US3225395A - Expansible template with hinged skirts - Google Patents

Description

D 1965 J. D. KARMERZE EXPANSIBLE TEMPLATE WITH Filed March 4, 1963 ETAL HINGED SKIRTS 4 Sheets-Sheet 1 j MI;

i )Qmerze qnd Morris 5. Mal/n lNVENTORS ATTORN IVS Dec. 28, 1965 J. D. KARMERZE ETAL 3,225,395

EXPANSIBLE TEMPLATE WITH HINGED SKIRTS Filed March 4, 1963 4 Sheets-Sheet 2 I 1 Mg! FIG 2 Joseph D. Karmerze and Morris- 51 Mal/n INVE NTO RS ATTORNEYS Dec. 28, 1955 J. D. KARMERZE ETAL 3,225,395

EXPANSIBLE TEMPLATE WITH HINGED SKIRTS Filed March 4, 1963 4 Sheets-Sheet 3 FIG 3 Joseph D. Karmerze and INVINTORS KITOR EYS Dec- 2 1965 J. D. KARMERZE ETAL 3,225,395

EXPANSIBLE TEMPLATE WITH HINGE!) SKIRTS Filed March 4, 1963 4 Sheets-Sheet 4 Mil/Mm l 0W humm" L m, 2

24 Joseph D. Karmerze qnd Moms 5! Mal/n INVENTORS ATTORNEYS United States Patent 0 3,225,395 EXPANSIBLE TEMPLATE WlTH HINGED SKIRTS Joseph D. Karmerze, West Chester, and Morris 5. Malin,

Exton, Pa, assignors to Lukens Steel Company, Coatesville, Pa, a corporation of Pennsylvania Filed Mar. 4, 1963, Ser. No. 262,415 2 Claims. (ill. 22-9) This invention relates to an improved apparatus for the operation of a collapsible form known in the art as an umbrella for producing hot tops.

One of the principal objects of the invention is to provide means for producing a hot top by a collapsible form which is known in the art as an umbrella which uniformly distributes the gas into the sand mixture that solidifies and forms the hot top.

An additional object of the invention is to provide a collapsible umbrella provided with gas chambers or jackets forming the side walls, ends, and corners, each having a plurality of gas outlets in the said chambers or jackets.

Yet another object is to provide uniform feeding of gas through the side walls and ends of an umbrella particularly in locations near the corners and even on the sloped bottom surface known in the art as the feather edge.

A further object is to provide an improved means for controlling the movements of the sides and ends of the umbrella for quickly collapsing and expanding the same permitting a much facilitated stripping and form removal operation by having the bottom skirts hinged.

Other objects will appear hereinafter throughout the specification.

In the drawings:

FXGURE l is a side elevation view partly broken away to show the interior structure of our novel umbrella;

FIGURE 2 is a partially broken end elevational view of the umbrella shown in FIGURE 1, in expanded position;

FIGURE 3 is a view somewhat similar to FlGURE 2, partly in section, showing the parts in contracted position;

FIGURE 4 is an enlarged, partially broken, underside view of the structure of this invention; and

FIGURE 5 is a detailed view, mostly in vertical section, of certain of the parts in expanded position.

In making steel ingots, it is common practice to provide in the upper portion of the ingot mold, a supplementary or additional mold known as a hot top. The function of the hot top is to minimize and contain the shrinkage cavity which occurs as the ingot cools in the mold. Hot tops generally consist of a refractory type of material and may be placed on top of the mold, or inserted partially or entirely into the mold.

It is customary in the art to mold in place hot tops which are composed primarily of a mix of sand, moisture, and sodium silicate (commonly known as water glass). A collapsible form, which is known in the art as an umbrella, is placed within the ingot mold and expanded so that a mold is formed around the periphery of the upper inner sides of the ingot mold, with such inner sides providing the outer sides of the mold, and the surfaces of the umbrella providing the inner sides of the mold. The aforesaid mixture of sand and sodium silicate is dumped into the space enclosed by the umbrella and ingot mold, leveled, and tamped.

