ITMI20120724A1 - POWER SUPPLY AND CUTTING GROUP FOR A DISPENSER OF PAPER SHEETS OBTAINED FROM A CONTINUOUS TAPE - Google Patents

Description

FEEDING AND CUTTING GROUP FOR A DISPENSER OF PAPER SHEETS MADE FROM A CONTINUOUS BELT

The present invention relates to devices for the controlled delivery of portions of paper from a continuous belt for use as towels, and in particular to a dispenser of the manually operated type in which the traction exerted by the user on the paper flap protruding from the dispenser which controls the feeding of a predetermined section of tape and its cutting. In the following, specific reference will be made to a paper towel dispenser, but it is clear that what has been said can be applied with the obvious modifications to toilet paper, kitchen paper and the like.

Paper towel dispensers made from a continuous belt are well known in which the cutting blade is fixed and the user only has to bring the strip of paper extracted from the dispenser against it, to separate it from the belt and be able to use it . This type of device, described for example in JP 2006034596, is very simple and reliable but leaves the user both the feeding function, i.e. the choice of the length of the strip to be cut with consequent inevitable waste, and the function of cutting, which presupposes the presence of a blade in an area that is always accessible to the user and therefore potentially dangerous.

A natural evolution of this device is the automatic paper cutting, always with manually operated devices and without resorting to motorized solutions which are much more expensive, more bulky and less reliable.

An example of this type of device is that in which a blade actuation cam is provided, connected to the paper web feed roller, to make it snap radially from a rest position inside a longitudinal slot made in the roll itself to a cutting position in which it interferes with the paper outside said roll. It is clear the danger of a possible snap on the outside of the blade when the user manually performs the operations of inserting the paper on the feed roller, moreover the snap mechanism is noisy both during the cutting phase and when the machine returns. blade in rest position. An example of this type of cutting mechanism is described in GB 837194.

Another type of device similar to the previous one is that in which the blade acts on the edge of paper in a radial direction from the outside towards the inside of the feed roller, penetrating into a longitudinal slot of this. In this case the blade is mounted on a cutting mechanism by means of a fork hinged and guided laterally to be operated in synchrony with the rotation of the roller, and an example of this device is described in the previous application of the applicant n. WO 97/36531. Although it is safer, even this solution still implies a rather noisy mechanism as well as rather complex and therefore expensive and not entirely reliable. Furthermore, the presence of the cutting mechanism outside the feed roller makes the device more bulky.

A different type of cutting mechanism is that in which a first blade is mounted on the feed roller and a second blade is fixedly mounted on the roller support structure in a position of interference with said first blade carried by the roller. Also in this case, while obtaining a simpler and more compact device, there is always the problem of the presence of a blade in an accessible and therefore potentially dangerous area when the user manually performs the operations of inserting the paper on the roller. Power supply. Furthermore, the contact between the two blades causes their wear and the effectiveness of the mechanism is closely linked to avoiding play that could reduce or cancel the interference between the blades. Examples of this type of cutting mechanism are described in EP 693268 and EP 930039.

In order to overcome the problems of noise, safety, bulk and reliability of the devices described above, cutting mechanisms have more recently been developed comprising a blade which is rotatably housed in the feed roller and acts with an oscillatory movement controlled by the rotation of said roller. Examples of this type of cutting mechanism are described in WO 2006/30138 and WO 2007/17603, which both illustrate a blade-holder shaft provided at one end with a toothed sector which acts as a rack and during the rotation of the feed roller periodically engages with a corresponding fixed toothed sector, obtained on the roller support structure, which acts as a pinion.

In this way, the blade performs a partial rotation to exit the roller during the cutting phase defined by the arc of meshing of the two toothed sectors and then rotates backwards in the feed roller under the action of a recall when said toothed sectors are disengaged. Although this solution is effective from the point of view of safety and space, it still has drawbacks in terms of noise, reliability and smooth operation.

