Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
  • B22D11/16—Controlling or regulating processes or operations
  • B22D11/20—Controlling or regulating processes or operations for removing cast stock
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
  • B22D11/16—Controlling or regulating processes or operations
  • B22D11/161—Controlling or regulating processes or operations for automatic starting the casting process

Definitions

• the metal from the ladle is poured into the distributor. Then the stopper is opened so that the metal fills the ingot mold by flowing through the nozzle. When the metal reaches a predetermined level in the mold, the dummy is driven downwards, to start the extraction of the cast product, at least partially solidified in contact with the cooled walls of the mold.
• the reaction time of the stopper rod cannot be reduced sufficiently to completely avoid the aforementioned problem.
• the inertia of the metal flow and that of the stopper control means causes level fluctuations which can last for a certain time before the regulation and therefore the level stabilize and the casting becomes regular.
• Another problem which arises is to arrive at determining the moment of the effective start of the casting, that is to say the instant when the metal contained in the distributor begins to flow when the opening of the stopper is controlled. This problem is also linked to that of being able to control the rise in the level in the ingot mold, this level not being detectable during a large part of the filling, as we have seen previously.
• the only way to control this level rise is therefore to act on the flow of metal flowing from the distributor, which depends on the exact position of the stopper rod.
• the position of the stopper is conventionally determined by a measuring device located on the stopper control means and not on the stopper itself. It follows that the indication given by these measuring means is not exactly representative of the position of the stopper itself, this being due in particular to the inevitable clearances of the means of mechanical connection of the stopper to its control means . It follows that not only is there a time lag between the command to open the stopper rod and the start of the actual opening, and therefore the start of the flow of metal, but also, thereafter, the The indication of the position of the stopper rod is not an exact reflection of its actual position, which determines the metal flow rate. However, it is only by knowing the precise instant of the start of casting, and of the flow rate, that the level in the ingot mold can be determined precisely during filling.
• this process is characterized in that, before starting the casting: a) the stopper rod is placed on its seat under the sole effect of its own weight, the control cylinder being inactive and in a position of initialization defined by the position of the stopper rod, b) the said initialization position of the control cylinder is determined, c) the control cylinder is actuated in the closing direction to push the stopper rod on its seat, d) it is filled the distributor with the liquid metal, e) the control cylinder is actuated to bring it into a controlled over-closing position defined by a predetermined distance from the position of the control cylinder relative to the initialization position, and, to start casting: f) the control cylinder is actuated in the opening direction according to a predefined law imposed on the displacement of the control cylinder as a function of time, the instant of start of casting being determined From this law, by calculating with the law the time taken to that the control cylinder passes from the over-closing position to the initialization position, g) and
• the method according to the invention makes it possible to precisely determine the moment when the molten metal will be able to begin to flow between the stopper rod and its seat. This moment is therefore just when the distaff leaves his seat.
• the controlled over-closing position is defined by a preset distance considered from the position of the control jack when it just causes the stopper to detach from its seat, that is to say the initialization position.
• step f This law will therefore allow, at the beginning of step f), to ensure a displacement of the jack, without there being proportional displacement of the stopper rod, this displacement of the jack corresponding in a way to a relaxation of the stresses generated by the support effort of the stopper rod on its seat.
• step c) the stopper rod is pushed on its seat until the pushing force exerted by the control means reaches a predetermined value.
• a level regulation is brought into service which ensures level regulation as soon as the metal level comes close to the nominal level.
• the level regulation well known in continuous casting installations, is therefore put into service well before the metal level can be detected by the sensor, conventionally used in regulation systems.
• the regulation is however saturated so as to avoid that it tends to cause an additional opening of the stopper rod (which would normally be the case since the metal level is then largely below the normal level).
• the regulation circuits are already in service before the sensor detects the metal cast in the mold, the regulation intervenes without delay as soon as the metal level is detected. It follows that the reaction, caused by said regulation when the cast metal comes close to the nominal level, is less sharp and does not generate an abrupt displacement of the stopper rod or an abrupt variation in the extraction speed.
• FIG. 1 is a schematic view of an installation for continuous casting of steel in an ingot mold
• the installation also comprises, in a manner known per se, an ingot mold 20 whose walls are vigorously cooled to cool and solidify the molten metal poured into the ingot mold by the nozzle 4.
• the metal at least partially solidified in the form, for example, of a slab 21 is extracted from the mold downwards, by means of extraction rollers 22 driven in rotation by motors not shown.
• control cylinder must obviously understand not only a conventional cylinder comprising a rod movable in translation in a cylinder body, such as the cylinder 7 shown in Figure 1, but also any other actuator that can perform the same function of displacement of the stopper rod.
• the graph in FIG. 2 shows, by way of example of the method according to the invention, the variations in the position d of the jack 7 as a function of time t, from an instant situated before the starting process, until the arrival in normal casting regime.
• the trace 31 corresponds to the initialization position "O" of the control cylinder, that is to say the measured position of the cylinder rod when the stopper 5 rests under the effect of its own weight on its seat 6
• the jack is then not subjected to any pressure by the solenoid valve 13, the position of the rod then being solely determined by the position of the stopper 5.
• the weight of the stopper and that of the actuator rod exert downward efforts on the lever 8, and that, consequently, the inevitable clearances at the level of all the articulations are situated upwards for the articulations 51 and 61 of the stopper rod and the cylinder rod on the lever, as well as for the pivot articulation 9 of the lever on one installation.
• This position will subsequently be considered as the starting point for controlling the actuator under the imposed opening law already mentioned.
• the metal flow can therefore be different from the nominal flow under which the metal will flow from the distributor in the mold after the start of the rollers d 'extraction. It is only when the level of metal in the ingot mold arrives near the level detector 12 that the level regulation, of a type known per se, takes over to control the jack 7, as well as possibly the speed of the extractor rollers 22, to adapt the flow rate at the extraction speed, so as to maintain a substantially constant level of metal in the mold, as is well known.
• the invention is not limited to the starting process which has just been described only by way of example.
• the method according to the invention can advantageously be implemented in continuous casting installations between cylinders.
• the position measurements can be carried out by any other measuring means capable of precisely determining the position of the stopper control means.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Continuous Casting (AREA)
• Casting Support Devices, Ladles, And Melt Control Thereby (AREA)
• Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)
• Treatment Of Steel In Its Molten State (AREA)
• Examining Or Testing Airtightness (AREA)
• Forging (AREA)
• Pinball Game Machines (AREA)

