US2513939A

US2513939A - Construction of composite metal articles

Info

Publication number: US2513939A
Application number: US531743A
Authority: US
Inventors: Joseph H Hoern
Original assignee: Eaton Manufacturing Co
Current assignee: Eaton Corp
Priority date: 1944-04-19
Filing date: 1944-04-19
Publication date: 1950-07-04
Anticipated expiration: 1967-07-04

Description

July 4, 1950 J. H. HOERN 2,513,939

CONSTRUCTION OF COMPOSITE METAL ARTICLES Filed April 19, 1944 2 Sheets-Sheet 1 July 4, 1950 J. H. HOERN 2,513,939

0F COMPOSITE METAL ARTICLES Patented July 4, 1950 CONSTRUCTION OF COLIPOSITE METAL ARTICLES Joseph H. Hoern, Birmingham, Mich, assignor to Eaton Manufacturing Company, Cleveland, Ohio, a corporation of Ohio Application April 19, 1944, Serial No. 531,743

2 Claims.

This invention relates to a method of producing composite metal articles such as valves for internal combustion engines and more particularly to a method of making valves of metals having different chemical properties.

In the operation of present day internal combustion engines, due to the high temperatures and combustive gases generated by the leaded fuels used, the head and annular seat of poppet valves are subjected to corrosion and/or erosion. It has been found that a valve head and seat made of an alloy comprising 80% nickel and 20% chromium has effectively reduced the pitting or scoring of the head and seating surface. thereby prolonging the effective life of the valves. A valve head and stem made of 80-20 nickel-chromium, while practical, is objectionable primarily because of the relatively high cost of these metals.

It is the practice to form the stem andthat portion of the valve head not directly contacted by the combustive gases of a comparatively inexpensive metal having extremely high tensile strength characteristics at elevated temperatures such as an alloy comprising .40 to .50% carbon; .30 to .80% silicon; a maximum of .'l0% manganese; 13.00 to 15.00% each of chromium and nickel; .20 to .50% molybdenum; 1.75 to 3.00% tungsten; a maximum of .03% each of phosphorus and sulphur; and the balance of iron. The portion of the valve head and annular seat which is acted upon by corrosive or erosive elements is coated with a protective layer of nickelchromium or some like material possessing similar qualities thereto.

The nickel-chromium coating is usually manually applied to the valve head and seat by means of an electric or gas weld. In this method, regardless of the skill and experience of the operator, the valves in many instances when completed are found to have undesirable surface porosity and a protective coating of varying thickness. Such valves must necessarily be rejected causing decreased production and an increased unit cost.

It is the object of this invention to produce a valve of bimetallic materials in a less expensive and speedier method than heretofore; to provide a valve having a head and valve seat coated or overlayed with a coat of heat, corrosion, and/or erosion resistant material of uniform thickness; to provide a valve having uniform cohesion of the bimetallic materials throughout their juncture; to provide a valve of bimetallic materials having a uniform bond at their juncture which is free of blow holes; to provide a method of welding materials having different chemical characteristics by means of a powdered metal placed therebetween and the application of heat and pressure thereto; to provide a method of bonding dissimilar metals by preforming the metals to be joined, inserting and sealing within a preformed cavity a powdered metal having a lower melting point than the metals to be joined therebetween, and applying heat and pressure to the assembly; and to provide av method of making a composite metal article comprising preforming a pair of dissimilar metallic members, said members having complementary parts for assembly together, placing a powdered metal having a lower melting point than the metallic member, between the metals upon assembly thereof, hermetically sealing the powdered metal between the members, applying heat to the assembly sufiicient to displace the molten metal from between the members and provide for the bonding of the members together.

Other and further important objects and advantages of this invention will be apparent from the following description taken in connection with the drawings forming a part of the specification and in which:

Figure 1 is a perspective view of a cylindrical body member and a cap adapted to be welded together;

Figure 2 is a longitudinal sectional view of the ram and die of a forging hammer and through the assembled parts to be welded and forged prior to the forging stroke;

Figure 3 is a longitudinal sectional view, similar to Figure 2, showing the assembly after the initial forging operation;

Figure 4 is a longitudinal sectional view of the tassembly illustrating the second forging operaion;

Figure 5 is a fragmentary longitudinal sectional view of the completed article;

Figure 6 is a perspective view of a modified form of the invention showing the separate parts before assembly;

Figure 7 is a longitudinal sectional view of the assembled parts of the modification of the invention similar to Figure 2 of the preferred embodiment of the invention;

Figure 8 is a longitudinal sectional view, similar to Figure 7, showing the assembled parts after the initial forging operation;

Figure 9 is a longitudinal sectional view similar to Figure 3 after the completion of the second forging operation; and

Figure 10 is a fragmentary longitudinal secscience tional view of the completed article forming the modification oi the invention.