A first drawback derives from the fact that the engagement and disengagement of the toothed sectors at each operating cycle requires perfect synchronization of the rotation of the blade holder shaft and of the feed roller to avoid jamming of the mechanism and premature wear of the initial teeth. that start the meshing. In fact, for this purpose, WO 2006/30138 provides that the rack and the pinion are provided with a pulley and that a belt is always stretched between said two pulleys to synchronize their movement. This obviously implies a rather complex, expensive and scarcely reliable structure since a loosening, slippage or wear of the belt is sufficient to adversely affect the smoothness of operation.

A second drawback resides in the noise due to the return of the blade to the rest position due to the effect of the return spring, and in this regard WO 2007/17603 provides that the rack and the pinion are provided with corresponding cam surfaces which slide one on the other during the re-entry of the blade to slow it down and reduce the noise. Also this expedient implies a greater complexity of the mechanism which, being also subject to wear due to sliding over time, will end up being noisy.

Yet another intrinsic drawback to the periodic meshing of the toothed sectors, even in conditions of perfect efficiency of the mechanism, is given by the variation of the resistance of the mechanism in the various phases of the operating cycle which translates into less fluidity of operation and a inconvenience for the user. In fact, at the beginning of traction on the protruding edge of paper, the user encounters minimal resistance as the rack and pinion are not engaged, then the resistance increases when meshing and decreases again when they disengage.

Finally, it must be considered that the presence of toothed sectors only at one of the two ends of the feed roller inevitably implies an imbalance in the forces acting on the mechanism, and this imbalance negatively affects the smoothness of operation, especially if the traction exerted by the mechanism user is not centered.

The object of the present invention is therefore to provide a feeding and cutting unit for a paper towel dispenser which overcomes the aforementioned drawbacks.

This purpose is achieved by means of a feeding and cutting unit in which the blade-holder shaft housed in the feeding roller is provided at at least one end, preferably both, with a toothed wheel which acts as a rack and is constantly engaged with a corresponding fixed toothed wheel, obtained on the support structure, which acts as a pinion. Other advantageous characteristics are reported in the dependent claims.

A first important advantage of this group lies in the greater reliability and smoothness of operation guaranteed by the constant meshing of the rack with the pinion, so that there are no problems of synchronized rotation of the blade holder shaft and of the feed roller regardless of the play. or from wear that may arise over time. In this way, moreover, the resistance of the mechanism in the various phases of the operating cycle is substantially constant, since the gear is always engaged, and requires less effort from the user thanks to the greater fluidity of operation.

A second significant advantage of this group consists in the elimination of the blade return spring, with consequent noise reduction and simplification of the group which is more economical. It should be noted that the simplification also derives from being able to do without the belt transmission and the cam profiles described in the prior art mentioned above.

Another advantage of the unit in question is its ability to operate effectively even with paper of heavier weight than expected since the cut is performed on the maximum possible arc of rotation of the feed roller, and therefore for the maximum time, while in the oscillating blade mechanisms a part of the rotation arc is occupied by the return stroke of the blade which may not have time to complete the cutting of a heavier paper than that for which the unit was designed.

Yet another advantage of the aforementioned unit, in its preferred embodiment with a gear at each end, derives from the symmetry of the forces on the cutting mechanism even in the case of eccentric traction exerted by the user, which results in greater reliability and fluidity. of operation.

These and other advantages and characteristics of the feeding and cutting unit according to the present invention will become evident to those skilled in the art from the following detailed description of an embodiment thereof with reference to the attached drawings in which:

Fig.1 is an exploded perspective view of the main components of the feeding and cutting unit;

Fig.2 is a perspective view of the unit of Fig.1 in assembled condition, but without the components on the left and the front protection for clarity of the drawing;

Fig.3 is a front view of the unit of Fig.1 in assembled condition, but without the front protection;

Fig.4 is a right side view of the group of Fig.1 with a roll of paper whose end edge passes through said group and exits below;

Fig.5 is a front view similar to the previous one;

Fig.6 is a left side view similar to the previous one with the addition of the rotation completion spring;

Fig.7 is a sectional view along the line A-A of Fig.5 which better illustrates the path of the paper web through the feeding and cutting unit; And

Figures 8-15 are schematic views similar to the previous one illustrating an operating cycle.

