US2113895A - Steel tappet construction - Google Patents

Description

" April il2 1938.V H V -F.MARAI\)IDEV 1 STEEL TAPPET CONSTRUCTION 7 Original Filed July 29 1935 fraki' Mqrazzie.

' AgoRN Ya Patented PF- 12, .1938 V steel valveftappets for internal combustion en- I fenginecamtothe valveistem andrequireahard,

3 wearr'esisting i'ac'efor' contact with the cam but I at thesameftime the iace must not be so brittle 11 s to be easily fractured u iiderimpact;

Cast iron camengaging heads or wear portions have, previously been 'employedin tappet .beiugmore fragile an'd brittle thansteel. In-

engine speeds andincreased valve loads have made itnecessary and desirable to provide subject to fracture'under impact.

. Various steel constructions otgtappei's have been proposed, but Iallot these require a :25 considerable'amount of forging and a deformav tlon and'rewor i oi the hard steel of thetacing or head member. Steel head members or tacings 5 and showing, respectively, the ,tappets prior to and after the "forging operation for simultanepusly effecting extrusion otthe head portion and upsetting or the body portion. have been comhaving the desired wegrmg qualities are so hard that they are not easily machined or worked by.-

Q30; forging. According to thep'resent invention, a construction is provided in. which forging or j machining of theiace or head member is sub- .j stantially eliminated so'that the disadvantages of reworking a hard steel material and ot'causing development of flaws and inequalities of distribution during 'such' forging operationfiare eliminated. n V s 1 f T'lhe principal obiect ofjthis invention vis to 1 improve the art ottappet construction. a

facing'or head member and of the body member desired hardness of both members anait enmi J-wnate stresses between 'such'parts. I i

It "is also an oblect of the-invention to provide 1 l an (extremely; light weight g tappet construction I which includes considerably less metal than "conyentionally. employed, but at the-same time provides the desired strength andresistance to wear 1 a m end imnack ,Aiurther object: is .to provide atappetlconstruotlon having arelatively thin facing or, head Z'Ihis invention relates to the construction of t, I I

M afford a cushioning, efiectkand allow the tappet fgine'sQand as division of myco-pending applig c non, Serial,No; 33,723,"flled.July29; 1935, m y, 51 QSteeI-tappet constructions,- and assigned to the,

. same; assignee y as is thei present applicationv Tappets are used totransmitythethrust of the constructions, and while. they provide a. good iwearlng' surface, they, have the disadvantage of; e

in a tappet construction a head member which 1 fizoi has fwearing qualities practically comparable to.

cast iron, but which is stronger, lighter and less t head portions of the tappet assembled in a weld- Another object is to provide a tappet con-, 3 *struction in which the metal orIalloy of boththe y e and i 1 Fig.11 is a side elevation of .a'completed tappet' oi' -the tappetfare sensitive to "the same heat treatin'g and quenchingprocess to obtain the were; emaawaw wne w one:

s'rsnn'rarrm cons'rauo'non: u u

Saginaw, Mich, assl'zfioriq Eaton- Manufacturing Company, "Cleveland, I oliimacorporationolohis 4 v I k .ongims pnc aon duly 29, iosslsenai Not as,- 723'. Divided andthls application December 12, 1936, Serlal No.,115.5Q2 w I t me (or 123- 90) gins, thereofso. that it will fle x sufficiently to to follow the surface of the operating cam them-g tappet relative tothecam shaft.

Other objects ieatures --and advantages will become apparent from theiollowingw description for and substantially ellminateubounce .oi! the .and theapmnded-elaims. m

For the pur se ofillustratingthe genus of the Figure I is a sideelevation, partly in section, of the body portion of ;;atappet madein accordance with the principles of this invention;

Fig. 2 is a top or bottom plan of the head p01- jti'onot a tappet shown in Fig. 1; '2 i Fig. 3 is an end vlew, ln'elevation,oi." the head portion'shown in Fig. 2;

Fig. 4' is a view similar to Fig.4 or the body and mg 111: for-fthe initial welding, operations.

a Fig. 5 is a view similar to Fig. 4 showing the tappet after the welding operation has been completed; H V.

