US3636920A

US3636920A - Glue-dobbing and tray-forming method and apparatus

Info

Publication number: US3636920A
Application number: US832782A
Authority: US
Inventors: Paul F Bowman
Original assignee: Individual
Current assignee: Individual
Filing date: 1969-06-12
Publication date: 1972-01-25
Anticipated expiration: 1989-01-25

Abstract

A glue-dobbing apparatus for applying adhesive in controlled quantities to a paperboard blank and an apparatus for forming the glued blank into a carton are provided. The glue-dobbing apparatus is comprised of a glue tank which feeds glue intermittently through a solenoid valve to a glue fountain. One surface of the glue fountain is comprised of a resilient sponge which receives the glue from the solenoid valve. A plurality of glue spotters are adapted to contact the surface of the sponge under pressure to uniformly spread the glue within the sponge and conjointly remove a portion of the glue therefrom. The glue spotters are moved into contact with the blank whereby the glue carried by them is deposited on predetermined areas of the blank in controlled quantities. A tray former mechanism comprised of a mandrel and die cavity for forming the paperboard blank into a carton is also provided. The die cavity is comprised of an opening having a plurality of formers for folding the unglued sides of the blank to size. The cavity also has a plurality of plates to bend the glued sides of the blank upwardly which are placed to allow a small clearance opening between the mandrel and glued sides as the mandrel urges the blank into the cavity to prevent the glued sides of the blank from closing on the carton while the mandrel is in its cartonforming stroke. As the mandrel nears the bottom of its stroke, it contacts a moveable bottom plate which pulls the plates downwardly and inwardly on wedge-faced blocks to remove the clearance between the carton and the glued sides. At least 1,000 pounds per square inch of pressure is applied for approximately 1/4 second against the glued sides to force them against the carton to urge the adhesive into the surface of the paperboard to cause bonding of the glued and unglued portions of the blank. The mandrel is then moved out of the die cavity with the carton and the finished carton is then quickly removed from the mandrel.

Description

limited Mates howl/marl Primary ExaminerJohn P. McIntosh Attorney-Eyre, Mann & Lucas {57] ABSTRACT A glue-dobbing apparatus for applying adhesive in controlled quantities to a paperboard blank and an apparatus for forming the glued blank into a carton are provided. The glue-dobbing apparatus e se 9?? els t k h sh q s lvs in r;

at we 1r l5a I? as 58 mittently through a solenoid valve to a glue fountain. One surface of the glue fountain is comprised of a resilient sponge which receives the glue from the solenoid valve A plurality of glue spotters are adapted to contact the surface of the sponge under pressure to uniformly spread the glue within the sponge and conjointly remove a portion of the glue therefrom. The glue spotters are moved into contact with the blank whereby the glue carried by them is deposited on predetermined areas ofthe blank in controlled quantities.

A tray former mechanism comprised of a mandrel and die cavity for forming the paperboard blank into a carton is also provided. The die cavity is comprised of an opening having a plurality of formers for folding the unglued sides of the blank to size. The cavity also has a plurality of plates to bend the glued sides of the blank upwardly which are placed to allow a small clearance opening between the mandrel and glued sides as the mandrel urges the blank into the cavity to prevent the glued sides of the blank from closing on the carton while the mandrel is in its carton-forming stroke. As the mandrel nears the bottom of its stroke, it contacts a moveable bottom plate which pulls the plates downwardly and inwardly on wedgefaced blocks to remove the clearance between the carton and the glued sides. At least 1,000 pounds per square inch of pres sure is applied for approximately 5 1 second against the glued sides to force them against the carton to urge the adhesive into the surface of the paperboard to cause bonding of the glued and unglued portions of the blank. The mandrel is then moved out of the die cavity with the carton and the finished carton is then quickly removed from the mandrel.