Applications Claiming Priority (3)

Publications (2)

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Family Applications (1)

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Families Citing this family (7)

Family Cites Families (12)

• 1997
  • 1997-07-16 FR FR9709241A patent/FR2766113B1/fr not_active Expired - Fee Related
• 1998
  • 1998-01-07 UA UA2000020805A patent/UA59406C2/uk unknown
  • 1998-07-01 PT PT98935068T patent/PT998360E/pt unknown
  • 1998-07-01 EP EP98935068A patent/EP0998360B1/de not_active Expired - Lifetime
  • 1998-07-01 CA CA002296743A patent/CA2296743C/fr not_active Expired - Fee Related
  • 1998-07-01 KR KR10-2000-7000453A patent/KR100538966B1/ko not_active Expired - Fee Related
  • 1998-07-01 US US09/462,154 patent/US6374902B1/en not_active Expired - Fee Related
  • 1998-07-01 AT AT98935068T patent/ATE224783T1/de not_active IP Right Cessation
  • 1998-07-01 WO PCT/FR1998/001401 patent/WO1999003619A1/fr not_active Ceased
  • 1998-07-01 CZ CZ200041A patent/CZ288868B6/cs not_active IP Right Cessation
  • 1998-07-01 ES ES98935068T patent/ES2184303T3/es not_active Expired - Lifetime
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  • 1998-07-01 BR BR9811792-0A patent/BR9811792A/pt not_active IP Right Cessation
  • 1998-07-01 RO ROA200000044A patent/RO120463B1/ro unknown
  • 1998-07-01 DK DK98935068T patent/DK0998360T3/da active
  • 1998-07-01 DE DE69808299T patent/DE69808299T2/de not_active Expired - Fee Related
  • 1998-07-01 AU AU84448/98A patent/AU727961B2/en not_active Ceased
  • 1998-07-01 PL PL98338193A patent/PL186661B1/pl not_active IP Right Cessation
  • 1998-07-01 TR TR2000/00104T patent/TR200000104T2/xx unknown
  • 1998-07-01 SK SK32-2000A patent/SK285291B6/sk not_active IP Right Cessation
  • 1998-07-01 CN CN98807295A patent/CN1086614C/zh not_active Expired - Fee Related
  • 1998-07-01 MX MXPA00000553A patent/MXPA00000553A/es not_active IP Right Cessation
  • 1998-07-01 JP JP2000502900A patent/JP4224840B2/ja not_active Expired - Fee Related
  • 1998-07-09 ZA ZA986185A patent/ZA986185B/xx unknown
  • 1998-09-03 TW TW087114677A patent/TW375540B/zh not_active IP Right Cessation

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