Abstract:
The invention relates to a device for distributing a material in a molten state, said device comprising a swinging chute ( 16 ) supported so as to be capable of swinging about a substantially horizontal swinging axis ( 25 ), and a driving group ( 40 ). The latter comprises gear motor group ( 42 ), a drum winch ( 44 ) driven by the gear motor group ( 42 ), and at least one cable segment ( 50, 50 ′) that can be both wound on or unwound from said drum. One end of the cable segment ( 46, 50, 50′ ) is attached to the swinging chute ( 16 ) at a distance L from the swinging axis ( 25 ) thereof so as to apply a swinging momentum to said swinging chute ( 16 ).

Description:
TECHNICAL FIELD 
     The present invention relates to a device for distributing a molten material having a tilting runner supported so as to be capable of tilting about a substantially horizontal tilt axis. Such a device is used in particular for distributing liquid iron flowing a through a casting runner of a casting floor of a blast furnace casting bay to two torpedo cars or two ladles which are awaiting beneath the casting floor. 
     BACKGROUND 
     U.S. Pat. No. 3,792,850 describes such a device. The tilting runner comprises a supporting cradle, which is supported with the assistance of two supporting trunnions so as to be capable of tilting about a horizontal tilt axis and a runner element with two opposing discharge spouts which is positioned interchangeably in the supporting cradle. A supporting cradle drive unit comprises a motor reducer unit with a crank. This crank is connected via a connecting rod to a lever arm of the supporting cradle. 
     Document KR20040046395 discloses a tilting runner in which the motor reducer unit is coupled, without an intermediate connecting rod/crank, to one of the two trunnions of the supporting cradle. 
     A drawback shared by these two tilt mechanisms with a motor reducer unit is that, given the large weight of the tilting runner, the levels of torque output by the reducer must be relatively high, which entails a large and therefore costly motor reducer unit. One advantage of a drive unit with a motor reducer unit resides in the fact it is possible to provide the reducer with a second input shaft connected to a hand wheel which makes it possible to tilt the tilting runner manually in the event of a problem with the motor of the motor reducer unit or with its power supply. However, this second input shaft entails an additional gear train with a very high transmission ratio to allow the tilting runner to be tilted manually, so still further increasing the cost of the motor reducer unit. 
     There are also tilting runners which have a supporting cradle drive unit which comprises a hydraulic or pneumatic piston-cylinder unit connected to a lever arm of the supporting cradle. However, a hydraulic piston-cylinder unit of large diameter, which requires elevated flow rates of hydraulic oil under high pressure to function, is inadvisable in the immediate vicinity of large quantities of liquid iron (fire hazard). A pneumatic piston-cylinder unit, on the other hand, has the disadvantage of not permitting reliable adjustment of the angle of inclination of the tilting runner. Furthermore, the solutions with a hydraulic or pneumatic piston-cylinder unit have the disadvantage of not providing the possibility of manually tilting the tilting runner in the event of a problem with the supply of hydraulic or pneumatic fluid. 
     BRIEF SUMMARY 
     The invention proposes a device for distributing a molten material having a tilting runner equipped with a simple and inexpensive drive unit which nevertheless ensures safe and reliable tilting of the tilting runner. 
     The present invention further proposes a device for distributing a molten material comprising in known manner per se: a tilting runner supported so as to be capable of tilting about a substantially horizontal tilt axis; a drive unit having a motor reducer unit and a force transmission means connecting the motor reducer unit to the tilting runner, so as to transmit to the latter a tilt moment about the tilt axis thereof. According to a novel aspect, the force transmission means comprises a drum winch driven by the motor reducer unit and at least one length of cable which winds onto the drum or unwinds from the latter; one end of said length of cable being attached to the tilting runner at a distance L from the tilt axis thereof, so as to be capable of applying the tilt moment to the tilting runner. It will be understood that the force transmission means essentially comprises simple elements, which are mostly commercially available. Furthermore, the torque required at the output of the motor reducer unit to cause the drum winch to operate is relatively low, such that a small and therefore inexpensive motor reducer may be used. Most frequently, the reducer need only comprise a gear train made up of a worm screw and a paired worm wheel and may be self-locking when stationary. It will also be understood that cable transmission allows great freedom with regard to the location of the drive unit, which may for example be positioned on the casting floor, in a cabinet adjacent to the tilting runner, or even beneath the tilting runner. Furthermore, apart from the cables, there is no mechanical connection between the drive unit and the tilting runner, which facilitates assembly and disassembly of the drive unit and/or of the tilting runner. 