Figs. 6 and 7 are views similar to Figs. 4 and plated:

Fig. 8 is an elevation, partly in section and similar to Fig. 3, lot amodified form otatappet body mountedin a welding fixture and with a head. portion assembledthereonprior to theweldm pperation.

Figs". 9 and ware views similar to Figs. 4 and I 5 01' a further modified form of tappet body prior toand afterthe head-portion has been welded of the type illustrated in'Figs. 9 audio.

Referring to the drawing, andmore especially toFigs. .1 to 8, inclusive, the body portion ofthe tappet consistsof atubularmember I, prefer-,- ably composed of steelor an alloy thereoi-, pre-- as indicatedat l, The lower endofthe-tubular member is provided with a reduced bore which is threaded as indicated at 5, inFig. 1, to-receive "underside oi! the flange is also slightly. beveled an adjusting screw or stud which may be threaded in or out of the lower end of the tappet for adjustment purposes, The lower end of the tubular member I is reduced in outside diameter as C, when heated and at a temperature of about 1500-1520 F. and quenched in 'oil. This steel affords good resistance to wear and, is readily machined and forged.

A wear piece or head member attached to the body-member I is'shown in Figs.

2 and 3 and consists ofa preformed annular disc of wear and impact resisting metal or alloy. Standard specifications. A; E. 52100 steel con stitutes the preferred material of the disc or head" member 8; 'This material is composed 'of approximately 0.95-1.10%- carbon; 0.20-0.50% manganese, 1.20-l.50 chromium, OAS-0.30% silicon, 0.03% maximum phosphorus, 0.035% maximum sulphur, and the'balanc'e iron. Other steels or steel alloys may be be used in construction of head portion 8 such as 3% tungsten tool steel, a tool steel known by the trade name Ketos, and

standardspeciflcation S. A. E. 6150 steel. One

form of 3% tungsten tool steel has approximately 1.20-1.40% carbon and 3.00-5.00% tungsten, the balance being principally iron, while a quite similarform of tungsten tool steel has approximately,

1.35-l.50% carbon, from0.50-1.00% chromium, from 0.20-0.30% vanadium, and from 3.50-5.00% tungsten, the balance be principally iron. Ketos steel has approximately 0.90-1.00% carbon, about1.50%manganese, 0.50-0.60% chromium and 0.15-0.20% vanadium, the balance being principally iron. Standard specification S. A. E. 6150 steel contains approximately. 0.45-

0.55% carbon, 0.50-0.80% manganese, 0.80-1.l%'

chromium, 0.18% vanadium, 0.04% maximum phosphorus, 0.045% maximum sulphur, and the balance iron. While this steel does not produce quite as great hardness as the standard specification S. A. E. 52100, it is noted that the wearing qualities of the head member may be improved by cutting said head members from bar stock in which rollingoperations during, the production of the bar stock have caused the grains of the steel to be arranged axially of the piece. When such head members are employed in a tappet the wearoccurs across the ends of the grains of the steel rather than in the direction of the flbers characteristics when heat treated. It is preferred to employ the latter steel for the head member [since it aiiords the necessary hardness and wear resisting qualities. The 3% tungsten tool steel also affords the necessary hardness and in this characteristic is slightly superior to the "Ketos steel. Standard specification S.'A. E. 52100 steel is, however, more economical to produce' than the tungsten toolsteel or Ketos" adapted to be steel, and is particularly desirable for the present tappet since its heat treating characteristics are essentially the same as that of the steel employed in the body portion of the tappet. It will be noted that in each instance, a steel alloy containing a metal of the chromium family, i. e.,

the chromium-molybdenumvtungsten-uranium family, is used and in certain instances, other hard metals such as manganese and vanadium are also employed to harden the steel alloy. It

a will also be noted that in each instance, a steel alloy contains about 0.55-1.50% carbon. When the carbon content is at or near the lower of such limits, it is necessary to employ, about to 8% of the hard metal in the alloy. With a carbon content from about 0.90-1.50%, the hard metal content may be reduced to from about 1 to 5%,

thuseflecting I an economy in the cost of the material used for the cam engaging portion.

