US2577819A

US2577819A - Screw thread tester

Info

Publication number: US2577819A
Application number: US637295A
Authority: US
Inventors: Short Frank
Original assignee: Individual
Current assignee: Individual
Priority date: 1945-12-26
Filing date: 1945-12-26
Publication date: 1951-12-11
Anticipated expiration: 1968-12-11

Description

Dec. 1l, l95l F, SHORT SCREW THREAD TESTER I5 Sheets-Sheet l Filed Dec. 26, 1945 Frm-LK E11-mrt @fw WMM/WMM Dec. 11, 1951 F. SHORT 2,577,819

SCREW THREAD TESTER Filed Dec. 26, 1945 3 Sheets-Sheet 2 Dec. 1l, 1951 F, SHORT 2,577,819

` SCREW THREAD TESTER Filed Dec. 26, 1945 5 sheets-sheet s :Frank 5h n r1;

Patented Dec. 11, 1951 o FFlcE.

SCREW THREADTESTER FrankShorhQanton (felglter, Gonn Application December 26, 1945, fSevriai No. 637,295

(Granted underw .the.1act of Marchf 3,' 1883, asA

The invention described herein may be manufactured and used by or for `the Government for governmental purposes, without the paymenttto me of any royalty thereon. i This invention relates to amachine for testin threads, both internal and external. In the meev chanic artsit is important, and in some situations of the utmost importance, that the threads 1 of the parts to be untied be free from imperfections ,orf irregularities such, for instanceVas ec,

centricity to the axis of thev part, or defect inf pitch, or any of a number of imperfections that..

occur in the fabrication of threads. The machine about to be described is designed to detect the slightest imperfections and/ or inaccuracies of the plates the provisionof an exact duplicate onpatf,v

tern of the perfect thread, but ofropposite hand' from the thread to be gaged, and rollingV thisopf' posite hand thread in engagement with .the thread to be gaged. The result of such action,

if the thread to be gaged is perfect, will kbe no i.

movement of the indicators, Whose operation will be caused by imperfections or irregularities of some sort, and in no other way.

For internal threads, a fractional size of a per-U feet thread is employed and placed in engage-` ment with the thread being tested,rbut in this, case the threads are of the same hand as those to be tested, and the pattern or perfect gage will have a pitch diameter a predetermined fraction of that of the thread to be tested, in order that the gage or pattern thread may .be moved into,A

and out of contact with the thread being tested.

In the drawings: Y Figure 1 is a top planyiew, somewhat scher; matic, of a machine for gaging both external and internal threads, including a partly broken away j shell or workpiece suitable forv illustration pur--Y lposes Figure 2 is a vertical section about on line 2-2 of Figure 1 looking in the direction of the ar-f rows; .v

Figure 2a is a fragmentary detail section ion line 2er-2a of Figure 1;

Figure 3 is a top plan view of a modification in.V cluding a fragment of theworkpiece and .showing amended April 30, 1928; 370 O. G. 757) the mechanismffor..engagir1g an `external thread; v `Figure 3a. is an 'end lelevation of the parts b5, tween the arrows 3cr-3a of Figure 3, looking thevdirectioniof the arrows; 'i 1 H V-`Figure 4 is averticalsection of Figure 3 about;

Figure 4a is a` wiring Y-.diagram`l appropriate .to thei operations offthe;mechanism; shown in Fig uresf3zand4';

Figure 5 is a side elevation of anothermodiifjl cation showing amechanism for gagllg anhinternalcthread;y y .A 'p f Figure 6V isan elevation partly Kin-section, of modified means for vrotating thewor1;piees, to compensate for differences V outside c liaqnetegrof the workpiece;

Figure fisa chart of typicalierrors .W

Referring L to Y. the drawings, and particulla 1,lv Figures 1^and 2 the n umeralwl` designates the.`` base of the; machine shown 'broken away for y economy. irrspace.4 `This will be properly .,SLIRPQFP: ed vaboveasuitable supportrupon legsZLFig. 2".