Ithas been discovered that by taking a pair of dissimilar metals, hermetically sealing therebetween a metal having a lower melting point than either of the other metals, melting the intermediate metal and applying pressure to the metals that an excellent weld can be obtained between the dissimilar metals to be united. When the metal possessing the lower melting point becomes molten the opposed surfaces of the metals to be joined are wetted so as to activate the surface particles thereof and provide for an efiective bonding of the surfaces upon application of pressure to the metals.

Referring to the drawings for more specific details of the invention, I represents generally a cylindrical member of metal possessing high tensile strength characteristics at elevated temperatures, comprising a body portion I2, a tapered portion I4, and an enlarged head I6. The head i6 is provided with a conical portion I8, the purpose of which will hereinafter appear.

A cap or crown 20 of heat corrosion and/or erosion resistant metal is adapted to fit snugly over the enlarged head I6 of member l0.

In the assembly and uniting of the member I0 and cap 20, the cap is partially filled with a powdered metal 22 possessing a lower melting point than either of the metals to be united and is placed upon the head I6 of the member I0 with the powdered metal completely filling the space between the surfaces thereof. The metal 22, although preferably in the form of a powder. ne-d not necessarily be limited thereto but may also be in the form of chips or a solid. Such a powdered metal may be one known commercially as Wilrich having a composition of .50 to 1.00% carbon; .25 to .'75% silicon; 8.00 to 10.00% chromium; 30.00 to 35.00% nickel; .50 to 1.00% manganese; 1.25 to 1.75% boron; with the balance iron. An annular weld 24 .is placed completely around the lower edge of the cap and upon the annular surface of head I so as to hermetically seal the powdered metal between members I0 and 20.

The assembly is then heated to a sufficient temperature to melt the powdered metal but not sufficient to melt the metals to be united. Inas: much as the powdered metal will have less displacement upOn heating, the assembly upon being transferred from the furnace is inverted and agitated so as to provide a wetting of the conical portion I8 of the cylindrical member and the inner surface 26 of the cap 20.

A die 28 having a cylindrical cavity 30, countersunk as indicated at 32 and adapted to receive the body portion l2 and tapered portion I4 of the cylindrical member I0, is positioned beneath a die 34 having a fiat horizontal face 30 carri d by the ram of a forging press (not shown). The assembly I0--22--20 is appropriately spaced beneath the die as illustrated in Figure 1; and a blow of sufficient magnitude is struck the cap 20 to substantially flatten, as indicated at 38, the conical surface I8; and concomitantly therewith the excess molten metal 22 is forced radially outward from the apex of the cone I0 beyond the margin of the points to be united to thereby effect a welding of the members I0 and 20 throughout their juncture. The blow administered to the assembly through the medium of the cap 20 causes the annular portion of the ca to bulge annularly outward so as to provide space for retention of the excess molten metal.

Although it has been found preferable to preform one of the members to be joined with a conical section as it so as to provide a more effective m. outward dlspersement of the molten metal, it would be sumciently satisfactory if the surfaces to be Joined were complementary to one another inasmuch as the molten metal would in either case tend to flow radially from the axis of the assembly.

The die 28, with the bonded assembly therein, is next shifted and positioned beneath a second die 00 having a concave cavity 82, also carried by a ram (not shown), and the assembly is forged herebetween to provide a convex head 84 as shown by Fi e 4.

After the completion of the second forging operation, the assembly is further forged and machined in accordance with the teachings of the patent to McBride, No. 1,984,751 to thus provide a finished composite article or valve as indicated at 46 in Figure 5.

In the modified form of the invention illustrated by Figures 6 through 10 herein, wherein the general procedure outlined relative to the preferred embodiment of the invention shown in Figures 1 through 5 is followed a cylindrical member I00 of a metal possessing high tensile strength characteristics at elevated temperatures includes a body portion I02, a tapered portion I04, and an enlarged head I 06. The head I06 has therein a cavity I08, the base of which is in the form of a cone H0.

A disk I I2 of heat corrosion and/or erosion resistant metal corresponding in size to the diameter of the cavity I08 adapted to be received snugly thereby is provided with an annular flange I I4 beveled inwardly as at H6. The cylindrical member I00 and disk II2 are assembled similarly to cylindrical member I0 and cap 20; the only difference being in the reversal of parts as regards the retention of the powdered metals therebetween.

