JPS58125352A - Control of molten metal level in continuous casting - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to level control of molten metal in a vertical continuous or semi-continuous casting apparatus, and more particularly to the control of the level of molten metal produced by an annular guiding device surrounding the sides of the molten metal.

The present invention relates to a casting device in which the generated electromagnetic field is used to form solidified metal.

Aluminum ingots or billets that are continuously or semi-continuously directly cool cast in conventional open-type tubular molds suffer from cooling browning scratches (coil fo14) and elution (coil flaws) caused by contact between the mold and the outer surface of the unfinished solidified metal. 1qua
tion), hot tears, etc. Initial cooling and local solidification of the molten metal surface by contact with the cooling surface of the hole of a traditional direct-cooled cast indent or billet mold, reheating of the metal after it has shrunk and withdrawn from the mold hole, and cooling fluid. It is characterized by pronounced surface alloying separation due to the continuous process of final solidification of molten metal by direct feeding of molten metal. Conventional direct-cast in-vites or billets are typically milled to remove both surface defects and poor alloy layers near the surface prior to processes such as rolling or rolling.

N processes are required.

The electromagnetic casting method uses an annular induction device instead of the tubular mold used in conventional methods, and the direct supply of cooling fluid allows control of the shape of the metal until it reaches its final shape. It is very similar to conventional direct cold casting methods, except that it generates an electromagnetic field around the sides of the molten metal that exerts radial pressure on the molten metal column. In operation of electromagnetic casting equipment, there is no contact with the outer surface of the molten metal during solidification, and therefore the aforementioned surface defects are rarely seen. Additionally, because there is no contact between the outer surface of the molten metal and the cooling surface of the mold hole, there is little indentation or alloy deterioration near the surface of the billet, so the electromagnetically cast metal is highly uniform across its entire cross section. becomes.

There is no need to cut electromagnetically cast metal prior to other processes, and as an added benefit, this uniform configuration eliminates to a large extent the edge cracking of traditional direct cold casting indentations during hot rolling. It is something to do.

The electromagnetic field in the electromagnetic casting method is formed by an annular induction device, and the cross-sectional shape of the solidified metal is determined by the interaction between the electromagnetic field generated by the induction device and the vortex induced in the molten metal within the inner periphery of the electromagnetic casting method. Electromagnetic power that dominates occurs. The radial force controls the horizontal position of the molten metal so that nothing comes into contact with the solidifying metal until the coolant is supplied to the metal surface from the bottom of the induction device. The metal solidifies primarily due to the axial conduction of heat from the molten metal towards the solidified metal supplied with the cooling fluid.

The induction device is preferably powered by a high frequency power source (e.g. 500-15000 cycles/sec)? This is what we have in place.

More detailed information on the principles of the electromagnetic casting method can be found in U.S. Pat.
No. 3,467,166, U.S. Pat. No. 3,605.
No. 865, No. 3.646.988, No. 3,702
．． No. 155, No. 3,773,101, No. 3,98
No. 5,179 and No. 4,004,651.

In an electromagnetically cast ink piece or billet having a constant cross-sectional shape in the axial direction, the radial component of the electromagnetic pressure is dynamically continuously balanced with the hydrostatic pressure of the molten metal. The control required for mechanical equilibrium is much more difficult than it appears at first glance, since subtle changes in the electromagnetic field, rate of descent, or height of the molten metal can significantly change the final indentation and cross-sectional shape of the billet. It's difficult. When the local pressure of the molten metal becomes greater than the radial electromagnetic pressure and solidifies, a rapid flow of the molten metal over the bottom deck similar to the "icicle phenomenon" at the root end of an inuit or billet is triggered. care must be taken, especially at the starting point. It is difficult to cast a single indent or billet so that its cross-sectional shape is uniform throughout its length, and it is even more difficult to cast a plurality of indents or billets using the same casting device.

Although many methods for controlling the shape described above have been proposed, they have not yet been widely put into practical use. No. 4,014,379, the current level of an induction device is controlled in response to detected deviations based on the height of molten metal within the device. Similarly, although U.S. Pat. has been done. In either of these cases, the current level in the induction device is changed to adjust the electromagnetic pressure to account for the difference between the measured distance and the desired distance.

