US2748466A - Method of making engine hub and shaft unit - Google Patents

Description

v. BROWN 2,748,466

MAKING ENGINE HUB AND SHAFT UNIT June 5, 1956 METHOD OF Filed Feb. 8, 1952 United States Patent METHOD OF MAKING ENGINE HUB AND SHAFT UNIT Victor Brown, Elmhurst, Ill., assignor to Kropp Forge Company, Chicago, 11]., a corporation of Illinois Application February 8, 1952, Serial No. 270,703

1 Claim. (Cl. 29-553) This invention relates to an improved method of forming articles of forgeable material comprising a shaft having an integral enlarged portion at one end thereof, and more particularly to an improved method 'of forging asteel engine shaft having an integral hub or wheel at one end.

In the forging of articles such as steel axles, the general procedure involves the use of a stock piece having a thickness or diameter that is not only greater than the shaft but also greater than the journal or other special section which is integral with the shaft. The stock piece is first heated to a forging temperature and then placed between open dies in a forge for reducing or drawing down the stock piece. The forging ordinarily is begun at the middle of the stock piece, which may be rapidly reduced by heavy blows of the forge hammer; and the forging progresses toward a free end of the stock piece as the drawing down to shaft size is accomplished. By

the use of different sized dies, the journal portion at the.

area of the piece, the greater the amount of work that must be expended during the drawing down operation. Also, the tediousness of the operation and the wear and tear on the dies are functions of the work that must be done. Moreover, excessive amounts of work done on a given stock piece may result in appreciable alteration of the characteristics of the metal.

In a typical engine shaft having an integral hub, or wheel the hub diameter is substantially greater than the shaft diameter and, in'the production thereof by a procedure' such as that just mentioned, a very great amount of work is required in reducing a stock piece from approximately the hub size to the shaft size. On the other hand, upset forging of a shaft size stock piece to form the hub at one end thereof would ordinarily involve such a substantial increase in the cross-sectional area of the piece at the hub portion that undesirable characteristics would be developed in the metal thereat, and an excessive amount of extra work would probably be recertain sequence of process steps, so as to reduce to a minimum the defective and undesirable possible results that might be obtained by the use of either of such operations alone.

It is, therefore, an important object of the instant in- 2,748,4b6 Patented June 5, 1956 vention to provide an improved process of forming a shaft having an integral enlarged portion at one end thereof.

It is a further object of the instant invention to provide an improved process of forging an engine shaft having an integral hub at one end thereof, particularly if the hub is substantially greater in diameter than the shaft.

It is another object of the instant invention to provide an improved process of forging an engine shaft having an integral hub at one end, which comprises first upset drop-forging the hub at one end of a suitable stock piece and subsequently drawing down to shaft size the remainder of the forging.

It is still a further object of the instant invention to provide an improved process of forging an engine shaft having an integral hub at one end, which comprises upset drop-forging the hub at one end of a suitable stock piece, necking down to shaft size the upset forgingimmediately adjacent the hub, and drawing down to shaft size the remainder of the forging.

It is still another object of the instant invention to provide an improved process of forging an engine shaft having an integral hub and shaft nub at one end of the shaft, which comprises upset drop-forging a suitably cylindrical stock piece to accomplish simultaneously a two-three to one reduction in diameter of the piece to form the shaft nub, and a two-three to one expansion of the piece adjacent the nub to form the hub, trimming the forging, then necking down the forging to shaft size immediately adjacent the hub and simultaneously completing the hub formation, and next drawing down the forging to shaft size inwardly of the necking.

It is also an important feature of the instant invention to provide an improved forging process wherein the operational advantages of upset drop forging are obtained by carrying out such a step initially, using a piece suitably designed to reduce to a minimum the strains incurred during such operation, and subsequently employing "a drawing down process, during which reheating of the piece may be employed to reduce any strains which might have been created during'the upset drop forging operation.

