US2039453A - Bottom-casting hollow ingots - Google Patents

Description

. May 5, 1936. G. RoBsoN BOTTOM CASTING` HOLLOW INGOTS Filed oct( 8, 1954 2 sheets-sheet 1 l f y rm May 5, 1936- G. RoBsoN 2,039,453

BOTTOM CASTING HOLLOW INGOTS Filed Oct. 8, 1954 2 Sheets-Sheet 2 INVENTOR GEORGE ROBSON ATTO NEY Patented May 5, 1936 UNITED STATES oTToM-cssrmc noLLow INGo'rs George Robson, Johannesburg, South Africa, as-

signor to The Union Steel Corporation (of South Africa) Limited, Johannesburg, Union of South Africa, a South' African company Application October 8, 1934, Serial No. 747,451

In South Africa November 8, 1933 is claims. (c1. 22-141) This invention relates to theibottomcasting According to one feature of the invention, I

of hollow ingots, in which the ingot is cast in a mould around a core and/ortubular liner, and has particular reference tothe casting of such ingots for use in manufacturing hollow drill It has been found in practice thatthere. is a tendency for the molten `metal entering the mould to cause scouring of the walls of the latter at its lower end. with the result that the cast ingot in solidifying in the mould binds therein and i's fractured by contraction strains and in consequence a considerable portion of the resulting rolled bar has to be cut oi and discarded as waste.

Also, whereiacentral metal tube containing a metallic core is employed, there is a tendency for the tube to be wholly or partially fused and washed away by the impingement of the molten metal against its surface, and beads of the molten steel can thus flndtheir way into the space between tube and core, thus binding the core in the resulting hollow ingot and making itdiiilcult subsequently to withdraw the core fromV the rolled bar of hollow drill or other steel.

For the purpose of avoiding' damage of the mould walls or core by the molten metal, it has already been proposed to give the mould interior such a cross-section that the distance between.-

the walls of the mould and the core are different at different places and to arrange the inlet opening or openings for the molten metal at the places in the bottom of the mould where such distances are greatest, as for example, by making the mould chamber of square section and lo- :ating the inlet opening or openings on a diagoj nal line in the bottom of the said chamber. With this arrangement, however, the ingots produced are defective because of their irregular shape inevitably results in uneven dendritic growth, which cannot be fully corrected in subsequent rolling, and in consequence of piping troubles, the yield of finished bar from the ingot -is generally not greater than about 75%.

A further drawback which is present in bottom-casting processes proposed vheretofore4 is that provide a' method of bottom-casting hollow ingots, wherein'the casting is carried out ina mould in which the minimum path for the molten metal between the inlet or inlets of the runner- 5 brick and the mould wall, and between such inlet or inlets and the tubular -liner and/or core, lie in different planes so that the metal reaches the said wall and liner and/or core as late as possible after entering the mould consistently withthe size thereof.

According to a further feature of the invention, I provide a method of bottom-casting hollow ingotsA in which the mould is self-centering or" otherwise self-positioning with respect to the core and/or tubular liner (hereinafter simply referred to generally as the core), thereby ensin-ing accuracy in the radial dimensions of the ingot, and avoidance of damage to the mould wall and core. More specifically, I carry out the casting zo in a mould of substantially circular shape so as .to ensure regular dendritic growth, and the molten metal is introduced through an inlet or inlets located in or about the angle between a surface or surfaces extending laterally of' the 25 core and a surface or surfaces extending longitudinally thereof, so that said surfaces intervene between the hot metal initially introduced and the mould walls and core.

In accordance with a further feature of the invention, the casting is carried out in a mould having, at the bottom thereof, a runner-brick with an upstanding projection or projections whereby the length of ingot cast in the mould is determined, the metal connecting the body of the ingot with the runner or feeder of the brick, after solidicatin', constituting a weak spot at which, if the ingot tends to bind in the mould, any resulting fracture can take' place.

My invention also comprises the provision of 4o means for bottom-casting hollow lngots comprising a runner-brick having one or more upstanding projections adjacent to' thecore and an inlet vor inlets for the molten metal located close to the said projections, as far as .possiblebelow the core and inwardly 4oithe mould wall as the size of ingot to be cast permits. The runner-brick may have the projection or projections thereon so shaped andarranged as to facilitate or lensure centering or like positioning of a two-part or like mould relatively to the core, thereby saving time and labour 1n assembly. .More specifically, the. runner-brick may be prc'ividedv on its upper Sul'-` face with a plug-uke projection rounded toni; 55

within the end of a circular mould, andprovided with acentral socket for the reception of the core.

