NZ206569A

NZ206569A - Erecting cartons from blanks: bonding tackifiable blank parts using ultrasonic energy

Info

Publication number: NZ206569A
Application number: NZ206569A
Authority: NZ
Inventors: Juergen Heitele; Rudolf Kemmler
Original assignee: Fit Container
Priority date: 1982-06-02
Filing date: 1983-12-13
Publication date: 1987-10-30
Also published as: CA1211972A; ATE22844T1; FI834569A; DE8215958U1; EP0095628A1; DE3246325A1; JPS59120441A; FI834569A0; NO834589L; NO162408B; DE3366867D1; NO162408C; EP0095628B1; AU568322B2; AU2235383A; ZA839330B

Abstract

1. A method of producing prepared blanks (16) which serve to form collapsible boxes and which are adapted to be orientated in an apparatus (1) and of which the upright and respectively opposite parts (17) are to be connected to one another by adhesion, characterized in that on at least one of the two mutually opposite sides of the blank parts (16) which are to be connected to one another, a dispersion lacquer is applied all over or over only a part thereof, this dispersion lacquer which is applied to the parts of the blank and which has alrealy hardened out being rendered once again at least thinly viscous and thus adhesive when the blank parts (17) are aligned, by the action of ultrasonic waves and by the heating which is brought about thereby.

