US3114991A - Sheet handling apparatus - Google Patents

Description

1963 AB FLOWERS ETAL 3,114,991

SHEET HANDLING APPARATUS 2 Sheets-Sheet 1 Filed April 10, 1961 Fig.l

J 2 /a on X 2 w I l E Q n INVENTORS Ab Flowersa I Donald $.Foote BY 2/.- WM

AGENT 1963 AB FLOWERS ETAL 3,114,991

SHEET HANDLING APPARATUS 2 Sheets-Sheet' 2 Filed April 10, 1961 I I n N? l l I I I I l l I I l I I l l I l II III... llll 7 3 a. n u u n 2 :uM- u u u u n h n T n x; u u a n f n n PX? LL 9 I. II I l l I l I l I I I I I I I I l I l I I I l I I I I I I l I I I i I I I I I I I I II. II F. H I III NQ Mt United States Patent 3,114,991 HEET HANDLING APPARATUS Ab Flowers, Beaver, P2 and Donald S. Feote, Greens Farms, Conn, assiguors to Crucible Steel Company of America, Pittsburgh, Pa, a corporation of New Jersey Filed Apr. 10, 1961, Ser. No. 191,742 3 Claims. (Cl. 5l277) This invention relates to an apparatus for handling sheet material preparatory to grinding and particularly, to an apparatus for securing metallic sheet material to a workpiece-supporting surface for grinding thereon. The invention also relates to sheet handling apparatus, particularly a novel crane-press, alone and in combination with a workpiece-supporting, vacuum chuck table, as an adjuvant in sheet grinding operations.

In the production of metallic sheet material such as titanium and titanium base alloys having extremely fine gauge tolerances, e.g., of the order of plus and minus 0.001 inch, conventional rolling procedure can be but an intermediate measure. Of necessity, some type of finish grinding must be employed. U.S. patent application Serial No. 798,889, filed March 12, 1959, now abandoned, of which this application is a contination-in-part, describes a particular grinding apparatus for obtaining the aforesaid gauge tolerances. This apparatus includes a disklike grinding head rotatable about a vertical axis with diamond cutting tools affixed to its lower surface and a workpiece-supporting table which is designed to pass underneath said grinding head during the grinding operation. The upper surface of the table, provided with a plurality of holes, grooves, or other cavities communieating with a source of vacuum and a tube-like sealing means about the periphery, constitutes a vacuum chuck, metallic sheet material when placed fiat thereon being held by atmospheric pressure. In the course of carrying out the grinding operation flat-stacked material is normally provided in a stacking area from whence individual sheets are drawn and transferred to the workpiece-supporting table. This seemingly simple operation presents no small problem when one considers that grappling hooks and similar lifting means if used to grip the edges of non-self-supporting, e.g., very thin, metallic sheet material will invariably cause buckling and warping. If the width to thickness ratio of the sheet is sufficiently large a bow or bend of such magnitude will develop that slippage will occur and the use of said hooks or similar lifting means will be rendered inoperable. Further, where a sheet is already warped or out-of-fiat or is rendered same by the transfer operation, the mere setting of the sheet upon the vacuum chuck table leaves much to be desired. Obviously, in such case the peripheral sealing means of the table will be ineffective to accomplish its intended function as the necessary continuous perimetric contact with the sheet underside will be lacking. The

sheet underside being accessible to the air, no vacuum will be created to properly secure the sheet, and upon contacting the rotating grinding head the sheet will be thrown from the table.

Accordingly, a principal object of the present invention is to provide an apparatus for transferring metallic sheet material to a vacuum chuck table whereby concomitant buckling and warping of said sheet material is substantially eliminated.

Another object of the invention is to provide an apparatus for effecting an hermetic seal between the underside of warped or out-of-fiat sheet material and the peripheral sealing means of a vacuum chuck table.

A further object of the invention is to provide a novel sheet handling apparatus comprising crane-press means for transferring and pressing metallic sheet material onto a workpiece-supporting, vacuum chuck table.

A still further object of the invention is to provide a novel sheet handling apparatus comprising, in combinas tion, crane-press means for transferring and pressing metallic sheet material onto a workpiece-supporting surface and vacuum chuck means at said workpiece-supporting surface for gripping said sheet material.

The above and other objects and features of the invention will be apparent to those skilled in the art from the following detailed description and the accompanying drawings which form a part of this specification and in which:

FIG. 1 is an overall plan view of a preferred apparatus of the invention as employed in a typical sheet grinding operation, the inventive crane-press, of the preferred vacuum type, being depicted in operable transfer relation to a vacuum chuck table and a grinding head, the latter shown in broken outline;

FIG. 2 is a top view of the crane-press shown in FIG. 1;

FIG. 3 is a side view of the crane-press shown in FIGS. 1 and 2 in operable sealing relation with a workpiece-supporting vacuum chuck table.