In a preferred embodiment, the runner-brickis provided with an upstanding plug having its' side faces rounded at oppomte sides .to iit within a circular mould andformed with recesses or openings adapted to provide, in conjunction with the wall of the mould, passages or ducts above the holes in the brick through which the molten metal enters themould, said passages or ducts being of substantially greater cross-sectional area than said holes. and serving to reduce the velocity and temperature -.of the entering metal before reaching the core.

The invention will now be described by way of.

example, with reference to the annexed drawings. in whichv Figure 1 is a ,view of the runner-brick in longitudinal section; A

Figure 2 is a plan view of the brick; A Figure3isaperspective view:

Figure 4 is a tic view showing piuglike runner-brick projections of different height; Figure 5 isan outside elevation of the brick on areduced scale with a mould laid thereon, the mould being shown atically.

Figure 6 is a part sectional view of an apparatus embodying the .present invention.

Referring to the drawingsz- The upper surface I of the runner-brick is formed with a plug-like projection 2 having rounded side faces l, l of a diameter corresponding to the inner diameter of the mould with which thebrickistobeused. Arcuaterecesses 5,5 are provided above holes 1, 8 communicating with a feeder passage 9 runninglongitudinally through i the brick. The 5, i are adapted to prov ide in conjunction with the'wall a of the mould (shown calb in Figure 4) passages or ducts of larger cross-sectional area than the holes 1, l. The plug-like projection 2 is formed of refractory material in one piece with the remainder of the brick, and at the top of the projection 2 a recess Il is provided for the accommodation of the lower end of a core and lining tube such as illustrated tically at il lin Figure r y The holes 1,8 are located as close as possible to the adjacent recessed sides of the plug-like pro- -50 ,jection 2, thereby providing a maximum distance between each said-hole and the corresponding adjacent part of the mould wall. adapted to rest on the brick, while simultaneously preserving a suilicient distance between each said hole and the top of the projection 2, on which the core and tube rest f By means the separations possible in any given size of mould between the entering molten steel, mould wall and central tube are lengthened 60 and scouring of the mould and fusion and collapse of tubes are eliminated or reduced. In practicelhave found that withtheuse o'f the runnerbrick described it is possible to treble the life of the moulds and no trouble is experienced through fast cores.

The runner-brick also enables a round mould tobe successfully employed and due to unito-i and rapid cooling, regular radial dendritic gr is ensured. I have found from experience u at by the use of the runner-brick described, in co junction with a mould as set forth in my copending patent application Serial No. 747,452', led October 8, 1934, it is possible to-secure a yield of finished metal of 6'1 ik per cent. The com.- hination of the saidlmould and brick also gives the use of an improved type of mould with solid top portions, as described in our aforesaid copending patent application.

As illustrated .diagrammatically in Figure 4,

bricks having plug-like projections 1a, 1b, 1c of.

different height may be employed in conjunction with the same mould so that the length of ingot Icast therein may be varied, and thus .desired iinished lengths of bars of the same or dierent section obtained while using the same mould. For

. example, as 'shown in Fig. 6, bricks having high projections may be placed under the moulds nearest the trumpet I2 through which the hot steel or metal is fed, while bricks with lower projections may be inserted under the moulds further away from the trumpet. The higher projections protect the nearest ring of ingots from the risk of collapsed tubes and fast cores. Similarly. by.

setting up one plate of moulds with bricks having tall projections and another plate with brickshaving lower projections, it is possible to cast two plates from the same ladle of steel successfully.

I claimz- 1. Means for bottom-casting hollow ingots, comprising a runner-brick having holes in the upper surface thereof for passage of molten metal, a mold supported on the runner-brick. and y an upstanding projection provided upon ,the runner-brick, said projection having its side faces so shaped as to lit within the mold to Afacilitate centering of the mold on the runner-brick and so as to form with the wall of the mold ducts above the holes in the runner-brick through which the molten metal enters the mold.

2. Means for bottom-casting hollow ingots. comprising a runner-brick having holes in the upper surface thereof for passage of molten metal, a mold supported on the runner-brick, and an upstanding projection provided up'on the runnerbrick, said projection having its side faces so shaped as to fit within the mold to facilitate centering of the mold on the rimner-brick and' so as to -form with the wall of the mold ductsabove the holes in the runner-brick through y which the molten metal enters the mold, the ducts being of greater cross-sectional area than the holes.

