US2446515A - Method of forming bearing structures - Google Patents

Description

1943- R. 1. NJWEINGART 2,446,515 METHOD OF FORMING BEARING STRUCTURES Original Filed Feb. 12, 1943 Patented Aug. 3, 1948 UNITED STATES PATENT OFFICE METHOD OF FORMING BEARING STRUCTURES Richard I. N. Weingart, Glen Head, N. Y.

Claims. 1

This invention relates to an improved method of forming a novel bearing structure designed primarily, though not exclusively, for shafts in measuring instruments, horological instruments, and the like, and has for its principal object the provision of means for forming a novel bearing element wherein end play of the shaft can, at the time of manufacture of the instrument, be reduced to a predetermined and desired minimum. The present application constitutes a continuation of my copending application Serial No. 549,238, filed August 12, 1944, now abandoned, which constitutes a division of my co-pending application Serial No. 475,692, filed February 12, 1943, now Patent No. 2,376,406. I

End play of shafts in any instrument or apparatus can be reduced by increased accuracy in construction of the parts. This greatly increases the cost, however. In any given instance, if the tolerances are decreased ,by one-half, the cost may increase four or five times, and this results in prohibitive cost of the instrument. Measuring instruments generally are subjected to considerable vibration. These instruments normally have a plurality of shafts, includinga driving shaft and a driven shaft. This continuous vibration causes continuous endwise shifting of the shaft, which, in turn, causes the driving and driven gears'to cut into each other in a short time, and thus greatly reduces the accuracy of the measurement.

' An important object of the present invention resides in the provision of means and a method for reducing this endwise play, in the case of measuring instruments such as pressure gauges, speed indicators, and the like, from $003 or .004, to 1.0003 or .0004, without requiring a reduction of the tolerances of the individual parts, and without increasing the final cost of the instrument.

Another object of the present invention is the provision of an improved method of forming a novel thrust-bearing element which is simple and inexpensive to manufacture, and which provides a flat, polished thrust-bearing surface, thus greatly reducing friction in the shaft.

In the drawing:

Fig. 1 is a transverse section taken through an instrument frame showing a bearing formed in accordance with the method of the present invention before the shaft has been freed for rotation.

Fig. 2 is a section taken on line 22 of Fig. 1.

Fig. 3 is a broken sectional view showing a modified form of the bearing structure constructed in accordance with the method of the present in- Vention.

Fig. 4 is a broken sectional view illustrating one method of carrying out the method of the present invention for obtaining a predetermined amount of end play in the shaft.

Fig. 5 is a sectional view similar to Fig. 1, but showing the relation of the parts after the shaft has been freed for rotation, the amount of end play, however, being shown in exaggerated form.

Fig. 6 shows an alternative method of carrying out the present invention.

Fig, '7 shows another method of forming the bearing structure where the bearing frame rather than the bearing bushing is staked.

Figs. 8 and 10 illustrate an alternative form of the method of the present invention.

Figs. 9 and 11, respectively, are sections taken on lines 9-9 of Fig. 8, and lll l of Fig. 10. I

Referring now more particularly to the drawing, Fig. 1 illustrates a fragmentary View of a movement for a measuring instrument including spaced frame members It] and H, which may be maintained in such spaced relationship by'means of spacing bushings (not shown). It will be assumed that a shaft 24, which carries a bushing 28, to which is secured a driving member 29 such as a sector gear, is to be journalled between the frame members [0 and l I. These frame members are provided with aligned apertures 4t and 4| which receive bearing bushings 42 and 43, which are similarly formed and are provided with bearing apertures 44. In many instances, the bearing bushings should be of harder metal than the metal forming the frame members. The external diameter of bearing bushings 42 and 43 is such as to be received snugly with a force fit within apertures 40 and M in the frame members.

