EP1358941A1 - Cutting tool for document shredder - Google Patents

Abstract

The documents (16) are fed into the nip between first and second cutting rollers (12b,13b). The cutting knives on the two rollers overlap, and the second roller is of greater diameter than the first roller. The rollers rotate at different speeds in opposite directions (n1b,n2b). Coarsely chopped pieces of paper (19) emerge from the first pair of rollers and are drawn into the nip of the third roller (14b). The third roller may be of the same diameter as the first roller and rotates (n3b) at a different speed in the opposite direction to the first pair of rollers. Finely chopped pieces of paper (18) emerge from between the second and third rollers.

Description

Field of application and state of the art

The invention relates to a cutter for a document shredder according to the preamble of claim 1 for reducing the size of objects or flat material, for example paper.

Such cutting tools usually have two cutting rollers with alternating interlocking cutting discs. The two Cutting rollers are driven in opposite directions and pull, for example paper to be shredded and cut it into strips. The The cut that takes place here corresponds approximately to one mechanically shear cut or a silhouette and takes place at the point instead, on which the adjacent cutting disks each other to grab. As such, the cutting performance achieved is satisfactory. However, there is a wide variety of other options to improve the cut of a document shredder and the Increase cutting performance.

Task and solution

The invention is based, an object mentioned To create cutter with which the cut and cutting performance of a document shredder can be improved, whereby the additional constructive effort should be limited.

According to the invention, this object is achieved by means of a cutting unit the features of claim 1. Advantageous and preferred embodiments the invention are the subject of further claims and are explained in more detail below. The wording of the claims will made by express reference to the content of the description.

According to the invention, the peripheral speeds of the cutting rollers are or cutting disks of different sizes. That way an exclusively shearing cut is not created as before, but a kind of "pulling cut". So this pulling cut is in For the purposes of this application, a combination or overlay from one purely shearing cut, such as with scissors which the cutting edges are only substantially perpendicular to the clippings move, and a knife cut with a cutting edge or move two cutting edges in the direction of extension of the clippings. With such a pulling cut, the severing can take place obliquely to the surface of the clippings are made as the resulting severing from a vertical section and a longitudinal section.

The cutting edges of the cutting discs run at a differential speed, which is calculated from the peripheral speeds, past each other. Through such a pulling cut or through such a partially pulling cut can be the cutting of paper or similar flat material can be facilitated. This way and Wise becomes by the provision of an at least partially pulling In this respect, the cutting performance with constant drive power increased than that cut more paper or thicker sheet material can be.

The peripheral speeds at the points or areas are preferred different sizes on which the cutting discs, in particular adjacent cutting disks, interlock. The difference between the peripheral speeds can range between 1% and 20% to 30%, preferably between 5% and 15%.

The cutting disks of one cutting roller are advantageous here similar in size with similar diameters. Show particularly advantageous they have the same diameter or are identical.

In one embodiment of the invention, it can be provided be that the cutting rollers have different diameters. The diameter difference can be between 1% and 20% to 30%, advantageous between 5% and 15%. Here it can be particularly beneficial be provided that the cutting rollers themselves have the same rotational frequency or have rotational speed. Because of the different Diameter becomes the different peripheral speed generates what is important according to the invention. For example the diameter of one cutting roller is 10% larger than that of the other Cutting roller, so is the same rotation speed resulting peripheral speed also 10% higher. In this invention Construction can be known per se a cutting unit Be used. The cutting rollers are for example such resize that a cutting roller has a larger diameter and the other cutting roller has a relatively smaller diameter receives. The drive facial expressions for the cutting rollers can be maintained stay.

In an alternative embodiment of the invention the cutting rollers have similar or the same diameter. This makes it possible, for example, advantageously, the cutting rollers to train identically or to build from identical cutting disks. This considerably simplifies the construction. At the same or almost The cutting diameters are the same for both cutting rollers the same. The cutting pressure is determined by the diameter of the Cutting rollers determined.

Here it is advantageously possible to use a different cutting roller To drive rotation speed. The difference in rotation speed can be between 1% and 20% to 30%, in particular are between 5% and 15%. With this second design option the cutting rollers will be at different speeds driven to achieve the pulling cut due to different Circumferential speed.

In a further embodiment of the invention, it is possible to have two or all Cutting rollers to be provided with separate drives. This means, that they each have separate drive motors.

