The present invention concerns a procedure for grooving cardboard, corrugated pasteboard etc., in said procedure the cardboard being grooved and cut, inter¬ posed between two plate-like grooving tools, of which one, either one, constitutes a grooving blade and the other a counterpiece, and one of them, either one, con¬ stitutes a cutting blade and the other the cutting base. The invention further concerns grooving tools for grooving cardboard, said tools comprising a grooving blade and a corresponding counterpiece, and a cutting blade and corresponding cutting base, these being meant to be pressed against each other, the cardboard that is to be grooved and cut interposed between the tools.

Grooving is commonly employed in the box- making industry. The grooving is usually accomplished in connection with cutting the box blanks, that is in the punching or die-cutting step, in which the box blank is cut and grooved between punching tools in one single operation. Such punching can be done with the aid of punching tools which are pressed against each other, or using cylindrical punching tools, in this latter case the cardboard being fed through between roll-like punching tools rotating against each other. The punching and grooving procedure itself has been substantially unchanged for a number of decades. Devel¬ opment has in the first place been seen on the control and drive side of the machines, and in the area of tool manufacturing and setting up.

Grooving is at present accomplished by press¬ ing the cardboard between a grooving blade and a coun¬ terpiece, in the latter being provided a groove or fur¬ row opposite the grooving blade. The control variables in grooving are: breadth of the grooving blade and fur¬ row, and grooving depth. These variables determine the magnitude of the deformation caused in the cardboard

and the ultimate functional characteristics of the grooves.

Selection of the control variables in grooving is primarily made on the basis of the thickness of the cardboard that is being used, but other physical char¬ acteristics of the cardboard have their influence as well. As a rule, cardboard manufacturers give well- established values for the grooving settings to be used on their products. Owing to errors which occur in manu- facturing the grooving tools, the recommended values of the setting for grooving are not always implemented in practice. It can be estimated that deviations in the values of the settings on the order of 0.05 mm have an observable effect on the result of grooving, and devia- tions e.g. on the order of 0.1 mm may lead either to rupture of the cardboard in the grooving process or to problems in subsequent conversion steps.

In practice, problems are particularly caused by poor aligning accuracy of the grooving tools, i.e., of the grooving blade and its counterpiece, that is, the grooving blade fails to meet exactly the centre of the respective grooving furrow. The result is then a groove which bends one-sidedly and causes an error in the dimensions of the box, and may result in operating trouble in the side-gluing step or on the packaging machine. The error is usually due to the fact that al¬ though the grooving blade and grooving furrows are machined with high accuracy indeed, e.g. using laser cutters, numerically controlled machine tools, etc. , the blades and counterpieces are then attached to the respective work heads by hand, whereby the accuracy achieved in the machining step is often partly lost in the blade and counterpiece aligning step. In addition, when existing grooving procedures and tools are being used, the cardboard tends to become cut in particular when the grooving blade meets the grooving furrow asym¬ metrically.

In the Swiss Patent CH 533512, an attempt is made in connection with embossing and cutting to elimi¬ nate the drawbacks just related by using embossing rolls in conjunction with which the roll serving as embossing base has an outer surface layer made of re¬ silient material, e.g. of polyurethane. However, cutt¬ ing is accomplished in another work step, and the em¬ bodiment disclosed in the reference fails to solve the setting problems encountered in cutting and grooving. - It should be noted in particular that the embodiments disclosed in said reference do not concern themselves in any way with the problems arising from the centric positioning relative to each other of the cutting points and the embossing points, nor does the reference afford any solution thereto. Embossing and cutting done with the aid of rolls invariably causes problems in regard of the mutual alignment of the embossing points and the cutting points and of their well-centred place¬ ment. Through the reference US 4,586,431 a printing and embossing procedure of the same type is known as that of the Swiss Patent CH 533512, wherein the coun¬ ter-roll is provided with a surface layer made of elas¬ tic material. The above-mentioned problems inherent in the state of art are not brought forth in the refer¬ ence, nor does it present any solution thereto.

