US 3704015 A
Stiff flexible items, such as plastic credit cards, are inserted within four angled corner slits in respective mailer cards forming part of a burstable continuous form. A ram passes perpendicularly through a circular aperture in each mailer card and forces the credit card against a stationary anvil to bow the central section in a forward direction and concurrently cause the extended ends of the credit card to move rearward into contact with the mailer card to spread the slits. When the ram is retracted, the credit card, due to its inherent resiliency, snaps straight; as it does so, its four corners tuck into the slits around the aperture. Credit cards are mounted one or two to a mailer card automatically as they are advanced intermittently, first transversely of the continuous form to a merge position and then in the same direction as the continuous form to a mounting position.
Description (OCR text may contain errors)
[ Nov. 28, 1972 3,274,665 9/1966 Higginson et al. 3,330,581 7/1967 lvarrson- Wallerstrom........ 3,484,097 12/1969 Primary Examiner-Louis G. Manoene Assistant Examiner-J. A. Olifl AttorneyHanifin & Jancin and Henry E. Otto, Jr.
 ABSTRACT Stifi' flexible items, such as plastic credit cards, are inserted within four angled comer slits in respective mailer cards forming part of a burstable continuous form. A ram passes perpendicularly through a circular MOUNTING CARDS ON A WEB Inventors: Charles Holovka, Jr., Hightstown,
N.J.; Bohdan Demchyshyn, Levittown, Pa.; John Francis Mcl-Iugh, Fords, NJ.
Assignee: International Business Machines Corporation, Armonk, NY.
Filed: April 5, 1971 Appl. No.: 131,196
United States Patent Holovka, Jr. et al.
[ APPARATUS AND METHOD FOR 52 5 1 1 I Cl 3 5 39 00 aperture in each mailer card and forces the credit card 581 Field of Search ..270/52, 57; 40/104.12, 104.13; against a stationary anvil to bow the central section in 282/3, 115 A, 93/1 R, L1. 1 E 37 a forward direction and concurrently cause the ex- 235 tended ends of the credit card to move rearward into 13 Claim, 5 Drawing Figures contact with the mailer card to spread the slits. When the ram is retracted, the credit card, due to its inherent resiliency, snaps straight; as it does so, its four corners tuck into the slits around the aperture. Credit cards are mounted one or two to a mailer card automatically as they are advanced intermittently, first transversely of the continuous form to a merge position and then in the same direction as the continuous form to a mounting position.
.93/l.1 .29/210 X .40/104. 12 X .29/235 .93/1 R 291-453 X ode oooood ooecooo oo v 1 iiiiii i iiiiiiiiiiii 1 A References Cited Feathers......................
Porter..................... Thomas, Jr.
UNITED STATES PATENTS o w 5 n a m g MW v 4. MW i i P m Mm 2 3mv F MM m v a 3 ,2 111111 1 1 0 v M H M v 0 v 4 w m m L W n 3... 2 m .Tz h S I I HI I ,-----::f A w 0. O m M." m m n A l 0 no M Q m 0 I. M m x? mm H on n P 14 1 E awe/won CHARLES HOLOVKA,JR. BOHDAN DEMCHYSHYN JOHN F. MC HUGH BY 14M, 5 0/025), ATTORNEY PATENTED NEW 2 8 i972 SHEU 2 BF 4 PATENTEDHBY 28 I972 SHEET 3 [IF 4 APPARATUS AND METHOD FOR MOUNTING CARDS ON A WEB This invention relates to apparatus and methods for mounting small flexible sheets onto larger sheets for mailing or the like, and relates more particularly to an improved apparatus and method wherein stiff plastic credit cards or the like are mounted without adhesive to successive mailer cards on a burstable continuous form. I
BACKGROUND OF THE INVENTION It has heretofore been proposed to adhere credit cards to mailer cards burstable from a continuous form. This is undesirable because when the credit card is detached some of the adhesive will generally remain and cause the card to stick to whatever object it is placed against. Apparatus has been disclosed to insert items, such as watch crystals and film chips in bezels or laminated aperture cards, respectively; but such apparatus required that the insertion be accomplished solely by deforming the item to be inserted. For example, the film chip was deformed into a cavity in a punch by suction, then straightened by fluid under pressure to enter a peripheral groove around the aperture; but it required an undesirably expensive three-ply laminated aperture card to provide this groove, and so it was never commercially practical.
