UNWINDER FOR PAPER CONVERTING

Abstract

Unwinder for paper converting, comprising a support (1) adapted to support a reel (B) from which a web of paper material is unwound and comprising dragging means acting by contact on said reel (B) and adapted to impose a rotation of the reel coil about the respective longitudinal axis (x) with a predetermined speed, the diameter of the reel (B) varying while the latter rotates. The dragging means have a variable configuration. The unwinder comprises reconfiguration means adapted to vary the configuration of the dragging means on the basis of the instantaneous diameter of the reel (B) and control means (5; EU) adapted to control said reconfiguration means such that the contact between the reel (B) and control the dragging means takes place on a contact area (200) having an angular extension (a) substantially constant while the diameter of the reel (B) varies.

Description

The present invention concerns an unwinder for paper converting.

It is known that an unwinder is an apparatus intended to support the parent reels that feed the paper webs used for making paper logs from which are obtained, by way of example, toilet paper rolls or kitchen paper rolls etc. after the passage of the paper webs through suitable machines such as embossers, rewinders and cutting machines located downstream of the unwinders.

Generally, an unwinder of the type indicated above comprises a support for the reel that feeds the paper web and a plurality of belts enslaved to a respective motor which, acting by contact on the paper of the reel, drag the tape that, therefore, unwinds along the direction of the same belts at a predetermined speed.

Since the diameter of the reel gradually decreases while that the paper unwinds from the reel, there is the need to ensure a proper contact between the belts and the reel in such a way that the belts can follow this variation in diameter.

The main purpose of the present invention is to provide a mechanism allowing to change the configuration of the driving belts of the unwinder while the diameter of the parent reel changes, without coming into mechanical or structural complications which would reduce its utility. This result is achieved, according to the present invention, by providing a device having the features indicated in claim 1. Other features of the present invention are the subject of the dependent claims.

An unwinder in accordance with the present invention allows to adapt the configuration of the drive belts to the variable diameter of the parent reel in a particularly simple and effective way. Furthermore, an unwinder in accordance with the present invention is relatively cheap in relation to the advantages offered.

These and other advantages and features of this invention will be best understood by anyone skilled in the art thanks to the following description and to the attached drawings, provided by way of example but not to be considered in a limitative sense, wherein:

FIGS. 1-6 schematically show, in side view, an unwinder in accordance with the present invention in a sequence of configurations assumed starting from an initial time in which the diameter of the parent reel is maximum (FIG. 1) until a final time in which said diameter has a minimum value (FIG. 6);

FIG. 7 is a simplified diagram of a possible system for controlling the movement of the carriages that carry the follower pulleys;

FIG. 8 is an enlarged detail of FIG. 3;

FIG. 9 is similar to FIG. 6. but it shows, in particular, a possible system for moving the carriages (240, 250).

Reduced to its basic structure and with reference to the attached drawings, an unwinder (S) according to the present invention comprises a support (1), on which can be placed a parent reel (B), equipped with stop collars (10). Each of the collars (10) defines a constraint for a corresponding pin (P) inserted in a respective side of the reel (B). When the reel (B) is laid on the support (1), the collars (10) are open. During the unwinding step, that is, while the reel (B) rotates about its own axis (x) and about the axis of the pins (P), the collars (10) are closed (as in FIGS. 1-6). When the reel (B) is exhausted and must be removed from the support (1) to be replaced with a new one, for example by means of a bridge crane or any other suitable handling means, the collars (10) are open again. The support (1), as well as the collars (10) and the pins (P) inserted in the parent reel (B) are of the type known to those skilled in the art and, therefore, are not described in greater detail.

Moreover, the unwinder (S) comprises a plurality of ring-closed belts (2) driven by pulleys (20, 21, 22, 23, 24, 25) with two pulleys (20, 21) placed at corresponding fixed positions, one pulley (22) also placed at a fixed position and connected with an electric motor so as to act as a driving pulley, a tensioning pulley (23) applied on a shaft that can be moved horizontally by means of a respective actuator (300) solid to an underlying fixed base (4), and two follower-pulleys (24, 25) whose distance from the longitudinal axis of reel (B) is constant. More particularly, the follower-pulleys (24, 25) are placed each on a corresponding carriage (240, 250) that is free to slide along a guide (241, 251) radially oriented with respect to the axis of reel (B), i.e. oriented radially with respect to the collar (10). In FIGS. 31-36 the belts are represented by dashed lines to better show their configuration. As shown in FIGS. 1-6, said guides (241, 251) are on opposite sides with respect to the collar (10) and are diagonally oriented with opposite inclination angles, such that their respective upper ends are turned towards the center of the collar (10) provided on the support (1). In other words, the guides (241, 251) are oriented with their upper ends converging radially towards the center of the collar (10) where the longitudinal axis of the reel (B) passes. The carriages (240, 250) are operated by an electric motorgear (260) that is shown in FIG. 7 and FIG. 9 only. The output shaft of the motorgear (260) drags two chains (270, 280) driven by corresponding driving pulleys (271, 281). The chains (270, 280) and the motorgear (260) are inside the guides (241, 251), that is, within the space delimited by said guides. Each carriage (240, 250) is connected, on its lower side, to a corresponding chain (270, 280). The points where the carriages (240, 250) are connected to the chains (270, 280) are denoted by reference numerals (272) and (282).

