US1296593A - Piston-casting. - Google Patents

Description

' I. H. BAMBERG.

PISTON CASTING.

APPLICATION FILED: MAR. 8, 19!].

1,296,593. Patented Mar. 4,1919.

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l. H. BAMBERG.

PISTON CASTING.

APPLICATION FILED MAR. s. 1911.

1,296,593. Patented Mar. 4,1919.

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ATTORNEY.

JOSEPH H. BERG, OF TOLEDO, OHIO, ASSIGNOB TO THE ALUMINUM CASTINGS COMPANY, OF CLEVELAND, OHIO, A CORPORATION OF OHIO. 4

r'rs'ron-casrmc.

Specification of Letters Patent.

Patented Mar. 4 1919.

Original application filed. March 7, 1916, Serial No. 82,529. Divided and this application filed March 8, 1917. Serial No. 153,406.

T 0 all whom it may concern."

Be it known that I, Josnrn H. BAMBERG, a citizen of the United States, residing at Toledo, in the county of Lucas and State of Ohio, have invented certain new and useful Improvements in Piston-Castings, of which the following is a specification, reference being had therein to the accompanying drawing.

This invention relates to an internal combustion motor piston casting having internally projecting bosses, webs, ribs .and extensions, or either of them.

One object of my invention is to provlde a skirted piston cast of metal or metallic alloy of relatively low specific gravity and which is relatively non-porous, free from entrapped air and other gases and oxids and other foreign materials.

Another object of my invention is to pro-- vide a skirted piston cast of metal or metallic alloy of relatively low specific grav1ty and readily machinable to provide durable and efiicient bearing surfaces.

Another object of my invention is to provide a casting for a skirted piston for an internal combustion motor made from metal Another object of this invention is to provide a skirted piston casting made. of Va minimum volume of metallic alloy of relatively low specific gravity and 'high heat conductivity, which will not disintegrate nor undergo changes in its internal structure under ordinary usage in an lnternal combustion motor, and which will require a minimum amount of machining.

Another object of my invention is to provide a skirted piston casting made of a metallic alloy of relatively low specific gravity and high'heat conductivity and in which casting there is a relatively small amount of eutectic which substantially surrounds the excess substance in the casting.

Another object of my invention is to prov vide a skirted piston casting made of an alloy of relatively low specific gravity and high heat conductivity and in which casting there is a relatively small amount of eutectic disposed relative to the excess substance in such manner as to provide efiicient and durable machined bearing surfaces.

Another object of this invention is to rovide a piston casting of an aluminum a loy containing magnesium, tin and copper, having a structure relatively fine-grained, nonporous. and free from entrapped air and other gases and from oxids and other foreign materials.

Other objects of my invention will be obvious to one skilled in the art from the description of it hereinafter made.

The present application is a division of my. pending application, Serial No. 82,529, filed March 7, 1916, in which I have fully set forth and explained an apparatus and method suitable for the production of the piston casting to which the'present application relates.

Fig. 4 is a bottom plan view of the piston casting.

Fig. 5 is a side elevation of a mold adapted for the production of my improved piston castin part of the view being in section and t e core pins being shown removed.

Fig. 6 is a top plan view of the mold with the mold members separated and the cast ing attached to one of them.

The piston castlng, as to outward formation, has the usual piston head 1 and side wall 2 characteristic of the skirted pistons commonly employed in internal combustion engines. The side wall is formed with diametrically opposite inwardly projecting bosses 3, 3 which are cored out to receive a wrist-pin. The upper part of the casting, as shown, is provided with strengthening and heat dissipating ribs 4 and 5.

My improvements are not limited to the particular conformation of the casting shown but may be varied widely, as will be understood from thefollowing explanation of the matters which characterize my improvements.

The physical properties and internal structural characteristics which chiefly charac'terize my invention are the result of the constitutent materials employed in the casting and the manner in which the casting is formed. I will, accordingly, briefly describe a mold designed for the production of the castings and the manner in which such mold is used. For a full description and explanation of'the mold and the processof producing the castin by means of it, reference is had to my pen ing'application,

Ser. No. 82,529, above refe'rredto.

Referring to Figs. 5 and 6, the -mold comprises a base member a. and complementary members I; and a, movable on the base member or toward and from each other. (i indicates as an entirety the main core of the mold. This core is formed in a plurality of sections which are suitably recessed to form the bosses 3, 3, and ribs 4 and 5 on the interior of the piston. e, e are diametrically opposite core pins arranged to project into the mold cavity to form openings in or through the bosses 3, 3 of the piston casting.v These core pins are in the form of rods which are slidably mounted in alining openings of the mold members 6 and c.

The mold members I) and c are formed with complementary cavities or recesses b andc' which together form the mold gate. The gate thus formed, as will be observed from Fig. 6, is .disposed midway between the internal bosses 3, 3 of the piston casting. As is fully explained in my copending application referredto, I prefer to employ a gate constructed so that a liquid sea is formed which precludes the passage of air and gases into the mold cavity and also materially reduces splashing of metal within the gate during the pouring. Also the gate is preferably formed to communicate with the mold cavity at the bottom and at the.

top of the cavity and at intermediate points between the top and bottom.

