US1479121A - Two-piece valve and method of making same - Google Patents

Description

W. H. WASHEU- Two-Pimm VALVE AND METHOD 0F MAKING SAM Filed Ooi. 24,

jan, s E924 Patented Jan. l, 1924.

UNITED STATES PATENT YoFFIcE.

WILLIAM H. WASHBURNIE, OF CHICAGO, ILLINOIS, ASSIGNOR TO THE OLIVER TYPE- WRITER COMYANY, F CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

TWO-PIECE VALVE AND METHOD OF MAKING Applicationled October 24, 1921.

Jul Improvement in Two-Piece Valves and- Methods of Making Same, and declare the following to be a tull, clear, and exact description of the same, such as will enable others skilled in the art to which it pertains to make and use `the same, reference being had to the accompanying drawings, whichl form a part of this specification.

It is desirable in puppet valves for internal combustion engines to have the head made -out of a heat-resisting alloy -while the stem is made -out of a wear-resisting. or

friction-resisting alloy. Heretofore the com' mon' practice o making valves of this kind has been to screw the heads on thel ends of the stems and, after riveting over-.the ends of the stems somewhat, welding the heads and'stems together. This is not only an expensive process butlit 'introduces welding stresses which frequentl cause warping in the stems just under the heads or close to the point -where the welds are made. Consequentlyvalves Imade inthemannerjust de'- scribed are not only expensive but they are frequently/defective. c Y The object of the Apresent invention isto produce a perfectl two-part poppet valve in a simple and'no'vel way and at a low manufacturing cost.. 'f ,i Y

The various.;f eatures :of novelty whereby myA invention is characterized -will 'hereinafterbe pointed out with ,particularity in the claims; but, for a full understanding of my invention and of its 'object and advan- 40 tages, reference may be had to 'the' following detailed description taken in connection with the accompanying drawing, wherein:

Figure 1 is a vertical section through a pair .of forming dies' ready to-closeupon a 4.5l rudimentary valve head and-.fashion it and secureglt, tol a stem held in position to receive it' .fa

tu the condition,-existing when the dies have been closed nithef-workaand A Fig-3 is, iside. elevatfon ofthe completed valve-head andgtheadjacentportion of the Serial No. 509,948.

In accordance with my invention I first make' a finished stem, something which can be accomplished at a very low cost by automatic machinery into which is fed rod or heavy wire stock. A rudimentary head iS then placed on the end ot' a stein and is simultaneously forged into a completed head and attached to the stem in such a manner that no stresses tending to produce warping or distortion are produced, and permitting the completed valve to be placed directly in service after the single finishing operation of grinding the valve face.

Referring to the drawing, l represents the lower die and 2 the upper die of a forging machine. The lower die has a central hole or chamber 3 into which a valve stem 4 accurately fits. The hole or chamber is closed at the bottom so that the valve stem will rest on a solid support at its lower end. In the top of the lowerdie, co-axial with the hole 3, is a mold cavity 5 having the shape of a completed valve-head. The bottom of the upper die may be simply a flat surface although there is preferably a central recess orI depression 6 slightly larger in diameter than the diameter of the valve stem, so as to insure thatthere will always be a clearance between thelupper end of the valve Stem and the upper die or betweenthe upper die and any metal which might flow across the top of the valve stem from the rudimentary valve during the forging operation.

- That portion of the valve stem'which lies within the mold cavity 5 when the stem is dropped into the lower die is provided with superficial irregularities adapted to interlock with the metal of lthe valve-head. These irregularities preferably take the form of an ordinary screw thread 7 extending throughout the length if that portion of the stem that lies above the bottom of the mold cavity.

l/Vhile the valve stem is placed in the di in a finished condition, the head, when placed in the die, is a mere rudimentary blank in the form of a thick washer` as indicated at 8. The hole 9 in the blank -is made somewhatlarger in dia-meter than the the stem and, instead of being cylindrical, is preferably madey in the form of a frustum of a cone the smaller 'end of which lies at diameter of the screw threaded portion of per die forces the metal of the blank in the' fthe screw threads.

the bottom when the blank is placed in the machine. The thinnest portions of valves of the kind under consideration are the marginal portions and there is usually a grad ual increase in thicknessv toward the center solthat the thickness or depth is greatest at the center. 3 I therefore prefer to make the valve-head blank thickest at the middle and decreasing gradually in thickness towardtlie periphery.

In buildinga valve, a stein'is dropped down into the lower die, the stem being at ordinary room temperature. The for the head is heated to a high temperature, preferably one approaching welding heat. The hot blank .is then dropped into the mold cavity' in the lower die and the upper die is driven down. 'he shape of the blank is such that in the first instance it is supported only at the margin, so that as soon as the upper die engages with the top ofthe blank it' starts to press the center of the blank down. Since the opening in the blank is larger in .diameter than the stein, the downward movement of the center of the blank takes place just as though the stem were not present. Only after the bottom of the blank has been shaped to the mold cavity excepting only at the middle where the boss or hub in the completed valve is to appear, the continued downward movement of the up# vicinity of the stem downwardly and also inwardly toward the axisot' the stein. As the metal flows down into the bottom portion 10 of the mold cavity which is for the purpose of giving shape to the hub or boss on the under side of the valve-head, it finds itself confined by a rigid surrounding wall and it `tlierefore can flow only inwardly toward the axis of the valve` namely upon The definite vnim'f'nnent of the metal in the head toward 'the axis begins at the bottom and progresses toward the top so that it may be said that the head is forged or molded so as to bringzit'pro-V gressively into interlocking engagement with the screw threads oii the stein from the bottom of the head toward the-top. lThis is considered of importance because thev advantages secured from lie working of the metal of the head in forging itA into shape are not lost through the creation of shearing stresses which begin to shear away the metal of the head lying next to the valve stem ,while the downward flow or movement of t-le main portion of tliemetal is taking p ace. upon the lower die there will or' course be a downward pressure on the metal ofthe head immediately ad'aeent to and surrounding the stem, but t is will serve only to insure perfect contact at all times between the screw threads and' the metal of the head,v and there may also be a slight dis- When the upper die is fully closedtortion of the lowermost screw threads which will produce a. locking effect' if it be attempted to 'unscrew the head.