Before each bearing bushing is inserted within its aperture, its inner surface 45 is staked at a plurality of points adjacent to the periphery, as illustrated at 46 in Fig. 2. This staking or upsetting may be done with a die or punch formed with a plurality of spaced punching points or flat surfaces adapted to engage this inner surface t5 adjacent to its periphery. When the die is in engagement with this surface, it is struck a forceful blow which displaces some of the metal outwardly, as shown at 4'1. This step of moving the metal outwardly at a plurality of spaced points on the inner surface of the bearing bushing-adjacent to its periphery may also be accomplished by a slow application of pressure, although-the upsetting method possibly is preferable. Whichever method is used, however, the result will be generally that shown in Fig. 1. 7

An equally satisfactory result may be obtained by knurling the periphery of the bushing 50, as

shown in Fig. 3, adjacent to this inner surface 52. This knurled surface is shown at 49, and the forming of the closely-spaced indentations causes the metal between the indentations to move outwardly, thus forming a plurality of closely-spaced splines 51 in such outer periphery. Another way of accomplishing the result is to cut agitualspl-i nes by removing the metal, all as is well known in the art. For convenience in description, these projections, which lie outside the periphery of the bearing bushing in its initial state, will be referred to hereinafter as splines. The initial diameter of the bushing may be such to have a close fit in the frame aperture, but not necessarily a force fit.

When the bushing is inserted within the aper- I ture in the frame, it may, in one form (ii-carrying out the invention, be inserted'from'the inner end of such frame aperture. The bushing is moved outwardly, and in the. course of this outward n ment. the splines e entually ro oh he n--. in the t e heel-ll. to ou slots o keyways in the aperture. bushing may thus he mo ed out ardly throu h the i ems p rtu to a oin whe ein i s inne sllriaoo is ub-stow tielly p ane with. th least s fa e o he frame members. as shown in F l and 3- By ov din a snu lit between he oil-spline oor ion of the bushing and its suppo g aperture the bearin in a iens itsel he per ur before he are is. subsequ nt li t does not disturb this. a l-lamesthe shaft all is tornoo w; -tl e usua red terminal p tion-s. r .,,t iu iormine shoulders 5 which enga e thei luers lrtaso ii o th boat n bushin ss m si rls o ho spac bushings n th s inst n e, relative to the math oitl o sha net-w e v o oo cdshould ls it, is. a o caus the. urfaces o hearinabu llioes. 42. and 43-: toionease s ob shoulll rswil h e en a air loe as o essure the i e embers. ar init ally a se bled= The o ies. however! need no l o too ne in. Vie 9 the subsequen oDenfilliDI-l. lnot lor wor s ome oom hers ere nit l ir. asso rlblsdt le beesl slousl ine nga e-the laolll o of. th shalt ith sumcient-pr s oe-to firoozo heshait ae lnst-rota oa The Hoist stop n; he m thod is illustrated. i 4. One frame. :rnomber l. res ed est t tlonarr. die {illv havin an apert re ill. of, s ightly ereaterzdiameter than. that of bushin 48. In other words. when framemombel I l; isoosi l d.

of. he. upos te frame la. a so n t enga n -b shing 42., B165. .7 l on str lok a liellt low witlla and bushil-la l whioh is arr ed in m monit r ilacnotmo e-downwaro r due to. eng ment with shoul er .5 o haft all, i will be apparent tha su h. rame member-V I 9. moved downwa ith toleranc to tha us li. o it which i oar ith us sis i rood ou war ly n the anorure. 3f tlY @I h0 .$?l@d ih of. a a. time! test ae the sha t at oroa blo .t be eadily deter-m lled when e sha t is ir oto urn and. a uch ti .e t willoo obs rv d tha h one E oy ftris. almost-. mno oontibla Tho r lati n ts whonthe beatlnestruoture s. fin shed qiltb la ssllewn i'Eis-fil t o lslt ioursa s Shows further outward movement of the bearing bushing.