Other objects, features and advantages of the present invention will become apparent to one skilled in the art from the following description of the embodiment illustrated in the accompanying drawings, in which:

Figure 1 is a side elevational view of an upset drop forging obtained by carrying out the initial upsetting operation of the invention, using a stock piece having approximately the dimensions shown in broken lines;

Figure 2 is an end elevational view of the upset drop forging of Fig. 1, taken from the hub end of the forging;

Figure 3 is a side elevational view of the aforementioned drop forging after the completion of a necking down operation according to the instant invention, also showing a fragmentary sectional view of the necking dies in position;

Figure 4 is a fragmentary sectional elevational view taken substantially along the line IV-IV of Fig. 3; and

Figure 5 is a side elevational view of an engine shaft having an integral hub at one end obtained by carrying out the process steps outlined in the foregoing figures.

As shown on the drawings:

In Figure 1, the broken lines designated by the reference numeral 10 indicate generally a generally cylindrical stock piece of suitably forgeable material, such as steel,

which may be used in carrying out the initial upset drop The metal stock Prior to i the work piece is heated to suitable forging temperatures in the manner well known in theart.

The work piece 10 is then: positioned between a pair of upset drop forging dies, which define in cooperating position a space of theprecise shape and contour of the upset forging designated generally by the reference numeral 11 in Figure 1.

The manner in which upset drop forgingoperations are carried: out is generally well known in the. art and need be described. only briefly herein. In such an. operation the stock piece 10 would, of course, be positioned vertically with, for example, the left end uppermost, instead of'in the horizontal position shown in Figure 1. In adrop forging operation the cooperating dies (not shown)", define theexact shape. of the article to be forged. In. this case the upper or hammer die (not shown) has a. recessrcorrespondingto. the shape ofthe portion of theforgii g 11, at the. left of. the line. XX of Figure. 1';.and1 the lower or anvil. die. (not shown)". has a. recess. eorresponding to the shape of the portion of the forgingll at the rightl of the. line.X:.-XI. Upset. forging or upsetting involves a reduction in the. length. of the stock piece by exertion, thereagainst of opposed longitudinal. forces, such, as. by the repeated. dropping or hammering of the instant: upper die against the leftrhand. end of the work piece. 10 of Fig.- ufel while. the.rig h trhand end. of, the. work piece is sup.- portedby the instant lower die,.functioning as an anvil. I

Any, particular portion of the workpiece which is to be changed. in shape during the upsetting operation is heated to; forging temperature prior to commencement ofthe. operation. In.the-instant.examplehere shown, the. entire workpiece 10 ispreferably heated toforging tern perature. against the. piece10 on the lower die,. the workpiece It). assumes the form; of the forging 11' and, the upper and. lower diesgcome. face to. face, causing the slight amount of excess metal to-ex-trude as flash, outwardly in theplane defined-or designated by the line X-X in Fig ure 1 The operation, of. trimming; the. flash, which, isnextcarried out inthe process of the invention, is carried out inthe manner, well knownin the art andthereforeneed not; be. ere es bed particularly important. advantage of the; useof an. ini droptforging operation-inthe instant invention, em:

ploying closed instead of open dies, resides in the fact that.

aeanrate; die. design. may be used to. control. the precise total an ounttofmetalto be employedintheprocess and;

thereby, for example, to: determine. the. precise overall dimensiOnS: Qf; the.-finally forged product that is. obtained.

after, carrying outrthe; subsequent; steps of. the invention.

Iteferringgagain to; Figure 1, it-will be seenlthat at. the-i extreme rightend; of the. work piece. 10 a. shaft nub. 12

is formed, having 3.111 average; diameter c. of perhaps 4 inches. Theformatiom of. the: nub 12,-.thus-.invo1v.e s a reduction in;the.:diameten or thickness; which. is preferably: a reduction-of.about 2a3' to. Lin.the-practice of theinvention. The: nub is formed of: course, by driving; the; end:

portion .ofthe work-piece 10 into asuitably;designerkslight: ly; tapering: recess in the; bottom. die

The shaft nub 12 is centrally mounted on an;outw ar.d- 1y-.. taperedbossrlike face 13 of. theengine hub 14;v The bossrlike face; 13.. of the; engine hub; 14; may, thus. be.

erationbyexpansion of thezdiameter or thickness of the workpiece to an approximate diameter d of perhaps'2'0 inches; The expansion thus.obtainediispreferably. about. 2-3. to 1' in the;practice.of: the: invention.