U.S. Pat. No. 3,484,097 discloses several embodiments of an apparatus to automatically insert tabulating cards successively into a series of four angled slits arranged longitudinally along a continuous form. The card to be inserted into the web is forced into an M-like shape (see FIGS. 5,6) while resilient fingers spread one set of slits in the web to catch the trailing comers of the sheet as the web moves forward. Then, further downstream other fingers push down on the leading corners of the sheet to tuck them into the other set of slits while the trailing end of the sheet is clamped by a plate and its midsection is pushed up by pins raised through a set of transversely spaced apertures in the web. It is readily apparent that this apparatus is exceedingly complex, even if it could operate satisfactorily to mount relatively stiff plastic credit cards.
In another embodiment (FIGS. 15,19) :1 pair of vacuum cups initially move down and suck the sheet from the web, and deform it into a concave anvil; then the anvil and cups move down together as a unit causing the corners of the sheet to spread and enter the slits while the sheet is still held by the cups; and finally the cups are disconnected from the vacuum source so the inherent resiliency of the sheet permits it to resume its normal flat shape and causes its corners to become fully tucked under the slits. Although this is considerably simpler than the first embodiment, it is nevertheless complex in that the anvil and cups must be movable both together and independently, and the operation requires four stages per cycle: viz, lower cups relative to anvil, then raise cups relative to anvil, then lower anvil and cups in unison, then raise anvil and cups in unison. Also note that the corners of the sheet are not forced toward the web and into the slits until the anvil and cups move down in unison and push the entire sheet toward the web.
There is a need for a relatively inexpensive and simple apparatus and method for mounting relatively stiff flexible items, like credit cards, to a mailer card or the like.
SUMMARY OF THE INVENTION Toward this end, and according to the invention, applicants have provided a continuous form web burstable into a series of single-ply mailer cards each with one or more sets of four angled corner slits that are inexpensively cut in the web around a single aperture centrally disposed within each set of slits. As a ram passes through each aperture, it forces a relatively stiff flexible card adjacent the aperture against spaced fulcrum points of a stationary anvil. The fulcrum points are closer than the end-to-end dimension of the caril, so the comers of the flexible card will be driven backward (i.e., counter to the applied force) against the mailer card and spread open the slits. Upon retraction of the ram, the corners enter the slits as the flexible card restores to its flat condition flush against the mailer card. A plurality of flexible cards can be mounted concurrently by providing a plurality of slit sets per mailer card and a corresponding plurality of rams; in such case flexible cards are serially advanced transversely of the mailer card to a merge position, whereupon the plurality are concurrently advanced longitudinally of the mailer card to mounting position and then simultaneously mounted.
Other objects and advantages will become apparent from the following more detailed description of the invention and from the following drawings wherein:
FIG. 1 is a fragmentary front elevational view, with the anvil portion removed, of a credit card mounting apparatus embodying the invention;
FIG. 2 is a left end view of the apparatus shown in FIG. 1;
FIG. 3 is a fragmentary plan view of said apparatus;
FIG. 4 is a fragmentary view, to enlarged scale and partially in section, of a portion of the apparatus shown in FIG. 3; and
FIG. 5 is a perspective view, also to enlarged scale, of the apparatus with the anvil portion removed.
DESCRIPTION As illustrated in FIG. 1, the card mounting apparatus embodying the invention comprises a card advancing unit 10 for incrementally advancing a series of cards 11, such as plastic credit cards, long edge down in a horizontal path into juxtaposition with a continuous card form 12 of burstable single-ply mailer cards 13 that are incrementally advanced in a vertical path adjaoent said horizontal path by suitable means including forms feed tractor pins 14.
More specifically, unit 10 comprises upper and lower guide rails 15,16 providing facing U-shaped channels for receiving the upper and lower edges of successive cards 11. These cards are fed serially into the channels 15, 16 by suitable means (not shown). Each time the leading edge of a card 11 strikes a microswitch 17, a single revolution clutch (not shown) is actuated to drive sprocket 20 to move an endless chain 21 a preselected incremental distance x leftward as viewed in FIG. 1. Chain 21 is entrained around an idler sprocket 22 and has a plurality of pushers 23 which contact the rear edges of respective cards 11 to increment them leftward said distance x. The pushers 23 project laterally into a suitable horizontally extending groove 24 provided in a backplate 25 that carries the rails l5, l6.
