US2875073A - Core binder and process of making cores - Google Patents

Description

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United States Patent Qfifice 2,875,073 cons BINDER AND PROCESS OF MAKING CORES Charles J. Gogek, Brookfield, Ill.,asslgnor to Corn Products Refining Company, New York, N. Y., a corporation of New Jersey No Drawing. Application May 23, 1955 Serial No. 510,583

4 Claims. (Cl. 106-384) This invention relates to new core binders and to a new process for making cores suitable for use in fabrication of metal castings.

In ordinary practice of making cores, 100 parts of sand is mulled with about 1 part by weight of cereal binder, 3 parts by weight of water is added and mulled into the mixture, followed by addition and mulling of 1 part by weight of core oil. In some cases, where the cores must have special properties, other binders, such as bentonite, may also be used. The mulling period depends on the type of machine used, and the proportion of binders depends on the design of the core, the properties of the binders and on the metal to be poured, all of which are recognized by those skilled in the art. The mulled mixture is rammed or blown into a corebox which is subsequently opened, the core is carefully removed and transferred to a hot oven where it is baked. The variables in these operations are likewise recognized by those skilled in the art. After removal from the oven and cooling, the core is an accurately formed hard object which will withstand rough handling. In use, it must retain its shape as molten metal flows and solidifies around it, and should then collapse to an easily removable mass asthe binders slowly burn off.

In the description of ordinary practice given above, the cereal binder, such as pregelatinized starch, is added primarily so that the freshly formed damp core possesses sufiicient wet or green strength to retain its shape until it is placed in the oven. In addition, the baked core must have high dry or baked strength, most of which is provided by the core oil in the typical process described.

The components added for green strength and baked strength may operate against each other- Thus, core oils decease green strength of sand mixtures. This in some instances is a serious disadvantage, and it is one object of this invention to eliminate such disadvantage by replacing the oil with a binder which doesnot depreciate the green strength.

For foundry use, there is a need for a single dry, freefiowing binder which will part both green and dry strength tocores. A further object of this invention is to provide an easily prepared, dry, free-flowing binder which imparts both green and dry strengthto cores.

' Cores liberate gases as moltenmetal flows around them, and since these gases may be trapped in the ,castgroup specified hereinafter.

2,875,073 Patented Feb. 24, 1959 ings, any means to minimize the volume of gases evolved is of great importance in enabling foundrymen to fabria cate solid metal entirely free frompin-holes and blow-holes. A further object of this invention is to decrease volume of gases liberated by sand cores baked with organic binders, particularly cereal binders and sugars. Further, the invention is useful for decreasing volume of gases liberated by core pastes and core washes containing organic binders when the pasted or washed cores are baked. Further objects will appear hereinafter in the description which follows.

When certain sugars in combination with cereal binder and certain salts or acids are substituted for conventional core oils in typical core sand mixtures, such as those described above, I have unexpectedly found that satisfactory green strength and high baked strength of the cores may be obtained. In addition, "I have unexpectedly found that cores prepared using a mixture of cereal binder and certain sugars in combination with certain acidsfor salts bake just as rapidly or significantly faster than those made with cereal binder and core oil. Further, I have unexpectedly foundthat baked cores prepared using a mixture of cereal binder and certain sugars in combination with certain acids or salts liberate substantially less gases than those made with cereal binder and certain sugars in the absence of the adjuncts hereinafter specified. These findings constitute a pronounced departure from ordinary foundry practice andwould not be anticipated by those skilled in the art. When cereal binder is blended with the sugars hereinafter specifiedand certain salts, there is obtained a dry, free-flowing composition of matter which is much easier to handle thancereal binder and core oil. r

The present invention comprises a mixture of suitable proportions of cereal binder, ucertain sugars which are specified hereinafter, and an adjunct selected from the Cereal binders are well known in the art and include pregelatinized starches and pregelatinized starchy flours, the latter usually containing small amounts of protein or fiber. In addition, the term cereal binder includes dextrins which may be employed for certain specific uses.

By the term sugar, I means those monoand disaccharides ofan aldose or ketose character, or such non-reducing saccha-rides which may be hydrolyzed under conditions of use herein described to give aldose or ketose saccharides. For example, sucrose is elfective as a component of the described binder and is claimed in this invention, while sorbitol is not.

