US2729040A - Vacuum chuck jigs - Google Patents

Description

Jan. 3, 1956 J. WALLACE ET AL 2,729,040

VACUUM CHUCK JICs Filed Feb. 1o, 1954 JAMES WALLACE NORLIN O. LEWIS IN VEN TORS ATTORN EY United States Patent Marietta, Gat assignqrs to BoeingY Airplane, Company, Wichita, Kans a cOrinrratiml of?` Delaware Application February 1`0, 195,4, Serial No. 409,479

5 Claims. (Cl. 51235) rlfhis invention relates to vacuum chuck jigs or the like for ixedly holding items of sheet-form, or` other work, while various operations are performed thereon.

Devices of this general character have long been used, for instance, in the plate glass industry for fixedly holding plane glass sheets during polishing operations. Apparatus of uthis kind, havinga permanently and predeterminedly curved work-supporting surface, has also been proposed for use in repetition manufacture where the sanding or polishing of sheet material is required, But l(he prior art does not provide a device as characterized wherein different predetermined curvatures of a workholding and sustaining surface can be produced; and it is the' priinary object ofvthis invention tofdo so.

j Thus the present invention contemplates primarily the provision of`a vacuum chuck or jig having a work-holding and sustaining surface whichv c an be readily adjusted'arnd sustained to conform` to the surface cntour of a particular piece of work, a heayy gauge pre-contoured ,airplane wing skin for example, so as to "securely hold same'while its ends are trimmed or milled or other operations performed.

' More specili'cally the invention contemplates in a device of this character the use of a spring metal chuckcarryipg plate which is so mounted and acted upon by adjustable means that it can be caused to assume a wide variety of different curyature-incorporating contours according to the contour of the surface of the work to be supported.

It is `also an aim of the invention to provide a device for the purpose indicated which is of simple, strong and durable construction, comparatively inexpensive to manufnture'a-nd requifresvno special skill to operate. The invention also resides in cer-tain novel features of, construct-ion, combination and arrangement of the various parts and in -rnodes of operation, as -will be understood and appreciated by those versed in the art upon reference to the now preferred example of the inyention shown the accompanying drawing in connection wit-h `the Idetailed description thereof to follow.

'ln the drawing, wherein the `same reference .charac- .ters designate the same` .parts :throughout .the several :vier/vs.- v

Figure 1 is a side elevational View fpantly broken and oartlfyin section @t one af the unitsemh Vas my rinvention, fit .being slated that several O f Same in lateral spesevmay he used .to support the airplane uWins skip `or otbe r-.wqrk;

.Figure .2 xis ,a sectional view taken on .the .line .of .Eiaure 31,;

,Figure ,3 ,is .apQrSneti-ve View partlybt011-ar1 partly .in section showing one Of the vacuum Chucks- Referring vto ,the drawing 'by reference characters, numera'l 5 indicates a heavy base plate having secured thereto at opposite ,ends the Ushaped brackets 6, 8, respectively. `Bloths =7 -secure the bracket 6 -to the plate 5 -wh'ile bolts 9 perform uthe same function vas to bracket 8,

'These brackets f6, 8 `have -the 'spaced Aupsta-nding arms FPlce 2v 6a,r8a,l respectively, and such arms pivotally support the opposite ends of a, flexible and elongated chuck-carrying steel platre 10. This plate 10 is adapted to be adjusted to, and sustained, in different archnformcontours by means of a series of basecanrried j ack screws to be referred'to here! inafter.l Y v i i In carrying out the invention, one end of the exible steel plate lll'has welded or otherwise secured theret'g the sleeve 1'1 through which extends the pin 12 Vwhoseen'tls are pivoted in the upper'portions of the bracket arms'G. The other end of the exible chuck-carrying steel'pla'te 10 is pivotally supported by the head of a 'T-bolt '14, there being sleeve elements 13 welded Ior otherwise xedly secured to"sad plate end at opposite sides of the 'lf-bolt stem 14a, as. suggested in Fig. 1l The ends of the T-bolt head 14 extend, beyond the outer ends of theA sleeve elements 13 to be guidingly retained inthe aligned andge'n'- erally horizontal slots v15 which areformed in the Yope posite arms 8g of the Ubr acket 8. i A

The stemI 14a of the Tfbolt 14 is threaded 14b, as indicated in Fig. 1, and slidably projects throughv an un# threaded guide hole 17 in the cross bar I6. This cross bar 16 is welded tothe opposed inner surfaces of 'bracket arrns 8a adjacent the rear top portions thereof, also as shown in Fig'. 1, *I