6 Claims, 11 Drawing Figures PATENTEU M9125 i972 SHEET 1 (1F 6 9. 3 Q 3 9 mm ow H l ll 2w 2 o VG o H 5: 2 Q R 'l 0 h ll 0 om h an 3 mm 2 m. m s m a Q m on 3 N I? 5 mm .UHHHM Om v Q 3 m om o a .wxk 3 3 INVENTUR.

PAUL BOWMAN BY 7F flaw gfiu- ATTORNEYS PATENTEU JANZS 1912 SHEET 3 BF 6 ATTORNEYS PATENTED M25 r372 SHEET 4 BF 6 INVENTOR.

PAUL BOWMAN twig/ artw f w A TTORNEYS GL UlE-DUlliiBllNG AND TRAY-TURNING METHOD AND APPARATUS This invention relates generally to method and apparatus for applying adhesive to blanks and to fonning'the blanks into a complete carton. Prior art devices for applying adhesive to blanks have generally consisted of an adhesive bath and a plurality of transfer rollers to transfer adhesive from bath to blank. This method has proved to be unsatisfactory in that the transfer rollers build up a layer of dried adhesive thereon which makes control of adhesive deposition on the surface of the blank difficult. Periodically, the machinery must be stopped to remove dried adhesive from the rollers.

The method of adhesive deposition via transfer rollers is generally unsatisfactory in that the thickness of the deposited layer is not controllable even if the rollers are clean for reasons not completely understood. Adhesive layer thickness control is difficult to achieve with this method and it has never given truly commercially satisfactory results.

In accordance with the present invention, the above problem is overcome by the provision of a glue fountain having a sponge, preferably of sponge rubber, on one end thereof and means for transferring controlled quantities of adhesive from an adhesive supply or bath to the sponge, preferably the center thereof.

A plurality of glue spotters for applying adhesive to a surface to be glued are adapted to contact the sponge and apply pressure thereto to cause adhesive to transfer from the sponge to the spotter. The adhesive pressure helps spread the deposited adhesive evenly throughout the sponge. The amount of adhesive removed from the sponge depends on the amount of adhesive present in the sponge and the amount of the applied pressure. For best results, adhesive is intermittently fed to the sponge from the adhesive bath through a solenoid valve timed to release a predetermined quantity of adhesive into the sponge prior to the glue spotters contacting the sponge.

The spotters are generally made of metal, such as steel, and may be either solid or hollow. They may also be made of a suitable plastic material such as nylon. For best results, the spotters should have their sponge-contacting surface etched or crosshatched for more even distribution of adhesive upon the sponge-contacting surface of the spotter to achieve the best control of the adhesive layer thickness applied to the blank. The sponge-contacting surface of the spotter may if desired be a resilient material, such as rubber.

The adhesive used is preferably a water-based emulsion such as polyvinyl acetate or any of the dextrin family of adhesives. These adhesives generally set in about l30 seconds and become a hard film. A problem of major commercial importance with prior art adhesive deposition apparatus is that when the carton-forming machinery is stopped for any length of time, the adhesive bath quickly dries up and renders the machinery useless. To resume operation, a new adhesive bath must be installed and the complete adhesive deposition apparatus must be thoroughly cleaned. it has now been found that if the spotter of the present invention is left in cont-act with the sponge in a manner such as to seal the sponge from the atmosphere after the machinery has been stopped, the adhesive will not set and machine operation can be resumed even as long as a week later with no attendant adhesive setting problem and without the necessity for removing or cleaning the adhesive deposition apparatus.

