US3533463A

US3533463A - System for steering a casting belt in a continuous metal casting machine of the drum and belt type

Info

Publication number: US3533463A
Application number: US754056A
Authority: US
Inventors: Robert William Hazelett; Richard Hazelett
Original assignee: Hazelett Strip Casting Corp
Current assignee: Hazelett Strip Casting Corp
Priority date: 1968-08-20
Filing date: 1968-08-20
Publication date: 1970-10-13
Anticipated expiration: 1987-10-13

Description

I tamed States Patent 172] lnventors Robert William Hazelett;

Richard Ilazelett, Malletts, Bay. Vermont [21} Appl. No. 754.056

122 Filed Aug. 20, 1968 145] Patented Oct. 13,1970

[731 Assignee Hazelett Strip-Casting Corporationt Malletts Bay,Winooski. Vermont [54] SYSTEM FOR STEERING A CASTING BELT IN A CONTINUOUS METAL CASTING MACHINE OF 3,336,972 8/1967 Coferet a1 164/2725 Primary Examiner-J. Spencer Overholser Air/slum Examiner-R. Spencer Annear :lllOlHQY-RODBI'ISOU, Bryan. Parmelee and Johnson ABSTRACT: System for steering a casting belt in a continuous metal casting machine of the drum and belt type. herein described. wherein a continuously moving mold space is defined between the periphery of a revolving drum and an endless belt which envelopes approximately half the circumference of the drum. ldler wheels apply tension and provide guidance and support for the casting belt. This invention ena bles steering an advantageously thin casting belt in proper alignment on flangeless wheels while at the same time applying adequate tension to the casting belt to prevent leakages of the molten material being cast. This invention enables very thin casting belts to be used which yields the advantages of more effective cooling, less belt distortion, longer belt life. and longer life of the casting drum and a more uniformly cooled quality cast product. In the illustrative embodiment the steering is accomplished by twisting the axis of the exit pulley wheel about a pivot P positioned near the inside or rear edge of the casting belt, the pivot axis lying approximately in the same plane as the tangent point at which the belt coming from the rim of the casting drum contacts the exit wheel. thus. maintaining the thin belt centered on flat, flangeless, contact surfaces ofthe pulley wheels.

Patented Oct. 13,1970

Sheet of 2 INVENTORS. Q m 1921562??? BY 34.671072? M56262? NORA/5Y5,

Roller? Wilda m 3? v v:

Patented Oct. 13, 1970 3,533,46

Sheet 2 012 SYSTEM FOR STEERING A CASTING BELT IN A CONTINUOUS METAL CASTING MACHINE OF THE DRUM AND BELT TYPE In a continuous metal casting machine of the drum and belt type such as described herein prior to this invention, the casting belt has been guided by flanges on the outside edges of the respective idler wheels and/or casting drum. However, this arrangement has experienced a great many difficulties for many years and has restricted the commercial usages of this drum and belt type machine. The flanges cause considerable wear and buckling of the edges of the belt which damages the rim of the casting drum. The casting belt must be flat and held firmly against the rim of the casting drum to prevent leakage of the molten metal.

In drum and belt type casting machines it is desirable to use a belt which is thin because the belt is flexed in one direction when it passes around the casting drum and then it flexes in the opposite direction when it passes around the three idler wheels. The belt is revolving continuously, and therefore it is repeatedly flexed in one direction and then in the other, therefore, the flexural stresses would be reduced and the belt life greatly extended by using a thin belt. However, because of the necessity in the prior art to use flanges to steer the casting belt, it has been necessary to use a thicker casting belt. When attempts have been made in the prior art to use a thin belt under adequate belt tension, it rapidly wears along its edges where they engage the flanges. It has a tendency to climb the flanges as it enters the wheels, thus distorting, tearing or rolling over the edges of the belt. 7

In order to minimize these problems the prior art has used a relatively thick belt (over 0.060 of an inch). However, a thick belt interferes with effective uniform cooling of the molten metal and is more expensive than a thin belt. Also, a thick belt can soon fail from excessive flexural stresses and heat distortion.

