Method and apparatus for the continuous production of package blanks

Abstract: The invention relates to a method and apparatus the continuous production of package blanks. The package blank is intended for delivering books by mail and it is fabricated by drawing from a roll a web of cardboard (1w), having a surface which is coated with adhesive zones (19) at distances corresponding to the length of a blank. A stud-chain conveyor (14) driven in synchronization with a cardboard-web (1w) chopping device supplies the adhesive zones (19) with paper strips (2p) forming an inner wrapper for the package.

Description: The present invention relates to a method for the continuous production of package blanks, wherein a web of cardboard is continuously drawn from a roll, the web of cardboard is guided through a pair of slotted cylinders for providing the web with a mild corrugation, lengthwise scoring lines are made at a small distance from both edges of the web, lengthwise adhesive strips are applied adjacent to the scoring lines, and the web edges are double-folded along the scoring lines. The invention relates also to an apparatus for the continuous production of package blanks, said apparatus comprising a roll housing for a web of cardboard, a pair of slotted cylinders for passing the web of cardboard therethrough in a mildly meandering fashion, a pair of cylinders fitted with scoring discs for producing lengthwise scoring lines adjacent to the edges of the web of cardboard, an adhesive station for applying an adhesive adjacent to the scoring lines, a folding shoe for bending the web edges along the scoring lines, a pair of press cylinders for pressing the doubled edges of the web of cardboard to the adhesive layer, a main drawing device included in the downstream end of the web of cardboard for continuously drawing the web of cardboard, and a cut-off device downstream of the main drawing device for chopping the web of cardboard to package blanks of a suitable length. A method and apparatus of the above type have been described in the Applicant's Patent publication EP 0,512,355. In that, the final package blank is completely made of the material of a web of cardboard. The use of material is not optimal since one side of a finished package will be provided with a triple cardboard (in places even quintuple) and the other side with just a single. US-A-4,627 223 proposes manufacturing of similar package blanks such that for manufacturing of each package blank both a cardboard sheet and a wrapper element are continuously driven on top of each other from supply rolls at a high rate. There is also proposed cutting of the webs to precise lengths between rotating cylinder cutters. There is no proposal to arrange delivering of pre-chopped inner wrapper elements onto a continuous web of cardboard. An object of the invention is to provide an improved method and apparatus capable of producing continuously and at a high production capacity from two different materials, namely cardboard and paper, a package blank which is optimal in terms of material consumption and suitable for packing books of varying sizes firmly and protectively. An additional object of the invention is to provide a method and apparatus enabling the use of a relatively thin, massive cardboard and its pre-crimping. The method of the invention is defined in claim 1. Further developments and modifications thereof are defined in claims 2 to 4. In view of landing the inner wrapper strips on proper spots at a high track speed, it is preferred that the supply and alignment of an inner wrapper strip and the alignment of an adhesive zone be controlled in synchronism with the action of a chopping device for the web of cardboard. Although the inner wrapper strips can be made in a separate production process and fed from a bundle onto the web of cardboard, it is preferred that the web of paper be drawn from a roll in a continuous action in the same preparation machine as the web of cardboard, the latter being drawn at a speed more than 2 times that of the web of paper. This eliminates a separate handling process required for inner wrapper bundles. The apparatus of the invention is defined in claim 5. Further developments and modifications thereof are defined in claims 6 to 8. In view of securing the feeding of inner wrapper strips to correct locations on the continuous web of cardboard, which travels at a high speed and will not be chopped until later, it is preferred that a transmission be provided from the cardboard-web chopping device to a stud-chain conveyor for delivering the inner wrapper strips in alignment with the adhesive zones. The invention will now be described in more detail with reference made to the accompanying drawings, in which fig. 1 shows a schematic side view of a machine for implementing the method; fig. 1A shows a larger-scale view of a detail in the machine of fig. 1, wherein a web of cardboard progresses through a pair of slotted crimping cylinders; fig. 2 shows a perspective view of an essential production method sequence for delivering the inner wrapper strips onto the web of cardboard; fig. 3 shows the web of cardboard in a cross-section along a line III-III in fig. 2; and fig. 4 shows a perspective view of a package blank fabricated with a method of the invention, comprising an outer cardboard 1p and an inner wrapper 2p. Fig. 4 illustrates a package blank fabricated by means of a method and apparatus of the invention and suitable for delivering books of varying sizes by mail. A rectangularly shaped outer cardboard 1p is provided with double-folded edge sections 23 having folding lines 21 which define the side edges of a package blank. In finished package, the edge reinforcements 23 protect and strengthen the end edges and corners of a package. The individual edge