US2008854A - Means for producing hardened cast iron valve tappets - Google Patents

Description

J. L. DOSTAL 2,008,854

MEANS FOR PRODUCING HARDENED CAST IRON VALVE TAPPETS July 23, 1935.

3 Sheets-Sheet 1 7 Original Filed Sept. 28, 1929 Jose-PH L. DUSTFIL lNVENTOR ATTORNEY July 23, 1935. J. L. DOSTAL 2,008,854

MEANS FOR PRODUCING HARDENED CAST IRON VALVE TAPPETS Original Filed Sept. 28, 1929 s Sheets-Sheet 2 LET INVENTOR BY W ATTORNEY July 23, 1935.

J. L. 'DOSTAL MEANS FOR PRODUCING HARDENED CAST IRON VALVE TAPPETS Original. Filed Sept. 28, 1929 3 Sheets-Sheet 3 Elm-5.5-

INVENTOR W ATTORNEY Patented July 23, 1935 UNITED STATES PATENT OFFICE MEANS FoR PRODUCING HARDENED CAST IRON VALVE TAPPETS Michigan Application September 28, 1929, Serial No. 395,949 Renewed July 15, 1932 1 Claim.

This invention relates to an improved method of making cast iron tappets for use in internal combustion engines and means therefor.

The object of this invention is to produce a cast iron tappet having a hard face and a stem which is not so hard but that the extreme end can be drilled and tapped for the tappet adjusting screw.

In the drawings:-

Figure 1 shows in elevation a view of the valve tappet casting.

Figure 2 shows in elevation the simplest form of mold in which it is possible to produce these tappets.

Figure 3 shows a. cross section elevation on plane 3--3 of Figure 2. a

Figure'4 shows in elevation a more elaborate mold which has been found satisfactory when large quantities of valve tappets are required.

Figure 5 is a cross section elevation on the plane 5-5 of Figure 4.

Figure 6 is a plane view looking down on Figure 5.

Figure 7 shows a portion of the mold shown in Figure 4.

In Figures 1, 2 and 3, A is the valve tappet stem, B is the hardened face of the valve tappet, E is the sprue. In Figure 2, C is the permanent metallic mold having a number of mold cavities DD. EE are the gates into which the metal is poured. K are the cavities below the cavity D in which the mushroom heads of the tappets are formed. F is a thermo couple connected through leads G, to an instrument H which records the temperature of the mold at a point as near as possible to the point where the face B of the valve tappet A solidifies.

The diameter of the valve stem A is approximately and the mean thickness of the valve tappet is in the head.

The surface of the mold cavity is coated with a thin adherent heat insulating refractory coating as described in the Meloche Patent No. 1,453,- 593. This refractory coating isalso covered with a lamp black coating, as described in Patent No. 1,492,694. At K the face is unprotected except by the lamp black coating, the reason for this is that at this point the head solidifies, and there- .fore the maximum temperature drop is desired -at this point between the temperature of the molten iron and the temperature of the face of the mold, so that the rate of cooling shall be sufliciently rapid so that the face of the casting hardens on solidifying, that is to say that a considerable quantity of carbon is retained in solution.

Figs. 4, 5, 6 and 7, show an improved permanent mold in which each half is formed of three metallic or other suitable rigid parts comprising upper portions l and 4 in which the sprues and gate are-formed, intermediate portions 2 and 5 in which the valve tappets are formed, and lower portions 3 and 6 which carry a loose detachable metallic piece I, which is the portion against which the hardened face of the tappet solidifies. This piece I (Fig. '7) is slotted so as to engage with studs 8, these studs are screwed into the lower portion 3 and project through holes in the corresponding lower piece 6. These studs act as guides for pieces I when molds are open. It will be noted that piece I can readily be removed and replaced without interrupting producing operations. The intermediate portion 2 is provided with two perforated ears 9' and Ill, these cars engaged with corresponding pins 9 and In which project from the piece 5. The purpose of these pins is to insure that the molding cavities I3 located in 2 and 5 are in exact alignment. In the upper pieces I and 2 the trough II is provided. This trough suppliesmolten iron to the sprue l2-|2 leading to the cavities l3l3 in which the valve tappets are formed. The lower portions [4-44 of the valve tappet cavities I3-l3 are closedby the loose piece I.

A thermo couple I5 is located in this piece 1 and connected through leads Hi to an instrument l1, so that the temperature of the piece I can be maintained within a few degrees of 350 F., say between 300 and 400 F.

Operation-The molds are mounted in any convenient molding machine so that the caviti s of the molds will be in' alignment with each other.

Referring particularly to Fig. 2, a molten cast iron of a type suitable for chilling as, for example,

having a composition of :2 A. silicon, 3 carbon, .06% manganese, less than .1% sulphur and 25% phosphorus is poured into gates EE. By pouring this iron into the mold the temperature of the mold is raised. The molten iron exposed to the metallic mold parts cools fasten than does -'that exposed to the refractory material andconsequently forms a hardened region in the tappet casting.

I have discovered that when the temperature I at F is between 300 and 400 F. preferably 350, the surface of the iron which-solidifies at K has a Brinell reading between 300 and 400 R, which is a satisfactory figure to insure long life and little wear.

In Figures 4, 5, 6 and '7, it will be noticed that the cavities on the extreme'right will be filled up before those on the extreme left as the entrances l2 to the cavities l3 are lower on the extreme right than they are on the extreme left. The

castings are repeatedly made until the temperature on the portions I and 4 of the mold exceeds 400 F. or 500' F. and until the temperature of the part 1 raised above 300, therleliegter the temcontinues uninterrupted. As in Figures 2 the' mold is protected with Meloche coating as shown in United States Patents, 1,453,593; 1,492,694; 1,506,130; 1,560,838; and 1,568,234 in the trough H, the gates I2, part I3 and the upper portion of H. The surface of 1 against which the face of the tappet solidifies is, however, unprotected so that the full chilling effect is produced on the face ll of the tappets. ,In addition to the refractory coating a coating of lamp black is applied, as reierred to in Patent No. 1,492,694. The lamp black coating should be renewed between each casting and is also applied to the upper surface of the piece 1,. When the castings are removed from the mold the tappets are broken ofi from the gates |2-I2 at the shoulder formed at the junction between I! andl3. Provided that the mean'temperature of the mold is kept at 400 or 500 it will'be possible, I have found, to drill and tap the stem of the valve tappet so that the tappet adjustment screw can be screwed therein.

What I, claim is:

A molding machine adapted to produce cast iron valve tappets, comprising a three piece metal mold consisting of a matching pair having substantially vertical parting faces, and a third piece which is horizontal, against which the heads of the valve tappets are adapted to be cast; a plurality of corresponding mold cavities in the faces of the matching pair of molds, gates each arranged at a different level with respect=to said third piece and communicating with a connecting channel whereby the gates are successively fed with molten iron, said cavities being protected with a thin, adherent refractory, heat insulating coating, said horizontal piece being unprotected.

. JOSEPH LOUIS DOSTAL.

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