DE29622352U1 - Knife with sawtooth profile - Google Patents

Description

The invention relates to a knife with a sawtooth profile, consisting of a plurality of triangular individual knives arranged at a lateral distance from one another on the front edge of the knife, with knife tips that have a height H with respect to the lower edge of the knife running parallel to the cutting material.

Knives of the type mentioned above are common for printers, cash registers, validation devices and similar devices that enable the cutting of registration strips. In the case of partial cutting, the cutting material is severed except for a few webs, so that the cut strips can be easily separated at the perforations created in this way if necessary.

It is also known that with such devices the paper strips can be completely severed, for example after the end of a printing process, whereby the cutting material can consist of either paper or plastic film. Cutters are usually used to cut the registration strips, the blades of which have a certain number of triangular individual blades depending on the cutting width. An example can be seen in the enclosed Figure 1.

The well-known knife is driven by electric motors, the power and current consumption of which are designed depending on the material to be cut. Due to the increasing number of different applications, there is a need for high-performance

performance-optimized knives for printers, cash registers and validation devices, whereby due to the high volumes even a slight percentage improvement in performance is a significant advantage.

The present invention proposes a new blade shape for blades with a sawtooth profile, which enables more cost-effective operation in printers , cash registers and validation devices. A special arrangement of the blade tips, preferably in conjunction with an optimization of the base and slot shape, makes it possible to significantly reduce the amount of force required when cutting or perforating the cutting material and at the same time improve the functional reliability compared to conventional blade arrangements. This has been made possible in detail by the following measures:

The starting point for the considerations was the observation that the tips of the knife 3a simultaneously hit the cutting material during the cut, which results in a high power requirement when penetrating or perforating the cutting material. The drives required for these knives therefore have a correspondingly high power requirement, which in turn leads to a high power consumption of the cutter.

Due to the inventive design of the knife, the knife tips are not pressed into the cutting material at the same time, because the knife tips are no longer on a straight line running parallel to the paper guide.

Preferably, the blade tips are located on an imaginary circular arc or a stepped profile. The teeth can be set back individually as in Figure 3 or in pairs as in Figure 4. The bottoms of the separating slots between the blade tips are preferably located on a parallel line to the material being cut.

The invention is explained in more detail below using several exemplary embodiments. They show:

Figure 1 General view of a conventional

schneiders

Figure 2 to Figure 4 Knife designed according to the invention

in top view.

According to Figure 1, the knife 3 is mounted with a knife carrier 2 in a housing 1, wherein the knife is firmly connected to the knife carrier.

The knife carrier 2 with the knife 3 is moved in the direction of the arrow indicated by a gear not shown in Figure 1. Depending on the cutting conditions set, the knife can cut through the material 4 partially (perforation) or completely.

The cutting material is moved in a plane perpendicular to Figure 1 through the slot 5 of the housing 1. This can preferably be done by a transport device (not shown) controlled by the printer.

When the knife moves upwards, the tooth tips 3a would hit the cutting material at the same time as shown in Figure 1. For this common knife shape, a high force requirement is therefore to be expected, which in turn triggers a high power requirement.

Figure 2 now shows an inventive design of the knife tips, which are arranged in a circular arc on a line 6. The knife flanks 3b end on an imaginary line, which is referred to as the base 3c of the individual teeth.

As a further variant, the arrangement of the knife tips in a step shape is shown in Figures 3 and 4, whereby the base 3c still runs on a circular arc. In addition, the bottom of the slots is arranged on a straight line 3d, which

runs parallel to the lower edge of the knife D.

Figure 4 shows two variants with different shapes of the base 3c for the individual teeth. While in Figure 4a the base of the individual teeth is concave in relation to the lower edge of the blade D, in Figure 4b it is convex in relation to the lower edge of the blade D.

Since in the cases described above, when the knife is immersed in the cutting material, fewer knife tips are in operation at the same time than with a conventional knife shape, the power required for the cutting process is lower and thus the power consumption of a paper cutter is also more favorable.

An additional advantage of designing the knife shape according to Figure 4b is that even after the cutting process has ended, when the knife emerges from the cutting material, the raised knife tips 3g present on the knife side edges AB remain in engagement with the cutting material for a longer period of time, so that better guidance of the cutting material and avoidance of lateral distortion during paper transport could be determined.

The advantages of the cutter according to the invention are particularly evident with large cutting widths. Drive motors with significantly less power can be used here, which, due to their lower power consumption, generate less heat and therefore have a less disruptive effect on any electronic components that may be located in the immediate vicinity. Since the cutting process is carried out at different times over the length of the knife, irregularities in the paper quality or in the thickness of the cutting materials cannot lead to a disruption of the functional reliability. The cutting quality always remains uniform, since it is carried out in a point-like manner or at least on a short line, namely in the area of the side cutting edges.

Claims (8)

RUHLATEC Industrieprodukte GmbH 19. Dec. 1996 Neue Straße 67 MW/scb (allO245) 99846 Seebach P96581DE00 Blade with sawtooth profile Protection claims 1. Knife with a sawtooth profile, consisting of a plurality of triangular individual knives arranged at a lateral distance from one another on the knife front edge (C) with knife tips (3a, 3e) which have a height (H) with respect to the knife lower edge (D) running parallel to the cutting material (4), characterized, that the heights (H) of the knife tips (3e) are irregularly dimensioned. 2. Knife according to claim 1,
characterized, that the knife tips (3e) are arranged on an imaginary arc (6) which begins at the knife edges (AB), wherein the knife front edge (C) does not run in a straight line but rather curved or wavy in accordance with the arc shape. 3. Knife according to one of the preceding claims,
characterized, that the front edge of the knife (C) is concavely curved with respect to the lower edge of the knife (D). 4. Knife according to one of claims 1 to 2 , characterized in that the front edge of the knife (C) is convexly curved with respect to the lower edge of the knife (D). 5. Knife according to one of the preceding claims, characterized in that the knife tips (3f) have a different height (H ₁ , H ₂ ) individually or in pairs in a stepped manner. 6. Knife according to one of the preceding claims, characterized in that the base (3c) of the individual teeth, which is formed by the lower end points of the knife flanks (3b), lies on an arc at an irregular distance from the lower edge of the knife (D). 7. Knife according to one of the preceding claims, characterized in that the base (3c) of the individual teeth is convex or concave in relation to the lower edge of the knife (D). 8. Knife according to one of the preceding claims, characterized in that between two adjacent knife tips a slot with different slot depth is arranged, the side walls of the slots running vertically and a line (3d) drawn through all slot bottoms running parallel to the lower edge of the knife (D).