METHOD OF AND APPARATUS FOR THE AGGLUTINATION OF SHEETS

Abstract: A method for the agglutination of a plurality of sheets (2), more particularly of paper, arranged in a stack. A punching mechanism (1) provided with a channel through which melted or dissolved adhesive can be dispensed is passed through the stack to cut a throughgoing hole (9). Said hole is formed by U-shaped, serrated or corrugated slits presenting in each sheet one or more tongues (10) which the downward movement of the punching mechanism causes to bend away from their original positions while at the same time adhesive is introduced into the hole. The retraction of the punching mechanism causes the tongues to unbend and return to their original positions, which has the effect of introducing the adhesive between the individual sheets and accomplishing the agglutination. The invention further relates to an apparatus for the embodiment of the method according to the invention. The apparatus comprises a support (3) for holding a stack of sheets (2) and a cutting mechanism (1) with an end face (13) of an angular or corrugated cross section. Said cutting mechanism is provided with a hollow shaft (6) and means (14, 15, 17, 18, 19) for depositing adhesive on the punched-out tongues. Furthermore, the apparatus is provided with means (12, 16) for returning after the application of adhesive to the tongues and retraction of he punching mechanism the bent-down tongues to their original positions.

Description: Method of and Apparatus for the Agglutination of Sheets The invention relates to a method for the agglutination of sheets, more particularly of paper, but also of materials such as card¬ board, textiles, foils, or the like, irrespective of vhether the said sheets are of the same material or of different materials, and a-n apparatus for the embodiment of the method. A videly used means for in erconnecting a number of sheets of pa¬ per or other materials, especially where the sheets have to be folded after the interconnection, as for example in the case of catalogues and magazines, is metal staples. Other methods invol sewing or welding. However, agglutination is also used, for exa pie in newspaper production where strips of glue the entire length of the newspaper are used for joining the individual pa ¬ ges. But agglutination of sheets of paper, especially of a plur lity of sheets, seems to be industrially advantageous in partic* lar where it is possible to apply a flexible adhesive to a free edge of a stack of paper sheets. This is the method used for ex ample in the production of writing pads. But the agglutination accomplished by this method has only limited strength as the individual sheets of the stack partake only of a very narrow strip of glue. According to British Patent No 1,305 . *+8 a number of paper shee may be interconnected in the vicinity of the edge of the stack punching holes in the stack and in the same operation introduci: an adhesive into the hole, from which the adhesive is then sup¬ posed to spread between the individual sheets. A very similar π* thod for interconnecting the sheets of a stack of paper by punc ing a hole for the introduction of glue is known from Vest Ger¬ man OS No 2 ' 055 127. The agglutination of superposed sheets can be improved by fa-nni: the sheets before subjecting them to adhesive. This method is known from the specification of British Patent No 681,858. French Patent No 1,016,027 states a method for agglutinating sheets of paper by which fairly long tabs in the shape of narro tongues are punched up out of a line in the sheets and then ben back completely and subjected to adhesive whereafter said tongu are unbent again and made to combine into an interlace which if? secured to the outermost surface of the stack. This agglutinati of interlaced tongues serves to interconnect outside the actual stack of sheets not only the individual sheets of the stack but also the stack and similar consecutively arranged stacks of fol ed paper, for example for bookbinding purposes. The problem underlying the present invention is to provide a m β thod which permits, better than any hitherto known me * ϋ«_rt ^-rτca pid, economical and tear-resistant agglutination, especially in the case of sheets that have to be folded after the interconnect¬ ion. There seems to be no method in existence by which for ex¬ ample far larger numbers of sheets may be joined in one opera¬ tion than is possible by means of the commonly used staples, and which implies less risk of tearing out of individual sheets than by methods involving the use of staples. The specific character of the present invention is described in the characterising part of Claim 1. In one embodiment of the invention it is proposed to provide a means for applying a thin strip of cardboard or the like to the strip of adhesive on the uppermost sheet immediately after adhes¬ ive has been applied and the tongues bent back. This permits the agglutinate stack of paper sheets to be transferred, folded or in any other manner further processed, even before the adhesive de¬ posited on the sheets is dust dry, still less thoroughly hardened, The method according to the invention provides strong and tear- proof agglutinations. Furthermore, it can be automated and is economical in terms of consumption of time and adhesive. The pre¬ sent invention makes it possible to agglutinate even very large numbers of sheets in one operation, since the punched-out tongues can be very short and yet permit an effective agglutination. The fact that the final hardening or setting of the adhesive takes place inside the stack with the tongues returned to their origin¬ al positions and with adhesive