Throughout the drawings the same numerals have been used to denote the same elements.

Referring to FIG. 1, there is shown a vacuum cranepress 10 which travels on two elevated tracks 12 and 14 from its position in FIG. 1 to a position directly above a workpiece-supporting table or carriage 116. The table 16 is reciprocable on two guideways or tracks 18 and 2t and is adapted to move from its position shown in FIG. 1 to a position directly beneath a rotatable grinding head 22. In the course of the grinding operation metallic sheet material from flat-stacked piles thereof are individually transferred from their storage area under vacuum cranepress 16 to table 16 which, in turn, travels on tracks 18 and 243 passing under grinding head 22. As table 16 passes under the rotating grinding head 22 the grinding tools protruding from the lower surface thereof contact the sheet material carried by table 16 and secured thereto by a vacuum chuck and effect a correction or reduction in the gauge of said sheet material.

Referring to FIGS. 2 and 3, vacuum crane-press Ill includes an upper frame member comprising a pair of long transverse angle irons 24 and 26, interconnected by cross members 28, 30, 32 and 34 which are welded or otherwise securely fastened to angle irons 24 and 26. The ends of angle irons 24 and 26 are joined by members 36 (only one of which is shown) which, in turn, support axles 38 and ill extending across the length of crane-press 1th. Afiixed or keyed to the opposite extremities of axles 33 and 40 are wheels 42 which ride on tracks 12 and 14. Axle as is rotatably driven by motor ll which is connected thereto through gear reducer 43 and chain drive 4-5. Thus, rotation of motor 41 in one direction or the other will cause crane-press ill to transverse tracks 12 and 14 in either direction.

Extending between the central portions of angle irons 24- and 26 is an inverted channel member 44 which sup ports an air cylinder 46 and a movable frame 48. Frame 48 comprises a pair of angle irons 5t? and 52, interconnected by cross members 54 and 56. Angle irons 50 and 52 are, in turn, connected through linkages 58, 6t 62 and 64 to clevises 66 and 68 extending down wardly from channel member 4 The piston of cylinder 46 is connected through linkage 749 to channel mem ber 72 which is secured to the mid-sections of angle irons 5t and 52. Thus, cylinder 46 can be made to raise or lower frame 43 which is guided by the aforesaid linkages 53, 6t 62 and 64. Since the straight line distance between the ends of frame 48 and channel 44 will vary as frame 43 is lowered or raised, clevis 58 is pivotally connected to channel 44 by pin 69 to permit lateral move c3 ment of linkages 62 and 64 and thereby compensate for the aforesaid variation in distance. Depending downwardly from frame 48 are a series of suction cups 74 which are interconnected through piping 76 to a vacuumcreating means (not shown).

In the operation of the inventive apparatus crane-press evacuated through piping 76, and cylinder 46 is so prestopmost sheet in said stack. Suction cups 74 are then is moved by motor 41 to its position shown in FIG. 1 surized as to raise frame 48, suction cups 74, and :the adcups 7- 1- come into contact with the upper surface of the is so pressurized as to lower frame 48 whereby suction 74 into their elevated position. Thereupon, cylinder 46 is so pressurized as to raise frame 48 and suction cups which are to be ground. During this time cylinder 46 where it is directly above a stack of sheets or workpieces hering sheet '78. Thereafter, motor 41 is energized to cause crane-press 16 to traverse tracks 12 and 14, thereby transporting sheet 78 to a position over table 16. Cylinder 46 is then so pressurized as to cause downward movement of frame 48, whereby sheet 78 is lowered into the position shown in FIG. 3 where it rests upon the upper fiat surface 75 of table 16.

Table 16 comprises a base member 82 supporting a generally rectangular structure bounding cavity 86, said cavity 86 being linked by tube 88 to vacuum-producing means which may, depending upon requirements, be the same vacuum-producing means as that used to create suction in piping 76. workpiece-supporting surface 75 of table 16 is provided with a series of holes 98 which communicate with cavity 86 together with a tube-like sealing member 91 of rubber or other similar resilient material set in a groove extending therearound and near its peripheral edge, the arrangement being such that when sheet 78 is placed on surface 75 by crane-press 10', cavity 86 may be evacuated, whereby sheet 78 is held on surface 75 by atmospheric pressure with member 91 providing an effective seal for the edges of said sheet. Although a plurality of holes 90 are shown communicating with cavity 86 it will be apparent that grooves rather than holes may be provided in workpiece-supporting surface 75 with a relatively few number of holes connecting the grooves to cavity 86. It will be similarly apparent that workpiece-supporting surface 75 of table 16 may be subdivided into smaller sections by providing additional grooves therein similar to the one in which tube-like sealing member 91 resides, to accommodate sheets of various sizes In such case a continuous sealing member, of necessity shorter than sealing member 91, or an abutting separate sealing member, as depicted by cross sealing member 93, may be employed. Such subdivision will, of course, require vacuum cavity 86 to be subdivided or partitioned so that a resultant vacuum cavity will be formed adjacent tube 88 corresponding in permietric dimensions to that of the area circumscribed by the newly employed sealing member.