When both dies are recessed, as shown in Fig. 4, each blow causes both bearing bushings 62 and 43 to move slightly outwardly in their supporting frames, although if one die is a fiat surface, the blow wil a se onl e earing bus in to m v outwa d y, namely the one adjacent o the recessed die, and in such a case the frame may then be reversed and the opposite frame member struck, thus according similar treatment to the other; bearing bushing. It has been found in actual practice that good results are obtained by the arrangement shown in Fig. 4, although excel lent results have also been obtained by a slow application of pressure to the opposite frame members rather than the quick hammer blow.

One method of employing a slow application of pressure is illustrated in Fig. 6 wherein frame members [0 and H are illustrated as supporting shaft 24 in bearing bushings 42 and 43. The st um n u ilized may c prise a subs nt ally Q-s aped clampin member 6 having a recessed hea po ion 65 which engages frame-member Ill without engaging-bearing bushing 42, Atits lower end the clamping member is provided with ahorizontal portion 66, wh ch s pp r s, a. mi rome er screw havinaa thumb turn 8 or other means fo permittin manual tation f the sc e A its inner end the screw engages the center .of shaft 24, It will thus beseen that as the screw turned, the upper shoulder '55 of the shaitbears against earing bushing .42 and forces it outwardly in its su o i g ap rture in lira-me mem er 10 Screw 51 is provided with graduationsj and frame pore. tion 66 is likewise provided with a fixed reference ri ea es may be provided thousand f a m lt b or the shalt 24 lsiui iall rozen aga s rotatio In the event that the micrometer screw is turned to p mi ngitu al movem nt one-thousandth o an n h f r each artial rota on. an the shaft then test d o ation, it w l be-s enth t when thes aft finally rotates, the nd playwill not be. more han neh usandth oi an ch In other rd ifj-t shalt has oue housandth oi-an nch clearanc betwe n. its. opposed. sh ulders and the hearin bushin t may iroe y r tatav Accord inely-rif: he mic om ter lead s rew is n t. moved more man ehou n th of; an nch between sue. ssi-ve tostme o sha t. t r rotation. the boa b ing 42 will no have. been moved outwardhrm ro han one l ousaudt l or an. nch be ween its os t on. wherein it ire z srshaf 24 a ainst rotation, audits posi ion whero -ur fr es tl e shaf lo ?v ro t on. the evont'th o nsidoralolo o em nt, of he; eari g bushina is necessary. thatis to s me five to twenty thousaud hs, o an lnch befo e r at na the sha t sqll mi ted, mar e es ra le. torever the clampi g em nt. andmove bearinahushine 4 out ard y, a ter som moveme t haseonao cor ed t earing bushing .2 t also e pp cia d th t iusteadofyaeg ying the g ssu e to the lower end of th sha t; 84.5 shown in F518,; 5, a recessed die may engage framemfimhor- H and he sorsw engage th ssoddls, hus c usin bo h be ng, b s i a to. m r outw rdly at the omet m a F g, urther shows; n broken lines ano her t odf mov ng bearing-mem er Ahoutwardly its upporti g aeo turo tn ramo lo... 'lllthis ea e a bifuroatecle ome t 4 carried the amping m mber i l; and this lol uroated eloment engages the enlarged central portion 28 thus.

moves against the thrust-bearing surface of the bearing bushing, thus forcing the latter outwardly. It will be appreciated, of course, that some appropriate screw means will be employed for moving the bifurcated element upwardly.

In the bearing structure of the present invention, .as in other bearing structures for instruments of this general character, the reason for inserting the bearing bushings in the frameis that the insertable bushing normally is made from a metal which provides a better bearing surface than would the metal which is usually used in making the frames. In accordance with common practice, the bearing bushings are preferably made from relatively hard metal, such as stainless steel, whereas the frames are usually formed from brass. In all cases wherein the bearing bushing is made from harder metal than is the frame, the staking, splining, or other deformation, should be confined to the bearing bushing since it is the harder metal which must cut theslots or keyways in the softer metal. In cases, however, whereinit is desired to use a soft bearing metal, the deformation or staking is done in the frame member, as. illustrated in Fig. 7. In this instance, frame element it! is provided with an aperture for the reception of the bearing bushing H, and before the bushing is inserted in the aperture, the marginal edges of the aperture are upset at a plurality of spaced points adjacent to the outer surface of the frame member, as shown at 72. In this case, the oifset portions cut the splines or keyways in the bearing bushing, as is shown at E3.

