GB2129344A

GB2129344A - Direct chill casting

Info

Publication number: GB2129344A
Application number: GB08304236A
Authority: GB
Inventors: Frank E Wagstaff; William G Wagstaff; Richard J Collins
Original assignee: Wagstaff Engineering Inc
Current assignee: Wagstaff Engineering Inc
Priority date: 1982-10-20
Filing date: 1983-02-16
Publication date: 1984-05-16
Also published as: CA1238763A; JPS61262449A; FR2534832A1; AU1413783A; GB8304236D0; SE8300849L; CH675086A5; NO830858L; NO160246C; FR2534832B1; JPS5992147A; SE8300849D0; SE459325B; DE3338185C2; GB2129344B; DE3338185A1; JPS6147622B2; NO160246B; AU567872B2

Description

1 GB 2 129 344 A 1

SPECIFICATION Direct chill metal casting apparatus and technique

This invention relates to the direct chill casting of metals such as aluminum.

When casting a metal in this fashion, a mass of the molten metal is introduced into the top of an open bottomed mold cavity having a support telescoped therein, the molten metal mass is chilled, and the mold and support are reciprocated in relation to one another axially of the cavity to form the chilled mass into an elongated body of the metal. Normally, the molten metal is introduced into the top of the cavity through an opening having a smaller diameter than the peripheral wall of the cavity, and the molten metal splays into a metallic mass the meniscus of which tends to contact the peripheral wall of the cavity in the plane of maximum divergence of the metal.

Moreover, the metallic mass normally assumes a divergent-convergent cross-sectional outline, the intermediate continuum of which between the planes of maximum divergence and minimum convergence thereof, has a peripheral outline corresponding generally to the peripheral outline of the cavity at the wall thereof. Meanwhile, there is a pocket of relatively metal-free space formed between the meniscus of the metal and the top corner of the cavity at the overhang thereof about the opening.

In USP 4,157,728, a stream of pressurized air is delivered to the top of this pocket, to pressurize the same, and the mold operator is instructed to use the pressurization of the pocket itself, internally of the cavity, as a means for generating a sleeve-like annulus of gas which, given certain idealized conditions in the pocket, will tend to flow downwardly about the metallic mass at the periphery of the cavity. According to the invention, however, a stream of pressurized gas is 105 delivered to a point outside of the cavity, the gas is discharged into the cavity at a point on the periphery thereof, and means are interposed between the point of delivery and the point of discharge, externally of the cavity, to convert the 110 stream of gas into an annulus of fluid that extends about the metallic mass at the periphery of the cavity. In this way, it is now possible for the mold designer to build in the conditions for generating and maintaining the annulus and they no longer 115 must be left to the skill of the mold operator.

Generally, the annulus is generated below the top of the pocket so that the fluid tends to flow upward into the same. However, the annulus is also normally generated above the bottom of the 120 cavity, so that the fluid also tends to flow downwardly as well, that is, both upward and downward of the cavity, axially thereof.

In many of the presently preferred embodiments of the invention, the gas is 125 discharged into the cavity at a point adjacent the plane of maximum divergence of the metallic mass. In certain of these embodiments, the gas is discharged from the peripheral wall of the cavity at a point disposed opposite the peripheral outline of the intermediate continuum of the metallic mass. In some embodiments, moreover, the gas is discharged at points on the peripheral wall of the cavity circumposed about the entire perimeter of the intermediate continuum of the metallic mass, and preferably at points on the wall arrayed over the entire height of the intermediate continuum.

In one group of the presently preferred embodiments, the gas is relatively depressurized and/or diffused as it flows between the point of delivery and the point of discharge. For example, in certain of these embodiments, a solid but gasimpregnable structural medium is interposed between the point of delivery and the point of discharge that relatively depressurizes and diffuses the gas and discharges it into the cavity at a point adjacent the plane of maximum divergence of the metallic mass. In some of them, the gas impregnable medium is positioned at the peripheral wall of the cavity and the gas is delivered to the same so that it discharges at a point opposite the peripheral outline of the intermediate continuum of the metallic mass. In many, moreover, the gas- impregnable medium is extended around the entire perimeter of the cavity and the gas is delivered to the same so that it discharges at points circumposed about the entire perimeter of the intermediate continuum of the metallic mass. In many of the latter, moreover, the medium is elongated axially of the cavity and the gas is delivered to the same so that it discharges at points arrayed over the entire height of the continuum.

Normally, a lubricating oil is delivered to the pocket of the cavity. In some of the presently preferred embodiments of the invention, the oil is discharged into the cavity through the overhang at the top of the pocket. Moreover, in certain of them, a portion of the oil vapor is trapped in the top of the corner of the pocket during the casting operation.

In one group of the presently preferred embodiments of the invention wherein oil is delivered to the pocket, a gas-impregnable ring is positioned at the top of the cavity to define the corner of the pocket at an annular step therein which is co-planar with the overhang about the top opening of the cavity. The ring is elongated axially of the cavity so that the upper and lower end portions thereof are disposed opposite the pocket and the peripheral outline of the intermediate continuum of the metallic mass, respectively. And the oil and gas are delivered to the ring so that the gas discharges from the same at inner peripheral points on the ring adjacent the continuum, and the oil discharges into the pocket at points thereabove, including at points on the step.

In one special group of embodiments, a stream of pressurized lubricating oil is delivered to a point outside the cavity, suspended in a highly heat vaporizable liquid carrier, the oil is discharged into the pocket of the cavity at a point on the periphery thereof, and means are interposed 2 GB 2 129 344 A 2 between the point of delivery and the point of discharge, externally of the cavity, to convert the carrier into an annulus of vapor that extends about the metallic mass at the periphery of the cavity.

