US2084129A - Crankshaft casting - Google Patents

Description

June 15, 1937. D, CAMPBELL 2,084,129

I CRANKSHAFT CASTING Filed Dec. 9, 1935 2 Sheets-Sheet 1 I l I I a 7g8q/ 14 2 4 4 INVENTOR 204 040 16240111514 ATTORNE June 15, 1937. CAMPBELL 2,084,129

CRANKSHAFT CASTING Filed Dec. 9, 1935 2 Sheets-Sheet 2 INVENTOR fiamzo Jlbmuu ATTORNEY Patented June 15, 1937 Ui'i'ED STATES CRANKSHAFT CASTING Donald J. Campbell,

Spring "Lake Township,

Uttawa County, Mich, assignor to Campbell, Wyan't & Cannon Foundry Company, Muskegon Heights, Mich, a. corporation of Michigan.

Application December 9, 1935,Serial No. 53,548

1 Claim.

This invention relates to the production of cast crankshafts primarily for use in internal combustion engines.

I have accomplished the casting of crankshafts for internal combustion use and have successfully attained economical casting thereof. The problem of casting crankshafts, one after the other from the same patterns, and having the product uniform, has been a difficult one. In the course of experimentation I have found that one of the most satisfactory methods of casting crankshafts is that disclosed in my Patent No. 2,014,224, issued September 10, 1935. There a mold is provided having a mold cavity in conformity to the crankshaft to be cast, and with a feeder cavity at one end of the crankshaft mold cavity joining therewith. The molten metal is poured into the mold cavity with the mold in a horizontal position, and. after the mold and feeder cavities are filled the mold is turned to a 20 vertical position with the feeder cavity, filled with molten ferrous metal, at the upper end of the mold. In addition, the heavy flank portions of the crankshaft have other feeder cavities provided which are filled with the molten metal when the metal is poured into the mold, which feeder cavities are disposed above the planes of the flanks to feed said flanks when the mold is turned to a vertical position. All of this is fully disclosed in the patent referred to, designed for the purpose of compensating for the shrinkage which takes place when the molten metal cools.

. The metal, which is used in casting crankshafts, has a relatively low carbon content, which 95 may not exceed one and one-half percent. The molten metal, when it solidifies, has more or less shrinkage in accordance with the carbon content therein. A cast iron havinga high carbon content shrinks less than one having a low carbon content for the reason that when the metal is molten, the free carbon is in solution in the molten metal, but when solidification takes place the free carbon separates out from. the iron thereby occupying space which was not previous- 45 ly occupied by the carbon in solution, whereby the amount of shrinkage is considerably greater with cast iron having a low carbon content than with one having a high carbon content.

The problems involved because of shrinkage are 50 of greater moment in the casting of crankshafts than in the casting of many articles which do not require a cast ferrous metal of the same quali ties and wherein the free carbon content is greater than used in casting crankshafts.

The shrinkage, particularly with respect to the heavy'flanks of a crankshaft and at one end thereof, isfreadily taken care of in accordance with the method of molding disclosed inmy Patent No. 2,014,224. The intermediate crank portions of the crankshaft between such flanks still present a problem of shrinkage which it is the Object in the present invention to solve in a sim ple and economical manner, whereby the method of molding shown in my prior patent, is availed of and the shrinkage at all parts of the casting is.

taken care of, thereby producing cast crankshafts economically, free from' dirt and'imperfections and free from shrinkage, .draws, sinks, or cracks and wherein regular and usual methods of foundry practice are followed, utilizing the same type of labor for all parts of the molding operations, so that no especially skilled labor other thanthat which is. ordinarily used foundries is required.

All of these features of advantage of my invention will appear and be understood from the following description, taken in connection with the accompanying drawings, in which,

Fig. 1 is an underplan view of the cope portion of the mold which is used in casting crankshafts.

Fig.2 is'a plan view of the drag-portion of the mold. r

Figs. 3 and 4 are transverse vertical sections substantially on the planes of lines 3-42 and 4- of Fig. 2 looking in the directions indicated.

Figs. 5 and 6 are, respectively, a perspective and a plan view of ametal chill or insert used in conjunction with the counterweight partof the crankshaft casting. I

Figs. 7, .8. and 9 are elevation views of insert chills which are used at one end bearing,'at intermediate shaft bearings and at the wrist pin portions of the crankshaft, respectively, and

Fig. 10 is an elevation of a crankshaft which is produced.

Like reference characters refer to like parts in the different figures of the drawings.

The cope and drag flasks l and 2 are of usual construction adapted to be filled with molding sand for the production of a mold for the crankshaft. As illustrated, two of the crankshafts are to be simultaneously produced and the sand 3 of the mold, together with various cores, which are indicated at 4, are used in the production of the mold toprovide mold cavities corresponding in shape to the crankshaft casting which is to be produced.

