US2827808A - Positioning table - Google Patents

Description

A. S. CHARLAT POSITIONING TABLE March 25, 1958 Filed Jan. 16, 1957 5 Sheets-Sheet l til.'

Y INVENTOR way s. MM#

BY Y ZW; Mmm/m y ATTO F! NEYf March 25, 1958 A. s. CHARLAT PosITloNING TABLE Filed Jan. 16, 1957 v 1 r l l l 'L LLV l March 25, 1958 A. s. CHARLAT 2,827,808

A POSITIONING TABLE Filed Jan. 16, 1957 5 sheets-sheet s FIG. 4

49 lo Les 47 55 5o INVENTOR f' uw JTM l I 5 ATTORNEY;

United States Patente() 'a POSITIONIIWIG l Arnold .schairlfgNm-wlk, than., assignormlwe su Inc.,"Est`Nrwlk, Conn.,` a corporation Iof Dela- Application January 16, 1957, Serial No. 634,482'- :"(Cl."f77``64) fIFhis-invention relatestotablesforpositioning awoif'k- V`piece beneath-and` inz diiferent relationsf-to the Lstool' fa machine," l'such-'as -the drill fofl a-dr'illing 'machine-for the cutter of a millingwmachinallso'?thatoperations Vcan'fbe performed onthe workpiece Vat'desiifedlocations. LAMore particularly, the invention isconcerned?with1'a-novel; positioning table forlthe; purpose stated,'-which includesa workpiece support having af free? translational movement within limits Vin:all directions in -a plane and lockingmeans for1 holding vthe fsupportfinlany' ofy a-#num'ber of predeterinztined.r positions in relatinto theltool iand'"engaging the 1 supportfrom t beneath and preventing itf'ffrom Ibecoming distortedby "the 'pressure 'applied' by ltlieftoblfto Qhefworkpieee .inlthe' machine operation. The new'tble has-features 'in-commonfwiththatiof the table'fof :my lpendingffapplication; Ser.. No.- 612,545; "filed :September 27, Y.1956,- but differs'ifrom the prior table infa' 'number 'of respects,l whichA willbel pointed out hereafter.

For. a vbetter!understanding ofthe invention; irefereiee may be made to the.iaccompanyingfdrawings,^in "which Fig. .1l-'is :aplan view oli-one form'of-'the'neW-table; bFigJfSZffis vaffr'agr'nentary end'elevationalV view"'f`the 'l ase;A l Fig. I3 fisial've'rtical sectional view fon' theif linef of Fig.1;

Pig. 4fis ia fragmentary Vvertical sectional `view Von" the linefS-S-of'Fig. 1, but o n-a largerscale thanthat ofFig'. .3; and

Fig ..5 vis= a view'lsimilar to Fig-4 jbut showingf'the workpiece support in a direntrelation `"to thdoeking lmea'ns.

The -new table in'the form shown in the j'dravvings'includes va base 10, fwhi'ch may be ametal-ca'sting f-generally rectangular shape 4having pairs ofspaced'paraliel yextensions 11,12ffrom its opposite ends. Eachextensioncarries a 'block 13` having `aY tongue-and groove' con- 'ne'ction -14 withthe extensionland lsecured'the'retoV by bo1ts"'1`5. Ea'chlbloc'k has lan openingfor 'receivingthe 'end Eof-a`rod fland'each rod extends between and-is supported in blocks 13"onaligned extensions 11, A12at opposite ends of base 10. The two rods lie parallel above thelitop of' the Abase and are'unsupported between their ends.