in tray forming, the carton blank, which may be corrugated board or any suitable paperboard, varnished or unvarnished, is formed into the shape desired by a combination die cavity and mandrel. in prior art devices generally, the forming mandrel is of necessity made with external dimensions equal to the internal dimensions of the carton to be formed. The internal dimensions of the die cavity into which the mandrel pushes the carbon blank are generally made equal to the desired external dimensions of the finished carton. The mandrel pushes the blank into the cavity and forces the glued portions of the blank into contact with the unglued portions while the mandrel is in its carton-forming stroke. The camming action exerted on the adhesive by the mandrel and die cavity during the cartonforming stroke invariably destroys the fidelity of the deposited adhesive and squeezes it out and away from the area which is to be sealed. This often undesirably results in adhesive being squeezed out onto the mandrel or into the die cavity causing undesirable dimensional changes of these parts. In many instances, the excess adhesive squeezed out often results in the carbon being ripped during formation. Further, the amount of pressure applied to the glued areas of the folded carton to cause bonding is low because sufficient clearance has to be kept between the mandrel and die cavity to allow the mandrel and die cavity to allow the mandrel to force the blank into the die cavity. This inhibited the design of high-speed cartonforming machinery as the carton had to be held in its folded state in the die cavity by the mandrel until the adhesive had set i.e., at least about l5 seconds.

in an attempt to overcome the above problem, the mandrel and die cavity were slop fitted to permit folding without exerting a camming action on the adhesive. This resulted in a carton having rather large, generally undesirable dimensional tolerances. After formation, light pressure was applied and held for 10 to 15 seconds to allow the adhesive to set and bond to form. This also was inimical to the development of highspeed carton-forming machinery as the bond took too long to set.

These methods also proved unsatisfactory in that a highstrength bond was not achievable because the adhesive layer was generally too thick and subject to rupture in shear at low force levels.

In accordance with the present invention, the mandrel has external dimensions substantially equal to the internal dimensions of the carton to be formed. Portions of the die cavity are comprised of a plurality of plates which fold the adhesive-carrying portion or sides of the blank. The plates are placed to allow a folded clearance between the a.dhesivecarrying portions of the blank and the nonadhesive-carrying portions or sides of the blank during the major portion of the mandrel cartonforming stroke. Preferably, the clearance is of the order of l/ 32 inch or more and obviates the prior art problem of adhesive being cammed out from between surfaces during the mandrel carton-forming stroke. Near the end of the mandrel stroke, the plates are moved inwardly, preferably against wedge-faced blocks, to remove the clearance and high pressure is then applied to press the adhesive-carrying sides of the folded blank against the nonadhesive-carrying sides. In this manner, the camming action of the mandrel and die cavity of the prior art is avoided, the fidelity of the deposited adhesive layer is not destroyed and high pressures are applied to form a high-strength bond.

Should it not be desired to take full advantage of the above procedure, the high pressure alone maybe applied to urge adhesive into the blank substrate to form an extremely highstrength bond with existing dies and mandrels without the special die constructions described above.

it has been found that application of pressure in excess of 1,000 p.s.i. for as little as /8 second and preferably A mcond to the sealing area urges the adhesive into the substrate of the paperboard as long as the adhesive has been applied to an unvarnished portion of the paperboard. In the case of varnished paperboard, the adhesive used must etch the surface of the paperboard in order for the adhesive to penetrate. The application of pressures in excess of 1,000 p.s.i. for as little as a second not only urges the adhesives into the paperboard substrate but in so doing, leaves a thin layer of adhesive on the surface of the paperboard which assumes properties not unlike those of pressure-sensitive adhesive, thereby causing initial bonding even though the adhesive has not set. Commercially, this feature allows very high-speed carton formation not generally achievable before.

For best results, the layer of adhesive must not be decimated by the mandrel and die cavity as there may then be insufficient adhesive remaining to effect a substantial penetration of adhesive into the paperboard substrate and the remaining bonding layer may not be thick enough to give adequate strength. This problem is removed by the combination die and mandrel of the present invention. The adhesive layer must also not be thick enough to be substantially squeezed out of the sealing area under pressures in excess of 1,000 p.s.i. The adhesive layer thickness is simply determined by observing the formation of the tray into a carton by the mandrel and die cavity. If no adhesive is squeezed out onto the mandrel or into the die cavity, then the amount of adhesive deposited by the spotter on the blank is not too great. If the finished tray does not remain bonded, then the amount of adhesive applied should be increased but not above that amount which will permit adhesive to be squeezed out onto the mandrel or into the die cavity. The desired control of adhesive is readily obtained by means of the glue fountain, sponge, and spotter arrangement of the present invention simply by varying the amount of adhesive flowing to the sponge or by varying the spotter contact pressure.

