US2425502A - Abrasive wheel - Google Patents

Description

Patented Aug. 12, 1947 ABRASIVE WHEEL Cecil E. Wilson,

Baton Rouge, La., assignor to Independent Grinding Wheel Company,

Inc.,

New Orleans, La., a corporation of Louisiana No Drawing. Application June 26, 1946 Serial No. 679,590

Claims.

This invention relates to abrading devices, more particularly abrasive and cutting wheels, and is an improvement on the invention of my Patent No. 1,997,957, issued April 16, 1935.

The principal object of this invention is to produce abrading devices, such as abrasive and cutting wheels, which grind equally well both low and high tensile strength materials. Hence, a purpose is to provide an all-purpose abrading device, such as a wheel, which successfully cuts all standard metals, such as steel, iron, cast iron, malleable iron, bronze, brass, aluminum, a large number of alloys of said metals, and, in addition, such non-metallic substances as tile, marble, granite, variousother stones, glass and brick.

Another object of this invention is to embrace in one abrasive wheel the qualities and characteristics of two or more abrasive wheels which are designed for particular cutting or grinding operations. Hence, it is an object to do away with the need of purchasing and keeping numerous special cutting wheels, such as a special wheel for high-speed steel, a special wheel for soft and stainless steel, a special wheel for brass, bronze and cast iron, a special wheel for aluminum and a special wheel for some other metal or alloy.

Another object is to provide a cutting wheel which is substantially free from cracks or checks which weaken the texture of the wheel.

A still further object is toprovide a simple and,

economical method of manufacturing abrasive and grinding wheels.

A still further object is to combine the two abrasive grains, silicon carbide and aluminum oxide (A1203) in an abrasive wheel while preserving the initial cutting properties of each type grain.

Other objects and advantages of this invention will become apparent during the course of the following description.

Silicon carbide grain in various sizes is used as a standard component in making grinding wheels designated for cutting metals of low tensile strength as well as other materials of low tensile strength. Likewise aluminum oxide grain is conventionally employed in making abrasive wheels designated for cutting metals of high tensile strength.

For the past thirty years companies manufacturing grinding and cutting wheels have unsuccessfully tried to produce such wheels which would grind equally well both low as well as high tensile strength materials such as steel, brass, bronze, aluminum, cast iron, malleable iron, alloys thereof, and glass, tile brick, granite, marble and other mineral substances. They have failed because of the inherent nature of the bonds resulting in the oven-baked or vitrified process and the chemical characteristics of the two cutting grits or abrasive grains. A chemical reaction takes place, negativing the initial physical characteristics of the two kinds of grains. One of the abrasive grains has an acid base and under the heat in the vitrified or other oven-baked processes, when the two grains are combined in one wheel and excessive heat applied, this changes the other abrasive grain. The cutting qualities of the other abrasive grain are changed. In addition the acid-base grain undergoes a change itself.

Moreover, a cutting wheel produced with heat when the two kinds of grains are combined cracks very appreciably or checks throughout. This. weakens the texture of the wheel to a degree of danger when the wheel is operated at high. speeds.

As a result of extensive research directed to the production of grinding wheels which will cut low strength material and high strength material equally well, applicant has discovered a combination of components and a process which give an all-purpose grinding wheel.

The composition for preparing molded abrasives according to this invention. broadly comprises an intimate mixture of the two abrasive grains, silicon carbide and aluminum oxide, calcined magnesite, ferrous chloride, magnesium chloride and water. Conventional coloring material is usually added but this is not necessary. This composition, although it has several constituents in common with the composition of my Patent No. 1,997,957, is necessary to produce an abrasive and cutting product of manifold. performance, the formula of my patent not yielding an all-purpose cutting and grinding product.

The process according to this invention broadly comprises preparing a moldable mixture of abrasive grains, especially aluminum oxide and silicon carbide abrasive grains, calcined magnesite, ferrous chloride, magnesium chloride and water, introducing such mixture into a mold of the desired shape and permitting it to remain in such mold until the mixture sets sufiiciently to permit handling, removing from the mold, treating the molded product with a solution of magnesium sulfate and hydrochloric acid, as by dipping, removing it, and permitting the resulting product to set to complete hardness. The molded product is not dried or cured by a vitrifying process, such as firing at high temperature in a kiln. In the practice of this invention molds of various sizes,

required in some instances.

shapes and construction may be employed but a wheel-forming mold is preferred.

Numerous ratios of the quantity of silicon carbide to aluminum oxide can be used in making the all-purpose cutting wheel. To illustrate, fifty per cent. of each can be employed; sixty per cent. of the former, forty per cent. of the latterjforty per cent. of the former, sixty per cent. of the latter; and various other ratios, as desired. These combinations'can be made in any size of commercial grain of both kinds of such materials.

In preparing the mixture to be molded, it is preferred to employ a Inim'ng container with a round bottom and provided with an efiicient stirring device. Aluminum oxide (A1203) in crystalline form and crystalline silicon carbide are first introduced into this mixing container. Calcined magnesite is then added to the mass in the mixing container. This product is commercially available in the form of a powder almost as fine as talcum powder and this commercial product is entirely satisfactory. Of course, should it be desired, the equivalent of the calcined magnesite may be obtained from other sources or produced in the laboratory. The calcined magnesite or its equivalent is thoroughly mixed with the abrasive grams to secure a substantially uniform mixture.

Ferrous chloride, preferably in aqueous solution. is then added to the dry ingredients and.

the mass stirred to effect complete mixing. Magnesium chloride, preferably in solution, is then added to this mixture with stirring, While it is advantageous to add the ferrous chloride solution. and the magnesium chloride solution reasonably slowly while agitating the mass, this is not essential so long as a uniform mixture is secured. If desired, the entire amount of the ferrous chloride solution can be added at one time and then the entire amount of magnesium chloride solution added at one time, after which the mass is stirred thoroughly for several minutes to effect complete mixing.

After the mass has been thoroughly mixed, with or without color being added to the mixture, it is then poured into a suitable mold. The mold is shaken several times during the addition of the mass in order to make certain that the mold is completely filled with the mass and air spaces avoided. After the mold has been filled it is advisable to pass a straight-edge scraper across the upper edges of the mold members to remove any excess of material in the mold and provide a flat surface'for the material in the mold.

The mass is permitted tostand in the mold until it has set to a suflicient degree to permit the removal of the mold dling' of the product without breaking or distortion. Ordinarily, this condition will be reached after the mass has been in the mold for about. 2 to 3 hours, although a longer period may be However, a skilled operator can readily determine after a few experiments the exact time for mass from the mold.

After the mass has been allowed to set in the mold for the required period, the mold members are removed and the center core is also removed.

The partially hardened molded material is then immersed for a short period in an aqueous solution of magnesium sulfate and hydrochloric acid. Themolded material after removal from this solution is permitted to set on a flat surface for about 2 to 3 hours, During this period the wheel becomes relatively hot but gradually cools off and members and the hen the removal of the magnesium sulfate solution to is speed-tested for use reaches room temperature at the completion of the setting. Thereafter the wheel is ready to bebabbitted and set in conventional mounting for grams, of ferrous chloride are added to the mixture, preferably in the form of a concentrated or saturated aqueous solution. From 8 to 14 liquid ounces, and preferably fourteen liquid ounces, of an aqueous solution 'of magnesium chloride of from 19 to 24 Baum, andlpreferably 22 Baum, are added to the above mixture. About one-half ounce of conventional color is then added. The resulting mass is tho-roughly stirred for several minutes, say five minutes', to produce a uniform mass having the approximate oonsistency of dough. This moldable mass is then introduced into a wheel-forming mold, where it is hours, say two hours.

After the mass has set to at least partial hard I ness in the mold, the mold members are removed, and the resulting wheel is then immersed for from 2 to 8 minutes, and preferably about 5 minutes, in an aqueous treating solution containing magnesium sulfate and hydrochloric acid. This solution is preferably prepared by adding technical hydrochloric water. For. each quart of water used'in preparing the olution, I preferably employ an equal volume of technical hydrochloric acid (acid muriatic) of about 18 Baum and about eight liquid ounces of magne'sium sulfate solution of approximately 30 Bau'm. Of course, the treating solution may be otherwise prepared and other relatively strong hydrochloric acid solutions of magnesium sulfate may be employed. However, I have found that optimum results are obtained with a treating solution as described above. 7

After the Wheel is immersed in the treating solution for the desired period, it is removed, and placed'on a drying rack for drying, and cur ing. The drying and curing ordinarily requires from two to three'hours, after which the wheel is babbitted, blotters are applied and the wheel on a grinder.

The following is a specific example of the process used in preparing a 7" x 1 all-purpose grinding wheel. V

One pound of silicon carbide grain .of selected size is mixed with one and one-half pounds of. aluminum oxide grain of similar size. ounces of calcined mixture are. then added and mixed with these grains.

is added. The resulting mixture is thoroughly mixedfor about five minutes. The resulting mass then placed in a wheel-forming mold,

where the mass is permitted toset for about. two or two and one-half hours practice of thisinvention, a

grains being in permitted to set for several J acid and a strong Fourteen V Fourteen liquid ounces of magnesium chloride solution of 22 Baum The resulting product is removed from the mold and immersed in a solution prepared from eight liquid ounces of magnesium sulfate solution of 30 Baum, one quart technical hydrochloric acid (18 Baurn) and one quart of pure water. After about minutes, the wheel is removed from the solution and dried and cured on a rack for from two to three hours. The wheel is then babbitted, blotters are applied and the wheel speed-tested.

As will be apparent, wheels prepared by the present process may be rapidly, simply and economically produced. Moreover, my abrasive wheels are highly advantageous in comparison with abrasive wheels heretofore produced. By my process, wheels are produced which are substantially completely free from cracks or checks. Moreover, the initial physical characteristics of the two kinds of grains employed are not changed as in other processes, such as the vitrified process. As will be apparent, no heat is artificially applied in my process and the chemical reaction or reactions which detrimentally aifects or kills the cutting qualities of the grains in other processe does not take place, with the result that the cutting characteristics possessed by each of the grains employed are preserved in the grinding wheel produced by my process.

While I have described in detail the preferred practice of my process and the preferred compositions for use in connection therewith, it will be understood that the details of procedure of the process and the composition of the mixture for preparing the molded product, as well as the composition of the treating solution described above, may be variously modified without departing from the spirit of the invention or the scope of the subjoined claims.

I claim:

1. A process of the character described which comprises preparing a moldable mixture of abrasive grains, calcined magnesite, ferrous chloride, magnesium chloride and water, molding said composition in a desired shape, and treating the molded composition with an aqueous solution of magnesium sulfate and hydrochloric acid.

2. A process of preparing a molded abrasive product of manifold performance which comprises preparing a mixture of silicon carbide abrasive grains, aluminum oxide abrasive grains, calcined magnesite, ferrous chloride, magnesium chloride and water, intimately mixing the resulting mass, introducing the mass into a mold, permitting the mass to set to at least partial hardness in said mold, removing the resulting product from the mold, and treating such product with an aqueous solution'of magnesium sulfate and hydrochloric acid.

3. A process of preparing abrasive and cutting product with an aqueous solution of magnesium sulfate and hydrochloric acid, and permitting the resultin product to set to complete hardness,

4. A process of preparing abrasive and cutting devices of manifold performance which comprises preparing an intimate moldable mixture of silicon carbide abrasive grains, aluminum oxide abrasive grains, calcined magnesite, ferrous chloride solution and magnesium chloride solution, introduc ing the resulting mixture into a mold, permitting the mass to set to partial hardness in said mold, removing the resulting product from the mold, and immersing the product in an aqueous solution of magnesium sulfate and hydrochloric acid.

5. A process of preparing abrasive and cutting devices of manifold performance which comprises preparing an intimate moldable mixture of silicon carbide abrasive grains, aluminum oxide abrasive grains, calcined magnesite, ferrous chloride and magnesium chloride solutions, introducing the resulting mixture into a mold, permitting the mass to set to partial hardness in said mold, removing the resulting product from the mold, dipping such product in an aqueous solution of magnesium sulfate and hydrochloric acid, removing the thus treated product from such solution, and permit ting the resulting product to set to complete hardness.

CECIL E. WILSON.

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

UNITED STATES PATENTS