Although the prior art methods described above provide some control over the size of the input goatlets, the control over the shape is far from what is desired. Furthermore, these methods themselves cannot be easily applied to control electromagnetic casting of a plurality of ingots or billets in one casting apparatus. The present invention eliminates these drawbacks.

The present invention relates to a method for controlling the level of molten metal in vertical continuous or semi-continuous casting equipment, such as direct cooling and electromagnetic casting equipment. More particularly, the present invention relates to a method and system for accurately detecting and controlling the level of molten metal.

According to the invention, the level of molten metal is detected by a displacement transducer that generates a signal proportional to the detected metal level. The signal representative of the detected molten metal level is compared to a set signal representative of the desired molten metal level to generate an error signal representative of the difference between the detected molten metal level and the desired molten metal level. Operation of the device for controlling the flow of molten metal into the molten metal body is controlled in response to the error signal with the operating distance of the control device being proportional to the error signal. In this manner, molten metal level control is accurately achieved over the desired operating range.

In a preferred embodiment, molten metal is injected into the molten metal body through a tube having a valve arrangement. The valve device is rotated by an actuator that operates in response to an error signal.
It is actuated indirectly or directly via a linkage by an Archimedean line-shaped cam. The rotation of the cam is proportional to the error signal, and the distance from the rotation axis of the cam's working end of the "Archimedes' bright line" is directly proportional to the cam's rotation, so the cam's working end is The movement of is also proportional to the error signal. In this way, the molten metal tube flow pupil control device is controlled proportionally to the error signal, and therefore the molten metal flow rate is also proportionally controlled.

Accurately controlling the level of molten metal in many casting machines, particularly when the flow rate of molten metal in each of the electromagnetic casting machines is controlled to maintain the molten metal level in each casting machine approximately constant throughout the casting process. is very important. In order to simplify this control, each casting device is precisely fixed on a support such as a table so that the guiding device and the mold are installed at the same level. One or more supports for the bottom pegs are provided so that all of the injects and billets descend at the same speed.

Level control in a plurality of casting machines according to the invention includes:
Detects the molten metal level of each casting device and linearly represents each detected level of molten metal. This is done by comparing each detected signal to a set signal from a master controller that is generated and represents the desired molten metal level in all casting equipment. The overall molten metal for a particular casting device is automatically controlled by device K, which operates linearly with respect to the difference between both signals and brings the molten metal level in the particular casting device to the desired level. At a controlled time from the start of operation, the molten metal level in each casting device should be 0.10 inches (0.25), preferably 0.05 inches (0.25).
, 15m) will not change beyond 1r. Furthermore, after the initial start-up, the overall level of molten metal in the induction device for the same casting equipment changes by 0.10 inches (0.25e
M) t - preferably not exceeded. Beyond these ranges, the cross-sectional shape of each ingot or billet varies significantly along its length, and the cross-sectional shape of ingots or billets within the same casting apparatus also varies significantly from location to location. There is no substantial cooling solidification of the molten metal as it passes through any casting equipment, and there is no substantial rapid flow of molten metal across the end of the bottom block located within the induction equipment at the start of casting. There is a major problem with electromagnetic casting machines because the molten metal in all electromagnetic casting machines must reach the same predetermined level before the bottom block drops in the state. Casting equipment furthest from the molten metal source tends to solidify the metal first, and the molten metal flow rate of the casting equipment furthest from the molten metal is therefore greater than that closer to the source. Preferably all casting equipment is draw fed.

That is, the downstream flow to the casting equipment is less than the maximum molten metal flow at any time during casting in the controlled process.

The molten metal level is automatically maintained during casting to be within the range mentioned above. In the final stage of casting, the molten metal source is opened and the molten metal in the passageway is injected into the casting apparatus until a certain level of molten metal cannot be maintained in any casting apparatus. At this time, the channel is raised and completely poured into the container and removed from the casting area, the table is raised or moved, and the ingot or billet is removed from the casting pit. When the passageway is raised for draining, the casting equipment closer to the drain container will receive more molten metal than the one further away, and all inits and billets will be essentially the same length, leaving the drain container with more molten metal. The level of molten metal in nearby casting equipment is reduced before casting is complete. The height variation of the molten metal level is small, 1 inch (2,543), preferably 0.1 for large sheet ingots.
~0.5 inch (0.24-1.27 cIR).

