US3882924A

US3882924A - Cast piece supporting apparatus for a continuous casting machine

Info

Publication number: US3882924A
Application number: US419101A
Authority: US
Inventors: Yasuo Fujikawa
Original assignee: Mitsubishi Heavy Industries Ltd
Current assignee: Mitsubishi Heavy Industries Ltd
Priority date: 1972-12-18
Filing date: 1973-11-26
Publication date: 1975-05-13
Anticipated expiration: 1992-05-13
Also published as: CH572775A5; CA994980A; DE2361101A1; DE2361101B2

Abstract

The cast piece supporting apparatus disclosed includes cast piece supporting and cooling members, which are disposed just beneath a mould and movable in the upward and downward directions in synchronism with the upward and downward movements of said mould while encircling the outer peripheral surface of said cast piece. The apparatus also includes driving means for making the cast piece supporting and cooling members either closely contact with, or separate from, said outer peripheral surface of said cast piece, and means for equalizing the lowering speed of said mould to the drawing speed of said cast piece. Upon lowering the cast piece supporting and cooling members, these members are made to closely contact with said outer peripheral surface of said cast piece, while upon raising the same, the members are made to separate from said outer peripheral surface of said cast piece.

Description

United States Patent [1 1 Fujikawa 51 May 13, 1975 [75] Inventor:

[73] Assignee: Mitsubishi Jukogyo Kabushiki Kaisha, Tokyo, Japan [22] Filed: Nov. 26, 1973 [21] Appl. N0.: 419,101

Yasuo Fujikawa, Hiroshima, Japan [30] Foreign Application Priority Data Dec. 18, 1972 Japan 47-126183 Oct. 15, 1973 Japan a 48-114687 [52] US. Cl 164/283 R [51] Int. Cl B22d 11/12 [58] Field of Search..... 164/283, 282, 283 S, 283 M [56] References Cited UNITED STATES PATENTS 2,284,503 5/1942 Williams 164/283 R X 2,818,616 l/l958 Rossi 164/283 R X 3,167,829 2/1965 Hess 164/283 S X 3,515,202 6/1970 Bick 164/283 S X 3,516,479 6/1970 Kurth 164/283 R X 3,730,257 5/1973 Haussner 164/283 M Primary ExaminerFrancis S. Husar Assistant Examiner.lohn S. Brown Attorney, Agent, or FirmCushman, Darby & Cushman [57] ABSTRACT The cast piece supporting apparatus disclosed includes cast piece supporting and cooling members, which are disposed just beneath a mould and movable in the upward and downward directions in synchronism with the upward and downward movements of said mould while encircling the outer peripheral surface of said cast piece. The apparatus also includes driving means for making the cast piece supporting and cooling members either closely contact with, or separate from, said outer peripheral surface of said cast piece, and means for equalizing the lowering speed of said mould to the drawing speed ofsaid cast piece. Upon lowering the cast piece supporting and cooling members, these members are made to closely contact with said outer peripheral surface of said cast piece, while upon raising the same, the members are made to separate from said outer peripheral surface of said cast piece.

8-Claims, 5 Drawing Figures PAJENTED 1 31975 3.882.924

sum 1. m a

j 9 5 EL -f 6 PATENTS] HAY 1 31975 saw 201 5 FIG. 3

CAST PIECE SUPPORTING APPARATUS FOR A CONTINUOUS CASTING MACHINE FIELD OF THE INVENTION The present invention relates, in general, to a cast piece supporting apparatus, and more particularly, to a cast piece supporting and cooling apparatus for a continuous casting machine.

BACKGROUND OF THE INVENTION Generally, in a continuous casting machine, the means chosen for supporting a cast piece just beneath a mould are very important and, depending upon what type of supporting means is used, the generation of break-out accidents, deformation of cast pieces and the like results. Also, a restriction is imposed upon the operating conditions such as a casting speed and the like. Among he known cast piece supporting means in the prior art, a guide system employing apron rolls was conventional. In practice, however, according to this means the casting speed was limited and the generation of break-out accidents just beneath a mould could not be obviated.

