GB1602327A - Method and apparatus for continuous casting - Google Patents
Method and apparatus for continuous casting Download PDFInfo
- Publication number
- GB1602327A GB1602327A GB1428378A GB1428378A GB1602327A GB 1602327 A GB1602327 A GB 1602327A GB 1428378 A GB1428378 A GB 1428378A GB 1428378 A GB1428378 A GB 1428378A GB 1602327 A GB1602327 A GB 1602327A
- Authority
- GB
- United Kingdom
- Prior art keywords
- ladle
- molten metal
- valve
- drawing speed
- tundish
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
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
- B22D11/18—Controlling or regulating processes or operations for pouring
- B22D11/181—Controlling or regulating processes or operations for pouring responsive to molten metal level or slag level
Description
(54) IMPROVED METHOD AND APPARATUS FOR CONTINUOUS CASTING
(71) We, MITSUBISHI JUKOGYO KABUSHIKI KAISHA a Japanese body corporate, of 5-1, Marunouchi 2-chome, Chiyoda-ku, Tokyo, Japan, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:
The present invention relates to a method and apparatus for the control of a ladle valve during continuous casting, and more particularly, to a method and apparatus for automatically controlling the said valve so as to maintain the drawing speed of the cast product substantially constant.
In previously known methods and apparatus for controlling a ladle valve during continuous casting, manual operation of the said valve has usually been employed, although occasionally a method and apparatus in which the valve is controlled in response to the weight of a tundish monitored by means of a load cell provided in the tundish or in which the valve is controlled in response to the weight of a ladle monitored by means of a load cell provided in the ladle have been proposed.
These methods and apparatus of the prior art not only have a disadvantage in that both require a special monitoring device, but also, with regard to the principal problem in continuous casting of maintaining the drawing speed of the cast product (casting speed) substantially constant for maintaining the quality of the product, there is also the disadvantage that no provision is made for external influences such as variations of the spout or nozzle of the tundish or the like: this is due to the fact that in these methods and apparatus an indirect parameter such as the weight of a ladle or a tundish is monitored.
It is an object of the present invention to provide a method and apparatus for controlling a ladle valve during continuous casting, in which the above disadvantages in the prior art can be eliminated.
Another object of the present invention is to provide a method of controlling the valve during continuous casting, in which the solidification speed of the molten metal can be kept substantially constant by maintaining the drawing speed substantially constant thereby ensuring a uniform quality of the continuously cast product.
Yet another object of the present invention is to provide a method for automatic control of the valve during continuous casting. thereby achieving a direct saving of labour.
According to one aspect of the prevent invention there is provided a method for the control of the valve of a ladle of continuous casting apparatus during the continuous casting of a cast product, characterised by the steps of monitoring the drawing speed of the said product by detector means, subjecting the monitored drawing speed to an arithmetic processing by arithmetic means to calculate at any instant the required opening of the ladle valve in relation to the particular drawing speed at said instant, such that the pouring rate through said opening corresponds to the setting rate of the molten metal at said particular drawing speed. and maintaining the ladle valve continuously at an appropriate required opening in relation to the particular drawing speed to control the flow rate of molten metal from the said ladle to a tundish, from which molten metal is caused to flow to the mould at a rate such that it continuously corresponds to the setting rate of the molten metal.
According to another aspect of the invention, there is provided continuous casting apparatus of the kind having a ladle for molten metal connected to a tundish via a ladle valve, and a mould into which molten metal from the tundish is caused to flow at a controlled rate. characterised in that a speed detector is provided for detecting the speed of the cast product issuing from the mould, and arithmetic means are provided which are arranged to receive data from the speed detector for arithmetic processing, thereby to determine a required opening for the ladle valve, using a method according to the preceding paragraph.
The above-mentioned and other features and objects of the present invention will become more apparent from the following detailed description of a preferred embodiment taken in conjunction with the accompanying drawings, in which
Figure 1 is a schematic view of the preferred embodiment, and
Figure 2 is a diagram showing the relationship between the flow rate of molten metal from a ladle and the stroke of the ladle valve.
Referring now to Figure 1, in a continuous casting installation, molten metal (e.g. steel) contained in a ladle 1 flows into a tundish 2 through a sliding gate type ladle valve 3, the opening area of which depends upon the stroke of a piston/cylinder unit 3a connected thereto. Molten metal accumulated in the tundish 2 flows into a mould 4 through a spout or nozzle extending from the bottom of the tundish 2 at a speed proportional to the square root of the height of the molten metal within the tundish 2. In a similar manner to conventional continuous casting apparatus, the molten metal having flowed into the mould 4 is solidified into a cast product in the mould 4 which is water-cooled externally and is adapted to be drawn continuously by means of drawing rollers 5.