reinforcement 23 has a width which is 5-20 %, preferably about 8-15 %, of the width of a package blank. In the middle of the piece of cardboard 1p is secured with an adhesive a transversely directed inner wrapper, having free ends which are overlapped on top of each other in the middle of the blank. The inner wrapper 2p is provided with folding lines 22 which remain inside the folding lines 21. In view of making the blank adaptable to books of varying sizes, it is essential that the inner wrapper 2p be made of paper instead of rigid cardboard. This type of package is prior known from the Patent publication US 4,627,223. Since the package has proved highly versatile, an object of this invention is to provide a method and apparatus for producing such a package continuously and at a high production capacity. A roll housing 1 carries a roll of cardboard 1r for drawing a web of cardboard 1w therefrom. The cardboard consists of a compact solid pulp, having a thickness which is about 0,2-0,8 mm, preferably about 0,3-0,5 mm. The cardboard has a grammage which is about 200-600 g/m 2 , preferably 250-500 g/m 2 . If necessary, the web of cardboard is carried through a printing unit 3 for printing desired images and/or text on the cardboard surface. Next, the web of cardboard 1w is carried through slotted cylinders 4. As shown more accurately in fig. 1A, the cylinders 4 are provided with meshing grooves 26 and ridges 25 for creasing mild corrugations in the web of cardboard 1w. The gap between the cylinders 4 is adjusted such that the ridges 25 do not apply a strong compression to the cardboard against the bottoms of the grooves 25, whereby the cardboard becomes slightly corrugated but does not lose its normal rigidity. However, when the cardboard is folded around a book, the folding progresses along lines parallel to the corrugations and, thus, the package is given a neat appearance and the corners do not form sharp bends which are likely to cause tearing. Next, the web of cardboard 1w travels through scoring cylinders 5 which are provided with annular bosses for pressing the cardboard therebetween to form bending or creasing lines 21. Thus, the axial distance between the scoring rings defines the width of a package blank. An adhesive station 6 is used for applying lengthwise narrow adhesive strips adjacent to the bending lines 21, a folding shoe is used for double-folding an edge 23 and a pair of press cylinders 8 is used for securing the glue attachment of the edges 23. For example, a comb-lime adhesive nozzle 9 is used for periodically applying an adhesive onto the web of cardboard 1w to form adhesive zones 19, having a spacing which equals to the length of a package blank and web-directed length which does not exceed the corresponding length of the inner wrapper 2p. Prior to bringing the web 1w in between a pair of folding cylinders 15, the inner wrappers 2p are fed onto the web 1w in alignment with the adhesive zones 19. A pair of drawing cylinders 12 is used for continuously drawing a web of inner-wrapper forming paper 2w from a roll 2r, mounted on a roll housing 2. As shown by reference numeral 10, the paper-web edge sections are folded onto the middle web section for laying edge sections (24, fig. 4) on top of each other in an overlapping fashion. The folding is completed with cylinders 11 and the folded web of paper is chopped to the length of the inner wrapper 2p by means of a crosswise cutting cylinder 13. The chopped inner wrappers are carried forward by means of a stud-chain conveyor 14, whose speed and the distance between studs 14' determine a feeding interval for the inner wrappers 2p. The conveyor 14 is horizontal and the web of cardboard 1w arrives at the folding cylinders 15 obliquely from below. From the folding cylinders 15 a composite web continues in horizontal direction under the traction of main drawing cylinders 17. In order to provide a secure alignment of the inner wrappers 2p with the adhesive zones 19, the main drawing device 17, the cut-off device 18 and the stud-chain conveyor 14 for the web of cardboard 1w are provided with drives synchronized with each other so as to provide mechanically coupled transmissions therefor. Thus, no drift can occur even at high production rates. The main drawing cylinders 17 are pulling the web of cardboard 1w at a speed which is more than double compared to the paper-web 2w drawing speed effected by cylinders 12. This speed ratio determines the ratio of chopping lengths for a sheet of cardboard 1p and the inner wrapper 2p, which ratio is not highly critical since, by virtue of its flexibility, the paper-made inner wrapper 2p does not in any way limit the width of a package to be produced. Thus, the inner wrapper 2p can be wider or narrower than a package to be produced and still the outer cardboard 1p can always be wrapped tightly around a book or a bundle of books to be packed. In order to secure the landing of the adhesive zones 19 in the middle of only subsequently chopped cardboard sheets 1p, the periodic action of a valve 20 included in the adhesive nozzle 9 is synchronized with that of the cut-off'device 18 such that the cuts are always located in the middle of adhesive-free zones included between the adhesive zones 19 (dash-and-dot line in fig. 2). The sizing of inner wrapper strips 2p onto the web of cardboard 1w is secured by means of press cylinders 16 followed by the main drawing cylinder 17 and the cardboard-web cutting device 18, comprising a sufficiently large cylinder fitted with a transverse blade. The finished package blanks shown in fig. 4 are stacked and bundled for shipping. The package blank can be used for packing books of varying sizes by means of automatic machines such as described in the Patent publications EP 0,273,240, EP 0,378,783 and EP 634 321.