The present invention also relates to a metal casting device of the aforementioned type wherein a mass of molten metal is introduced into the top of an open-bottomed mold cavity having a support telescoped therein, the molten metal mass is chilled, and the mold and support are reciprocated in relation to one another axially of the cavity to form the chilled mass into an elongated body of the metal. According to the invention, the device further comprises means for delivering a stream of pressurized gas to a point outside of the cavity, means for discharging the gas into the cavity at a point on the periphery thereof, and means interposed between the point of delivery and the point of discharge, externally of the cavity, to convert the stream of gas into an annulus of fluid that extends about the metallic mass at the periphery of the cavity.

As indicated earlier, in certain devices of the foregoing type, the molten metal is introduced into the top of the cavity through an opening having a smaller diameter than the peripheral wall of the cavity so that the molten metal splays into a metallic mass the meniscus of which tends to contact the peripheral wall of the cavity in the plane of maximum divergence of the metal, there being a pocket of relatively metal-free space formed between the meniscus of the metal and the top corner of the cavity at the overhang thereof about the opening. According to the invention, where this is the case, the gas discharge means and the external conversion means are preferably jointly operable to generate the annulus below the top of the pocket, but above the bottom of the cavity. Moreover, the gas 105 discharge means are often operable to discharge the gas into the cavity at a point adjacent the plane of maximum divergence of the metallic mass. Furthermore, where the metallic mass assumes a divergent-convergent cross-sectional 110 outline between the top and bottom of the cavity, the intermediate continuum of which between the planes of maximum divergence and minimum convergence, has a peripheral outline corresponding generally to the peripheral outline 115 of the cavity at the wall thereof, the gas discharge means are often operable to discharge the gas from the wall of the cavity at a point disposed opposite the peripheral outline of the intermediate continuum of the metallic mass. In fact, in many embodiments, the gas discharge means are operable to discharge the gas at points on the wall of the cavity circumposed about the entire perimeter of the intermediate continuum of the metallic mass, and preferably at points on the wall 125 arrayed over the entire height of the intermediate continuum.

Furthermore, in one group of the presently preferred embodiments, the external conversion means are operable to relatively depressurize and/or diffuse the gas as it flows between the point of delivery and the point of discharge. For example, in certain embodiments, a solid but gasimpregnable medium is interposed between the point of delivery and the point of discharge, which is operable to relatively depressurize and diffuse the gas and discharge it into the cavity at a point adjacent the plane of maximum divergence of the metallic mass. In some of these embodiments, the gas-impregnable medium is disposed at the peripheral wall of the cavity and the gas delivery means are operable to deliver the gas to the same so that it discharges at a point opposite the peripheral outline of the intermediate continuum of the metallic mass. In many, moreover, the gasimpregnable medium extends around the entire perimeter of the cavity and the gas delivery means are operable to deliver the gas to the same so that it discharges at points circumposed about the entire perimeter of the intermediate continuum of the mass. Furthermore, in many of the latter, the medium is elongated axially of the cavity and the gas delivery means are operable to deliver the gas to the same so that it discharges at points arrayed over the entire height of the continuum.

The presently preferred embodiments of the invention often further comprise means for delivering a lubricating oil to the pocket of the cavity. In some embodiments, the oil delivery means are operable to discharge the oil into the cavity through the overhang at the top of the pocket. In certain of them, moreover, there are means for trapping a portion of the oil vapor in the top of the corner of the pocket during the casting operation.

In one group of the presently preferred embodiments, a gas-impregnable ring of graphite or the like is positioned at the top of the cavity and the ring has an annular step therein which is co-planar with the overhang about the top opening of the cavity and defines the corner of the pocket. The ring is also elongated axially of the cavity so that the upper and lower end portions thereof are disposed opposite the pocket and the peripheral outline of the intermediate continuum of the metallic mass, respectively. The respective oil and gas delivery means are operable to deliver the same to the ring so that the gas discharges at inner peripheral points on the ring adjacent the continuum, and the oil discharges into thd pocket at points thereabove, including at points on the step.

Often, the invention further comprises a support or stool for telescoping into a metal casting device such as that described. According to the invention, the stool comprises a pair of operatively coaxially disposed cap and base members which are slidably engageable with one another at mutually opposing surfaces thereon and equipped with cooperatively male and female catch means on the surfaces thereof. The female catch means have a laterally offset groove therein on the axis of the members, and the male catch means are insertable in the female means when 1 3 GB 2 129 344 A 3 the members are engaged with one another at the surfaces eccentrically of the axis, and engageable in the groove when the members are laterally displaced in relation to one another to a point at which they assume concentricity with the axis. 70 The stool also comprises first and second latch means which are shiftable laterally and axially of the axis respectively, to latch and unlatch the members against relative axial and lateral displacement, respectively, when the members are engaged with one another at the surfaces and relatively laterally displaced to and from said point, and maintained at said point, respectively.

However, the second latch means and the cap member are engageable with one another in the latched condition of the cap member to allow for limited lateral displacement of the same in self aligning with the device.

The present application is a continuation in part of our co-pending Application Serial No.

258,520 filed April, 29, 1981 and entitled Molded Device And Method Of Forming The Same. Accordingly, the invention also concerns an improved billet casting mold for a bottom loaded coolant box casting device of the type disclosed therein wherein the coolant box has a registering top and bottom openings in the chamber thereof, the top opening of which has a shoulder thereabout and the bottom opening of which opens into the bottom of the box and has a 95 greater diameter than the top opening of the chamber. According to the invention, the billet casting mold comprises a pair of cooperatively engageable top and bottom rings, the top ring of which is adapted to be inserted upwardly into the chamber through the bottom opening thereof and abutted against the shoulder about the top opening. The top ring has apertures in the body thereof which are adapted to open into the bottom of the chamber when the ring is inserted 105 into the chamber and abutted against the shoulder. It also has an arcuate step thereon that overhangs the apertures and is circumposed about the inner periphery of the top ring at a level adapted for discharging a curtain of coolent liquid 110 onto the emerging billet from the chamber. The bottom ring is adapted to telescope within the top ring and to co-operate with the step in forming an annular passage for the coolant therebetween which communicates with the apertures in the 115 body of the top ring and extends upwardly therefrom to a point at which it then curves reentrantly downwardly to the inner periphery of the top ring for discharge of the curtain. The bottom ring also has a flange thereon which is engageable with the bottom of the box to -locate one ring within the other when the passage is formed.