The present invention is characterized in that the drawing speed of this cast product is monitored by means of a speed detector 7, the monitored drawing speed is subjected to an arithmetic processing by means of an arithmetic unit 6 to determine a required opening of the ladle valve 3, and said ladle valve is always maintained at said required opening, whereby the flow rate of the molten metal from the ladle 1 to the tundish 2 can be controlled so as to maintain the drawing speed of the cast product substantially constant.
It is to be noted that the level of the molten metal within the mould is maintained substantially constant by varying the drawing speed of the cast product by means of a mould level control device 8. As the control device for the ladle valve uses a control for maintaining the drawing speed of the cast product constant, interference between the mould level control device 8 and the ladle valve control device may present a problem.
However, in this case, since the response of the mould level control device 8 is much faster than the response of the ladle valve control device, any interference between the two devices can be reduced to insignificant proportions by retarding the response of the ladle valve control device. Furthermore, since the mould level is maintained substantially constant by means of the mould level control device 8, provided that the response is fast enough. the variation of the flow rate of molten metal into the mould can be taken as a variation of the drawing speed of the cast product, so that when the drawing speed is monitored, it can be used as a parameter representing the flow rate of the molten metal into the mould. In use of the continuous casting installation, the following methods are utilized:
Method (i) A method for calculating the flow rate of molten metal from a ladle into a tundish using the drawing speed of a cast product as a basis
The flow rates of molten metal from a ladle into a tundish and thence into a mould, and the height of the molten metal within the tundish, are connected by the following equations:
Where Qj = flow rate of molten metal from a ladle into a tundish, Ql, = flow rate of molten metal from the tundish into a mould, Ht = height of molten metal within the tundish, A1 = cross-section area of the tundish.
A2 = cross-section area of the tundish spout a1 = flow rate coefficient
Calculating the relationship between the flow rates Qi and Q0 from Equations (1) and (2) above, the following equation is obtained: 5 10 15 20 25 30 35 40 45 50 55 60
Qi = Qo + KlQdOo . (3)
dt
where K1 = A1/gα12A22 The flow rate of molten metal from the tundish into the mould at any instant can be represented in terms of the drawing speed of the cast product, as follows:
dHm QO - A3U = A3 dt (4)
Assuming that the level of molten metal within the mould can be maintained constant by means of a mould level control device, then dHm/dt = O is satisfied, and thus we obtain: Q0 = A3U (5) where A3 = cross-section area of the mould
U = drawing speed of the cast product
Hm = height of molten metal within the mould
Substituting Equation (5) into Equation (3) the relationship between the flow rate of molten metal from the ladle into the tundish and the drawing speed of the cast product may be obtained as follows:
Qi = A3 (U + KlA3U dU (6)
By means of Equation (6). the flow rate of molten metal from the ladle into the tundish can be calculated from the drawing speed of the cast product.
In the case where Equation (6) is solved using a digital computer, the differential term dU/dt may be represented in terms of increments. That is the differential term can be calculated from a change in the drawing speed during a small interval of time using the following equations:
dU AU = Un - Un1 ~ Un - Un-i dt AT Mr - Tn- Ts (7) where Un = drawing speed at the present sampling instant Un~l = drawing speed at the last sampling instant
Ts = sampling time interval (Un - Uni) represents the change in the drawing speed during the sampling time interval. Substituting Equation (7) into Equation (6), the following relationship can be obtained:
Un - Un-1
Qin = A3(Un + KIA3Un ) (8)
Method (ii) A method for deriving the relationship between the flow rate of molten metal from the ladle into the tundish and the stroke of the ladle valve
The opening area of a ladle valve can be represented in terms of the valve stroke as follows:
S = AS.St, (9) where S = opening area of the ladle valve,
AS = change of opening area per unit length of stroke,
St = valve stroke.
According to Equation (9), the flow rate of molten metal from the ladle into the tundish can be represented as follows:
where a2 = flow rate coefficient,
H, = height of molten metal within the ladle.
Thus, the flow rate of molten metal from the ladle into the tundish becomes a function of the stroke, and assuming that there is no variation of the height of the molten metal within the mould during a very short interval of time, the relationship between the stroke and the flow rate of molten metal can be represented approximately by a linear equation, as follows:
St = f(Qi)
= K2Qj + K3 (11)
Method (iii) A method for detennining the optimum stroke corresponding to a preset value of the drawing speed of a cast product by utilizing the methods (i) and (ii) above
The flow rates of molten metal from a ladle into a tundish when T=Tm, St=Stm and
T=Tn, St=Stn can be represented, respectively, as follows: Um - Um-1) (12)
Qim = A3(Um + K1A3Um ) (12)
Ts where S, = Stem. and
Qin = A3(Un + KIA3Un Un - Un-1) (13)
Ts
where St = Stun.