Referring first to Figures 1 to 5, it can be seen that the feeding and cutting unit for a paper sheet dispenser according to the present invention substantially comprises a rear support element 1 with vertical end seats for the insertion of the shoulders left 2 and right 3 side panels between which a feed roller 4 is rotatably supported, formed by two half cylinders 4a and 4b, which in turn rotatably supports inside it a shaft 5 parallel to it which carries a toothed blade 6 which , during a part of the rotation of the shaft 5, it protrudes through a corresponding longitudinal slot formed in the roller 4 as better illustrated below.

The rotation of the blade-holder shaft 5 is obtained as a consequence of the rotation of the roller 4 by means of at least one end gear, preferably two as illustrated in the figures, formed at least by a toothed wheel 7, integral and coaxial to the shaft 5 , which engages a corresponding toothed wheel 8 obtained on the internal side of the relative left 2 and right 3 side in a coaxial position with the rotation axis of the roller 4.

A contrast shaft 9 is also rotatably supported between the sides 2, 3 with an axis of rotation parallel to the axis of rotation of the feed roller 4 and in a position such as to be in contact with pre-load with the portion higher than the latter. The sides 2, 3 carry respectively on their external sides a ratchet 10 and a manual reset knob 11 which are integral with the respective opposite support pins of the roller 4. A front protection 12 is finally mounted on the sides 2, 3 and provided, preferably in a central position, with a spur 12a which is inserted into a corresponding groove obtained on the roller 4 so that the paper web is surely deflected outside the dispenser by the spur 12a if the web remains adherent to the roller 4 even beyond the angular position of rotation corresponding to the outlet slot.

With reference also to figures 6 and 7, it can be seen that the roller 4 can rotate only counterclockwise (seen from the left) since the ratchet 10 located on the external side of the left side 2 is mounted so that the stop 10a hinged on said side 2 prevents the clockwise rotation of the serrated wheel 10b integral with the left pin of the roller 4. Obviously in another embodiment other than the one illustrated, the rotation could only be clockwise if necessary, it would be enough to reverse the arrangement of the ratchet 10.

Fig.6 also illustrates a spring 13, arranged between a pin of the serrated wheel 10b and a pin obtained on the side 2, which completes the rotation of the roller 4 so that the cut is smooth and light, being performed more by the force of the spring 13 which by the traction of the user on the end flap L of the roll R which protrudes from the dispenser below. Furthermore, the spring 13 ensures that an end edge L of the tape protrudes from the dispenser for the next user.

As shown in the sectional view of Fig. 7, the paper ribbon coming from roll R is first wound on the front of the contrast shaft 9 then it is inserted between the latter and the feed roller 4, so to pass on the back of the roller 4 and exit at the bottom through the slot between the latter and the rear support 1. The blade-holder shaft 5 rotates inside the roller 4 around its own axis of rotation, which at in turn, it rotates together with the roller 4 around the axis of rotation of the latter so that the blade 6 protrudes from it by approximately half a turn starting from the angular position illustrated in Fig.7.

The simple and effective operation of this device is easily understood from the above description, as is now illustrated with the aid of figures 8 to 15 in which the blade-holder shaft 5 has been omitted to show more clearly how the rotation of the blade 6 is due to the constant engagement of the toothed wheel 7 and of the toothed wheel 8 which form the end gear.

During the device loading phase, the continuous paper ribbon unwound from the roll R is inserted at the front between the contrast shaft 9 and the roller 4 which is rotated by means of the knob 11 until the end flap L comes out. The user pulls the flap L, this causes the rotation of the roller 4 which carries the shaft 5 whose toothed wheel 7 engages the toothed wheel 8 in turn causes the rotation of the shaft 5 and therefore of the blade 6.

From the rest position of Fig. 8 in which the blade 6 is located on the front of the roller 4 (position at three o'clock) and is turned inside the latter, in the first phase of the operating cycle the rotation simultaneous of the roller 4 and the shaft 5 carried by it leads to the position of Fig. 11, substantially coinciding with Fig. 7, in which the blade 6 is located a little further back than the top of the roller 4 (position at eleven o'clock) and begins to protrude through the longitudinal slit of the latter.