The sugars which I prefer are dextrose, sucrose, and

fructose or mixtures thereof, but maltose and lactose are Sirupswhich may be made by hydrolysis of starch or from cane sugar by appropriate treatments are-also--effective in carrying out this invention. Dextrose greens or hydrol may be treated to prevent crystallization of the dextrose contained therein by boiling them with acid or alkali in accordance with known methods. These byproducts may be less efiective than dextrose or sucrose, as is apparent from the data in Table II, but are within the scope of this invention because of their economic advantages.

The chemical adjuncts which are suitable for purposes of my invention are sulfuric acid; phosphoric acid; any chemical or mixture of chemicals which generates either or both of these acids under the conditions of use, such as ammonium sulfate, ammonium acid sulfate, aluminum sulfate, alums, e. g., ammonium aluminum sulfate, ammonium .rer t taaad th alkali permit-ates. am-

m ta 1d. ho 1, 1d hy r ci i c' q. as s atsh r' a asi raiafqrm ld h d an n nil mig lq ra mixt of natetq ma h dr ch ri acid; .b i aci T e a r mentioned compounds may act as catalytic agents to promote condensation of sugars, or may decomposeunder the conditions used to produce .such catalytic agents. However, I do not wish to be limited by any tlzteory of the operation of the aforementioned compounds.

Ammonium sulfate is the preferred adjunct, among the reasons being its effectiveness, cheapness, stability, noncorrosive character and theease with which itmay be blended with ,the other components of the core.

Obviously, anyq wfc em nt qn djun wh c are suitable forthe purposes of myjnvention should be used in proportions which yield optimum benefits from their use. These proportions maybe diiferent for each adjunct.

The amounts of adjuncts, cereal binders and,sugars may vary widely. For 100 parts of sand, 0.25 to 2 parts of cereal binder, 0.5 to parts of sugar and from,0.002 to O.l5 part by weight of adjunct p er part by weightof sugar may be used. The amount of water may vary from 1.5 to 6.0 percent of the sand. All ,partsabovespecified are parts by weight. In general, volume of gases liberated by baked cores as well as heating time required for cores to attain peak strengths are decreasedas the proportion of the preferred adjunct in thesand is-raised. .Qne t peofmi l ma p dus a r ha na diffe e ma im m ke s ng h a the le HOW- eve hos s i led n h w me nso th -t a h n of this invention and a few simple tests, will be able to arrive at proportions most suitable for their own operl fi nfi a 'lt has been proposed heretofore to, use 1 certain carbo hydrates with or without 'coreoils in core binders, also to usevarious adjuncts therein. See for example B ritish "Pa e t 515,470; U. S. Patent 2,215,825; and G'erman Patent 55 2,3 80. However, as will be apparent from the information herein set forth, my invention differs radically from the prior art and produces unexpected improvements thereover.

The invention will be further illustrated by the examples set forth below which are intended for illustrative and informative purposes and not in any Waylimitin the invention. i

This example ShOWSZ'hOW SIIQHEih of baked cores is increased when certain adjunctsare used with the binders.

-=Various core mixtures containing cereal binder, sugar, and sugar in combination with anadjunct were prepared as follows:

A-weighed amount of American Foundr'ymens Society standard50 70 sand was pouredintoamuller. To this was added 1 percent by weight of pregelatipiz ed cereal binder made in'accordance with the principles of US. Patent 1,939,97 3 and sold under a the trademark ,Mogul.

Then 1 percent by weight (if a sugar (nature of which is described inTable II-)-was-added. Thismixture-served as the control. Identical mixtures of cereal binder and sand were then made to which was added 1 percent by weight of a mixture prepared by thoroughly blending 100 parts of sugar and the amount of an adjunct as set forth in the table.

In each case the whole mass was mixed for a suitable period, the muller stopped, 3 percent by weight of water added, and the mixture mulled again for a suitable period. Where sulfuric acid, phosphoric acid, pyrophosphoric acid, and hydrochloric acid were employed, these were added as solutions in the water, rather than as a blended mixture with the sugar. Specimen cores were prepared according to a method recommended by the American Foundrymens Society (Foundry Sand Handbook, sixth edition, published in 1952 by American Foundrymens Society, Chicago), and were baked in an oven at 400 F.:l0 F.,-f or the length of time shown in Table II. Such cores were tested for tensile strength by the -method described in .the aforementioned handbook, the results being shown in Table II. After the baking was completed, he specimensyvere removed from the oven, cooled to room temperature, andthe breaking strength was determined with an appropriate machine.

