US3904166A

US3904166A - Hot top liner unit with flexible plastic envelope

Info

Publication number: US3904166A
Application number: US271848A
Authority: US
Inventors: Melvin Eugene Wadsworth
Original assignee: Combustion Engineering Inc
Current assignee: Combustion Engineering Inc
Priority date: 1972-07-14
Filing date: 1972-07-14
Publication date: 1975-09-09
Anticipated expiration: 1992-09-09
Also published as: CA982323A

Abstract

An insertable liner unit is provided for hot topping in ingot molds and the like. The liner unit is comprised of a plurality of side board members contained in end adjacent relationship within a jacket of flexible material. The jacket freely contains the side board members therewithin, requiring substantially no direct bond between the jacket and the board members. The jacket is formed of a flexible sheet-like material which may flex to permit adjacent side board members to be moved from a flat end-to-end position to an end adjacent angled geometry for installation in a liner in a hot top. The jacketed side board members provide an integrally formed liner unit requiring only one person to manipulate and install the hot topping. The jacket fully surrounds and is sealed about the side board members contained therewithin thereby preventing their dislodgement from the jacket. Further, the material of the jacket may be impermeable to water and comprise a heat sealable and shrinkable plastic such as polyethylene. Use of such jacketing material facilitates fabrication of the liner unit and prevents the side board members from absorbing moisture.

Description

United States Patent [1 1 Wadsworth HOT TOP LINER UNIT WITH FLEXIBLE PLASTIC ENVELOPE [75] Inventor: Melvin Eugene Wadsworth,

Chardon, Ohio [73] Assignee: Combustion Engineering, Inc.,

Windsor, Conn.

[22] Filed: July 14,1972

[21] Appl. No; 271,848

[52] US. Cl 249/197; 53/28 [51] Int. Cl. B221! 7/10 [58] Field of Search 249/106, 197-201; 53/28, 29; 229/14 C; 206/46 FR, 56 A. 56 AB [56] References Cited UNITED STATES PATENTS 3,162,539 12/1964 Repko r. 53/29 X 3,216,689 1 H1965 Carpenter 249/201 3,338,019 8/1967 Trcwella ct a1.v 53/28 X 3,389,534 6/1968 Pcndleton u 229/14 C UX 1390507 7/1968 Repko 53/29 X 3,478,999 11/1969 Charman et a1. 249/201 3,605,374 9/1971 Mueller ct a1 206/56 A UX FOREIGN PATENTS OR APPLICATIONS 234,289 6/1964 Austria 249/198 832,555 4/1960 United Kingdom 249/197 Sept. 9, 1975 Primary ExaminerRobert D. Baldwin [57] ABSTRACT An insertable liner unit is provided for hot topping in ingot molds and the like. The liner unit is comprised of a plurality of side board members contained in end adjacent relationship within a jacket of flexible material. The jacket freely contains the side board members therewithin, requiring substantially no direct bond between the jacket and the board members. The jacket is formed of a flexible sheet-like material which may flex to permit adjacent side board members to be moved from a flat end-to-end position to an end adjacent angled geometry for installation in a liner in a hot top. The jacketed side board members provide an integrally formed liner unit requiring only one person to manipulate and install the hot topping. The jacket fully surrounds and is sealed about the side board members contained therewithin thereby preventing their dislodgement from the jacket. Further, the material of the jacket may be impermeable to water and comprise a heat scalable and shrinkable plastic such as polyethylene. Use of such jacketing material facilitates fabrication of the liner unit and prevents the side board members from absorbing moisture.

7 Claims, 5 Drawing Figures PATENTED 75 SEEET 1 [1F 2 HOT TOP LINER UNIT WITH FLEXIBLE PLASTIC ENVELOPE BACKGROUND OF THE INVENTION The present invention relates generally to hot topping for ingot molds and more particularly to an insertable liner unit for use therein. More particularly still, the invention pertains to a hot topping liner unit in which a plurality of side board members are retained within a jacket of flexible material.