The object of the present invention is to eliminate the drawbacks mentioned in the foregoing. It is a specific object of the invention, to provide a novel grooving procedure, and grooving tools of a novel kind, and which do not present the problems, discussed in the foregoing, occurring in the alignment of groov¬ ing tools. Furthermore, it is an object of the inven¬ tion to provide a grooving procedure, and respective grooving tools, more favourable in operating and manu¬ facturing costs than before.

Regarding the features characterizing the in-

vention, reference is made to the claims.

The invention is based on the fundamental idea that the grooving is done against a counterpiece which is made of elastic material as of the partial region opposing the grooving blade. Thus, the counterpiece is substantially planar and resilient in the partial region facing the grooving blade, i.e., no particular grooving furrow need be provided therein. During the grooving process the resilient material will brace the cardboard that is being grooved, and the cardboard is partly pressed into said resilient material. No align¬ ment error will be incurred, whereby the grooves are invariably symmetric and they will therefore bend exactly at the intended point. Furthermore, thanks to the invention, and as the resilient material braces the cardboard while grooving is in progress, it is possible to cause greater deformations in the cardboard without causing its rupture; this enables the functional char¬ acteristics of the grooves to be influenced within wider limits than is possible at present. Furthermore, thanks to the invention, and as the resilient material braces the cardboard that is being grooved, elastically over the entire breadth of the grooving blade, the cardboard will be delaminated uniformly over the entire breadth of the blade, and without being cut.

As taught by the invention, grooving is imple¬ mented in connection with cutting, simultaneously to¬ gether with the cutting process. In this instance, i.e., in a die-pressing job, the grooving blade and cutting blade may be mounted on one tool and the coun¬ terpiece, respectively the cutting base, on another tool, i.e., on one opposed to the first. The cutting base is made, in the partial region facing the cutting blade, of mainly inelastic material, e.g. of metal. If desired, one may equally place the grooving blade and. the cutting blade on separate tools, in which case the counterpiece and the cutting base are correspondingly

mounted on separate, that is mutually opposed, tools. The latter embodiment allows the punching tools to be manufactured in a simpler way than before, and the dis¬ tending effect on the cardboard is substantially re- duced.

When the counterpiece and the cutting base are made, in their partial regions facing the grooving blade and, respectively, the cutting blade, of mainly non-resilient material, e.g. of metal or equivalent, and when the grooving blade and cutting blade are accommodated in one tool, the counter-tool, constitut¬ ing the counterpiece and the cutting base both, con¬ sists of different materials as of its partial regions facing the grooving blade or the cutting blade: of in- elastic material opposite the cutting blade, and of resilient material opposite the grooving blade. But no alignment problems whatsoever will arise, expressly owing to said partial regions and to their structure. When the cutting blade and the grooving blade are mounted on separate tools, the tool comprising the cutting base may consist substantially totally of a metal plate on which the grooving blade can be formed advantageously and inexpensively e.g. in the shape of a ridge-like eminence. The invention is described in the following in detail with the aid of embodiment examples, referring to the attached drawings, wherein:-

Fig. 1 presents in a schematic diagram an implementa¬ tion of the procedure of the invention, Fig. 2 presents the tools employed in the procedure of Fig. 1, and

Fig. 3 presents the tools employed in another embodi¬ ment of the invention.

Fig. 1 illustrates an implementation of the procedure of the invention. The cardboard sheet, or web, 1 is fed in between the tools 10 and 11 of a punch press 12. On one tool 10, in the embodiment here de-