As will be understood, sheet 78 may be buckled or warped when placed on surface 75, thereby permitting air to rush under the edges of sheet 78 when cavity 86 is evacuated to preclude the creation of an effective vacuum in cavity 86. To prevent this result, means are provided on crane-press 10 for pressing the edges of sheet 78 against tube-like member 91 to thereby form an effective seal during the time that cavity 86 is being evacuate-d, the diameter and resiliency of sealing member 91 being such as to permit depression thereof flush with surface 75. The aforesaid means comprises frame 92 having an L-shaped cross section surrounding the outer periphery of sheet 78 above surface 75 of table 16 and being suspended from angles 28, 3t) and 32, 34 by a pair of hydr-aulic cylinders 94 and 96, said cylinders being connected to angles 28, 30 and 32, 34, respectively, by means of piston rods protruding from their upper ends and being connected to 98, 99 and 100, 101, respectively, at their lower ends, said angles 98, 99 and 100, 101 being connected to frame 92 substantially as shown. On the inside surface of frame 92 'at the intersection of its sides is a continuous tube 102 of rubber or other similar resilient material. Normally, frame 92and its associated tube 192 will be in the raised position shown by the dotted lines in FIG. 3. However, when sheet 78 is positioned on surface by crane-press 10, frame 92 and tube 102 are first lowered by cylinders 94 and 96 to the position shown in FIG. 3. This procedure seals the edges of sheet 78 against tube-like member 91 such that when cavity 86 is evacuated, an effective vacuum is created underneath the sheet which is then held on surface 75 by atmospheric pressure. Thereupon, frame 92 is elevated by cylinders 94 and 96, the suction produced by cups 74 is released, and frame 48 is elevated by cylinder 46. Obviously, the atmospheric force tending to hold sheet 78 on surface '75 may be increased for a given gauge pressure in cavity 86 by increasing the cumulative area of holes 90.

While the preferred apparatus of the invention has been described as embodying a crane-press wherein the gripping means are vacuum con-trolled and the pressing means are air pressure controlled, it is expressly understood that such means are to be construed as merely illustrative of the best mode of practicing the invention and not in any way as limiting the scope thereof. For example, the employment of mechanical or electromagnetic gripping means is contemplated as Well as the employment of mechanical or hydraulic pressing means. As to the use of electromagnetic gripping means, obviously such use is dependent upon the magnetic property of the particular sheet material to be handled. Where such use is availed of it is apparent that the transfer of individual sheets from a flat-stacked pile of sheets necessitates the introduction of insulative material therebetween.

Although the present invention has been described and illustrated in connection with a certain specific embodiment, it will be readily apparent to those skilled in the art that various changes can be made to suit requirements without departing from the spirit and scope of the invention.

We claim:

1. Apparatus for transferring sheet material from a fiat-stacked pile thereof to a workpiecesupporting surface provided with a plurality of openings therein adapted for connection to vacuum producing means comprising, in combination, a structure movable from a position above said pile to a position directly above said workpiece-supporting surface, first and second frame members depending downwardly from said structure and adapted to move in a vertical direction, the locus of points of the peripheral motion of said first frame member being within the locus of points of the peripheral motion of said sec- 0nd frame member, suction cups extending downwardly from said first frame member whereby said suction cups will come into contact with the upper surface of the topmost sheet positioned on said pile when said first frame member is lowered, means for evacuating said suction cups whereby said sheet will be elevated when said first frame member is moved upwardly, and resilient means on the inner surface of said second frame member adapted to form a continuous perimetric contact with the edges of said sheet and to press said edges against said workpiecesupporting surface when said second frame member is lowered whereby an hermetic seal will be formed thereby permitting effective evacuation of at least a portion of the area beneath said sheet to secure said sheet to said workpiece-supporting surface.

