STATE OF THE ART It is known that in automatic packaging machines are currently employed cutting devices connected to thermosealing devices of films of flexible material. The cutting devices most frequently employed have rectilinear blade that is, in the first place, elastically pushed to press the films against a rigid element and it is then hit quickly to cause the instant cut by means of contrast with said rigid element. The resulting rectilinear cut is aesthetically preferred to of the uneven one that is obtained with traditional indented blades.

However, the devices performing sudden rectilinear cut have two inconveniences. The first is the noise caused by the frequent beats of the blade against the rigid contrasting element; the second inconvenience is the wearing of the cutting edge of the rectilinear blade, which is also caused by the frequent hitting of the blade against the rigid element.

In the most recent packaging machines the increase of productivity has made both these problems more urgent, and it is the combination of the two that limits the employment of sudden cut rectilinear blade devices.

The problem to be solved is exactly to be able to increase the frequency of the cuts avoiding the noise and the wear of the cutting edge of the rectilinear blade.

The proposed solution by the present invention maintains the aesthetic characteristics of the rectilinear cut but it eliminates the noise and wear problems.

The advantage offered by this industrial invention is to make noiseless the cutting operation of high performance packaging machines, at the same time extending the duration of the cutting edge of the rectilinear blade.

The realization of this invention becomes even more relevant when said improvements are applied during the high speed continuous functioning.

During intensive testing the noiselessness of the cutting operation and the duration of the cutting edge of the blade have proven very successful and particularly valid at high speed.

DESCRIPTION The invention is now disclosed with reference to the figures of the attached drawings.

Figure 1 represents under a partially sectioned plant view the structure of a cutting device consisting essentially by two opposite intermitting parts. It can be noticed that the contrasting element 3, easily interchangeable, is placed by the springs 2 upon the body 1. It should be also noticed that the cutter block element 8 is provided with a rectilinear blade 5, easily interchangeable, held by the inclined springs 7 against two elastic pivots 9 and 10.

Particularly relevant is the presence of the small roll 4 connected to the blade 5, that is held by the inclined springs 7 against the slanting plane 6, especially provided upon the body of cutter block 8. It should be made clear that in said figure 1 the cutting device is showed in the rest phase, that is the open position. Figure 2 represents the approaching device and one can notice that the blade 5 has not yet come in contact with the rigid contrasting element 3. The cutting action has not started and the blade is kept by the springs 7 with small roll 4 in contact with the inclined plane 6.

Figure 3 shows the active cutting phase and one can notice that the blade 5, getting in touch with the rigid contrasting element 3, comes back under the guidance of the elastic pivots 9 and 10. It should be pointed out that during this backward motion the blade slides also sideways because of the presence of the roll 4 that slides upon the slanting plane 6. The cutting action is obtained by sideways sliding of the rectilinear blade that happens without shocks thus noiselessly, even at high speed.

It is evident that, after having silently performed the cut, the device, before starting the following cycle, will reach again the rest position illustrated in figure 1.

Figures Ibis, 2bis and 3bis represent a technological variation in which the functioning is basically similar to figures 1, 2 and 3. One can notice the presence of two rolls 4 and 4'and of the two slanting planes 6 and 6'that actuate, by going and returning, the sideways sliding of the blade 5'. One can notice, eventually, that the springs 7'are not as inclined as the springs 7 and are used only to hold the blade 5'in contact with elastic pivots 9 and 10 that are inserted in the cutter block body 8'. In the figure 3bis, in particular, one can notice that during the backward motion the blade 5' performs also a sideways sliding, because of the presence of the roll 4 that slides upon the slanting plane 6 and performs a noiseless and shock-less cut. In the following opening phase the blade ejected outwards by the elastic pivots 9 and 10 is sideways withdrawn not by the springs 7'that are not inclined but by the roll 4'that is engaged against the slanting plane 6' present in the cutter block element 8'.

In all the figures each single detail is marked as follows: 1 is the body that carries the contrasting rigid element.

2 indicates the withdrawal springs.

3 is a contrasting rigid element that is easily removable.

4 is a small roll connected to an extremity of the cutting blade.

5 is the rectilinear edge blade.

6 is the inclined plane upon which the roll 4 slides.

7 indicates the inclined withdrawal springs that, besides holding the blade 5 in the seat of the body 8, bring also the blade back in rest position when the device, after having performed the sideways sliding cut, is reopened in the rest position getting ready for a new cycle.

8 indicates the body of the cutter block device.

9 indicates the buffer spring of the elastic pivots.

10 indicates the elastic pivots.

4', 5', 6', 7'and 8'indicate the similar stances of the variation presented in the figure Ibis, 2bis and 3bis.

The clearness of the figures shows the simplicity of the functioning of the device.

The improvement consists in the introduction of the roll 4, connected to the blade, and in ( ?) its corresponding slanting plane 6 upon the cutter block element 8.

These are the two original elements that during the cutting action exert on the blade also a sideways sliding movement. It is exactly this blade sliding, performed automatically by the slanting plane without the employment of any mechanism, that optimizes the cutting action with a surprising practical effect that allows the realization of a rectilinear clear cut without noise and wear.

The figures also highlight the simplicity, reliability and convenience of realization of the invention, that is the result of a complex experimental process. The invention allows of course for several variations of practical realization as far as the dimensioning and structural proportioning of each single detail that is included in the improved cutting device.

All the cutting devices having a rectilinear blade provided with a roll, and having a cutter block provided with a corresponding slanted plane, as basically described, illustrated and hereinafter claimed, will be considered part of the present invention.