US3310849A

US3310849A - Continuous metal casting apparatus

Info

Publication number: US3310849A
Application number: US432773A
Authority: US
Inventors: Hazelett Robert William; Hazelett Richard
Original assignee: Hazelett Strip Casting Corp
Current assignee: Hazelett Strip Casting Corp
Priority date: 1965-02-15
Filing date: 1965-02-15
Publication date: 1967-03-28
Anticipated expiration: 1984-03-28

Description

March'28, 1967 R. w. HAZELETT ETAL 3,319,849

CONTINUOUS METAL CASTING APPARATUS 4 Sheets-Sheet 1 Filed Feb. 15, 1965 A'KBERT WILLIAM H RIC M AZELETT H D HA/EL TT AT RN YS v March 23, 1967 R. w. HAZELETT ETAL 3,310,849

CONTINUOUS METAL CASTING APPARATUS Filed Feb. 15, 1965 4 Sheets-Sheet 2 ROBERT WILLIAM HAZELETT D ETT FIG-2 INVENTORS March 1957 R. w. HAZELETT ETAL CONTINUOUS METAL CASTING APPARATUS 4 Sheets-Sheet 3 Filed Feb. 15, 1965 INVENTORS ROBERT WILLIAM HAZELETT RICHAR HA j 0 ,"v:

ATTNEYS j M816}! 1957 R. w. HAZELETT ETAL 3,310,849

CONTINUOUS METAL CASTING APPARATUS 4 Sheets-Sheet 4 Filed Feb. 15, 1965 HAZELETT AZELETT @110 m o M N mm W D /0 N M T I Tmwjwr R m Y R United States Patent CONTINUOUS METAL CASTING APPARATUS Robert William Hazelett, Winooski, Vt., and Richard Hazelett, Austin, Tex., assignors to Hazelett Strip- Casting Corporation, Winooski, Vt., a corporation of Delaware Filed Feb. 15, 1965, Ser. No. 432,773 7 Claims. (Cl. 22-57.4)

This invention relates to machines and processes for casting metal strip directly from molten metal and more particularly for continuously casting wide slabs, thin shapes and metal strips, and the like, between spaced portions of a pair of endless flexible casting belts which are moved along with opposite surfaces of the metal being cast.

The invention is described as embodied in the structure and operation of a continuous strip-casting machine in which the molten metal is fed into a casting region between the spaced portions of a pair of moving flexible casting belts and a continuous strip of solidified metal is delivered from the machine. One of the moving belts is positioned generally above the other, and the spaced portions of the upper and lower belts confine the molten metal in a casting region between them and carry the molten metal along as it solidifies between them. To withdraw the large quantities of heat from the solidifying metal, both the upper and lower belts are cooled by means of rapidly moving substantially continuous films of liquid coolant travelling along against their reverse surfaces adjacent to the casting region. The two casting belts are individually mounted upon a pair of special carriages, and each belt is steered around its carriage in rectangular path while each belt is maintained under high tension.

In the illustrative machine embodying the present invention the two belt carriages each include four main rolls arranged in a generally rectangular pattern having their axes parallel with two of these rolls being positioned at one end of each carriage and the other two at the other end. The flexible casting belt on each carriage is driven around these four rolls in a generally rectangular path, and for steering the belt, the axes of the two rolls vat the exit end of the machine are simultaneously and equally skewed by the belt-steering apparatus.

In this illustrative embodiment of the invention in order to provide for simultaneous skewing of the two rolls, the outer side frame of the carriage is advantageously separated into two sections. One of these frame sections carries the bearings at the ends of these two rolls and is movably mounted so as to skew the two rolls in a direction which is perpendicular to the plane of the casting region.

It is an object of the present invention to provide a continuous casting machine having improved operating characteristics and advantages in use.

In this specification and in the accompanying drawings are described and shown a machine embodying this invention for continuous casting of metal, and various modifications thereof are indicated, but it is to be understood that these are given for purposes of illustration in order that others skilled in the art of metal casting may fully understand the invention and the manner of applying the apparatus in practical use and so that they will understand various embodiments and adaptations of this invention for continuously casting metal.

The various features, aspects, and advantages of the present invention will be more fully understood from a consideration of the following specification in conjunction with the accompanying drawings, in which:

FIGURE 1 is a side elevational view of a continuous casting machine embodying the present invention;

FIGURE 2 is a longitudinal sectional view of the machine;

FIGURE 3 is a side elevational view of one end of one of the belt carriages, illustrating details of the dual roll steering system;

FIGURE 4 is a perspective end view of the portion of the frame of the belt carriage shown in FIGURE 3;

FIGURES 5 and 6 are sectional views of the eccentric steering bearings, taken along the

sectional lines

55 and 66 in FIGURE 3; and

FIGURES 7 and 8 are schematic perspective views illustrating the dual roll steering action.