All cards 1 1 will have been inspected and found satisfactory prior to delivery to advancing unit 10. Hence, there will be no breaks in the sequence of cards 11. As the leading edge of a card 1 1 strikes a stop 26, it will activate a microswitch 27 to energize a clutch (not shown). This will activate a forms feed tractor 28 (see FIG. 2) to cause the tractor pins 14 which are entrained around tractor 28 and an idler 29 to drive the form 12 and hence mailer cards 13 upward.
As illustrated, form 12 comprises a series of singleply mailer cards 13 each having two identical horizontally spaced sets of four angled corner slits 30 and a circular aperture 31 centrally disposed within the area bounded by each set of slits. This configuration permits two cards 1 l (e. g., so-called Mr. and Mrs. credit cards) to be mounted side by side on each mailer card 13 defined between adjacent fold scores 32 and the conventional detachable marginal strips 33 that receive the tractor pins 14.
It should here be noted that two elongated slots 40 are provided through lower rail 16 to accommodate respective vertically movable card lifters 41. The upper flat edges of the lifters are narrower than the length of the respective cards 11, but normally aligned with rail 16. This is to supportthe cards 11 and maintain their lower edges horizontal because two slots 42 are provided through upper rail directly above slots 40 to enable the lifters to push the cards 11 upward from the merge position (shown by solid lines in FIG. 1) to the mounting position (denoted by broken lines). The slots 42 are only long and wide enough to permit upward passage of the cards 11 and lifters 41 so that the cards will be guided and retained by the walls of the slots as they are moved up to the mounting position.
Meanwhile, as continuous form 12 is moved upward by tractor 28, cards 13 will move past a microswitch 45. When switch 45 senses an aperture 31, a single shot half-revolution clutch (not shown) will be activated to rock a shaft 46 l80 (see FIG. 2). As shaft 46 rotates, it will act through an eccentric 47, a link 48 and a shaft 49 pinned thereto, and a sector gear 50 to raise a rack 5 1 that is positively connected to the left-hand lifter 41 (as viewed in FIG. 1). When the apparatus is being operated to insert two cards 11 concurrently, as illus trated, an electromagnetic clutch 52 (FIG. 1) is maintained energized to connect the rotated shaft 49 to the corresponding shaft 49 for the right-hand lifter 41 to cause its associated sector gear 50 and rack 51 (not shown) to raise said right-hand lifter in unison with the left-hand lifter.
As lifters 41 are concurrently raised by their respective racks 51, they will move respective cards 11 upward from their previously defined merge positions to their mounting positions. Meanwhile, form 12 will continue to move upward at substantially the same rate as the lifters 41 but behind backplate to assure that the cards 11 cannot become snagged in the mailer slits 30. As the eccentric 47 rotates to a position where it operatively drives the left-hand lifter 41 to the upper end of its stroke, it will operate a microswitch 53 to deenergize the aforementioned forms feed tractor clutch for stopping the tractor 28. This, in turn, will cause the form 12 to be stopped at its mounting position, defined by the apertures 31 in a mailer card 13 being coaxially aligned with respective rams 60 each forming part of a respective insertion unit, designated generally 61.
As best shown in FIGS. 2 to 4, each unit 61 comprises a negator-type constant force flat spring 62 that extends between spools 63, 64 and around a follower housing 65 to bias a roller follower 66 with a constant force against a cylindrical cam 67 eccentrically mounted on a shaft 68. Since each ram is coaxially connected to an associated housing 65, each spring 62 also biases the corresponding ram to a normal or retracted position, in which it is shown in FIG. 2. Each ram 60 comprises a curved end face 60a formed as a constant-width flat on a cylindrical portion that joins a square shank portion 60b. Intermediate its ends, portion 60b is coaxially connected to housing joumaied in a square bearing provided in a bearing block 69 to preclude rotation or twisting as it is moved axially.
With apertured mailer card 13 and the cards 11 in mounting position, the cards 13,1 1 are now above the separating backplate 25 and in intimate adjacent relation; but their non-adjacent faces are disposed with slight clearance between a mailer support plate 70 and an anvil member 71, respectively.