Especially, from a demand for a high productivity the recent years, a higher speed has been required for continuous casting machines and thus the thickness of a solidified shell in a cast piece just beneath a mould has tended to become thinner. Therefore, in case of the which are disposed just beneath a mould so as to be movable in the upward and downward directions in synchronism with the upward and downward movements of said mould and so as to encircle the outer peripheral surface of said cast piece, driving means for making said cast piece supporting and cooling members either closely contact with or separate from said outer peripheral surface of said cast piece, and means for equalizing the lowering speed of said mould to the drawing speed of said case piece; and in that upon lowering said cast piece supporting and cooling members, said members are made to closely contact with said outer peripheral surface of said cast piece, while upon raising the same, said members are made to separate from said outer peripheral surface of said cast piece.

These and other objects and features of the present invention will become more apparent with reference to the following description of its preferred embodiments taken in conjunction with the accompanying drawings.

I In the Drawings guide system employing apron rolls, the incidence of blisters in the cast piece due to the inner pressure of molten steel is increased, resulting in enlargement of the risk of generating break-out accidents.

For the above-mentioned reasons, recently, improved systems have been proposed in which the thickness of a solidified shell in a cast piece just beneath a mould is increased, and in which for the purpose of preventing break-out accidents, either a mould is extended in length or a fixed member for supporting and cooling a cast piece (a cooling plate) in disposed just beneath a mould. However practical, satisfactory results have not been attained thereby.

The cause of the failure exists in the shortcomings that in case of extending the length of the mould, a sufficient cooling effect cannot be obtained because of formation of an air gap caused by contraction of a cast piece, wear of the lower end portion of a mould is increased, and also there occurs infiltration of copper into a cast piece because of a prolonged contact between the mould and the case piece, resulting in cracks in the case piece, and that in the case of employing a fixed member for supporting and cooling the case piece, the cooling effect is reduced because of an unavoidable gap between said member and the cast piece, and wear of said member for supporting and cooling the case piece per se is rapid, resulting in necessity of a lot of labor for the maintenance of said member.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a cast piece supporting apparatus which is improved with respect to the above-referred shortcomings, which is suitable for high speed casting, and which can prevent break-out accidents.

One feature of the present invention is to provide a cast piece supporting apparatus for a continuous casting machine, characterized in that said apparatus comprises cast piece supporting and cooling members,

FIGS. 1 through 3 show one preferred embodiment of the present invention, FIG. 1 being a longitudinal cross-section View, FIG. 2 being a transverse crosssection view taken along line 11-11 in FIG. 1, and FIG. 3 being a diagrammatic view showing means for moving a mould'as well as a cast piece supporting apparatus according to the present invention in the upward and downward directions; and

FIGS. 4 and 5, respectively, show transverse crosssection views of alternative embodiments of the present invention.

Now one preferred embodiment of the present invention will be described in detail with reference to FIGS. 1 to 3 of the drawings. v

A cast piece supporting apparatus according to the present invention consists of cast piece supporting and cooling members 4 adapted to be moved, hydraulic cylinders 5 for making said cast piece supporting and cooling members 4 either closely contact with or separate from a cast piece 11, spray tubes 9 and spray nozzles 10 for cooling said cast piece supporting and cooling members 4, and a support frame 3 (consisting of annular members 3 and upright members 3") for supporting all the above-referred members. The support frame 3 is fixedly secured to the bottom end of a mould 1, so that the whole of the cast piece supporting apparatus can reciprocate in the upward and downward directions in synchronism with the upward and downward reciprocating motion 2a-2b of the mould l. (The structure for performing this reciprocating motion will be described later.) The cast piece supporting and cooling member 4 is made of an iron plate or a cooper plate, and either it is cooled by injecting thereagainst coolant water by means of the spray pipes 9 and the spray nozzles 10 provided behind said member or it is formed to have a water-cooled jacket structure, so that said member 4 is adapted to cool the cast piece when it is brought in close contact with the cast piece 11. Thus, in the illustrated embodiment, the above-referred spray tubes 9 and spray nozzles 10 form cooling means B for the cast piece supporting and cooling members 4.