In. the: practice of. the instant: inventionit. has; been After. repeated hammering of the upper die.

found preferable, in the upset drop forging operation, to effect an expansion also in the remaining portion'16' of the forging 11. As shown herein, the remaining portion 16 is positioned centrally on the inside face 15 of the hub 14 and has a slightly tapered generally cylindrical shape, with a rounded end 17 terminating the remaining portion 16 of the forging 11. The-resulting average diameter e of the remaining portion. 16 isperhaps 12 inches, and preferably the ratio of' the hub diameter dto the diameter e is 5 to about 2-4 in the practice of the instant invention.

It has also been found that it is generally preferable in the. practice of the inventionto employ a ratio of the diameter e to the diameter a of about 5 to 3-4, and most preferably about 3 to 2. The reduction. in the Work piece length b to the overall drop forging length 1 in the instant example may be a reduction of 30 inches to about 24 inches, and is preferably a reduction of about 10 to about 9-7.

Inthe instant example, it has been found that an alteration of. the dimensions of the work piece 10 during the conversion thereof to the. upset drop forging 11 within the aforementioned approximate dimensional ranges is particularly suitable for the formation. of the drop forging 11 so as to obtain an optimum combination of. a

minimum amount of work expenditure and a minimum.

amount of internal strain creation during the forging, Also,.a minimum amount of overall material loss maybe obtained thereby incarrying out the complete process of theinvention, as will be pointed outhereinafter.

The next, step involved inthe instant process is the trimming of the flash from the drop forging 11. along the line X' X.of*Figure 1. As hereinbefore mentioned,.such a procedure is well known in the art and the details thereof; need, not. be set forth herein.

The next forging operation in the process of this invention is called. a necking, or a necking down operation. suchrpigocess is carried out, as is indicated in Figures 3 and 4. of the. drawings, by the use of upper and lower open swage-likedies 18 and 19, respectively, having mounted therein concentrically aligned, generally hemi annularl'y shaper, inwardly. tapering fuller-like die members 20' and 21,..respectively.

As will.be. seen,.each of. the. dies 18. and 19 has a first hemi-cylindrical recess 22. adapted to provide clearance betweenthedies 13 and19 andthe extreme periphery. of the. hubl4. Definingthe inward peripheral portionof the surface. of. the. recess 22.in each of the dies 18 and 19 is.a,semi-annular ledge- 23, adapted to be positioned flush with the inwardface 15 of the hub14 for maintaining the proper. cooperative position between. thedies 18 and. 19 and the..hu b.14.

The die members 20 and 21 in the upper and. lower dies 18. and .19. respectively are positioned-slightly inwardly. of the. ledge. 23 in. each. die and cooperate with. the

ledge 2 to definea ShOllldfCf-likC'I'fiCGSSg of generally, out: wardly, tapered semirannular. shape in each of the dies 18.ancL 19. The die walls. of that. recess impart to theforging 11: (Fig.3); a central concentric circular boss'portion lflrmounted'onttheinward face 15 ofthe hub 14. It will thusbeseen that the completion of the bossrlike. portion;- 242 of thehub. 14 is. accomplished. simultaneously pletevtheformationiof the shaft 25, as designated in Figure; 5. In the instant example, the diameter g; is-perhaps-S inches; thereby; resulting; in a necking down reduction of By'means ofj'repeated hammering betweenspanner;

approximately 12 to 5 and preferably about to about 3-6, in the practice of the invention.

As is best seen in Figure 4, the dies 18 and 19 mounting the cooperating die members and 21, respectively, are open, as contrasted to closed (drop forging) dies. In other words, such dies are not shaped so as to conform precisely with the ultimate shape desired in the forging, particularly with respect to the annular groove or necking that is cut in the forging 11' adjacent the hub 14. The use of open dies in many instances, and particularly in the present instance, has been found to reduce appreciably the general Wear and tear on the necking dies, as well as the internal strain creation during the necking operation.

