US3080625A

US3080625A - Continuous casting apparatus

Info

Publication number: US3080625A
Application number: US794324A
Authority: US
Inventors: Pearson John; Savage John; Ball Eric
Original assignee: British Iron and Steel Research Association BISRA
Current assignee: British Iron and Steel Research Association BISRA
Priority date: 1958-02-21
Filing date: 1959-02-19
Publication date: 1963-03-12
Anticipated expiration: 1980-03-12

Description

March 12, 1963 j J. PEARSON ETAL 3,080,625

CONTINUOUS CASTING APPARATUS Filed Feb. 19} 1959 r g lza 2 er: 2 V 26 29 12L 0 o 28 4 2 29 l6 0 25 23 J 1 E L I46 27 Uite States tet 3,080,625 CONTINUOUS CAs'iiNG APPARATUS John Pearson, Dore, Shefiield. John Savage, Addlestone, Weybriilge, and Eric Ball, Walton-on-Thames, England, assignors to The British Iron and Steel Research Association, London, England Filed Feb. 19, 1959, Ser. No. 794,324 Claims priority, application Great Britain Feb. 21, 1%8 7 Claims. (Cl. 22-57.2)

This invention relates to continuous casting employing an open-ended mould, into one end of which liquid metal is poured and from the other end of which a solidified or partly solidified casting is withdrawn. This will be referred to hereinafter as continuous casting of the type described.

In the continuous casting of metals, particularly high melting point metals such as iron and steel, in which the liquid metal is poured into the top of a vertical or near vertical water cooled tubular mould, the solidified or partly solidified casting is withdrawn continuously or intermittently from the bottom of the open-ended mould by means of withdrawal rolls or a lowering platform, either of which are positioned below the mould.

In starting the casting process, the lower end of the open mould is sealed by means of a dummy bar, also known asa starting bar, which is gripped by the withdrawal rolls or fixed to the lowering platform below the mould. The first metal cast into the mould is; allowed to solidify in contact with the top of the dummy bar, so forming a junction, which permits the dummy bar to be withdrawn from the mould securely attached to the solidified or partly solidified casting.

As is wellunderstood in the art, the dummy bar may consist of a single length of suitable material, usually of metal, or'a number of shorter lengths connected together either by detachable or non-detachable joints. It is necessary, either during or at the end of the casting operation, to detach the end of the dummy bar from the cast metal. In the present state of the art of continuous casting, in order to prepare the casting machine for the next casting operation, it is necessary for the single bar or series of jointed bars, forming the dummy bar, to be re-inserted into the casting machine in order to re-seal the bottom of the open mould, and so permit the subsequent casting to be withdrawn from the mould by means of the dummy bar and withdrawal mechanism.

In some continuous casting installations it is customary to leave the final length of the casting with its upper end remaining in the mould, while the lower end of the casting is held by the withdrawal mechanism, so that this length of casting serves as the dummy bar for the subsequent casting operation. Prior to the re-commencement of the casting operation, the casting which is left in the machine cools, so that thermal contraction of the casting occurs which causes a space to be formed between the casting and the inner surface of the mould. Owing to small, and usually unavoidable local variations in the solidi ication rate of the casting around its perimeter, internal stresses may occur in the cross-section of the casting. These may result in slight changes in the shape of the cross-section from that originally produced in the mould, and in slight twisting or bending of the casting. Consequently, these phenomena may result in the formation of a non-uniform space between the casting and the mould, which is difiicult to seal adequately by simple means. Furthermore, any slight twisting or bending of the casting which occurs, may produce intimate metallic contact between the casting and mould, so that on resuming the casting operation the mould may be scored or otherwise damaged, so necessitating early replacement of the casting mould.

In a process of continuous casting of the type described, according to one aspect of the present invention, a connection unit is secured to the end of the casting before it leaves the casting mould, the casting is then withdrawn from the mould leaving a part of the connection unit therein as a dummy bar for the subsequent casting. In this way successive castings are jointed together without having to leave the end of the first cast casting in the mould when the next casting commences.

According to another aspect of the invention, continuous casting apparatus for metals comprises an openended mould from which successive castings are progressively withdrawn and a connection unit having a first part arranged to fit slidingly within the mould and to act as a dummy bar, a second part arranged to be cast onto the trailing end of the preceding casting, and a flexible connection coupling together the two parts. A flexible connection is thus formed between successive castings so that a casting is able to deform without severe stress being conveyed to the subsequent casting.

The invention will be more readily understood by way of example from the following description of a connection unit for connecting together the ends of castings in the continuous casting of metals, reference being made to the accompanying drawing which illustrates in section the connection unit located in a mould.

, Referring to the drawing the connection unit consists essentially of an upper part 12 in the form of a dummy bar for the continuous casting mould 13 and a lower part 14 for attachment to the end of the previous casting 15, the two

parts

12, 14 being coupled together by a flexible joint 16 which is substantially rigid to vertical movement and relatively unresistant to rotation or bending.

The lower part 14 consists of a block 17 having the same cross-sectionas the casting 15 and a ,bolt 18 which is secured inthe block 17 by a cotter pin 19. The upper part 12 also has a bolt 21 which protrudes upwardly into a central recess 12a opening to the top of part 12 and which is keyed to the part 12 by a cotter pin 22. The upper part 12 has an annular groove 20 on its outer surface containing a suitable packing material to prevent passage of metal between the mould l3 and the part 12.

The joint 16 is shown as consisting of a pin 23 passing through

openings

24, 25 in hemispherical caps 12b, 14b, attached to

parts

12, 14 respectively and secured at its ends to two

spheres

26, 27 slidably arranged in spherical hollows formed between the

parts

12, 14 and caps 12b, 14b. Round the pin 23 is a spacer 28 having hemispherical end surfaces 29 sliding on caps 12b, 14b.