The umbrella of the prior art has a number of small outlet holes or orifices in the side walls that form the inner sides of the hot top mold and each of said holes are connected to a tube which in turn connects to a manifold having a source of carbon dioxide. Once the sand is in place, carbon dioxide is vented from the aforesaid orifices into the sand and sodium silicate mix. When this occurs,

sodium carbonate and silica are formed. The silica, in the presence of the moisture in the sand, forms a matrix, called a gel, of growing silica fingers which mesh and intertwine throughout the moisture, trapping it, and cementing adjacent sand grains. The gassing of the mix by the carbon dioxide is completed in approximately 20 to 40 seconds. If too much carbon dioxide is used, more sodium carbonate is formed which is further reacted upon by the excess carbon dioxide to form, together with moisture in the mix, sodium bicarbonate. If excess moisture is not available for this process, the necessary Water will be drawn from the newly formed silica gel, and with the water drawn out of it, the gel collapses, destroying its function as a cementing bond between the grains of sand. Following the gassing, the hot top is permitted to harden and the umbrella is collapsed and pulled up and from around the inner portion of the hot top. The hot top is then cleaned of all debris, loose sand, etc., and is ready for the pouring of the steel. When the ingot mold is filled with molten steel, it will be appreciated that the hot top mass is thereby heated, and any sodium bicarbonate which may have been previously formed in the mix, is transformed back into sodium carbonate, water, and carbon dioxide. The water given off in this thermal decomposition is concentrated as a wet active steam about one-fourth to one-half of an inch from the inner face of the hot top and saturates this area in a lamina fashion to cause a swelling and weakening in this plane. This outer layer then may peel off in a characteristic fashion since there is little or no grain bonding to resist such action. This peeling or spalling, of course, may go much deeper if enough sodium bicarbonate has been formed in the area involved. The spalling is objectionable and may cause a rejection of part or all of the steel from an ingot wherein excessive or undesirable spalling has occurred.

The most desirable 'hot top is one which is easily formed, will harden to a maximum degree, will contain the molten steel with minimal or no spelling, and which, once the ingot has been formed and taken from the ingot mold, may be broken up and dislodged from the mold without undue difiiculty. \Vith present methods, in order to obtain the desired type of hot top, great care must be taken in the gradation of the sand particles to avoid an excess of fines and clay, or of too large grain sizes. It has been found that fine sand accentuates the poor gas distribution. Thus the clays and silts in the sand where there are large surface areas and absorption qualities tend to rob the mix of the moisture necessary for the silica gel formation. The extreme fineness also causes the sodium silicate to cover more area to the point where same particles have no covering at all or the sodium silicate is dispersed in ultra thin films of decreased effectiveness. In such case, the carbon dioxide reaction proceeds at a greater rate to produce the effects of overgassing. If clays are present, the permeability of the sand is lowered to where the carbon dioxide finds it diflicult to diffuse through the mix and, as a result, concentrates in the inner face of the hot top causing again overgassing eifects in the surface area.

Aside from the foregoing, there are other factors which affect the quality of the hot tops produced by present methods, such as for example the atmospheric temperature and humidity when the mix is prepared and the mold is formed. Thus, it has been found that if a sand which is too coarse is chosen, the sodium silicate on each particle of sand is thicker and not as Widely dispersed as with finer sand. As a result the carbon dioxide reaction proceeds very slowly and with the present methods, the hot top does not gain enough initial strength to stay in the mold and hence collapses or falls in the ingot mold immediately after the umbrella is removed, which happens particularly in the winter time. Moreover, ex pansion of the larger grains during the pouring of the heat, tends to cause a true type of spalling as will be found with silica brick. A very high permeability of a coarse mix permits carbon dioxide to channel easily through the shortest route to the atmosphere whereby relatively large volumes of the hot top are under gassed and soft.

It will be appreciated from the foregoing that in order to. obtain a desirable quality of hot tops by the present methods, specifications must be followed very closely. Very little, if any, variation can be permitted in the complicated process or otherwise the risk of rejects makes the otherwise economical process unsuitable.

