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Publication numberUS2436931 A
Publication typeGrant
Publication dateMar 2, 1948
Filing dateAug 25, 1944
Priority dateAug 25, 1944
Publication numberUS 2436931 A, US 2436931A, US-A-2436931, US2436931 A, US2436931A
InventorsWilliam J Marencik
Original AssigneeThompson Prod Inc
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Method of preventing scaling during the forging of hollow metal articles
US 2436931 A
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Description  (OCR text may contain errors)

March 1943- w. MARENCIK METHOD OF PREVENTING SCALING DURING THE FORGING OF HULLOW METAL ARTICLES Filed Aug. 25,. 1944 a .i w

1 M W B Patented 2, 1948 METHOD OF PREVENTING SCALING DUR- ING THE FORGING OF HOLLOW METAL ARTICLES William J. Marencik, Pal-ma, Ohio, assignor to Thompson Products, Inc., Cleveland, Ohio, a

corporation of Ohio Application August 25, 1944, Serial No. 551,195

This invention relates to a method of P ing scaling during the forging of hollow metal articles, and more particularly to-a method of preventing the scaling of the internal surface of a cup-shaped metal blank in forging the same into a hollow head valve.

In making hollow head poppet valves for aircraft or other automotive engines, a cup-shaped metal blank is subjected to a series of hot forging operations to form an elongated solid stem portion and a head portion provided with a cavity therein. One such method is described and claimed. in the McBride et al, Patent No. 1,984,751. During the hot forging operations, which are carried out at a sufficiently elevated temperature to cause scale formation, scale forms on the internal surface of the cup-shaped blank and remains on such surface after the forgingoperations are complete. It has heretofore been a very difficult and expensive task to remove this scale in finishing the hollow head valve for the reception of a coolant, such as metallic sodium. This scale must, however, be completely removed to prevent contamination of the coolant with the scale and also to obtain an eflicient rate of heat transfer through the metal of the valve to the coolant contained within the hollow head thereof.

I have now found that the surface of a hollow metal article can be satisfactorily protected from scaling and oxidation during the hot forging thereof from blank forms if the internal surface of the blank itself is sealed against the entrance thereinto of air and hot gases during the forging steps. In accordance with my present invention, this is accomplished by applying a metal cap to the open end of the blank and deforming the metal of the blank to secure the cap in place thereon. The cap is so applied and secured in place while the blank is cool and the internal surface thereof entirely free from scale or oxides. Since the cap then remains in place during the subsequent hot forging operations, or other form of heat treatment, the internal surface of the blank has no opportunity to become oxidized, other than through the action of the small amount of air sealed within the blank at the start. to be objectionable, but if it should prove to be so, the air in the blank cavity can first be displaced by means of carbondioxide. or other inert gas. Carbondioxide is preferred because being heavier than air, it will displace air if introduced into the blank either in gaseous form, or in the form of solid carbon-dioxide.

As a further protection for the internal sur- This amount of oxidation is not sufilcient 5 Claims. (01. 29-15) faces of the blank during the hot forging operations, the capped end of the blank may be coated with glass-forming ingredients, such as frit, as disclosed in the copending application of myself and Robert E. Ahlf, Serial No. 551,194, filed August 25, 1944. Ordinarily, however, if the metal cap is properly secured in place on the open end of the cup-shaped blank, as by peening over the metal of the blank, a gas-tight seal is thereby provided that prevents the occurrence of scale formation on the internal surface of the blank during the hot forging operations; The metal cap remains in place during the forging or other operations and becomes included in the metal of the blank. Prior to the forming of the finished hollow metal article, the portion of the forged blank that includes the metal of the cap is removed. The internal surface of the article has now been prevented from becomin scaled during all of the operations performed in making the finished article that involve scaling temperatures.

It is therefore an important object of this invention to provide a method of preventing-the formation of scale and oxides on the internal surfaces of metal articles during the hot forging of the blanks in the production of such articles.

It is a further important object of this invention to provide a method of preventing scale formation during the hot forging of metal blanks in the manufacture of hollow metal articles, such as hollow head valves and the like, wherein the interior of the blank is sealed by a metal cap while the internal surface thereof is free from scale or oxides, the cap remaining in place during the subsequent hot forging operations to seal the interior of the blank and protect the internal surface thereof until after all operations at elevated temperatures have been completed,

Other and further important objects of this invention will be apparent from the disclosures in the, specification and the accompanyingdrawing.

0n the drawings:

Figure 1 is a longitudinal sectional view of a cup-shaped blank with a metal can applied to the open end thereof and with a peening hammer in position before striking the end of the blank to peen the metal of the blank about the periphery of the metal cap.

