GB1469411A - Operating mechanism for slidable gates and flow- controlling method - Google Patents

Abstract

1469411 Sliding gate valves for metallurgical vessels USS ENG & CONSULTANTS Inc 1 March 1974 [1 March 1973] 9446/74 Heading F4B A bottom-pour metallurgical vessel comprises a frame 21 attached to the bottom of the vessel 12 by a mounting plate 14, means on the frame for slidably supporting blank and orifice gates 38, 39 for movement between a ready position, a slow-motion region under the vessel outlet and a removal position beyond the slow-motion region, the slow-motion region being from the position where the outlet is partly open to where it is fully open, main and auxiliary drive means being carried at opposite ends of the frame, the main drive being adapted to push a gate from the ready position to the slow-motion region and to displace a gate already in the slow-motion position into the removal position, the auxiliary drive serving to retard the rate of movement of a gate as it reaches the slow-motion region so that the gate can be moved rapidly from the ready position to the slow-motion region and thereafter slowly under close control and in either direction. The top plate 22 of the frame has a central opening 41 to receive the stationary refractory top plate 42. This plate is readily replaced when necessary when the frame 21 is removed from the mounting plate 14 by withdrawal of the pins 37 normally engaging lugs 19 standing down from plate 14. The main drive means is a hydraulic cylinder 46 having a piston 48, piston rod 49 and ram 50. The auxiliary drive consists of cylinder 47, piston 51, rod 52 and ram 53. Each cylinder has a hydraulic line 54, 56 connected to the back end and a compressed air line 55, 57 connected to the front end. The sliding gates are supported on side levers 60, Fig. 4 arranged to rock about central bolts 63. Springs 65 bear down on the outside edges of the levers so that the inside edges press the sliding gates upwardly against the top plate 42. The pouring tube holding plate 34 is held pressed upwardly against the gates by similar spring- loaded levers 61. The springs are cooled by air blown through nozzles from bores 17 in the mounting plate 14. The blank gate 38 is positioned under the top plate 42 before filling with molten metal. The main ram 50 is fully retracted and the orifice gate 39 is inserted sideways into the slideway through an opening provided for the purpose. The cylinder 46 is then operated to push the gates to the right so that the orifice gate comes under the opening 43 in the top plate 42. Piston 51 of the auxiliary cylinder 47 is retracted by this movement so that at the beginning of the slow-motion region a plug 74 enters bore 75 which is connected to the cylinder 47 by a passage 76 the effective cross-section of which is adjustable by a screw 77. In the first part of the movement fluid escapes readily from cylinder 47 through the bore 75 and line 56. When the plug enters the bore the fluid can only escape via the restricted passage 75 so that the parts move slowly and close control is possible. The same arrangement also ensures slow-motion in the opposite direction under the control of the cylinder 47. The blank gate can be replaced during teeming by applying air pressure at 57 to cylinder 47 to retract the ram 53 so that the gate is free to be removed sideways and a new gate put in. Teeming is stopped by applying hydraulic pressure to the cylinder 46 to push the blank gate under the orifice 43. The orifice gate may be changed as described above or by first removing the blank gate, returning the cylinder 46 to the left-hand position, inserting a new orifice gate from the side and using the cylinder 46 to push the new and old orifice gates to the right so that the old one can be removed sideways at the blank gate position. The blank gate has a gas-permeable plug 91 supplied with gas via a circumferential channel 94. The nozzle 13 is kept clear by applying an inert gas, e.g. argon to this plug to stir the metal in the nozzle. Just before teeming oxygen may be applied instead to burn away any skin that has formed. The gases are applied via passages in the mounting plate 14, the top plate 42 and the blank gate 38. The pouring tube 98 held in position on its holding plate 34 by a U - shaped wire clip 106 passing through holes in the skirt 102 of the frame of the plate 34 and through grooves in the metal band 104 of the spout 98. The plate 34 is located by stops 112 inserted sideways through the frame. The plate is replaced by removing the stops, retracting cylinder 46, inserting a new plate to the left of the old one, operating the cylinder so that abutment 109 moves both plates to the right, the old one then being removed through a space provided for the purpose. Specifications 1,469,412 and 1,469,413 are referred to.