As best shown in FIGS. 3 to 5, plate 70 has a shallow recess 72 approximately the same size as card 11 but slightly deeper than the combined thickness of the cards 11,13. Recess 72 is directly adjacent the area of the mailer card 13 bounded by the slits 30, when the mailer card is in mounting position.
Each anvil member 71 has a concavely curved cylindrical surface 73, the direction of curvature of which corresponds to that of the curved flat end face 60a on the associated ram 60. Outboard of each end of recess 73 the anvil member is preferably relieved to provide two stepped shoulders 74, 75. The shoulders 74, 75 control the flexure of the card during its initial bowing and provide fulcrum points 76 where the shoulders 75 join the recess 73. These points 76 are preferably located so as to be contacted by portions of the cards outboard of any embossed or other indicia.
When eccentric 47 has rotated far enough to operatively drive lifter 41 and hence card 11 to mounting position, a mi-croswitch 80 (FIG. 2) will be operated to cause a single revolution clutch (not shown) to rotate shaft 68 and hence each eccentric cam 67 one complete revolution. As the rising part of each cam moves past the associated follower 66, the corresponding ram 60 will be moved rightward, as viewed in FIG. 2, slidably guided within its bearing block 69. Each curved end face 600 initially will move from an encircling hole 81 in plate 70 through the then-aligned aperture 31 in the mailer card 13 and into contact with the corresponding card 11 at substantially the geometric center thereof. As each ram 60 continues to move inward following initial contact with the card 11, it will force the card against the stationary fulcrum points 76 for progressively bowing the central portion of the card forward, as shown in FIG. 4, while concurrently causing the extended end portions 11a of the card (i.e., those lying outside the recess 73) to pivot elliptically at the fulcrum points and be deflected rearward toward the mailer card 13. As end portions are thus driven rearward, they will deflect and deform the mailer card 13 into the rece 72 in support plate 70 and, in so doing, cause the four angled corner slits 30 to be spread open.
As the high point of cam 67 (FIG. 2) contacts fol lower 66, ram 60 will achieve its innermost limit position, in which it is shown in solid lines in FIG. 4, and in which the card 11 has been bowed a preselected amount. By actual test, bowing of the order of 0.750 inch, as measured from the plane of fulcrum points 76 has provided excellent results when mounting plastic credit cards. As cam 67 continues to rotate toward its home position, at which follower 66 contactsthe low point of the cam, ram 60 will be retracted through hole 81.
Meanwhile, as the bowing force on card 11 is relieved, the inherent resiliency of the card will cause it to snap to a normal flat condition. This will cause the card end portions 1 1a to again pivot at fulcrum points 76, but in a reverse arc, and drive the four corners of the card 1 1 into the opened slits 30, thus completing attachment of the card 11 to the mailer card 13.
The lifters 41 are lowered to normal position by any suitable means as soon as the cards 11 are mounted on card 13. As illustrated, this is accomplished by the forward end of follower housing 65 striking and opening a microswitch 82 as the housing and ram 60 reach their rightmost positions as viewed in FIG. 2. Switch 82, after a slight time delay, operates the aforementioned single shot half-revolution clutch to rock shaft 46 a half revolution back to its normal position to operatively lower lifters 41 via gears 50 and racks 51. This completes a full cycle of operation of the card mounting apparatus.
It will be understood that the distance between the fulcrum points 76 and extent of penetration of each ram 60 will depend upon the dimensions of the card 11 to be mounted and its stiffness relative to that of the receptor 13 on which it is to be mounted. For example, for a card 11 of the size illustrated but not as stiff, the fulcrum points should be spaced farther apart but somewhat closer to the mailer card to reduce the width of the extended end portions and thus increase their stiffness so the slits may be spread open more readily. In any event, the card 11 to be mounted must be sufficiently stiffer than the receptor 13 on which it is to be mounted so that the end portions 11a will have the strength to deform the receptor and open the slits. The cards 11 must also have sufficient resistance to flexing to store adequate energy to snap quickly back to flat condition when the bowing force is relieved. To facilitate mounting of various types or sizes of cards 1 1, interchangeable or adjustable anvil members 71 may be used.
It will be noted that after two cards 11 have been concurrently mounted by the respective rams 60 and both lifters 41 are restored to their lower positions, switch 17 will be operated twice to advance the leading card 11 of the next pair into contact with the switch 27 that initiates a mounting operation. Cards 11 are delivered to rails 15, 16 at a rate slow enough to permit completion of a mounting operation between operations of switch 17.
