Metal founding – Including vibrator means – In continuous casting mold
Utility Patent
1998-12-04
2001-01-02
Lin, Kuang Y. (Department: 1722)
Metal founding
Including vibrator means
In continuous casting mold
C164S478000
Utility Patent
active
06167941
ABSTRACT:
FIELD OF THE INVENTION
My present invention relates to a support structure for an oscillating continuous casting mold and, more particularly, to a support structure upon which the continuous casting mold assembly can be mounted and which has a part supporting the continuous casting mold assembly and another part which is fixed.
BACKGROUND OF THE INVENTION
A continuous casting mold assembly with its casting mold, generally of copper, is customarily mounted on a support which allows oscillation of the mold during the continuous casting operation. Without such oscillation, movement of the metal strand through the mold is less effective and, in the course of oscillation, care must be taken to ensure that breakthrough of the melt does not occur since such breakthroughs can only be cleared by expensive and time-consuming operations.
The various approaches to oscillation of the mold have included:
Spring-guided Oscillation with Four Eccentric Drivers
Here the oscillating mold is suspended in a fixed frame by means of four leaf springs and is guided by the springs without play. The mold is therefore able to move in the vertical direction and maintenance and wear in this system are limited. It is however a drawback that the mold can only move in its track in the vertical direction. The guidance in all positions of the mold to be effective at all four corners and the oscillating drive has required two eccentric shafts each carrying two eccentrics for the mold. Not only is this a costly and complex drive arrangement, but the entire eccentric drive lacks the versatility which is often desirable.
Short Lever Oscillation with Two Eccentrics
In this system the mold is guided by two parallelogrammatic linkages in the vertical direction. The drive is effected via a lever which has a lower rocker or crank extended beyond the fixed pivot point. The mold is so guided in its vertical upward and downward movement in a track. This system has the drawback that the base of the system must carry twice the load of the mold and the bearing must pick up not only the guiding forces but also the lifting forces.
As a consequence, the bearings must be massive and the capital cost is high and the maintenance and repair costs. The downtime of such systems may be significant and the maintenance efforts substantial.
Parallelogrammatic Oscillation with Two Hydraulic Cylinders
In this arrangement the mold is supported in two parallelogrammatic linkages for vertical movement. The lifting force is applied directly beneath the mold. During the upward and downward movement, the mold must be guided along its track and also have its position established at each point in time. The driving action requires two cylinders. The disadvantage of this arrangement is that the rotation in the respective bearings is only to a limited angular extent and, while eight expensive bearing assemblies are provide and maintained, the limited movement makes nonuniform wear almost inevitable. The bearings must be protected from the cooling water and lubricated by a central lubricating system and balancing to limit bearing play is practically impossible.
Resonance Mold
In this system, the mold is guided at each side by two leaf springs in a frame. The leaf springs support the mold with their resiliency. The mold is suspended in a manner free from play and requires no maintenance-intensive bearing. The guidance of the mold as to path and location is not at all problematical. Here however the springs have a great effect on the nature of the oscillation since the spring constants must be very large in order to support the mold. In the simplest case, a sinusoidal oscillation shape with the frequency of the characteristic resonance of the spring/mass system is observed. A defined guidance of the material is possible only with a very stiff spring. With oscillation frequency changes, numerous drawbacks can ensue, including the development of extensively large and noncontrollable reaction forces which can excessively strain the system.
Spring-Guided Oscillation with Hydraulic Drive
In this case the oscillating mold is mounted upon a mold frame and the frame on each side is guided by two leaf springs in a manner similar to that described previously for the resonance mold. The leaf springs have a low spring constant and hence low stiffness. As a result, the mold must continuously be driven in all positions thereof. For this purpose, the drive uses four hydraulic cylinders which are provided directly below the mold. The mold is maintenance-free and free from play in the vertical direction. The hydraulic drive can give rise to different lifting modes. A drawback of this arrangement is that the mold is guided only as to its path in the vertical direction. The establishment of location depends upon effective control of the oscillating drive at all four corners of the mold and hence four hydraulic cylinders must be used for this purpose. The hydraulic control mandates that the four cylinders be operated absolutely synchronously. The control system required for this purpose is both expensive and large.
EP 0 421 560 A1 describes an oscillating device for a continuous casting mold with a rectangular base frame on which two rotatably driven eccentric wheels are arranged in parallel. The eccentrics impart oscillation to the mold.
To ensure an exact movement of the relatively low mass mold, the mold is fixed in an opening of a support plate and below each corner of the support plate a wear plate is provided. The wear plate rests upon an outer ring of an eccentric which is journaled rotatably on the eccentric. In addition, spring rods are disposed parallel to the edges of the support plate. The labor involved in maintenance and generally the cost of such a mounting arrangement because of the maintenance and wear is comparatively high.
EP 0 150 357 describes a guide arrangement for an oscillating extrusion mold in which a mold lifting table is provided to which the mold is affixed by holders, connected by spring elements with a frame. In their intermediate regions the frame carriers are anchored to the frame and have leaf springs with ends affixed to the frame. The lifting table for the mold is connected via an intermediate member with the leaf springs at the leaf spring centers.
Finally, reference is made to DE-OS 22 48 066 which discloses a further device for guiding an oscillating continuous casting mold. In this device the mold is affixed to spring elements which extend transversely to the oscillation direction and are anchored on a support frame. These spring elements are stressed in one direction as a kind of cantilever beam, whereby the mold is affixed at free ends thereof. The spring elements are multilayer spring stacks so constructed and arranged that the bending under the mold weight corresponds to at least the oscillation stroke of the mold.
OBJECTS OF THE INVENTION
It is the principal object of the present invention to provide an improved support arrangement for a continuous casting mold which extends principles set forth in these earlier systems but at least in part overcomes the drawbacks of them.
More specifically it is an object of the invention to provide an improved system for supporting a mold which guarantees a long operating life by reducing play at pivot points and which represents a low maintenance and low wear construction which can be fabricated at low cost and does not develop intrinsic resonances radially which can result in breakdown.
Still another object of the invention is to provide an improved mounting for a continuous casting mold assembly which permits exceptionally precise guidance of the oscillating mass.
SUMMARY OF THE INVENTION
These objects and others which will become apparent hereinafter are attained, in accordance with the invention, in a support for a continuous casting mold which is intended to oscillate and which may be of the type described in the commonly assigned copending application Ser. No. 09/205,501 (Attorney's docket No. 20936) and based upon German national application 197 53 959.9 filed Dec. 5, 1997 and i
Dubno Herbert
Lin Kuang Y.
SMS Schloemann-Siemag AG
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