LNumeral.3;.des1gnates, aworkpiece.taillis 9 i a shell, .cylindrical for the most part, u and provid-3 ed with external threads 4 atoneendand inter?` nalthreads 5 atthe other. These threads areltne, ones tobe `testednor gagedfor imperfections of shape or location or both, obviously for, the purr-3,

showing" several indications 'pose of ascertaining whether they will `cactvpropf 1 erly and accurately with the threads of the other; elementto which theworkpiece is to bethreaded 1yv unted.- v Y 1 :The -shell ory workpiece is 4mounted for-true,

f-horizontal rotationuponits axis upon four` roll-yKV ers Bplmounted nponpshafts journaled in bracketsv secured to the base as shown in Figure 2.y I AAmo'tor i and a gear reducer 8 are provided -to give aslow rotation to the shell. These may be of anyfconventional1 type, andare mounted on thee upper end ofv a web 3v whose lower end is fase.A tened vtij-*ticeZ base I byv screws Aor other suitable J meses. J .y l

` "lhefrducer" provided with an inner `sleeve-V3 8j"; and ari'outesleeve 9 in'whichthe'slow speed shaft Illisjjour'naled.v A collar ll'is provided on'` the router endv 'of 4the shaft' and a gear wheel' I 2:v provi'ddwithfa boss 1 3' 4is mounted on the inner Securedzte thehaft bv; .Set SQIgWS; fhiuiitiej being; such-:thatend-,wise movement 9i ,the ,Sheik is prevented., V- I v y y y n.

A permanent magnet I`2' is secured to theboss- 65 I3l of. gearrwheel I 2, against which theshell or workpiece may be placed to rotate the shell at a desired slow speed without slippage.

Pivoted at I to a plate on the base I is an arm I6 whose upper end is provided with a bearing member I1 for a shaft I8 whose other end has a 5 bearing in an elongated gage member I9, xed to an arm t6 '(Figure"2a?', pivotedat I6"Vv to the base in the same manner as arm I6. By .thisil means, the shaft I8 may be moved in an arcuate path parallel to itself about the axis defined by1 1Q aligned bearings I5 and I6". The member I9 has secured to one side a gage havingal'polnter l 20 thereon, and a slidable spring backed contacti nger 2I. The opposite side of the dial member is provided with a lateral extensin-which has'a'l 15:

smooth machined face 22 for contact withthe i slidable finger 23 of another gage 24, similar to the gage 20. Gage 24 hasa pointerl 24'.. zThe. arm I6 has a lateral extension-W25' positioned somewhat above the base 4, and having an aper- 20 tu' therethroughfor-the. passage ".of `a bolt: 26 having ahead 21, whichserves asa stop to limit the counterclockwise rocking movementof. the arm I6 as viewed at Figure.' 2. ,.Interposedbef tweenthis extension 25 and thev base lI is a com- 25 pression spring 28, tending. torock thearm I6, arid consequently the shaft I8 and dial member away fromthe--slidable tlnger 230i the gage 24, mounted on a pedestal 29 secured at its.lower end to#theiaase-I---u w sl-M N i.

Slidably' mounted on theshaft .I 8 isthegaging... or testing wheel 30 formed with an integral sleeve 3Ito-mor`eeifectually guide the wheel in its longitudinal'emovements on thel'shaft, if thereshould befinJthee'tes'ting operation! occasionfor such 35 movements. This gaging wheel is @urged by l spring-2Bilinto--frictional engagementwith the Yexternal threads 4 of the shell or workpiece. 3as clarly sh'own in" Figure 1, and -its threads. are oil-'opposite Vhand from thegthreads 4. .The 'slid- .40 able linger 2I of- -the gage 20isin engagement wlthjthe outer smooth face of the gage wheel 30, s which-"face'lies inaplanenormallto'the axis of shaft' If'so--tha't itsmovement along the shaft I8, if' trireis -any,fduring the rotation ofA the shell. .45 will'ctuatefthe finger and consequently its piritrV The wheel-30 turns withthe external.. three/d4',` but in opposite"` direction, kand as `inti- .I m't'd, 'if th ga'ged or tested threads are accurateand in accordancewith requirements, there will be `no movement of the `pointer of gage 20, biititthe-thread 4 should -be eccentric to the axis i of the shell, an inward and outward movement@ will'beimpartedl to the/shaft I8 in parallelism witl'ltself-g and consequently there willbe a back `55 and "forth Vmovementof `the pointer of the gage 24, which movement, itv will beunderstood, will beV amplified to an extent to be clearly visible to the operator-and thereby inform him of themaccuracyof the thread.:y Now if, the pitch di- G0 ameter of the thread 4; is .greater or less than that speciedthere will be/'a slow longitudinal I movement of the wheel 30 on the shaft I8.. and the, pointer` of the'gage 20 willJ indicate the in-V perfection, so also 4will an irfacuate'-lad of 65 thread l4 be`indi`cated. Slol'd' the'thead'engagedhave an angularity with regard to the axis of'the"workpiece, a back and forth movement of the wheel 30,'"andconseduently the shaft I8, will". result, and' the imperfection will lbe indicated on 70 me gage-14;combination of errors in the thread k4-will bel indicated by afcombination' of movements of the dial indicators of botli'gages 20 yThe mechanism so far described gages or tests 75 external threads. and may be used for that purpose with or without the internal thread gaging mechanism to be described.