The crankshaft shown in Fig. 10 has opposite end bearings 5 and 6 with other intermediate bearings in axial alinement therewith, crank bearings or metal inserts.

l5 joining with one end of each of the mold cavi' ties, with an intermediate chamber. t6, intdwhich the metal is poured through the sprue H. The molten metal passes through. a skim gate I8 and: runner gates I9, thence into the feeder cavities l5,

and therefrom to the mold cavities for the crank:.

shafts. There is also provided in the mold between the two mold cavities for the crankshafts,

feeder cavities 20 which connect with both the mold cavities, and which preferably are dividedinto two parts by thin slab cores 2| (see Fig. 2).

These additional feeder cavities connect with the cavities which produce the heavier cranks 13 of the mold and are filled with molten metal simultaneously with all other parts of the moldcavities, whereby when the pouring operation has been completed and the mold is turned to a vertical position, with the feeder cavities l5 at the upper end of the mold the feeder cavities I4 will also, by

gravity, feed molten metal to the cranks t3. As

thus far described, the mold and'its operation are substantially identical with what is set forth in my Patent No. 2,014,224.

In the present invention, for-the end bearing 5 of the crankshaft opposite the end of the shaft adjacent which the feeder cavity I5 islocated, a cylindrical member 22' is located in the mold cavity 5a. and is carried by the adjacent core 4 so as to lie centrally of themold cavity 5a, whereby the molten metal. will surround the member 22 when the casting is poured. Similarly, centrally through each of. the axial bearing portions 1, a member of the form shown at 23.. in Fig. 8 is located lengthwise of and at the axial centers of each of the cavities la. In the crank pin cavities 8a and extending through the cavity Ma; forthe balancing or counterweight 14,. is an elongated metal member of circular cross section as indicated at 24 having a middle bowed, section-25'. Likewise, in the counterweight cavity Ha. there-is mounted a metal member 26 spacedfrom the. previously described bowed section 25 and also spaced from the walls of the cavity. These members: 22", 23, 24 and 26 are of metalandtmay be called'chi'lls They may betermedchills, inasmuch as the molten metal coming to them is rapidly cooled when it surrounds the same, and

they are in effect metal inserts because the molten metal surrounding the same and solidifying fuses thereon firmly, retaining such inserts in the completed cast crankshaft.

The effect of the metal chills or'inserts is" that when the molten metal strikes the walls of the mold cavity and also the surfaces of the metal inserts it solidifies and cools first at such points,

providing comparatively thin portions between such metal inserts and adjacent walls of the.

cavities for the metal, and changing entirely the character of the solidification of the metal. When such inserts are not used, the molten metal first solidifies adjacent the walls of the mold cavities and last at the central portions, thereby causing shrinkage, draws, sinks, or checks. But with the central portions of these cavities, solidifying instantly around the various chills or inserts, the solidification of the metal is much more rapid and there is no detrimental shrinking,

drawing orsinking of the metal as may occur where the solidification is from the outside to the center. The solidification of the metal with my invention, both from the outside inward and from the center outward effects elimination of shrinkage draws, cracks or sinks, and insures that the intermediate portion of the crankshaft and also the end bearing 5, farthest away from the feeder cavities l5, shall be of a uniform and substantially perfect character. It is, of course, to be understood that the. various inserts 22., 23, 24 and 26 are properly supported in the mold so as to extend lengthwise of the cavities and substantially at the center portions thereof. -The counterweight I4 has a comparatively large cross section insert or chill 26 because of the body of the metal involved. The insert 26 can be used with.

the counterweight, upon which there is no substantial strain, and in the finished casting such insert or chill is retained in the counterweight as a part thereof.

The invention perfects the method of casting described in my earlier Patent No. 2,014,224, and insures against defects because of shrinkage at the intermediate portions of the crankshaft. The bearing at 6a does not require the metal insert asshrinkage therein istaken care of by the molten metal. in the feeder cavity at IS. The same is. true with regard to the cranks l3 and. the, bearings IOadjacent thereto; while the fiat cranks l I and I2 are of. sufficiently narrow width that shrinkage defects of any substantial degree do not occur.

Having thus fully described my invention what I desire to claim and secure by Letters Patent is:

The method of casting a crankshaft having a thickened portion and a relatively thin portion which consists in providing a mold cavity in. which to cast the said shaft, further providing a cojoining feeder cavity adjacent-the thickened portion of the shaft and also providing a core formed of metal having the characteristics of melting at substantially the same temperature as the metal from which the crankshaft is cast and also of absorbing a material quantity of heat, locating said mold in asubstantially horizontal position and pouring a ferrous molten metalinto said mold cavity to fill the same and more or less fill the feeder cavity, said molten metal flowing past the core, said core being located in the thickened portion of the crankshaft mold, and then changing the position of the mold to, substantially ver-' tical position with the molten metal in the feeder cavity tending to fiow into the adjacent enlarged portion of the mold during the cooling thereof, said molten metal changing its relative position with respect to the core during the changing ofv the position of the mold. v

DONALD J. CAMPBELL.

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