It has occurred to the inventors that a primary difficulty in present methods is the poor gas distribution inherent in its design. The gassing holes are relatively far apart (sometimes 8 inches), which in itself causes an erratic flow of gas to the sand mix to the back portion of the hot top. Sometimes the gassing holes will be plugged or the closures leading thereto are closed due to handling when the umbrella is expanded in the mold. Such conditions, of course, aggravate the gas distribution problem. It has been found that by providing double walls in the umbrella to receive the carbon dioxide and to allow it to expand and equalize, and an increased number of orifices in the outer wall, the effectiveness and reliability of the process is greatly increased to a substantial and unexpected extent. The resulting umbrella appears stronger, is easier to manufacture, has less gas tubing and therefore less possibilities of malfunction, permits the direct gassing of areas around the corners of the mold not previously possible, and consistently produces substantially improved hot tops.

Referring now to the drawings, the top portion 10 of an umbrella A is provided, as shown in FIGURE 1, with hinges 12 for the ends 13 of the umbrella. As shown in FIGURE 3, the sides 14 are also hinged by hinges 16. Hingedly connected to the sides 14 by further hinges 18 are serrated skirts 20. The serrations or undulations of these skirts 20 are adapted to engage similar serrations or undulations in the walls of the ingot mold 60. As shown in FIGURES 2, 3, 4 and 5, the sides 14, the ends 13, and the corners 42 are of a double wall configuration; the spaces provided between the aforesaid double walls permitting the carbon dioxide to expand and equalize itself before it passes into the material to harden the hot top mass during the formation thereof. It will be noted that there are separate spaces 22 for the sides 14, and 24 for the skirts 20. In umbrellas of the prior art, the skirts 20 and the sides 14 were integral and no gas outlet orifices were provided in the skirt portions. With skirts 20 separate and hinged, not only is the gas distribution improved, but in addition, it is not necessary to pull in the sides 14 so far, with the commensurate dislocation of tubing within the umbrella, when the umbrella is folded and disengaged from the hot top. If desired the sides 14 may be absolutely vertical or inclined slightly inward from top to bottom and hinges 16 may be eliminated. The perforations 26, 28, and 30, are inclined with respect to the outer walls so that the carbon dioxide is urged into the mix in a downward direction in the vertical portion of the inner sides of the hot top and more or less horizontally in the inclined bottom portion of the hot top (see FIGURE 5). Each of the spaces 22 in the sides, 20 in the skirts, 21 in the ends, and 23 (shown cut away in FIGURE 4) in the corner, is connected to a manifold pipe by means of flexible sections or tubes 34. The pipe 40 is connected through the connection 41 to a source of carbon dioxide gas. The tubes 34 are connected to rigid sections 38 leading from pipe 40 and to further rigid portions 36 leading from the sides, skirts, ends and corners. Thus, carbon dioxide may be lead from a source (not shown) into the manifold 40, thence to the tubes 34 and finally into the double walls at the sides, ends and corners (guards) of the umbrella, both in its collapsed and non-collapsed positions.

It will be understood that although an oblong rectangular shaped umbrella is shown in this disclosure, the umbrella may be other shapes, such as square, polygonal, or round.

Referring now to FIGURE 1, and FIGURE 4 which show an underside partial view of the umbrella, it will be seen that the corners 42 as well as the sides 14 and the ends 13, are actuated by a series of levers indicated generally by reference numeral 44. These levers comprise a pair of vertical bars 45 which extend to the top of the umbrella and are connected to a cross-member 46 which is attached to a hook or loop 48. The vertical bars 45 are connected to a cross bar 47. A series of telescoping, spring loaded bars 49 are pivoted on one end to the cross bar 47 and on the other end to the nearest skirt 24) or corner 42. It will be noted that the lever 44, when lowered with the umbrella expanded, leaves the bars 47 and 49 in a toggle type of relationship so that the umbrella will not accidentally collapse. A chain 51 connects the end 13 with the bar 47. This causes the end piece 13 to pull in as the mechanism is collapsed. The sides 14 and the corners 42 are urged outward when the mechanical linkage 44 is pushed downward. Springs (not shown) housed in the arms 49 are compressed in this opening action and thus put tension on the corners 42 and walls 14 and thus hold the form in contact with the walls of the ingot mold. Other springs 53 are resistently held by lugs extending from stanchions 55 and nuts 57 engaging the ends of rods 59 which are connected to the sides 14. Springs 53 are used to limit the outward travel of the side walls during opening.