A `'carriage generallydesgnated 17 s mounted for movementalong the guide rods 16 and comprises a'cast- '-ing having apair oparallel passages V18 each"contain` ing a pair of ball bearing assemblies 19,`throu'gh' which one of the rods extends. vThe carriagelhas a centrall slot 20lyingmidwayebetween the rods 16 and'parallel thereto-andl thefslot isfdein'edy by a 1ip-20a`rising` above 'the -leveliof theitop'of thecarriage and having-af'fiat"top The-lcarriageis providedfwith pairs of spaced extensions 2L 22 vfrom it's opposite'en'ds lyingat right anglesto-ithe axis of slot'i20. vEach `oftthe'extensions '21,l 22"ca`r'ries a AblockZZSsecured:to the extension by screws242and having'fanfopening" for. .the endof a guidefrodfZS. The 'two :guiderodsfzsfextending betweenlbloeksfzs son alignedtensiensZIQZZ-lieparalleat rightanglesstorods 1'6; Tle

Av2,827,808 Piented Mar. 25, 1958 ,1.2 rddsffzseliealove the top sf/'the vcarriage17land-arefunl`supported'betveen their ends.

/A'-workpiece Lsupport `'generally designated 26 is mounted for movement onthe `guide rods 25 and com- 'prises- .af-casting having faat* topr and aligned'pairs of openings below `theV top and containingY-ballbearing assemblies 27. -`Aguidev rod extends through each'pairof vbearing 'assemblies andthe` carriage extends 4down`^be Y'tweeneth'e''roclsZS vand carries-'on -its Vlower end a location A1*:1tef28 provided with aplurality'of 'openings 29 extend- 'ing through vtlieiplate--and"of tapering form at their lower 'endsland ofl cylindricalf'format their upper. The loca- 'tion plate is'sec'r`ue'd=`to the -worlcpiece supportl by bolts 28a and isoriented'fin relationtothe support byjpins 30,

"31,5i-whichte'xt'end throughthefsupport and projectiabove Y-;'r`1id"bel; w= it. 'The lower ends of pins 30, '31'enter a'p'air of openingsy 29 Vinthe plate -28 and the upper ends' serve as 'rneansforfo'rien'tingiv a ywork-piece holder on the'support 126.-

lThe openings 29 in the location plate v28 receive means for locking fthe fplate 'and VVsupport Iin different positions "rlative to'the tool -and` such means include -apin 132 Vexte'ndingfthroughaLbushing "33- in an openingV throughs the top'of acap 34,` which-rests uponithetopk ofefa central lboss 35extend'i'ng upward from the base land -isf se'- cured iin'place' by Screws 36. The upper end of the vv"capext'eds'through the-slotZl) inthe carriage17 and-'lies inapproximately.the'plane-'ofthev top of the 1ip20tron thelcarriage. l"Alsof-the 'top of 'the capV normally lies spacedj from'the under-'surface of the plate" 28 by a clearlance-otra'fewthousandths of'eanfin'ch. The cap Y34"is hollow and provides cylinder 34a containing a piston''37 havinga peripheral groove containing'a rubber Oiring l3Sengaging'thefinner wall f "the 'cylinder and acting F'as affpistonsri'ng The' piston -hasa Acentral opening, 'throughfwhich the lowerl end of' pin 32 extendsp and be'arsaga'inst the underside offza Washer 39 seated against ashoul'der on the pin. A'washer 40 on'the pin-engages the'lun'der surface of thepiston and the assembly ofpistoni-and washers is vheld togetherandagainst the shoulder yon the' pin by a nut 41 threaded on'ithef' lower-end of the pin. A-'spring 42 vseated'atv its uppertend against the 'top of cylinder'f34a* bears againstthe top of'piston `3'7 and 'urges it downwardly. 4 v