Claims: A method for the continuous production of package blanks, wherein a web of cardboard (1w) is continuously drawn from a roll (1r), guided through a pair of slotted cylinders (4) for providing the web with a mild corrugation, provided with lengthwise scoring lines (21) which are made at a small distance from both edges of the web (1w), lengthwise adhesive strips are applied adjacent to the scoring lines (21), and edges (23) of the web (1w) are double-folded along the scoring lines (21), the method comprising: periodically applying an adhesive aligned at distances corresponding to the length of the package blanks to a surface of the continuous web of cardboard (1w) to provide a series of adhesive zones (19); folding edge sections (24) of a web of paper (2w) on top of a mid-section of the web of paper such that the edge sections (24) overlap on top of each other; chopping the web of folded paper to form a series of separate inner wrapper strips (2p) for each associated one of a series of precision-length package blanks; delivering each of said series of separate inner wrapper strips onto said web of cardboard (1w) in alignment with each associated one of said series of adhesive zones (19) while the web of cardboard (1w) is continuously drawn towards a main drawing device (17); and chopping (18) the web of cardboard (1w) to produce said series of precision-length package blanks at locations between each one of the series of separate inner wrapper strips (2p). A method as set forth in claim 1, wherein the delivery and alignment of the series of separate inner wrapper strips (2p) with each associated one of said series of adhesive zones (19) are controlled synchronously with a cut-off device (18) for the web of cardboard (1w). A method as set forth in claim 2, wherein the web of paper (2w) is pulled from a roll (2r) continuously as the web of cardboard (1w) is drawn at a speed more than 2 times that of the web of paper. A method as set forth in claim 1, wherein the web of paper (2w) is pulled from a roll (2r) continuously as the web of cardboard (1w) is drawn at a speed more than 2 times that of the web of paper. An apparatus for the continuous production of package blanks, said apparatus comprising a roll housing (1) for a web of cardboard (1w), a pair of slot-ted cylinders (4) for passing the web of cardboard therethrough in a mildly meandering fashion, a pair of cylinders (5) fitted with scoring discs for producing lengthwise scoring lines (21) adjacent to edges of the web of cardboard, an adhesive station for applying an adhesive adjacent to the scoring lines, a folding shoe (7) for bending edges of the web (1w) along the scoring lines (21), a pair of press cylinders (8) for pressing doubled edges (23) of the web of cardboard to the applied adhesive, a main drawing device (17) at the downstream end of the web of cardboard for continuously drawing the web of cardboard, and a cut-off device (18) downstream of the main drawing device for chopping the web of cardboard (1w) to package blanks of a suitable length, the apparatus comprising: an adhesive nozzle (9) downstream of the pair of press cylinders (8) for the application of an adhesive onto the web of cardboard (1w) periodically so as to form a series of adhesive zones (19) at distances corresponding to the length of a package blank, and aligning and feeding means (14, 14') for delivering each respective one of a series of separate inner wrapper strips (2p) onto the web of cardboard (1w) in alignment with each associated one of said series of adhesive zones (19). An apparatus as set forth in claim 5, wherein a transmission (30) is provided from the cardboard-web (1w) chopping device (18) to a stud-chain conveyor (14, 14') for delivering each respective one of said series of separate inner wrapper strips (2p) in alignment with each associated one of said series of adhesive zones (19). An apparatus as set forth in claim 6, wherein the main drawing device (17), the cut-off device (18) and the stud-chain conveyor (14) for the web of cardboard (1w) are synchronized with each other so as to provide mechanically coupled transmissions therefore. An apparatus as set forth in claim 6, wherein the periodic action of a valve (20) included in the adhesive nozzle (9) is synchronized with that of the cut-off device (18) such that the cuts are located between each of said series of adhesive zones (19).

Inventors: JANHONEN VEIKKO, JANHONEN, VEIKKO
Applicants: PUSSIKESKUS OY
Application year: 1996
Main classification: B31B7
IPC codes: B31B17, B65D75, B31B7, B31B1, B31B39