The invention relates to a blade and to a cutting device provided with such a blade.

Various machines, such as cutting presses and sheeters, are used in the paper processing industry.

In a cutting press pieces of paper and cardboard are punched to obtain a predetermined form and then for instance folded into a packaging such as a cardboard box. The residual material produced in such punching operations usually has irregular shapes, whereby this residual material will frequently catch on something during discharge thereof and result in malfunction. In practice such malfunctions usually occur several times an hour, and solving these malfunctions is labour- intensive and time-consuming. There is therefore a need to cut the residual material into small and manageable pieces so as to thus prevent malfunction.

NL2015719 describes a cutting device developed by Applicant which has been developed for the purpose of cutting through ribbon-like paper or cardboard strips, also referred to as off cuts, in an automated process. Such a ribbon is from several centimetres to about ten centimetres in width and can be up to 1500 metres in length, and is thereby very difficult to handle. Such a ribbon is on the one hand very thin and thereby has very flexible characteristics, whereby it is able to enter small gaps and can become stuck there. Paper which is compressed can on the other hand form a very rigid mass.

The device described in NL2015719 has been developed for the purpose of cutting off cuts for applications wherein the supply of residual material, i.e. the volume flow rate, is relatively limited and preferably reasonably constant. Situations also occur in practice however wherein the volume flow rate of the residual material is very variable, for instance varying from one sheet of paper to multiple layers of corrugated cardboard. The offcut can sometimes also have a width which approaches the width of the whole passage opening. An exceptionally high loading of the blade occurs in the case of stacked layers of cardboard and wide off cuts, resulting in considerable wear wherein a blade is blunt after about 60,000 cutting movements. Such a number of cutting movements can in practice already be reached in 24 hours. It is labour-intensive and undesirable to have to replace and sharpen the blade every 24 hours.

An object of the present invention is to provide a blade and a cutting device provided therewith wherein the stated drawbacks do not occur, or at least do so to lesser extent.

The stated object is achieved according to the invention with a blade comprising a carrier, at least one pair of long teeth which extend from the carrier, and wherein at least one short tooth is arranged between each pair of long teeth. The long teeth make first contact with an object to be cut, such as a paper or cardboard offcut, and subsequently penetrate the object, wherein perforations are formed at some distance from each other in the object to be cut. When the long teeth are subsequently pushed further into the object to be cut, the short tooth arranged between a pair of long teeth comes into contact with the object to be cut. The short tooth will here make contact with the object to be cut between the perforations already formed by the long teeth. The long teeth still extend here through these perforations, and thereby fix the object to be cut when the short tooth comes into contact with the object. When the blade is then pushed further, the short tooth will cut through the material of the object to be cut in the space between the two perforations already formed by the long teeth. The long teeth thus provide for a first penetration step, after which the one or more than one short tooth between the long teeth cuts through the remaining material in a cutting step.

Said object is further achieved according to the invention with a cutting device comprising:

- a wall with a passage opening configured for feeding therethrough an object to be cut; and

- a blade according to the invention movable along the passage opening substantially parallel to the wall.

Particularly advantageous preferred embodiments are the subject-matter of the dependent claims.

Preferred embodiments of the present invention are further elucidated in the following description with reference to the drawing, in which:

Figure 1 is a view of a cutting device according to the invention;

Figure 2 is a perspective view of a first preferred embodiment of a blade according to the invention;

Figure 3 is a top view of the blade shown in figure 2;

Figures 4-9 are top views of successive steps of cutting through an object with the blade of figures 2 and 3;

Figure 10 is a view of the object to be cut in the step shown in figure 4;

Figure 11 is a view of the object to be cut in the step shown in figure 7;

Figure 12 is a view of the object to be cut in the step shown in figure 8;

Figure 13 is a view of the object to be cut in the step shown in figure 9;

Figure 14 is a view of the object to be cut when cut through;

Figure 15 is a perspective view of a further preferred embodiment of a blade according to the invention; and

Figure 16 is a top view of the blade shown in figure 15.