     In a first variant embodiment, the force transmission means comprises a single length of cable which is capable of transmitting to the tilting runner a tilt moment in a first direction to move it from a first position into a second position, when said length of cable is wound onto the drum; and the tilting runner is balanced so as to return from the second position to the first position when the cable is unwound from the drum. In other words, the drive unit serves solely to generate the torque to tilt the tilting runner in one direction. Tilting of the tilting runner in the opposite direction is effected thanks to the force of gravity acting directly on the tilting runner. 
     In a preferred variant embodiment, the force transmission means comprises a first length of cable and a second length, one end of the first length of cable being attached to the tilting runner so as to be capable of applying to the latter a tilt moment in a first direction, when said first length of cable is wound onto the drum; and one end of the second length of cable being attached to the tilting runner so as to be capable of applying to the latter a tilt moment in a second direction, when said second length of cable is wound onto the drum. In this variant embodiment, the drive unit serves to generate the torque for tilting the tilting runner in two directions. It will be understood that this variant embodiment makes it possible to balance the tilting runner such that it is at equilibrium between a first position, in which it discharges the molten material on the left-hand side, and a second position, in which it discharges the molten material on the right-hand side. Consequently, in this equilibrium position, no forces apply to the drive unit. 
     The device advantageously comprises a first limit of travel end stop defining a first extreme inclination position for the tilting runner, and a second limit of travel end stop defining a second extreme inclination position for the tilting runner. These limit of travel end stops provide a safety stop for the tilting runner. 
     In order to prevent a cable from breaking when the tilting runner is stopped in its tilt motion by a limit of travel end stop or by another rigid obstacle, an attachment point is provided on the tilting runner for the cable which is advantageously formed by an attachment system with prestressed springs. While the tension in the cable remains less than the spring prestressing force, the springs do not compress, and the attachment system provides an immobile attachment point for the rope. However, if the tilting runner is stopped in its tilt motion by a limit of travel end stop or another rigid obstacle, the force in the length of cable exceeds the spring prestressing force. The springs then compress and the attachment point yields proportionally to the modulus of the tensile force, so limiting the tension in the cable and avoiding premature breakage thereof. 
     The tilting runner advantageously comprises two lever arms, the end of the first length of cable being attached to the first lever arm and the end of the second length of cable being attached to the second lever arm. These two lever arms are preferably symmetrical relative to a vertical plane passing through the tilt axis, and each lever arm advantageously bears a cable guide in the shape of an arc of a circle, the centre of curvature of which is located on the tilt axis. Thanks to these two cable guides, the lengthening of one length of cable is substantially equal to the shortening of the other length of cable, which permits straightforward winding and unwinding of the two lengths of cable on a single drum. 
     A tensioning weight is advantageously associated with each length of cable so as to keep the latter taut around the drum when the length of cable is not transmitting any tensile force. 
     In a first variant embodiment, the tilting runner comprises a runner element with two opposing discharge spouts which is supported with the assistance of two supporting trunnions so as to be capable of tilting about the horizontal tilt axis. 
     In a preferred variant embodiment, the tilting runner comprises a supporting cradle, which is supported with the assistance of two supporting trunnions so as to be capable of tilting about the horizontal tilt axis, and a runner element with two opposing discharge spouts which is positioned interchangeably in the supporting cradle. This variant with a supporting cradle allows the runner element to be replaced quickly and easily. 
     The motor reducer unit and the drum winch are preferably arranged beside the tilting runner and are advantageously separated from the latter by a protective wall. 
     A preferred embodiment furthermore comprises a limit of travel cam attached to the tilting runner, a device for detecting certain predefined positions of the limit of travel cam and a circuit for stopping the motor reducer unit when such a predefined position is detected. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other distinctive features and characteristics of the invention will be revealed by the detailed description of some advantageous embodiments given below by way of example, with reference to the appended drawings, in which: 
         FIG. 1 : is a vertical section, along section line  1 - 1  indicated on  FIG. 2 , of a device for distributing a molten material according to the invention; 
         FIG. 2 : is a horizontal section along section line  2 - 2  indicated on  FIG. 1 ; 
         FIG. 3 : is a vertical section along section line  3 - 3  indicated on  FIG. 2 ; 
         FIG. 4 : is a partial section showing the detail indicated by a circle  4  in  FIG. 1 ; and 
         FIG. 5 : is a section showing the detail indicated by a circle  5  in  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION 
     The appended figures show a device according to the present invention, which is used, by way of example, for distributing liquid iron  8  flowing through a casting runner  10  of a casting floor  12  of a blast furnace casting bay to two torpedo cars  14 ,  14 ′, which are awaiting beneath the casting floor  12 . This device comprises a tilting runner, denoted overall by the reference  16 , which is advantageously composed of a supporting cradle  18  and an interchangeable runner element  20 . 