A cast piece supporting and cooling member 4 is provided for eachouter peripheral surface of the cast piece 11, and each is.mounted on the upright members 3" of the suppor't'frame through pin joints 6. This pin joint 6 is formed to have an elongated hole which enables the cast piece supporting and cooling member 4 to be displaced in its forth and back directions 7a-7b. In addition, to the cast piece supporting and cooling member 4 for each peripheral surface of the cast piece 11 are connected two, upper and lower, hydraulic cylinders' 5, and provision is made such that the cast piece supporting members 4 are pressed against or separated from the case piece 11 by simultaneously actuating all these hydraulic cylinders 5. Thus, in the illustrated embodiment, the above-referred hydraulic cylinders 5, pin joints 6, upright members 3", etc. form driving means A for the cast piece supporting and cooling members 4.

The construction of the subject apparatus for reciprocating the whole of the cast piece supporting apparatus in the upward and downward directions in synchronism with the upward and downward reciprocating motion 2a-2b of said mould 1 and for simultaneously pressing or separating the cast piece supporting and cooling members 4 to or from the cast piece 11, is diagrammatically shown in FIG. 3. In this figure, reference numeral 23 designates a plurality of hydraulic cylinders for supporting and vertically reciprocating the mould l, which hydraulic cylinders are adapted to be fed with pressurized oil from a hydraulic unit consisting of an oil tank 32, a filter 31, an oil pump 28 driven by an electric motor 29, a check valve 30,

relief valves

25, 27 and 36, a transfer electromagnetic-valve 26, etc., and further there is provided a differential transformer 24 for detecting the upper and lower limit positions of the mould 1, so that the mould 1 is caused to reciprocate vertically with a predetermined amplitude by. switching the transfer electromagnetic-valve 26 in said hydraulic unit in response to the detection of the upper and lower limit positions of the mould l by means of the differential transformer 24. More particularly, when the mould 1 comes to its lower limit position, the differential transformer 24 detects said lower limit position, and in response to the detected electrical signal 33 (represented by a dash line in FIG. 3) the transfer electromagnetic-valve 26 is switched to its position 26a as repesented in FIG. 3. Consequently, the pressurized oil fed from the oil tank 32 by means of the hydraulic pump 28 is supplied to the hydraulic cylinders 23 and to the other hydraulic cylinders for driving the cast piece supporting and cooling members through a hydraulic circuit 34, so that the mould 1 is raised in the direction 2a, while the cast piece supporting and cooling members 4 are displaced in the direction 7b and thereby separated from the cast piece 1 l. The extent of this displacement may be of the order of a few milimeters. Then the hydraulic pressure required for pushing up the mould 1 can be appropriately regulated by means of the relief valve 36 so that the mould 1 may be raised in the direction 2a at the highest permissible speed.

Thus, when the mould 1 has reached the upper limit position, the differential transformer 24 detects that fact, and in response to the detected electrical signal 33' the transfer electromagnetic-valve 26 is switched to its position 26b opposite to the illustrated position. As a result, the pressurized oil is supplied to the hydraulic cylinders 5 through a hydraulic circuit 35, so as to actuate said hydraulic cylinders 5 in the, opposite direction (in the direction 7a to the aforementioned case, for pressing the cast piece supporting afntf cooling members 4 against the cast piece 11. The pressing force exerted by the hydraulic cylinders in this case can be preset at such a value that said pressing force is sufficient to prevent blisters of the cast piece 11 and yet the cast piece 11 is not crushed with an excessive force, by appropriately regulating the hydraulic pressure of said pressurized oil by means of the relief valve 25.