The perspective view in figure 1 shows a cutting device 1 , comprising a wall 2 with a passage opening 3 configured for feeding therethrough an object to be cut 4, and a blade 5 movable along passage opening 3 substantially parallel to wall 2. The passage opening is at least partially clear during a stroke of movable blade 5 along passage opening 3, thereby preventing blockage of supplied objects to be cut 4. In order to prevent exposure of employees to blade 5 the wall 2 preferably forms part of a housing 6, wherein housing 6 accommodates movable blade 5 during the whole stroke thereof.

Cutting device 1 comprises an infeed 24 where objects to be cut 4 are inserted. Objects 4 to be cut are transported from infeed 24 to passage opening 3 by conveyors 25.

Provided close to passage opening 3 in the shown embodiment are counter-blades 23 along which movable blade 5 moves. Counter-blades 23 hold object to be cut 4 in place while teeth 8, 9 of blade 5 penetrate and cut through the object to be cut 4.

Figures 2 and 3 show a preferred embodiment of blade 5, comprising a carrier 7, at least one pair of long teeth 8 which extend from carrier 7, and wherein at least one short tooth 9 is arranged between each pair of long teeth 8.

In the shown preferred embodiment carrier 7 is elongate, wherein a plurality of pairs of long teeth 8 extend substantially transversely from carrier 7 and wherein at least one short tooth 9 is arranged between several of the plurality of pairs of long teeth 8.

Several advantages result from having an intermediate space 10 between a pair of long teeth 8 which decreases in size in the direction away from carrier 7. Long teeth 8 widen in the direction away from carrier 7, whereby intermediate space 10, i.e. the mutual distance, between two adjacent long teeth 8 close to an end 11 of long teeth 8 remote from carrier 7 has a minimum value. An advantage hereof is on the one hand that it results in a relatively wide penetration surface 12, and on the other that - precisely because of the widening of intermediate space 10 from end 11 of long teeth 8 in the direction of carrier 7 - space is created where material from the object to be cut 4 can displace in the direction of short teeth 9. Particularly in the case of a cardboard object to be cut 4 this widening of intermediate space 10 is highly advantageous because it prevents cardboard accumulating between long and short teeth 8, 9. Cardboard tends to form a very hard mass under pressure, removal of which is difficult and very labour-intensive. A further advantage of an intermediate space 10 enlarging from the end of long teeth 9 in the direction of carrier 7 is that space is formed between a pair of long teeth 8 for one or more than one short tooth 9.

Short teeth 9 can moreover have a width 14 at an end 13 thereof remote from carrier 7 which is at least equal to an intermediate space 10 between ends 11 remote from carrier 7 of the corresponding pair of long teeth 8 between which short tooth 9 is arranged. This results on the one hand in space for short tooth 9 and on the other allows end 13 of short tooth 9 to be sufficiently wide to cut through the material of object to be cut 4 between two perforations 15 arranged by a pair of long teeth 8 (figures 8 and 12).

When the one or more than one short tooth 9 widens in the direction away from carrier 7, the distance 16 between end 13 of short tooth 9 remote from carrier 7 and the adjacent long tooth 8 is reduced, whereby cutting though the material of object to be cut 4 between two perforations 15 arranged by a pair of long teeth 8 (figures 8 and 12) is further enhanced.

The top view of figure 3 shows that long teeth 8 are arranged obliquely relative to a longitudinal direction of carrier 7 and enclose an angle a of less than 90°, and that the one or more than one short tooth 9 is likewise arranged obliquely relative to the longitudinal direction of carrier 7 and encloses an angle β of less than 90°. Angle a and angle β are preferably substantially equal, whereby long teeth 8 and short teeth 9 extend substantially parallel in the direction away from carrier 7.

During operation at least long teeth 8 of blade 5 are aligned with the direction of movement of blade 5 running substantially parallel to wall 2 along passage opening 3, whereby the long teeth make contact one by one with the object to be cut 4. Short teeth 9 are preferably aligned in corresponding manner.