     The supporting cradle  18  is equipped with two trunnions  22 ,  22 ′, which are accommodated in lateral bearings  24 ,  24 ′, such that the supporting cradle  18  is capable of tilting about a tilt axis  25 . The interchangeable runner element  20  forms a discharge spout  28 ,  28 ′ for the iron at each of the two ends thereof. It is placed from above in the supporting cradle  18  and is equipped with feet  26 ,  26 ′, which wedge it on the supporting cradle  18  and immobilise it when the latter tilts. 
     In  FIG. 1 , the tilting runner is shown in the resting (or waiting) position, in which the runner element  20  is substantially horizontal. It will be noted that the tilting runner  16  assembly is advantageously balanced so as to be at equilibrium in this resting position, i.e. no moment need be applied to keep the runner element  20  substantially horizontal. By applying a tilt moment to the tilting runner  16 , it is however possible to cause the supporting cradle  18  to tilt in the direction of the arrow  30  to bring the runner element  20  into an inclined position for discharge into the torpedo car  14  (as suggested by the broken lines in  FIG. 1 ), and in the direction of the arrow  30 ′ to bring the runner element  20  into an inclined position for discharge into the torpedo car  14 ′. 
     Reference sign  32  denotes a first end stop borne by a sub-structure  34  so as to cooperate with a first counter end stop  32 ′ on the supporting cradle  18  in order to define an extreme inclination position of the runner element  20 , when the supporting cradle  18  is caused to tilt in the direction of the arrow  30 . Reference sign  36  denotes a second end stop borne by a sub-structure  34  so as to cooperate with a second counter end stop  36 ′ on the supporting cradle  18  in order to define an extreme inclination position of the runner element  20 , when the supporting cradle  18  is caused to tilt in the direction of the arrow  30 ′. 
       FIGS. 2 and 3  show a particularly advantageous drive unit  40  associated with the tilting runner  16 . This drive unit  40  comprises a motor reducer unit  42  which drives a drum winch  44 . A cable, denoted overall by the reference sign  46 , winds onto and unwinds from the winch, said cable making it possible to apply to the tilting runner  16  a tilt moment about the tilt axis  25  thereof. The drum winch  44  may most often be a standard commercially available model. The motor reducer unit  42  may comprise an electric, hydraulic or pneumatic motor coupled to the reducer. The reducer of the motor reducer unit  42  may be relatively small. Most frequently, it is sufficient for it to comprise a single gear train essentially composed of a worm screw and a paired worm wheel. This worm screw gear train is advantageously dimensioned so as to be self-locking when stationary. It should also be noted that the motor reducer unit  42  and the drum winch  44  are, in the embodiment shown in the figures, arranged beneath the casting floor  12 , beside the tilting runner  16 , and separated from the latter by a protective wall  48 . 
     In the preferred embodiment shown with the assistance of the figures, the cable  46  comprises a first length of cable  50 , equipped with an end  52  attached to the tilting runner  16 , at a distance L from the tilt axis  25  thereof, so as to be capable of applying to the latter a tilt moment in the direction of the arrow  30 ′, and a second length of cable  50 ′, equipped with an end  52 ′ attached to the tilting runner  16 , at a distance L from the tilt axis  25  thereof, so as to be capable of applying to the latter a tilt moment in the opposite direction indicated by the arrow  30 . Between the first length of cable  50  and the second length of cable  50 ′, the cable  46  forms several turns around the drum winch  44 . In order to avoid slippage between the drum winch  44  and the cable  46 , the latter may be attached to the drum winch  44 , such that the length of cable  50  can wind up on one side of this attachment and length of cable  50 ′ can wind up on the other side of this attachment point. Alternatively, each length of cable  50 ,  50 ′ may of course be attached individually to the drum winch  44 . 
     In  FIG. 1 , it can be seen that the supporting cradle  18  comprises two lever arms  54 ,  54 ′ which are symmetrical relative to a vertical plane passing through the tilt axis  25 . The first lever arm  54  serves as the attachment point for said first end  52  of the first length of cable  50 , and the second lever arm  54 ′ serves as the attachment point for said second end  52 ′ of the second length of cable  50 ′. 
