US3455374A

US3455374A - Feed for continuous casting apparatus

Info

Publication number: US3455374A
Application number: US647679A
Authority: US
Inventors: Kurt R Behrsin
Original assignee: Phelps Dodge Copper Products Corp
Current assignee: Phelps Dodge Copper Products Corp
Priority date: 1967-06-21
Filing date: 1967-06-21
Publication date: 1969-07-15
Anticipated expiration: 1986-07-15
Also published as: DK117318B; DE1758490B1; NL6808823A; AT285846B; SE339535B; BE716740A; GB1180338A; FR1572660A

Description

July 15, 1969 Filed June 21, 1967 K. R. BEHRSIN FEED FOR CONTINUOUS CASTING APPARATUS 2 Sheets-Sheet 1 FIGS July 15, 1969 K. R. BEHRSIN FEED FOR CONTINUOUS CASTING APPARATUS 2 Sheets-Sheet 2 Filed June 21, 1967 INVENTOR. KURT R- BEHPS/N United States Patent US. Cl. 164-276 6 Claims ABSTRACT OF THE DISCLOSURE A generally horizontal annular trough forming a circular mold cavity is rotated about a generally vertical axis to transfer molten metal through a solidifying zone and thence through .a station where the solidified metal is continuously removed from the trough. The molten metal is fed to the mold cavity from a supply means by way of a pouring cup having a main chamber, a discharge spout and an overflow weir over which the chamber communicates with the spout, the latter having a discharge end leading into the mold cavity in the direction of its rotation. Shoe means secured to the pouring cup have a sliding fit in the mold for floatingly supporting the cup, and an element coacts with the shoe means to restrain,the cup against rotation with the mold. Preferably, the shoe means 'form a dam to limit reverse flow of the molten metal delivered to the mold, and a lower surface of the shoe means is slanted so as to raise the pouring cup when engaged by solidified metal not discharged at the removing station. The overflow weir is preferably located at such an elevation above the mold that the molten metal at the discharge end of the spout is travelling at approximately the same linear speed as the mold.

THE DISCLOSURE This invention relates to casting apparatus of the type in which the molten metal is continuously fed from a supply station into a mold consisting essentially of a circular trough rotating about a generally vertical axis of the circle, whereby the metal solidifies as it is carried by the rotating trough to a discharge station which removes the metal continuously as a rod, or the like.

An apparatus of the above-mentioned type alfords numerous advantages, especially in the improved form disclosed in US. Patent No. 3,284,859, granted Nov. 15, 1966. However, the quality of the cast product from such apparatus is dependent to a considerable extent upon the means for feeding the molten metal into the circular mold. More particularly, the quality is improved if the feeding means operate to provide a uniform feed and to avoid undue turbulence of molten metal in the mold. Amongthe conditions which have largely defeated attainment of these objectives are unavoidable variations in the rate at which the molten metal is delivered from the launder or other source supplying the feeding means, and changes in the diameter or position of the circular mold due to thermal expansion and contraction.

The principal object of the present invention is to provide apparatus of the type described having improved means by which the above-noted objectives are attained in feeding the molten metal to the circular mold.

According to the invention, the molten metal is fed to the circular mold from a supply source by way of a pouring cup having a main chamber, a discharge spout and a weir over which the chamber communicates with the spout, the latter having a discharge end leading into the mold in the direction of its rotation. The pouring cup is floatingly supported by shoe means seated in the mold with a sliding fit, an element being provided for restrain- 3,455,374 Patented July 15, 1969 ing the cup against rotation with the mold while allowing free movements of the cup vertically and laterally. The overflow weir is preferably located at a level above the mold such that the molten metal flows through the discharge end of the spout at a linear speed approximately equal to the linear speed of the mold. Also, the shoe means are preferably provided with a slanted lower surface forming with the bottom of the trough mold a wedge-shaped recess tapering in the direction of rotation, whereby any solidified particles remaining in the mold will lift the pouring cup by a camming action on the slanted surface, rather than cause breakage.