Description

<div class="application article clearfix" id="description"> Priority E>h12{s;: a-.R Complete Specification Filed: Class: .(.§h-v .8606&.{ PubUcetlon Date: ?. P. P^T. !??/. P.O. Journ?'. .Vc: ...J.^QL NEW ZEALAND PATENTS ACT, 1953 No.: f* I* rj, « Date: * *cm s» ' ^ 4~ D COMPLETE SPECIFICATION \0> ^ / ''PRODUCTION TOIl THE MANUFACTURE Or D LAN ICS ■ AND rOLDIMG CARTONS" Ch^oK^<m\rOCr hefwoD A^A^To/ X(/We, FIT CONTAINER AG, of CH-7000 Chur, Bahnhofstrasse 8, Switzerland, a Swiss corporation, hereby declare the invention for which Jc/ we pray that a patent may be granted to rn&Vus, and the method by which it is to be performed, to be particularly described in and by the following statement:- 1 (followed by page la) - la - JW569 The invention presented here concerns a process and a manufacturing procedure to erect carton blanks the printed surface of which is coated with a protective varnish and join together the erected parts facing each other. The manufacture of folding cartons from die cut blanks foresees the application of heat sensitive adhesive to those parts which are to be joined together immediately prior to introducing the blank into the erecting tool thus enabling one part to adhere to the other. Particularly during continuous manufacture and allowing for stoppages and faulty blanks the erecting mechanism inevitably accumulates a considerable amount of dirt which in turn leads to high maintenance charges. Should, however, the adhesive be applied to the blank earlier on, then special heating equipment would be necessary to re-activate the adhesive. Finally in the case of synthetic products of weldable material throughout, or material with a coating of weldable synthetic material, special hot air ^oots would be required to heat and soften the appropriate parts of the blank which are to be welded prior to guiding the blank in to the erecting tool. Quite apart from the fact that the steps outlined above are costly, they are also hostile to the environment and what is more require a considerable amount of energy to heat up the adhesive or parts of the blank. Furthermore the entire surface of the previously printed blanks is given a continuous coating of protective varnish to protect the blanks against mechanical damage and to improve the slipping properties during the erecting procedure. A dispersion varnish is used as protection varnish. O yC-* PtTSEPIW™ / - v- /; •f r 2 9^6569 The object of this invention is to avoid these drawbacks and to establish a method including suitable equipment which provides a simple and energy saving process for welding together the individually prepared blanks in a way that is also friendly to the environment. The solution to this problem lies in the following. At least one of the two sides of the blank facing each other to be joined together are coated completely or in part with a varnish of high solid content which simultaneously serves as protection varnish. As soon as the blank has reached the point of application at the consumer's plant it is run through a special erecting unit. The varnish applied to the blank is activated by ultrasonic waves which heat up the sealing area, thereby making the varnish at least tacky and thereby weldable. This method of joining the blank parts by using ultrasonic waves is the object of this invention. The dispersion varnish can cover the entire surface of the blank, serving as protection varnish for the printed area and as dispersion varnish for those parts of the blank which are welded together, all this in a single operation. No further operations are required. A perfect and clean weld is achieved. There is no surplus adhesive squeezed out along the edges of the weld which could smudge on to the carton. What is more, there is no need to allocate time for preparatory work when applying ultrasonic waves, as opposed to hotmelt and similar adhesives which need time to warm up, cleaning and other preparatory work. Accordingly in one aspect the present invention consists in a method for forming a carton from a blank in accordance with the present invention having sealing portions, said sealing portions having a coating resulting - 3 4 206569 from applying substantially in the form of a varnish sufficient thermoplastic solids in a liquid vehicle to enable on heating and cooling a thermoplastic bond between any particular sealing portion and that other part of the blank with which a bond is to be formed, comprising forming the blank substantially to its carton configuration, moving a source of ultrasound to each zone of overlapping of a sealing portion with another portion of the blank with which a bond is to be made and effecting said thermoplastic bonding using ultrasonics from an ultrasonic sound producing sonotrode with a flat face to heat the thermoplastic solids when pressing the zone of overlapping against an anvil surface with a plurality of discontinuous projections thereon, increasing the pressure at the weld and allowing at least some cooling to enable the bond or bonds to be created prior to releasing the formed carton. In a further aspect the invention consists in a method as claimed in any one of the preceding claims wherein said blanks have been die cut to provide a base, side, ends and overlapping flap elements, said method comprising: placing the blank over an open female forming die so made so as to define the corners of the carton base element, and in conjunction with a plunger to fold inward the sides, ends, and overlapping flap elements, pressing the blank into the said open forming die with said plunger having projections, bringing the flat face of a sonotrode against the outer of each pair of elements to be bonded with pressure sufficient to cause the projections of the plunger opposite to compress the said pair of elements