METHOD FOR MANUFACTURING LOAD-CARRYING ELEMENTS |
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申请号 | EP05730931.2 | 申请日 | 2005-04-06 | 公开(公告)号 | EP1737739B1 | 公开(公告)日 | 2009-09-02 |
申请人 | SUOMEN KUITULAVA OY; | 发明人 | RANTANEN, Kari; | ||||
摘要 | The invention relates to a method for manufacturing load-carrying beam-like elements (4) and to the manufacture of a loading base, such as a pallet, by using the elements thus obtained. The elements (4) consist of tubular paperboard cores (1) and covering paperboard (2) surrounding them, and for forming the elements, cores are aligned on a paperboard sheet or web, which is provided with weakening lines (9) transverse to the direction of the row of cores, the weakening lines allowing, in accordance with the invention, a beam (3) assembled from paperboard and cores to be divided into shorter parts, i.e. to be provided as beam-like elements, by cutting the beam (3) along each weakening line. The weakening lines (9) consist e.g. of perforations (9) made in the paperboard (2), and then the elements (4) are separated from the beam (3) by an impact directed to the elements. The elements (4) can be assembled e.g. with a connecting covering plate to form a pallet, where the load is exerted on the elements in the axial direction of the cores (1). | ||||||
权利要求 | |||||||
说明书全文 | The invention relates to a method for manufacturing load-carrying elements, in which tubular paperboard cores are disposed in a row and are assembled by means of a covering paperboard to form a beam aligned with the row of cores. The invention also relates to the manufacture of a loading base such as a pallet comprising the supporting elements thus obtained. Paperboard cores manufactured by gluing helically wound board layers on top of each other to form a tube with a multi-layered mantle have been conventionally used as cores in paper rolls, on which the load is exerted laterally. Pallets utilising the high axial compression strength of the cores form a second object of application of paperboard cores. The cores and the covering paperboard are assembled into beams, which are aligned and joined by means of a covering plate to form a pallet, in which the core axes included in the beams are perpendicular to the plane of the pallet. The pallet may also comprise beams crosswise in two layers, and then no covering plate will be necessary in order to assemble the pallet. Such prior art disposable pallets made of recyclable material have been disclosed by In It is also previously known in the manufacture of pallets to produce beams consisting of cores and covering paperboard in serial production, by disposing the cores on a continuous moving board web, which is wrapped around the cores and glued to them, forming a continuous beam which is eventually divided into sections of the desired lengths by means of a cutter of by sawing. However, the cutting of a prior art beam that is previously assembled and glued involves a number of drawbacks. If adjacent cores bear on each other in the beam, a cutter performing a reciprocating linear movement has problems in hitting exactly between the cores with a precision such that the beam can be cut. The same applies to rectilinear sawing of the beam, which should be carried out without damaging cores in the vicinity of the cutting point. In the practice, cutting of the beam requires a gap to be left between the cores located on both sides of the cutting point. On the other hand, cutting the beam by means of a tool sawing or slitting the covering board and rotating around the beam at the cutting location is a more laborious operation. The cutting mark produced by the saw is often rough, and it is difficult to combine the two cutting manners, i.e. a linearly proceeding movement and a movement rotating around the beam, in a manufacturing process based on a continuous movement of the beam. The purpose of the invention is thus to improve the process for manufacturing beams formed of paperboard cores and covering paperboard, comprising the cutting of a previously assembled beam into sections of specific lengths. The invention has the specific purpose of providing a solution by means of which a beam can be cut with less effort than before while producing a neat cutting mark. The method of the invention is characterised by the fact that, before the beam is assembled, the covering board is equipped with one or more weakening lines transverse to the direction of the row of cores and in that each element formed of paperboard and cores is separated by cutting the beam along the weakening line. In accordance with the invention, the covering paperboard may have been weakened in advance to an extent such that no cutting tool is needed for detaching the element to be separated, i.e. the beam of a specific length forming the end product of the method, the beam being removed by a simple impact. The invention does not require the cutting location to be between the cores with the same absolute precision as does cutting of the beam by means of a linear cutter movement or by sawing, and hence the cores may be located closer to each other at the cutting location and even in contact with each other without preventing cutting of the beam. The weakening lines required by the invention are preferably perforations of the covering paperboard. The weakening line may consist of dot-like or preferably linear perforations penetrating through the paperboard and covering the weakening line so that the portions on the two sides of the line are weakly joined only by narrow bridges between the perforations. The bridges are required to have only a strength such that the paperboard can be