As soon as the applied pressure is released, the mandrel is removed from the die cavity and the formed carton is removed ready for use as soon as the adhesive sets.

Any type of carton or tray may be formed by the above procedure regardless of the number of sides to be folded or the size of the finished carton. Also, cartons having closure flaps attached thereto may also be formed into open cartons by the above procedure, although the die and mandrel combination will not be able to fold the closure flap into its closed position.

The detailed description of a preferred embodiment of the present invention is directed to a high-speed machine for the purpose of illustration but the invention is not limited to a high-speed machine or to the particular embodiment of the invention herein described.

Referring to the drawings in which like numerals refer to like parts:

FIG. 1 is a schematic diagram of an apparatus embodying the principles of the instant invention.

FIG. 2 is an enlarged detail view of the fountain.

FIG. 3 is an enlarged view of a glue spotter.

FIG. 4 is an enlarged schematic view of another adhesive deposition apparatus.

FIG. 5 is a front detailed view of the mandrel-die cavity combination.

FIG. 6 is a side detail view of the mandrel-die cavity combination taken on line 6-6 of FIG. 5.

FIG. 7 is a top view of the mandrel-die cavity combination.

FIG. 8 is a detail view of the cam tumbler mechanism taken on line 8-8 of FIG. 1.

FIG. 9 shows a particular type of carbon blank in its justglued state.

FIG. 10 shows the carton blank of FIG. 7 folded with a clearance between glued and unglued sides.

FIG. 11 shows a finished carton.

Referring now to FIG. 1, there is seen an adjustable hopper 10 having a stationary wall 11 and a moveable wall 12 fixedly positioned via adjustable stops l3 and in which is carried a plurality of paperboard blanks 14. The hopper 10 can take various size blanks limited only by the provided adjustment range.

The paperboard blank 14 is fed by endless belt 15 to a normally open pair of nip rollers 16. Nip rollers 16 are then closed by air cylinder 17 to move the blank 14 to and through nip rollers 18 to position blank 14 against stop 19 at which point blank 14 is in position to receive adhesive. Metering gate 15a is positioned between hopper l0 and nip rollers 16 to prevent endless belt 15 from feeding more than one blank at a time.

Belt 15 operates intermittently via crankshaft 20 which is operated in turn by air cylinder 21. The belt 15 need only move blank 14 far enough to engage nip rolls 16.

When blank 14 is against stop 19, it is in the glue application position. Adhesive reservoir 24 which contains the glue is slidably positioned on shaft 25 for movement vertically to adjust the pressure head by which glue is removed from the reservoir and has a plug cap 26 thereon for adding glue thereto. The glue is preferably a water-based emulsion and for best results, polyvinyl acetate is preferred.

The adhesive reservoir 24 is positioned above a solenoid valve 27 to feed glue to the solenoid through flexible line 28 via the natural pressure head caused by the height differential between the glue bath and the solenoid valve. The glue feed may also be accomplished via a pressure tank type glue bath whereby the height differential between the glue bath and the solenoid valve may be eliminated. Solenoid valve 27 is intermittently opened and closed to release a predetermined amount of glue which flows under the pressure head via lines 29, which may or may not be flexible, into glue fountains 30 (See also FIG. 2). The solenoid valve is preferably opened once for each carton blank. An adjustment of the valve opening and pressure head may be made to control the amount of glue that is supplied to fountains 30.