2. Apparatus for transporting sheet stock from a pile of sheets to a fiat surface provided with a plurality of openings therein adapted for connection to vacuunrproducing means comprising, in combination, a structure movable from a position above said pile of sheets to a position directly above said flat surface, a first frame member depending downwardly from said structure and adapted to move in a vertical direction, suction cups extending downwardly from said first frame member whereby said suction cups will come into contact with the upper surface of the topmost sheet on said pile when said first frame member is lowered, means for evacuating said suction cups whereby said sheet will be elevated when said first frame member is moved upwardly, a second frame member depending downwardly from said structure and adapted to move in a vertical direction, said second frame member having a substantially L-shaped cross section and being adapted to surround the periphery of a sheet held by said suction cups, one leg on said cross sect-ion extending horizontally over the surface of said sheet and the other leg extending downwardly adjacent the edge of said sheet, resilient cushioning means positioned on the inner surface of said second frame member at the intersection of its legs, and means for lowering said second frame member when a sheet carried by said suction cups is deposited on said flat surface by downward movement of said first frame member whereby said resilient cushioning means will hold the edges of said sheet against said first fiat surface during evacuation of said plurality of openings therein.

3. Apparatus for transporting sheet stock from a pile of sheets to a fiat surface provided with a plurality of openings therein adapted for connection to vacuum-producing means comprising, in combination, a structure movable from a position above said pile of sheets to a position directly above said flat surface, first and second frame members depending downwardly from said structure and adapted to move in a vertical direction, suction cups extending downwardly from said first frame member whereby said suction cups will come into contact with the upper surface of the topmost sheet on said pile of sheets when said first frame member is lowered, means for evacuating said suction cups whereby said sheet will be elevated when said first frame member is raised, and means for lowering said second frame member when said sheet carried by said suction cups is deposited on said flat surface by downward movement of said first (frame member, said second frame member being adapted to engage the edges of said sheet and hold them against said fiat surface during evacuation of said plurality of openings therein.

References Cited in the file of this patent UNITED STATES PATENTS 621,267 Monel Mar. 14, 1899 1,228,690 Monnet June 5, 1917 1,373,997 Debaeker Aug. 5, 1921 1,645,012 Kitchel et a1. Oct. 11, 1927 1,872,415 Crowley Aug. 16, 1932 2,204,207 Coburn June 11, 1940 2,413,554 Evers Dec. 31, 1946 2,443,987 Morrison et a1. June 22, 1948 2,451,920 'Clausen Oct. 19, 1948 2,467,172 Wheeler Apr. 12, 1949 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,114,991 December 241, 1963 Ab Flowers et alt It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 3, line 6, beginning with "apparatus crane-press" strike out all" I, to and including "heri'ng" in line 17, same column 3, and insert instead apparatus crane-press 10 is moved by motor 41 to its position shown in FIG 1 where it is directly above a stack of sheets or workpieces which are to be ground. During this time cylinder 46 is so pressurized as to raise frame 48 and suction cups 74 into their elevated position. Thereupon, cylinder 46 is so pressurized as to lower frame 48 whereby suction cups 74 come into contact with the upper surface of the topmost sheet in said stack. Suction cups 74 are then evacuated through piping 76, and cylinder 46 is so pressurized as to raise frame 48, suction cup 74, and the adhering Signed and sealed this 16th day of June 1964.

(SEAL) Attest:

ERNEST W. SWIDER EDWARD J., BRENNER Attesting Officer Commissioner of Patents

Claims (1)

1. 3. APPARATUS FOR TRANSPORTING SHEET STOCK FROM A PILE OF SHEETS TO A FLAT SURFACE PROVIDED WITH A PLURALITY OF OPENINGS THEREIN ADAPTED FOR CONNECTION TO VACUUM-PRODUCING MEANS COMPRISING, IN COMBINATION, A STRUCTURE MOVABLE FROM A POSITION ABOVE SAID PILE OF SHEETS TO A POSITION DIRECTLY ABOVE SAID FLAT SURFACE, FIRST AND SECOND FRAME MEMBERS DEPENDING DOWNWARDLY FROM SAID STRUCTURE AND ADAPTED TO MOVE IN A VERTICAL DIRECTION, SUCTION CUPS EXTENDING DOWNWARDLY FROM SAID FIRST FRAME MEMBER WHEREBY SAID SUCTION CUPS WILL COME INTO CONTACT WITH THE UPPER SURFACE OF THE TOPMOST SHEET ON SAID PILE OF SHEETS WHEN SAID FIRST FRAME MEMBER IS LOWERED, MEANS FOR EVACUATING SAID SUCTION CUPS WHEREBY SAID SHEET WILL BE ELEVATED WHEN SAID FIRST FRAME MEMBER IS RAISED, AND MEANS FOR LOWERING SAID SECOND FRAME MEMBER WHEN SAID SHEET CARRIED BY SAID SUCTION CUPS IS DEPOSITED ON SAID FLAT SURFACE BY DOWNWARD MOVEMENT OF SAID FIRST FRAME MEMBER, SAID SECOND FRAME MEMBER BEING ADAPTED TO ENGAGE THE EDGES OF SAID SHEET AND HOLD THEM AGAINST SAID FLAT SURFACE DURING EVACUATION OF SAID PLURALITY OF OPENINGS THEREIN.

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