deposited between the slits of all the sheets provides a strong reinforcement of the hole where the agglutination takes place, preventing that any of the sheets become detached or can be torn put very easily. Thus agglutina¬ tion of sheets of a wide variety of materials becomes a new alter native to methods of interconnection by means of staples, sewing, welding, etc. , and opens up the possibility of new industrial ap¬ plications for example agglutination of textiles. In the following the invention will be more specifically descri¬ bed with reference to the accompanying drawing in which figure 1 is a perspective view of one embodiment of an _8,_Ej * r- * . * tus according to the invention figure 2 shows examples of the shapeε of the punched-out slits figure 3 is a longitudinal section through a combined punching and adhes ve-applying mechanism figure shows another embodiment of the adhesive-applying me¬ chanism figure 5 shows yet another proposed embodiment of same Figure .1 shows the lower part of two suitably interconnected co: bined punching and adhesive-applying mechanisms in a position where they have been moved vertically down towards and now just touch a horizontally positioned stack of paper sheets 2 resting on a support 3- Other directions of movement and other angles between the surface of the stack and the direction in which the punch is introduced are also possible, but an angle of approxi¬ mately 0 seems preferable. The dot-and-dash line h on the she of paper suggests a line along which the stack of sheets may be folded after the agglutination. The agglutination can also adva: tageously be performed along an outer edge of * the sheets. By means of a suitably flexible and movable tube 7 "the shaft 6 of the punching and adhesive-applying mechanism is connected to a container 8 for adhesive, which can advantageously be temperatu and pressure controlled to ensure convenient and even feed of a' hesive. The solid lines in figure 2 show a number of many possible shap of the slits 9 punched out in the sheets, whereas the dot-and- dash lines show how the tongues 10 presented by the punch are bent down by the punching and adhesive-applying mechanism. The hatched areas represent the hole produced in the sheets by the punching operation. It is apparent that by choosing for example a serrated or corrugated slit it is possible to adjust the leng of the strips of adhesive so that even in a limited area fairly long strips can be obtained and thus adapted to the type of she to be agglutinated. The punched-out tongues 10 need only be of very as will be apparent from figure 3. since the width of the strip of adhesive 11 deposited on the underlying sheets is determined by the degree of displacement of the bent-down tongues. Beyond a very narrow limit depending on such factors as the thickness of the sheets and on the angle of bending increasing the length of the tongues does not increase the displacement. Furthermore, ΓΘ - la-fcively short tongues are advantageous in that they are capable of being more rapidly and conveniently returned to their original positions after the adhesive has been applied to them. Returning of the tongues can for example be effected by means of the two spring-loaded plates 12 situated in the support 3- However, the individual tongues need not be returned to their exact original positions. A certain degree of overlapping might even be advan¬ tageous. Such overlapping can be aided by letting the tongues be of a suitable shape, for example S-shaped, cf the last example shown in figure 2. By the method according to the present inven¬ tion an effective agglutination of a fairly high stack of paper sheets can be accomplished without the tongues having to be long enough to be secured outside the stack. On the contrary, if the tongues are too long there is a risk that they may become entan¬ gled and thus form an obstruction preventing the complete passage of the adhesive-applying mechanism through the stack. In the simple embodiment of the combined punching and adhesive- applying mechanism shown in figure reference number 13 designa¬ tes the punching tool, which is attached to a suitably hollow shafi 6 provided with channels 14 through which melted, dissolved or dispersed adhesive can be fed evenly to a pad 15. The pad 15 can be made of felt, foam rubber or any other porous material and can have a cross section corresponding to the hatched areas in figure 2 which represent the holes formed in the stack of paper sheets and to whose sides the adhesive is applied. Returning of the bent-down tongues 10 to their original positions can for example be effected by means of two underlying spring- loaded . plates 12, the contiguous edges of which can advantageous¬ ly be adapted to the shape of the slit and thus to that of the tongues. As the punching and adhesive-applying mechanism passes through the stack the spring-loaded plates 12 are pressed down to positions which form an angle approaching 0 with their ori g±nal positions. In the retraction of the combined mechanism, • which follows immediately on the punching operation the springs l6 cause the spring-loaded ' plates 12 to return to their origin; position at the same time forcing the entire column of tongues i* wards to take up positions in the vicinity of their original po sitions in the stack where the final setting or hardening of th > adhesive takes place. The fact that by the displacement of the tongues relative to each other adhesive has been distributed ovi "the surface of each individual tongue ensures that when the ton gu.es are returned the adhesive will spread well when it is pres¬ sed out between all the sheets of the stack. If desired, the