A die II8 corresponding to die 34 has a frustrated conical portion I20 complementary to the cavity in the disk H2 and is employed similarly to die 34 so as to provide for initial forging of the assembly and the bonding. together thereof (In; the respective cylindrical member I00 and disk The remaining forging and machining operations are similar to those used in connection with the preferred embodiment of the invention with the exception that the resultant composite article or valve I22, as shown by Figure 10, is provided with a heavier seat portion than that obtained in the preferred embodiment of the invention shown by Figure 5.

While this invention has been described in connection with certain specific embodiments, the principle involved is susceptible of numerous other applications that will readily occur to persons skilled in the art. The invention is, therefore,

limited only as indicated by the scope of the appended claims.

What I claim is:

1. The method of making a composite metal article comprising preforming a metallic member having a conicalshaped head thereon; preforming a metallic cup-shaped member adapted to fit over the first member with contacting relation between the apex of the conical head and the inner fiat wall of the cup-shaped member; inserting a metal having a lower melting temperature than the melting temperature of said members between the members, assembling the members with the annular flange portion of the cup member in encompassing relation to the external periphery of the first member and hermetically sealing the metal between the members; applying heat to the assembly suflicient to melt the metal and simultaneously inverting and agitating the assembly to wet the surfaces to be bonded together and applying pressure to the assembly effective through the relative axial movement between the members to force the metal inserted between the members radially outwardly to an annular zone externally peripherally disposed to the first member between the flange of the cup-shaped member and the first member thereby bonding the members together.

2. The method of making a composite metal article comprising the steps of preforming a cylindrical member having a conical head thereon;

preforming a cap member of different materialthan said first mentioned member having a flat inner crown adapted to be associated with the conical head of the first member and an axially extended annular flange; placing a metal in said cap, said metal having a lower melting point than the two first named members; assembling the members with the flange of the cap member in encompassing relation with th external periphcry of thefirst mentioned member; hermetically sealing said metal between the members; heating said assembly sufiiciently to melt the metal placed in said cap; inverting and'agitating the assembly with the molten metal therebetween to thereby wet the surfaces to be bonded together;

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 427,924 Smith May 13, 1890 1,826,542 Hewig Oct. 6, 1931 1,826,549 'Jardine Oct. 6, 1931 1,886,615 Johnson Nov. 8, 1932 1,940,850 Derby Dec. 26, 1933 1,959,925 Pryde May 22, 1934 2,037,733 Mudge Apr. 21, 1936 2,059,584 Johnson Nov. 3, 1936 2,093,771 Colwell Sept. 21, 1937 2,119,042 Charlton May 31, 1938 2,133,292 Gordon Oct. 18, 1938 2,145,248 Chase Jan. 31, 1939 2,147,407 Huston et a1. Feb. 14, 1939 2,210,338 Quarmstrom Aug, 6, 1940 2,359,477 Hoem Oct. 3, 1944 2,403,926 Johnson July 16, 1946

Claims

1. THE METHOD OF MAKING A COMPOSITE METAL ARTICLE COMPRISING PREFORMING A METALLIC MEMBER HAVING A CONICAL SHAPED HEAD THERON; PREFORMING A METALLIC CUP-SHAPED MEMBER ADAPTED TO FIT OVER THE FIRST MEMBER WITH CONTRACTING RELATION BETWEEN THE APEX OF THE CONICAL HEADN AND THE INNER FLAT WALL OF THE CUP-SHAPED MEMBER; INSERTING A METAL HAVING A LOWER MELTING TEMPERATURE THAN THE MELTING TEMPERATURE OF SAID MEMBERS BETWEEN THE MEMBERS, ASSEMBLING THE MEMBERS WITH THE ANNULAR FLANGE PORTION OF THE CUP MEMBER IN ENCOMPASSING RELATION TO THE EXTERNAL PERIPHERY OF THE FIRST MEMBER AND HERMETICALLY SEALING THE METAL BETWEEN THE MEMBERS; APPLYING HEAT TO THE ASSEMBLY SUFFICIENT OF MELT THE METAL AND SIMULTANEOUSLY INVERTING AND AGITING THE ASSEMBLY TO WET THE SURFACES TO BE BONDED TOGETHER AND APPLYING PRESSURE TO THE ASSEMBLY EFFECTIVE THROUGH THE RELATIVE AXIAL MOVEMENT BETWEEN THE MEMBERS TO FORCE THE METAL INSERTED BETWEEN THE MEMBERS RADIALLY OUTWARDLY TO AN ANNULAR ZONE EXTERNALLY PERIPHERALLY DISPOSED TO THE FIRST MEMBER BETWEEN THE FLANGE OF THE CUP-SHAPED MEMBER AND THE FIRST MEMBER THEREBY BONDING THE MEMBERS TOGETHER.