The invention also relates to the combination of a bottom loaded coolant box casting device of 125 the aforementioned type, and an apertured hot top which is superposed thereabove. According to the invention, the aperture of the hot top registers with the top opening of the box but is smaller in diameter than the same, and there is a flanged 130 insulative refractory scupper telescoped in the aperture, the flange of which is disposed below the overhang of the aperture in the top opening of the box.

These features will be better understood by reference to the accompanying drawings which illustrate several embodiments of the invention when it is employed in a multi-site, direct chill billet casting apparatus incorporating both the aforementioned combination and the improved billet casting mold.

In the drawings, Figure 1 is a part vertical cross-sectional view of one casting site when the casting operation is conducted with a gasimpregnable ring of graphite or the like at the top of the mold cavity therein; Figure 2 is a part cross-sectional upward plan view of the site along the line 2-2 of Figure 3; Figure 3 is a part cross-sectional view of the site along the line 3-3 of Figure 2; Figure 4 is a partially exploded, part cross sectional view of the site; Figure 5 is an enlarged part cross-sectional view of the site along the line 5-5 of Figure 2; Figure 6 is a more greatly enlarged part cross sectional view of the site at the gas-impregnable ring thereof; Figure 7 is a similar view of an alternative form of ring; Figure 8 is another such view of still another form of ring; Figure 9 is a fourth version of the ring; Figure 10 is a fifth version of the same; Figure 11 is a part-perspective view of the fifth version; Figure 12 is an exploded top perspective view of the support or stool used at the site; Figure 13 is a bottom perspective view of the stool cap; Figure 14 is a vertical cross-sectional view of the stool in the latched condition of the cap; Figure 15 is a similar view of the stool after the cap has been unlatched; and Figure 16 is a third such view of the stool after the cap has been removed.

Referring to the drawings, it will be seen that as in the co-pending Application, the billet casting apparatus comprises a multiple site casting device 2 of the coolant box type, a hot top 4 for feeding the respective casting sites 6 of the device, and an assembly of telescoping stools 8 for supporting the elongated billets 10 progressively formed at the sites. The casting device comprises a large widely dimensioned box 12 having a correspondingly sized chamber 14 therein for circulating a liquid coolant such as water to the respective casting sites. The box 12 also has equally sized openings 16 in the bottom 18 thereof, corresponding in number and location to the castings sites, and equally sized openings 20 in the top 22 thereof which are vertically aligned with but smaller than the bottom openings 16 of the box at the respective sites. The top openings 20 each have an annular rabbet 40 (Figure 3) about the inner peripheral edge 4 GB 2 129 344 A 4 thereof, the vertical wall of which is rabbeted in turn at the bottom thereof to form an annular shoulder or step 42 thereon. The bottom openings 16 each have a set of threaded holes 24 (Figure 4) spaced about the perimeter thereof for an attachment purpose to be explained, and an additional set of threaded holes 26 (Figure 5) more radially offset therefrom, which are employed in plumbing air and lubricating oil to the site, as shall also be explained.

The hot top 4 includes a molten metal distribution pan 32 which has a set of apertures 34 therein that are adapted to hold an equal number of insulative refractory scruppers 28 at the respective casting sites. The apertures register 80 with but are smaller in diameter than the corresponding top openings 20 of the box, and are sized to slideably receive the scuppers. Each scupper has a tapered bore 36 and a cylindrical outer configuration which is flanged at an intermediate level thereof. The flanges 38 are sized to fit within the openings 20 of the box.

When the pan 32 is in place, the scuppers are mounted in the same way by inserting them upwardly through the respective bottom openings 16 of the box and then into the corresponding top openings 20 thereof. As they pass through the openings 20, they engage in the apertures 34 of the pan. Meanwhile, the flanges 38 on the outside of the scuppers telescope into the openings, 95 leaving only the bottom portions 28' of the scuppers depending within the chamber.

In addition to the box, the casting device also comprises a set of annular billet casting molds 30 which are likewise mounted at the respective sites by inserting them upwardly through the bottom openings 16 of the box. However, in this case, the molds are abutted against the top 22 of the box and engaged between the depending portions 28' of the scuppers and the rabbeting 40, 42 about the openings 20 of the box. When so engaged, they seal with the top of the box, as shall be explained, and trap the flanges 38 of the scuppers in the openings 20 of the box. They also engage with the bottom of the box, and seal to it as well, as shall be explained. Ultimately, capscrews 44 are employed to secure the molds in place, using the threaded holes 24 about the respective openings 16.

Each billet casting mold 30 (Figure 4) comprises a deep cylindrically inner surfaced metal casting ring 46, a more shallow, but similarly inner surfaced graphite feed ring 48 of slightly smaller inner diameter, a relatively flat, small diameter, cylindrically inner surfaced top ring 50 of insulative refractory material, a retainer ring 52 for use between the rings 46 and 50, and a widely flanged attachment ring 54 that cooperatively inserts within the casting ring 46 to define a coolant flow passage 56 therebetween (Figure 3), as shall be explained. The casting ring has a wide, deeply inset, inner peripheral rabbet 58 at the top thereof, and the bottom of the same has a narrow and more shallow rabbet 60 at the inner peripheral edge thereof. The vertical wall of the wider rabbet 58 is threaded at the top thereof, and after the feed ring 48 and the top ring 50 are seated in the respective rabbets 60, 58 in that order, the retainer ring 52 is threaded into an outer peripheral rabbet 62 in the upper surface of the top ring 50, to clamp the assembly in place. Additionally, there is a narrower outer peripheral rabbet 64 at the top of the casting ring, an annular groove 66 acutely angled into the corner of the rabbet, and an annular dovetail-crosssectioned groove 68 in the top of the ring just inside of the rabbet 64. A pair of elastomeric 0rings 69 and 70 is seated in the respective grooves, to form a sea[ between the top of the casting ring and the abutting surface of the rabbet 40 in the top of the box, on one hand, and the corner of the rabbet 64 of the ring 46 and the shoulder or step 42 of the box on the other. Meanwhile, the smaller diameter top ring 50 is slideably engaged about the scupper and together with the bottom of the scupper, forms a wide overhang 71 directly above the feed ring. The top ring and retainer ring normally do not abut the top of the box, however.