7 The results set forth in'IablelI.

In those cases shownin- Table II where a liquid binder was used, cereal binder was mulledwiththe sand, water was added and mulled, and then the liquid binder was added and mulled. If the adjunct was a dry powder, this s added w h .th fis sa inde theadinn w available asaliquid, it was added dissolved in .the. water.

EXAMPLE 2 This example reveals the superiorgreen strength properties of cores preparedawith cerealtbinderin combina tion with a sugar and an adjunct .as compared to vthose prepared with cereal binder .used in.-combination.,with -a core oil. The core sandmixture containing cereal binder, sugar and adjunct was prepared, as described in Example l. Green strength and dry.- strength were determined in accordance with procedures described in the Foundry Sand Handbook mentioned above. sResultsare set forth in TableI, i-where percentages .of binder and adjunct are based on .sand.

.Ia le I GREENLSTRENG'FH. OF "OOREJM'IXEP'URES AN'D BAKED STRENGTH OF ooausrnurannousmomwo amp-an Thisexample showshow .volume of gases liberated by a baked core. isdecreased when thepreferred adjun ct was-used with cereal binder and dextrose. Several baked cores were prepared in the manner de- ,scribed in Example 1. They'we're broken inthemachine used for testing tensile strength and thetwo halves were rubbed together to loosen some of the sand. ,Asatnple of the loose sand was weighedintoa combustionboatand subjected to a temperature of l850-F. in a combustion furnace, the gas released was, collected and measured in accordance with the proceduredescribed in the Foundry Sand Handbook, previously mentioned. The results are listed in Tahlelllwhere percentages of binderandadjunct are based onweightof sand.

, Table II TENSILE STRENGTH F BAKED SPECIMEN OORES Parts of Baking Tensile Sugar Chemical Added Chemical] Time. Stre th,

100 Parts Home p.e

of Sugar Dextrose hydrate Noun 0 120 Do on o 1 170 Ammonium sulfate 2 1 170 do 3 0. 5 155 .do 3 1 230 do 4 1 210 do 5 1 220 .do 0. 5 208 do 10 1 188 do 0. 5 170 .do 15 1 163 Ammonium 2 1 109 Acid sulfate 3 1 225 Ammonium persuliate 1 1 145 -do 2 1 240 3 1 234 5 1 202 3 1 225 3 1 260 4 1 232 3 1 217 0.2 1 232 10.0 1 272 Boric acid 10. 0 1 199 Sodium chloride 1. 0 1 215 Aluminum sulfato 6 1 218 Paraformaldehyde. 5. 0 1 200 Hydrochloric acid.- 0. 1 Pareformaldehyde- 5. 0 1 227 D0 Ammonium chloride 0. 1 Hydro] (deashed), D. B N one 0 0. 5 129 Do do 0 1 167 D0 Ammonium sulfate 3 0. 5 127 D0 do 3 1 221 Hydrol, D. B- N one 0 0. 5 87 Do o 0 1 158 0-. Ammonium sulfate 3 0. 5 113 130-- do 3 1 167 Alkali treat drol do 3 1 217 Dextrose 2nd greens, D, B do 5 1 269 Acid treated dextrose greens do 4 1 215 Corn siru D. B. 50 D. E do 7 1 classes, D. B None D 0. 5 89 D o 0 1 153 Ammonium sulfate 3 0. 6 156 -,do 3 1 158 None 0 0. 5 88 do 0 1 172 Ammonium sulfate 3 0. 5 243 .--do 3 1 238 N one 0 0. 5 68 d0 0 1 163 Ammonium sulfate 3 0. 5 134 do 3 1 211 None 0 0. 5 58 D do 0 1 135 D0 Ammonium sulfate 3 0. 5 113 D0 do 3 1 193 Table III VOLUME or GASES LIBERA'IED PER GRAM OF BAKED AFTER HEATING THE SAND FOR 1 MINUTE AT Gases Binders Used Adjunct Used Evolved V gilante reassessment masseuse??? 0.91% Dextrose hydrate (NHmso 1 These results show that the volume of gases liberated by baked cores prepared with cereal binder and dextrose hydrate blended with 9 percent of ammonium sulfate was more than 30 percent less than corresponding cores prepared without the adjunct.

Those skilled in the art of casting metals will recognize that this reduction in the volume of gases liberated by This is a continuation-in-part of application Serial No. 424,740, filed April 21, 1954, now abandoned.