The bolt 26, Figure 2, extends through an aperture in the base I, where below the base it is secured to the outer end of a diagonally extending lever 3|" fulorumedfupon a'bar 32 mounted in ears 33 depending fromv the underside of the base. The reason for the lever and its closely associated parts will become apparent later on. A bolt 34 passes through an opening in the inner endo`f the lever and is held thereto by a nut, the bolt extending-upwardly through an opening in the base "and through an opening in an extension 35 integral with and extending laterally from an arm 36, corresponding to the arm I6. This arm 36`is`pivoted at 31 to a plate secured to the base. The bolt 34 is reduced in diameter to form a shoulder below the extension 35 and carries a washer 38', between which and the extension there.:is aspring 38.Y vA cotter pin (not shown) passesxthrough the reduced endA of bolt 34 to .t

maintain the washer in position. Rigidly secured to the upper end of the arm 36 is an elongated bearing member 39 in which there is nonrotatably mounted the horizontal shaft 39 upon s which the gage wheel 4I and its hub 40 are slidableI and which functions to test the accuracy of the internal threads 5 in the shell or workpiece 3.

vThis bearing member, like the gage member I9,

has aelateral extension 43 'with a smooth machin'ed face 44 for engagement with the iinger 45 ofl the gage 46 which carries the pointer 46'. This gage is monted on a pedestal 41 on the base I, as shown in Figure 2. Spring 38 surrounds headed bolt 34, and `being interposed between extensionv 35 andwasher 38 tends to rock arm 36 and` consequently bearing member 39 toward the gages46, and threads 4I .into contact with threads 5 so that rocking movement of the arm36, due to an'irregularityor imperfection in the internal thread 5r in the shell 3 sensed by the gaging threads 4I, will be imparted to the gage 46 and therefindicated by a movement of the pointer 46'.

Shouldit-be, for instance,Y that the workpiecethread is eccentric to theY axis of the workpiece, the' movement of the arm 36y will be inward and outward with respect to the axis of the shell, the the'V` movement of the arm 36 being precisely like that of the arm I6 which functions in connection with testing the external threads as heretoforee'scribed f The gage wheel 4I having threads, say exactly nine-tenths of the correct pitch diameter` of that of the workpiece thread 5, is mounted on the shaft 39 in such manner that it is free to slide axially thereon and also to move laterally parallel to itself, through the instrumentality of the spring-urged arm 36.

Avnormal thread 5, when the workpiece is rotated, will cause a continuous axial movement of the gage wheel 4I. This axial movement of the gage thread is compensated by the mechanism now-to 4be described. Y Integral with the hub 40 of the gage wheel 4I is an annular member 48 having side flanges 49 between which is an annular groove'50 which receives the ball 5I on the end of arm 52 of a lever 53 pivoted at 54 to a block- 55`slidably mounted in a frame 56 mounted upon a pedestal 51 whose lower end is secured to the base I. Mounted on the frame 56 is a gage 56'havl`ng a .pointer 58', and a finger or contact element 59 adapted to engage the block, there being springs 60 which urge the block away from the'dial' and toward a stop-6l in the frame, against Which stop the block'restswhen not actively en' gaged in its work. The other arm 62 of thelever 53 is traversed by a pin 63 which extends through elongated slots 64 in ears 64' integral with ay lon' gitudinal movable semicylindrical member 65. The' member 65 has a smooth, unthreadedinterior or concave `surface Vand isjheld inplace against threads 1'I or shaft 12 finjargvsuitablea manner such as by beingsplined on'shaft* 61 xed'" in standard 66 and aided to some extent, by rodwic 19. A second semicylindrical member 68 having@ internal threads, is pivoted orrshaft*Blfcrrslidf-g ing thereon as a unit with 'member 65.- Al/[emevv ber 68 is provided with a-lateral1extensionf9f Figure 2, adjacent its pivot;l whicha-'eicten'sion 1535 forms a seat for a tension spr'ing 2i'xiterposd between the extension and anfearorxthefstai'fion-v ary member 65 and tending to'u'rge' member 68 away from member 65, that is, away from thraded engagement with sha'it- 12. is. asbest shownhinFigure -rinternally ithreaded asfatll Iand coactsi-atftims -withi-tie threads 1P; (nr-horizontal shafftr-12 fnruntederotatably bearing-13 on standardf'66 adealt i-itsethe'i end ine-bearing 14 formed at the upper end of'a stand- 25 ard'15similar tothe standard'66;'botlstardards being -securely fastenedtcal base platt-#156 securedff tobase i. The standad'15is-indictedin-dettedlines /in Figure l, and-'needs nofurtherYifllust'ra` ments are to support the'fshaftv tance above the base if' f*- `IFast to the shaft-121is` a gearWheeln in mesh with the gear wheel SI2'y driven -by-" the-motor1 through the reducer 8. A lateral extensionlws :if