In view of these disadvantages of a thick belt, we prefer a thin belt of a thickness of less than 0.060 of an inch. Among other reasons, we prefer a thin belt because we find that a relatively. thin belt can be more effectively and uniformly cooled and so is the cast product; there is less distortion of the belt, providing a more uniform quality product, and the belt has a considerably longer life.

This problem of maintaining the casting belt evenly on uncrowned wheels without wear and damage to its edges, has remained unsolved for some time and much effort and expense has been expended to find a way of preventing this rapid deterioration of the casting belt.

Accordingly, it is an object of this invention to provide apparatus for steering the casting belt in proper alignmenton wheels having flat, cylindrical, uncrowned contact surfaces, without the use of flanges, and at the same time apply adequate tension to a thin belt without creating leakages between the casting belt and the casting wheel.

In this specification and in the accompanying drawings are described and shown a continuous casting machine embodying the present invention, but it is to be understood that this illustrative example of a presently preferred embodiment is not intended to be exhaustive nor limiting of the present invention, but on the contrary is givenfor purposes of illustration in order that others skilled in the art may fully understand the invention and the manner of carrying out the invention in practical use and so that they will understand how to utilize equivalents of the elements shown as may be best suited to the conditions of various particular continuous casting installations.

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

FIG. 1 is a front elevational view of a casting machine of the drum and belt type embodying the steering apparatus of the present invention;

FIG. 2 is a partial sectional plan view ofthe exit wheel ofthe casting machine shown in FIG. 1, as seen from the direction 2-2 in FIG. land drawn on a slightly enlarged scale;

FIG. 3 is an enlarged front elevational viewof the stand on which the exit wheel is mounted as seen at the upper left in FIG. 1; and

FIG. 4 is an enlarged side elevational view of the stand shown as seen from the direction 44 in FIG. 3, illustrating details of the steering mechanism according to the present invention.

As shown in FIG. 1. the continuous casting machine 10 includes a frame base 12 having a casting drum 14 rotatably mounted on the base. A flexible casting belt 16 runs in an arcuate path around approximately one-half of the circumference of the revolving drum 14 and is guided and supported by three

idler pulley wheels

17, 18, and 19. Between the periphery of the revolving drum 14 and the casting belt 16 is defined a moving mold space 20 into which a molten material 22 is poured to be cast. The molten material 22 is seen enter ing the machine by being poured downwardly on the right side of the drum in FIG. 1, and the cast product 25 exits from the left side of the drum in an upward direction.

In order to contain the molten material 22 within the mold space 20 and to cast a product of high quality, it is important that the casting belt 16 be held firmly against the flat rim surfaces of the casting drum 14 and the unflanged contact surfaces of the

pulley wheels

17, 18, and 19. That is, its front face F' must continue in a smooth curvature adjacent to the casting drum 14 and pulley wheels l7, l8, and 19 without any warping or localized distortion. The rear face R of the belt 16 is cooled by a fast traveling liquid coolant 23, for example such as water which may be used in this machine.

The belt 16 is cooled in the region where it encounters the downflowing molten metal 22 by a liquid coolant 23 fed under high pressure through a line 24 into a manifold 26 which is connected to a plurality of nozzles 27 which nest in grooves in the contact surface of the entrance wheel 17 and curve approximately half way around this wheel. In its travel around the casting drum 14, the belt 16 is cooled by means of a coolant supplied to a header 28 extending in an arc concentric with the axis of the drum l4 and located near one edge of the belt 16. The coolant is supplied under pressure to the header 28 through a plurality of lines 32 and is applied against the rear surface R" of the belt at an angle so that the coolant impinges to spread out and form a fast travelling film (not shown) moving transversely across the face R". The header 28 is made in three sections joined by flanges 30. The arcuate header 28 is mounted on the frame 12 by a plurality of supports 34. The, method and apparatus used for cooling the casting belt 16 is shown and described in greater detail and is claimed in our copending application, Ser. No. 542,566, filed Apr. 14, 1966, now US. Pat. No. 3,429,363, the disclosure of which is incorporated herein by reference.

As shown in FIG. 1, the molten material 22 is supplied from an insulated pouring container or tundish 36 and feeds down through a spout 38 into the input region or entrance 40 to the mold space 20. This machineis particularly adapted for continuously casting molten metal, such as aluminum, steel and copper. The cast product 42 is led out of the machine at a point which is on the opposite side from the entrance 40, i.e., adjacent to the exit pulley wheel 18.