I claim:

1. A process for producing a core for foundry use which comprises mixing parts of sand, 0.25 to 2 parts of cereal binder, 0.5 to 5 parts of sugar and from 0.002 to 0.15 part of adjunct per part of sugar, and sufiicient water to mull the resultant mixture, molding said mixture and baking it at a temperature of at least 350 K; said sugar-adjunct-binder containing from 1 to 20 parts of adjunct; all parts being on a weight basis; said adjunct being selected from the group consisting of hydrochloric acid; sodium chloride; a mixture consisting of 5 parts by weight of paraformaldehyde and 1 part by weight of ammonium chloride; boric acid; sulfuric acid, phosphoric acid, and salts which producesuch acids under said baking conditions.

2. A process for producing a core for foundry use which comprises mixing 100 parts of sand, 0.25 to 2 parts of cereal binder, 0.5 to 5 parts of sugar and from 0.002 to 0.15 part of ammonium sulfate per part of sugar, and suflicient water to mull the resultant mixture, molding said mixture and baking it at a temperature of at least 350' F.; all parts being on a weight basis.

3. A composition for bonding 100 parts of core sand consisting of 0.25 to 2 parts of cereal binder, 0.5 to 5 parts of sugar and from 0.002 to*0.15 part of adjunct per part of sugar, all parts on dry weight basis, and suflicient Water to mull the entire mixture, said adjunct beingselected from the group consisting of hydrochloric acid; sodium chloride; a mixture consisting paraformaldchyde and 1 part by .Might of ammonium chloride; boric acid; sulfuric acid, phosphoric acid, and salts which product such acids under baking at temperatures of at least 350 F.

4. A composition for bondingilOO parts of core sand consisting of 0.25 to 2 parts ofv cereal binder, 0.5 to 5 parts of sugar and from 0.002 to. 0.15 partof ammonium of parts by .Weightpof sulfate per partpf sugar, all parts on dry weight basis, and suificient water to mull the entire mixture.

"References Cited in thefileof patent NITED STATES PATENTS Nagel Mar. 31, 1925 Weidemann Nov. 22, 1931 Bauer Dcc. '12, 1933 Wallace c Sept. 24,1940

:FQREIGN PATENTS G reat Britain .Dec. 6,-1,939

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 2,875,073 February v24, 1959 Charles J, Gogek It is hereby certified that error appears in the above numbered patent requiring oorreotion end that the said Letters Patent should read as cor-=- reoted-below. v

in the grant, lines 2' and 3, for "assignor to Corn Products Refining tiompeny, of New York, N. L, a corporation of New Jersey," read aesignor to Corn Products Qompeny, a corporation of New Jersey, line 12, for Corn Produets Refining Company, its successors." reed Corn Products Company, ite successors g in the heading to the printed specification, linee 3, A. 5, for "eesign'or to Corn Products Refining Company, New i'ork, N Y a corporation of New Jersey" read an assignor to Corn Products @ompeny, a corporation of New Jersey column 6, lines 59 and 60, strike out "said euger=edjunet=binder containing from 1 to 20 parts of adjunct; h

Signed and sealed this 6th day of October 1959.

(SEAL) At'test:

KARL I. i. E t AXL ROBERT c. WATSON Attesting Officer Conmissioner of'Pmtents

Claims (1)

1. A PROCESS FOR PRODUCING A CORE FOR FOUNDRY USE WHICH COMPRISES MIXING 100 PARTS OF SAND, 0.25 TO 2 PARTS OF CEREAL BINDER, 0.5 TO 5 PARTS OF SUGAR AND FROM O.0002 TO 0.15 PART OF ADJUNCT PER PART OF SUGAR, AND SUFFICIENT WATER TO MULL THE RESULTANT MIXTURE, MOLDING SAID MIXTURE AND BAKING IT AT A TEMPERATURE OF AT LEAST 350* F; SAID SUGAR-ADJUNCT-BINDER CONTAINING FORM 1 TO 20 PARTS OF ADJUNCT; ALL PARTS BEING ON A WEIGHT BASIS; SAID ADJUNCT BEING SELECTED FROM THE GROUP CONSISTING OF HYDROCHLORIC ACID; SODIUM CHLORIDE; A MIXTURE CONSISTING OF 5 PARTS BY WEIGHT OF PARAFORMALDEHYDE AND 1 PART BY WEIGHT OF AMMONIUM CHLORIDE; BORIC ACID; SULFURIC ACID PHOSPHORIC ACID, AND SALTS WHICH PRODUCE SUCH ACIDS UNDER SAID BAKING CONDITIONS.