rod -is a 'spring 19 which. urgesthexsleeve-formed 461- byfthe members 65 and`68 toward -theend-ofthe shaft 12, the head on the rod 19-limiting-lthelout-i' Ward movement of the sleeve by engagementbea tween the said head and the extension 18. 'L'I' ther widened portion 8l fcrfsljidin'g-y eng-agemenawith the threaded member68= tof-iat; appropriate times# move' said member' Yover land against the ythreads 1I of the shaft 12 against the actionfof sp'rin'g-1`0-L 1 tocause movement of the-A 'sleeve onf-the shaft when the shaft'is rotated,A therebyVA torock-`the lever 53 so that the blocllz'wvillfoperatestliefiinf4 ger-59' of gage 58 toin'diatelth-elrigitudinalf uctuatonsbf thegaging-whe 4IH he :lever 4NIx has'- a narrow*handleJ82adaptedf-to' Y ""fe the other of two e shallow -notches'83 841 of a standard l86 mountd'cn? he ase "Ifto" hold member 68 in'orout ofengagenient with the threads of shaft 12A`as desired y `Inthe position shown the threaded'mmberl-GB66 isfY out of engagement Vwith thel `threadsilli'andA shaft*4 12, and cons.equently-`=tlie' sleevaz:'.Wmgnoty be' moved by the:rbtation-of'thshft; utiing thegaging'operationthesefthreadslwillibe e il* gagement andv v onfthe shaft at a ratecalclate'd 1pc- "corpe'nsate.flr for-the normal outward'ftra'velfof thegg' wheeli Ms when the thread 'tv of thewerkpieeefiseffect:v rect dimensions. `'Ihe 4mov'e'x'ne'rit'ofYthe sleeve is determined by thecarefulcalculationloftlie pi-tcf:l1*'70 ofthe thread onlthe` sh'aft312C tl-'ievptchd" ameters of gear# wheelsI iA y Wllfieril'the? sleevehas'freachedtliel'liinitc lits predetermined 1u te epen position inte recess so' behindaeshnreeeivetede thefsn'ftf' The member 68 20 arrivage1a?rr 6 der 80" of the lever 80 with the block v55 against thestopil. e

The numeral 81 indicates a plunger having an operating head 81'. A boss 88 on the base has an opening therethrough forV the plunger which plunger also passes through an opening-in the base -l with its lower end in position to engage the lever 3 l' to depressl one end of the leveragainst the influenceof the spring 28 andto simultane- 'ously raise the other end and release thetension of the spring 38, this operation being for the purpose of rocking and holding the gaging wheel 3|) away vfrom the shell or workpieceand also the gage wheel-4l v-away'f-rom the internal thread 5 of the work to permit withdrawal or insertion of the shell, as may be required. The boss 88 is provided with a bayonet-slot 89 coacting with a crosspin 86 to hold the plunger in raised or lowered position as desired.

The operation of the'mechanism thus far described has been indicatedto some extent' as the i description proceeded, but Vat the risk of repetition@ and for the sake o-f clarity,it -is summarized.;lv The gaging wheeli-30 turns. with'- thread# 4 but in# opposite direction. *vIff the desired factors oifthe gagedsthread` 4 are.. in accordance with theA re. quirement, `there will be no nmovement--ofi-thej indicators 20' and 24. If the thread 4 is eccentricV with respect to thel axis of--the work-or-shell 3,gshaft I8 will be rocked--or rscillated, -in-paral lelism with itself, withr'espect to the'axis ot-the# shelland an amplied oscillatory movement of the pointer 24 of dial24wifll occur.M I-f the pitch of -the thread` v4 is greaterthan or lessl than specified, therewillbe'a slow-lon`gitudinal movement in one direction or the-other ofi-the`A wheel 30 on the shaft which will-'be shown by'- the pointer 26 ofthe gage 20eSo'alsa-williai faulty lead of thread-4 be'shwn; A gagedr threadY having angularity offits axis will cause aback and forth movement of the Wheel 30,`which willi be shown on gage 20. Should there bea plurality# of errors they will be indicated by a combination@ of movements of the pointers of'b'oth' gages'.4