The threaded guide stem 14a of the slidably mounted T--bolt 14 has threaded upon its outer portionan adjustable nut or wheel 1S whose hub portion 181 is'adapted tobear against the outer surface of said cross bar "16 as shown in Fig. 1. Thus the adjustablemountingof the sleeved end 13`of the flexible steel plate 10 and'the`piv`- otal mounting l2 of its opposite end functions with'the jack screws 19 to enable said plate to be adjusted to,

v and rigidly supported in, a number of dilferent arch-form conformations when viewed in edge elevation as in l. Turning now to the jack screws 19, it will be noted -from an inspection of Fig. 1 that they are arranged in spaced series lengthwise of the base plate Scand vthe flexible steel plate 10 which they support.

rl`he jack screws 19 and associated elements being duplicates of one another, a description of one assembly will suffice. i c Y As shown in Fig. l, each jack screw 19 is provided at its upper end lwith a xedlyattached and preferably metal sustaining pad 20 which is engageable'with the underside of the flexible plate 10. The upper surface of each jack pad 20 is provided with ainotch 26A (Fing. 2) to clear the chuck anchoring studs or screws 28.

The lower end of each jack screw 19 is slidably received in the central bore 22a of a bearing member 22, whose lower end 22b is received in a holel 24 in the base pla-te 5. The bearing member 22 has a circumferential outstanding ange 23 which is supported upon the f'p surface .of the base plate 5, land screws 25 engaging ang'e 23 are provided to vsecure the bearing member Z2 to the base plate 5. Threaded upon each jack screw 19 is a conventional elevating nut 26 whose hub 26a bears against the .upper end of the bearing 22 so that when said nut 26 is turned 2in one direction the jack screw will be actuated upwardly. When the nut 26 is turned in the other direction fthe relatedjack'screw 19 will be forced downwardly into the bearing 22 through the action of the flexible steel plate 10, anditsload. 'i

Incidental reference has been made earlier herein to -the `work-engaging chucks 27 which are shown in tvFig. -l `as carried by the flexible steel plate V10 in longitudinal series with an intervening space between each chuck.

`One of these chucks 27 is illustrated in vperspective on an enlarged scale in Fig, 3, while lFig. -2 illustrates one lof said chucks in end elevation, the work and the flexible steel plate 10 being shown in cross section.

ln further carrying out the invention, I provide each chuck 217 with a depending lange 27a at each side to engage the proximate side edge of the llexible steel plate 1t) as indicate-d in Fig. 2 so as to prevent shifting of said chucks transversely of plate 1?. The respective chucks 27 aresecured to the flexible Steel plate l@ against longitudinal shifting by means of headed screws 28 which extend through said llexible plate l from the under surface thereof and into tapped holes 29 in said chucks 27 as indicated in Fig. l. The flanges 27a extend below the nether surface of the plate and receive the jack pads between them. The llanges 27a thus serve to prevent lateral movement of the jack pads, as clearly shown in Fig. 2.

The chucks 27 are of the vacuum-operated variety and detailed reference to same will now be made, referring particularly to the disclosure in Fig. 3 As shown, the chucks 27 are square although they may, of course be otherwise shaped. ln the illustrated embodiment of the chuck 27, opposite sides of the top portion provide the raised work-supporting llanges 3d. These work-supporting ilanges 3b parallel the depending spring-plate-engaging flanges 27a and are spaced outwardly from the endless top surface groove 31 which receives the vacuum sealing member 32.

The vacuum sealing member 32, which is of rubber or the like, provides the outwardly projecting wall and its widened base makes a snug tit in the chuck groove 31. The narrowed and flexible work-contacting outer portion 32a of the vacuum-retaining wall 32 projects, as shown, well beyond the plane of the work-engaging side flanges of said chuck. Thus, the space between the work-engaging llanges 3i) and the flexible vacuumre taining Wall portions 32a enables the latter to flex outwardly when forced into engagement with the work 41 so that the latter will be supported by the sustaining side llanges 3) of the chuck as indicated in Fig. 2.

Fig. 3 also illustrates that the chuck 27 has a central upwardly projecting rectangular boss 33 whose outer wall provides the inner wall of the vacuum wall-receiving groove 31. The outer end of the boss 33 terminates well short of the plane of the outer edges of the work-sustaining side flanges 30.

The waffle iron-like appearance of the outer end of the central boss 33 is produced by the intersecting air passage grooves 33a, 33b, which communicate with the vacuum-retaining wall 32 and with the central, and preferably shallow, clover form vacuum recess 34 in the outer end of said boss 33. The bottom 34a of the clover form recess 31 will preferably be substantially in plane with the bottoms of boss grooves 33a, 33b, as shown.