Hot topping of ingot molds is both commonplace and necessary and involves placing an insulative, sometimes refractive, sometimes exothermic material intermediate the molten metal at the top of an ingot and an outer casing therearound. This material most often takes the form of side boards or panels which are inserted into a hot top casing or directly into the ingot mold itself. Each side board or panel member generally conforms in shape and lateral dimension to an interior face of the hot top casing or ingot mold. A variety of methods have evolved for inserting, positioning and restraining these side board members as a hot top liner prior to and during pouring of the ingot. In some instances, discrete side board members are used and require the efforts of two persons or considerable coordination by one to insert. In an attempt to facilitate the insertion and positioning of the side board members comprising a hot top liner, integral liners have been developed which incorporate a plurality of side board members into a unitary structure prior to their positioning in the hot top. One such example is to be found in US. Pat. No. 3,216,689 to Carpenter, wherein a plurality of insulating side board members are joined as a unit by a single strip cardboard backing to which the individual members are bonded. A further example in which plural side board members have been combined into a unitary structure prior to their insertion into the hot top is seen in U.S. Pat. No. 3,478,999 to Charman et al. In the Charman patent, the individual side board members are molded together as a unitary structure with frangible means intermediate adjacent side board members permitting relative angular movement of the individual members in order to effect insertion as a hot top liner. The panel unit of the Charman patent includes hinge means, preferably of wire interconnecting the individual side board members to retain them in adjacent relationship when the frangible portions are broken. Such means, while facilitating installation of the hot top liner, have objectionable shortcomings.

These liners are generally of a type which may not be reused and their destruction to a certain degree is permissible. However, in those liners which employ metal hinge means, some of the hinge metal usually is to be found imbedded as an impurity in the periphery of the finished ingot in the region of the hot top. This metal must be removed and may require scrapping that portion of the ingot, thus creating needless waste. The expense of this waste varies, of course, with the area affected and the quality of the ingot metal.

Employing cardboard or similar material as a backing and hinge, such as disclosed in the Carpenter patent, does not present the problem of metal impurities in the ingot; however, additional time, effort and materials are required to effect the bond between the backing sheet and the individual side board members. The backing material and the composition of the side board members are usually such as to require significant amounts of a bonding agent. Additionally, careful positioning of the several side board members on the backing is required at the time of bonding.

A further deficiency in prior hot top liners arises if the composition of the side board members is such that they exhibit significant hygroscopic characteristics. In such cases, the side board members often pick up considerable moisture between the time they are manufactured and when the ingot is finally poured. This increased moisture content may cause partial deterioration of the side board and any bond which might exist with a backing member, but more importantly, the moisture will be released as a vapor at the time the ingot is poured. This vapor may enter the ingot, causing voids and may include gases of a corrosive nature.

SUMMARY OF THE INVENTION According to the invention, there is provided an improved liner unit for use in ingot mold hot topping. The liner unit of the invention is comprised of a plurality of end adjacent side board members contained by and retained within a container or jacket of flexible material. In the preferred embodiment, substantially no direct bond exists between the jacket and the plural side board members contained therewithin, thereby eliminating attendant material and manufacturing considerations. The material jacketing the board members serves as a hinge, permitting relative angular movement between adjacent side board members. The unitary structure resulting from the jacketing of the board members is easily manipulated by an individual person for insertion into the mold or hot top casing. The jacket material is selected to permit relative folding of adjacent side board members while maintaining their unitary structure and without adding unwanted inclusions to the ingot during the molding process. The jacket may also be selected to provide differing degrees of impermeability to moisture.

In its broadest sense, the invention provides a flexible jacket-type container about the several side board members arranged in end adjacent relationship. The jacket material completely envelops the several side boards and is sealed to restrain them in position therewithin against dislodgement during handling. The several board members may be in contact with or connected to one another or they may be separated by dividing the jacket into subcompartments, each subcompartment containing a board member.

In one embodiment of the invention, the jacket material is substantially impermeable to water and is sealed in water-tight relationship about the entirety of the several side board members, enveloping them therewithin. This arrangement permits the several side board members to be handled, shipped and installed as a unit while also preventing significant moisture absorption during these operations. A heat sealable plastic, such as polyethylene, is preferred as the water impermeable blanketing material. A material such as polyethylene additionally may be heat shrunk into close fitting relationship about the several board members.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a partial isometric view of an ingot mold showing the insulating liner of the invention inserted therein for hot topping.

FIG. 2 is an isometric view of one embodiment of the liner of the invention during fabrication.

FIG. 3 is an isometric view of an alternate embodiment of the liner of the invention following completion of fabrication.

FIG. 4 is an isometric view of an alternate embodiment of the liner of the invention showing a jacket which remains open at its upper end.