The walls of the mold cavity are suitably coated or treated, in any well-known manner, to reduce as much as possible'agitation of the molten metal as it flows into contact therewith, and to insure proper setting of the metal within the mold cavity and a freeseparation of the castingfrom the mold. The inner walls of the cavity are also formed so as-to provide for venting of the cavity to assure the ready escape of air or gases as the molten metal flows i n..

Suitable means are provided for heating the walls of the mold members I), 0, and,

as the main core (1 and the core pins e, e are v separable from the members I), c, said parts al and e may readily be maintained at desired temperatures. As I have fully explained in my application, Ser. No. 82,529, the core pins are preferably kept at a temperature substantially'lower than the other parts of the mold cavity walls, and the temperature of the gate walls is kept higher than the other parts of members I), 0; and consequently when the molten metal, at a temperature hundreds of degrees above the temperature of the mold walls, is poured into the mold cavity it is subjected to a very'strong chilling action at points adjacent thecore pins 6, e and to a less marked but very substantial chilling action adjacent other parts of the cavity walls, while'the higher temperature of the gate walls insures the maintenance of molten metal in the gate until after freezing takes place in the mold cavity so that crystallization shrinkage'of the casting proper is obviated by the molten gate metal.

My invention, in its broader aspects, is A v.taining magnesium, tin and copper. While the proportions of these constitutents may be varied somewhat, I prefer an alloy havingapproxim'ately the following composition: Aluminum 95.5%, copper 2.5%, magnesium 1.5% and tin 0.5%.

In making a piston casting of metallic alloy such as last referred to the molten metal,

at a suitable temperature between'l380 F. and 1430 F., is poured by gravity through the gate and into the cavity of the mold.

The firstof the molten metal entering the mold cavity fills the'bottom thereof (this part of the cavity corresponding to the head of the piston) and thereafter the molten metal, as it enters the mold cavity, flows from the gate opening in opposite directions around the upright cylindrical parts of the cavity, the level of the metal in the cavity gradually rising until the cavity is filled. And, correspondingly, the metal of the castcomposition and suitably poured in the manner referred to, gives to the casting physical- 1 properties and internal structural char- 7 pin.

acteristics which are remarkable and, as I believe, greatly superior to any which have heretofore been obtained.

These superior properties and characteristics of my improved piston castings are: low specific gavity, high coeflicient of heat conductivity, relatively great strength, and a non-porous fine-grained structure free from impurities and from cavities due to crystallization shrinkage and with the eutectic substantially surrounding the excess material in such manner as to provide a durable and efficient bearing surface when the casting is machined. Furthermore the casting with an internal structure such as described, has very excellent machining qualities, while, both because 'of its structural character and the accuracy with which it is formed, little machining is required in producing the finished piston. Again the structure of the metal of the inner walls of the bosses 3, 3, resulting from the relatively quick setting of said metal, is particularly advantageous for cooperation with the wrist By reason of its fine grained, dense structure the casting, when machined, takes a high polish and has less tendency to collect carbon than does an iron piston. I have mentioned the bearing and wearing qualities of the castin and, in that connection may add that I ave been unable to note any disintegration in the structure of these castings after thousands of miles of severe service in relatively high speed motors of the internal combustion type. Furthermore, the internal physical structure of the casting characteristic of the above -mentioned relation of the'eutectic and excess substance is not changed by the working temperatures of the internal combustion motor to which said castings are subjected.

made of an alloy consisting predominantly substance as stated above, I believe it is desirable that it should not entirely surround and completely isolate said excess substance;

for, by avoiding such complete isolation of the excess substance, I believe greater tensile strength is secured.

To those skilled in the art many modifications of and widely differing embodiments and applications of my invention will suggest themselves, without departing from the spirit and scope thereof. My disclosures and the descriptions herein are purely illustrative and are not intended to to be in any sense limiting.

What' I claim is 1. As a new article of manufacture, an internal combustion motor piston casting of aluminum and containing magnesium, tin and copper, the casting having chilled walls and being fine grained and substantially free from porosity due to crystallization shrinkage.

2. As a new article of manufacture, an internal combustion motor piston casting made of an alloy consisting predominantly of aluminum'and containin other elements such'as magnesium, tin an copper in proportions to produce a relatively small quantity of eutectic in the casting after freezing, the casting having the said eutectic substantially surrounding the excess sub-' stance therein and having chilled walls.

As a new article of manufacture, an internal combustion motor piston casting made of an-alloy consisting predominantly of aluminum and containing other elements such as magnesium, tin and copper in proportions to produce a relatively small quantity of eutectic in the casting after freezing, the casting having the said eutectic substantially surrounding the excess subsubstantially freefrom porosity due to crystallization shrinkage.

4. As a new. article of manufacture, an internal combustion motor piston casting made of an alloy consisting predominantly of aluminum and containing other elements such as magnesium, tin and copper in proportions to produce a relatively small quantity of eutectic in the casting after freezing, the casting having the said eutectic 11 substantially surrounding the excess sub stance therein and being fine grained and substantially free from porosity due to crystallization shrinkage and entrapped air and other gases.

In testimony whereof, I hereunto aflix my signature;

JOSEPH- H. BAMBERG.

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