The bottom of what might be termed one leaf of the clover form recess 34 has the inwardly extending vacuum passage hole 35, the lower end 35a of which communicates with the vacuum passage 36. The vacuum passage 36 leads outwardly through one side of the chuck 27 and terminates in the threaded counterbore 37 for connection to the conventional suction line 33 which is indicated in Fig. 1.

The vacuum hole 35, 35a is shouldered adjacent passage portion 35a to support a layer of glass fiber or other filter material 4t) which prevents foreign matter from getting into vacuum line This iilter material is held in place by a screen-like grid 33 which is frictionally held in the enlarged inlet portion of hole 35 and seats on a shoulder as shown.

The suction opening or hole 35, 35:1 to the recess 34, while shown in a leaf formation of the clover form recess at one side, may be otherwise located and of course recess 34 may be of different shape. It will be understood that the intersecting surface grooves or passages 33a, 3319, of the waffle iron-like outer end of the boss 33 provide for the withdrawal of air from adjacent each of the vacuurn-retaining wall portions to the clover form vacuum recess, as heretofore noted.

The operation of the device will doubtless be understood from the foregoing description, but can be summarized as follows:

The heavy gauge airplane wing skin or other work 41 which has been pre-contoured is disposed upon the chucks of two or more laterally spaced units such as is shown in Fig. l. Then the jack screw nuts 26 are adjusted so that the jack screws 19 cause the llexible steel plate 1t) to substantially conform to the bottom work surface with the vacuum-retaining chuck wall portions 32a making firm and uniform contact with the work 41. When necessary the shiftable pivot 14 will be adjusted by moving the stop nut 13 inwardly or outwardly in reference to the cross bar 16 which is carried by the bracket arms 8a.

When the vacuum retaining wall ends 32a all make proper contact with the under surface of the wing or other work 41, the line 38 is put under vacuum to exhaust air from the space enclosed by said vacuum walls 32, 32a. This causes the work-sustaining walls 30 to be drawn into supporting engagement with the undersurface of the work 4l, the flexible outer portions 32a of the rubber vacuum retaining walls ilexing to admit of this action. The work is firmly held during trimming or cutting operations and is readily released by relief of the vacuum in the line 38.

Having thus described the invention, what is claimed is:

l. In a multiple vacuum chuck holder or the like, the combination of a base, a superjacent tlexible Work load sustaining carrier member, a series of work retaining vacuum chuck members detachably mounted on said carrier member, each of said chuck members having depending side llanges embracing opposite edges of said carrier member, bracket means pivotally supporting opposite ends of said carrier member and carried by said base, means operable to effect longitudinal adjustment of one end of said carrier member relatively of said base, upstanding jacks carried by said base and extending in a series lengthwise of said base and carrier member, carrier member engaging and sustaining heads ixedly secured to the upper ends of the respective jacks for varying the attitude of the carrier member, and a vacuum line having connection with said chuck members for electing the grip of the latter to the work.

2. In a multiple vacuum chuck holder or the like, the combination of a base, a superjacent ilexible work load sustaining carrier member, a series of work retaining vacuum chuck members carried in longitudinal series upon the upper face of said carrier member, base carried means pivotally supporting opposite ends of said carrier member, means associated with one end of said carrier member and its base carried means for effecting longitudinal adjustment of said carrier member end, and an upstanding and deformable base carried supporting means for said carrier member and arranged lengthwise of the latter, and a vacuum line having connection with said chuck members for etfecting the grip of the latter to the work.

3. The combination set forth in claim 2, in which said chuck members are detachably secured to said carrier member and have depending side llanges embracing side edges of the carrier member.

4. In a multiple vacuum chuck holder or the like, the

'combination of a base, a superjacent flexible work load sustaining carrier member, a series 0f work retaining vacuum chuck members detachably mounted on said carrier member, each of said chuck members having depending side ilanges embracing opposite edges of said carrier member, base carried means pivotally supporting opposite ends of said carrier member, means operable to effect longitudinal adjustment of one end of said carrier member relative to said base, upstanding individually operable jacks carried by said base and extending in a series lengthwise of said base and carrier member, the upper ends 0f said jacks engaging the under surface of said carrier member, and a vacuum line having connection with said chuck members for effecting the grip of the latter to the work.

5. A work holder comprising: an elongated flexible load supporting plate; individual means supporting the respective opposite ends of the plate; a row of jacks ar- 5 ranged lengthwise beneath the plate adjustably support ing that portion of the plate between the end supporting means, and adapted to selectively vary the attitude of the plate and to support it in a selected attitude; and a row of work-retaining vacuum chuck members secured in iuxta- 10 posed relation along the upper surface of said plate.

References Cited inthe file of this patent UNITED STATES PATENTS Semon June 16, 1953

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