     In  FIG. 1 , it can also be seen that each lever arm  54 ,  54 ′ bears a cable guide  56 ,  56 ′ in the shape of an arc of a circle, the centre of curvature of which is located on the tilt axis  25 . Reference numerals  58 ,  58 ′ denote return pulleys arranged above the cable guides  56 ,  56 ′, symmetrically relative to a vertical plane passing through the tilt axis  25 . These return pulleys  58 ,  58 ′ serve respectively to guide the length of cable  50  and  50 ′, beneath the casting floor  12  to above the drum winch  44 . Reference numerals  59 ,  59 ′ denote return pulleys arranged above the drum winch  44  for guiding the length of cable  50  and  50 ′ respectively onto the drum winch  44 . 
     When the first length of cable  50  winds around the drum winch  44 , the second length of cable  50 ′ unwinds from the drum winch  44  and vice versa. Thanks to the two cable guides  56 ,  56 ′ in the shape of an arc of a circle, the centre of curvature of which is located on the tilt axis  25 , the lengthening of a length of cable  50  is substantially equal to the shortening of the other length of cable  50 ′, which permits straightforward winding and unwinding of the two lengths of cable on a single drum. 
       FIG. 5  shows a preferred attachment of the first end  52  of the length of cable  50  to the lever arm  54  (the attachment of the second end  52 ′ of the length of cable  50 ′ to the lever arm  54 ′ is preferably identical). Reference  60  denotes overall an attachment system with prestressed springs  62 , which will now be described in greater detail. This attachment system comprises a tube  64  equipped with a collet  66  at one end and with a thread  68  at the other end. The tube  64  is accommodated in a hole  70  of a base  72  of the lever arm  54 , with its collet  66  resting on the outer surface  74  of the base  72 . The springs  62 , which are advantageously spring washers (Belleville springs), are slipped onto the tube  64 , from the opposite end to the hole  70 . A plate  76  is screwed onto the thread  68 , so as to compress the springs  62  between its inner face  78  and the inner face  80  of the base  72 . In this manner, a predefined prestressing force is applied to the springs  62 , which force substantially corresponds to the maximum tensile force in the length of cable  50  which is to be anticipated during tilting operation of the tilting runner  16 . 
     The length of cable  50  is attached to an attachment rod  86  which has a threaded end  88  which passes through the tube  64 . A tension adjustment nut  90  screwed onto this threaded end  88  forms an adjustable support, with which the attachment rod  86  rests against the lower end of the tube  64 . It is accordingly known to tension the length of cable  50  with the assistance of this tension adjustment nut  90 . Once the tension in the length of cable  50  has been adjusted, the nut  90  is locked with the assistance of a locknut  92 . 
     While the tension in the length of cable  50  remains less than the spring  62  prestressing force, the springs  62  do not compress, and the tube  64  forms an immobile support for the attachment rod  86 . However, if the tilting runner  16  is stopped in its tilt motion by the end stop  32 ′ or by another rigid obstacle, the force in the length of cable  50  exceeds the spring  62  prestressing force, the springs  62  compress, and the tube  64  is drawn by the attachment rod  86  in the direction of the arrow  94 , proportionally to the modulus of the tensile force, so limiting the tension in the length of cable  50  and avoiding premature breakage thereof. 
       FIG. 4  shows a tensioning weight  96  advantageously associated with the length of cable  50  so as to keep the latter taut around the drum winch  44 . This comprises, for example, a lead cylinder provided with a through-channel  98  for the length of cable  50  and which rests on a stop  100 , so as to exert tension on the length of cable  50  in the direction of the first end  52  thereof. It should be noted that a similar tensioning weight  96 ′ is advantageously also associated with the length of cable  50 ′. 
     On  FIGS. 2 and 3 , reference numeral  102  denotes overall a limit of travel detection system. This system  102  comprises a limit of travel cam  104  integral with the trunnion  22  and a detection device  106  which makes it possible to detect certain predefined positions of said limit of travel cam, for example with the assistance of mechanical or magnetic contacts or of inductive, capacitive or optical sensors. An electrical system (not shown) may then be used to stop the motor reducer unit when such a predefined position is detected. 
     On  FIG. 3 , reference  110  denotes a hand wheel which makes it possible to tilt the tilting runner  16  manually in the event of a problem with the motor of the motor reducer unit  42  or with its power supply. It will be understood that, as a consequence of the large lever arms involved in the transmission of the tilt moment to the tilting runner  16 , it is possible to have a relatively small reducer to transmit the manual force to the drum winch  44 .