At the end of the casting process, the supply of cooling liquid to the surface of the ingot or billet at the exit end of the induction device or mold is continued until solidification is achieved, and the end of the ingot or billet is discharged from the induction device or mold. Ru.

The control method described above is suitable for many casting machines.

In the operation of electromagnetic casting equipment, the height of the level of molten metal within the induction device has a linear relationship to the electromagnetic pressure generated by the electromagnetic field. In a preferred embodiment, the electromagnetic field and resulting pressure is kept constant while being controlled to vary the lateral level of molten metal within the induction device. This control method requires that the induced currents have the same amplitude and frequency in each casting device. Odor modification of this control method is also possible.

The present invention will be described in detail below with reference to the accompanying drawings. Referring to FIGS. 1 to 5, the electromagnetic casting apparatus generally includes a cooling jacket induction device 10, a bottom block device 11, and a molten metal supply device 12t.

The cooling jacket induction device 10 has an electromagnetic inductor 14 as its innermost wall, and the cough electromagnetic inductor has an earth wall member 15,
It is fixed together with the bottom member 16 and the rear wall member 1T in a sealed structure. A cooling jacket (the interior of the induction device is divided into two annular cooling chambers 19 and 20) is provided by a partition wall 18 provided concentrically near the rear wall of the electromagnetic induction body 14. The partition wall 18 has a conduit 21. The cooling liquid flows out from the cooling chamber 19 to the cooling chamber 20.The cooling liquid from the cooling chamber 20 is formed in the lower part of the electromagnetic induction device 14, passes through the Kakegawa pipe 22, and enters the condensate in♂ The cooling jacket wall members 15, 16, 17, 18 towards the jet or billet 23 are preferably manufactured from a non-metallic material such as a suitable plastic.

The upper portion 25 of the electromagnetic inductor 14 is preferably inclined relative to the vertical axis of the cooling jacket induction device 10 as shown and rests on the upper portion of the molten metal sidewall 26 according to U.S. Pat. No. 3,985.179. Accurate pressure control is achieved by reducing electromagnetic force. Upper part 2 relative to the vertical axis of the device 10
The 50 angle is determined by factors such as molten metal level, input and billet size. Usually, desired,
The angle of is determined empirically to be in the range of approximately 10-50 degrees.

The electromagnetic inductor 14 is a metal such as steel or aluminum,
In order to protect against accidental contact with molten metal, the surface is preferably coated with a non-metallic coating (not shown) that does not significantly affect the electromagnetic field generated by the electromagnetic inductor 14.

The cooling jacket guiding device 10 is attached to the casting table 27 by means not shown. Casting table 27
is mounted on a four-wheeler) or -10,000, and is hinged to allow the bottom block 30 and the attached guiding device 10 to be moved at the end of the casting process, so that the screws cast from the casting bit are Input and billet 23 can be taken out.

The bottom block device 11 is also clearly shown in FIG.

As shown, the bottom block 30 is supported and mounted on the same table or support 31 via a stand 32 so as not to change the rate of descent between casting machines. Since even a sudden and slight movement greatly affects the size and shape of the inuit or billet, the lowering of the support 31 must be done smoothly and uniformly. bottom block 3
Although it is more convenient to support and lower all the bottom glocks 30 on the same support 31 in the same manner as before, each bottom glock 30 may be lowered independently if desired.

The molten metal feeder 12 includes a feed passage 35 preferably made of a non-magnetic material such as stainless steel, and the feed passage 35 is provided with a refractory lining 36. The molten metal 37 is distributed to the plurality of electromagnetic casting apparatuses 10 by sprues 38 that protrude into the inner circumferential region of the electromagnetic inductor 14 .

The flow of molten metal into the electromagnetic inductor 14 is controlled by a flow control valve, shown as a needle or plug valve arrangement 40.

The end 41 of the valve body is connected to the recess 4 formed in the upper part of the sprue 38.
It is configured to be in contact with the valve seat indicated by 2.

As shown in more detail in FIGS. 4 and 5, the upper part 43 of the valve body 40 is preferably formed with a bright line groove, and the valve body 40
It has a corresponding threaded collar 44 for fine adjustment of the position of the valve 0 relative to the valve seat 42.