go At the bottom, the casting ring 46 has a high inner peripheral rabbet 72, the vertical wall 74 of which is somewhat radially enlarged at levels above that corresponding to the bottom of the chamber 14 when the mold is inserted therein. Moreover, the top of the step 74 of the rabbet is circumposed about the ring at a level adapted for discharging a curtain of coolant liquid onto the emerging billet from the chamber. The top also has an arcuate recess 76 therein which terminates just short of the inner periphery of the ring. At the bottom, the step has a shallow circumferential recess 78 thereabout which has a series of holes 80 in outer peripheral wall thereof that open into the outer peripheral face of the ring.

The attachment ring 54 has a greater diameter than the opening 16 of the box, but has a deeply inset outer peripheral rabbet 82 about the top thereof so that the top can telescope within the step 74 of the casting ring when the remaining flange 84 of the attachment ring abuts against the bottom of the box. Registering holes 86 and 88 in the flange and the bottom of the casting ring, respectively, enable capscrews 90 to be used in securing the rings together when they are mated and abutted inboard of the flange, as shown in Figure 3. In addition, there is an annular dove-tailed groove 92 in the flange of the attachment ring at the radius of the joint between the casting ring and the opening 16 of the box to accommodate an O-ring 94 for sealing the joint.

The attachment ring 54 also has additional holes 108 in the flange 84 thereof which are symmetrically spaced about the outboard portion of the flange to register with the threaded holes 24 in the bottom of the box. When the mold 30 is telescoped in the box, the capscrews 44 are inserted through the holes 108 and threaded into the holes 24 to secure the member to the box.

At its top, the attachment ring 54 is rounded to i GB 2 129 344 A 5 a semi-toroidal configuration corresponding to that of the recess 76 of the step in the ring 46, but smaller in radius than the recess so that an arched continuation 56' of the annular passage 56 is formed between the two rings at the respective rabbets 82, 72 thereof. The attachment ring is also relieved at the inner periphery thereof to have a slightly conical recess 96 about the upper end portion thereof which descends to a greater diameter recess 98 about the bottom portion thereof. The recess 96 is sized to a greater inside diameter than the rounded top of the ring, so that when coolant escapes through the reentrant passage 56, 56, it discharges freely onto the billet between the remaining lip 100 and toe 102 of the respective rings 46, 54. The recess 98 has a plurality of symmetrically angularly spaced, bottom chamfered ribs 104 thereabout to serve as guides for the cap 106 of the associated stool 8, as shall be explained.

There are also four symmetrically angularly offset pairs of cooperating fluid flow passages 110 and 112 (Figure 5) in the rings 54 and 46, respectively, which are individually inter- connected with one another from one ring to the other to supply air and lubricating oil, respectively, to a pair of circumferential grooves 114 and 116 in the vertical wall of the rabbet 60 of the ring. The respective pairs of passages are supplied by a corresponding number of radially outwardly directed holes 118 in the mouth of the opening 16 of the box, which are supplied in turn through the threaded holes 26 in the bottom of the box. Each passage 110 in the ring 54 includes a radially inwardly directed hole 120 in the outer peripheral edge of the flange 84 thereof, which interconnects at its inside end with a vertical hole 122 in the abutting face of the flange. Each passage 112 in the ring 46 includes a vertically upwardly directed hole 124 in the bottom of the ring, which interconnects with an obliquely inwardly directed hole 126 126' in the outer peripheral face of the same. Every other obliquely directed hole 126 terminates in the groove 114, whereas the remaining holes 126'terminate in the groove 116. Otherwise, the respective pairs of passages 110, 112 are similar in that the holes 118 and 120 in the box and flange of the ring 54, are interconnected by registering vertical holes 128 and 130 in the bottom of the box and the abutting face of the flange, respectively; and the holes 122 and 124 in the flange and ring 46 register with one another across the face of the flange. In addition, the holes 118, 120, 126 and 1261 are plugged at their mouth ends. As a result, when the hold 30 is telescoped in the box, fluid fed to the respective holes 26 in the box makes its way through the respective pairs of passages 110, 112 to either the groove 114 or the groove 116, depending on which is the terminus of the passage 112 in the ring 46.

A feed hose 134 coupled to a threaded nipple 136 at each of the holes 26 supplied the respective fluid. Additionally, the holes 130 and 122 are counterbored at the face of the flange 84130 to accommodate a pair of O-rings 132 which are seated in the same to seal the joints between the pairs of holes 128, 130 and 122, 124.

Referring now to Figures 1, 5 and 6 in particular, it will be seen that as the molten metal 138 emerges from the scupper 28, it splays into a metallic mass the meniscus 140 of which tends to contact the peripheral wall 142 of the cavity 143 of the mold 30 in the plane of maximum divergence of the metal. Moreover, the metallic mass has a dive rgentconverg ent cross-sectional outline between the top and bottom of the cavity, the intermediate continuum 144 of which between the planes of maximum divergence and minimum convergence has a peripheral outline corresponding generally to the peripheral outline of the cavity at the peripheral wall 142 thereof.

Meanwhile, there is a pocket 146 of relatively metal-free space formed between the meniscus 140 of the metal and the top corner 71, 142 of the cavity at the overhang 71 of the opening 20.