It should be noted that in the embodiment illustrated. as the ram 60 moves in and pivots the extended portions 11a of card 11 rearward, the corners of the card will initially contact the web at points outboard of the slits 30. Then the card corners will move with a wiping action successively toward and then across and inboard of the tucking edges defined by the outboard edges of said slits. As the comers cross the tucking edges to the positions shown in FIGS. 4 and 5, the corners will push down on the web causing it to bend or crease along edges 72: (FIG. 5) of recess 72 and deform downward. The inboard edges of slits 30 are permanently deformed downward to open the slits and assure that the card will enter under the outboard edges of the slits when the bowing force is relieved. As the latter occurs, the portion of the web just inboard of the crease or bend acts as a cam surface or ramp guiding the short edges of the card as its corners tuck under the outboard edges of the slits.
While the apparatus, as illustrated comprises a pair of fulcrum points 76 defined by two parallel edges of concavely curved surface 73, it will be understood that, if preferred, there may be more fulcrum points; e. g., in the form of four protuberances inboard of the four corners of a rectangular card, in which case the card would be flexed or curled in both long and short directions by one or more rams having suitable end surfaces. Also, if preferred, the edges under which the extremities of the card are tucked may be defined by openings other than those provided by the four angled corner slits illustrated. But, as in the embodiment illustrated, the corners of the card when bowed must be forced inboard of the tucking edges so they can later expand via the openings and become tucked under the edges as the card resumes its normal flat condition.
It will also be understood that while the apparatus as illustrated is capable of mounting two cards 11 side by side, electromagnetic clutch 52 is deenergized when only one card 11 is to be mounted on each mailer card 13. Also since switch 45 does not initiate a mounting operation until it senses an aperture 31, the apparatus can without modification be used to mount cards 1 l at any desired longitudinal interval; e.g., every other fold or every third fold to provide a two-ply or three-ply mailer card instead of the single-ply mailer card 13 illustrated.
It will be apparent that the foregoing and other variations may be made without departing from the spirit, scope and teaching of the present invention. Accordingly, the apparatus herein disclosed is to be considered merely as illustrative, and the scope of the invention is to be limited only as specified in the claims.
What is claimed is:
1. A method of mounting relatively stiff flexible cards onto a web, comprising the steps of:
providing in the web at longitudinally spaced intervals at least one set of slits, each for receiving the extremities of a flexible card, and also providing an aperture within the area bounded by each set of slits,
advancing the web and flexible cards intermittently to bring successive flexible cards into juxtaposed position beside each longitudinally spaced set of the slits on the web,
bowing each juxtaposed flexible card by inserting a ram through the aperture and driving the card adjacent its short edges into contact with respective fulcrum surfaces to flex the central portion of such card between said surfaces away from the web and concurrently drive the extremities of such card outboard of the surfaces toward the web to successively distend the juxtaposed slits, and
withdrawing the ram to relieve the distending force on the web and permit each flexible card to straighten into retained relationship within the slits and tucked under the outer edges of the slits.
2. The method according to claim 1, wherein the web is a continuous card form burstable into a series of longitudinally spaced single-ply or multipleply mailer cards, and
each set of slits comprises four angled corner slits provided on successive mailer cards.
3. The method according to claim 1, wherein during the bowing operation at least some of the extremities of the card crease the web to permanently deform the area inboard of the tucking edges and provide a guiding ramp to facilitate. entry of the card under said edges when the bowing force is relieved.
4. Apparatus for mounting a relatively stiff flexible sheet within a plurality of slits on a larger sheet of less stiffness and having at least one aperture within the area bounded by the slits, comprising means providing spaced fulcrum points,
means for positioning the sheets in juxtaposed relationship with the fulcrum points at one side of the flexible sheet and aforementioned area at its op posite side,
means normally disposed at the side of each aperture remote from said flexible sheet, and
means for actuating the last-introduced means through each aperture into contact with said flexible sheet to force the latter against said fulcrum points for bowing the central portion of the flexible sheet forwardly between the fulcrum points while concurrently driving the extremities, including the corners, of the flexible sheet rearwardly against the larger sheet to deform it to open the slits for receiving said flexible sheet.
