lo~3~3 This invèntion relates to a continuous casting process for casting solid billets. More particularly, this invention relates to a device for vertically, laterally and radially aligning a solid pouring mold mounted on an oscillating table o~
a continuous casting machineO
In all types of continuous casting processes, molten metal is converted to a solid billet in a bottomless solid copper mold tube, The mold tube is positioned below a metered stream of molten metal and is contained in a cooling jacket through which a high volume of cooling water is passed. The cooling jacket and mold are adjustably mounted on an oscillating mold table. The billet continuously withdrawn from the bottom of the mold tube has a solidified shell with molten metal still contained therein.
Some continuous casting processes are vertical systems in whic~
the billet passes vertically downwards and is cooled continuously by water sprays. Then, when it has solidified the billet is cut into predetermined lengths, Another type of continuous casting process is the curved mold type wherein the ~opper mold tube has a curve therein and the billet passing from the mold tube follows the curve and is guided by a series of rollers through an angle of 90 to a straightener withdrawal unit which straightens the continuous billet and cuts it into predetermined lengths, A continuous pour generally lasts for one to one and a ;~ half hours during which time approximately 25 tons per mold of metal may be formed into predetermined billet lengths, After a certain number of pours, wear occurs in the mold tube, and it is necessary to replace it. This replacement step requires the new mold tube to be accurately aligned with the rest of the machine.
Any misalignment that exists between the mold tube and the casting machine can cause undue stresses to occur on the thin shell of the billet around the molten metal contained therein as the billet leaves the bottom of the mold tube, Undue stresses have a number of consequences ranging from a distorted billet with internal faults to a rupture or break-out of the molten metal from the shell. Break-outs cause metal to spill into the machine which terminates the process and results in considerable clean-up before the casting process can be restarted.
The mold tube and cooling jacket are generally formed tog0ther as one unit which can be removed from the mold adaptor plate on the machine and replaced by another unit so that the casting machine can continue operating while the old mold tube unit is returned to a maintenance shop for repair. In this manner mold tube units can be repaired and maintained at leisure and without holding up the process of casting. Furthermore, the size of mold tube can vary to allow various size ranges of billets to be cast. For different sized billets, different sized mold tubes must be installed. In practice it is found that mold tubes are never positioned in exactly th0 same place in the mold tube units. Thus, every time a new mold tube unit is placed into a continuous casting machine it is necessary to realign the adaptor plate mounted on the oscillating table. In the past the alignment has often caused some problems because the mold tube was positioned by aligning up the outside of the cooling jacket with the casting machine. However, the inside of the mold tube is frequently out of alignment with the outside of the cooling jacket and thus true alignment of the mold tube with the machine was often not achieved. Consequently, casts sometimes produced distorted billets which are not the correct weight and this in turn causes considerable problems in the rolling of the bi]lets into rolled sectionsO
It is an object of the present invention to provide an alignment device to align up the internal surfaces of a mold tube with a continuous casting machine.
It is a further object of the present invention to provide an alignment tool to align a mold tube in a continuous casting machine, the device being one which is easy to install into the mold tube.
It is still a further object of the present invention to provide a simple method of aligning a mold tube vertically, laterally and radially, in a continuous casting machine, These and other objects of the present invention are acc~mplished by providing a device for aligning up a pouring mold tube in a continuous casting machine wherein the mold tube has at leas$ one pair of vertical parallel internal walls and is surrounded by a mold cooling jacket both connected to an adaptor plate which is~adjustably mounted on an oscillating table, the device comprising: a mold insert portion having a pair of parallel faces adapted to mate with one pair of vertical parallel internal walls in the mold tube, a vertical alignment means attached to the top of the mold insert portion adapted to indi-cate when the mold insert portion and hence the mold tube is in a vertical position and a radial and lateral alignment means attached to the mold insert portion adapted to indicate when the mold insert portion and hence the mold tube is radially and laterally aligned.
