US1792580A - Method for producing light metal pistons running in cylinders of harder material - Google Patents

Description

CH K792 583- ME'TAL PIST HARDER MATER AT Bw NMO E s RWR 2. M

METHOD RUNNIN ii ab mwm.

ONS, IAL

FFE FOR PRODU G IN CYLINDE Filed A Patented Feb. 17, 1931 UNITED STATES PATENT OFFICE METHOD FOR PRODUCING LIGHT METAL PISTONS RUNNING IN CYLINDERS OF HARDER MATERIAL Application filed August 12, 1927. Serial No. 212,578.

' terial whether the separate particles are of greater or smaller size and the intervals in light metal are of like or different size. The actual running surfaces of the piston then form the harder superficial particles embedded in the light metal, whereby the surface in contact with the cylinder and consequently the friction, are reduced. These intermediate layers of light meta-l between the hard particles are also suitable for taking up lubricants, so that the easy sliding of the piston in the cylinder is obtainable.

Such hard particles distributed in the light metal may, for instance, be produced by adding in the alloy a greater or smaller quantity of substances which only dissolve partly or not at all in the light metal and again crystallize or separate out. It is also possible to alloy with the light metal substances which remain distributed in the liquid mass when poured in or introduced, or which are only partly dissolved, where, for instance, the quantity added exceeds the limit of dissolution and consequently produces separation. It has now been found that such pistons can only be used in practice if they are cast in such way that the axis of the piston, when cast, stands vertical. A mould as used for the above purpose is shown by way of example in Fig. 1 is a section on line AB of Fig. 2.

Fig. 2 is a section on line C.D of Fig. 1.

Fig. 3 is a section on line E-F of Fig. 2.

Fig. 4; is a section on line G-H of Fig. 3.

Fig. 5 is a section on line I-K of Fig. 3.

The casting mould a consists of metal, for instance iron, and has flanges b supporting the outer metallic cores 0. A central core (1 presses the two outer cores 0 against the .moulda and two other cores f are about in the centre of the mould. The casting holes 9 are shown in Fig. 3 and the various cross sections in Fig. 4. Fig.3 shows that the lateral limit lines are straight and the cross sections show that the casting hole is circular at the top and longitudinally rectangular below. For the practical application of the. method aluminium and silicon, for instance, are suitable. It has been found that the best cast is obtained by using perfectly pure metals. Alloys suitable in practice must have an addition of silicon exceeding 18%. For example, an addition of about 20-25% of silicon is very suitable. It is possible however to go up to 35% and event higher. For aluminium, in particular, the best application of the process is obtained if new aluminium only is used and not aluminium that has been remelted. To the aluminium is added metals or metalloids up to 5% of the total cast, in order to improve the certain,

other properties of the casting.

The metals or metalloids thus added are harder than aluminium and are such as are well known, a partial list including silver, copper, boron, zircon, beryllium, magnesium, titanium, vanadium, manganese, molybdenum and chrome- I claim 1. The method of casting articles such as pistons of light metal weight for engines, consisting in melting a light metal, embodying into said molten metal silicon constituting in quantity approximately 18% of the ultimate metal mixture, adding to aforesaid mixture particles of hard metals in amount approximately 5% of the ultimate mixture, pouring the molten mass into a vertical mold, and chilling the mass, whereby the hard metal particles are distributed over the surface of the casting.

2. The method of casting articles such as pistons of light weight metals for engines, said method consisting in melting aluminium, embodying to said molten aluminium silicon in'an amount constituting approximately 18% of the metal mixture, adding to aforesaid mass into a vertical mo d, an

mixture 2. quantity of particles of hard metals in amount approximately 5% of the ultimate metal mixture, ourin the molten chilling the mass whereby the hard metal particles are distributed over the surface of the casting.

In testimony whereof I afilx m signature.

FRITZ FEI-IRE BACH.

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