Figure 2 is a view similar to Figure l with the peening hammer in the act of performing the peening operation.

Figure 3 is a longitudinal sectional view of a icup-shaped blank with the cap secured in posiion.

Figure 4 is a longitudinal sectional view of the valve blank in one stage of its manufacture after being subjected to a hot forging step.

Figure 5 is a longitudinal sectional view of the valve blank after being subjected to a further hot forging step that results in closing-the stem end of the valve blank.

Figure 6 is a longitudinal sectional view, similar to Figure 3, illustrating the application of a further protective coating over the capped end of the blank.

Although the invention here illustrated and described is applied to the manufacture of hollow head valves, such as aircraft valves, it will be understood that it is similarly applicable to the manufacture of any hollow metal article which is formed from a cup-shaped blank by a series of hot forging operations. In the case of a hollow head valve, these hot forging operations include the use of hammers to reduce the diameter of the blank adjacent its head end and thereby form a neck portion, and also the use of extrusion dies, swedging dies, upsetting dies, and the like. During such hot forging operations, temperatures are used, such as in the neighborhood of about 1,800 to 2,100" F., that would normally cause scale formation on the surfaces of the metal blank. Since these operations are of themselves well known and some of them are described in the McBride et al patent above referred to, they will not be explained in detail here.

The reference numeral it indicates generally a cup-shaped blank such as is used in the forming of a hollow head valve. The blank I is itself the result of a series of prior operations and comprises an enlarged head portion II and a stem portion l2 of slightly reduced diameter. Within the head portion II is a head cavity l3 which merges into a stem cavity ll. Prior to the start of the operations about to be described. the valve blank ID has been machined to leave the internal surface of the head and stem cavities l3 and I4, respectively, clean and free from any scale or oxides.

With the valve blank It in the cleaned condition indicated, the open end of the blank is sealed before the blank is subjected to any high temperatures in the course of manufacturing the hollow head valve.

As illustrated in Figures 1 and 2, the open stem end of the blank Ill is recessed, as at [5, to receive a metal cap I6 to provide a seal for the interior of the blank. Said metal blank i6, which may be formed of stainless steel or other suitable metal, is preferably initially dished to give it a convexity upwardly as illustrated in Figure 1. The metal cap it is placed in the annular recess l and then struck with a peening hammer II. The bottom face of said hammer I1 is provided with a segmental spherical concave surface I8 centrally and with a surrounding conical recess it. The action of the hammer I1 is thus to give a segmental spherical contour to the metal cap l6 and to cause the metal of the end of the blank to fiow over and around the periphery of the metal cap l6, as at 20. The cap "5 is thereby firmly sealed in place and the internal walls of the blank III are sealed against the entrance of air or gases thereinto.

Starting with the capped blank III as illustrated in Figure 3, the blank is subjected to a series of hot forging operations as a result of which the blank passes through the stages illustrated in Figures 4 and 5. In one of the hot forging operations, the blank I0 is reduced to provide a neck 2| and an elongated stem portion 22, also of reduced diameter. The metal cap ll during this forging step becomes deformed and assumes a slightly angular shape. The shape is of no particular importance except that it indicates the behavior of the metal cap when the blank is subjected to the forging operations to form the neck and stem of reduced diameter. when a stainless steel cap is used, no diillculty is experienced from the cap breaking or rupturing.

In a second forging operation, the valve blank I0 is subjected to an extrusion step that results in closing the stem of the valve to provide an elongated closed stem 23 and a head cavity 24.

The metal of the cap l6, now indicated by the reference numeral Ilia, is enclosed within the metal of the elongated stem 22. Since the mass of the cap metal 16a is substantially at the extremity of the stem portion, the stem end can be severed, as at the dotted line 26 (Figure 5) to eliminate the cap metal entirely from the finished valve. Subsequent operations beyond those illustrated are carried out to produce the finished valve, but since these operations do not involve temperatures at which scaling would take place, no further protection of the surface of the head cavity 24 is required. The elongated stem 23 is drilled out to permit the introduction of a coolant, such as metallic sodium, into the head cavity 24, and the valve blank otherwise finished in accordance with well known practice.