By forming the splining or the staking on the K bearing bushing only adjacent to the inner surface of such bearing bushing, a shoulder is formed in the bearing bushing aperture as such bushing is moved outwardly. For heavy-duty work, this method of forming a bearing is desirable since the bushing cannot move outwardly beyond the point at which it has been moved by the application of force. In many relatively delicate measuring instruments, however, there is no considerable end thrust in the shaft, and accordingly the formation of the shoulder is not necessary. In such instances, the bearing bushing may be splined over its entire width, and then inserted within the bearing bushing aperture from either end thereof, and finally moved to its desired position by the application of pressure. Such a method is illustrated in Figs. 8 to 11, inclusive.

Referring particularly to Figs. 8 and 9, iii represents the frame element having bearing bushing aperture Tl which receives bearing bushing 78 which is formed with splines '19 over its entire Width. The bushing is formed with a bearing aperture 80 which receives the reduced terminal portion 8i of shaft 82. In following out this method, the bearing bushing is first inserted within the aperture and moved inwardly by any suitable means to substantially the position shown in Fig. 8. The frame may then be assembled with the shaft 82 in place. It is then only necessary to move the bearing bushing further inwardly to a point where its inner surface B l gives a desired measure of clearance to the shoulder 85 formed at each end of the shaft. This may be done by any suitable instrument, such as that shown in Figs. 8 and 9. This instrument includes a base 8'! upon which is mounted a vertical, bifurcated support 88 having a substantially U-shaped recess 89 extending downwardly from its upper end. The frame may be inserted in the position shown wherein the shaft projects through the opening, the opposed sides sf the bifurcated member supporting frame 13 against movement. Another vertical member 9!] forms a journal support for a screw element 9! having a thumb turn 92, the screw element carrying at its inner end a die 93having a recess 94. The recess provides clearance for the shaft, and the outer diameter of the die is less than the diameter of the bushing which the die engages.

It will thus be seen that as the screw element is rotated, bearing bushing 18 is moved inwardly to a point wherein its inner surface as approaches shoulder of the shaft. If a reasonable amount of care is taken, the moving of the bearing bushing can be stopped before the shaft is frozen, and, at the same time, provide a desired minimum of end play in the shaft. In some instances, however, the bushing may be moved inwardly toofar, and thus rotation of the shaft is prevented. In order to move the bushing outwardly to again free the shaft, the instrument shown in Figs. 10

and 11 may be employed. In this case, the bifurcated support 94 having recess 95 receives the shaft, the side walls of the opening engaging the inner surface 84 of the bearing bushing 18. In this instance, die at having a somewhat larger opening 97 than does die '93 is mounted on a. similar screw element 98, and as this screw element is manipulated, the die moves. the frame member in the direction of the shoulder 35 of the shaft, and thus moves the bushing outwardly relative to itssupporting aperture.

A number of preferred ways of carrying out the method of the present invention have been described herein, but it will be appreciated that the procedures are suggestive only, and that the method may be otherwise performed.

What I claim is:

1. The method of mounting a shouldered shaft in spaced frame members provided with aligned bearing apertures, and a bearing bushing in at least one of such apertures, in order to secure a predetermined amount of end play in the shaft, which method consists in forming, on the outer periphery of the bearing bushing adjacent to the inner thrust-bearing surface, a plurality of outwardly-disposed, offset portions which are adapted to cut keyways in the frame aperture as the bushing is moved outwardly therein, force-fitting such bushing into the aperture from the inner end of such aperture, assembling the frame with the inner surface of the bushing in relatively firm contact with the adjacent shoulder of the shaft, then, while supporting the frame member, caus-. ing the adjacent shaft shoulder to move against, the inner surface of the bushing, moving the same outwardly in its supporting aperture a sufi'icient distance to secure the desired amount of end playfor the shaft.