The connection unit permits a casting to be joined to the last casting 15 without the necessity for leaving the end of casting 15 in the mould. Immediately the casting of casting 15 is completed, the withdrawal of the casting 15 is stopped or substantially slowed down, while the uper or trailing end of the casting 15 still remains in the mould 13. Before the center of the casting has solidified in the mould, the connection unit is inserted through the top of the mould and lowered until the bolt 18 of the lower part 14 enters the liquid pool at the center of the trailing end of the casting, so that, on solidification of the upper end of the casting 15 a strong joint is formed between the top of the casting 15 and the connection unit. The casting and the attached connection unit are then withdrawn to the position shown in the drawing, with the top of the casting 15 below the lower end of the mould 13, and the upper part 12 of the connection unit located in the mould ready to act as the dummy bar for the next casting operation. On the start of the next casting operation, the withdrawal of casting 15 is continued to cause withdrawal of the new casting from the mould.

With a rigid connection between the upper and

lower sections

12 and 14 of the connection unit, any bending or twisting of the casting 15 which may occur prior to the resumption of casting and which is shown for clarity in exaggerated form in the drawing, would result in severe mechanical forces being applied by the connection unit to the mould 13, and possible damage to the mould, so that subsequent withdrawal on the resumption of casting would be rendered difficult. The flexible joint 16 allows limited rotational and lateral movement between

sections

12, 14 in order to accommodate distortion of the casting 15 without severe stress being conveyed to the subsequent casting or endangering the mould.

As casting proceeds sufiiciently in time for the unit to pass the withdrawal rolls, cutting means such as a saw or torch may sever the casting 15 preferably below the level of the block 17 and later in the casting operation above the top level of part 12. By removing the

cotter pins

19, 22

parts

12, 14 are detached from the castings and may be used for subsequent casting operations, while the

bolts

18, 21 firmly attached to the separate pieces of the casting are discarded, and new bolts fitted to the

parts

12, 14 for subsequent casting operations.

We claim:

1. A connection unit for use in a continuous casting process to connect successive castings, said connection unit comprising a first part, a second part and a linkage member engaging said first and second parts, said first and second parts being engaged by said linkage member rotatable and displaceable relative to one another, said first part having in its end face distant from said linkage member a recess and said first part further including a first tubular cavity extending substantially axially into said first part from said recess and a second tubular cavity extending laterally into said first part from one side thereof in partially overlapping relation with said first cavity, whereby a pin may be detachably secured in said first cavity in co-operation with a cotter pin located in said second cavity.

2. A connection unit according to claim 1, comprising a pin located in said first cavity and extending through and beyond said recess, and a cotter pin located in said second cavity to detachably secure the first-mentioned pm.

3. A connection unit according to claim 1, wherein said second part has a first tubular cavity extending substantially axially into the face of the second part distant from said linkage member and a second tubular cavity extending laterally into the second part from one side thereof in partially overlapping relation with said first cavity, whereby a pin may be detachably secured in said first cavity in cooperation with a cotter pin located in said second cavity.

4. A connection unit according to claim 3, comprising a pin located in said first cavity and extending outwardly from the end face of said second part distant from said linkage member, and a cotter pin located in said second cavity to detachably secure the first-mentioned pin.

5. Continuous casting apparatus for metals comprising an open-ended mold from which successive castings are progressively withdrawn and a connection unit having a first part arranged to fit within said mold and to act as a starter head, a second part arranged to be made fast with the trailing end of the preceding casting, and a linkage member pivotally engaging both said first and second parts, said linkage member connecting said first and second parts for independent rotation of the parts relative to one another and lateral displacement of the parts relative to one another in either lateral direction.

6. Continuous casting apparatus according to claim 5, wherein said first and second parts have outwardly projecting members arranged to be set in the ends of castings before solidification thereof to secure said unit thereto upon solidification.

7. Continuous casting apparatus according to claim 6, wherein said projecting members are detachable from said unit.

References Cited in the file of this patent UNITED STATES PATENTS 2,176,990 Crampton Oct. 24, 1939 2,797,482 Zahn July 2, 1957 FOREIGN PATENTS 534,756 Great Britain Nov. 9, 1939 551,842 GreatBritain Mar. 11, 1943 499,748 Italy Nov. 15, 1954 728,4l2 Great Britain Feb. 19, .1953

Claims

1. A CONNECTION UNIT FOR USE IN A CONTINUOUS CASTING PROCESS TO CONNECT SUCCESSIVE CASTINGS, SAID CONNECTION UNIT COMPRISING A FIRST PART, A SECOND PART AND A LINKAGE MEMBER ENGAGING SAID FIRST AND SECOND PARTS, SAID FIRST AND SECOND PARTS BEING ENGAGED BY SAID LINKAGE MEMBER ROTATABLE AND DISPLACEABLE RELATIVE TO ONE ANOTHER, SAID FIRST PART HAVING IN ITS END FACE DISTANT FROM SAID LINKAGE MEMBER A RECESS AND SAID FIRST PART FURTHER INCLUDING A FIRST TUBULAR CAVITY EXTENDING SUBSTANTIALLY AXIALLY INTO SAID FIRST PART FROM SAID RECESS AND A SECOND TUBULAR CAVITY EXTENDING LATERALLY INTO SAID FIRST PART FROM ONE SIDE THEREOF IN PARTIALLY OVERLAPPING RELATION WITH SAID FIRST CAVITY, WHEREBY A PIN MAY BE DETACHABLY SECURED IN SAID FIRST