US2507082A - Core materials - Google Patents

Description

Patented May 9, 1950 CORE MATERIALS Jim E. Allison, Elmhurst, 1u., assignor to The Quaker Oats Company, Chicago, 111., a corporation of New Jersey No Drawing. Application June 21, 1946, Serial No. 678,352

2 Claims. 1

The present invention relates to core materials, and more particularly to cereal core binders employed in their production.

My invention is concerned with the production of a corn product core binder. In the past various corn products have been proposed by the prior art as foundry core binders. For example, a first type of prior art product is produced by sending a heavy slurry of mill starch from a corn wet processing plant over the hot surfaces of internally. heated rolls. The contact of the mill starch slurry with the heated surfaces causes the gelatinization of the starch and the formation of a flaked product which is then ground to a fine powder. A second type of prior art product is made by moistening degerminated corn and subjecting the moistened product to a heated roll surface whereby the starch in the degerminated ground corn is gelatinized and whereby the whole product is flaked. The flaked gelatinized product is then ground to a fine powder.

I have found that ground degerminated corn can, when properly processed, be made into an emcient core binder having qualities superior to that obtained with corn product fractions of the prior art. Heretofore in making foundry cores for use in the production of castings, it has been the practice to mix core sand with a variety of dry or liquid binders, namely: various corn product fractions, pulverized cereals, pulverized foundry pitch, rosin or casein, sulphite pulp waste liquor, molasses, or various oils such as linseed, soybean or other vegetable oils. The mixture of sand and binder is then moistened with sumcient water so that it can be inserted into core boxes of various shapes and sizes corre sponding to the shape and sizes of cavities it is desired to produce by means of the cores.

When the corebox is removed, the grains of sand must be bound together by the binder so as to permit handling in an approved manner and transferring to an oven. In the oven the cores are baked to expel the water, drive off volatile eonstituents and give a core capable of withstanding the pressure encountered in casting operations. In casting, the heat of the molten.

metal burns out the binder, the gases from which. vent through the core and molds, leaving the core My corn flour produces cores or molds possessing much greater strength than cores or molds employing cereal binders which have been processed according to the methods described in the prior art.

Accordingly one of the objects of my invention is the treatment of a ground degerminated corn product by a simple and inexpensive method whereby it will be adapted for use as a core binder.

A further object is to produce an improved high tensile strength sand core material such as is used in the casting of metals.

Another object of my invention is the production of a ground degerminated corn core binder having qualities superior to that of other corn product core binders.

Still another object is the development of a process which makes possible the use of a corn milling product which in normal times is a drug on the market. During the dry milling of degerminated corn a certain percentage of a more or less finely ground product is obtained, which according to its degree of fineness, is known as corn flour or corn cream meal. That portion which passes through a mesh screen is classified as a corn hour and the product which passes through a 46 mesh screen and is retained on a 95 mesh screen is commonly known as corn cream meal although sometimes broader ranges of particle size may be included under that terminology. My process enables the production of a valuable and efiicient high quality core binder from corn cream meal.

In practicing my invention, I have found that com cream meal containing 10 to 15% moisture can be readily and economically pelleted. Any suitable means of pelleting may be employed, but I prefer to extrude the material through a die fitted with a revolving knife which is so ad justed that it cuts the pellets to an appropriate length. For ease of handling, I prefer pellets 5%" in diameter and in length. While the use of steam is not necessary in the extrusion process. it is preferred since it apparently lubricates the dies, thus making for more emcient operation.

A charge of pellets produced as above described is placed in a pufling gun. This gun may be any of the conventional types of equipment used for the pulling of cereals such as rice, oats, wheat, corn, etc. Examples are the Anderson pulling gun such as that described in U. S.= Patent 1,725,171 and the Plews pufling gun described in U. S. Patent 2,116,212. superheated steam is allowed to enter the gun chamber at a temperature of 620 F. The steam passes through the pellets and expels any air present in the chamber. The cover of the pufllng gun or chamber is then closed and the internal pressure allowed to build up to 175 lbs. per square inch. The chamber is maintained at this pressure for about three minutes whereupon the pressure is suddenly released. The resulting puffed corn cream meal cereal is then conveyed to a rotary drier and dried to a moisture content of about 8%. The dried material is then ground or pulverized to a flour of about 60 mesh. In the puihng process the temperature should'be above the gelatinizing temperature of the starch in the cereal. A workable range is obtained by using superheated steam within a temperature range.of 375 to 800 F. and a pressure range of 75 to 200 lbs. per square inch.

Cores manufactured from the above puffed pulverized corn cream meal are characterized by greater strength as indicated particularly by dry compression, air set compression and dry tensile strength tests. The following tests show the core binding qualities obtained with the pufied and then ground corn cream meal of the present invention as compared with flaked and pulverized corn products of the prior art.

A mixture of one part of pufied corn cream meal,- 50 parts of sand and 1.5 parts of water was mixed for 8 minutes and produced a core which, when allowed to set in air for 30 minutes at room temperature, gave an air set compression of 16.8 lbs. per square inch and when baked for two hours at 400 F. gave a dry compression of 244 lbs. per square inch. When 30 parts of sand and 1 part of linseed oil were added to the above ingredients and another core formed and baked for one hour at 400 F., the resulting core had a tensile strength of 224 lbs. per square inch.

When a flaked and powdered mill starch product (unpufled) was subjected to the same series of tests the air set compression was 8.8, the dry compression 100 and the dry tensile strength 140 lbs. per square inch. It is thus seen that the pulled corn cream meal product had a dry compression strength or twice that or the unpuiled product and an air set compression and dry tensile strength of somewhat less than double than that of the unpuil'ed product.

when a flaked and powdered product prepared from degerminated corn grits (unpufled) was subjected to similar sets of tests under identical conditions the dry compression. air set compression, and dry tensile strengh was 115, 12.6 and 181 lbs. per square inch, respectively. Here, too, the puffed corn cream meal product is distinctly superior.

It is apparent from the above data that the pufied corn cream meal core binder is superior to both of the other com product binders. In place of puii'ed corn cream meal one could use pulled corn flour and obtain similar advantageous results.

While I have in the above description disclosed what I believe to be a preferred and practical embodiment of my invention it will be understood that the specific details, including the technique by which the process is carried out, are by way of example and not to be construed as limiting the scope of theinvention.

I claim:

1. A casting core material comprising a mix ture of sand, a drying oil, and degerminated, pelleted, puffed and pulverized corn flour.

2. A casting core material comprising a mixture of sand, a drying oil, and pulverized corn product formed by pelleting, steam pufllng and comminuting a degerminated, comminuted corn product.

JIM E. ALLISON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 707,892 Anderson Aug. 26, 1902 921,030 Wagner et a1 May 11, 1909 1,429,879 Hill Sept. 19, 1922 2,181,372 Kellogg Nov. 28, 1939 2,206,369 Salzberg July 2, 1940 2,289,030 Miller July 7, 1942 2,388,904 Collatz Nov. 13, 1945 FOREIGN PATENTS Number Country Date 515,470 Great Britain Dec. 6, 1939

Claims (1)

1. A CASTING CORE MATERIAL COMPRISING A MIXTURE OF SAND, A DRYING OIL, AND DEGERMINATED, PELLETED, PUFFED AND PULVERIZED CORN FLOUR.