wrapped around the cores without breaking prematurely. Previously made long linear perforations and a minimum number of bridges also achieve the most even cutting mark. Light slitting of the board surface at the bridge locations also contributes to this. A weakening line can be produced in a paperboard sheet or web e.g. by means of a reciprocating tool of saw blade type, which produces linear perforations in the paperboard that separate the bridges from each other. Assuming that a light impact is enough for final cutting of the beam, cutting the beam by means of said tool in accordance with the invention is a substantially easier and more secure operation than dividing an intact beam as in the prior art operation. Perforations or any similar weakening lines can be produced in the paperboard sheet or web while it is in a single plane, i.e. before starting to bend the web around the cores. It is also preferable to produce the weakening lines in the sheet or web before placing the cores on this. This allows the cores to be disposed in mutual contact also at the location of the weakening line. The invention is particularly suitable for continuous manufacture of elements, i.e. beams of a specific length, which is performed by forming transverse weakening lines in a continuous paperboard web at intervals equalling the lengths of the elements, aligning cores on the web, wrapping the web around the row of cores to form a beam and dividing the beam along the weakening lines to form separate elements. The invention can optionally be implemented by producing a beam of a specific length comprising one or more transverse weakening lines, the beam being divided into parts by supporting the beam between the weakening lines and directing a blow or an impact simultaneously to both ends of the beam for detaching the part to be separated. The method of the invention for producing a loading base, such as a pallet, comprises the manufacture as described above of elements consisting of paperboard cores and covering paperboard, i.e. beams of specific lengths, which are disposed next to each other and bound to each other to form a base, with the base receiving the load exerted on it in the axial direction of the cores. The beams can be connected to form a pallet by means of a covering plate, on which the load carried by the pallet is placed. Beams are preferably aligned on the pallet in succession and separated from each other, allowing a lifting fork to grip the rectangular pallet from all four sides of the pallet by penetrating between the beams. The invention will be explained in further detail below by means of examples and with reference to the accompanying drawings, in which
The production line of In a closer study of the process of In the embodiment of the invention illustrated in The cores are disposed on the web 2 by means of the vertically reciprocating tool 13 gripping the cores with its fork 12 as illustrated in After the cores 1 have been disposed on the web, the web 2 is bent around the row of cores by means of guides (not illustrated). This results in a beam 3 with a rectangular cross-section, in which the crease lines 5 of the web form the edges of the beam, the central strip 6 of the web forms the bottom of the beam, the inner border strips 7 form the vertical sides of the beam and the outer border strips 8 form together the upper side of the beam. The aligned border strips 8 form a longitudinal seam line 14 on the upper side of the beam. To bind the beam 3, glue is applied to the web 2 and/or the cores 1 before the web is bent. The continuous beam 3 provided with transverse weakening lines 9 obtained in the last process step is divided into parts by cutting the beam along each weakening line. This results in beam-like elements 4 of specific lengths, each of which has two adjacent paperboard cores 1 surrounded by the covering paperboard 2. The cutting tool consists of a hydraulically reciprocating hammer 15, which separates an element 4 by a light impact on this. The production of the beam 3 can differ from the procedure described above by forming the weakening lines 9 before the web 2 is provided with longitudinally scored crease lines 5. The paperboard web 5 is preferably formed of a plurality of material webs on top of each other, and then the weakening lines 9 can be formed separately in each of these before the webs are joined together, so that their weakening lines coincide. The material webs are bound together by means of glue, and the crease lines 5 are preferably scored to the layered structure of the web 2 before the glue dries, i.e. while the web is moistened or softened by fresh glue. A covering paperboard 2 glued in multiple layers imparts the beam 3 rigidity, which facilitates the division of the beam into elements 4 and produces stronger elements for various loading applications. In The application of the pallet 21 shown in It is obvious to those skilled in the art that the applications of the invention are not restricted to the example given above, but may vary within the scope of the accompanying claims. Thus, for instance, instead of one single continuous web or sheet, the covering paperboard of the beams may consist of two separate webs or sheets, one of which surrounds the cores 1 on their bottom side and the other one surrounds them on their top side, so that the webs or sheets form together the longitudinal sides of the elements. The cores are not necessarily surrounded by covering paperboard on all the longitudinal sides, but the beam and accordingly the elements separated from this can be left partly open, provided that the gluing is adequate for assembling the elements. |