In following the path described by the casting belt 16 near the entrance 40, it is seen that the rear face R" describes a concave curve as it turns around the entrance wheel 17; then the belt flexes through-a reverse curve or line of inflection along a transverse line, and then the rear face R" describes a convex curve as it runs around the drum 14. After the belt has traveled approximately half way around the circumference of the casting drum 14, it exits from the drum and reverses its flexure so as to describe a concave curve as it turns around the pulley 18 and then downward at an angle, then curving around pulley wheel 19 and back up at an angle to pulley wheel 17, as shown by the arrows in FIG. 1. The converse of these directions of flexure occur with respect to the front face F.

Referring also to FIGS. 2. 3 and 4, the steering apparatus of the present invention includes a stand 44, including an upper portion 46 and a lower portion 48, which is fastened to the frame base 12 of the casting machine 10. The upper stand portion 46 is pivotally mounted on the lower stand portion 48 by means of a pivot "P near the inside (rear) edge of the exit pulley 18, approximately in the plane of the tangent point of contact of the belt l6 with the drum 18.

As seen in FIG. 2 the contact surface of the exit pulley wheel 18 is flat without any flanges thereon and the belt I6 engages this contact surface as it passes around the pulley wheel 18. The casting belt 16 is steered by twisting the axis of the exit pulley wheel 18 with respect to the axis of the remaining

pulley wheels

17 and 19. This twisting of the axis of the exit wheel 18 is accomplished by turning the upper stand portion 46 about the pivot "P as will be explained in detail further below.

The exit pulley wheel 18 is carried by a rotatable shaft 50 mounted in a-bearing member 52 secured to a plate 54 by a series of bolts 55. The back end of the bearing member 52 is en closed in a housing 56, closed at the opposite end by a member 58 with a brace 60 holding the plate 54in place.

As shown in FIGS. 1 and 2, there are a pair of eccentrics 62 and 64. Eccentric 62 is journaled in a bearing block 63 secured to the upper stand portion 46, and the eccentric 64 is journaled in a bearing block 65 secured to the lower portion 48 of the stand 44. Specifically, the bearing block 63 is secured to a plate 70 forming the bottom of the upper stand portion 46, and the other bearing block 65 is secured to the side of the pedestal frame 49 of the lower stand portion 48. As can be seen, the eccentric 64 has a smaller eccentricity than eccentric 62. The larger eccentric 62 is used for initial adjustment to'center the casting belt on the pulley wheels l7, l8, and 19, while eccentric 64 is for continuously steering the endless casting belt I6 on the flat contact surfaces of the wheels.

In making the initial adjustment to center the casting belt, the main drive (not shown) is placed in operation to rotate the casting drum 14, which causes the belt 16 to travel along its path as seen in FIG. 1 passing around the drum and around the three idler wheels l7, l8 and 19. As the belt 16 is revolving a large wrench is used to turn the eccentric 62 until the belt 16 is centered on the flangeless contact surfaces of the three pulley wheels. This adjustment is made while the other eccentric 64 is in the middle of its operating range. After the initial adjustment is completed, a lock screw 67 is tightened to hold the eccentric 62 in place. A similar lock screw 67 is provided to lock the other eccentric 64 temporarily during initial adjustment. During casting operation the lower eccentric 64 is actuated by steering drive means 68 shown as a handle lever. This handle lever 68 may be operated manually to steer the casting belt or the steering drive means 68 may be actuated by a hydraulic cylinder and piston mechanism 69 having its piston rod pivotally connected at 71 to the lever 68, the cylinder being pivotally secured at 73 to the pedestal frame 49. A sensing mechanism (not shown), such'as a switch having a finger lightly touchingthe edge of the belt 16, serves to sense the position of the belt for automatically controlling the cylinder 69. 1

Referring to FIGS. 2 to 4, it is seen that the eccentrics 62 and 64 are connected by a link member 66 which engages eccentric portions of the eccentrics 62 and 64. By turning the eccentric 62 or 64, the bearing block 63 is pulled by the link member 66 either toward or away from the bearing block 65.

