Patent GB-934441-A (GB)
Title: Improvements in or relating to apparatus for detecting and recording stockrod movements in shaft furnaces and the like
Inventor: KANE JOHN BRADLEY
IPC: F27B1/28
Filed: 1959-02-07
Abstract: 934,441. Recording-apparatus. ASHMORE, BENSON, PEASE & CO. Ltd. Feb. 5, 1960 [Feb. 7, 1959], No. 4369/59. Class 106 (4). Apparatus for detecting and recording stockrod movement in a shaft furnace, such as a blast furnace or kiln, comprises means responsive to the magnitude and direction of movement of a stockrod 14 in the furnace 11 and driving a pen 24 over a moving chart 23, and means responsive to the speed and direction of travel of the stockrod 14 for selectively causing another pen 25 to be driven in response only to the magnitude of movement of the rod 14 in a downward direction after it has engaged the burden 13 in the furnace 11. A winch drum 17 moves with the stockrod 14 being driven by a motor 18 to hoist the rod to a " zero " position when a valve 12 is opened to admit a fresh charge and reversing against the action of a brake 20 when the rod falls under its own weight into contact with the burden and thereafter as the level of the burden drops. Thus an electric correspondence control system, with selsyn transmitter 27 and receiver 28 causing the pen 24 to follow the movement of the drum 17, gives a record of the movement of the top 15 of the burden. The pen 25 is driven by the control system through a clutch 31 which is operative only while the rod 14 is in contact with the top 15 and a counter 60 may register the total travel of the pen 25. A reversing unit 34 changes the direction of movement of the pen 25 each time it reaches an extremity of its travel. A suitable form of motor 18 is a slip-ring induction motor with its stator connected to a polyphase alternating current supply so that the rotor operates the winch to hoist the rod, whilst a measure of speed control is obtained by varying resistors connected to the rotor circuit through slip-rings. With a larger resistor in the rotor circuit the motor may operate as a brake while the rod descends and the change in the voltage appearing across the slip-rings gives a measure of the speed of movement of the rod so that the change of speed as the rod engages the top 15 of the burden in the furnace can be detected by a voltage sensitive relay. Auxiliary contacts in combination with contacts on the voltage sensitive relay can serve to provide a control responsive to both speed and direction of movement of the rod and control the connection and disconnection of the second pen. In other embodiments the pens are moved by solenoid-operated pawl and ratchet devices fed with pulses generated in accordance with the travel of the stockrod. In one case (a) a multisegment commutator associated with the winch is arranged upon rotation to alternatively connect and disconnect a pair of brushes controlling an impulse generator. In another (b) alternate magnetic and non-magnetic segments round a disc affect pick-up coils, one of which feeds signals to a pulse generator. Alternatively (c) a cam-operated switch associated with the winch generates the pulses. In these three cases the means responsive to the speed of the rod are respectively (a) two slow release relays whose circuits are completed alternately by one of three brushes being connected alternately to the other two by the commutator segments; (b) a pair of pick-up coils circumferentially spaced around the disc so that relative to the magnetic segments they are effectively in quadrature and the direction of rotation can be detected from the phase relationship of the e.m.f.s induced in the two coils; (c) a second cam-operated switch associated with the winch with contact sets operated alternately and connected in series respectively with two slow release relays.