pressure on the sheets can be increased by letting the spring- loaded plates 12, which can advantageously be provided with a coating of an adhesive-repellent substance for example teflon bι controlled, instead of by the springs 16, by a special clamping mechanism, which advantageously can be coordinated with- the mech. nism for applying to the tacky areas on the uppermost sheet soπ-i means for inhibiting the adhesive effect, for example at least one piece of thin cardboard or plastics film, a powder or the like. Figure shows another possible embodiment of the adhesive-appl ing mechanism, in which the porous pad 1 is replaced by a kind of brush. Approximately at right angles to the direction of ope¬ ration are mounted a number of fairly stiff hairs or the like 1' The upper part of figure 4 shows an alternative to the brush, i_ the form of short, small-bore tubes 18 allowing the passage of adhesive. This form of the invention may provide an even better spread of the adhesive between the individual sheets of the sta< and furthermore the subsequent retraction of the adhesive- apply¬ ing mechanism will aid the returning of the bent-down tongues. As shown in figure 5 t .e introduction of adhesive can also be accomplished by means of a solid stick of adhesive 19, which cai for example be slightly tapered at one end to ensure a gradual ^ newal. This form of the invention might be particularly ad anta- geous for a smaller and simpler embodiment of an apparatus accor¬ ding to the invention, which could replace for example small sta ¬ plers for metal staples. The abovementioned adhesive inhibitor of cardboard may be needed in particular for the uppermost sheet, which is the first to be touched by the adhesive-applying mechanism, adhesive being appli© 1 to the entire area indicated in figure 2 by hatching. A similar passivation may be required for the adhesive applied to the ne¬ thermost sheet of the stack, for example in the form of a powder such as talc, which can prevent any undeεired adhesion to other surfaces. Alternatively, a kind of simple passivation can be ob¬ tained by folding the sheets immediately after the agglutination for example along the dot-and-dash line 4 in figure 1. A further advantage gained by passivating at once any inappropriately adhes¬ ive surfaces is that it permits the use of more slow-drying ad- hesiveε, with for example water as disεolving or dispersing agent and thus less harmful to the working environment.

Claims: CLAIMS 1. Method for the agglutination of sheets of paper, cardboard, textiles, foils, leather or other materials wherein a punch ¬ ing mechanism is passed through the sheets to be aggluti¬ nated to punch out at least one slit, and thus a tongue or tongues, of serrated, corrugated or any other suitable cross section permitting that in the passage of an adhesive-ap¬ plying mechanism, preferably associated with the punching mechanism, a suitable hole is established through the sheets, while at the- same time adhesive is applied to the tongues which are bent and fanned in the formation of the hole, whereafter said tongues, are returned to substantially their original positions in or after the retraction of the punch¬ ing and adhesive-applying mechanism so that the final agglu¬ tination is effected inside the stack of sheets. 2. Method "as claimed in claim 1, wherein directly in connection with the application of adhesive at least one strip of thin cardboard or plastics foil, a powder or any other adhesive- inhibiting means is applied to the adhesive areas of the upp. surface of the uppermost sheet or sheets of the agglutinate stack. 3_ Apparatus for carrying out the method claimed in claim 1, wherein are provided a support for supporting a stack of sheets and further a punching mechanism for being passed through the stack of sheets in the direction of the support and which includes a leaf-shaped cutting tool with an end fat for example of angular or corrugated cross section and a sha. on the surface of which are provided means for applying adhe. ive to the tongues punched out of the sheets by the cutting tool, and further a means for returning as the cutting tool is retracted the bent-down tongues to substantially their or: ginal, mutually parallel positions. 4. Apparatus as claimed in claim 3 . wherein the support is pro¬ vided with at least one movable plate suitably adapted to the cross sectional shape of the cutting' tool end face and capable of yielding when acted on by said end face as it passes throug] the stack and further capable of springing back at the same time causing the punched-out and bent-down tongues to return to substantially their mutually parallel positions. 5. Apparatus as claimed in claim 3. wherein the dissolved, melted or dispersed adhesive is fed from a container which can advan¬ tageously be pressure and temperature regulated to pass throug] movable tubes into the hollow shaft of the punching mechanism from where it passes on through channels in the shaft to be deposited on the porous pad or the brush or the equivalent thereof of the adhesive-applying mechanism or the adhesive can pass out through fine tubes connected with the channels of the shaft and arranged preferably at right angles to the direction of travel of the shaft. 6. Apparatus as claimed in claim 3, herein the adhesive is ap¬ plied by means of a solid stick of adhesive which advantageous¬ ly can be associated directly with the punching mechanism. 7. Apparatus as claimed in claim 3 . wherein is provided a means for carrying out the method as claimed in claim 2.

Inventors: GRAM O
Applicants: GRAM O, GRAM O AS
Application year: 1979
Main classification: B42C9
IPC codes: B42B5, B42C9