In the prior art, a stream of pressurized air was delivered to the top of this pocket, and the pressurization of the pocket itself, internally of the cavity, was employed as a means for generating a sleeve-like annulus 148 of gas which would tend to flow downwardly about the metallic mass at the periphery of the cavity, given certain idealized conditions in the pocket. According to the invention, however, a stream of pressurized gassuch as air is pumped into the groove 114, outside of the cavity, and means such as the graphite of the ring 48 are interposed between the groove and the periphery of the cavity to convert the stream into a sleeve-like annulus 148 of fluid at the inner periphery 142 of the ring as the ring discharges the gas into the cavity. The graphite is an air-impregnable facing medium which effectively diffuses and depressurizes the gas so that it can be discharged into the cavity adjacent the plane of maximum divergence as shown. In fact, the gas can be discharged into the cavity opposite the situs of the intermediate continuum 44 itself, as shown, so as to generate the annulus directly at the location where it is needed, regardless of conditions in the pocket.

Meanwhile, lubricating oil is pumped to the upper groove 116 and delivered to the pocket 146 through the upper end portion of the ring.

The grooves 114 and 116 are commonly vertically symmetrically spaced from one another and from the bottoms of the rabbets 58 and 60 of the ring 46. Also, the respective fluids, oil and air, are commonly pumped to the grooves at about 20-30 psi. The graphite is commonly a molded, very fine grain, essentially flawfree, high strength graphite such as the ATJ graphite sold by the Carbon Products Division of Union Carbide Corporation, Chicago, W. Preferably, it also machines to a fine surface finish and has a high thermal conductivity.

In Figures 1-6, the air and oil are delivered to points 114, 116 at the outer peripheral surface of the graphite facing medium 48. In Figure 7, the graphite medium 151 has delivery holes 150 and 6 GB 2 129 344 A 6 152 in the outer peripheral surface thereof, which open into the respective grooves 114 and 116 and extend radially inwardly therefrom, but terminate short of the inner peripheral face 142 of the ring. In this way, the respective fluids are delivered to points within the body of the graphite medium where they can diffuse through the face of the medium over an arc of shorter radius.

If desired, the respective sets of delivery holes may be angled away from the horizontal, such as are holes 154 and 156 in Figure 8, which are angled upwardly from the grooves 114, 116, but again terminate short of the inner peripheral face 142 of the ring 157. Furthermore, depending on the situs of the intermediate continuum 144 of the metal, the oil and air need not be delivered to grooves above and below one another, respectively. In Figure 9, the oil is delivered to the bottom groove 114, and sharply upwardly inclined holes 158 in the outer peripheral surface of the graphite medium 159 are employed to deliver the oil to a level which is disposed above the holes 160 for the air and corresponds to the level of the pocket in the cavity of the mold.

Meanwhile, the air is delivered to the upper groove 116, which in turn delivers the air to the forward ends of the holes 160 for the same.

In Figures 10 and 11. the air is delivered to an annular groove 162 in the outer peripheral surface of the graphite ring 164 itself, and the oil is delivered to a higher groove 166 having a scabbard-like extension 161 of the same extending somewhat downwardly therefrom pclially inwardly of the ring. In addition, the bottom of the top ring 50' has an annular rabbet about the outer peripheral edge thereof and the graphite ring is elevated into the corner of this rabbet, and rabbeted itself to have an annular inner peripheral step 172 about the bottom thereof, the top of which is generally co-planer with the bottom 71 of the top ring. However, the top of the step has a swale-like recess 174 therein which lies slightly ahead of the forward end of the extension 168 of the groove 166. Thus, in this embodiment, oil is bled into the top of the pocket 146 at the overhang itself, as well as into the side of the pocket in the manner of the earlier embodiments. Providing a recessed feed surface 174 for the oil also aids in trapping more oil vapor at the top of the pocket to decrease the cooling effect at that point.

In an alternative form of the invention, the castor oil, peanut oil or other lubricating oil delivered to either of the grooves 116 and 166, is suspended in a highly vaporizable liquid carrier 120 such as alcohol, and the heat generated in the graphite ring during the casting operation is relied on to vaporize the carrier by the time it discharges at the inner peripheral face of the ring. The vapor of the carrier then becomes a part of the annulus 125 about the metallic mass and may substitute entirely for the gaseous medium normally supplied to the grooves 114 and 162, thus obviating any need for delivering gas to the same.

Alternatively, or additionally, the vapor of the 130 carrier may be employed to modify the gaseous/vaporous character of the aannulus, and/or to increase the top cooling of the metallic mass.

Referring now to Figures 12-16, it will be seen that each stool cap 106 rests on a pedestallike base 17 6 and is engaged with the top 178 of the base so as to be capable, within limits, of shifting laterally of the base when the stool is telescoped into the corresponding mold 30 of the device. The top of the base is hollow and has a tapering skirt 180 about the bottom thereof. The top also has an annular rabbet 182 about the top surface 184 thereof, and there is a keyholeshaped hole 186 in the surface which opens into the hollow bore 188 of the top of the periphery thereof. The hole 186 has a circular main section 190 at the periphery of the bore, and an adjoining part circular side section 192 radially inside thereof, the center of which is disposed on the vertical axis of the base.

The top 193 of the cap is cylindrical and sized to telescope within the bore of the casting ring 46. However, the bottom 194 of the cap is more enlarged to a telescope only within the circle of ribs 104 on the attachment ring 54, and there is a shoulder 196 between the two portions of the cap which tapers radially outwardly and downwardly thereof at the same inclination as the bottom 104' of the ribs. The shoulder 196 is also disposed at such a height on the cap that it will engage the bottoms 104' of the ribs before the top of the cap enters the casting ring, thus assuring that the cap is aligned with the ring before it telescopes within the same.

The cap also has a wide annular groove 198 in the bottom surface 200 thereof, which is disposed to register with the rabbet 182 on the top 178 of the base 176 when the two members are coaxial with one another. In addition, at the center of the surface 200, there is a flanged catch 202 which is sized at the flange 204 thereof to pass through the main section 190 of the hole 186 in the base. The flange is also spaced sufficiently below the bottom surface of the cap to be able to slicleably engage with the underside 208 of the top 178 of the base when the surfaces 200, 184 of the cap and base are engaged and the cap is shifted laterally inwardly of the base to engage the members against relative axial displacement, as shall be explained. The shank 206 of the catch, on the other hand, is izecl to fit within the side section 192 of the hole, when the cap is so shifted.