Thepin '32 has a 'lengthwise' `bore withfa `chamber-"43 atits upper end containinga `ball 44, lwhich lismovable intoiand partly outA the chamber and is held inllplaceby the Ainturne'd outer `edge :of the pin lsurrounding "the chamber.- The bore through the pin leads tofa'chamber V45, which opens through the Vlower'end of the 'pin and w 'contains a valve disc 46 heldin place against the lower end of the pinV by'a nut-'47 threaded on`the1pini32 vformed 1with-a chamber`48 open through the lower end of the'lnut. 'Aballf'49 ywithin the chamber `ris urgedby a spring-50 to seatl against and closev the opening through valve disc 46. A rod 51 extends vthrough the bore through" the pin 32 andinto thechambers'43'and`45 and *the'vlength of the rod "isf such that, v'whenthe ba11'49lis seatd'on the 'valve disc 46 and the lowerend of the rod rests "upon the' top of the ball, the upper end of theV rod forces the ball44 'to'project out of chamber43. When ever the ball 44 is forced into chamber 43,` the l'ballno'rves `'the'rodSl downward to lforce the Aball 49 awayffrorn the valve'disc 46. A-spring '52'encircling the rod 51 'within'chamber45 engages a collaron the'rod and Vurges the rod upward.

Afpai'r'offchambers iead upward from the top of the'cylinder vv34a'a1`1d small'ibleeder passages "5311* lead fromfthe l'upperi ends of the respective chambers through thef'top rofthe cap" 34. V"Passages 54 'lead through the pin yfrornfchamber -45 into cylinder34a'labovefthe pistonv 37. Thefbessl' formed with a chamberiSS'open to"'cylin thepbottom of chamber 55. Y

In the use of the table described, a location plate528 kvis rst prepared by vforming a numberofopenings v29 corresponding in number and relative position'p'to the locations, where operations areto be performed on a workpiece in a holder resting y,on the ,support 26 and oriented by means of pins 30 and 31. V'l`he1plate is mounted on the underside of the support 26 and ori- `entedby pins 33 andV 31 and, when the'plateis in place,

air under pressure is admitted to chamber 55;v Ordinarily at this'time, Vthe upper ball 44 is in contact with the under surface Yof the plate 28 and is forced partially into the chamber 43, as shown in Fig. 5,Y so that the rod 51 holds the lower ball49 free of the valve discl 46. As a result, air from the chamber 55 ilows up through the valve disc 46, thechamber 45, and the passages 54 into the cylinder 34a above -the piston;37 and air escapes lfrom the cylinder through chambers 53 and the bleeder passages 53a. The sizeof the passages' 53a, the air pres- Y sure used, and the strengthV of spring 42 are such that,

when the ball 44 is in contact with the under surface of plate 28, the pressure of the air acting on top of the piston and theV force of the spring 42 are slightly over- Y l balanced by the air pressure beneath the piston, sokthat the piston and pin are urgedV upwardly by a light force. At the same time, the ball 44 is held against the under surface of the plate 28 by the force of the light spring 52 only and the upper end of the pin Vis out of contact with the plate.

When an'operation is to be performed on the workpiece, the support 26 is moved with the ball 44 rolling over the surface of plate 28, until the desired opening on the plate lies above the pin 32. As soon as this occurs, the pin is moved `upwardly into the opening and the ball 44 is free to move outwardly from its chamber 43, so that the rod 51 is moved up by the spring 52 and the ball 49 is seatedY on the disc 46 by the spring 50. The closing of the passage through the disc 46 cuts off the supply of air Vto theV cylinder 34a above the piston, whereupon the air pressure below the piston causes the piston to rise and the pin 32 is seated inthe opening in the plate 28 by the full air pressure and positively locksV the support in proper relation toY the tool. When the operation on the workpiece is completed, the air supply to chamber 55 is momentarily cut o, so that the pin 32 is withdrawn from the opening in the plate by the action of spring 42. As soon as the,v support V26 has been moved so that the pin and opening are out of register, theY air pressure is restored and the ball 40 bears lightly against the under surface of the plate 28. The support 26 is then moved to bring the next opening 29 into line with the pin 32 and the sequence of operations above described is repeated.