In this case, the mould 1 freely falls under its own gravity because the hydraulic circuit 34 is connected back to the oil tank owing to the switching of the transfer electromagnetic-valve 26 to its position 26b. However, the lowering speed of the mould l in the direction 2b can be regulated by appropriately adjusting the hydraulic pressure of the back flow in the hydraulic circuit 34 by means of the relief valve 27, so that the lowering speed of the mould l in the direction 2b may be completely equalized to the predetermined drawing speed preselected in a cast piece drawing apparatus, not shown. Thus, in the illustrated embodiment, the above-referred differential transformer 24, transfer electromagnetic-valve 26, relief valve 27, hydraulic circuit 34, etc. form means for equalizing the lowering speed of the mould 1 to the drawing speed in the cast piece drawing apparatus. Consequently, the cast piece supporting and cooling members 4 supported by the mould 1 via the support frame 3 can reciprocate in the upward and downward directions in synchronism with the upward and downward movements 2a-2b of the mould 1, said members 4 rising as separated from the cast piece 11 when the mould 1 is raised in the direction 2a, while said members 4 lowering at the same speed as the drawing speed of the cast piece 11 as it is brought in close contact with the outer peripheral surface of the cast piece 11 under an appropriate pressing force thereagainst when the mould 1 is lowered in the direction 2b, whereby said cast piece supporting and cooling members 4 can support and guide the cast piece 11 without being accompanied with a relative slip between the cast piece 11 and said members 4 and also it can achieve a sufficient cooling effect upon the cast piece 11. In this connection, although said cast piece supporting and cooling members 4 separate from the cast piece 11 during their upward movement and so their cooling effect is suppressed during this period of time, the overall cooling effect is not so much reduced because their rising speed is preset at the highest permissible speed as described previously. In addition, there are provided a pair of guide rolls 8 on the annular member 3' at the bottom end of the support frame 3 to prevent the cast piece 11 from bending owing to unbalanced pressing forces exerted by the cast piece supporting and cooling members 4. Further, in FIG. 1, reference numeral 13 designates a plurality of pairs of apron rollers disposed beneath said guide rolls 8.

In the apparatus illustrated in FIGS. 1 to 3, molten steel poured into the mould 1 is cooled as it makes contact with the water-cooled inner wall of said mould, resulting in formation of a solidified shell at its surface portion to form a cast piece 11, and then said cast piece enters the cast piece supporting apparatus according to the present invention while it is drawn from the mould 1 at a predetermined drawing speed by means of a cast piece drawing apparatus, now shown. In this apparatus, since the mould 1 is reciprocating in the upward and downward directions 2a-2b, and especially since during the downward movement in the direction 2b the mould l is lowered at a speed exactly equal to the drawing speed of the cast piece 1 l, the cast piece supporting apparatus fixedly secured to said mould 1 also reciprocates in the upward and downward directions integrally with the mould 1, and during its downward movement it is lowered at a speed exactly equal to the drawing speed of the cast piece 11.

Also in the illustrated apparatus, owing to the actuation of the hydraulic cylinder 5, the cast piece supporting and cooling members 4 of the cast piece supporting apparatus are displaced in the direction 70 during their downward movement and brought in close contact with the outer peripheral surfaceof the'cast'piece 11 for preventing blisters of said cast'piece' l 1 and for cooling the same, whereas during their upward movement said members 4 are displaced in the direction 7b for sepa' rating from the outer peripheral surface of said cast piece 11.

As described, the cast piece supporting and cooling members 4 are pressed against the outer peripheral surface of the cast piece 11 only during the downward movement in the direction 2b of said members 4 caused by the vertical reciprocating motion of the mould l, and owing to the heat conduction through the close contact between the cast piece 11 and said members 4, the cast piece 11 can be well cooled. Subsequently, when the mould 1 has reached its lower limit position and begins to rise in the direction 2a, the cast piece supporting and cooling members 4 are separated from the cast piece 11. As a result, friction would never occur between the cast piece 11 and the cast piece supporting and cooling members 4, and so there never occur the increase of the drawing resistance and the wear of the cast piece supporting and cooling members 4.