In the continuous metal casting machine which is shown in the drawings as an illustrative example of the present invention, the molten metal is supplied from an insulated tundish or pouring box 10, as shown in FIG- URE 2 at the input end of the machine. From this tundish 10 the molten metal supply is fed forward be tween the spaced parallel surfaces of upper and lower endless

flexible casting belts

12 and 14, respectively. The molten metal solidifies while being confined between the spaced parallel faces of the two casting belts which move along in synchronism.

These

casting belts

12 and 14 are formed of flexible and heat resistant sheet metal having a relatively high tensile strength, for example, such as cold-rolled lowcarbon sheet steel as described in U.S. Patent No. 3,036,348. In many instances the front faces of the casting belts, which are the surfaces adjacent to the molten metal, are coated with a suitable protective coating or dressing, such as is described in US. Patent No. 2,904,860. In this present machine these belts may have a width of more than 60 inches and have a thickness of the order of 0.050 of an inch.

The two casting belts are supported and driven by means of special upper and lower carriages, which are generally similar and are indicated in FIGURES 1 and 2 at U and L, respectively. Each carriage includes four main rolls for supporting, driving and steering the belt in a generally rectangular path. There are the upper and

lower input rolls

16 and 18, respectively, which are also called the nip rolls. These nip rolls each have deep and closely spaced circumferential grooves therein adjacent to the curving reverse surfaces of the belts with high-velocity curved coolant discharge nozzles 20 nested into these grooves for the purpose of providing intense cooling of the casting belts adjacent to the input.

At the exit end of each carriage are pairs of

steering rolls

22 and 24, 26 and 28, respectively. In order to provide a very effective steering action for the belts, these pairs of steering rolls are mounted so that their axes can both be skewed simultaneously with respect to the other two rolls in the carriage, as will be explained.

The fourth main roll in each carriage is the

belttensioning roll

30 and 32, respectively, which is mounted upon lever arms 34. These arms are tied together by a tube 35 (FIG. 2) and are supported on pivots 36 and are each operated by a fluid cylinder 38 and a piston rod 40 as illustrated in FIGURE 7. When it is desired to tension or slacken the

belt

12 or 14, the corresponding pair of cylinders 38 are actuated. Each tension roll has a resilient layer 42 of rubber engaging the belt. During the operation the two casting belts are driven at the same linear speed, and they are each maintained under a high tension force, for example, such as 10,000 to 20,000 pounds per square inch of cross sectional area of the belt.

It will be noted that three of the main rolls on each carriage have closely spaced circumferential grooves 43 and the fourth one has a resilient rubber layer 42. This construction provides improved operating characteristics because it avoids dimpling of the casting belts by any dirt particles which may pass between the reverse surface of the beit and any of these rolls. The yielding rubber layer or the grooves 43 provide space in which any such dirt particle is accommodated without producing localized distortion and dimpling of the casting belt from the large forces involved.

The moving belts are guided, that is, backed up by a series of parallel rollers 44 so that their opposed front surfaces are held in the desired spaced relationship along the length of the casting region C. These back-up rollers 44 include narrow tapered peripheral ridges engaging the reverse surface of each belt. It will be noted that the first two back-up rollers 45 for each belt are of smaller diameter and have smaller peripheral ridges with their axes positioned more closely adjacent to the belt. These rollers 45 provide multiple points of support for the casting belts in the limited space closely adjacent to the

input rolls

16 and 18. Moreover, these small closely adjacent rollers 45 hold the casting belts firmly against the moving edge darns to prevent leakage of the molten metal near the input. To avoid deflection of these small diameter rollers 45, a rigid back-up bar 46 extends across the machine and has multiple saddle surfaces sitting down against the rollers 45 at spaced points along their length between their peripheral ridges. The rollers 45 and backup bar 46 provide clearance for a coolant layer travelling along the belt issuing from the nozzles 20.

For solidifying the metal in the casting region, heat is withdrawn through each belt by means of a rapidly moving layer of liquid coolant traveling along the reverse surface of the belt. The narrow tapered ridges of the back-up rollers 45 and 44 enable this coolant layer to continue substantially continuously along the reverse surfaces of the belts, as described in detail and claimed in said patents.