in contact with each other, thereby reducing the distance between each sonotrode and the projections of the plunger at the welding interfaces of the pair of elements to be bonded, energising the sonotrodes to heat the "n £. N T bonding medium to at least a tacky state, 7 * ■ v *. £'; 4 - (MM* de-energising the sonotrodes while holding them under pressure against the outer surfaces of the formed carton until the bond has been effected, and withdrawing the sonotrodes to their initial positions. In still a further aspect in the present invention consists in an apparatus for welding the overlapping portions of folding or rigid cartons formed from flat blanks coated on at least one side of each pair of overlapping portions with a varnish containing thermoplastic solids, said apparatus comprising an anvil surface with a plurality of discontinuous projections thereon and an ultrasonic sound producing sonotrode with a N flat face movable towards the anvil surface to clamp the said overlapping portions between the sonotrode and the anvil surface with sufficient force to compress the overlapping portions in contact with the said projections on the anvil surface, thereby reducing the distance between the sonotrode and the anvil at the welding interface of the two overlapping portions, increasing the pressure at the weld, and forming an adhesive bond at each weld. In yet a further aspect the invention consists in apparatus for carrying out method of the present invention, characterised by at least one apparatus for carrying out the method according to any one of claims 1 to 11, characterised by at least one displaceably mounted apparatus for generating ultrasonic waves which bring about welding of the blank parts and which can be moved towards the aligned parts of the blank to provide an abutment therewith against the reaction of an anvil and then retracted again into the starting position. In still a further aspect the invention consists in a blank formable in to a box on apparatus in accordance with the present invention or by a method in accordance with the present invention characterised .in-thai. the i 517 SEP 1987 4+ - 5 - tM«•» blank is of cardboard coated at least at those locations which are to be bonded to one another with a hardened out dispersion lacquer which is capable of being rendered adhesive by the action of ultrasonic waves and the heating which is thus created. As far as the actual varnish applied to the blanks is concerned, the appropriate proportion of the ingredients would be approximately 40Z acrylic resin and approximately 60Z solvents which should preferably be water with an addition of ammonia. This varnish also has the advantage of high viscosity whereby the volume of flow measured with a 4 m/m DIN cup at ambient temperatures would be approximately 60 to 70 seconds. The application of this varnish to the various blanks or parts thereof is for all practical purposes best done by offset print. The quantity of varnish to be applied should be around 7-8 grammes/wet weight per M^. To assure a smooth flow of the varnish to the printing machine it is an advantage to keep it in a container fitted with an agitator and a pump preferably of the centrifugal variety. After the blanks have received the treatment outlined above they can be put through an autoplatten or similar machinery for die cutting in the usual manner and subsequently supplied in the flat to the consumer for further processing. To continue the process of this invention it is advantageous to use an appliance which is co-ordinated with the erecting tool on to which at least one ultrasonic unit is mounted to synchronise with the tool plunger and pressing against the carton flap to be welded whereby the piston of the unit slides out exerting the required pressure to the carton flaps to be welded and then immediately returns to its previous position. 6 If the blanks to be used are in part or throughout coated with synthetic material then the parts to be welded are heated by ultrasound at the connecting areas so that they can be welded intensively, particularly when the head of the ultrasonic unit is pressed firmly against the carton parts to be welded, whereby the plunger of the erecting tool inside the carton being formed acts as anvil. If on the other hand the blanks to be erected are made of uncoated board, then the varnish of high solid value having been applied to the necessary parts in the manner described heretofore is reactivated by the ultrasonic equipment and thereby made weldable. The effect of ultrasonic equipment can be further enhanced by providing projections on the parts of the plunger of the erecting unit which then serve as anvils being immediately opposite the ultrasonic units. This would increase the specific area pressure during the application of the ultrasonic unit. These projections can have either pointed or blunted tips. They can also be developed as shaped ribs which penetrate the board of the blanks which are to be welded, so that the distance to the head of the ultrasonic equipment is reduced thereby improving the effect of the ultrasound. Furthermore, it is of advantage if the appliance as outlined in this invention is equipped with a number of such movable ultrasonic units which should appropriately operate jointly and in pairs being positioned opposite one another. These ultrasonic appliances can also be moved pneumatically, and it is possible to adapt both the forward and retracting speed individually according to the circumstances by fitting rocker arms between the ultrasonic appliances and the pneumatic power unit. - 7 - 206069 Further details of the procedure according to this invention and its application are outlined in the following drawing showing an applied project as an example and the consequential claims as the