Alternatively, a common drive motor for two or all Cutting rollers can be provided. By means of gears or gears can transfer the driving force to the cutting unit or the Cutting rollers are done. It is advantageously possible to achieve this different rotation speeds a gear reduction to be provided between the one and the other cutting roller, if so desired. The gear ratio is not the same here one and, for example, designed so that the aforementioned differences in the circumferential or rotational speed can be achieved.

In particular, it is possible to use a drive with a gearbox to connect the cutting rollers. This cutting roller in turn can via a further transmission with the second or with the corresponding one Cutting roller to be connected. This is advantageous here Cutting roller, which is directly connected to the drive via a gear is intended for the higher peripheral speed. This means, that the speed differences between the drive motor and slowest Cutting roller remain as small as possible.

It is advantageously possible within the scope of the invention to have at least one to provide additional cutting roller, making a kind of double cut possible is. This double cut ensures that flat material after passing through the first two cutting rollers, i.e. after the first cut, crushed again by a similar cut becomes. This makes, for example, a much better overall Shredding, especially in an irregular arrangement, possible.

Such a double cut in general form emerges from the EP 1285697 A, to which reference is hereby expressly made for Details of an arrangement.

According to one embodiment of the invention, the double cut or only a third cutting roller is provided for the second cut be that engages in one of the other two cutting rollers. This Engagement should be compared to the engagement of the first cut in the circumferential direction be offset. In this way it is only possible to achieve two cuts with three cutting rollers. So it will design effort kept low. In another configuration of the invention, which, however, is associated with a more constructive structure is, two pairs of cutting rollers are arranged one below the other.

It is advantageously possible for the second cut also a pulling Provide cut. This can be the case with the aforementioned first Design can be achieved in that the two cutting rollers, which effect the second cut, in the manner described above and Have different peripheral speeds. Here is it is possible to design all of the above of this pulling cut. It is particularly advantageous with a cutting unit with three cutting rollers for two pulling rollers Cuts provided that the cutting roller, which in both cases on Cut is involved, either by diameter or by rotational speed is different from the other two rollers.

Finally, it is advantageous if a cutting unit for one Double cut guide means are provided which are cut Flat material from the location of the first cut to the location of the second cut to lead. On the one hand, this should be such that the flat material after the first cut is removed from the cutting rollers. Furthermore can advantageously be provided that the flat material, as a rule in the form of parallel longitudinal stripes, swirl obliquely or mess it up so that on a second cut is cut irregularly. This is for data security reasons very advantageous. For this purpose, the guide means can, for example have comb-like wipers. It is also possible by blowing to achieve a swirl of compressed air or the like.

These and other features go beyond the claims from the description and the drawings, the individual Features each alone or in groups in the form of sub-combinations in one embodiment of the invention and in other fields be realized and advantageous as well as protective designs can represent, for which protection is claimed here. The Subdivide the application into sub-headings and individual Sections do not limit the statements made under these their generality.

Brief description of the drawings

Fig. 1

eine schematische Darstellung eines Schneidwerks mit zwei Schneidwalzen gleichen Durchmessers mit unterschiedlicher Rotationsgeschwindigkeit,

Fig. 2

eine Abwandlung von Fig. 1 mit drei Schneidwalzen zur Bildung eines Doppelschnitts, wobei die mittlere Schneidwalze einen größeren Durchmesser hat,

Fig. 3

eine schematische Darstellung eines Schneidwerks in Draufsicht mit zwei Schneidwalzen, die über Zahnräder mit einem einzigen Antriebsmotor verbunden sind,

Fig. 4

eine Abwandlung des Schneidwerks aus Fig. 3, wobei jede Schneidwalze einzeln über Zahnräder mit jeweils einem Antriebsmotor verbunden ist und

Fig. 5

eine Abwandlung von Fig. 1 mit zwei Schneidwalzen unterschiedlichen Durchmessers mit gleicher Rotationsgeschwindigkeit.

Embodiments of the invention are shown schematically in the drawings and are explained in more detail below. The drawings show:

Fig. 1

1 shows a schematic representation of a cutting unit with two cutting rollers of the same diameter with different rotational speeds,

Fig. 2

1 with three cutting rollers to form a double cut, the middle cutting roller having a larger diameter,

Fig. 3

1 shows a schematic illustration of a cutting mechanism in plan view with two cutting rollers which are connected via gears to a single drive motor,

Fig. 4

a modification of the cutting unit of Fig. 3, wherein each cutting roller is individually connected via gears to a drive motor and

Fig. 5

a modification of Fig. 1 with two cutting rollers of different diameters with the same rotational speed.