Glue fountains 30 are comprised of a housing 31 having a mask portion 32. The mask portion 32 may have stops 32a mounted thereon, preferably Teflon, for reasons to be hereinafter described. Inside housing 31 is a block 33 preferably of metal, to which a sponge 34 of conventional construction, preferably made of rubber, or polyurethane, is mounted. The mask 32 holds the sponge in place against block 33 preferably without substantial compression of the sponge. Mask 32 may or may not be adjustable to increase or decrease the exposed sponge surface. A fitting 35 is mounted in housing 31 in communication with passageway 36 which is in turn in communication with sponge 34 on its upper surface and preferably at the center thereof for reasons to be hereinafter described.

Glue fountains 30 are slidably mounted on shaft 37 (FIG. 1) for movement to whatever position is required by the size of the blank and the location of the area to be glued. As many glue fountains 30 as there are separate areas to be glued on the blanks are used.

Glue spotters 38, shown in contact with blank 14 in FIG. I, are slidably mounted on shaft 39 for horizontal movement for proper positioning under glue fountains 30. Shaft 39 is mounted in bushings 40 which are fixedly attached to moveable platen 41 which in turn is slidably mounted on support bars 40 which are preferably four (two only shown). Moveable platen 41 is fixedly connected to a driven platen 43 via bars 44 (two only shown) the driven platen 43 also being slidable on support bars 42.

Driven platen 43 is moved upwardly by a conventional driving mechanism (not shown) and this in turn moves platen 41 upwardly which in turn carries support bars 40, shaft 39, and glue spotters 38 upwardly towards fixed platen 45.

Mounted atop moveable platen 41 is a block 46 to whichfis mounted a shaft 47 having a pulley 48 mounted thereon. Pulley 48 is connected via belt 49 to pulleys 50 mounted on shaft 39 and to reverse idler 50a (FIG. 8).

Pulleys

50 and 50a are approximately the same size as pulley 48. Shaft 47 is fixedly attached to tumbler 51, which has crank slot 51a therein. Follower pin 47a extends outwardly from tumbler 51 and is in turn slidably mounted to flat cam 52 in slot 54. Cam follower pin 53 is fixedly mounted to flat cam 52 and slidably mounted in crank slot 51a for reasons described below.

Flat cam 52 is hingedly mounted by bolt 55 in block 56 carried atop fixed platen 45 and is adapted to swing to and fro in response to upward movement of cam follower pin 47a in slot 54. Follower pin 47a is adapted to follow curved portion 57 of slot 54 and cam follower pin 53 is adapted to follow crank slot 51a in tumbler 51. As moveable platen 41 approaches fixed platen 45, flat cam 52 is moved outwardly to the right in FIG. 8 as determined by the leftward extent of curved portion 57 at which point cam tumbler 51 is rotated 180 from the vertical via rotation about shaft 47. Rotation of cam tumbler 51 causes belt 49 to move and rotate

pulleys

50 and 50a which, being the same size as pulley 48, are rotated a full I to rotate glue spotters 38 so that the faces 57 of the glue spotters are facing sponges 3 1i. Continued upward movement of moveable platen ill causes glue spotters 38 to contact sponges 3d, compress them to spread the glue carried therein throughout the sponge and to remove a portion of the glue carried therein. The amount of glue removed is a function of the amount of glue fed to the sponge 34 which is determined in this instance by the amount of time the solenoid allows glue to flow and the height of the upper surface of the adhesive in the reservoir M above solenoid 27. Other control means such as varying the compression of the sponge by the spotters may also be used.

The above-described motion is then reversed by moving slidable platen d3 downwardly to move glue spotters 3i downwardly to face blank M. Continued downward movement of the slidable platen 43 moves the glue spotters 38 into contact with blank ild whereby the glue carried by the glue spotters 3b is deposited on the blank.

Other means for rotating the spotters may be used such as a conventional tumbler having a cam track which rotates a spur gear, rack and pinion, clutch or airbrake, etc.