The invention is described in further detail hereinafter with reference to the accompanying drawings, in which:

FIG. 1 is a plan view of a preferred form of the new apparatus;

FIG. 2 is a side elevational view of part of the apparatus illustrated in FIG. 1, showing the feeding means for the molten metal; and

FIG. 3 is a sectional view on line 3-3 in FIG. 2.

Referring to FIG. 1, the continuous casting apparatus there shown comprises a stationary vertical post or axle 20 extending through a hub 21 having a close rotating fit on the axle. Hub 21 is adapted to be rotated on the axle at constant speed by a motor 22 connected through a variable speed transmission 23 and shaft 24 to a bevel gear 25 meshing with a large bevel. gear 26, the latter being secured to hub 21.

The hub 21 has rotating spokes 28 secured at their outer ends, as by welding, to an annular trough 29 having a circular mold cavity 29a which is open at the top. The ring-shaped trough 29 is supported on horizontal rollers 30 spaced around the vertical axle 20 and mounted on suitable stationary supports (not shown).

The motor 22 operates through hub 21 and spokes 28 to rotate the annular trough 29 about the vertical axle 20 as an axis. For simplicity and to avoid duplication,

only some of the rollers 30 are illustrated, it being understood that they are provided in suflicient number to support the circular trough 29 in a horizontal position when it is rotated and loaded with the casting metal.

The molten metal is fed continuously into the rotating mold cavity 29a by a feeding means 32 to be described in greater detail presently. The mold rotates counterclockwise as viewed in FIG. 1, thereby carrying the metal from the feeding means 32 through an overlying gasapplying station 33 and through underlying and overlying cooling stations (not shown). Continued rotation of the mold then carries the solidified metal to a cast metal discharge station 34, where it is continuously discharged from the mold. As the mold continues to rotate from the discharge station 34, it may pass through stations (not shown) for preheating and dressing the mold before it reaches the feeding means 32. The details of the gas-applying station 33, the cooling stations, the discharge station 34 and the preheating and dressing stations may be as disclosed in the aforementioned Patent No. 3,284,859.

Referring now to FIGS. 2 and 3, the feeding means 32 comprise a pouring cup 36 which is preferably lined with a refractory material. The cup 36 has a main chamber 37 open at the top for receiving molten metal from a launder 38 or other source. The pouring cup also has an overflow weir 39 over which the main chamber 37 communicates with a discharge spout 40 of the cup. The spout 40 has an entrance end 40a which receives the molten metal from the overflow weir 39' by way of a subchamber 37a of the cup. From its entrance end 40a, the spout extends downwardly and forwardly in the direction of rotation of the underlying mold cavity 29a, the spout terminating outside the body of the cup 36 in a discharge end 40b. The latter is received in the upper part of discharge end has a width substantially equal to the width of the mold cavity 29a, as best seen in FIG. 3.

The pouring cup 36 is supported by means comprising a pair of graphite shoes 42 and 43 seated on the bottom of the mold cavity 29a and each having a sliding fit in this cavtiy. The shoes are secured to the bottom of cup 36, by

means including bolts

42a and 43a, respectively, for connecting the shoes to depending flanges 36a of the cup. The front shoe 42 is located adjacent the discharge end 40b of the spout and has a close sliding fit in the mold cavity 29a so as to form a dam for preventing reverse flow of the molten metal entering the cavity from the spout 40. The shoe means 42-43 thus fioatingly support the pouring cup 36, including its spout 40, to allow free movements thereof vertically and laterally as the trough 29 rotates. An element 45, serves to restrain the cup 36 against rotation with the trough 29. This element, as shown, is a fixed stop engageable by the front end of cup 36, thereby holding the cup against movement by rotation of the trough while allowing free movements of the cup vertically and laterally.

The shoes 42 and 43 have slanting lower surfaces 42b and 43b, respectively, each forming with the bottom of the mold cavity a wedge-shaped recess tapering in the direction of rotation of the trough 29. The slanting lower surface 42b has the effect of increasing the unit pressure exerted by the front of shoe 42 against the bottom of mold cavity 29a, thereby enhancing the action of this front shoe as a dam. Also, in the event that solidified metal particles remain in the mold cavity after discharge of the casting at station 34 (FIG. 1), such particles will exert a camming action on the slanting surfaces 43b and 4217 so as to raise the pouring cup, thus avoiding breakage which might otherwise occur.