The present invention also provides a method of aligning a pouring mold tube in a continuous casting machine wherein the mold tube has at least one pair of vertical parallel internal walls and is surrounded by a mold cooling jacket both connected to an adaptor plate, which is adjustably mounted on an oscillating table, the improvement comprising the steps of:
inserting a mold insert portion of an alignment device between and pressing against the vertical parallel internal walls of the mold tube, adjusting the elevation of the adaptor plate relative to the oscillating table such that a plumb line on the alignment - 3 _ i3V
device shows the mold tube is vertically aligned, ad~usting the radial and lateral alignment of the adaptor plate relative to the casting machine such that a horizontal elongate element aligned with the casting machine is aligned with two marks one at each end of an elongate member of the aligning device and securing the adaptor plate in its aligned position firmly to the oscillating table.
The advantage of this invention both as to its construc-tion and mode of operation will be readily appreciated as the same becomes better understood by reference to the following det-ailed description when considered in connection with the accom-panying drawings which illustrate an embodiment of the invention.
Figure 1 shows a schematic side elevation of a curved mold continuous casting machine of the type known in the prior art, with a partial cross-section through the mold tube.
Figure 2 shows a perspective view of an alignment device suitable for aligning a mold tube in a continuous casting machine O
Figure 3 shows a cross-sectional side elevation through 20 the centre of a mold tube of a casting machine similar to that shown in Figure 1, with the alignment device of Figure 2 posi-; tioned in the mold tubeO
Figure 4 shows a cross-sectional end elevation through the centre of a mold tube and alignment device shown in Figure 3.
Figure 5 shows a plan view of the mold cooling ~acket, adaptor plate and oscillating table with the alignment device positioned therein taken at line 5-5 of Figure 3.
Figure 6 shows a cross-section through the mold tube having the alignment device positioned therein taken at line 6-6 of Figure 4.
Referring now to the drawings, a continuous casting 1(~43~
machine of the curved mold type is shown in Figure 1, with a continuous steel billet 10 issuing from a curved mold tube 11 located in a mold cooling jacket 12. The mold tube 11 is pre-ferably made from copper to transfer the heat from the molten metal within the mold tube 11 to water which passes through the cooling jacket 12. The cooling jacket is attached to an adaptor plate 13 which in turn is adjustably mounted on an oscillating table 14. In the embodiment shown in Figure 1 the radius of the machine is 22 feet; thus, the billet 10 and the mold 11 have a 22-foot radius throughout their length. The oscillating table 14 oscillates about this curved radius to assist the billet 10 ~ leaving the mold 11 and ensure the billet 10 does not deviate ; from the path of the curved radius. The billet 10 leaving the mold 11 passes through a first spray zone, where water sprays 15 cool the billet, over a first roller 16 to a second spray zone, where water sprays 17 cool the billet further, over a second roller 18 to a third spray zone, where water sprays 19 cool the billet still further. The billet 10 then passes over three ~` further rolls 20 so that it follows its normal curve, and finally passes through three pairs of horizontal straightening rolls 21 in tandem to remove the curve from the billet 10. After this the straightened billet is cut to the required lengths, cooled and stored. Subsequently, billet lengths can be reheated for further processing into rolled sections.
In operation molten steel is poured from a ladle into a refractory-lined vessel referred to as a tundish which has a nozzle with a flow control valve positioned directly over the centre of the mold tube 11. When starting up the operation a dummy bar is plugged into the base of the mold tube 11 and a metered stream of molten steel pours through the tundish nozzle into the mold tube 11. Water is passed through the mold cooling jacket 12, preferably at a high volume rate in the order of 400 3(~
to 500 gallons per minute, The oscillation table 14 oscillates in a stroke which conforms to the radius of the casting machine and the dummy bar is slowly withdrawn through first, second and third spray zones to the three pairs of horizontal straightening rolls 21 in tandem. As the dummy bar is withdrawn, the steel billet forms behind it and once the billet has reached the three pairs of straightening rolls 21 the speed of withdrawal is then controlled by the rolls 21. The metered stream of molten steel falls about 14 inches into the top of the mold tube 11. When the billet 10 is withdrawn from the bottom of mold tube 11 it has a solidified steel shell from 1/2" to 3/8" thick which con- -tains the molten metal therein. This molten metal solidifes as the billet 10 cools by passing through the three spray zones.
