US1871324A - Ingot mold - Google Patents

Description

Patented Aug. 9, 1932 UNITED s'rA'ras PATENT OFFICE EDMUND J. KAUFFMAN, or GIRABD, OHIO, ASSIGNOR T VALLEY MoULn AND IRON CORPORATION, OF HUBBARD, OHIO, A CORPORATION OF {NEW YORK "meow MoLD No Drawing.

The present invention relates broadly to metallurgy and more especially to a coating liable to badly cut the side wall and the molten metal is liable to weld or to infiltrate in 16 cracks in the walls of the mold so that when the ingot is stripped the mold is defaced and may be ruined. The present invention overcomes the difficulties of the known art by applying a novel 20 coating material to the mold, which material is consumed by the heat of the molten metal and leaves an extremely low amount of residual ash. The heat conductivity of the coat- I ing is low and the consumption of the coating is also relatively slow so that by the time the coating has been burned from the surface of the mold, the steel or other metal has cooled to such an extent as to relieve the mold of severe thermal work and, furthermore, the small quantity of residual ash left by the burning of the coating. acts as a protecting shield between the hot steel or other metal and the matrix of the mold.

The ingot cast in a mold having its matrix covered with the novel coating benefits to a larger extent than the mold itself. As steel or other metal is teemed into a mold, the molten metal at the ascending contact line Of mold and ingot often rises or travels ahead of the main mass of metal in a comparatively thin sheet or boot. This is caused by the agitation of the molten metal by the disengagement of escaping gases, and also by reactance to the ferro-static or metallo-static pressure released on impact. Where the mold walls are not coated, the thin sheet of molten metal or boot mentioned above, solidifies almost instantly due to'the influence of the comparatively cold mold walls. As 59 the main mass of molten metal overtakes the Application filed February 28, 1931. Serial No; 519 270.

solidified boot it may not re-melt the previously formed metallic skin or boot, thus causing serious ingot surface defects technically called scabs. The novel coating of the present invention has a very low heat conductivity which markedly delays the cooling action of the mold walls on the molten steel during the first few instants of con-' tact. Thus the pre-advancin metal skin or boot cannot" chill as rapi and conse quently as much aswhere the mold walls are bare, thus allowing. the 'main mass of rising metal to readily re-melt the pre-skin or boot, and hence allowing the formation'of an ingot surface very much smoother and less subject to the so-called scabby'ingot surface that may and often does cause defective product. At the same time, the ingot is not contaminated with highly silicious or other refractory mineral ash residues due to the very low ash content of-the novel'coating of the present invention. The present invention comprises more especially the laying of a coating of carbo-hydrate' or cellulose material on the matrix surfaces of the mold. This material may take the form of paper stock usually referred to in the art as stuff. The preferred form of the material is known as .half-stufi', which is cellulose fibers,- usually wood pulp, which may be made into a viscous liquid by the addition of water. This liquid is sulficiently diluted with water so that the material may be sprayed upon the walls of the matrix of a mold to form a layer of paper which is tightly attached to the walls without the use of pastes or glues of any kind. Preferably, the spraying is done by a spraying apparatus of the ordinary atomizer type in which the viscous material israised from it source of supply through a pipe over which a blast of air is directed, so that the material rises in the supply pipe by an aspirator action and is broken up or atomized by the blast of air under pressure.

Theliquid of a. satisfactory consistency may be made by utilizing 3% to 3%% by weight of half-stuff to 97% to 96 A;% of water. The spraying of the material on the mold preferably is done when the molds I are heated to about 150 F. to 300 F. If

. the mold is too cold, the material does not tend to dry quickly, whereas if the mold is too hot, steam tends to form with excessive rapidity beneath the sprayed layer and blisters may occur. It takes about five grams of half-stud to coat one square foot of mold surface. This produces a coating of about 1/64th of an inch in thickness as a minimum; Greater thicknesses may be obtained by the sprayingof successive coats.

-, Under certain conditions, 1t may be desirable to mix wood lignin with the liquid in order to. obtain a better binder. This wood lignin solution is a by-product of wood pulp paper mills. It has also-been found that the material sprays a little better by mixing soap in the solution and under certain conditions improved results may be obtained by utilizing a metallized soap, that is,'a soap containing, for example, iron chloride or aluminum chloride which produces a metallic substance residue when the lining is consumed, and this residue provides an addition to the protecting layer between the side wall of the mold and the molten steel. It has also been determined that wood pulp flour may be -tion is the coating of the matrix of an ingot used tomix with awater solution and may j 'ne gned as n coating.

principal feature of the present invenmold with a carbohydrate material and more specifically a cellulose material which may be applied to the mold as a relatively thin coating that dries as a sheet which does not tend to run under heat as is the condition with tar, etc., and which leaves a very small amount of ash which does not contaminate the steel,

, as is the case with lime or other. mineral washes. It is also of importance in the pres- Y ut case that the material being used is a very poor conductor of heat so that the material is actually consumed before a substan 'filling of the mold by the molten steel as'is the case with mold washes which are not applied .as sheet coatings. The intimate contact between this coating and the sidewall y of the mold i s such that the material stays in place during pouring, does not tend to run 5 final shield between the hot ingot and the tial. amount of heat from the molten steel in place andacts as Having described my invention, I claim: 1. The combination of an ingot mold for receiving high melting point molten metal, and a paper liner therefor covering the walls of the mold cavity.

2. The combination of an ingot mold for receiving high melting point molten metal, and a cellulose material liner therefor covering the walls of the mold cavity. 3. The combination of an ingot mold for receivinghigh'melting point molten metal, and a wood pulp liner therefor covering the walls of the mold cavity.

4. The combination of an ingot mold for receivinghigh melting point molten metal, and a liner therefor covering and adhering to the walls of the mold cavity, said liner being composed of half-stuff impregnated with a mineral salt.

.5. The combination of an ingot mold for receiving high melting point molten metal, and a liner therefor covering and adhering to the-walls of the mold cavity, said liner being composed of a cellulose material imdown to the bottom of the mold or to float on top of the molten steel due to heat,-and.the residual ash also stays it to a certain extent acts as a lubricant and .to another extent acts to spacethe ingot a mold.

short distance from the side wall of the