The cast piece 11 drawn from the mould 1 and passed through the cast piece supporting and cooling members 4 in the above-described manner, is conveyed to the subsequent roller aprons 13 as it is drawn at a fixed speed in the direction shown by an arrow 12, and thereby it is successively cooled to promote solidification until it is finally finished as a complete product.

The above-described cast piece supporting apparatus can be subjected to modifications in various manners according to the cross-section dimension of the cast piece. One example of modification of the apparatus as applied to a billet cast piece having a small crosssection, is illustrated in FIG. 4. In this case, the cast piece supporting and cooling member 14 is formed to have an L-shaped cross-section so that one such member may support two surfaces of the cast piece 21, the operation for pressing and separating said members 14 to and from the cast piece 21 is carried out by means of hydraulic cylinders 15 disposed at diagonally opposed positions, and spray tubes 16 are provided for the respective back surfaces of said members 14 so as to cool the cast piece supporting and cooling members 14 by direct spraying.

An alternative modification of the subject apparatus as applied to a slab cast piece 22 having a large crosssection, is illustrated in FIG. 5. In this case, the slab cast piece 22 has its wider opposed side surfaces only supported by guide bars 17 mounted on movable frame members 18, and the guide bars 17 are pressed against and separated from the cast piece 22 via said movable frame members 18 by the actuation of hydraulic cylinders 19. In this particular embodiment, the cooling of the cast piece 22 is carried out by directly spraying coolant water against the surface of the cast piece by means of nozzles provided on spray tubes 20 and on the movable frame members 18.

Since the present invention has the aforementioned features and functions, the following practical effects and'advantages could be attained by the present invention:

1. Since the cast piece supporting and cooling members are lowered at a speed equal to the drawing speed of the cast piece and under a condition of closely contacting with the outer peripheral surface of the cast of the drawing resistance can be also obviated.

While the present invention has been described above in connection to its preferred embodiment, it should be clearly understood that the description was made only by way of example and not in a limiting sense.

I claim:

1. In apparatus for carrying out a continuous casting process wherein molten metal is continously moulded into a cast piece which is supported and cooled, and is drawn at a selected speed from downstream of where the cast piece is moulded, supported and cooled,

a cast piece supporting apparatus for a continuous casting machine for drawing the cast piece, comprising:

a downwardly opening mould;

means connected to said mold for cyclically vertically raising the mould faster than the selected drawing speed to an upper position and for permitting the mould to descend to a lower position as a cast piece issues downwardly therefrom whereby the mould is vertically reciprocated;

said means connected to said mold including means for regulating the speed of descent of the mould to equalize the speed of descent of the mould with the selected speed 'of drawing of the cast piece;

cast piece supporting means including plate means engageable with the periphery of the cast piece adjacent where the cast piece issues from the mould;

means co-mounting the cast piece supporting means with the mould for vertically reciprocating the cast piece support means in synchronism with the vertical reciprocation of the mould;

means for cooling the' cast piece located adjacent where the cast piece issues from the mould; and

means connected to said plate means for laterally moving the plate means into and out of engagement with the cast piece in synchronism with the vertical reciprocation of the mould according to a plan wherein the plate means are engaged with the cast piece so long as the mould is lowering and are retracted out of contact with the cast piece so long as the mould is being raised.

2. The cast piece supporting apparatus of claim 1 wherein the cooling means are co-mounted with the cast piece supporting means for vertical, reciprocating movement therewith.

3. The cast piece supporting apparatus of claim 1 wherein the cooling means include cooling fluid spray nozzle means aimed to spray cooling fluid on the plate means of the casting piece support means.

4. The cast piece supporting apparatus of claim 1 wherein the cooling means include cooling fluid spray nozzle means aimed to spray cooling fluid directly on the cast piece.

5. The cast piece supporting apparatus of claim 1 wherein the mould is of rectangular internal transverse cross-section and the plate means are constituted by four plates positioned to engage corresponding sides of the cast piece;

the cooling means including cooling fluid spray nozzle means aimed to spray cooling fluid on the four plates and between adjacent plates directly onto the cast piece.