FIG. 5 is an isometric view of the liner of FIG. 3 with the section in phantom representing the unfolded or flat liner and the solid lines representing the liner angularly folded for insertion into a mold.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Turning now to the drawings, there is shown in FIG. 1 an ingot mold of the big-end-up type such as are generally used in the formation of high-grade ingots. A liner comprising one or more liner units 12, constructed in accordance with the invention, is inserted into either the upper region of ingot mold 10 or within a hot top casing, not shown, to create a hot top zone 14. The hot top serves to delay the solidification of the metal contained within it so that molten metal can feed downwardly into the main body portion of the metal ingot to compensate for shrinkage during cooling, thereby preventing the formation of shrinkage cavities in the final ingot. Mold 10 of FIG. 1 is formed of four major interior faces 20, one of which is not shown, and four minor corner faces 22, two of which are not shown.

The liner unit 12 consists of a plurality of side board members 16 disposed in end adjacent relationship and contained with a jacket 18 of flexible material which contains the several boards 16 and retains them as a unitary structure. Usually a liner unit 12 will include at least as many side board members 16 as there are major interior faces 20.

FIGS. 2 and 3 depict a liner 12 in accordance with one general embodiment of the invention wherein jacket 18 completely retainingly cnvelops the several side board members. Referring to FIG. 2, a liner unit 12 is shown in fabrication. Four side board members 16, corresponding to the interior faces 20 of mold 10 within the hot top zone 14, are aligned in flat, end-to end relationship. Each board member 16 has opposite ends 24 which, in this embodiment, are connected with the adjacent end 24 of the next succeeding board by a frangible connecting portion 26. Frangible portion 26 is easily broken to permit relative angular movement of adjacent board members. Each board member 16 has substantially planar front and back faces and 27 respectively, which face inwardly and outwardly respectively when the liner unit 12 is positioned within mold 10. The end face 28 adjacent the front face 25 and at each end 24 of each board member 16 is inclined or tapered away from front face 25 toward the back at an angle which, in cooperation with the corresponding end face angle of the adjacent board member 16, permits the boards to be positioned within the mold 10 with their adjacent end faces 28 in contact. The end faces 30 adjacent the back face 27 of each board member 16 are inclined or tapered away from back face 27 toward the front at an angle permitting substantially flat Contact of the end faces 27 with the corner faces 22 of mold 10 when liner 12 is positioned therewithin. These end face angles may obviously be varied to accommodate the interior geometry of the mold or hot top casing.

The materials and compositions from which the side board members I6 are made may vary depending on the requirements of liner 12 as a hot topping liner. Liner I2 is generally required to have highly insulating characteristics. A typical such board composition includes mineral wool or asbestos, an organic fibrous material such as wood or paper pulp, refractory filler ma terials and a binder. In the event liner I2 is to have exothermic characteristics, an exothermic material such as aluminum may be added to the side boards 16 at or near their front faces 25.

The side board members 16, whether joined by a narrow frangible portion 26 as in FIG. 2, or independent and separate as in FIG. 3, are preferably formed by a vacuum or pressure wet molding operation well-known in the art.

While in its broadest sense the invention is intended to include jacket I8 generally containing the several side board members 16, one preferred embodiment requires that the jacket freely envelop the board members with substantially no direct bond occurring therebetween. Jacket 18 freely envelops the several side board members 16 in the FIG. 2 embodiment and is sealed thereabout to restrain the board members therewithin, thus forming an integral unit of the several side board members which comprise liner 12.

While a variety of techniques might be employed for placing jacket 18 about side board members 16, one preferred to completely envelop the side boards simply requires that the material ofjacket 18, having a surface area large enough to more than completely enclose the several side board members 16, be disposed in an open flat position on a work surface; the several board members 16 be positioned in end adjacent relationship thereon; the free area of the jacket material be drawn entirely over the uncovered areas of the board members into overlapping or contacting relationship with itself; and that a seal be made between the overlapping or contacting portions of the jacket to retain the side board members therewithin. The seal, indicated as 34 in FIG. 3, may be continuous along the region ofjaeket overlap or contact, or it may be intermittent, as determined by the type of jacket required for a particular liner I2. While jacket 18 may snugly envelop side members I6, there is no, or substantially no, bond between the board members and the jacket. Thus, the jacket 18 is said to freely contain the board members 16 even though there may be contact therebetween. The material of jacket 18 and the type of seal 34 used to close the jacket about the side board members 16, may be varied somewhat as dictated by economics and the need for water-tight envelopment of the board members.