YForgagingoperations' `of the internal threadafi the gaging wheel Vfl'I-isplac'ed at"'thefinnerfend-' of the--threadr in the shell and the narrowe'end/ of lever 86 is moved over into inner notch 83 ofthe head 84, closing the member 68 againstith'efi threads of shaft 12 and holding it in such engagement. The rotation ofy the shell 3 willA now cause? gage wheel 4I tov moveslowly outwardly moving? the "sleeve formed yby''the'memb'ers 65 -an'd 6BV inwardly at the same rate soth'attheris-ne---f Hmoyementofthe pointer 58 ofthe-gage-", Tproviding the thread 5 is correct. If the 'shell thread has an incorrect lead, the pointer 58 will indicate thefault by a continuous lateral displacement.4 If-the axis of thread 5 is angular with respect to the axis of the shell, the pointer 46will show it@l byan oscillating movement. If theY thread 5 iseeccentric tothe center line of theshell, the pintera-f (2 s in.' nig.' yl i Tp-o fgrm hg gagwwlieel 'Mpls npr'oideleeeeiedipieierk .Whieesneebee wither? .ieler meeriteeeglenefeeeefeeh, t eegiegfby rthedirrn 99 of gage/member. |001`n which the shaft v fnlii1td`and.secured,"asffinstaric,by;` set sci-ewl'l'fIli's'iaftieis fixed izfmeinlgr f screwV v|l|2 and lcarries a gage 1073"4 plfeiiegwiih Hilger |06 iaeneeeemeflt .with ilie.` f eiaegeihe gege 4wheel .3.0, .and with @gelet-er. '93j Thefwier, end` ef tbeeege, member .l 09 vhee e. SmeQtb-.meehined .fece eesejgediby teenager U51. i aegee.- l, Hering, a pointer. |052' and; meunted- 0n the .yupperend Standard or vpedestal 401.. Seemed-t0 thebese; l ...-{Ilhearm 9| has two lateral extensions integral thexeivitlly;... ne\ |.98.; .tfthe= left.Ak and. 4the. other. |09, at the right as seen at Figure 4. A spring I|0 connected to the underside of extension |09 and to the base tends to pull the extension |09 over against an adjusting screw l|| in an internally threaded post ||2 on the base to thus move wheel 30 away from threads 4. The extension |09 is attached to the armature of solenoid |08 which when energized overcomes the spring ||0 and holds the wheel 30 against the thread 4 so that the threads of said wheel will properly engage those of the work. Suitably supported by attachment to a collar |50 fixed to a sleeve |5| of gage |03 is another solenoid ||3 whose armature ||3' is positioned to engage the finger |04 of the gage |03 under the influence of spring ||4. When the solenoid ||3 is energized, the armature is pulled away from the finger |04 so that it may function in the usual manner to indicate the longitudinal movement of the gage wheel 30 along its shaft 93 during the gaging operation. When solenoid ||3 is ie-energized,

armature ||3 is urged by spring ||4 into frictional engagement with contact or finger |04 to thereby hold the latter in any position to which it may be moved. Thus, at the completion of a gaging operation, wheel 30 is moved out of contact with threads 4 by pivoting its shaft 93 about the axis of shaft 89'. The wheel is then moved to its initial position to the right as viewed in Figure 3. This movement also moves finger 04 to the right and because of the action of spring ||4 and armature ||3, the spring-pressed finger is restrained from moving wheel 39 to the left until such time as solenoid ||3 is again energized. A solenoid arrangement like that justv described may be employed in connection with the finger |05 of dial |06.

The supply of electric current to the solenoids |08 and I3 is controlled by a switch 5 mounted on extension |09 of arm 9|, and carrying contact buttons |6 and ||1 engageable by a pin |I8, carried by the idler wheel 91. The ratio between the number of teeth on the pinion and those on the idler is such that a'given number of turns will be accomplished by the gage wheel 30 between the time the idler pin |8 presses against the button ||6 and the time it engages the button ||1. Obviously the pin ||8 may be adjustable or added pins may beV employed to control at will the number of turns of the gage wheel, and a number of turns below the maximum.

As may be seen upon Figure 4a, solenoids |08' and ||3 are connected in series with a battery |52 and a switch ||5.v This switch has buttons ||6 and ||1 which, when in the position shown, close the circuit. However, pressure upon either button acts to open the circuit through solenoids .r' al f. 1, l e staftortepdifl'nggopeaoa gear 91 'is in position sucli, i'lilljiiL-Tis l in contact Awith litten iii, and the" circuit is accordinglyvop'e 'Springfflthusacts to hold wheelzljfp'tgf centacfwith .the threads f workpiece onsupprting rollers 6 while armature I3 acts to hold finger |04.in retractedposition.' The workpieces nowrotated andfa's pin ||0 movesfaway from .button IIB, the latter nievesl euiwedlyrf w eleeei the Seleneid eifeit' .Enerf'r gizetie 0f Solegod |8.,ln0ves. Wheel -f 302.1999; engagement witl threads .4-.yhi1e eiiefeietiet. OffeQleeQie I liza-liberare. armature 'f 'I 'I3'- errer permite.I linger |04 te. meveinte @gesegnet-Wiebe thg''fceof WhekaarAf-ftr aupedermmdff number of rotations ot the workpiece and wheell 30, pin ||8 engages button ||1 and opensthe circuit. During the rotation of the workpiece, the gages |03 and |06 operate in the manner described for