I The disc I may be formed vby any desired method such as punching from sheet or bar stock, stamping, casting, or otherwise fabricating the same tosubstantially the desired ultimate size of the tappet head when the disc is made of one of the above described materials or a similar material which afl'ords the desired wearing'and impact resisting qualities. Where the wear resisting quality of the material selected for the tappet head'is not otherwise quite. sumcient, the disc may be forged from bar stock so that wear of the head member or wear piece will take place across or transverse to the end grain of the steel rather than in the direction of the fibers of the material in order to obtain the desired wear resistance. 'A disc 8 of substantially the desired ultimate size of the tappet head'is indicated in full line in Figs. 2 and 3. This disc, however, may be made 1 smaller than the ultimate head size but of greater thickness, as indicated by the dot and dash outlinein Fig.3, so that the discs may be spread and thinned out'in the forging operation during formation of the tappet.

Referring to Figs. 4 to 7, inclusive, the method of Joining the body and head members i and I,

preformed as above described, consists in mounting the body I in a hollow welding electrode 8 and then positioning the heador disc 8 .on the flange 2 of the body member with the underside of the disc] in contact with the thin line contact portion 3 formed at the upper. edge of the flange 2.

The second welding electrode ii is then brought against the upper'surface of the head member or disc 8 and the welding circuit closed. The

welding current passes through the thin line I the nature of a progressive welding operation and of the material. Standard specification S. A. E.

52100 steel-has somewhat more chromium and about twice the carbon content of the S. A. E.

is carried out in the manner describedso as emciently to utilize the weldingcurrent and to secure as broad a homogeneous weld between the parts as is possible with the possible area of contact between such parts. The provision of the thinline contact between the head and body members causes the metal of the flange 2 to melt with considerable rapidity first at the'point of contact which aflords the path of least resistance, and causes pro-heating of adjacent parts of the flange! and the head member 0, so that when the two parts come into full contact, as

shown in Fig. 5, a substantlally'uniform weld will a or this die cavity beieghlatdto control to I oi approximately 2.75 -3.5% carbon,]0.4 j1.l0%

manganese, l.70'- -2,60% silicon, 0.204).3037 phosphorus, 0.115% "sulphur, and the [balance iron.

completed acrossfthe tallest 'width fl nt t .1, another method of welding head and margins of the flange 12 This, ,however, machining operations necessitate additional J i I whichare not desirable becauseof cost. After the head member! has ben weldedtof the body member I OIili'; as above described, the

i a desirable "forging temperature and placed in a die'me'mber II, as shown inFig. 6. ,Tl'iisdle memi ber'i's provided with a longitudinal cavity oi'a assembled article, if desired, may be reheatedto sizeadapted 'correctly to receive that portion of also,

i toward the reducedcavity which receives the lower part 01' the body I" or I, the inclination being i at a degree slightly less than thebevel 4, on the under side jot the flange 2 01-12; The inclination some extent thedirection oi displacementor -upsetting of the metal of theffiange 2 or I'm the iorging operation; lifter the assembled construetion has been placed in thefdie memberffl, it is c-:.-g; .lengaged by apunch l3, and flange member 2" or 2" and-the headmem'ber are forged together as y: shown inFig. 7. The: forging -operi a.tioncauses In the flange 2 or? to be deformed in both direcfiside .01" the"head member 8 and the body member 'l and 'reworks the initial weld between the head I Asanwbody members;**"'ll1isnot only strengthens" the weld but also'broadens the bearing between the head member a and'flange 2. The forging a t :as toextend the support ofthe flange 2 or! outwardly towards the edges 01! the head member a and also radially'inwardly of the walls of the body member I or If so thatthe thickenedwalls of 55. U s the tappet bodyaflord a greatly increasedarea I 01' support at the point where the greatest strain occurs duringuseofthe tappet. The extent to which extrusion of the metal of the head meml or 1- and extrusion ofthe metal 01' the flange {or 2'noutwardly-toward the outer margin of- 3 the head member8 maybe controlled by regulatstem orbody portion I of the tappet and finish. grinding the end face of the head portion 8 re- 1 main to be done; The above indicated'heat $113,896 of the portions ma involve the' use r a modified term; of tubular body I shown in Fig. 8,' 'such body member being providedwitha flange 2" 'so formed, "thatjthe line contact portion 3 lies. at thev diametrically outer frnargin oi' the flange .211 Although an acceptable .weld may be obtained with the form of flange shown Fig. 8,the most" desirable practice is to form the flange s'o that' 1 the line contact portion is at the diametrically; j inner mar gin of such flange; It is also possible to obtain an, acceptablq'weldf by so forming the l5"flange,2 thatthe iinej oi conta'ct between it and i the head member will initially "occur at a point" "intermediate the diametrically inner and outer" with'an enlarged cavity of a size corresponding,