This arrangement ensures that teeth 8, 9 come into contact with object 4 one by one, whereby the force with which blade 5 presses on object 4 is concentrated in the respective tooth 8, 9 which at that moment comes into engagement with object 4.

The successive steps of cutting through an object 4 with blade 5 of figures 2 and 3 will now be further elucidated with reference to the top views shown in figures 4-9, wherein the advantage of an oblique position of teeth 8, 9 relative to carrier 7 will also become apparent. It is noted that counter-blade 23, which holds the object to be cut 4 in place, is not shown in figures 4-9.

In figure 4 a blade 5 approaches an object to be cut 4. Figure 5 shows the situation in which the long tooth 8 furthest to the left in the figure is already penetrating object 4 to some extent with its end 11 , and in which the following long tooth 8 is already lying against the surface of object 4. Because of an oblique arrangement relative to the longitudinal direction of carrier 7, teeth 8, 9 come into contact one by one with object 4 as they approach object 4 in substantially perpendicular manner. Carrier 7 is in that case oriented obliquely to some extent relative to the direction of movement of blade 5. Figure 10 is a view of the object to be cut 4 in the step shown in figure 4.

Figure 6 in turn shows a somewhat further step wherein the two long teeth 8 furthest to the left in the figure have already pierced object 4, the third long tooth 8 is penetrating object 4 and the fourth long tooth 8 is already lying against object 4.

In figure 7 a total of eleven teeth have penetrated object 4 and made a perforation 15 therein. Figure 11 is a corresponding view of object 4 in which perforations 15 are visible. In figure 7 object 4 almost comes into contact with the short tooth 9 furthest to the left in this figure.

Figure 8 shows that the short tooth 9 furthest to the left in the figure cuts through the material of object 4 located between two perforations 15 arranged in the object by a pair of long teeth 8. Figure 12 is a view of object to be cut 4 in the step shown in figure 8.

The perspective view of figure 2 shows that long teeth 8 decrease in thickness in the direction away from carrier 7. This creates an end 11 with a small height, whereby this end already penetrates object 4 at a lower force. The inclining long tooth 8 moreover forms a sliding surface for object 4. It is advantageous for the same reasons that the one or more than one short tooth 9 decreases in thickness in the direction away from carrier 7.

Provided close to carrier 7 between the one or more than one short tooth 9 and the adjacent long teeth 8 is a sliding surface 17 which decreases in thickness in the direction away from carrier 7 (figure 9). This sliding surface 17 forms a guide for the cut residual material of object 4. Figure 13 is a view of the object to be cut 4 in the step shown in figure 9, and figure 14 shows the object 4 when cut through.

In the embodiment shown in figures 2-9 one or more than one long tooth 8 is provided at an end 11 remote from carrier 7 with a V-shape 18 which forms two penetration points 19. This V- shape 18 has the advantage that the material of object 4 is first engaged at the locations of perforation 15 by the two penetration points 19 and is guided by V-shape 18 in the direction of the centre of tooth 8 via an oblique surface 20. As a consequence the material of object 4 is guided away from intermediate space 10 between long teeth 8.

According to a further and alternative preferred embodiment, one or more than one long tooth 8 is provided at an end 11 remote from carrier 7 with an reverse V-shape 21 which forms one penetration point 22. This alternative preferred embodiment is shown in figures 15 and 16, and is otherwise identical to the embodiment shown in figures 2-9.

Although they show preferred embodiments of the invention, the above described embodiments are intended solely to illustrate the present invention and not to limit the scope of the invention in any way.

It is noted that for the purpose of the example the object to be cut 4 is represented as a relatively thin and single strip. Teeth 8, 9 of the blade are however suitable to cut through several layers of cardboard, in which case the shown object 4 can be seen as the outer layer.

When measures in the claims are followed by reference numerals, such reference numerals serve only to contribute toward understanding of the claims, but are in no way limitative of the scope of protection. It is particularly noted that the skilled person can combine technical measures of the different embodiments. The described rights are defined by the following claims, within the scope of which many modifications can be envisaged.