Different sizes of billets may be poured by merely changing the size of mold tube 11 and varying the metered flow of molten steel into the mold tube 11 from the tundish. For example, billet sizes range from 4" x 4" square through 5 1/4" x 5 1/4" and 6 3/4" x 6 3/4" to 7 5/8" x 7 5/8". A continuous pour generally lasts for one to one and a half hours depending on the size of the billet and the amount of steel in the tundish.
After every hundred casts it is generally necessary to change the mold as a certain amount of wear occurs with the steel billet solidifying within the mold and then being withdrawn as the reci-procating table continually moves the mold tube 11 up and down.
One embodiment of the alignment device is shown in Figure 2~ The device is in the general configuration of a cross, the lower vertical portion being the mold insert portion 24 which is the portion for inserting inside the mold tube 11. The alignment device shown fitting inside a mold tube may be seen in Figures 3, 4, 5 and 6. The mold insert portion 24 has a generally rectangular cross-section and extends downwards so that it is at least as long as the depth of the mold tube 11. An elongate member 25 forms the horlzontal arms of the cross configuratlon and is securely mounted above the mold lnsert portion 24, Thus, when the device is lnserted into the mold tube 11 the elongate member 25 rests on the top edge of the mold tube 11 to assure that the alignment device is aligned relative to the mold tube 11. The elongate member 25 is rectangular in shape as shown in Figure 2. However, in the preferred embodiment both arms of the elongate member 25 taper slightly towards their outside ends as is shown more clearly in Figure 5. At each end of the arms of the elongate member 25 is a mark 26 in the centre. As also shown in Figure 2 a mounted strip 27 with a V-notch 28 therein is located at the outside end of one arm of the elongate member 25. The V-notch 18 is positioned in line with the two marks 26.
The top vertical arm of the cross configuration is formed into a slender arch 29 extending upwards from the centre of the elon-gate member 25 having a flexible elongate element 30 such as string or wire suspended from the top centre of the arch 29 and a plumb bob 31 attached to the end of the elongate element 30.
A cross 32 is marked on the top surface of the elongate element 25 directly beneath the plumb bob 31 such that when the plumb bob is hanging vertically, the tip of the plumb bob 31 points to the very centre of the cross 32.
The mold insert portion 24 has two parallel faces 33 which fit between the vertical faces 34 of the mold tube 11 as shown in Figure 6. In order to insure that these parallel faces 33 of the mold insert portion 24 press against the vertlcal walls 34 of the mold tube 11 a separate member 35 is spaced from the main portion of the mold insert portion 24. This separate member 35 is held to the mold insert portion 24 by means of dowels 36 as shown in Figure 6 and has two round rubber rods 37 extending vertically for the length of the separate member 35. These round rubber rods 37 compress when the mold insert portion 24 is 1~ 3~
pushed into the top of a mold tube 11 to in~ure there i9 always pressure against the vertical sides 34 of the mold tube 11. It will be appreciated that although only the one embodiment showing two rubber rods is illustrated, other compressible rubber inserts or even a single insert may be used. Also, steel springs may perform the same function. The separate member 35 is removable from the mold insert portion 24. Thus, several sizes of separate members 35 may be made available for fitting to the same mold insert portion 24 of the alignment device, to take into account different internal dimensions of the mold tube 11. For example, a 4" x 4" internal dimension mold tube would have a slim separate member 35 whereas a 6 3/4" x 6 3/4" internal dimension mold tube would have a considerably thicker separate member 35.