5. Apparatus according to claim 4, wherein said actuating means is operative to retract said lastintroduced means to cause said extremities of the flexible sheet to extend into said slits to detachably mount the flexible sheet to the larger sheet as the flexible sheet straightens under its inherent resiliency and the larger sheet is released from deformation.
6. Apparatus for mounting a pair of relatively stiff flexible sheets into respective sets of slits arranged side by side on a larger sheet of less stiffness and having an aperture within the area bounded by each set of slits, comprising means for advancing flexible sheets serially in one direction relative to the larger sheet,
means including a pair of members for moving a pair of flexible sheets concurrently in another direction generally at right angles to said one direction to position both flexible sheets flatwise immediately adjacent a respective set of said slits, and
means including a pair of rams movable concurrently through the respective apertures to contact and bow the flexible sheets and concurrently cause the extremities of said flexible sheets to distend the respective slits of each set to position said extremities for entry into the distended slits as the flexible sheets tend to resume their normal flat condition upon retraction of the rams.
7. Apparatus according to claim 6, wherein the larger sheet is a continuous web burstable into a series of sheets larger than a pair of flexible sheets, and including means for incrementing the web in said other direction to bring a pair of apertures into alignment with the pair of rams as the leading flexible sheet of each successive pair of flexible sheets is advanced in said one direction to a position in which both sheets of said pair are longitudinally aligned with a respective pair of the apertures.
8. Apparatus for detachably mounting a series of relatively stiff flexible cards into sets of four angled corner slits provided in a web in surrounding relation to apertures spaced along the web, comprising means providing at least one pair of spaced fulcrum points, one pair for each set of cards to be concurrently mounted,
means for advancing the web and cards intermittently to bring successive cards and sets of slits into juxtaposed position beside a corresponding pair of fulcrum points,
means including at least one ram per set of slits, for moving when cards and web are in juxtaposed position, through each aperture into contact with each juxtaposed card to flex it against the associated fulcrum points to concurrently bow its central portion forward and drive its comers rear ward for causing said corners to successively contact the web and distend the corresponding set of slits to position each juxtaposed card to enter the associated slits as it returns to its natural flat condition upon relaxation of the flexing force.
9. Apparatus according to claim 8, wherein said advancing means comprises separate means for advancing the web and cards through different distances commencing at different times and so interrelatecl that web and cards will move at substan tially the same speed to, and arrive at the same time at, the juxtaposed position to prevent the cards from becoming snagged in the slits.
10. Apparatus for tucking the extremities of a relatively stiff flexible sheet under a plurality of edges provided in a larger sheet by openings adjacent such edges, the larger sheet being of less stiffness and having at least one aperture within the area bounded by the openings, comprising means providing spaced fulcrum points,
means for positioning the sheets in juxtaposed relationship with the fulcrum points at one side of the flexible sheet and aforementioned area at its opposite side,
means normally disposed at the side of each aperture remote from said flexible sheet, and
means for moving the last-introduced means through each aperture into contact with said flexible sheet to force the latter against said fulcrum points for bowing the central portion of the flexible sheet forwardly between the fulcrum points while concurrently driving the extremities, including all corners, of the flexible sheet rearwardly against the larger sheet to retract said extremities inwardly of all said edges concurrently and so position the flexible sheet relative to the larger sheet that upon relaxation of such force the flexible sheet can straighten under its inherent resiliency and cause its extremities to enter under said edges via said openings for detachably mounting the flexible sheet to the larger sheet. 1 1. Apparatus according to claim 10, wherein said positioning means includes means for advancing a series of said larger sheets sequentially and intermittently in one direction to the juxtapose position, and means for advancing a series of flexible sheets sequentially and intermittently initially in a direction transverse to said one direction and then in said one direction to the juxtapose position. 12. Apparatus according to claim 1 1 wherein the respective means for advancing the larger sheet and flexible sheets in said one direction move such sheets at substantially the same speed to prevent the flexible sheets from becoming snagged in the openings during such advance.
13. Apparatus according to claim 10, including means providing a recess adjacent the aforementioned area of the larger sheet when said sheets are juxtaposed, and further providing at least one edge for causing bending of the larger sheet as a function of the movement of at least one of said extremities thereacross to depress it between at least one pair of said openings to facilitate entry of said flexible sheet under said edges in the larger sheet upon relaxation of such force.