gages

20 and 24, Figure 1. The rotation of workpiece 3 stopped as soon as button` ||1 is pressed inwardly, spring ||0 now acts to move wheel 30, out of engagement with threads 4 while spring ||4 acts to yieldingly fix finger or Y feeler |04 in position. The workpiece is removed, wheel 30 slid to the right, Figure 3, to initial position. This movement also moves fingerv |04 to retracted position in which position it is now held by, armature ||3' and spring ||4.- Switch |53 is opened, idler gear 91 is rotated to bringey pin ||8 into initial position wherein it holds button ||0 depressed, a new workpiece is placed. switch |53 is closed, and the cycle just described is repeated.- In the wiring diagram, Figure 4a, coils are shown corresponding to the solenoids |09' and |3. As stated, another solenoid, like ||3, may be included in the circuit with its armature engaging the nger |05 of the dial shown in Figure 3, all of the solenoids being energized and deenergized simultaneously by the closing or opening of switches |5vand |53, as previously described. v

Modification` Figure 5.-In this modification an arrangement is shown for testing an internal thread. There is a suitable base I9 upon which standard |2| may be secured and provided with roller bearings` 6 at its upper end suitably 4spaced to bear evenly upon and support the shell 3, which in this case is supported a substantial distance above the base. A shaft |22 is rotatable in bearings |23 and |23 on standards |24 and |25 secured to or resting upon the base H9.

Mounted on the shaft |22 and rotating with it, is a gear wheel |36 having a broad face so that gear I 34 may have ample movement axially of shaft |35 while remaining in mesh with gear |36. At the other end of the shaft |22 and beyond the bearing |23 is a gear |31, also fast to the shaft and meshing with a gear |38 of the same size and mounted upon the shaft of the reducer |39 mounted upon a pedestal |40, or upon any other suitable support, maintaining it at the proper elevation relative to the other mechanism.

The arm |3| may be biased toward thegage |28 by a spring 4| secured to an ear I5!) on the hub |32 and to an eye |5| onfthe base IIS, or by other suitable means, the requisite beingthat lateral iiuctuations of the arm will be indicated on the dial |28. In this form the thread engaging member 4| may be nine-tenths of the correct pitch diameter of the workpiece threads and is positively driven at the same angular speed as shell 3 so as to have some slippage with respect to the thread 5. The arrangement preferably is such that the gear wheel |38 drives the gear wheel |31 at a one-to-one ratio, and the broad face gear |36 drives the gear wheel |34 also at 'a one-to-one ratio, thus causing slippage between the gage wheel 4| and the internal threads -5. Bv this arrangement-the angular relation of -the threads 5 of the workpiece and those of the gaging wheel will remain constant rather than their lineal relations. So that the angular relation between the threads be not disturbed, I prefer to mount the arm `|3| carrying stud shaft |35 on which is mounted the gage wheel 4| and its hub and gear wheel |34', so that there will be no change in pitch diameter relationship between 4the gears |34 and |36. The gage |33 mounted on the gage member |30, which member is or may be a part of the arm |3|, will measure the axial movement of the gear |34', and the gage |28 mounted on fixed standard |21, will measure lateral movement of the arm |3|.

Slight differences in outside diameter of the shell or workpiece will affect the axis of rotation of the workpiece. To compensate for this I make the connection between the magnet |4| (Figure 5) and gear |38 (Figure 5) somewhat diiferent as will appear from Figure 6. In this form the magnet |4| which engages the end face 4 of the workpiece is provided with the hollow hub |42 of much larger internal diameter than the reducer shaft |43 to which the gear wheel |38 is fast. The magnet is mounted on the shaft by a plurality of rings |44, two in the present instance, of

resilient material, and the hub |42 of the magnet and hub |46 of the gear wheel |36, are each provided with intermeshing clutch teeth |48 between which there is some play, which with the yielding rings produces a positive drive with enough iiexibility, to compensate for slight offset of the axis of the workpiece with respect to the axis of the shaft |43.