If the coefficients K2 and K3 in Equation (11) are calculated by means of the data (Stm,
Qim) and (Stn, Qin), then the relationship between the stroke and the flow rate of molten metal from the ladle into the tundish is represented as follows:
The flow rate of molten metal corresponding to a preset value of the drawing speed of the cast product is represented as follows:
Qset = A3U, (15)
where Qset = a preset value of the flow rate of molten metal,
Us = a preset value of the drawing speed of the cast product.
Substituting Equation (15) into Equation (14), the optimum valve stroke can be represented as follows (See Figure 2):
As described above, the ladle valve is controlled through the following steps. The flow rate of molten metal for the existing opening of the ladle valve is calculated according to "method (i)". The relationship between the flow rate of molten metal and the ladle valve opening is derived using the data for the ladle valve opening and the flow rate of molten metal at two instants of time according to 'method (ii)". The optimum stroke for the preset value is determined according to "method (iii)". If the relationships between the flow rate of molten metal from the ladle into the tundish, the ladle valve opening, and the drawing speed of the cast product are always calculated and checked as described, then sufficient provision can be made for external influences such as wear of the ladle valve, defects of the spout lining, etc.
In view of the above described features and effects, the invention can provide the following practical advantages:
1. In contrast to the previous manual method of operation, it is no longer necessary to employ a ladle operator when using the present invention.
2. Since a load cell or the like does not have to be used as a detector and the drawing speed of a cast product is used instead, the apparatus becomes simpler.
3. Since the drawing speed of a cast product which is the final objective is employed as a control parameter instead of the known control methods which depend upon ladle or tundish weight, sensitive control is possible despite external influences such as variations in the dimensions of the tundish spout or the like.
4. A mathematical model whose control depends only on the drawing speed of the cast product, has been established.
5. Continuously cast products having a uniform quality can be manufactured.
6. Although a controlled valve may be subject to cyclic variation in conventional control systems employing PID regulators, because a tundish has a finite capacity and thus a definite integrating characteristic, in the method for determining an optimum stroke according to the present invention, a definite setting becomes possible and any cyclic variation can be substantially prevented by providing an appropriate insensitive zone for the controlled valve.
While the invention has been described in connection with specific apparatus, it is to be clearly understood that this description is by way of example only, the scope of the invention being defined in the following claims.
WHAT WE CLAIM IS:
1. A method for the control of the valve of a ladle of continuous casting apparatus during the continuous casting of a cast product, characterised by the steps of monitoring the drawing speed of the said product by detector means, subjecting the monitored drawing speed to an arithmetic processing by arithmetic means to calculate at any instant the required opening of the ladle valve in relation to the particular drawing speed at said instant. such that the pouring rate through said opening corresponds to the setting rate of the molten metal at said particular drawing speed, and maintaining the ladle valve continuously at an appropriate required opening in relation to the particular drawing speed
**WARNING** end of DESC field may overlap start of CLMS **.
Claims (4)
1. In contrast to the previous manual method of operation, it is no longer necessary to employ a ladle operator when using the present invention.
2. Since a load cell or the like does not have to be used as a detector and the drawing speed of a cast product is used instead, the apparatus becomes simpler.
3. Since the drawing speed of a cast product which is the final objective is employed as a control parameter instead of the known control methods which depend upon ladle or tundish weight, sensitive control is possible despite external influences such as variations in the dimensions of the tundish spout or the like.
4. Continuous casting apparatus of the kind having a ladle for molten metal connected to a tundish via a ladle valve, and a mould into which molten metal from the tundish is caused to flow at a controlled rate, characterised in that a speed detector is provided for detecting the speed of the cast product issuing from the mould, and arithmetic means are provided which are arranged to receive data from the speed detector for arithmetic processing, thereby to determine a required opening for the ladle valve, using a method according to any one of the preceding Claims.
4. A mathematical model whose control depends only on the drawing speed of the cast product, has been established.
5. Continuously cast products having a uniform quality can be manufactured.
6. Although a controlled valve may be subject to cyclic variation in conventional control systems employing PID regulators, because a tundish has a finite capacity and thus a definite integrating characteristic, in the method for determining an optimum stroke according to the present invention, a definite setting becomes possible and any cyclic variation can be substantially prevented by providing an appropriate insensitive zone for the controlled valve.
While the invention has been described in connection with specific apparatus, it is to be clearly understood that this description is by way of example only, the scope of the invention being defined in the following claims.