Various of the side board constituents, such as paper pulp, asbestos and the like, tend to give the board pro nounced hygroscopic characteristics. Such boards may absorb considerable moisture following their manufacture and prior to the pouring of the ingot. As a consequence this moisture, usually water, is evaporated when the molten metal contacts side board members I6 of liner I2. This vapor often creates undesirable voids or bubbles in the finished ingot and additionally, may be corrosive to the metal of the ingot.

Where it is important to restrict the amount of moisture absorbed by the side board members 16, the material of jacket 18 is selected as one which is substantially impervious to moisture, particularly water. While a variety of treated papers or fabrics might be used, various heat scalable plastics will also provide the desired barrier against moisture intrusion and additionally, a fluid tight seal is easily obtainable through the application of heat to the area to be sealed. The plastic may also be of a type which shrinks upon the application of heat. Examples of such heat shrinkable and scalable plastics which may be safely used in molten metal environments include polyethylene, polystyrene and the like.

The unsealed, or open, perimeter areas 32 of a plastic jacket 18, as seen in FIG. 2, are overlapped to form a complete closure about the several side board members 16 and heat, and pressure if needed, is applied to these areas of overlap to melt and fuse the plastic into a fluid tight seal about the board members. A further advantage is realized where a snug fit of the jacket about the board members is desired if certain types of heat shrinkable plastics, such as polyethylene, are used for jacket 18. Following the application of localized heat in the sealing operation, the jacketed liner 12 is passed through a heat tunnel or similar well-known device causing the jacket material to shrink into close contact with the board members. Alternately, liner 12 might be formed by inserting the board members 16 serially into any one of a variety of preformed commercially available plastic tubes of sufficient length and diameter to accommodate the several board members. The plastic tube may then be heat sealed about the board members as described above and additionally, if ofa heat shrinkable nature, may be shrunk into snug contact with them. It will be recognized that the walls of the tubes are of pliable, sheet-like plastic material.

FIG. 3 depicts an alternate arrangement of the embodiment in which the jacket completely envelops the several side boards. In this alternate arrangement, sev' eral side board members 16 of liner unit 12 are separated from one another and have no intermediate frangible connecting portion such as seen in FIG. 2. These board members 16, seen arranged for insertion into the mold in FIG. 5, have only a front inclined end face 28 at each end thereof. This geometry is provided for use in a mold or hot top casing having only major side faces and no minor corner faces. It will be realized that the individual board members may be tapered inward in the downward direction to provide a snug fit according to the taper of the mold.

The seal 34, which closes and retains jacket 18 about the side board members 16, is extended, in FIG. 3, into the regions intermediate adjacent board members to divide the envelope created by jacket 18 into subcompartments, with each subcompartment restrainedly containing an individual side board member 16 therewithin. This arrangement maintains a certain degree of alignment and spacing between adjacent side boards 16 to facilitate folding or forming the liner 12, as shown in FIG. 5, to form all or a portion of a generally tubular liner for hot topping. If the side board members 16 of liner unit 12 include frangible connecting portions 26, the jacket subcompartment does not exist and the frangible portions are easily broken to effect the abovedescribed angular folding. In every embodiment,jacket 18, in addition to joining the several side board members 16 into the unitary structure of liner unit 12, further serves as a hinge which permits the abovedescribed angular folding of the boards while maintaining them in end adjacent relationship.

The material of jacket 18 is generally capable of yielding sufficiently to accommodate the limited stretching which might result when liner unit 12 is bent from the unfolded to the folded position. If excessive stretching is anticipated, the seals 34, in jacket 18, adjacent the side board member ends 24, may be spaced sufficiently from the side board ends to allow the neces sary relative movement between the board members and the blanket.

If the side board members 16 of liner l2 consist only, or substantially only, of materials which are not particularly hygroscopic, or if the board members are never exposed to a moist or humid environment, or if some degree of moisture absorption by the boards is tolerable, the material of jacket 18 need not be impermeable to moisture. Rather, a material such as kraft paper, burlap, linen or other similar flexible material may be employed to hingedly interconnect the several side boards.