In Figure '7 is shown a chart showing several indications 'of typical. errors. TIhecurves are plotted for time in revolutions indicated by characters 0-5 at the topl of the chart, for the abscissae and pointer positions as ordinates. The movement of the pointer of the dial 24 is shown in solid lines, the movements indicated by the pointer of dial `2|), being indicated Ain dotted lines. The combination of movements of the two indicators referred tov give distinctive indications of the several errors to be found andthe accumulations oferrors in. five or any desired number of revolutions maybe seenrat a point of l supporting the workpiece for true rotation upon f' its axis, means for rotating the workpiece, a gage wheel having perfect threads, the counterpart of .which is desired in fthe threads of the workpiece and engaging the threads of the workpiece, pivoted means mounting the gage wheel for lateral movement relative to the axis of the workpiece,

means mounting said wheel on said pivotal means for rotation and axial movement thereon, means associated lwith said pivoted means for norn'ially` urging the gage wheel into engagement with the threads of the workpiece, means carried by said pivotal. means mounting and in engagement with Isaid gage Awheel to visually indicate axial movement of said wheel, and means xedly mounted adjacent and engaging said pivoted means for visually .indicating the lateral movements of said gage Vwheel in response to the movement of saidpivoted means imparted by the gage.Whee1,.y i 2.- In amachine zforntestingfthe threads-of-a threaded workpiece for detection of imperfections inthe threads-,ofthe workpiece, means for supporting the workpiece for true rotationupon its axis, means for-rotatingthe workpiece,v a gage wheel having -perfect'threads the counterpart of which is desiredA on` the threads 4of the workpiece and engaging the threads ofthe workpiece and ing the gage Awl'ieelfor lateral movement relative to the axisL of thefworkpiece into and out of contact with the Ithreads thereof, means mounting .said gage wheel. on .s aid pivotal means for rotation on andsliding .along an axis parallel with theaxisof rotation of said workpiece, an indicator on said pivoted means and having a member engaging. the side of the gage wheel, saidindicator beingv responsive through said member to the sliding. movements of the gage wheel, anda second indicator adjacent and engaging said pivoted means thereby to indicate the lateral movements ofthe gage wheel.

, 3. In a machine for testing the threads of a threadedworkpiece, means for supporting `the workpiece for true rotation upon its axis, means for rotating the workpiece, a gage wheel having perfect threads thereon, the counterpart of which is' desired in thev workpiece threads, means for holding the gage wheel threads in close frictional contact with the threads ofthe workpiece, means mounting the gage wheel for longitudinal and lateral movement relative to thc axis of the workpiece, andindicator means for indicating said movements ofthegage wheel. y A

4. Ina machine for gaging the external threads of a threaded workpiece for the detection of imperfections in the.,workpiece threads, a gage wheel having threads the exact counterpart of those'desired in the workpiece and of the same pitch diameter and. adapted to frictionally engage the threadsof the workpiece, means for supporting the workpiece for true rotation upon its axis, meansjor ,rotatingA .the workpiece, means mounting-dimage@ whel. for longitudinal Vand latral movement in parallelism` with the workpiece mamar-9 fil axis, and meansfor indicating such movements of the gage wheel',Y i

5. In a machine for gaging the external threads of a threaded workpiece'for the detection of imperfections inthe workpiece threads, 1

a gage wheel having perfect threads, the counterpart of which is desired in the workpiece, means mounting the gage wheel for longitudinal and lateral movement relative to the axis of the 'workpiece means for indicating such movements, the threads on the workpiece and those p on the gage wheelgbeing opposite hand and of the same lead and pitch diameter so that when the threads are rolled in contact only imperfecj tions in the workpiece threads will cause longitudinal or lateral movement of the gage wheel Y and consequent actuation of the indicator means. 6. In a machine for gaging the threads of an internally threaded workpiece, means for sup- -porting the workpiece for true rotation on its 020 axis, means for rotating therworkpiece, a gage wheel having threads thereon the counterpart of which is desired in` the workpiecetthreads, said gage wheel being smaller in diameter than the threaded opening ofthe workpiece and of the 625 correct leadrand pitch diameter of the workpiece threads and in engagement with said threads, means mounting said' gage wheel for rotation and longitudinal and lateral movements, means for indicating the longitudinal and lateral move- U30 ments of the gage wheel, andconnections be- 'tween said indicating means and the gage wheel whereby said means is operated to indicate such movements upon the rotation of the gage wheel.