In addition to the cap 106 and the base 197, the stool 8 also comprises a ring 210 which is sized to slideably engage about the top of the base in the rabbet 182 thereof. When the ring is in this position, moreover, it is sized to stand well above the surface 184 of the base and to fit within the groove 198 of the cap when the cap is rested on the surface 184 of the base, coaxially thereof. The ring 210 is also sized to be elevated into the groove, flush with the surface 200 of the cap, as shall be explained. The groove 198, on the other hand, is greatly oversized in widthwise 1 7 GB 2 129 344 A 7 relation to the ring, so that when the cap is rested 65 on the base and the ring is registered with the groove, the cap can shift laterally of the ring for purposes of aligning itself with the casting ring of the device as mentioned. There is a point, however, at which the cap and ring will abut one another, and this point is in advance of the point at which the catch shifts into vertical alignment with the main section 192 of the hole 186 in the top of the base.

The stool 8 is assembled by lifting the ring 210 into the groove 198 of the cap, inserting the catch 202 in the hole 186 of the base, and then while the cap is rested on the top of the base, shifting it laterally thereof to engage the shank 206 of the catch in the side section 192 of the hole. The ring is then released to engage with the step 212 of the rabbet 182, as in Figure 14. In this condition, the cap and base are latched against relative axial displacement, but the cap can slide laterally of the base on the surface 184 of the same, within the limits afforded by the loose engagement between the ring 210 and the groove 198.

When it is desired to remove and replace the cap, for example, with a cap of a different size, the ring 210 is raised into the groove 198 and the cap 90 is slid into alignment with the main section 190 of the hole 186 so that it can be lifted away from the base, as in Figures 15 and 16.

It will be apparent that the invention is applicable to the casting of all cross-sectional outlines including round, square and rectangular; and that it is applicable to both vertical and horizontal casting, including continuous casting.

Also, only a single nipple 136 and passage 110, 112 is needed for each fluid; and many other changes and additions can be made in and to the invention without departing from the scope and spirit of the same as defined by the following claims.

Claims

1. In the direct chill casting of a metal by introducing a mass of the molten metal into the top of an open bottomed mold cavity having a support telescoped therein, chilling the molten metal mass, and reciprocating the mold and support in relation to one another axially of the cavity to form the chilled mass into an elongated body of the metal, the steps of delivering a stream of pressurized gas to a point outside of the cavity, discharging the gas into the cavity at a point on the periphery thereof, and interposing means between the point of delivery and the point of discharge, externally of the cavity, to convert the stream of gas into an annulus of fluid that extends 120 about the metallic mass at the periphery of the cavity.

2. The process according to Claim 1 wherein the molten metal is introduced into the top of the cavity through an opening having a smaller diameter than the peripheral wall of the cavity, and the molten metal splays into a metallic mass the meniscus of which tends to contact the peripheral wall of the cavity in the plane of maximum divergence of the metal, there being a pocket of relatively metal- free space formed between the meniscus of the metal and the top corner of the cavity at the overhang thereof about the opening, and wherein the annulus is generated below the top of the pocket so that the fluid tends to flow upward into the same.

3. The process according to Claim 2 wherein the annulus is generated above the bottom of the mold cavity so that the fluid tends to flow both upward and downward of the cavity, axially thereof.

4. The process according to Claim 2 wherein the gas is discharged into the cavity at a point adjacent the plane of maximum divergence of the 80 metallic mass.

5. The process according to Claim 2 wherein between the top and bottom of the cavity, the metallic mass assumes a divergent-convergent crosssectional outline, the intermediate continuum of which between the planes of maximum divergence and minimum convergence thereof, has a peripheral outline corresponding generally to the peripheral outline of the cavity at the wall thereof, and wherein the gas is discharged from the peripheral wall of the cavity at a point disposed opposite the peripheral outline of the intermediate continuum of the metallic mass.

6. The process according to Claim 5 wherein the gas is discharged at points on the peripheral wall of the cavity circumposed about the entire perimeter of the intermediate continuum of the metallic mass.

7. The process according to Claim 6 wherein the gas is discharged at points on the peripheral wall of the cavity arrayed over the entire height of the intermediate continuum of the metallic mass.

8. The process according to Claim 1 wherein the gas is relatively despressurized and/or diffused as it flows between the point of delivery and the point of discharge.

9. The process according to Claim 1 wherein the molten metal is introduced into the top of the cavity through an opening having a smaller diameter than the peripheral wall of the cavity, and the molten metal splays into a metallic mass the meniscus of which tends to contact the peripheral wall-of the cavity in the plane of maximum divergence of the metal, and wherein a solid but gas-impregnable structural medium is interposed between the point of delivery and the point of discharge that relatively depressurizes and diffuses the gas and discharges it into the cavity at a point adjacent the plane of maximum divergence of the metallic mass.

10. The process according to Claim 9 wherein between the top and bottom of the cavity, the metallic mass assumes a divergent-convergent crosssectional outline, the intermediate continuum of which between the planes of maximum divergence and minimum convergence thereof, has a peripheral outline corresponding generally to the peripheral outline of the cavity at the wall thereof, and wherein the gas- 8 GB 2 129 344 A 8 impregnable medium is positioned at the peripheral wall of the cavity and the gas is delivered to the same so that it discharges at a point opposite the peripheral outline of the intermediate continuum of the metallic mass.

11. The process according to Claim 10, wherein the gas-impregnable medium is extended around the entire perimeter of the cavity and the gas is delivered to the same so that it discharges at points circumposed about the entire perimeter of the intermediate continuum of the metallic mass.

12. The processs according to Claim 11 wlierein the medium is elongated axially of the cavity and the gas is delivered to the same so that 80 it discharges at points arrayed over the entire height of the continuum.