The collar 44 has an arm 45 formed in the yoke portion 47 of the lever arm 48 and located in the recess 46 . Lever arm 48 is pivotally mounted at points 49 and 50, and rotation of lever arm 48 about points 49 and 50 raises and lowers valve body 40 to control the flow of molten metal into inductor 14. A balance weight 51 is attached to the end of the arm 48.
is provided.

The arm 48 is moved by rotation of a cam 55 driven by a rotation actuator 56 such as a motor in response to a predetermined control signal. The cam 55 preferably has an "Archimedean screw" shape as shown, whereby a fixed percentage of the rotation of the cam 550 causes the lever arm 48 in contact with the actuation profile of the cam 55 to move linearly at a fixed percentage. Therefore, the valve body 40 also moves in the same manner. The amount of rotation of cam 550 by rotation actuator 56 is directly proportional to an error signal representing the deviation of the actual molten metal level from the desired molten metal level. The amount of rotation of cam 550 and the amount of elevation of flow control valve 40 are directly proportional to the difference between the actual and desired molten metal level. In this way very precise molten metal level control is maintained throughout the casting process.

Before casting begins and a predetermined valve opening is reached, the valve body 40 is preferably remotely reset via the rotary actuator 56. The valve opening and molten metal flow rate of casting equipment further away from the molten metal supply source are greater than those of casting equipment closer to the molten metal supply source. This adjustment allows correction of the initial flow rate for casting in casting equipment near the molten metal source and helps prevent solidification prior to casting.

Molten metal level detection in each casting device is carried out by a float 60 floating on the surface 61 of the molten metal 26 within the electromagnetic inductor 14.
This is achieved by Float 60 is lot)? 62 and a connector member 63 to the shaft 64 of the linear displacement transducer 65.
generates a linear output signal representative of the molten metal level detected by the molten metal level.

A guide member 66, such as a bracket, is secured to the side of the passageway 35 to guide the vertical displacement of the rod 62 during the casting process. A collet 67 is attached to the rod 62 to prevent the float 60 from moving downward during non-casting.

The displacement transducer 65 is approximately 4 inches (approximately 10 m) long (7")'
t O,01(:/f (0,025
crn), preferably 0.005 inches (0,016
crn). A preferred transducer is the Model 2000 HPA from Shavits Carp, New York, NY. In order to maintain the linearity of the output with respect to the detection level, certain conditions are required for the signal from the converter at the upper and lower limits of the range. Although the level detection and signal generation device has been described here primarily as a float coupled to a linear displacement transducer, it is understood that other devices can also be used for level detection, as long as a linear signal representative of the detected level is generated. it is obvious.

The "linear" or "proportional" suspension chains used here are
In the operating range of interest, the relationship does not deviate from the true linear relationship by more than 5%, preferably by 1% or more - a relationship regarding two variables.

The vertical position of float 60 is critical to accurately controlling the molten metal within electromagnetic inductor 14.

The material for the float is one that does not adsorb molten metal or impurities, and the float 60 is
To prevent variations in the float 60, it must remain intact throughout the casting process. As a float material, John Mantle Company (John
Marinite (Manville Carp), a lightweight fiber refractory material manufactured by Manville Carp
Rl ni to, registered trademark) is preferred displacement transducer 65
is fixed to passageway 35, and because it is necessary to accurately mount the transducer when the passageway is mounted and positioned to accurately measure the molten metal level in dielectric 14, passageway 35 is shown in FIG. As shown, it is accurately mounted and positioned on the casting table 2T.

Attachment of the passageway 35 is accomplished by engaging one or more male cones 68 of the ends of the passageway 35 located precisely in the female 1170. The opposite end of the passageway 35 is attached exactly to the outlet or passageway of a filter degassing device, not shown.

As shown schematically in FIG. 6, the molten metal level control system that controls all of the casting equipment includes a master controller that provides control signals and molten metal level setting commands to local controllers 71 associated with each casting equipment. 80. Each local controller 71 compares the signal representing the sensed condition or molten metal level with the signal from the master controller 80 representing the desired set point and commands the necessary corrective action. Only one casting apparatus is shown for simplicity. Master controller 80 also directs other operations via controller 82 to lower the bottom block and control the flow of coolant.

A suitable controller unit as the master controller 80 is manufactured by Goull Com-pa.
A suitable local controller 71 is a model & 484 model controller sold by the Model & Northrup Department, Andover, Minnesota.
Elsctromax [1], sold by Northrup Co., North Wales, NC.