outcome of this invention. The illustrations are: Fig. 1 Diagram of the equipment with blank fed in Fig. 2 Illustration according to fig. 1 but showing the erected blank Fig. 3 Application of the sonotrodes Fig. 4 A sector of fig. 3 on a larger scale Fig. 5 Heating interval and Fig. 6 Illustration according to fig. 1 showing a second blank fed in and the erected first blank In fig. 1 the strictly diagramatic illustration of the erecting unit 1 shows a shaping plate 2 which in this case has a rectangular opening 3. Below the shaping plate 2 there is a firmly fixed forming well 4 which can be fitted with an ancillary base 5, if required as well as support guides which have not been particularly illustrated. Above the shaping plate 2 there is a plunger 6 moving downwards in the direction of the arrow 7 through the opening 3 of the shaping plate 2 and through the forming well 4. On both sides of the forming well 4 are the heads of the ultrasonic appliance, the sonotrodes 8 and 9, producing ultrasound. These sonotrodes 8 and 9 move horizontally in the direction of the arrows marked 10 along the rods marked 11 which in turn are connected to the pneumatic cylinder 12 as shown in fig. 1. Here it is possible, as can be seen in fig. 2, to fit a swivel-mounted rocker arm (rocker disc) 14 between the rod 11 and * - 8 - <j0bi)63 O the pneumatic cylinder 12 which is mounted on a pivot 13 to which the rod 11 on the one hand and the piston rod 15 of the pneumatic cylinder 12 on the other are pivotally connected. The operation of this appliance according to the invention is as follows: First of all a blank 16 is put into position between the pulled up plunger 6 and the shaping plate 2 as seen in fig. 1. Those parts of the blank which are to be welded together by ultrasound have received an application of varnish of high solid content which has meanwhile hardened. After feeding in this blank 16, made of paperboard in this case, the plunger 6 moves down in the direction of the arrow 7 taking the blank 16 with it, so that the flaps 17 are bent upwards as they pass through the opening 3 in the shaping plate 2 thereby skirting the outer frame 18 of the plunger 6 as per fig. 2. For the sake of clarity forming well 4 and ancillary base 5 are left out in fig. 2. Once the procedure of erecting the flaps 17 of blank 16 is terminated, the pneumatic cylinders 12 allocated to the sonotrodes 8 and 9 go into action and push the sonotrodes 8 and 9 in the direction of the arrow 10 against the flaps 17 of the erected blank 16, the plunger 6 serving as counter support. As the sonotrodes 8 and 9 are positioned opposite one another, the pressure exerted by the pneumatic cylinders 12 is cancelled. To increase specifically the area pressure of the flat ends 19 of the sonotrodes 8 and 9, the outer frame 18 of the plunger 6 to which projection pins 20 pointing at the ends of the sonotrodes 8 and 9 respectively have been fitted, serves as an anvil as can be seen in fig. 4. The inside surfaces 21 of the blank 16 and the parts of the flaps 17 which are to be welded together lie flat against these projection pins. 'If these projections have a ribbed surface or projecting points; then <•* 9 - 205^6 these ribs or points penetrate into the parts of the blanks pressed against them, thereby reducing the distance between the plunger 6 and the sonotrode facing it which brings a corresponding increase of the effect of ultrasound. To achieve a a direct contact between the end flaps 19 of the sonotrodes 8 and 9 and the side flaps 17 of the blank, it is possible to cut out sectors of the forming well A through which the sonotrodes 8 and 9 can pass. Incidentally the forming well has been omitted from the diagrams fig. 2 to 5. As soon as the end flaps 19 of the sonotrodes 8 and 9 press against the side flaps 17 of the blank and thereby against the projections 20 on the sides of the plunger 6, the ultrasound turned out by the sonotrodes 8 and 9 heats up the synthetic material of the blank, alternatively the coating of synthetic material which has been applied to the blank, thereby welding the side flaps together. If the blank 16 is made of paperboard Vs and has a coating of varnish - as outlined earlier on - then this/likewise heated up by ultrasound and the adjacent flaps are welded together with this heated varnish of high viscosity. As per fig. 5 the sonotrodes 8 and 9 press against the blank flaps 17 for a sufficient length of time to weld the synthetic material and/or to harden the varnish between the blank flaps 17 thereby completing the welded joint. The folded carton 22 is thereby produced. Once this procedure is over, the sonotrodes 8 and 9 are retracted in the opposite direction of the arrows 10 returning to their starting point - as shown under fig. 1 and 2 - and the plunger 6 is pulled up in the opposite direction of the arrow 7. The support guides attached to the forming well k which are not specially illustrated, hold the finished carton 22 in position as shown in fig. 5. When the plunger 6 has reached 'ts original raised position, then a new blank 16 is fed on to the shaping - 10 - plate 2, thereby enabling a repetition of the procedure outlined above. Whilst moving down again, the plunger 6 erects the second blank 16 and thereby ejects the previously completed folding carton 22 downwards. • , * * / ' rV * i 17 SEP 1987 n-.tl L - 11 - Reference Table (Guide) t - /■. / . , r\ SsUoUbd 1 Erecting unit 2 Shaping plate 3 Opening in 2 4 Forming well 5 Ancillary base 6 Plunger 7 Arrow 8 Sonotrode 9 Sonotrode 10 Arrow 11 Guide rod 12 Pneumatic cylinder 13 Pivot 14 Rocker arm (rocker disc 15 Piston rod of 12 16 Blank 17 Blank flaps of 16 18 Outer frame of 6 19 End flaps of 8 and 9 20 Projections on 18 21 Inside surface of 17 22 Erected carton e«>'\ ft* °& UN ^ ^l7S£p|%7 </div>