6. The cast piece supporting apparatus of claim 1 wherein the mould is of rectangular internal transverse cross-section and the plate means are constituted by two'L-shaped plates each positioned to engage two adjacent corresponding sides of the cast piece.

7. The cast piece supporting apparatus of claim 1 wherein the mould is of oblong rectangular internal transverse cross-section and the plate means are constituted by a plurality of guide bars positioned to engage the two opposite wider corresponding sides of the cast piece,

8. The cast piece supporting apparatus of claim 1 wherein the means for cyclically raising the mould and for permitting the mould to descend and the means for laterally moving the plate means comprise hydraulic piston and cylinder means arranged in a hydraulic fluid circuit having means for pressurizing the hydraulic fluid and valving for controlling the direction of movement of the piston means within the cylinder means; the valving including limit switch means for ascertaining when the mould has been raised to said upper posit-ion and when the mould has descended to said lower position, and for switching said valving in response to such ascertainment; and wherein the regulating means includes control valve means adjustable to control the flow of the hydraulic fluid for adjusting the resistance the hydraulic fluid presents to descent of the mould whereby the rate of descentof the mould may be equalized with the selected drawing speed;

Claims

1. In apparatus for carrying out a continuous casting process wherein molten metal is continously moulded into a cast piece which is supported and cooled, and is drawn at a selected speed from downstream of where the cast piece is moulded, supported and cooled, a cast piece supporting apparatus for a continuous casting machine for drawing the cast piece, comprising: a downwardly opening mould; means connected to said mold for cyclically vertically raising the mould faster than the selected drawing speed to an upper position and for permitting the mould to descend to a lower position as a cast piece issues downwardly therefrom whereby the mould is vertically reciprocated; said means connected to said mold including means for regulating the speed of descent of the mould to equalize the speed of descent of the mould with the selected speed of drawing of the cast piece; cast piece supporting means including plate means engageable with the periphery of the cast piece adjacent where the cast piece issues from the mould; means co-mounting the cast piece supporting means with the mould for vertically reciprocating the cast piece support means in synchronism with the vertical reciprocation of the mould; means for cooling the cast piece located adjacent where the cast piece issues from the mould; and means connected to said plate means for laterally moving the plate means into and out of engagement with the cast piece in synchronism with the vertical reciprocation of the mould according to a plan wherein the plate means are engaged with the cast piece so long as the mould is lowering and are retracted out of contact with the cast piece so long as the mould is being raised.

5. The cast piece supporting apparatus of claim 1 wherein the mould is of rectangular internal transverse cross-section and the plate means are constituted by four plates positioned to engage corresponding sides of the cast piece; the cooling means including cooling fluid spray nozzle means aimed to spray cooling fluid on the four plates and between adjacent plates directly onto the cast piece.

6. The cast piece supporting apparatus of claim 1 wherein the mould is of rectangular internal transverse cross-section and the plate means are constituted by two L-shaped plates each positioned to engage two adjacent corresponding sides of the cast piece.

7. The cast piece supporting apparatus of claim 1 wherein the mould is of oblong rectangular internal transverse cross-section and the plate means are constituted by a plurality of guide bars positioned to engage the two opposite wider corresponding sides of the cast piece.

8. The cast piece supporting apparatus of claim 1 wherein the means for cyclically raising the mould and for permitting the mould to descend and the means for laterally moving the plate means comprise hydraulic piston and cylinder means arranged in a hydraulic fluid circuit having means for pressurizing the hydraulic fluid and valving for controlling the direction of movement of the piston means within the cylinder means; the valving including limit switch means for ascertaining when the mould has been raised to said upper position and when the mould has descended to said loWer position, and for switching said valving in response to such ascertainment; and wherein the regulating means includes control valve means adjustable to control the flow of the hydraulic fluid for adjusting the resistance the hydraulic fluid presents to descent of the mould whereby the rate of descent of the mould may be equalized with the selected drawing speed.