The cutting of the paper tape takes place along about a quarter of a turn in the second phase of the operating cycle between the position of Fig. 11 and the position of Fig. 13, in which the blade 6 is located a little lower than the back of roller 4 (eight o'clock position) and protrudes substantially perpendicular therefrom. At this point, usually, the end flap L has already been cut from the rest of the belt so as to form a towel T available to the user. However, in the case of paper that is more resistant to cutting, the detachment of the towel T can also take place further downstream from the position of Fig. 13 since the blade 6 continues to exert its cutting action until the ribbon comes out of the capacity of the blade 6 away from the roller 4.

In the third phase of the operating cycle of the unit, with the aid of the spring 13 as illustrated above, the roller 4 and the blade 6 complete their rotation to return to the rest position of Fig. 8 passing through the positions illustrated in the figures 14 and 15. The presence of the ratchet 10 prevents a possible reverse rotation of the roller 4 at the end of the rotation under the thrust of the spring 13, and therefore the exit of the end flap L is ensured for traction by the next user .

It is clear that the embodiment of the feeding and cutting unit according to the invention described and illustrated above constitutes only an example susceptible of numerous variations. In particular, to obtain greater â € œ aggressiveness â € in the cut by making the blade 6 come out of roller 4 in the opposite direction to that of the paper web advancement (ie clockwise in the example shown), the the extremity could also comprise a third toothed wheel interposed between the toothed wheels 7, 8 and also carried by the roller 4 so as to reverse the rotation of the blade-holder shaft 5.

Similarly, if the overall transmission ratio between the toothed wheel 7 and the toothed wheel 8 is different from the 1: 1 ratio of the illustrated embodiment, other variations are possible. For example, if shaft 5 makes only half a turn at each rotation of roller 4 (ratio 1: 2) there could be two opposing blades 6 along the circumference of shaft 5, or a double-length T towel could be dispensed if blade 6 is always single.

Claims (8)

CLAIMS 1. Feeding and cutting unit for a dispenser of sheets of paper obtained from a continuous ribbon wound in a roll (R), comprising a support structure (1, 2, 3) which rotatably supports a feed roller (4) which in turn, it rotatably supports a shaft (5) parallel to it which carries at least one blade (6) which, during the rotation of said blade-holder shaft (5), protrudes through a corresponding longitudinal slot made in said feed roller (4 ), characterized by the fact of comprising at least one end gear constantly in engagement formed by at least a first toothed wheel (7) integral and coaxial with the blade-holder shaft (5) and a second toothed wheel (8) obtained on said structure support (1, 2, 3) in a coaxial position with the rotation axis of the feed roller (4). 2. Feeding and cutting unit according to claim 1, characterized in that it further comprises a second gear at the end which is constantly engaged, identical to said first gear (7, 8) and located at the opposite end. 3. Feeding and cutting unit according to claim 1 or 2, characterized in that the transmission ratio of the gear is 1: 1. 4. Feeding and cutting unit according to one of the preceding claims, characterized in that the end gear comprises a third toothed wheel interposed between the first two toothed wheels (7, 8) and also carried by the feeding roller (4). 5. Feeding and cutting unit according to one of the preceding claims, characterized in that it also comprises a contrast shaft (9) rotatably supported by the support structure (1, 2, 3) with a rotation axis parallel to the rotation axis of the feed roller (4) and in a position such as to be in contact with the upper portion of the latter. 6. Feeding and cutting unit according to one of the preceding claims, characterized in that it further comprises a front protection (12) mounted on the support structure (1, 2, 3) and provided, preferably in a central position, with a spur (12a ) which is inserted into a corresponding groove obtained on the feed roller (4) so that the paper web is surely deflected outside the dispenser by said spur (12a) if the web remains adherent to the feed roller ( 4) even beyond the angular rotation position corresponding to the dispenser outlet slot. 7. Feeding and cutting unit according to one of the preceding claims, characterized in that it further comprises a ratchet (10) and a manual reset knob (11) which are integral with respective opposite support pins of the feed roller (4). 8. Feeding and cutting unit according to the preceding claim, characterized in that it also comprises a spring (13) arranged between a pin obtained on the ratchet (10) and a pin obtained on the support structure (1, 2, 3) and adapted to complete the rotation of the feed roller (4) so as to ensure that an end edge (L) of the belt protrudes from the dispenser for the next user.