In the modification of my invention illustrated in Figure 6, in addition to a metal cap it. the end' of the valve blank l0, including said cap I6, is provided with a coating of material, such as frit, capable upon fusing of forming a glassy protective layer 26. To accomplish this, an aqueous suspension of frit is applied to the end of the valve blank ID, as by dipping or spraying, to form a layer 26 thereover. After the end of the blank has been coated with a layer of the aqueous frit suspension, it is subjected to a preliminary heating step, as by heating to about 200 F. to dry the frit coating to form a dry, relatively hard adherent layer 26. During the subsequent hot forging operations, this layer 26 becomes fused to form a glassy protective coating over the entire end of the blank, thus insuring complete protection of the interior wall of the valve blank during the hot forging operations. As before stated, the cap continues to protect the interior as the valve takes shape, because it does not resist deformation but collapses upon itself without breaking the seal. The glassy coating 26, however, protects against the possibility of the metal cap i6 drawing away from the peened over metal bead 20 to produce a leak in the seal.

In accordance with the principles of this invention, therefore, hollow metal articles may be protected against surface oxidation or scaling by the use of either a thin metal cap alone or a metal cap and a protective glassy coating to seal the blank cavity during hot forging operations.

I claim as my invention:

1. In the method of making a hollow head valve in which a cup-shaped blank is subjected to a series of hot forging operations, the improvement whereby scaling of the internal surface of the blank is prevented, which comprises applying an outwardly dished metal cap to the open end of said blank to seal the empty cavity therein, peening the metal of said blank about said cap to secure the same in place and seal the interior of said blank, and subsequently subjecting said blank to hot forging operations.

5 a 2. In the method of making a hollowhead valve in which a cup-shaped blank is subjected to a series of hot forsinz operations, the improvement whereby scaling of the internal surface of the blank is prevented which comprises applying an outwardly dished metal cap to the open end of said blank to seal the empty cavity therein, peening the metal of said blank about said cap to secure the same in place and seal the interior of said blank prior to subjecting said blank to hot forging operations, hot forging said blank to form a hollow head, a reduced neck and an elongated solid stem with the metal of said cap included in the end of said stem and removing said stem end that includes the metal of said cap.

3. In the method of making a hollow head valve in which a cup-shaped blank is subjected to a series of hot forging operations, the improvement whereby scaling of the internal surface of the blank-is prevented, which comprises applying an outwardly dished metal cap to the open end of said blank, peening the metal of said blank about said cap to secure the same in place and seal the empty interior of said blank prior to subjecting said blank to hot forging operation, hot forging said blank to form a hollow head, a reduced neck and an elongated solid stem with the metal of said cap included in the end of said stem and removing said stem end.

4. In the method of making a hollow head valve from a cup-shaped blank by a series of hot forging operations, the improvement preventing scaling of the internal surface of said blank,

which comprises applying an outwardly dished metal cap to the open end of said blank while securing said cap in place by deformation of the metal of said blank to seal the empty interior thereof, subjecting said blank to hot forging operations during which the metal of said cap becomes included within the metal of said blank, and thereafter removing the portion of the blank that includes said cap metal.

5. In the method of making a hollow head valve from a cup-shaped blank by a series of hot forging operations, the improvement'preventing scaling of the internal surface of said blank, which comprises applying an outwardly dished metal cap to theopen end of said blank to seal the empty cavity therein while the internal surface is clean and free from scale, securing said cap in place by deformation of the metal of said blank, applying a frit coating over said cap to protect the cap end of said blank and to seal the interior thereof, subjecting said sealed blank to hot forging operations during which the metal of said cap becomes included within the metal of said blank, and thereafter removing the portion of the blank that includes said cap metal.

WILLIAM J. MARENCIK.

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

UNITED STATES PATENTS Number Name Date 1,364,565 Lloyd Jan. 4, 1921 1,409,562 Mason Mar. 14, 1922 2,005,306 Wallis June 18, 193E 2,081,645 Squires May 25, 193'. 2,093,771 Colwell Sept. 21, 193'.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US1364565 *Dec 27, 1917Jan 4, 1921Dunford And Elliott SheffieldManufacture of hollow metal rods, bars, and the like
US1409562 *May 6, 1920Mar 14, 1922Mason William HProcess and apparatus for enlarging hollow metal articles
US2005306 *Jun 21, 1934Jun 18, 1935Nat Tube CoMethod of making tubes
US2081645 *Jul 5, 1933May 25, 1937United Aircraft CorpMethod of producing propeller blades
US2093771 *Feb 27, 1931Sep 21, 1937Thompson Prod IncMethod of making copper cooled valves
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US6851165 *Sep 24, 2002Feb 8, 2005Siemens Vdo Automotive, Inc.Apparatus for retaining a poppet seal
Classifications
U.S. Classification29/888.451, 29/423
International ClassificationB21K1/22
Cooperative ClassificationF01L3/14, B21K1/22
European ClassificationF01L3/14, B21K1/22