tions withrei'erence tothemajor axis 'of the'tubu ilar body, broadens'the contact between the under 1 operation mayalso be carried to such an extent ber l into the tubularend or the body member" ing thetravel'of the punch ll. Th'epurpose of suchextrusion of metal is to secure embracing engagement bet ween the head member" treatment involving a 1500-1520 1 quench m J jblvlaives the bodyportion I of thetappet a hard-'- jhess'ot about 40-50, or abovenockwell scale C, .-1, 1or',the major portion of such body membenand gives the head portion ahardnessoi about 55, or more, on the same scale. Vi The i'or'ging operationm'aybe accomplished cold or with such heat .jas remains in'the unit after the welding-.-operation,although itis preferable tore-'heat -the ,assemb yvbemre rorging.

a method. of making a preferablyfr'nade by casting v and is composed of a suitab le steelpr-alloy which is capable of hardjenin'gjby heat treatment. The body portion 2 I isca'stso .as'toprovide afhbllowtubular portion with a relativelylarge bore '22 through the major portion'fthereoi" and toprovide relatively thin walis'soias tofeliminate as much weight as possible.

for adiustingthe' clearance between'the end 'ofthe valve stem of Jan internalcombu'stion engineand the tappet. .A- lock nut .26 may be provided :tor maintaining such adjustment. Openings or windows 24 maybe providedin' the walls of the body portion 2| Iorlfurther lightening the weight or" a tappet; for distributing, lubricant between 'the walls otthe tappet and the guidetherefor and admitting air for cooling purposes to the interior of the tappetggThe portion 2|" is preferably cast in a permanent mold. and may be of a steel or alloy such asja material composed This material is sensitive to the heat treathead portion 8: of the "previously described embodiment, and composed ofessen'tially thesame material the head portion '8, to produce substantially the same hardness of head portion and body portion aspreviously indicated. The upper -'=surface ofthe body portion 2| is beveled to provide a .thin annularline contact portion 21 to facilitate progressive welding of the head and body portion of the tapp'et and to produce uniform "welds'int'he manner above described. The-body member 2| is mounted in aholiow electrode 9' and the headmember '8' is then positioned on the upperend 01' the tappet'body withtheunderside or the head member in contact with the line a contact portion 21. i A second welding electrode I0 is then brought against the upper surface of the head member 8 and the welding circuit closed. The" progressive fwelding operationis carried out o r in the manner above 'described'sufflciently to utilize; the welding current and secure as broad 'and homogeneous 1 a weld between the parts 8' and]! as, is possible with the available area of contact betweensuch parts.

' 'Ihetappet may then be subjected to a heat treatment for hardening the same by reheating the tappet so as to obtain the proper hardness and thenqu'e'nching in oll'wh'enat a temperature oi from 1500 to 1520 F. The tappet may then be finish ground and the adjusting screw 25 and lock nut 26 assembled thereon. The thickness or the cam engaging" disc 8 is preferably approximately equal to, or but slightly greater than the thickness or the peripheral walls of the body portion II. .The disc 8' is supported only adjacent I Referenceimay now be had tol 'igs. 9, l0 and o H1 1 inwhich is depicted barrel type .tappetr. Body I] of said :tappet ls the periphery thereof by the body port on 1i so that the disc will flex sufllciently to afford a cushioning effect during operation of the tappet, V

and the tappet will follow closely the surface of an operating cam and eliminate bounce relative to the'crank shaft.