'7. In a machine for gaging the threads of -an L35 internally threaded workpiece, means for supporting the workpiece for true rotation on its axis, means for rotating the workpiece, a gage wheel having threads thereon the counterpart Vof which is desired in the workpiece, meanslil mounting said gage wheel for rotation and longitudinal movements, said gage wheel being smaller in diameter thanthe threaded opening of the workpiece and having threads o f the correct pitch diameter of the workpiece threads and in engagement with said threads whereby when the workpiece is rotated the gage wheel will be rotated andi moved continuouslylongitudinally in a direction'axially of the workpiece, a shaft rotatably supported in parallelismv with -the axes of the gage wheel and workpiece and provided with threads, a threaded sleeve engaging and moved by the threads of said shaft, c011- nections between the workpiece rotating. means Aand the shaft whereby the shaft is rotated in -timed relation with the workpiece, connections -between the sleeve on the shaft and the gage wheel constructed and arranged to subtract the axial movements of the gage wheel from the corresponding movement of the sleeve, and indicator means associated with said connections to indicate any difference in said movements.

8. In a machine for gagingH the external threads of a threaded workpiece for the detection Aof imperfections in the workpiece threads, means for supporting the workpiece for true rotation 'upon its axis, means for rotating the workpiece, a rockable member adjacent the workpiece and movable to and from the workpiece, a shaft mounted in said member in parallelism with the 'axis of the workpiece, a gage wheel rotatable and slidable onsaid shaft and-having perfect threads the counterpart of which is desired in the workpiece and adapted to engage the workpiece threads and rotatablethereby; said g'ag'wlie'el vbeing provided with an elongated pinion, al gage member fast to the shaft,,indicator meansfcarried by the gage member and'having a ngcr in engagement with the side of the gage -wheel and moved thereby to indicate the longitudinal movements of the gage wheel, if any, an idler gear carried by the Vgage member and in gear with said pinion and rotated thereby, an electrical circuit including a magnet adaptedwhen energized tourge the rockable member toward the threads of the workpiece, a switch in the circuit actuated by the idler rwheel to open and close said circuit; and spring means arranged to urge the rockablemember and-gagewheel away from the workpiece when the Vmagnet-is de-energized. --f' 9. In a machine for testing screw threads. means adapted to mount a workpiece for rotation about the axis of an internal thread ofsaid workpiece, aV hub having external threads of the same lead as said workpiece and a pitch diameter equal to a known fraction'of the corresponding diameter of said workpiece thread, means 'mounting said hub'for rotation on a second-axis parallel to saidr first-named' axis with said threads inengagement, a block translatable parallel with said axis, lever means pivoted on said block, `a pivotal connection between one end of said lever meansand said' hub, means pivoting the other endof said lever means in timed relation with the rotation of saidworkpieca and means'measuring any translation of said block as a criterion' of thelead of the threads of said workpiece.n Y Y l Y 10. In a'machine fortesting the threads ofa threaded'workpiece, means for-'supporting the workpiece for true rotation'upon its axis, means roperable to positively rotate the workpiece about its axis while so supported, aY gage wheel having circumferentially completel perfect threads the counterpart of which is desired in the threads of the workpiece, means mounting said wheel to engage the workpiece threads in pure tangential rolling contact therewith, for axial translation andfor lateral rocking movement toward andv from the workpiece about an laxis parallel with the axis of rotation thereof, and 4means responsive to axial translation and lateral rocking of said gage wheel to separately indicate suchmovements.

11. In a machine `for gaging the-threads of an internally threaded workpiece,- -means for supporting the'workpiece for VYtrue rotation on its axis, power-driven means-for rotating the workpiece, including` afirst A gear having operative yconnections with the workpiece, a first shaft mounted for rotation in Aparallelism withthe axis of the workpiece, a second gear on said shaft in meshwith said first` gear whereby said shaft is rotated in timed relation with the workpiece, an arm rockably mounted-cn said first shaft, a second shaft carried by said arm, a third gearslideably,and ratatably mounted on ,said second shaft `:and having an integraly hub,

a gage wheel xed on said hub and havingpervfect threads the `counterpart of which is desired 13 workpiece having a rst axis, said threads being supposedly co-axial with said axis, means mounting said workpiece for rotation only on said first axis, a shaft, means mounting said shaft in parallelism with and for movement toward and from said first axis, a gage Vwheel having perfect threads the counterpart of those required in said workpiece, said gage wheel being mounted for rotation and axial translation on said shaft, first gage means responsive to sliding of said gage wheel along said shaft, and second gage means responsive to change in separation of said rst axis and the axis of said shaft.

FRANK SHORT.

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

UNITED STATES PATENTS Number Number Name Date Johnson June 9, 1931 Hartness Nov. 3. 1931 Garms et a1. Apr. 18, 1933 Beardsley Dec. 19, 1933 Zerkle Jan. 7, 1936 McClure Mar. 4, 1941 Weinthal et al. Dec. 23, 1947 Johnson Dec. 30, 1947 FOREIGN PATENTS Country Date France Apr. 26, 1932