During the casting process, molten metal level 61 is sensed by float 60 and displacement transducer 65 generates a signal representative of the sensed molten metal level. The detected molten metal level is sent to local controller 71 which compares the detected signal with a signal from master controller 80 representing the desired molten metal level. If there is a difference between the two signals, the local controller T1 sends a control signal to the rotary actuator 56, causing the cam 55' to rotate, raising and lowering the valve body 40, and appropriately controlling the flow rate of molten metal to the casting device. , so that the upper surface 61 of the molten metal is maintained at a predetermined level.

A suitable rotary actuator is the one made by Foxboro/Jorda.
Model A 8M-1180 manufactured and sold by nInc, ), Milwaukee, Rice Consin.
It is an actuator. Model AD 7550 5
A standard Foxboro/Zoyoda amplifier is usually included to drive the actuator. The output of the rotary actuator, and thus the cam 55, is directly proportional to the signal controlling actuation of the actuator.

The master controller 80 is each 11es model
- The same predetermined molten metal level setting signal is sent to the casting controller 71, so that the molten metal level of each casting device becomes approximately the same horizontal plane. For this reason, the electromagnetic casting apparatus, each containing a dielectric, a level float, and a displacement transducer, must be precisely positioned at the same relative level.

Is the casting black during casting? To prevent the occurrence of thermal distortions, it is preferable to water-cool the passageway 35 and the induction device.

The systems and methods of the present invention allow for very precise control of input and billet size and shape. For example, 19X43X138 (inch) (48,3
When five inits of the shape (x109.2x350.5crt+) are electromagnetically cast, the maximum deviation of the maximum cross-sectional size along the length of the input (excluding vertical base expansion) is 0. It was less than 1 inch (0.25ffi). The maximum deviation between inputs was less than 0.25 inches (0.64 m).

Although the present invention has been described in detail above, it goes without saying that many modifications can be made within the scope of the present invention.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway perspective view of an electromagnetic casting apparatus according to the present invention;
Fig. 2 is a plan view showing a plurality of casting devices in one casting station, Fig. 6 is a partially cutaway side view of two casting devices taken along the line ■-■ in Fig. 2, and Figs. The figures show side and top views of a valve actuated arm loading controlling the flow of molten metal from a passageway to a mold or electromagnetic inductor;
The figure is a schematic diagram of a molten metal level control system. DESCRIPTION OF SYMBOLS 10... Cooling jacket induction device, 11... Bottom Glock device, 12... Molten metal supply device, 14... Electromagnetic induction material, 19.20... Cooling chamber, 23... Inlet or billet , 27...casting table, 3o
... resistance block, 35 ... supply passage, 38 ... sprue, 40 ... valve body, 42 ... valve seat, 55 ... cam, 56 ... actuator. Attorney: Akira Asamura Procedural Amendments Sent February/6, 1982 Dear Commissioner of the Japan Patent Office 1. Indication of the case Patent Application No. 205554 of 1988 2. Name of the invention Method for controlling the level of molten metal in continuous casting 3 , Relationship with the person making the amendment 1. Patent applicant 4. Agent 5. Date of supplementary E.E. order. )

Claims (1)

[Claims] (1) A direct cooling or electromagnetic casting process having an open tubular casting apparatus having a free end and a discharge end, wherein the molten metal is passed from its source through a tube having a flow control valve to the casting apparatus. A casting method in which solidified or partially solidified metal is discharged from the discharge end of the casting apparatus and a coolant is supplied to the casting apparatus, comprising: (a) detecting a level of molten metal and generating a signal proportional to the level of molten metal detected; (b) comparing said signal representative of the detected level of molten metal with a signal representative of a desired level of molten metal; and (C) controlling the flow control valve t by a controller operative in response to the signal representative of the difference and having a working distance proportional to the signal representative of the difference. -h A method for controlling a molten metal level, characterized by performing closed control. (2. In the control method according to claim 1, the control device that operates in response to the signal representing the difference causes an Archimedean screw to be rotated by an actuator that operates in response to the signal representing the difference. It has a linear cam,
A method for controlling a molten metal level, characterized in that the rotation of the cam is proportional to the signal representing the difference and the operation of the control device is controlled indirectly or directly by the cam.