Glue spotters 3b are preferably made and may have their faces covered with a resilient material 58 such as rubber. The spotters 3b preferabiy have shoulders 3% to which stops Eiflb are mounted, the stops preferably being made of a nonsticky material such as Teflon whereby adhesive squeezed out of the sponge 341 by the spotters 3% will not adhere to the stops 38b. The stops 3tib are mounted such as to contact stops 32a on mask 32 to seal the glue fountain 30 to prevent adhesive from running out down and along the sides of the spotter. The resilient material 58 is preferably crosshatched (not shown) to more evenly distribute glue across the face of the spotter.

The faces of the glue spotters 38 may be separate from the main body thereof and mounted to the main body by conventional spring means (not shown). In this manner, the face of each glue spotter 33 will adjust itself to compensate any angular irregularity in the position of the glue fountain and any angular irregularity in the position of the blank.

The glue spotters 3% may be constructed to spot any desired pattern on the blank M. In the embodiment shown in the drawing, four glue spotters as shown in FIGS. 11 and 3 are used to spot the crosshatched glue pattern 59 as shown in the carton blank of HG. 9. The glue is deposited in each of four predetermined areas on the blank from which an open tray carton is to be formed as hereinafter described.

In sealing cartons with adhesive, it has been found that the fidelity of the deposited glue at 59 on blank 14 as shown in FIG. 9 is a factor in determining the strength of the resultant bond. More specifically, if the glue layer is of uniform character over the area in which the glue is deposited, a stronger, better and more uniform strength bond will be formed. Further, it is best to control the thickness of the deposited glue layer to no more than is necessary to achieve a bond and to prevent excess adhesive from being squeezed out.

Control of adhesive layer thickness is achieved by varying the amount of glue fed to the sponge 3 5i via solenoid 27 and by varying the height of the bath 2% above the solenoid, the amount of glue and its initial dispersion within sponge 3d is controlled. Also, the pressure exerted by the spotters 38 on sponge 3A distributes the glue throughout the sponge 341 and forces the removal of a portion of the glue onto face 58 of spotter 3ft, the amount so removed being a function of spotter pressure and sponge saturation. By controlling these variables, as little glue need be removed from sponge 34 as is necessary. Further, face 38 of the spotter, because of the uniform pressure exerted on sponge 34, will have a uniform pressure exerted on sponge 3 3, will have a uniform glue layer thereon for transfer to blank M. in this manner, the thickness, uniformity and fidelity of the deposited glue layer is controlled to achieve a bond having exceptionally high strength with as little glue used as possible.

in the preferred form of invention shown, the contacting surface of the glue spotters 3b is made to fit into the mask opening at the face of the glue fountain to seal the glue fountain from the atmosphere. A water-based emulsion glue as represented by the dextrin family or by the water-based emulsion glues are preferably used in accordance with the present invention. These glues generally set and] form a hard film after about 30 seconds of exposure and their use in the past has been severely restricted by this face since if the machinery is stopped for any length of time, the glue sets, rendering the machinery useless until the bath and transfer mechanisms are replaced or cleaned. it has been found that this problem can, for all practical purposes, be alleviated simply by leaving the spotters 3b in contact with sponges 3d after the machinery is shut down in a manner such as to seal the glue fountain from the atmosphere. The benefits of controlled glue deposition may be achieved in accordance with the present invention without sealing the glue fountain via the glue spotter and mask except that the benefit of preventing adhesive set up within the glue fountain during a period of machine shutdown will be lost.