3; Means for 4bottom-casting hollow ingots, comprising a runner-brick having holes in the upper surface thereof for passage of molten metal, a mold supported on the runner-brick, and an upstanding projection provided upon the runner-brick, said projection having its side faces so shaped as to fit within the mold to facilitate centering of the mold on the runner-brick andi so as to form with the wall of the mold ducts" ab ove the holes in the runner-brick through which the molten metal enters the mold, and said projection being formed of the same'material as the body of the runner-brick..

4. Means for bottom-casting hollow ingots,

comprising arunner-brick having holes in the '.ffnpper :surface thereof for passage of molten:

. and an upstanding projection provided upon the runner-brick, the projection having its side faces soshaped as to fit within the mold to facilitate centering of the mold on the runner-brick and so as to form with the wall of the mold ducts above the holes in the runner-brick through which the molten metal enters the mold, the ducts being of greater cross-sectional area than the holes, and said projection being formed of the same material as the body of the runnerbrick.

5. Means for bottom-casting hollow ingots, comprising a runner-brick having holes Ain the upper surface thereof for passage of molten metal, a mold supported on the runner-brick, and an upstanding projection having its side faces so shaped as to iit within the mold to facilitate centering of the mold on the runner-brick and so as to form with the wall of the mold ducts above the holes in the runner-brick through which the molten metal enters the mold, and said projection being formed of the same material as the body of the runner-brick and integrally therewith. v

6. Means for bottom-casting hollow ingots, comprising a runner-brick having holes in the upper surface thereof for passage of molten metal, a mold supported on the runner-brick,V`

and an upstanding projection provided upon the runner-brick, the projection having its side faces so shaped as to iit within the mold to facilitate centering of the mold on the runner-brick and so as to form with the wall of the mold ducts above the holes in the runner-brick through which the molten metal enters the mold, the ducts being of greater cross-sectional area than the holes, and sai'd projection being formed of the same material as the body of the runner-brick, andA integrallyv therewith.

'7. Means for bottom-casting comprising `a runner-brick having holes in the upper surface thereof for. passage of molten metal, a mold' supported on the runner-brick, and an upstanding projection provided upon the runner-brick, the projection having its side faces so shaped as to fit within the mold to facilitate Cil comprising a pouring' trumpet, a plurality of run-i ner-bricks having ducts extending longitudinally therethrough, said runner-bricks being successively spaced from said trumpet and having their ducts serially connected to said trumpet, each of said runner-bricks having openings extending through the upper surface thereof, and a moldcentering projection on the upper surface of each brick, the projections on the bricks nearest the I I hollow ingots,

trumpet being higher than the projections on the bricks farther away from the trumpet.

9. An apparatus ofthe character described, comprising -a pouring trumpet, a plurality of runner-bricks having ducts extending longitudinally therethrough, said runner-bricks being successively spaced from said trumpet and having their ducts serially connected to said trumpet, each of said runner-bricks having openings extending through the upper surface thereof, mold-fv 10. Means for bottom-casting Ihollow ingots comprising a runner-brick provided with an upstanding projection having its side faces rounded at opposite sides to iit withina circular mould and formed with openings adapted to provide, in conjunction with the wall of the mould, ducts above the holes in the brick through which the molten metal enters the mould, said ducts being y.

of substantially greater cross-sectional area than said holes.

11. Means forbottom-casting hollow ingots comprising a runner-brick provided with an upstanding projection having its side faces rounded at opposite sides to fit within a circular mould and formed with openings adapted to provide, in conjunction with the wall of the mould, ducts above the holes in the brick through which the molten metal enters the mould, said ducts being of substantially greater cross-sectional area than said holes and sa'id projection being formed of the same material as the body of the runnerbrick.

12. Means for bottom-casting hollow ingots comprising a runner-brick provided with an upstanding projection having its side faces rounded at opposite sides to t within a circular mould and formed with openings adapted to provide, in conjunction with the wall of the mould, ducts above the holes in the brick through which the molten metal enters the mould, said ducts being of substantially greater cross-sectional area than said holes, the projection being formed integrally 'with the body of the runner-brick.

13. Means for bottom-casting hollow lingots comprising a runner-brickv provided withan upstandingprojection having its side faces rounded I at opposite sides to t within a circular mould and formed with openings adapted to provide, in

conjunction with the-wall of the mould; ducts above the holes in the brick through which the molten metal enters the mould, said ducts being of substantially greater cross-sectional area than said holes and said Yprojection'being formed of the same material as the body of the runner-brick vand integrally therewith.

GEORGE ROBSON.

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