It should also be noted that the dies 18 and 19 cooperate to define a pair of semi-cylindrical mating walls 26 inwardly (from the hub end) of the die members 20 and 21. The walls 26, when the dies 18 and 19 are matingly aligned, conform substantially to the shape and contour of the contiguous face portions of the remainder 16' of the forging 11'. The walls 26 may thus cooperate with the ledges 23 to check the alignment of the forging 11' at the end of the necking operation, when the walls 26 are brought into contact with the remainder 16' of the forging 11'.

It will also be appreciated that since the dies 18 and 19 are open dies, it would not be necessary to employ a corresponding die member 20 and 21 in both of such dies. The necking operation could be accomplished effectively by the use of a pair of dies wherein only one die contained the die member such as the die member 20 or 21. By rotation of the forging during the necking operation, the formation of the complete annular groove as well as the complete boss-like portion 24 of the hub 14 could be accomplished.

The next step in the process of the invention is the step of drawing down or reducing to shaft size the remaining portion 16' of the forging 11 of Figure 3 to obtain the shaft portion 25 shown in Figure 5. Drawing down is a well known forging operation which need not be described in detail herein. In general, the portion 16 is forged between generally hemi-cylindrically grooved swages (not shown). Preferably, the hammering down to shaft size is started at the portion of the forging near the necking and is worked on down the rest of the forging away from the hub 14.

The drawing down operation, as well as the prior trimming and necking down operations must, of course, be carried out upon forgeable metal heated to forging temperatures. In the instant example, it is usually desirable to reheat the forging at least once, and preferably twice, during the drawing down operation. In this respect, the instant invention provides a unique advantage in that all such reheating is carried out after the initial upsetting operation, so that any internal strains created during upsetting may have maximum opportunity to be released during the working as well as the reheating operation of the instant process, all of which are carried out subsequent to the upsetting operation. As is known, the drawing down operations usually tend to reduce internal strain as well as to consolidate the fibers of the metal.

After the drawing down operation has been completed the resulting forging indicated generally by the reference numeral 26 in Figure 5 comprises an engine shaft having an integral hub at one end. The forged article 26 is cooled slowly to prevent flaking, and then checked for straightness. If straightening is required, preheating to about 1000 F. is usually necessary.

Next, the article is heated to about 1575" F. and maintained thereat in a continuous furnace for about five hours, and then oil-quenched. Immediately thereafter, the article 26 of the instant example is tempered in a continuous furnace at about 1100 F. for nine hours, to obtain 269 to 321.

Each of the forgings is, of course, serialized and given routine physical properties tests, including Brinell hardness. Also, various machining operations are usually carried out. For example, the shaft nub 12 would ordinarily be partially trimmed off and rounded down to remove the taper, and an annular recess would ordinarily be cut in the boss 24 on the hub 14. It will be appreciated that the instant forging process of the invention makes possible, by the use of an initial upsetting operation and a subsequent necking down operation, a minimum material loss and a minimum amount of machining in carrying out each of the aforementioned machining operations.

It will, of course, be understood that certain of the various foregoing details of structure and operation as herein set forth relate specifically to the instant example described herein, and various of such details may be varied through a wide range without departing from the principles of this invention; and it is not, therefore, the purpose to limit the patent granted hereon otherwise than necessitated by the scope of the appended claim.

I claim as my invention:

A process of forging a steel engine shaft having an integral hub and shaft nub at one end of the shaft, which comprises upset drop-forging a suitably cylindrical steel stock piece to accomplish simultaneously a. 23 to 1 reduction in diameter of the piece to form the shaft nub and a 2-3 to 1 expansion in diameter of the piece ad jacent the nub to form the hub, trimming the forging, then necking down the forging to shaft size to accomplish a 10 to 3-6 reduction immediately adjacent the hub, and forging by hammering down the forging to shaft size inwardly of the necking.

References Cited in the file of this patent UNITED STATES PATENTS 141,680 Van Patten Aug. 12, 1873 602,940 Hall Apr. 26, 1896 1,325,067 Wilcox Dec. 16, 1919 1,911,180 Corlett May 30, 1933 2,027,980 Horton Jan. 14, 1936 2,057,924 Smith Oct. 20, 1936

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