After spotters 38 deposit glue at 59 on blank ll4l, stop 19 is rotated downwardly by air cylinders 11%. Nip rollers 60 are brought into contact with blank M by air cylinder bl to move blank M to stop 62 in edge guides (not shown) at which point the blank is in position ready to be formed in a carton.

in a modified arrangement shown in FIG. 4, the spotters 38 may contact sponges 3 i without rotation of the spotters as previously described but instead may be swung on arms from fountain 30 to hopper it) to deposit adhesive on the bottom of blank M while the blank is still in the hopper. This arrangement is especially desirable when the die cavity and mandrel are positioned below the hopper it) as would be the preferable case in a single-state machine where all operations on the blank are performed without horizontal transfer of the blank to various stations. Preferably, a conventional weight plate (not shown) is mounted on top of the uppermost blank in the hopper to apply pressure to the blanks to assure uniform contact of the spotters on the underside of the lowermost blank, in the modified arrangement. Also, more than one spotter may be used, there preferably being as many spotters and glue fountains as there are locations on which adhesive is to be deposited on the blanks.

Mounted on slidable platen lil is a block 63 which carries mandrel st. The mandrel n4, for the particular blank depicted in FIGS. 9-11]! is formed of two sidewalls 66 connected by a flat plate s7 in rigid relation thereto (FIG. 6) Mandrel 6d moves into and out of die cavity 68 as slidable platen an reciprocates, slidably platen All also moves the glue spotters 38 into and out of contact with the next carton blank.

Referring to FIGS. l and 5-7 and particularly FIGS. 5-7, the die cavity 6% is comprised of a pair of folding plates 69 mounted against wedge-faced blocks 7i] and a plurality of side-forming bars Ti, 72 (PEG. 7). Folding p'iates 69 have a groove 73 therein which is engaged by operating plate 78 for reasons hereinafter explained.

A pressure plate 7 3 is mounted on capscrews 75 which mount the pressure plate to shafts 7b. Shaft 76 extends through bumper 77 and operating piate 78.

As driven platen d3 is moved downwardly from its uppermost position, pressure plate 741 is positioned under blank M and exerts upward pressure thereon via. a spring (not shown) carried in block 911. As the driven platen 43 moves downwardly, it carries mandrel 6d downwardly to urge blank M into die cavity as. Blank 114i is urged into first contact with preformer plates 69a which starts the folding of the glued flaps and end flaps of the blank, the unglued sides being folded initially more than the glue flaps so as to position the unglued sides 79 inside the glue flaps b0. The blank M is then urged into contact with plates 69 and with forming bars 7 i which further fold unglued sides 79 and glued sides 80 of blank Ml further upwards. The forming bars 7ll. are preferably positioned slightly above plates 69 to assure folding of sides 79 first so that the glue areas 59 of the blank do not come into full contact with sides 79. Flaps 79a extend beyond fold lines Mia (FIG. 9) and are folded on fold line bite in front of the glued portion 59 by plates 69 as the mandrel is moved downwardly into the die cavity. Forming bars 71 fold sides 79 to an approximate 45 angle to assure folding without ripping by the mandrel during the initial part of the carton-forming stroke. Forming bars 72 complete the folding of sides 79 to a vertical position. However, it is not necessary to utilize a plurality of forming bars as described above and only one set need be used to fully fold sides 79 or conversely more than two sets of forming bars may be used.

Plates 69 are positioned during the mandrel carton-forming stroke to allow a small clearance 81 (FIG. 8) between folded

sides

79 and 80 as shown in FlG. 10. In the position shown, only the edges of flaps 79a are in contact with the glue areas 59 during the major portion of the mandrel carton-forming stroke to prevent the mandrel from destroying the fidelity of the deposited adhesive. To help achieve this, spring bars 84 are positioned between plates 69 to urge plates 69 towards wedge-faced blocks 70. Bolsters 85 are mounted on shafts 85a and can be moved forward and away from the die cavity as explained hereinafter but are positively fixed on shaft 85a via conventional means in the embodiment shown. Clearance 81 can be as little as 1/32 inch but for best results, is maintained at about A in.

As the mandrel continues its downward stroke, it forces ejector or pressure plate 74 into contact with rubber bumper 77 and operating plate 78. Operating plate 78 is then moved downwardly in cutouts 73. The downward movement of plate 78 causes plate 69 to move downwardly on wedge-faced block 70 and inwardly against the mandrel walls 66 to remove clearance 81 and press flaps 79 against glue areas 59. The rubber bumper 77 is provided only as a shock absorber to absorb the force of collision between the ejector plate 74 and operating plate 78 and is not essential to the operation of the apparatus.