2. The method of mounting a shouldered shaft; in a frame comprising spaced frame members; provided with aligned bearing apertures, and a.

bearing bushing in at least one of such apertures.

in order to secure a predetermined amount of end.

assembling the frame with the inner surface of. the bushing in relatively firm contact with the:

adjacent shoulder of the shaft, then, while sup-- porting the frame member against movement, driving the shaft in the direction of such framemember, causing the adjacent shaft shoulder to movea-ainstvthe inner. surface ofv the; bushing, moving;=the samez'outwardly in its supporting.

aperture'sa-sufficient'i distance to secure the desiredI amount of: end play for the shaft.

3; In a.=measuring:instrument or the like providedlwithasshouldered shaft;a frame comprising spaced frame membersrformed with aligned hearing apertures fortheishaft, and a bearing bushing in one of such apertures, formed'with a plurality ofiproj (actions on :its outer periphery adjacent to itsiinnen. surface; the method of securing a predeterminedtamountof end'play'in the shaft which consistsrin forceefitting'suchl bushing, smaller end forward; into :its supporting aperture from the inner. endf-of;such aperture, thus forming a complementalrece'ss therein; limiting outward movementofasuch bushing, then assembling the frame and shaft iwiththe' inner surface ofthe bearing bushing -iniengagement with the adjacent shoulder-iofithe shaft, and finally forcing the shoulder of :the; shaft against the'bushing, while the adjacent frame member -is supported against movement-to move the bushing' outwardly in its aper ture -a sufficient' distance to secure the desired end play for the shaft;

In a measuring instrument or the like provided-with ashouldered shaft, a frame comprising spaced frame members formed with aligned bearing=aperturesfor'theshaft, anda bearing bushing in'at least one'of-such' apertures, the method of securing a pre'determined amount of end play in the shaft which consists in forming outwardlydisposed splineswir' the outer periphery of the bushing adj seem-, to its inner surface, force-fitting such bushing' into its aperture, thus cutting a shoulder- -therein,- limiting further outward movement, then=assembli ng the frame and shaft with the inner surface of the bearingbushing in engagementwith the adjacent shoulder of the shaft; and' then-"forcibly moving-theshoulder? of the shaft againstthe bushing, while the adjacent frame member is supported against movement,-

thus moving;the=:-bushin;outward1y in itszapefl" ture'a sufiicientidistancet-to secure the'desired "end-"- play. for 'theshaft 5; ln'a measuring'instrument or the like pro-- vided with' a shoulderedshaft, afranie: comprising' spaced:frame members' formedwith aligned bearing apertures for the shaft,' and a bearing bushingin at leastmnei'of such' apertures, the outer periphery of the'bushing bein'g formed with splines at a point-spaced inwardly from its outer surf ace;- the-method of securing a predetermined amount of end I play 'in th'e' shaft which consists in force-fittingsuch bushing into its aperture I from the inner end of such apertureg th'e splines-= cutting i shoulderswhereinf limiting further out ward movement -then assembling' the frame mem'- bers and shaft withthe inner surface of the hearing bushing in engagement 'with the adjacent shoulder of 'the shaf'ti and-then forcibly moving the shaft, by a micremetriescreW -drive;inthe direction of thebus'liiflg while the frame-member carryingthe bushing -is supported against move merit, thus causing? the shoulder-of -tfie "shaft to move the bushing outwardly: in its aperture a suificient distan'c'e to s'ecu're -tlie desired end pI-ay forth'e' 'shaft. v N

RIGHARDfl-Q N} WEINGART-L REFERENCES -GITED The iollowingirefrences are of record in the file of this patent 5" UNITED STATES' P-ATENTS

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