ject'ed to anforces which will alect it in any way, t e vprincipal stresses' that are applied to thestem being the radial stresses as the material of the head is forged inwardl toward the airis. 1t will also be seen t iat by for ing the head while heated toa degree whic permits'itto fiow readily under pressure, there-will be no unbalanced internal stresses which might produce warping or distortion after removal of the valve 'from the dies. Consequently when the valve is removed from the mold it is ready to beput into use asfsoon as it becomes cool, the only finishing operation that is neces- It will be seen that the stern is not sub-A .l i

sarv being the grinding of the valve face 11.

Whenthe two parts of the valve are assembled in the pressthe difference in temperature between them is greater'. than it will ever be thereafter, the stem being pracf tically cold, namely at roomtemperature, and the valve being at 'approximately a welding heat. At the end ofthe for ing isted when both the stein and the headwere cold. Iii other Words, when the head cools f, thereby. maintaining the relative condition which exf after/the Valve has been. taken out of l'the` dies',it shrinks and `increases its grip on the comparatively cool stein, which grip would be decreased if the head' coul ain be heated without correspondingly heating the stem, but which 'will remain. practically constant if the stem be heated at the same time that the head is heated as is the case when the valve is put into service.

I claim:

1. The method of making a two-part valve which consists' in inserting the '-screw threaded end of a stem into a cone-sha ed hole in a valveliead blank larger in diameter at the smaller end than the stem, and then forging the blank so as to cause the metal to flow toward the center and progressivelyA fill the screw threads in the stem beginnin with the threads inthe small end of the ho e and lsiinultaneousl-y give to the blank the contour of a valve-head.

2. The methodof making a two-part valve which consists in resting one end of a cold 4finished stem on a support, lcating a heated to the blank the shape of a valve head, and

then completing the valve by grinding the valve face.

The method of making a two-part valve which consists in inserting a stem into a cone-shaped hole in a heated valve-head blank, and then forging the blank so as to.

cause the nietal to flow towards the center and pro ressively engagethe stem from the portion ying adjacent to the smaller end of the hole to that portion lying adjacent to the larger end of the hole and simultaneously give to the blank the contour of a valve head.

4. The method of making a two-part valve which consists in inserting the end of a stem having grooves extending around the same, into a cone-shaped hole in a hot valve-head blank larger in diameter at the smaller vend than the stem, and then forging .the blank so as to cause the metal to flow toward the center and progressively fill the4 grooves in the stem'beginnin with the groove in the small end of the ole and simultaneously give to the blank the contour of a valve head.

5. The method of making a two-part valve which consists in insertin a stem into a hole of lar er diameter exten ing through a hot valve-lgiead blank, so as to leave the end of the stem exposed and free, and then forging.

the blank. so as to cause the metal to flow towards the center into intimate contact with lthe stem and simultaneously give to the .blank the sha e4 of a valve head, without v,exerting any orging end of the stem in the of the stem.

pressure on the said direction of the length 6. The method of making atwo-part valve which consists in inserting a comparatively' cold stem into a hole of larger diameter extending' through a liilily heated valve-head blank, and then forging the blank to cause the metal to flow toward the -center into intimate contact with the stem and simultaneously ive to the blank the shape of a valve head without exerting any forging ressure on the stem in the eiigth ofthe stein. '7. The method of making a tw'oart valve which consists in inserting. a shoul ered portion of a stein into a hole of larger diameter extending through a heatedvalve-head blank, and then forging the blank without exerting any forging pressure on the exdirection of the posed end of the stem,so as to cause theI metal to flow toward 'the center into intimate contact with the stein and simultaneously give to the blank the contour of a valve head.

8. The method of making a twoart valve which consists in, inserting a shoul ered portion of a cold stein iito a hole of larger diameter extending through a highly heated valve-head blank so as io' leave an end of the stein adjacent to the blank free and exposed, and then forging the Blank by exerting a. pressure on the saine only on the surfaces thereof sui'rounding sa .d hole 'and without exerting any forging pressure on-said exposed end of the stem so as to cause the metal to flow toward ihe center into'intimate contact with the stem and simultaneously give to the blank the contour of al 4the stem is left free, to cause the metal of the blank to flow toward the center into intimate contact with the stem and: simultaneously give to the blank the shape of a valve head.

10. The vmethod of making .a twoart valve which consists in heating a was erlike blank of approximately the diameter of the valve to be formed, inserting in the hole iir the blank a part near one endof a. stem smaller in diameter than said hole, and then forging the blank in dies one of which has a recess somewhat larger in diameter than the stem and adapted to register with' said end of the stemwhen the dies are closed and'thus placing endwise forging pressure on avoid the stem..

11. The method of making a two-part valve which consists inresting one erd of a 'cold stem on a support, locating a heated washer-like blank of approximately the diameter of the valve head to be formed so that it surrounds the stem in the vicinty of the other. end and leaves the latterend free and exposed, and then forging the blank without imposing any forging pressure on the last mentioned end of the stem so as to cause the metal of the blank to flow into intimate contact with the stein and simultaneously give tq'the blank the shape of a valve ead.

In testimony whereof, I sign .this specification.

WILLIAM H. WAsHBUInna`

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