Mold For Use In Continuous-casting Of Metals

Abstract

A mold for use in continuous casting of metals in which the backup plates are fastened to the liner by a novel means. The outside faces of the liner have a series of vertical ribs which define with the backup plates a plurality of water-circulation passages. Certain of the ribs have laterally directed lips under which metal strips are inserted. The strips carry studs which extend through the backup plates. Nuts are threadedly engaged with the studs and drawn up tightly. The water-circulation passages are unobstructed and all have the same hydraulic diameters, which are constant throughout the length of the passages. Hence water flowing through each passage has the same velocity.

Description

This invention relates to an improved mold for use in continuous-casting of metals.

A conventional mold used in continuous-casting includes a liner of metal which conducts heat readily (usually copper) and backup plates (usually steel) fastened to the outside of the liner. Water-circulation passages are formed between the liner and backup plates. Both ends of the liner are open. Liquid metal is poured continuously into the upper end, and a casting, which at this stage has only a thin solidified skin and a liquid core, emerges from the lower end. A number of ways are known for fastening the backup plates to the liner. For example, studs may be welded or threaded into the liner, and nuts may be threadedly engaged with the studs outside the backup plates. It is known also that either the outside faces of the liner or the inside faces of the backup plates or both may be ribbed to form the water-circulation passages. Another known fastening means, used in molds which have ribbed liners, is a series of T-bolts inserted in some of the passages between ribs. The ribs alongside these passages have laterally directed lips to retain the heads of the T-bolts. This arrangement has the disadvantage that the bolt heads partially obstruct the passage and thus interfere with the water flow.

An object of our invention is to provide a continuous-casting mold which embodies improved means fastening the backup plates to the liner.

A further object is to provide, in a mold, a structurally sound connection between a copper liner and steel backup plates, which connection also enables a uniform unobstructed water flow to be maintained through the water-circulation passages.

A more specific object is to provide a mold in which the water-circulation passages are formed between ribs in the liner faces, and the backup plates are fastened with metal strips inserted in certain of the passages and studs fixed to the strips, but in which all passages have equal hydraulic diameters constant throughout their lengths to afford uniform velocity of cooling water.

In the drawing:

FIG. 1 is a partially diagrammatic perspective view, not to scale, of a continuous-casting mold in which is incorporated our improved means fastening the backup plates to the liner;

FIG. 2 is a fragmentary vertical section on line II--II of FIG. 1; and

FIG. 3 is a fragmentary horizontal section on line III--III of FIG. 2.

FIG. 1 shows a continuous-casting mold which may be conventional apart from our improved fastening means. The mold illustrated is for casting relatively wide slabs, and comprises an open-ended one-piece liner 10, a pair of relatively wide backup plates 12 fastened to the wide faces of the liner, and a pair of relatively narrow backup plates 13 fastened to the narrow faces. The backup plates have the usual water inlets and outlets 14 and 15 near the lower and upper edges respectively. The particular mold illustrated is only one example of a mold to which we may apply our fastening means. For example the mold could have a four-piece liner, or it could be of square cross section for casting billets, etc.

As shown in FIGS. 2 and 3, the outside faces of the liner 10 have series of vertical ribs 18, 18a. The backup plate 12 abuts ribs 18 to define therewith a plurality of parallel unobstructed water-circulation passages 19. The ribs 18a have opposed laterally directed lips 20. We insert metal strips 21 from one end under the lips 20. The ribs 19a and strips 21 define additional unobstructed water-circulation passages 19a. Water flows through passages 19 and 19a to cool the liner and solidify a skin on the casting. The strip 21 in each passage may be continuous through the length of the passage, or it may be formed of a plurality of closely abutting segments, as FIG. 2 shows. The latter arrangement has an advantage that it affords less stiffness and allows the mold to expand and contract more readily. The strips carry studs 22, which may be welded thereto or threaded into tapped holes. The studs extend through the backup plates 12 or 13. Nuts 23 are threadedly engaged with the studs outside the backup plates and drawn up tightly to fasten the latter to the liner. The strips and studs may be of any suitable metal, such as steel, since the choice is not critical. Normally friction alone holds the strips in place, but optionally the strips may carry knife edges 24 which bite into the softer metal of the liner lips.

The passages 19 are all of equal width and equal depth. The passages 19a, which accommodate the strips 21, are wider than passages 19 and of less depth. The dimensions of passages 19a are chosen to provide the same hydraulic diameter as passages 19. The hydraulic diameters are constant throughout the length of each passage. Hence water flowing through each passage 19a has the same velocity as the water flowing through each passage 19. The "hydraulic diameter" is defined as follows:

Hydraulic Diameter = 4 .times. Cross-sectional area of passage/Wetted perimeter of passage

The cooling effect of water flowing through an enclosed passage is mainly a function of the water velocity. Hence our invention achieves substantially uniform cooling across the faces of the liner.

The fastening means of our invention is simple and economical. The strips 21 are retained in the passages 19a without welding. We obtain further economy by stud-welding the studs 22 to the strips, in preference to threading them in place. At the same time the fastening means retains the backup plates securely to the liner.

Claims

1. In a continuous-casting mold which includes an open-ended liner of heat conductive metal, and backup plates fastened to the outside faces of said liner, said liner having a series of vertical ribs in its outside faces defining with said backup plates a plurality of parallel unobstructed water-circulation passages, the combination therewith of improved means fastening said backup plates to said liner, said means comprising opposed laterally directed lips formed on certain of said ribs, metal strips inserted in these passages under said lips, the latter ribs defining with said strips additional unobstructed water-circulation passages, studs fixed to said strips and extending through said backup plates, and nuts

2. A mold as defined in claim 1 in which said first-named passages are of equal width and equal depth, and said additional passages are wider and of less depth than the first-named passages, said passages all having equal hydraulic diameters, which are constant throughout the length of the

3. A mold as defined in claim 1 in which said strips are formed of abutting

4. A mold as defined in claim 1 in which said strips are continuous through

5. A mold as defined in claim 1 in which said strips are retained in said

6. A mold as defined in claim 1 in which said strips carry knife edges which bite into the metal of said lips.