When the bearing block 63 is pulled generally toward the bearing block 65, then the upper stand portion 46 is turned in a clockwise direction C (FIG. 2) about the pivot P. This turning movement of the upper stand portion twists the axis of the shaft 50 of the exit wheel 18 in a clockwise direction C with respect to the axes of the other pulley wheels and drum. When the bearing block 63 is pushed generally away from the bearing block 65, then the upper stand portion 46 and the axis of the shaft 50 is twisted in a counterclockwise direction D about the pivot P. As can be seen with this arrangement, the axis of the exit wheel 18 can be twisted in either direction with respect to the axes of the other pulleys and the drum and thereby cause the belt 16 to be displaced in either direction across the surfaces of pulleys l7 and 19 to maintain the belt properly aligned on the wheels.

The angular movement C or D about the pivot P at which the axis 50 of the exit wheel 18 is twisted about the pivot P is approximately 1 in either direction, 1.6., i: I", from the neutral position. The neutral position is that in which the axis 50 of the wheel 18 is parallel with the axes of the other wheels and drum. After the belt has been initially centered, the steering drive means 68 is operated from time to time whenever the belt begins to creep forwardly or backwardly along the contact surfaces of the wheels I7, 18 and 19. that is, whenever it begins to deviate from its center position.

Twisting the axis 50 of the exit wheel 18 causes the belt to follow a new path as it revolves about approximately one-half of the circumference of the wheel 18. This new path causes the belt to displace itself, i.e., to creep slowly, in an axial direction along the contact faces of the other pulley wheels, thus counteracting the deviation so as to return the belt to the center position. Twisting the axis 50 in a clockwise direction C" causes the belt 16 to displace slowly backwardly (away from the reader in FIG. 1). Conversely, twisting the axis 50 in a counterclockwise direction D" causes the belt to displace slowly forwardly (toward the reader in FIG. 1).

As shown in FIGS. 2 to 4, the upper stand portion 46 and lower stand portion 48 are arranged so the upper portion 46 slides over the lower p0rtion 48. The upper portion 46, being mounted on a steel bearing plate 70 which slides over a friction reducing porous bronze oil-impregnated bearing plate 72 resting on top of a steel bearing plate 74 at the top of the pedestal frame 49. The thin friction reducing plate 72, such as a bronze plate, is interposed between

plates

70 and 74 to reduce the friction between them when the upper portion 44 is being pivoted in the directions C" or D".

In order to hold down the upper plate 70, to counteract the weight of the wheel 18 and shaft 50 and tension force of the belt 16 being exerted on it, a retainer strip 76 is provided which is secured at each end to the lower plate 74 by means of bolts 78. As can be seen, the extent to which the plate 70 can pivot in alternate directions is limited by the bolts 78.

It is noted that as an alternative the entrance or first pulley wheel 17 may also be arranged to have its axis twisted, i.e., arranged like the exit pulley 18 and with this arrangement, the casting belt 16 could be steered. However, we prefer to use the exit wheel 18 in the steering system because of the presence of the molten metal 22 at the entrance to the casting machine.

In the casting machine as described the belt 16 has a thickness of less than 0.060 of an inch, and when incorporated in the system as described it yields the many advantages described in the introduction as well as being less expensive and lasting much longer than those in the prior art, while producing a more uniformly cooled cast product.

The terms and expressions which we have employed are used in a descriptive and not in a limiting sense, and we have no intention of excluding such elements as are equivalents of the elements of the invention described above and defined within the scope of the appended claims.

We claim:

1. A system for steering the casting belt in a continuous casting machine of the revolving drum and belt type having an endlesscasting belt which runs partially around a revolving drum and is guided and supported by a plurality of pulley wheels and for extending the life of the belt comprising a casting belt having a thickness of less than 0.060 of an inch, said belt having a front face F" engaging approximately one half of the circumference of the drum defining a casting mold between the revolving drum and the'front face of the moving belt, said plurality of pulley wheels having flangeless contact surfaces engaging the rear face R of the belt, frame means for the machine, said pulley wheels being mounted on said frame means with their axes parallel with the axis of the drum, one of said pulley wheels being positioned near the drum for guiding the casting belt with reference to the revolving drum. pivot means pivotally mounting said one pulley wheel, said pivot means having an axis lying in a plane extending in a direction substantially tangentially to the circumference of said one pulley wheel on the side thereof toward the drum for twisting the axis of said one pulley wheel about the axis of said pivot means, for steering the belt to keep it generally centered on the flangeless contact surfaces of said pulley wheels.