Detailed description of the exemplary embodiments

1 shows two cutting rollers, namely, a first cutting roller 12a and a second cutting roller 13a, quasi shown in section. You access in the usual way and Way with alternately arranged cutting disks one inside the other like usual cutting rollers of a document shredder. This is dashed shown. Their rotation is opposite. The first cutting roller 12a has the rotational frequency or rotational speed n1a and the second cutting roller 13a has the rotational speed n2a on. Instead of cutting rollers from individual cutting disks massive cutting rollers can also be provided. Here is the Disk shape by appropriate processing, for example turning, reached.

The cutting rollers 12a and 13a have alternately larger ones and smaller diameters. The smaller diameters are dashed shown. The cut takes place in the usual way between the larger diameters instead.

As can be seen, it is illustrated from above by the thick arrow 16, flat material introduced into the cutting mechanism 11a. After the cut falls below, represented by the thinner arrows 17, once cut Flat material out.

According to the invention, the two cutting rollers 12a and 13a same diameter here. However, the rotation speeds are n1a and n2a different sizes. Combined with the same diameter results from the cutting roller with the higher rotational speed n also the higher peripheral speed having. Mainly through this is the invention pulling cut causes.

In the cutter 11b in Fig. 2 there are three cutting rollers. This is the second cutting roller 13b. Left of it is engaged with the cutting roller 13b, the first cutting roller 12b is arranged. Below the second cutting roller 13b is the third cutting roller 14b arranged. As can be seen, the second cutting roller 13b acts both with the first cutting roller 12b together for a first Cut as well with the third cutting roller 14b for a second Cut.

The cuts can also be made through the symbolic representation of the flat material feed be recognized. Flat material 16 is again from above fed. After the first cut between the cutting rollers 12b and 13b becomes the once cut sheet 17 for the second Editing continued. The second cut takes place between the second Cutting roller 13b and the third cutting roller 14b instead. In the end kicks Flat material cut twice, represented by the very small ones Arrows 18, from the cutter 11b.

To redirect the flat material 17 once cut from the first Cut to the second cut, the wipers 19 are provided. This correspond approximately to the outer contour of the cutting rollers and engage in this one. They ensure that, on the one hand, the flat material is intended is performed, here from the first cut to the second Cut. Furthermore, the wipers 19 ensure that one Cutting roller does not fix cut flat material, which leads to a unfavorable blocking of the cutting unit could result. As before has been indicated, instead of the wipers 19, other differently functioning and / or differently designed guide means for the flat material may be provided after the first cut.

As can be clearly seen in FIG. 2, the second cutting roller has 13b has a significantly larger diameter than the first cutting roller 12b and the third cutting roller 14b. As a result, the rotational speeds n1b, n2b and n3b can be selected here. Due to the different diameters there is a pulling cut both between the first cutting roller 12b and the second Cutting roller 13b and between the second cutting roller and the third cutting roller 14b reached. Furthermore, what is not is imperative, the diameter of the first cutting roller 12b and third cutting roller 14b chosen the same. This mainly has the Reason that identical cutting rollers are used here can, which offers advantages in manufacturing. Even the one mentioned earlier Cutting pressure of the cutting rollers is the same.

However, with different cutting roller diameters is not imperative to choose the rotation speeds immediately. They can still be different. However, care must be taken that the rotation speeds are not chosen so that in connection with different diameters The end result is the same peripheral speed. Otherwise it would namely there is no pulling cut.

In Fig. 3 is a schematic plan view of a cutter 11c with a first cutting roller 12 and a second cutting roller shown. At the left end, the cutting rollers 12 and 13 are suspended in a bearing 20. On the right side, the first cutting roller 12 carries a first one Gear 22 and the second cutting roller 13 a second gear 23. The gears 22 and 23 mesh directly with each other, which also it is ensured that the cutting rollers rotate in opposite directions.

As can be seen, the pinion 24 engages the first gear 22 large drive motor 25. The cutting unit is thus driven 11c or the cutting rollers 12 and 13 via the pinion 24 of the Drive motor 25 to the first cutting roller 12. From this is about the gears 22 and 23 in turn driven the second cutting roller 13.

By choosing the diameter of the cutting rollers 12 and 13 or a gear ratio between the first gear 22 and the second gear 23, the respective peripheral speed the cutting rollers and their relationship to each other can be determined. Similar to the options described above, a pulling can Cut either through a different diameter of the Cutting rollers with the same rotation speed or different ones Rotation speeds achieved with the same diameters become.