In operation, the umbrella A is engaged at loop 48 by a chain fall or the like and lifted free of the surface. When it is lifted, it is automatically collapsed by raising the levers 44. It will be noted that the chain 51 will pull the ends 13 inward. The overhead supporting structure designated generally as 58 is then placed on the upper edges of an ingot mold 60 with the umbrella A being inserted into the mold. The position of umbrella A within mold 60 can be adjusted as desiredby the adjustment of crosslbeam 61 on legs 63 by inserting pins 64 in the appropriate holes 65 for the desired height. The levers 44 are then permitted to lower by manually pushing down on loop 48 whereby the corners 42 and the skirts 20 are urged outwardly and the umbrella A is thus expanded to form the inner portion of a mold for mix 66 which is placed therein and tamped. Carbon dioxide is then supplied at a pressure of 25 to 50 pounds per square inch to permeate the mix as has been previously described. When sufificient silica gel is formed to cement the mix together, the umbrella may be removed, which can be accomplished by merely lifting same by loop 48 thus pulling the levers 44 upward to collapse the umbrella from the hot top so that it can be lifted upward and removed from the vicinity of the ingot mold 60.

It will be noted from FIGURES 1 and 2 that the orifices 26 in sides 14 and the orifices 30 in end 13 may be disposed relatively near the vertical edges of the sides thus permitting the distribution of carbon dioxide in the adjacent corner areas. This was not possible with the prior art since the corners 42 would, when they were moved inwardly, interfere with the tubular connections to the orifices in the area involved.

The foregoing detailed description has been given for clearness and understanding only, and no unnecessary limitations should be understood therefrom, for modifications will be obvious to those skilled in the art.

We claim:

1. An apparatus for manufacturing hot tops for casting molds comprising a form, said form having a plurality of collapsible sides, hinged skirts depending from said sides, manifolds in said sides and skirts having inner and outside Walls, a substantially horizontal manifold pipe disposed at the upper portion of the form, flexible pipe means for connecting a source of hardening fluid for a hot top mass from said manifold pipe to said manifolds, and a plurality of spaced outlets from said manifolds located in said ouside walls for releasing said fluid from said manifolds at spaced points along the said outside Walls 2. The structure of claim 1 wherein said outlets comprise openings extending at an acute angle to the plane of said outside walls.

References Cited by the Examiner UNITED STATES PATENTS Sandin 15l04.18

Griifiths 15--104.18 Bo Magnus Tigershiold.

Vayda 22 9 Graef 22-9 FOREIGN PATENTS France.

Claims (1)

1. AN APPARATUS FOR MANUFACTURING HOT TOPS FOR CASTING MOLDS COMPRISING A FORM, SAID FORM HAVING A PLURALITY OF COLLAPSIBLE SIDES, HINGED SKITS DEPENDING FROM SAID SIDES, MANIFOLDS IN SAID SIDES AND SKIRTS HAVING INNER AND OUTSIDE WALLS, A SUBSTANTIALLY HORIZONTAL MANIFOLD PIPE DISPOSED AT THE UPPER PORTION OF THE FORM, FLEXIBLE PIPE MEANS FOR CONNECTING A SOURCE OF HARDENING FLUID FOR A HOT MASS FROM SAID MANIFOLD PIPE TO SAID MANIFOLDS, AND A PLURALITY OF SPACED OUTLETS FROM SAID MANI-

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