The alignment device is generally made from woodO
However, in order to avoid wear it is common to fit brass inserts 38 on each corner of the mold insert portion 24 so that when the mold insert portion 24 is inserted into the mold tube 11 the wood of the mold insert portion does not wear, and the alignment of the device within the mold tube remains true. In a preferred embodiment the elongate member 25 is made from wood and has a half round section of aluminum around it to protect the wood.
The mold cooling jacket 12 surrounding the mold tube 11 has water inlets 40 and water outlets 41, as shown in Figure 3.
Flexible hoses (not shown) are attached to the inlets and outlets so that the water supply to the cooling jacket 12 may be supplied while the mold tube is being reciprocated on the oscillating table 14. Cooling water in the order of 400 to 500 gallons per minute is passed through the cooli~g jacket 12 while the casting process is underway. The mold tube 11 is generally a press-fit within an inner sleeve of the mold cooling jacket 12 and may be removed in a maintenance area and a new one replaced as required.
Eight horizontal set screws 50-57, as shown in Figure 5 provide f3~30 horizontal adjustment of the adaptor plate 13 onto the 09cil-lating table 14, Four jacking screws 58-61 provide the vertical adjustment for the adaptor plate 13 and four hold-down bolts 62-65 are tightened down after the adaptor plate 13 has been aligned both vertically and radially in the casting machine.
In the process of aligning a new adaptor plate 13, mold cooling jacket 12 and mold tube 11 unit onto an oscillating table 14, it is first necessary to back off all the horizontal set screws 50-57, release the hold-down bolts 62-65 and then insert the alignment device into the mold tube 11. Insure that the parallel faces 33 of the mold insert portion 24 are pressed up against the vertical walls 34 of the mold tube 11. It is also necessary to insure that the mold insert portion 24 is pushed down into the mold tube 11 so that the elongate member 25 rests on the top edge of the mold tube 11 and is aligned vertically with the mold tube 11. The next step is to adjust the four jacking screws 58-61 so that the tip of the plumb bob 31 is exactly over the centre of the cross 32 on the elongate member 25, This assures that the mold tube 11 is vertically aligned in the casting machine. The next step is to align the mold tube 11 up radially and laterally with the casting machine and this is done by stringing a horizontal elongate element such as a wire 66 horizontally from two permanent positions on each side of the mold tube 11; the wire is so positioned to pass through the arch 29 of the alignment device and is tightened to give a straight data line on which to check alignment, The horizontal set screws 50-57 are then adjusted to rotate and laterally move the mold tube 11 as necessary so that the horizontal wire 66 lies in the centre of the V-notch 28 of the mounted strip 27 and the wire 66 is exactly in line with the two marks 26 on the elon-gate member 25. When these marks are in alignment with the wire 66 then the mold tube 11 is aligned radially and laterally and _ g _ 3~j~V
the alignment device has per~ormed its duty. Before tightening down the hold-down bolts 62-65 another alignment is required to insure that the curve of the mold tube 11 is in line with the curve of the casting machine. This alignment is done by another device which does not form part of the present invention. After the curve alignment the hold-down bolts 62-65 are tightened and the mold tube 11 is aligned ready to commence the pouring step.
Further changes may be made to the alignment device without departing from the scope of the present invention. In one particular case, the rubber rods 37 may be replaced by a threaded expansion means. This incorporates a threaded bolt extending vertically downwards through the mold insert portion 24 and upon being turned this pushes the separate member 35 against the vertical walls 34 of the mold tube 11, thus giving a more positive hold between the mold insert portion 24 and the mold tube llo Another embodiment that may be incorporated is the use of optics to line up the two marks 26 on the elongate member 25. A high intensity light source may be used to replace the wire 66 presently in use and this avoids having to string the wire 66 between two fixed positions adjacent the casting machine. -_ 10 --