13. The process according to Claim 1 wherein the molten metal is introduced into the top of the cavity through an opening having a smaller diameter than the peripheral wall of the cavity, and the molten metal splays into a metallic mass the meniscus of which tends to contact the peripheral wall of the cavity in the plane of maximum divergence of the metal, there being a pocket of relatively metal-free space formed between the meniscus of the metal and the top corner of the cavity at the overhang thereof about the opening, and wherein a lubricating oil is delivered to the pocket of the cavity.

14. The process according to Claim 13 wherein the oil is discharged into the cavity through the overhang at the top of the pocket.

15. The process according to Claim 13 wherein a portion of the oil vapor is trapped in the top of 100 the corner of the pocket during the casting operation.

16. The process according to Claim 13 wherein between the top and bottom of the cavity, the metallic mass assumes a divergent-convergent 105 cross-sectional outline, the intermediate continuum of which between the planes of maximum divergence and minimum convergence thereof, has a peripheral outline corresponding generally to the peripheral outline of the cavity at the wall thereof, and wherein a gas-impregnable ring is positioned at the top of the cavity to define the corner of the pocket at an annular step therein which is co-planar with the overhang about the top opening of the cavity, the ring is elongated axially of the cavity so that the upper and lower end portions thereof are disposed opposite the pocket and the peripheral outline of the intermediate continuum of the metallic mass, respectively, and the oil and gas are delivered to the ring so that the gas discharges from the same at inner peripheral points on the ring adjacent the continuum, and the oil discharges into the pocket at points thereabove, including at points on the step.

17. In the direct chill casting of a metal by intrducing a mass of the molten metal into the top of an open-bottomed mold cavity through an opening having a smaller diameter than the peripheral wall of the cavity so that the molten metal splays into a metallic mass the meniscus of which tends to contact the peripheral wall of the cavity in the plane of maximum divergence of the metal, there being a pocket of relatively metal- free space formed between the meniscus of the metal and the top corner of the cavity at the overhang thereof about the opening, chilling the molten metal mass, and reciprocating the mold and support in relation to one another axially of the cavity to form the chilled mass into an elongated body of the metal, the steps of delivering a stream of pressurized lubricating oil to a point outside of the cavity, suspended in a highly heat vaporizable liquid carrier, discharging the oil into the pocket of the cavity at a point on the periphery thereof, and interposing means between the point of delivery and the point of discharge, externally of the cavity, to convert the carrier into an annulus of vapor that extends about the metallic mass at the periphery of the cavity.

18. In a metal casting device of the type wherein a mass of molten metal is introduced into the top of an open-bottomed mold cavity having a go support telescoped therein, the molten metal mass is chilled, and the mold and support are reciprocated in relation to one another axially of the cavity to form the chilled mass into an elongated body of the metal, means for delivering a stream of pressurized gas to a point outside of the cavity, means for discharging the gas into the cavity at a point on the periphery thereof, and means interposed between the point of delivery and the point of discharge, externally of the cavity, to convert the stream of gas into an annulus of fluid that extends about the metallic mass at the periphery of the cavity.

19. The device according to Claim 18 wherein the molten metal is introduced into the top of the cavity through an opening having a smaller diameter than the peripheral wall of the cavity, and the molten metal splays into a metallic mass the meniscus of which tends to contact the peripheral wall of the cavity in the plane of maximum divergence of the metal, there being a pocket of relatively metal- free space formed between the meniscus of the metal and the top corner of the cavity at the overhang thereof about the opening, and wherein the gas discharge means and the external conversion means are jointly operable to generate the annulus below the top of the pocket so that the fluid tends to flow upward into the same.

20. The device according to Claim 19 wherein the gas discharge means and the external conversion means are jointly operable to generate the annulus above the bottom of the mold cavity so that the fluid tends to flow both upward and downward of the cavity axially thereof.

2 1. The device according to Claim 19 wherein the gas discharge means are operable to discharge the gas into the cavity at a point adjacent the plane of maximum divergence of the metallic mass.

22. The device according to Claim 19 wherein 7 9 GB 2 129 344 A 9 between the top and bottom of the cavity, the metallic mass assumes a divergent convergent cross-sectional outline, the intermediate continuum of which between the planes of maximum divergence and minimum convergence thereof, has a periphei a] outline corresponding generally to the peripheral outline of the cavity at the wall thereof, and wherein the gas discharge means are operable to discharge the gas from the peripheral wall of the cavity at a point disposed opposite the peripheral outline of the intermediate continuum of the metallic mass.

23. The device according to Claim 22 wherein the gas discharge means are operable to discharge the gas at points on the peripheral wall of the cavity circumposed about the entire perimeter of the intermediate continuum of the metallic mass.

24. The device according to Claim 23 wherein the gas discharge means are operable to discharge the gas at points on the peripheral wall of the cavity arrayed over the entire height of the intermediate continuum of the metallic mass.

25. The device according to Claim 18 wherein the external conversion means are operable to relatively depressurize and/or diffuse the gas as it flows between the point of delivery and the point of discharge.

26. The device according, to Claim 18 wherein the molten metal is introduced into the top of the cavity through an opening having a smaller diameter than the peripheral wall of the cavity, and the molten metal splays into a metallic mass the meniscus of which tends to contact the peripheral wall of the cavity in the plane of 100 maximum divergence of the metal, and wherein a solid but gas-impregnable medium is interposed between the point of delivery and the point of discharge that relatively depressurizes and diffuses the gas and discharges it into the cavity at a point adjacent the plane of maximum divergence of the metallic mass.

27. The device according to Claim 26 wherein between the top and bottom of the cavity the metallic mass assumes a divergent-convergent 110 cross-sectional outline, the intermediate continuum of which between the planes of maximum divergence and minimum convergence thereof, has a peripheral outline corresponding generally to the peripheral outline of the cavity at 115 the wall thereof, and wherein the gasimpregnable medium is disposed at the peripheral wall of the cavity and the gas delivery means are operable to deliver the gas to the same so that it discharges at a point opposite the peripheral 120 outline of the intermediate continuum of the metallic mass.