As shown in FIGURE 1, this coolant may be supplied from a large reservoir, such as a tank 48 positioned beneath the base frame 50 of the machine. This coolant is suitably pumped through ducts to the nozzles 20 and to coolant application and scoop units 52, which extend transversely of both carriages parallel to the reverse surfaces of the

respective belts

12 and 14. The units '2 serve to maintain the high-speed coolant layer traveling along the reverse surfaces of the belts and are like those which are described in detail and claimed in US. Patent No. 3,041,686 to which reference may be made for further information. The

steering rolls

22 and 26 have deeper grooves 43 for accommodating passage of the coolant layer therethrough, which is then scooped off from the straight flat section of the belt which extends between the 'two steering rollers by means of a scoop 54.

It will be noted from FIGURES 1 and 2 that the two carriages U and L are in cantilevered relationship so that their outboard sides (sides toward the reader in FIG- URES 1 and 2) are free of obstruction so as to facilitate removal and replacement of the casting belts. By releasing the

tension roll

30 or 32, the

respective casting belt

12 or 14 can he slid off from the outboard side of its carriage.

In order to prevent the molten metal from running out in a lateral direction from the casting region C, there are provided a pair of flexible moving edge dams 55 (FIG. I) and 56 (FIG. 2) extending between the casting belts. These dams each comprise numerous steel blocks strung in end-to-end relationship on a continuous flexible strap as described and claimed in US. Patent No. 2,904,860. Whenever the operator desires to change the thickness of the strip being cast, the two edge dams 5S and 56 are slid off from the outboard side of the lower carriage and replaced by a pair of thicker or thinner dams as required.

It will be appreciated that these wide casting belts, each of which is revolving under a high tension may tend to creep axially one way or the other, depending upon any slight difference with respect to its opposite edges, for example, such as slight dilferences in heat expansion,

because such minute eifects become cumulative as the belt continues to revolve. Consequently, it is important to provide positive steering for each belt. In this way, each belt is controlled in position and maintained properly centered on the four main rolls of the carriage.

In order to provide this steering action the outer side frame 58 of each carriage U and L is separated into a main section 59 and a movable exit section 60 which rides against a pair of aligned

slide bearing plates

61 and 62 mounted upon the main section, as seen in FIGURES l, 3 and 4. These slide bearings '61 and 62 extend along a line which is perpendicular to the plane of the casting region C. The inner frame 64 of each carriage is an integral unit as seen in FIGURES 2 and 4. The movable section 60 is secured by a plurality of tie rods 66 (FIGURES 2 and 4) to the integral end portion of the inner frame 64, and these tie rods are arranged to defiect sufficiently for accommodating the steering motion of the end section 60. These tie rods 66 maintain a parallelogram relationship between the movable end section 60 and the end of the inner frame 64. A pair of retainers 67 and 68 (FIGS. 3 and 4) are coupled between the main section 59 and end section 60 so as to prevent this end section'from swinging over away from engagement of the

slide bearings

61 and 62 whenever tension in the casting belt is removed.

The inner ends of the respective pairs of steering rolls 22 and 24, 26 and 28 are held fixed in position by hearing means 72 in the integral inner frame 64, while the outer ends of these rolls are held by bearing means 74 in the movable frame section 60. Accordingly, the axes of the pair of steering rolls in each carriage are simultaneously and equally skewed with respect to the other pair of rolls by movement in a direction perpendicular to the plane of the casting region C.

For moving the end portion 60 there is a forward projection 76 fitting into a ciearance recess 78 in the main frame section 59, and a manually adjustable eccentric shaft 80 (FIG. 5) is journaled in a bearing 81 in this projection 76. A handle 82 is keyed to this eccentric shaft 80 for adjusting the initial position of the end section 60, and a pair of connecting links 84 extend to another eccentric shaft 86 (FIG. 6) is journaled in a bearing 87 in the main frame section 59 near the slide plate 62. A control arm 88 is keyed to this eccentric shaft 86 and is operated by a fluid cylinder 90 and piston rod 92.

It is to be noted from FIGURES 7 and 8 that there is a flat area 94 of the casting belts extending between the pair of steering rolls 22 and 24, 26 and 28. In spite of the presence of this flat area 94, we have found that this steering of a casting belt moving in a generally rectangular path by simultaneously skewing a pair of rolls at one end of the path produces a more effective steering action than in the prior machines wherein only one roll is skewed.