As shown in FIG. 2, the pouring cup 36 is located closely adjacent the gas-applying station 33, which comprises a hood 50 held stationary by a suitable support 51 (FIG. 1). The interior of hood 50 is charged with a nonoxidizing gas, such as nitrogen or argon, so that the molten metal discharged from spout 40 is immediately subjected at its upper surface to the non-oxidizing atmosphere.

By virtue of the overflow weir 39 leading from the main chamber or reservoir 37 of the pouring cup, the kinetic energy of the metal stream delivered into the cup from the supply source 38 is largely absorbed, and the molten metal flows over the weir in a smooth, nonturbulent stream for delivery into the casting mold by way of spout 40. For best results, the weir 39 should be located above the mold cavity 29a at a level such that the linear speed of the metal at the discharge end 40b of the spout is about equal to the linear speed of the rotating mold. In this way, and because the throughflow width of spout 40 is about equal to the width of mold cavity 29a (FIG. 3), the molten metal will undergo a minimum of turbulence when it is received by the mold cavity.

It will also be noted that the pouring cup 36 is mounted independently of the bulky supply system 38 and, being of small capacity and therefore correspondingly light in weight, can follow deviations in the level and diameter of the circular mold cavity 29a accurately and promptly. Accordingly, these deviations do not affect the position of the pouring cup relative to the mold cavity.

Preferably, the hood 50 of the gas-applying station 33 contains nozzle means (not shown) for concentrating a stream of the inert gas upon the upper surface of the molten metal being cooled in the mold 29a, thus forming by convection cooling a solid metal skin at the upper surface prior to complete solidification of the metal in the mold, whereby the casting is discharged with a flat upper surface so that it is suitable for hot rolling. This feature is no part of the present invention but is the subject of an application of Douglas C. Yearly filed concurrently here with.

I claim:

1. In combination with a generally horizontal annular trough forming a circular mold open at the top and adapted to receive molten metal, means for supplying molten metal for continuous casting in said mold, means for rotating the trough about a generally vertical axis 7 in one direction relative to said supply means, and means adjacent the trough for continuously removing solidified metal from the mold as the trough is rotated, a pouring cup having a main chamber for receiving molten metal from said supply means, the cup having a discharge spout and also having an overflow weir over which said chamber communicates with the spout, said spout having a discharge end leading into the mold in said one direction to deliver molten metal from the supply means by way of said chamber and weir, shoe means secured to the cup and seated in said mold with a sliding fit for fioatingly supporting the cup, and an element cooperating with said shoe means to restrain the cup against rotation with the trough in said one direction.

2. The combination according to claim 1, in which said discharge end of the spout is located in the mold and has a throughflow area with a width substantially equal to the width of the mold.

3. The combination according to claim 1 in which said shoe means form a dam adjaecnt said discharge end of the spout and operable to limit flow of the metal in the mold in the direction opposite to said direction of rotation.

4. The combination according to claim 1, in which said shoe means include a shoe having a slanting lower surface forming with the bottom of the mold a wedgeshaped recess tapering in said one direction and adapted to receive unremoved metal carried by the mold from said removing means, whereby said unremoved metal is operable on said lower surface to raise the pouring cup relative to the mold.

5. The combination according to claim 1, in which said shoe means include a shoe having a slanting lower surface forming with the bottom of the mold a wedge-shaped recess tapering in said one direction and adapted to receive unremoved metal carried by the mold from said removing means, whereby said unremoved metal is operable on said lower surface to raise the pouring cup relative to the mold, said shoe means also including a second shoe adjacent said discharge end of the spout and operable to limit flow of the metal in the mold in the direction opposite to said one direction, said second shoe having a lower surface similar to said slanting lower surface of the first shoe.

6. Apparatus according to claim 1, in which the overflow weir is located above the mold at a level such that the molten metal flows through said discharge end of the spout at a linear speed approximating that of the mold.

References Cited UNITED STATES PATENTS 6/1955 Properzi 164283 X 11/1966 Conlon et al. 164283 X US. Cl. X.R. 164-28l