28. The device according to Claim 27 wherein the gas-impregnable medium extends around the entire perimeter of the cavity and the gas delivery 125 means are operable to deliver the gas to the same so that it discharges at points circumposed about the entire perimeter of the intermediate continuum of the metallic mass.

29. The device according to Claim 28 wherein130 the medium is elongated axially of the cavity and the gas delivery means are operable to deliver the gas to the same so that it discharges at points arrayed over the entire height of the continuum.

30. The device according to Claim 18 wherein the molten metal is introduced into the top of the cavity through an opening having a smaller diameter than the peripheral wall of the cavity, and the molten metal splays into a metallic mass the meniscus of which tends to contact the peripheral wall of the cavity in the plane of maximum divergence of the metal, there being a pocket of relatively metal-free space formed between the meniscus of the metal and the top corner of the cavity at the overhang thereof about the opening, and wherein the device further comprises means for delivering a lubricating oil to the pocket of the cavity.

31. The device according to Claim 30 wherein the oil delivery means are operable to discharge the oil into the cavity through the overhang at the top of the pocket.

32. The device according to Claim 30 wherein there are means for trapping a portion of the oil vapor in the top of the corner of the pocket during the casting operation.

33. The device according to Claim 30 wherein between the top and bottom of the cavity, the metallic mass assumes a divergent-convergent cross-sectional outline, the intermediate continuum of which between the planes of maximum divergence and minimum convergence thereof, has a peripheral outline corresponding generally to the peripheral outline of the cavity at the wall thereof, and wherein a gas-impregnable ring is positioned at the top of the cavity, the ring has an annular step therein which is co-planar with the overhang about the top opening of the cavity, the ring is elongated axially of the cavity so that the upper and lower end portions thereof are disposed opposite the pocket and the peripheral outline of the intermediate continuum of the metallic mass, respectively, and the respective oil and gas delivery means are operable to deliver the same to the ring so that the gas discharges at inner peripheral points on the ring adjacent the continuum, and the oil discharges into the pocket at points thereabove, including at points on the step.

34. A stool for telescoping into the mold cavity of a metal casting device, comprising a pair of operatively coaxially disposed cap and base members which are slideably engageable with one another at mutually opposing surfaces thereon and equipped with cooperatively engageable male and female catch means on the surfaces thereof, the female catch means having a laterally offset groove therein on the axis of the members, and the male catch means being insertable in the female means when the members are engaged with one another at the surfaces eccentrically of the axis, and-engageable in the groove when the members are laterally displaced in relation to one another to a point at which they assume concentricity with the axis, GB 2 129 344 A 10 and first and second latch means which are shiftable laterally and axially of the axis, respectively, to latch and unlatch the members against relative axial and lateral displacement, respectively, when the members are engaged with one another at the surfaces and relatively daterally displaced to and from said point, and maintained at said point, respectively, the second I itch means and the cap member being engageable with one another in the latched condition of the cap member to allow for limited lateral displacement of the same in self-aligning with the device.

35. A billet casting mold for a bottom loaded coolant box casting device of the type wherein the coolant box has registering top and bottom openings in the chamber thereof, the top opening of which has a shoulder thereabout and the bottom opening of which opens into the bottom of the box and has a greater diameter than the top opening of the chamber, comprising a pair of cooperatively engageable top and bottom rings, the top ring of which is adapted to be inserted upwardly into the chamber through the bottom opening thereof and abutted against the shoulder about the top opening, the top ring having apertures in the body thereof which are adapted to open into the bottom of the chamber when the ring is inserted into the chamber and abutted against the shoulder, and an arcuate step thereon that overhangs the apertures and is circumposed about the inner periphery of the top ring at a level adapted for discharging a curtain of coolant liquid onto the emerging billet from the chamber, the bottom ring being adapted to telescope within the top ring and to cooperate with the step in forming an annular passage for the coolant therebetween which communicates with the apertures in the body of the top ring and extends upwardly 85 therefrom to a point at which it then curves reentrantly downwardly to the inner periphery of the top ring for discharge of the curtain, and the bottom ring having a flange thereon which is engageable with the bottom of the box to locate one ring within the other when the passage is formed.

36. In combination, a bottom loaded coolant box casting device of the type wherein the coolant box has registering top and bottom openings in the chamber thereof, the top opening of which has a shoulder thereabout and the bottom opening of which opens into the bottom of the box and has a greater diameter than the top opening of the chamber, an apertured hot top superposed thereabove, the aperture of which registers with the top opening of the box but is smaller in diameter than the same, and a flanged insulative refractory scupper telescoped in the aperture, the flange of which is disposed below the overhang of the aperture in the top opening of the box.

37. A process of direct chill casting of a metal substantially as described hereinbefore with reference to the accompanying drawings.

38. A metal casting device substantially as described hereinbefore with reference to the accompanying drawings.

39. A metal casting device substantially as described hereinbefore with reference to the accmpanying drawings and as shown in Figures 1 to 5, and Figures 12 to 16, and either Figure 6, Figure 7, Figure 8, Figure 9 or Figures 10 and 11.

40. A stool for telescoping into the mold cavity of a metal casting device substantially as described herienbefore with reference to and as shown in Figures 1, 3, 4 and 12 to 16 of the accompanying drawings.

41. A billet casting mold for a bottom loaded coolant box casting device substantially as described hereinbefore with reference to and as shown in Figures 1 to 5 and either of Figure 6, Figure 7, Figure 8, Figure 9, and Figures 10 and 11.

42. A bottom loaded coolant box casting device in combination with a refractory scupper substantially as described hereinbefore with reference to and as shown in Figures 1 to 5 and either of Figure 6, Figure 7, Figure 8, Figure 9, and Figures 10 and 11. 90

43. Any other novel feature or combination disclosed hereinbefore or shown in the accompanying drawings.

Printed for Her Majesty's Stationery Office by the Courier Press, Leamington Spa, 1984. Published by the Patent Office, 25 Southampton Buildings, London, WC2A.1 AY, from which copies may be obtained.

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