This skewing causes the belt to approach the respective pairs of

rolls

22 and 24, 26 and 28 at a slight deviation from their longitudinal axes. As a result, the belt is caused to shift gradually laterally one way or the other in the desired direction with respect to all four of the rolls as indicated in FIGURES 7 and 8. We have found that in the operation of this machine a smaller total skewing travel is required for a given width of belt to maintain the belt properly positioned than in the prior machines. This is advantageous in minimizing any distortion of the plane of the casting region C while the metal is solidifying therein.

For controlling the operation of the cylinders 90, suitable sensing means, for example such as probes, are used to sense the position of the edges of the respective belts.

From the foregoing it will be understood that the continuous casting machine embodying the present invention as described is well suited to provide advantages in operation, and since many possible embodiments may be made of the various features of this invention and as the apparatus herein described may be varied in various parts, all without departing from the scope of the invention, it is to be understood that all matter hereinbefore set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense and that in certain instances, some of the features of the invention may be used without a corresponding use of other features, all without departing from the scope of the claimed invention.

What is claimed is:

1. A machine for continuously casting molten metal comprising first and second moving flexible belts, means supporting and driving said belts for movement in the same direction at the same speed in spaced face-to-face relationship defining a casting region therebetween including first and second belt carriages, each of said carriages including four main rolls arranged in a generally rectangular pattern for guiding the respective belts along a rectangular path, and belt steering means on each carriage for simultaneously and equally skewing the axes of a pair of said main rolls at one end of each carriage for steering the belts.

2. A machine for continuously casting molten metal comprising first and second moving flexible belts, means supporting and driving said belts for movement in the same direction at the same speed in spaced face-to-face relationship defining a casting region therebetween and for steering said belts including first and second belt carriages, each of said carriages including four main rolls arranged in a generally rectangular pattern for guiding the respective belts along a rectangular path, a pair of side frames in said carriage, said side frames being in spaced parallel relationship for supporting the opposite ends of said four main rolls, one of said side frames being separated into a main section and an end section movably mounted with respect to said main section for motion in a direction perpendicular to the casting region, a pair of said main rolls each being supported at one end by said end section of the side frame, and drive means for moving said end section for simultaneously and equally skewing the axes of said pair of rolls.

3. A machine for continuously casting molten metal comprising first and second moving flexible belts, means supporting, driving and steering said belts for movement in the same direction at the same speed in spaced faceto-face relationship defining a casting region therebetween for receiving molten metal into the input end of the casting region and for discharging solidified metal from the exit end including first and second belt carriages, each of said carriages having four main rolls arranged in a generally rectangular pattern for guiding the respective belts along a rectangular path, a pair of side frames in said carriage, said side frames being in spaced parallel relationship for supporting the opposite ends of said four main rolls, one of said side frames being separated into a main section and an end section at the exit end of the machine movably mounted with respect to said main section for motion in a direction perpendicular to the casting region, a pair of said main rolls at the exit end of the machine each being supported at one end by said movable end section, and drive means for moving said end section for simultaneously and equally skewing the axes of said pair of rolls at the exit end of the machifie for steering the casting belt.

4. A machine for continuously casting molten metal comprising first and second moving flexible belts and apparatus for supporting, driving and steering said belts for movement in the same direction at the same speed in spaced face-to-face relationship defining a casting region therebetween including first and second belt carriages, each of said carriages including four main rolls arranged in a generally rectangular pattern for guiding the respective belts along a rectangular path, a pair of side frames in each carriage, said side frames being in spaced parallel relationship for supporting the opposite ends of said four main rolls, a first one of said side frames being an integral unit and the second side frame being separated into a main section and an end section, movable mounting means between said end section and said main section for movably mounting said end section thereon for motion with respect to said main section in a direction perpendicular to the casting region, a plurality of tie rods extending between said movable end section and said first integral side frame for accommodating movement of said end section, a pair of said main rolls each being supported at one end by said movable end section and at the other end by said first frame, and drive means for moving said end section for simultaneously and equally skewing the axes of said pair of rolls.

5. A machine for continuously casting molten metal comprising first and second moving flexible belts and apparatus for supporting, driving and steering said belts for movement in the same direction at the same speed in spaced face-to-face relationship defining a casting region therebetween including first and second belt carriages, each of said carriages having four main rolls arranged in a generally rectangular pattern for guiding the respec tive belts along a generally rectangular path, a first and a second side frame in each carriage, said side frames being in spaced parallel relationship for supporting the opposite ends of said four main rolls, said first side frame being separated into a main section and an end section, a pair of spaced slide bearings aligned perpendicular to the plane of the casting region and positioned between said end section and said main section for movably mount ing said end section thereon for motion in a direction perpendicular to the casting region, said main section having a recess therein between said pair of slide bearings, said end section having a projection extending into said recess, drive means connected between said main section and said projection, and a pair of said main rolls each being supported at one end by said movable end section and at the other end by said first frame for simultaneously and equally skewing the axes of said pair of main rolls in a direction perpendicular to the plane of the casting region for steering the belt.

