US2661298A

US2661298A - Composition for use in sand molding

Info

Publication number: US2661298A
Application number: US116618A
Authority: US
Inventors: Connor B Shanley
Original assignee: Individual
Current assignee: Individual
Priority date: 1949-09-19
Filing date: 1949-09-19
Publication date: 1953-12-01
Anticipated expiration: 1970-12-01

Description

Patented Dec. 1, 1953 UNITED STATES PATENT OFFICE COMPOSITION FOR USE IN SAND MOLDING Connor B. Shanley, Kirkwood, M0.

N Drawing. Application September 19, 1949, Serial No. 116,618

2 Claims. 1

This invention relates in general to certain new and useful improvements in methods of sand molding and compositions for use in conjunction therewith.

In the preparation of sand molds for use in the manufacturing of metallic castings, it is standard practice to lay a pattern on a molding board and place the drag portion of the flask around it. Molding sand is then riddled or sifted over the pattern until the drag is partially filled. and this sand is rammed. Thereupon, additional sand is sifted into the drag and rammed and this process is repeated as many times as may be desired until the sand projects somewhat above the edge of the drag. The surplus or projecting sand is struck off with a straight edge until it is flush with the edge of the drag. Loose sand is then sprinkled on this surface and a bottom board placed on it. Depending upon the nature of the mold, the drak may be vented in any appropriate manner.

The drag, with the pattern and bottom board in position, is turned over and the molding board removed, exposing the joint or parting face and cope side of the pattern. This parting face is usually finished by slicking with a broad trowel until the surface is very smooth and firm, whereupon it is dusted with parting sand and the cope portion of the flask put in place. The cope is then filled and rammed in substantially the same manner as the drag.

When the ramming is completed, the cope is lifted offv for finishing the mold. Various conventional operations are then performed, such as removal of the pattern, installation of chaplets, formation of a runner from the gate to the mold cavity, and any smoothing or facing operations which the particular circumstances may require. In the course of these operations, the parting face of the cope is usually slicked down, so as to make a very smooth juncture with the parting face of the drag. In any case, when all the necessary molding operations are completed, the cope is replaced in position on top of the drag and weighted down or the cope and drag are suitably clamped together to receive the molten metal. In the present state of molding technique, it is common practice to use removable flasks and, in order to do so, provision must be made to hold the parts of the mold in precise alignment against lateral shifting along the parting faces.

At the present time, it is common practice to insert dowel pins or spikes through the two parts of the mold, but such means do not provide true precision of alignment. Furthermore, dowel pins and the like become foreign substances which render the sand unfit for re-use and must be removed by methods which have been found to be comparatively expensive and time-consuming.

It is, therefore, one of the primary objects of the present invention to provide a simple, quick, and economical method of securing the parts of a sand mold together which makes it possible to achieve precise alignment of the cavity-forming portions of the mold.

It is another object of the present invention to provide a method of securely joining the separate parts of a sand mold together over substantially the entire area of their parting faces without the introduction of foreign sub stances which will render the molding sand unfit for subsequent use or will require the sand to be subjected to a reclamation process which is both expensive and time-consuming.

It is also an object of the present invention to provide a unique composition which may be employed for joining together the matching parts of a sand mold and holding them securely in precise alignment during subsequent handling and use. I It is a further object of the present invention to provide a composition of the type stated which will not contaminate the sand or otherwise ren der it unfit for subsequent re-use.

It is likewise an object of the present invention to provide a composition of the type stated which will become intermixed with the molding sand after it is removed from around the finished casting and will improve the molding qualities of such sand when it is later re-used.

With the above and other objects in view, my invention resides in the novel processes and compositions of matter presently described and pointed out in the claims.

Broadly speaking, the present invention resides in coating the parting faces of the cope and drag or similar cavity-forming components of a sand mold with an adhesive consisting of a mixture of bentonite, water, and curbay. Curbay, as defined on page 118 of the Zimmerman and Lavine Handbook, published 1946 by Industrial Research Service, is a dark-colored liquid of a syrupy consistency, obtained from the liquid residue in the manufacture of alcohol from molasses and consists of complex mixtures of vegetable gums, unfermentable sugars, inorganic salts, and water. This adhesive is capable of becoming thoroughly intermixed and, in effect, disappearing into the molding sand after it has been knocked loose from the finished casting without impairing the quality of the sand for subsequent molding use. Thus, the adhesive substance will in the first instance serve to hold the mold parts together, but will not become a foreign substance in the molding sand upon subsequent re-use.

For purposes of illustration and not by way of limitation, the following are specific examples of an adhesive material forming a part of the present invention:

In. preparing the above compound, the bentonite and water are mixed and the curbay added slowly to form a thorough homogeneous liquid. Thereupon, the seacoal, which is finely ground or pulverized, low-volatile, substantially sulphurfree coal, is stirred into the mixture to produce a fluid product having a specific gravity ranging approximately from 60 degrees B. to 100 degrees B. It should be understood that the foregoing percentages by weightv have been found to give preferred forms of adhesive composition but variations in these percentages have been found to be fully effective over fairly wide ranges.

In accordance with the present invention, the parting face of the cope and drag are made smooth and hard through jolting or ramming against a smooth plate or board. If necessary, the parting faces are carefully slicked down with a hand trowel or by any other suitable method so that the two parts of the mold will fit tightly and precisely together. The smooth parting faces are then coated with the adhesive of the present invention and the twoparts of the mold placed together. When the adhesive has set or dried, the flask is removed and it will be found that the two parts of the mold are securely adhered together. In fact, the adhesive of the present invention is so highly efiective that the two parts of the mold will be extremely hard to separate or displace from each other almost immediately after the two adhesive coated surfaces are pressed together.

Subsequently, after the casting has been poured and cooled, the molding sand may be knocked away or otherwise removed from the casting and the adhesive material will become uniformly and intimately mixed with the sand in such a manner that it will not in any way interfere with the subsequent use of the sand. As a matter of fact, the residual components of the adhesive, which are thus incorporated into the sand upon subsequent use, will improve, rather than impair, its molding qualities.

It should be understood that changes in the methods, compositions, percentages, and combinations above set forth may be made without departing from the nature and principle of my invention.

Having thus described my invention what I claim and desire to secure by Letters Patents is.-

I. An adhesive for joining together the parts of a sand mold consisting of the following composition:

Percent by weight Bentonite 10 to 20 Water 40 to 55 Curbay 30 to 2; An adhesive for joining together the parts of a sand mold consisting of the following composition:

Percent by weight Bentonite 10 to 20 Water 40 to Curbay 30 to 45 Seacoal 2 to 5 CONNOR B. 'SHANLEY.

References Cited in the file Of this patent UNITED STATES PATENTS Number Name Date 632,579 Lundin Sept. 5, 1899 1,576,248 Robeson Mar. 9, 1926 1,673,357 Hanley June 12, 1928 1,837,877 McDowall Dec. 22', 1931 1,867,382 Sampson July 12, 1932 1,889,905 Saeger Dec. 6, 1932 1,893,683 Saeger Jan. 10, 1933 1,897,149 Saeger Feb. 14, 1933 2,169,279 Oyster Aug. 15, 1939 2,201,131 Jungersen May 14, 1940 2,270,770 Ray Jan. 20, 1942 2,348,155 Shanley May 2, 1944 2,380,945 Collins Aug. 7, 1945 2,525,175 Keyser Oct. 10, 1950

Claims

1. AN ADHESIVE FOR JOINING TOGETHER THE PARTS OF A SAND MOLD CONSISTING OF THE FOLLOWING COMPOSITION: