US1339096A - Process of casting iron screen-plates for steel grids - Google Patents

Description

D. BROWN.

PROCESS OF CASTING IRON SCREEN PLATES FOR STEEL GRIDS.

' APPLICATION FILED DEC. 14. 1917.

Patented May 4, 1920.

2 SHEETS-SHEET I.

ftverli' 0 7 ,Davis flrowv-a D. BROWN. PROCESS OF CASTING IRON SCREEN PLATES FOR STEEL GRIDS.

APPLIC A TION FILED DEC 14. I917- Patented May 4, 1920.

2 SHEETS-SHEET 2- DAVIS BROWN, or BUCYBUS, onr ns'sren-on TOTHE AMnnIcAn'oLAY MACHINERY GOM PANY, A CORPORATION OF OHIO. v

PROCESS CASTING IRON SCREEN-PLATES STEEL GRIDS Specification of Letters Patent.

Patented. May 4, 1920.

Application filed December 14, 1917. Serial- 110. 207,043.

To all whom it may concern.

Be it known that .I, DAVIS BROWN, a citizen of the United States, and resident of Bucyrus, in the county of Crawford and State of Ohio, have invented an Improvement in Processes of Casting Iron Screen- Plates for Steel Grids, of which the following description, in connection withpthe accompanying drawings, is a specification, l ke letters on the drawings representing l1ke parts.

My present invention is an improved dry pan, for use in pulverizing and grinding clay and similar substances, and the lnvention more particularly relates to an 1mproved construction of screen plates therefor, and to a novel method of maklng the same.

974,818, issued November 8, 1910, where an efficient type of this kind of machlne is shown, the screen plates utilized have been in cross section and producing an exceedingly large surface area of the cast 1r0n in proportion to the slots through which the ground material is screened. These bars or grids, when made of cast iron,'must also be relatively short in length'to avoid liability of breakage.

expense and labor involved have been so great that this also has been objectionable. The use of such steel grids, heretofore, has

required the fitting in the rolled steel grids,

in a cast iron framework, but. because of the difliculty, time and prohibitive cost, this method has never been commercially practicable. l

My present invention enables a screen to be made of steel bars in an economical and practicable manner, and by a novel process of manufacture, whereby t e diflicultles and In dry pans, such for example. as. that shown in the patent to R. G. Penfield, No.

Attempts have been made to utilize steel grids or bars, but the expense heretofore met with are entirely eliminated. In carrying out my present inventionI provide the usual. pattern for easting the frame of the screen around the outer side,'but I so arrange an intermediate section for supporting the'inner ends of the grids as to form same first in relatively thin metal portions capable of springing during the cooling of the'frame' without danger of distorting the heavier outside rims. I accomplish this by first forming'the middle section or partition in a usual manner and then fitting a core through the middle section of'the mold for'this middle partition, applying the steel bars throughout the mold in desired proximity with their outer ends in line to fit within the casting and the inner ends. within one of the relatively thin middle partitions cast by the application of the core through the middle mold as above explained.v The iron is then'cast to form the frame, firmlyengaging and holding the respective ends of the steel rids,'and perpermitted to cool. During t is cooling, the contraction of the frame may draw the inner thin partitions somewhat, but said inner partitions'are'so formed as to spring and permit this contraction. Thereafter the middle section is again fittedin a mold, and the space from which the core has been removed isfil'led 111 p with molten iron, as a separate casting. referably the second casting is made to dovetail with or interlock about the two thin members which were originally made for the central partitions. This process thusrproduces an improved screen, with an iron frame and steel grids or bars, permitting the same to be made in a feasible, practicable and commercialimanner at a minimum of cost, automatically taking care of the normal tendency of the metal to shrink or contract when cooling down in a mold, and furthermore preventing the steel bars from buckling when cooling. I believe that this process is a distinct novelty in the art, and therefore wish to claim the same broadly.

- Referringto the drawings illustrating a preferred embodiment of the invention,

Fig. 1 is a view partly in cross section of a dry pan; 1

Fig. 2 is an enlarged view of one of the screen plates;

Fig. 3 is a cross-sectional view on the line 33 of Fig. 2;

Figs. 4 and 5 .and 6 are detailed views of the connections between the steel grid bars and the cast iron frame.

I have shown in the drawings, for illustrative purposes, the type of dry pan such as that illustrated in Patent 9%,818, above referred to, wherein the dry pan is built upon the foundation or framework 1, hav ing suitable side frames 2, a central drive shaft 3, suitable mechanism for supporting the mullers 4, the main grinding base or hub 5, radial carrying flanges (3, and cylindrical rim 7 carrying the screen plates 8, arranged in segmental sections around the revolving pan. y

Each screen section, as illustrated in Fig. 2, comprises a frame with the inner rim portions 10 and outer rim portions 11 in concentric arcs and of a size suitable for the diameter of dry pan in which they are to be employed. This section is further formed with radial frame portions 12 and 13, built of cast iron. The radial frame portions 12 and 13 are each formed as shown in Fig. 1 with a dove-tailed recess as indicated at 1 1 to receive the correspondingly shaped end 15 of a steel grid bar 16. Preferably these recesses 14 are made in groups of three or four, four such being shown at 17, 17, 17, 17, in the drawings. This permits a set of four grid bars of the same length to be interchangeably fitted at appropriate sections throughout the screen.

The dovetailing arrangement of the steel grid bars in the outer cast iron frame sections 12 and 13 as just described, is readily accomplished by fitting the bars therein be fore the central partition 20 is formed. As shown in Fig. 5, the inner ends of the steel bars 16 are similarly dovetailed and fitted into a thin spacing and carrying member 21 and 21, which members 21 are appropriately'spaced from each other to permit the subsequent pouring of the iron to form the rest of the middle partition 20. I prefer to formthese thin divisional walls of irregular shape, such as, for example on the curved lines 22, 22, in order to provide an interlock-- ing when the rest of this middle partition member, via, the member 20, is cast therein.

The pattern is molded in the sand in the usual way, then the pattern is withdrawn and a dry sand core, substantially of the form shown at 20, Fig. 2, and the steel bars, 1.6,are placed'in the sand in their proper places. The mold is then closed and the cast iron poured around the bars 16 and the core in the place of the member 20. After cooling the casting is removed from the sand and cleaned. The core being cleaned out leaves a space between the two division walls 21. In cooling, the cast iron frame shrinks closing in on the bars and forces them to ward the center and the center division walls 21, which being purposely lighter and weaker than the other and outer walls of the frame, will spring or maybe break away from the main frame at the junction points and this is what prevents buckling of the bars or weakening of the main frame when it contracts in cooling. The space between the two light division walls 21 permits them to spring toward or from each other and relieve the bars and the main frame of the strains caused by the shrinkage of the cast frame on cooling down from the molten state. The bars are not sub-- ject to this shrinkage. After cooling down and cleaning, th frame is 'again placed in the sand and the space between the two light center walls and additional space below these light partition walls is poured filling the vacant space between them and forming a permanent support beneath them, interlocking, solidifying, and strengthening the center partition '20, 21 and 21 being a substantially solid member. My novel process of thus combining steel grid bars with the cast iron frame, also secures the advantages of a simple and economical construction, and presents a screen plate with the desired increase in area of openings and with steel grids which. will outlast the cast iron many times over.

Fig. 6 illustrates, in cross section on the line 66 of Fig. 2, the present arrangement for the reinforcing poured metal 20 of themiddle partition, where the same interlocks and bears upon the frame 10.

lVhile I have described my novel method of construction as for use principally in making screen plates with the outside frame of cast iron and the grid bars of steel, and while I wish to-claim the resulting screen plates as a new article of manufacture, it will be appreciated that the method is not limited to the manufacture of screen'plates. I believe that my novel method of manufacture, which consists in the provision of relatively thin members, such as the partition members 21, capable of spring during contracting or cooling, is a distinct novelty in the art wherein the problems incident to casting metals,especially using different metals are present. I therefore wish to claim this method broadly, relying upon the illustration herein as a specific manner of carrying out this method, without, however, limiting the same to such screen plates.

hly invention is further described and defined in the form of claims as follows:

1. The improved method of manufacturing articles from cast metal, which consists in forming a mold for the resulting casting, coring a portion of the. mold form, in a manner to leave an interlocking or dovetailed contour, casting the metal therein, then allowing said metal to cool and contract and then subsequently casting metal in the first'cored portion, and causing'the second casting of metal to interlock with the cooperating contour therefor of the first cored portion.

2. The improved method of casting an article having a cast iron outer frame and steel bars extending from one portion of said frame to the other, which consists in forming a mold, coring one portion of the mold, applying the bars from one frame section to said cored portion, casting the iron therein, allowing the casting to cool and contract, said cored section being relatively thin, to spring or yield during cooling, whereby the main portion of the frame will be relieved from shrinking strains during said cooling.

3. The improved method of casting an article having a cast iron outer frame and steel bars extending from one portion of said frame to the other, which consists in forming a mold, coring one portion of the mold, applying the bars from one frame section to said cored portion, casting the iron therein, allowing the casting to cool and contract, said cored section being relatively thin, to spring or yield during cooling, and then casting a strengthening member adjacent the cored portion of the frame.

4%.. The improved method of casting an iron screen plate with steel grid bars having a central partition to receive the inner ends of said bars, which consists in forming a mold, placing the steel bars in the mold with their outer ends in position in the frame mold, and their inner ends respectively in a relatively narrow portion of the inner mold, coring said inner frame mold between the ends of the grid bars, casting the frame, then permitting said frame to cool, and then casting a reinforcing member for the middle partition substantially in place of the originally cored portion.

5. The improved method of casting an iron screen plate with steel grid bars having a central partition to receive the inner ends of said bars, which consists in forming a mold, placing the steel bars in the mold with their outer ends in position in the frame mold, and their inner ends respec tively in a relatively narrow portion of the inner mold, coring said inner frame mold between the ends of the grid bars, casting the frame, then permitting said frame to cool, and then casting a reinforcing member having an interhicking contour with said middle partition substantially in place of the originally cored portion.

In testimony whereof, I have signed my name to this specification, in the presence of two subscribing witnesses.

DAVIS BROlVN'.

lVitnesses H. L. TIARMON, A. B. BRADSTOOK.

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