6. A machine for continuously casting molten metal comprising first and second moving flexible belts, means for supporting and moving said belts in the same direction at the same speed in spaced face-to-face relationship defining a casting region therebetween for receiving molten metal into the input end of the casting region and for discharging solidified metal from the exit end thereof including first and second belt carriages, each of said carriages having four main rolls arranged in a generally rectangular pattern for guiding the respective belts along a rectangular path, one of said main rolls on each carriage having a resilient coating thereon and tension means movably mounting said one main roll on each carriage for applying a large tension force upon the belt, and the other three main rolls on each carriage having closely spaced circumferential grooves for accommodating the passage of any dirt particles between each belt and the four rolls without dimpling the belt.

7. A machine for continuously casting molten metal comprising first and second moving flexible belts, means for supporting and moving said belts in the same direc tion at the same speed in space face-to-face relationship defining a casting region therebetween for receiving molten metal into the input end of the casting region and for discharging solidified metal from the exit end thereof including first and second belt carriages, each of said carriages having a first main roll at the input end and a second main roll at the exit end for supporting the belt at the input and exit ends of the casting region, coolant application means for flowing coolant against the belt along the casting region, a plurality of back-up rollers extending across behind the belt having spaced narrow peripheral ridges for guiding the belt while accommodating the flow of coolant, a pair of flexible moving edge dams traveling between the belts from input to exit in the casting region, a plurality of smaller diameter back-up rollers closely adjacent to the first main roll each having narrow peripheral ridges, and& rigid back-up bar having a plurality of saddle surfaces engaging said smaller diameter rollers for preventing deflection of said rollers for holding the belt closely adjacent to the moving edge dams immediately behind said first main roll.

References Cited by the Examiner UNITED STATES PATENTS J. SPENCER OVERHOLSER, Primary Examiner.

Rv S. ANNEAR, Assistant Examiner.

Claims

7. A MACHINE FOR CONTINUOUSLY CASTING MOLTEN METAL COMPRISING FIRST AND SECOND MOVING FLEXIBLE BELTS, MEANS FOR SUPPORTING AND MOVING SAID BELTS IN THE SAME DIRECTION AT THE SAME SPEED IN SPACE FACE-TO-FACE RELATIONSHIP DEFINING A CASTING REGION THEREBETWEEN FOR RECEIVIG MOLTEN METAL INTO THE INPUT END OF THE CASTING REGION AND FOR DISCHARGING SOLIDIFIED METAL FROM THE EXIT END THEREOF INCLUDING FIRST AND SECOND BELT CARRIAGES, EACH OF SAID CARRIAGES HAVING A FIRST MAIN ROLL AT THE INPUT END AND A SECOND MAIN ROLL AT THE EXIT END FOR SUPPORTING THE BELT AT THE INPUT AND EXIT ENDS OF THE CASTING REGION, COOLANT APPLICATION MEANS FOR FLOWING COOLANT AGAINST THE BELT ALONG THE CASTING REGION, A PLURALITY OF BACK-UP ROLLER EXTENDING ACROSS BEHIND THE BELT HAVING SPACED NARROW PERIPHERAL RIDGES FOR GUIDING THE BELT WHILE ACCOMMODATING THE FLOW OF COOLANT, A PAIR OF FLEXIBLE MOVING EDGE DAMS TRAVELING BETWEEN THE BELTS FROM INPUT TO EXIT IN THE CASTING REGION, A PLURALITY OF SMALLER DIAMETER BACK-UP ROLLERS CLOSELY ADJACENT TO THE FIRST MAIN ROLL EACH HAVING NARROW PERIPHERAL RIDGES, AND A RIGID BACK-UP BAR HAVING A PLURALITY OF SADDLE SURFACES ENGAGING SAID SMALLER DIAMETER ROLLERS FOR PREVENTING DEFLECTION OF SAID ROLLERS FOR HOLDING THE BELT CLOSELY ADJACENT TO THE MOVING EDGE DAMS IMMEDIATELY BEHIND SAID FIRST MAIN ROLL.