10-10
Abstract: 779,183. Centrifugal strainer separators. OFFICINE MECCANICHE E FONDERIE A. BOSCO SOC. PER AZIONI. Oct. 10, 1955 [Oct. 13, 1954 ; Sept. 14, 1955], No. 28768/55. Class 46. A mechanically operated scraper for removing sugar &c. from a cylindrical-basket rocking centrifugal hydroextractor comprises a scraper for scraping and emptying the basket, the scraper in its inoperative position lying outside the basket and above the cover thereof, means for rotating the scraper horizontally and for moving it both in its operative position and during its return to its starting or inoperative position, a support for the above-mentioned means, for the horizontal revolution and vertical displacement of the scraper, and means for previously setting and controlling the starting, the duration and the end of the operative emptying period. An outer casing 4, Fig. 5, having a cover comprising two semicircular leaves 40 connected by links to open and close simultaneously, encloses a cylindrical basket 2, rotated by a shaft 1. A support 5 mounted on the casing by a vertical leg has a horizontal arm 6, Fig. 1, supporting a vertical guide tube 17 and bored to receive a rotatable ring 7, Fig. 3, keyed to a vertical cylinder 14 carrying a scraper 16. A stationary piston 21 divides the cylinder 14 into upper and lower chambers X, y, fed with compressed air through passages p, o respectively in the rod of the piston 21, the rod being formed by concentric tubes 22, 23. The scraper 16 normally rests above the basket 2 and casing 4 whence it moves horizontally to be over the normally covered opening in the top of the casing, downwards to enter the basket and then horizontally to effect the scraping during a further vertical motion, the movements being reversed to return it to its initial position. To control these movements, a wheel secured to the upper end of the cylinder 14 runs in a groove 26 in the guide tube 17, the groove having a horizontal extension 27 at its upper end and a vertical part 28 having at its lower part a wider portion 29 providing a horizontal shoulder 31 against which a pawl 30 directs the wheel. A piston 38 in a horizontal cylinder 11 turns the ring 7 and cylinder 14 to effect the horizontal movements of the scraper, the piston being actuated by compressed air drawn from a reservoir 34 and controlled by a device 35 which times the opening of the cover 40, the movements of the scraper and the closing of the cover. The chamber X above the piston 21 is always open to the reservoir 34 through the line p to hold the cylinder 14 in its raised inoperative position i.e. with the guide wheel at the top of the groove 26 where the cylinder 11 and piston 38 keep it at the end of the horizontal part 27. On starting the control 35, which may be supplemented or overridden by a hand control 36, compressed air flows through the control along a line a, through the hand control 36 and a line f, h to a distributer valve 33 which directs it to the rear chamber v of the cylinder 11 to rotate the cylinder 14 and bring the guide wheel over the vertical part 28 of the groove 26. At the end of its stroke, the piston 38 in the cylinder 11 actuates a slide valve 71 permitting the compressed air to flow along a line r, q, o through the piston 21 to the lower chamber y of the cylinder 14 to lower it until it is within the basket when the pawl 30 directs it along the shoulder 31 before it continues its vertical scraping movement. At the end of this movement the piston 38 moves it horizontally beneath the vertical part 28 of the groove, the chamber y is opened to exhaust and compressed air supplied through the tube p to raise the cylinder 14, the pawl 30 yielding to give it passage.