The jacket 18 and seal 30 are both sufficiently strong to retain the side board members therewithin in end adjacent relationship prior to, during and after the folding of liner 12 to provide the insulating hot topping liner. The material ofjacket 18 is sufficiently flexible to permit the requisite relative folding of adjacent board members 16 while serving to hingedly interconnect them. Seal 34 may be provided in a variety of ways, as by stitching, mechanically fastening, fusing or chemically bonding or cementing the overlapping or contacting areas 32 of jacket 18 to one another.

There is depicted, in FIG. 4, another general embodiment of the liner unit 12 of the invention wherein jacket 18, which freely contains the several side board members 16, does not fully envelop the several board members in sealed relationship thereabout. Rather, the top of jacket 18 remains unsealed and open, thereby permitting any or all of the side board members 16 to be removed therefrom and replaced in the event of their becoming damaged prior to insertion of liner unit 12 in mold l0 and pouring of the ingot. Jacket 18 may extend at least the full height of the side board members 16 to contain them fully therewithin or it may extend only a part of the way, as shown in FIG. 4, in order to conserve the material used in fabricating the jacket. The jacket material, as earlier described, is sheet-like and pliable. In accordance with the invention,jacket 18 need only be of a size, in length, height and width, to contain and retain the several side board members 16 therewithin in end adjacent relationship prior to and during insertion of the unit into the mold 10. If the top ofjacket 18 remains open and unsealed, it will be evident that the jacket will contain the bottom or lower portion of the side boards and that an increased degree of care may be required in handling the liner unit 12 formed thereby to prevent dislodging the boards from the jacket.

As was described in the discussion of the FIGS. 2 and 3 embodiments, the jacket 18 of the FIG. 4 embodiment may comprise a single large compartment containing the several board members 16 or it may be divided into subcompartments or pockets, each containing a board member. Accordingly, the several board members of a liner unit may be initially joined or separated.

Because the jacket 18 in the embodiment of FIG. 4 is not sealed entirely about the side board members 16 but permits later insertion of the board members thereinto, it may be formed without the board members included therewithin and the board members added subsequently. ln fabricating jacket 18, the seals 34 will be made as described hereinbefore; however, if a single piece of material is used to form the jacket, only the ends 36 will require sealing and the top 38 will remain open and unsealed except where required for subcompartmentation, if used.

Because the plural side board members which comprise insulating liner 12 are contained within jacket 18 to form an integral package, folding and installation of the liner is facilitated. normally requiring the services of only one person. Further. the absence of metallic hinge means avoids the problem of waste metal inclusion in the ingot. It will be appreciated that a complete insulating liner for hot topping might consist of plural end adjacent liner units 12, each including plural side board members 16 within individual enveloping blankets 18; however. a single liner unit of unitary construction and including therewithin all of the side board members required for the installation will usually provide the most satisfactory means for insulating the hot top region of a mold or hot top casing.

It will be understood that the embodiments shown and described herein are merely illustrative and that changes may be made without departing from the scope of the invention as claimed.

I claim:

1. An insertable liner unit for use in hot topping, said unit comprising a plurality of end adjacent hot top side board members and a jacket of flexible heat sealable plastic completely enveloping and retaining therewithin said side board members in substantially end adjacent relationship, said side board members being angularly movable relative to one another from a flat endto-end position to an end adjacent angled geometry for installation in a liner in a hot top.

2. A liner unit as defined in claim I wherein said jacket freely contains said side board members therewithin and is substantially independent of any direct bond therewith.

3. A liner unit as defined in claim 2 wherein said jacket material is a heat shrinkable plastic.

4. A liner unit as defined in claim 3 wherein said heat sealable and shrinkable plastic jacket material is polyethylene.

5. A liner unit as defined in claim 4 wherein the number of side board members comprising said liner unit is greater than two.

6. A liner unit as defined in claim 5 wherein frangible integrally molded portions of the side board members interconnect the adjacent ends of the plural side board members, said frangible portions being breakable to allow said relative angular movement of said members from said flat position to said angled geometry as a liner in a hot top.

7. A liner unit as defined in claim 2 wherein said jacket is continuous about the entirety of said plurality of sideboard members and said plastic is substantially impermeable to water and is sealed in fluid tight relationship about the entirety of said plural sideboard members.

Claims

2. A liner unit as defined in claim 1 wherein said jacket freely contains said side board members therewithin and is substantially independent of any direct bond therewith.