As many changes may be made in the above described constructions, and many apparently widely different embodiments of this invention could be had without departing from the spirit thereof, itis intended that all matter contained in the above description or'shown in the accompanying drawing shall be interpreted as illus-' trative and not in a limiting sense. no

What' is claimed: is: Q 1. As an article of manufacture, a .lreat-treated tappet including a' body portion integrally bonded to a cam engaging portion, said body portion being composed of a steel consisting of substantially 1.35-1.65% manganese, 0.30-0.40% carbon and the balance principally iron,and said cam engaging portion being composed of a steel consisting of 0.20-0.50% manganese, 0.95-1.10% carbon, 1.20-l.50% chromium and the balance'principally iron, so that when both of ,said portions are a heated and at a temperature'of. about 1500 to 1520 F. are quenched in oil, stresses between the. joint portions are substantially eliminated and the body portion has a hardness of from 40 to 50,

Rockwell scale C, and a cam engaging portion has a hardnessof about 55, Rockwell scale C.

2. A tappet construction comprising a tubular body portion of medium carbon steel integrally bonded to a substantially disc shaped wear por-, tion of a steel alloy containing ametal of the chromium family, the grain of the steel of said wear portion being disposed substantially par allel with the axis of said tubular body portion.

3. A tappet comprising a hollow tubular steel body and a steel cam engaging portion in the form of a disc having a thickness not materially greater than the thickness of the walls of said body portion, said disc being secured to and supported by said body' portion only adjacent its periphery so as to flex sumciently during operationof the tappet to afford a cushioning effect whereby the tappet follows closely the surface of the operating cam therefor.

4. As an article of manufacture. a heat-treated tappet including a body portion integrally bonded to a cam engaging portion, said body portion be ing composed of a medium carbon steel and said cam engaging portion'being composed of a steel alloy selected from a group of steels consisting of standard specification S. A. E. No. 52100 steel, "Ketos" tool steel, and 3% tungsten tool steel,

5 both of said portions being sensitive we heat 1.35-1.65% manganese,,0.30-0.40% carbon, and the balance principally iron, and said cam engaging portion being composed of a steel alloy selected from the group of steels consisting of standard specification S. 'A. E. No. 52100 steel, Ketos tool steel and 3% tungsten tool steel,

both of said portions being sensitive to a heat treatment involving heating said portions to a temperature above 1500 F. and at a temperature of from about 1500 to 1520 F. quenching in oil to produce a hardness of about55 Rockwell scale C for the cam engaging portion and a hardness of 40 to50 Rockwell scale C for the major portion ofv said body portion.

8. As an article of manufacture, a heat treated tappet including a body portion integrally bonded to a cam engaging portion, said body portion being composed of amedium carbon steel and said cam engaging portion being composedof a steel alloy including from 0.55-1.50% carbon, from 1 to 8% hard metal selected from a group of hard metals consisting of chromium, tungsten, molybdenum, uranium, manganese and vanadium, and the balance being principally iron, both of said portions being sensitive to a heat treatment involving heating said portions to a temperature above 1500 F. and at such temperature quenching in oil to produce a hardness of about 55, Rockwell scale C, for the cam engaging portion and a hardness of 40 to 50, Rockwell scale C, for the major part of said body portion.

'1. As an article of manufacture, a heat treated ;tappet including a body portion integrally bonded? to a cam engaging portion, said body portion be ing composed of a steel consisting of substantially 1.35- 1.65% manganese, USO-0.40% carbon, and the balance principally iron, and said cam engaging portion being composed of a steel alloy including from 0.55-1.50% carbon, from i to 8% hard metal selected from a group ofhard metals consisting of chromium, tungsten, molybdenum, uranium, manganese and vanadium, and the balance being principally iron, bothof said portions being sensitive to a heat treatment involving heatingsaid portions to a .temperature above 1500 F. and at such temperature quenching in oil to produce a hardness of about55, Rockwell scale C, for the cam engaging portion and a hardness of 40 to 50,,Rockwell scale C, for the major part of said body portion. 5

8. As an article of manufacture, a heat treated tappet including a body portion integrally bonded to a cam engaging portion, said body portion beingcomposed of a medium carbon steel and said cam engaging portion being composed of a steel alloy including from 0'.55-1.50% carbon, from 1 to'8% hard metal selected from a group of hard metals consisting of chromium, tungsten, molybdenum, uranium, manganese and vanadium, and the balance being principally iron, both of said portions being sensitive to a heat treatment involving heating said portions to a temperature of about 1500 F. and at such temperature quenching in oil to produce a hardness of above 50,

, Rockwell scale C, for the cam engaging portion and a hardness of above 40, Rockwell scale C, for the major part of said body p rtion.

FRANK MARANDE.

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