At this point, hydraulic pressure cylinders 86 mounted between bolster plates 85 and wedge blocks 70 are operated to apply at least 1,000 psi. of pressure against glue area 59 urging the glue into the blank substrate. The pressure is held for not less than A; second and preferably for A second. The application of such high pressure causes the adhesive between flaps 79a and sides 80 to act like pressure-sensitive adhesives to cause a primary bond between flaps 79c and sides 80.

At this point, the hydraulic cylinders are deactivated to release the pressure and wedge blocks 70 are urged outwardly away from the formed carton 87 (FIG. 11) by springs 84a mounted between opposing plates 69 and by the upward and outward motion of plates 69 as the mandrel 64 begins to move upwardly. Additional assist is achieved by spring bar 84 which moves plates 69 apart during the upward stroke of the mandrel.

Shafts 76 are slidably mounted to driven platen 43 and move downwardly when the mandrel contacts pressure plate 74. Downward movement of shafts 76 urges air cylinder shafts 76a downwardly. Air cylinders 76b are of the normally retracted type whereby shafts 76a are always urged by air cylinders 76b to return to retracted position. Mounted to shafts 76 above moveable platen 43 is a stop 90 adapted to engage block 91 to limit the upward travel of the pressure plate 74 to a point approximately level with the underside of the unfolded blank. The shafts 76 are not moved upwardly by moveable platen 43 but are returned to their uppermost position by the upward movement of air cylinder shafts 76a. Stripper plate 91a is mounted to block 70 in conventional manner (not shown) and has an opening 91b therein for stripping the formed carton from the mandrel. A blower or conventional mechanical kicker (not shown) moves the formed carton horizontally to high-speed nip rollers 92 which quickly remove the formed carton from the carton-forming area. Slow-speed nip rollers 93 then remove the formed carton completely from the machine.

The apparatus depicted allows the mandrel and die cavity parts to be removed to accommodate different mandrels and die cavities depending upon the size and shape of the carton to be formed. Also, bolsters may be moved horizontally on shafts 85a and out to end plates 94 to accommodate the changed die cavity and mandrel.

it is intended to cover all changes and modifications of the preferred embodiments of the invention herein chosen for the purpose of illustration which do not constitute departure from the spirit and scope of the invention.

What is claimed is:

l. A glue-dobbing apparatus for applying adhesive to a surface comprising, a sponge, at least one spotter means adapted to contact said sponge and transfer a predetermined controlled amount of adhesive to said surface, means for moving said spotter means into contact with said sponge and said surface and means responsive to the adhesive transfer cycle for intermittently supplying adhesive to said sponge during said transfer operation.

2. The structure specified in claim 1 in which the means for supplying adhesive to said sponge are adapted to supply adhesive to the sponge at least once during each adhesive transfer cycle.

3. The structure specified in claim 1 in which the spotter means apply pressure to compress the sponge upon contact therewith.

4. The structure specified in claim 1 in which the spotter means and means for supplying adhesive to said sponge form an enclosure that inhibits the setting of the adhesive by atmospheric air.

5. The structure specified in claim 1 in which the said means for supplying adhesive to the sponge deliver the adhesive at the center of one surface of the sponge.

6. The structure specified in claim 1 in which the means for intermittently supplying adhesive comprise a solenoid valve.

Claims

1. A glue-dobbing apparatus for applying adhesive to a surface comprising, a sponge, at least one spotter means adapted to contact said sponge and transfer a predetermined controlled amount of adhesive to said surface, means for moving said spotter means into contact with said sponge and said surface and means responsive to the adhesive transfer cycle for intermittently supplying adhesive to said sponge during said transfer operation.