It is also possible to modify the construction from FIG. 3 the connection between the two cutting rollers at the other end how to arrange the drive. However, this is due to design issues vote. It is also possible for the drive motor 25 to provide a gear connection directly to the second cutting roller 13. In the case of a cutting unit 11c according to FIG. 3, a third cutting roller would be present, this could either be via another gear are driven, this advantageously with the gear of Cutting roller is connected, with which the other cutting roller also cooperates. Alternatively, a direct drive via the drive motor respectively.

FIG. 4 shows a modification of the cutting mechanism 11c from FIG. 3. The cutting mechanism 11d in FIG. 4 also has two cutting rollers 12 and 13 which interlock. However, every cutting roller via a gear 22 or 23 and pinion 24 with small drive motors 26 connected. This enables the rotation speeds of the Cutting rollers 12 and 13 to be determined both individually and in operation to vary. A different rotation speed of the both cutting rollers can be unequal due to a gear ratio one between the gears 23 and 22 can be achieved.

The smaller drive motors 26 are intended to illustrate in comparison to FIG. 3 that, of course, with the provision of two drive motors 26 instead of a drive motor 25 this less power have to apply and can therefore be made smaller.

5 shows a cutting mechanism 11e. It consists of two Cutting rollers 12e and 13e. The cutting unit is similar in itself trained like that in Fig.1. However, here, similar to in the cutter 11b in Figure 2, the cutting rollers 12e and 13e different Diameter on. This is clearly recognizable. insofar the cutting rollers 12e and 13e roughly correspond to the cutting rollers 12b and 13b from Fig. 2.

The rotation speeds n1e and n2e should be chosen so that given the different diameters, the peripheral speeds are different. This is for example at an embodiment of the invention possible in that the rotational speeds n1e and n2e are the same. As previously stated the circumferential speeds are in the same ratio like the diameters to each other. Thus, the invention pulling cut achieved.

Claims (12)

Cutting device for a document shredder for shredding flat material (16, 17) with at least two roller-like cutting rollers (12, 13, 14) which have cutting disks, the cutting rollers being driven and the cutting disks rotating and interlocking, characterized in that the peripheral speeds of the cutting disks are different. Cutting device according to claim 1, characterized in that the peripheral speeds in the points or areas at which the cutting rollers (13, 13, 14) or cutting disks engage in one another are of different sizes, the difference between the peripheral speeds preferably being between 1% and 20% is, in particular 5% to 15%. Cutting device according to claim 1 or 2, characterized in that the cutting rollers (12, 13, 14) have different diameters, the difference preferably being between 1% and 20%, and in particular the cutting rollers (12, 13, 14) having the same rotational speed (n1, n2, n3). Cutting device according to claim 1 or 2, characterized in that the cutting rollers (12, 13, 14) have the same diameter. Cutting device according to one of the preceding claims, characterized in that the cutting rollers (12, 13, 14) have a different rotational speed (n), the difference in the rotational speed (n1, n2, n3) preferably being between 1% and 20%, especially 5% to 15%. Cutting mechanism according to one of the preceding claims, characterized in that two cutting rollers (12, 13) have separate drives with two drive motors (26). Cutting device according to one of claims 1 to 5, characterized in that at least two cutting rollers (12, 13, 14) have a common drive motor (25) and by means of gears (22, 23, 24) the drive force is transmitted to the cutting rollers, wherein a gear reduction between the one cutting roller (12) and the other cutting roller (13), which is not equal to one, is preferably provided to achieve different rotational speeds (n1, n2, n3). Cutting device according to claim 7, characterized in that a drive (25) is connected via gears (22, 24) to a cutting roller (12), preferably to the cutting roller with the higher peripheral speed, said cutting roller (12) via a further gear ( 22, 23) is connected to the other cutting roller (13). Cutting device according to one of the preceding claims, characterized in that at least one further cutting roller (14b) is provided for producing a double cut with a first cut and a second cut. Cutting device according to claim 9, characterized in that for the double cut, a third cutting roller (14b) engages in one of the two other cutting rollers (12b, 13b), preferably the third cutting roller (14b) and one of the two other cutting rollers (12b, 13b) have a different peripheral speed. Cutting mechanism according to claim 9 or 10, characterized in that the diameter of at least one cutting roller (12b, 13b, 14b) is different from that of the other cutting rollers, preferably from that cutting roller (13b) which is in the two other cutting rollers (12b, 14b) intervenes. Cutting device according to one of the preceding claims, characterized by guide means which, after the first cut, remove cut flat material (17) to a collecting device or to the third cutting roller (14b) and to the second cut, the guide means preferably carrying comb-like scrapers (19) have the entire width of the cutting rollers (12, 13, 14).

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