picted the upper tool, which is called the mould, is fixed a grooving blade 2 and similarly a cutting blade 6 (these are visible in Fig. 2), and to the other tool 11, the lower one in the embodiment depicted, are simi- larly attached a counterpiece 3 and a cutting base 7 (both visible in Fig. 2). When the punching tools, the grooving blade 2 and the cutting blade 6 (i.e., the mould) and on the opposite side the counterpiece 3 and the cutting base 7 are pressed against each other, the cutting blade will cut from the cardboard, against the counterplate 7, a package blank of a shape as deter¬ mined by that of the blade. At the same time grooves are shaped in the blank by the grooving blade, against the counterpiece 3. Fig. 2 reveals the detailed construction of the tools 10 and 11. The tool 10 constitutes one tool of the punch, the mould, which is the upper tool in the present embodiment. The mould is composed of the fol¬ lowing components, attached to a plywood sheet 14, to a plastic sheet, to a metal sheet or equivalent: a groov¬ ing blade 2, a cutting blade 6, and ejector rubbers 15. The surface of the other tool 11, that is of the lower tool in this embodiment, comprises two kinds of re¬ gions: facing the grooving blades 2 is provided a coun- terpiece or counterplate 3, which is made of elastic material, while the cutting blades 6 are faced by a cutting base 7, consisting of a hard and substantially unyielding material, e.g. of a metal surface. In Fig. 2, the grooving blade 2 has just finished forming in the cardboard 1 a groove, and the cardboard has been partly pressed into the elastic counterpiece 2. At the same time, the cutting blade 6 has been driven against the cutting base 7 and it has cut the cardboard. In the grooving and cutting process the ejector rubbers are compressed, and recovery takes place in the detaching step. After the work step depicted in Fig. 2, the tools 10 and 11 are moved farther apart, whereby the ejector

rubbers detach the grooved and cut blank from the grooving blade and from the cutting blade. Tools 10 and 11 as shown in Fig. 2 constitute a punch according to one embodiment of the invention, which can be modified in various ways within the protective scope of the in¬ vention. For instance, the counter-plate 3 can be made, at the points facing the grooving blades, of any re¬ silient material whatsoever, e.g. of plastic, such as polyurethane, of rubber, etc. In Fig. 3 are presented punching tools con¬ forming to another embodiment of the invention, said tools comprising grooving tools and cutting tools. One tool 10, the upper tool in the present embodiment, or the mould, comprises counter-pieces 3 made of elastic material and fixed to plywood or equivalent fixing material 14 in positions consistent with the grooving lines, and cutting blades 6 fixed in positions consist¬ ent with the cutting lines. The mould moreover carries ejector rubbers 15. The opposed tool 11, that is the lower tool in this embodiment, is provided with a grooving blade 2 shaped on a metal plate 16 and con¬ sisting in this embodiment of a ridge-like eminence forming the grooving line. The grooving blade may be made e.g. of an iron wire fixed, such as welded, onto the metal plate. The metal plate 16 serves at the same time as cutting base 7 for the cutting blade 6. The grooving blade 2 may equally be formed in any other way whatsoever, e.g. of a ridge-like projection welded to the metal plate or otherwise formed thereon. In Fig. 3 the tools 10,11 have just been pressed together with the cardboard 1 interposed be¬ tween the tools. The grooving blade 2 has pressed the cardboard partly into the counterpiece 3, that is into the elastic material, thus forming a groove. At the same time the cutting blade has cut the cardboard, from the opposite side, i.e., the grooving blade and the cutting blade are mounted opposite each other on the

tools 11 and 10, respectively, similarly, the counter- piece 3 and cutting base 7 are disposed on mutually opposed tools 10 and 11, respectively.

In Figs 1, 2 and 3 in the first place the structural principle of the tools has been illustrated. The fixing of the grooving tools, that is of the punch¬ ing tools and/or cutting tools, to the work heads of the machine tool is implemented in any arbitrary way, e.g. as is known through earlier equivalent apparatus. Likewise the work step, i.e., grooving and/or cutting, i.e., pressing together the grooving and/or cutting tools, as well as introduction of the cardboard between the work heads and transport of the finished product towards further conversion or to packaging, is accom- pushed in any conventional way, and no more detailed description thereof is given in this context.

Operating the grooving procedure of the inven¬ tion, and the grooving tools, are simpler than those in existence. The grooving tools are easier to set up than before. The invention eliminates those chances of error which occur at present in the manufacturing of grooving tools, and it affords wider freedom than before to regulate and control the grooving event.

The embodiment examples are merely meant to illustrate the invention, and embodiments of the inven¬ tion may vary within the scope of the claims following below.