WHAT WE CLAIM IS:
1. A method for the control of the valve of a ladle of continuous casting apparatus during the continuous casting of a cast product, characterised by the steps of monitoring the drawing speed of the said product by detector means, subjecting the monitored drawing speed to an arithmetic processing by arithmetic means to calculate at any instant the required opening of the ladle valve in relation to the particular drawing speed at said instant. such that the pouring rate through said opening corresponds to the setting rate of the molten metal at said particular drawing speed, and maintaining the ladle valve continuously at an appropriate required opening in relation to the particular drawing speed
to control the flow rate of molten metal from the said ladle to a tundish, from which molten metal is caused to flow to the mould at a rate such that it continuously corresponds to the setting rate of the molten metal.
2. A method according to Claim 1, characterised in that the arithmetic processing includes calculating the flow rate of molten metal for the existing opening of the ladle valve, and deriving the relationship between the said flow rate and the ladle valve opening at two instants of time, the said required opening being determined therefrom.
3. A method for the control of a valve of a ladle of continuous casting apparatus substantially as hereinbefore described with reference to the accompanying drawing.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4410677A JPS53129125A (en) | 1977-04-19 | 1977-04-19 | Ladle value control apparatus in continuous casting |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| GB1602327A true GB1602327A (en) | 1981-11-11 |
Family
ID=12682349
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB1428378A Expired GB1602327A (en) | 1977-04-19 | 1978-04-12 | Method and apparatus for continuous casting |
Country Status (5)
| Country | Link |
|---|---|
| JP (1) | JPS53129125A (en) |
| BR (1) | BR7802384A (en) |
| DE (1) | DE2817115A1 (en) |
| FR (1) | FR2387715A1 (en) |
| GB (1) | GB1602327A (en) |
Families Citing this family (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5477229A (en) * | 1977-11-22 | 1979-06-20 | Ishikawajima Harima Heavy Ind | Method and apparatus for controlling drawing speed and mold level in continuous casting machine |
| DE2926863C2 (en) * | 1979-07-03 | 1983-10-27 | Zimmermann & Jansen GmbH, 5160 Düren | Method for controlling the pouring slide of a pouring vessel |
| EP0030991A1 (en) * | 1979-12-21 | 1981-07-01 | ATELIERS DE CONSTRUCTIONS ELECTRIQUES DE CHARLEROI (ACEC) Société Anonyme | Industrial process control-system |
| US4597048A (en) * | 1983-09-07 | 1986-06-24 | United States Steel Corporation | Digital flow regulation of liquid-level control for a continuous casting mold |
| JPS6096358A (en) * | 1983-10-28 | 1985-05-29 | Sumitomo Metal Ind Ltd | Operating method of continuous casting installation for light-gage billet |
| JPS60203350A (en) * | 1984-03-29 | 1985-10-14 | Sumitomo Metal Ind Ltd | Method for controlling molten metal level in continuous casting of thin billet |
| DE3869609D1 (en) * | 1988-08-31 | 1992-04-30 | Metacon Ag | FIRE-RESISTANT PLATE SET FOR THREE-PLATE SLIDING LATCHES. |
| ATE74544T1 (en) * | 1988-08-31 | 1992-04-15 | Metacon Ag | METHOD FOR CONTROLLING VALVE LOCKS, ESPECIALLY ON CONTINUOUS CASTING PLANTS. |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR1493344A (en) * | 1966-09-21 | 1967-08-25 | United States Steel Corp | Mixed control system for controlling the level of molten metal in a continuous casting mold |
| US3521696A (en) * | 1967-04-19 | 1970-07-28 | Brun Sensor Systems Inc | Continuous casting line speed control |
| US3605862A (en) * | 1969-05-08 | 1971-09-20 | United States Steel Corp | System for feedback control of mold level in a continuous casting process utilizing a pour box |
| DE2232320A1 (en) * | 1972-06-27 | 1974-01-31 | Mannesmann Ag | Continuous casting mould metal level - is controlled by computer controlled stopper setting |
-
1977
- 1977-04-19 JP JP4410677A patent/JPS53129125A/en active Pending
-
1978
- 1978-04-12 GB GB1428378A patent/GB1602327A/en not_active Expired
- 1978-04-18 BR BR7802384A patent/BR7802384A/en unknown
- 1978-04-19 DE DE19782817115 patent/DE2817115A1/en active Pending
- 1978-04-19 FR FR7811469A patent/FR2387715A1/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| DE2817115A1 (en) | 1978-10-26 |
| FR2387715B1 (en) | 1982-05-28 |
| BR7802384A (en) | 1978-12-12 |
| FR2387715A1 (en) | 1978-11-17 |
| JPS53129125A (en) | 1978-11-10 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PS | Patent sealed | ||
| PCNP | Patent ceased through non-payment of renewal fee |