As above described, the guide rods i6 on the base and the guide rods 25 on the carriage are supported only at their ends and, when pressure is applied in a drilling operation to the workpiece in a holder on the support 26, the rods would bend downward, if nothing were done to prevent. Any substantial distortion of the rods under pressure during drilling would result in errors in the work but, in the construction described, the cap 34 lies directly beneath the tool and the top of the cap is spaced by only a few thousandths of an inch from the under surface of the plate 28. Accordingly, only a slight distortion of the rods Vunder drilling pressure applied to the workpiece causes the capto be engaged bythe plate 28 andthe cap and the b,ossr.3 5 on. the base-act as an Yabutment preventing any further downward. movement of the plate and the support 26. VThe air'issuing through the bleeder pipes 53a, when the pin 32 is not in an opening 29 in the plate 28, escapes through the clearance between the top of the cap and the under side of the plate and keeps the opposed surfaces of the plate and cap clean and free of small bits of metal, etc.

With the ball 44 making only light Contact with the under surface of the location'plate 28 as the workpiece support is shifted about to bring a new location on the workpiece into position, there is substantially no wear on the'platevand theplate may be made of relatively soft steel. This simplifies the operations involved in the for-Y mation of the plate and substantially reduces the cost.

l. A table for positioning aV workpiece beneath the tool of a machine, which comprises a base, a pair of parallel guides mounted on the base, a carriage mounted on the guides on the base for movement lengthwise of the guides, the,V carriage having anopening. lying Vbetween the guides on ,the base, a pair of parallel'guides mounted on Athe carriage and lying at right angles to the guides on the base, a workpiece supportmounted on the carriage guides for movement lengthwise thereof, means on the support for holding a workpiece fixed on the support in position to be acted on by the tool, the guides on the carriage being supported only at their ends and subject to down- Vward distortionunder pressure, a location plate attached to the under surface of the support in fixed relation to the holdingY means and having at least one hole in a position `corresponding to a location on a workpiece held by the holding means, anv abutment on the base having a top` opposed to the under surface of the location plate through the carriage and engageable by the plate to arrest downward movement of the support tending to distort the guides, and means, including Va pin projectable out of the abutment andadapted to enter thehole in the plate, for locking the support with the workpiece, thereon in a desired position relative to the tool. Y,

2. The table of claim l, in which the locking `means is provided with pneumatic operating means urging the pin out of the abutment with a pressure controllable by an element movably mounted at the outer end ofthe pin.

3. The table of claim 2, in which the element is a ball in a chamber at the outer end of the pin, theballbeing movable into the chamber bycontact with' the surface of the location plate and acting upon such movement to cause the operating means to urge the pin out of the abutment with light pressure.

4. The table of claim 3, in which the ball is urged out of its chamber by a spring and acts upon such move- `ment to cause the operating means to urge the pin out of Ymove the pin out of the abutment.

6. The table of chain 5, in which the pin is provided with a passage leading from below the piston to the space in the cylinder above the piston, a valve at the lower end .of the passage controls ow through the passage and is biased toward closed position, and means for opening the valve extend through the pin and are operable at the upper end of the pin.

7.V The table of claim 6, in which the valve opening Imeanscomprise a rod having its lower end in engagement with the movable member of the valve and a ball engaging the upper end of the rod and mounted movably in a chamber in the upper end of the pin, movement of the 5 means on the support for holding a workpiece xecl on the support in position to be acted on by the tool, a location plate attached to the under surface of the support in fixed relation to the holding means and having at least one hole in a position corresponding to a location on a workpiece held by the holding means, a pin adapted to enter the hole in the plate for locking the support with the workpiece thereon in a desired position relative to the tool, a mounting for the pin, pneumatic means acting on the pin and urging it into contact with the location plate, means for controlling the pressure with which the pneumatic means acts on the pin, and an element mounted at the outer end of the pin in position to engage the location plate and movable to regulate the control means.

References Cited in the tile of this patent UNITED STATES PATENTS 2,383,655 Johnson Aug. 28, 1945 2,674,139 Stern Apr. 6, 1954 2,742,801 Opocensky et al Apr. 24, 1956 FOREIGN PATENTS 253,762 Switzerland Nov. 16, 1948

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