Claims

<div class="application article clearfix printTableText" id="claims"> WHAT WE CLAIM IS - 12 - tiOootd 1. A method for forming a carton from a blank as claimed in claim 21 or 23 having sealing portions, said sealing portions having a coating resulting from applying substantially in the form of a varnish sufficient thermoplastic solids in a liquid vehicle to enable on heating and cooling a thermoplastic bond between any particular sealing portion and that other part of the blank with which a bond is to be formed, comprising forming the blank substantially to its carton configuration, moving a source of ultrasound to each zone of overlapping of a sealing portion with another portion of the blank with which a bond is to be made and effecting said thermoplastic bonding using ultrasonics from an ultrasonic sound producing sonotrode with a flat face to heat the thermoplastic solids when pressing the zone of overlapping against an anvil surface with a plurality of discontinuous projections thereon, increasing the pressure at the weld and allowing at least some cooling to enable the bond or bonds to be created prior to releasing the formed carton. 2. A method as claimed in claim 1 wherein the varnish applied to provide the coating comprises about 402 by weight acrylic resin and about 602 by weight liquid vehicle. 3. A method as claimed in claim 2 wherein said solvent comprises water with an inclusion of ammonia. / £0bub9 - 13 - A method as claimed in any one of the preceding claims wherein said > varnish applied is a high viscosity varnish measuring 60 to 70 seconds with a 40m/m DIN cup. A method as claimed in any one of the preceding claims wherein the ^ coating is applied to the sheet material blanks or the sheet material | ■r\ from which the blanks are to be die cut by offset printing. 'i A method as claimed in any one of the preceding claims wherein the quantity of the varnish applied to the blanks or the sheet material from which the blanks are to be die cut is 7 to 8g wet weight per M^. j| '-i # & A method as claimed in any one of the preceding claims wherein said j| blanks have been die cut to provide a base, side, ends and overlapping ■? flap elements, said method comprising: placing the blank over an open female forming die so made so as to define the corners of the carton base element, and in conjunction with a plunger to fold inward the sides, ends, and overlapping flap elements, pressing the blank into the said open forming die with said plunger having projections, bringing the flat face of a sonotrode against the outer of each pair of elements to be bonded with pressure sufficient to cause the projections of the plunger opposite to compress the said pair of elements in contact with each other, thereby reducing the distance between each sonotrode and the projections of the plunger at the welding interfaces of the pair of elements to be bonded. 17SEPI987 7 ' - 14 - xobobd energising the sonotrodes to heat the bonding medium to at least a tacky state, de-energising the sonotrodes while holding them under pressure against the outer surfaces of the formed carton until the bond has been effected, and withdrawing the sonotrodes to their initial positions. A method as claimed in any one of claims 1 to 6 when performed by positioning a sealing portion and another portion of the blank with which it is to be bonded between a sonotrode face and back up anvil, compressing the bonding area between said sonotrode face and back up anvil while delivering ultrasonic energy, holding the components in the compressed state after delivery of ultrasonic energy and thereafter separating the sonotrode and back up anvil to allow removal of the carton with that particular bond intact. A method as claimed in any one of the preceding claims wherein said varnish is applied to the blank using a pump. A method as claimed in claim 9 wherein said pump is a centrifugal pump feeding an offset printing machine to apply said varnish. A method as claimed in any one of the preceding claims when performed substantially as hereinbefore described with or without reference to any of the accompanying drawings. / 15_ 2U6;>t>9 12. An apparatus for welding the overlapping portions of folding or rigid cartons formed from flat blanks coated on at least one side of each pair of overlapping portions with a varnish containing thermoplastic solids, said apparatus having an anvil surface with a plurality of discontinuous projections thereon and an ultrasonic sound producing sonotrode with a flat face movable towards the anvil surface to clamp the said overlapping portions between the sonotrode and the anvil surface with sufficient force to compress the overlapping portions in contact with the said projections on the anvil surface, thereby reducing the distance between the sonotrode and the anvil at the welding interface of the two overlapping portions, increasing the pressure at the weld, and forming an adhesive bond at each weld. 13. An apparatus in accordance with claim 12 and further comprising said anvil being aligned with said ultrasonic sound producing sonotrode and acting in conjunction with a folding unit for folding a carton blank to be fed between said anvil and said sonotrode. 14. An apparatus in accordance with claim 12 or 13 and further comprising a second sonotrode opposed to said first-mentioned sonotrode and mounted for simultaneous relative movement toward and away from said anvil whereby said sonotrodes apply equal and opposite force simultaneously against said anvil. 15. Apparatus according to any one of claims 12 to 14 wherein the projections are either acute or end in blunt crests. % 1' I 1 I - 16 - &Obijc> 16. Apparatus as claimed in any one of claims 12 to 15 wherein said projections are a plurality of integrally formed ribs. 17. Apparatus according to any one of claims 15 to 16, characterised in that the apparatus comprises a plurality of displaceably mounted apparatus for generating ultrasonic waves (hereafter "ultrasonic means"). 18. Apparatus according to claim 17, characterised in that the ultrasonic means co-operate in pairs and are in each case disposed opposite each 19. Apparatus according to claim 17 or 18 characterised in that the ultrasonic means are pneumatically displaceable. 20. Apparatus according to claim 19, characterised in that a control disc is disposed between each ultrasonic device and the pneumatic device which produces its displacement. 21. A blank formable into a box on apparatus according to any one of claims 12 to 20 or by a method as claimed in any one of claims 1 to 11 characterised in that the blank is of cardboard coated at least at those locations which are to be bonded to one another with a hardened out dispersion lacquer which is capable of being rendered adhesive by the action of ultrasonic waves and the heating which is thus created. other. * - 17 - 206569 22. Apparatus as claimed in any one of claims 12 to 20 substantially as hereinbefore described with reference to any of the accompanying drawings. 23. A blank as claimed in claim 21 substantially as hereinbefore described. Uatto TMtsn,v DAY ISPS7 j PARK S SDN AGfcNTS FOR THE APPLICANTS Hsv-- </div>