2. A system for steering the casting belt in a continuous casting machine as claimed in claim 1 in which said one pulley wheel is the one which serves as the exit pulley wheel for receiving the casting belt after it has traveled around the revolving drum, said pivot means being located near the rear edge of the belt near the region where the belt first engages the flangeless contact surface of said exit pulley wheel.

3. A system for steering the casting belt in a continuous casting machine as claimed in claim 1 including a stand for mounting said one pulley wheel, said stand having a lower portion secured to the frame means of the machine, said stand having an upper portion, said pulley wheel being rotatably mounted upon said upper stand portion, said upper stand portion being slidably mounted upon said lower stand portion upon a slide bearing whose plane extends parallel with the axis of said pulley wheel, said pivot means pivotally interconnecting said upper and lower stand portions, and steering means for sliding said upper stand portion relative to said lower stand portion while pivoting about said pivot means.

4. A system for steering the casting belt in a continuous casting machine as claimed in claim 3 in which said upper stand portion includes a base plate near said slide bearing, retainer means secured to said lower stand portion at a position spaced from said pivot means, said retainer means extending above a portion of said base plate for holding said base plate down to stabilize said upper stand portion. said retainer means providing clearance for said base plate to pivot a limited extent about said pivot means.

5. A system for steering the casting belt in a continuous casting machine as claimed in claim 3, in which said steering means is adapted to slide said upper stand portion about said pivot means though an angle of approximately i l relative to a neutral position.

6. A system for steering the casting belt in a continuous casting machine of the revolving drum and belt type having an endless casting belt which runs partially around a revolving drum and is guided and supported by a plurality of pulley wheels comprising a casting belt having a thickness of less than 0.060 of an inch, said belt having a front face F curving around a substantial portion of the circumference of the drum defining a casting mold between the revolving drum and the front face of the curving belt, said plurality of pulley wheels having flangeless contact surfaces engaging the rear face "R" of the belt, frame means for the machine, said pulley wheels being mounted on said frame means with their axes parallel with the axis of the drum, one of said pulley wheels being positioned near the drum and serving as the exit wheel for receiving the casting belt after it has traveled around the revolving drum, pivot means pivotally mounting said exit pulley wheel, said pivot means being located adjacent the edge ofthe flangeless rim of said exit wheel and the circumference of the drum and steering means for twisting the axis of said exit pulley wheel about the axis of said pivot means, for steering the belt to keep it generally centered on the flangeless surfaces of said pulley wheels.

7. A system for steering the casting belt in a continuous casting machine of the revolving drum and belt type having an endless casting belt which runs partially around the circumference of a revolving drum and is guided and supported by a plurality of pulley wheels, said system comprising a machine frame, a plurality of flangeless pulley wheels mounted on said frame and having their axes parallel with the axis of the drum, a stand having an upper portion on which one of said pulley wheels is rotatably mounted. said upper portion being pivotally connected by pivot means to a lower portion of said stand, said lower stand portion being fastened to said machine frame, said stand being located near the circumference of said revolving drum, said pivot means being positioned on the side of said stand near the circumference of said drum and said one of said pulleys and the pivot axis of said pivot means lying in a plane extending in a direction generally aligned with the direction of the adjacent portion of the belt, and steering means for moving said upper stand portion. back and forth about said pivot means for steering the belt to maintain it centered on said flangeless pulley wheels.

8. A system for steering the casting belt in a continuous casting machine of the revolving drum and belt type as claimed in claim 7, in which said pivot means is located generally behind the rear edge of the casting belt, when viewed from the front of the machine looking in a direction parallel with the axis of the drum.

9. A system for steering the casting belt in a continuous casting machine of the revolving drum and belt type as claimed in claim 8 in which said flangeless pulley wheel mounted on said pivoted stand portion is the exit pulley wheel of the casting machine.

10. A system for steering the casting belt in a continuous casting machine of the revolving drum and belt type as claimed in claim 7 in which the casting belt is a metal belt having a thickness ofless than 0.060 of an inch.