As shown in the drawings, the pulleys (20, 21, 22, 23, 24, 25) are arranged in such a way that the belts (C2) are below the reel (B).

On a carriage (240) there is mounted a photocell (5) whose optical axis is directed towards the reel (B). The position of the photocell (5) on the carriage (240) is fixed. For simplification, the photocell (5) is shown only in FIG. 1 and in the block diagram of FIG. 7. The light beam generated by the photocell (5) is intercepted by the reel (B) as long as the distance between the same photocell (5) and the reel (B) is equal to a predetermined value (first operating condition).

When, due to the decrease in diameter of the reel (B) caused by the unwinding of the paper web, the distance between the photocell (5) and the reel (B) exceeds the predetermined value, the light beam is no longer intercepted by the reel (B) and this corresponds to a second operating condition.

In the first operating condition, the carriages (240, 250) and the related pulleys (24, 25) are stationary.

In the second operating condition, the carriages (240, 250) are approached to the reel (B), i.e. they are raised synchronously along the respective guides (241, 251), until the restoration of the first operating condition. Simultaneously the actuator (300) moves the pulley (23) to maintain the proper tension on the belts (2) while the configuration of the latter changes.

For this purpose, the photocell (5) is connected to a control unit (UE) which controls the motor (260) and is equipped with a keyboard (PS) in order to set the aforesaid distance to the desired value.

In this way, while the diameter of the reel (B) decreases, there is always a branch (200) of the belts (2) that copies the lower side of the same reel (B) and has an angular amplitude (a) substantially constant, the angle (a) being observed between the axis (x) of the reel (B) or the axis of the respective pin (P) and the contact points of the upper branch (200) of the belts (2) with the reel (B) as shown in FIG. 8.

In practice, the distance (d) between the follower-pulleys (24, 25) and the reel (B) remains constant while the paper web unwinds from the reel (B). Yet in other words, the upper branch (200) of the belts (2) follows the variation in diameter of the reel (B) because it raises and copies the lower side of the latter.

Therefore, regardless of the diameter of the reel (B) during the unwinding of the paper, the belts (2) always act in an optimal way on the same reel, copying perfectly the profile of the latter in the area (200) where they exert the drag action.

By way of example, the initial diameter of the reel (B) is 3000 mm and the final diameter is 500 mm.

The photocell (F5) may be replaced by any other device suitable to detect the distance of the carriage (240), and then the photocell (F5), from the reel (1).

The photocell (5) may be replaced by any other device suitable to detect the distance of the carriage (240), and then the photocell (5), from the reel (B).

Therefore, the unwinder described above comprises:

• • dragging means with variable configuration which act by contact on a reel (B) and are adapted to cause a rotation of the same reel about the respective longitudinal axis with a predetermined speed;
  • reconfiguration means adapted to vary the configuration of said dragging means in function of the instantaneous diameter of the reel (B);
  • control means (5; UE) adapted to control the means of reconfiguration such that the contact between the reel (B) and said dragging means is provided on a contact area (200) of substantially constant angular amplitude (a) while the diameter of the reel (B) varies.

According to the example described above the dragging means with variable configuration are constituted by the belts (2); the means of reconfiguration of the driving means are constituted by the carriages (240, 250) with the relative pulleys (24, 25); and the control means are constituted by the photocell (5) and the programmable unit (UE). Furthermore, according to the example described above the dragging means are placed below the support (1) so as to act on the lower side of the reel (B).

In practice the execution details may vary in any equivalent way in relation to the elements described and shown in the drawings, without departing from the adopted solution idea and then remaining within the limits of the protection granted by the present patent.

Claims

1. An unwinder for paper converting, the unwinder comprising:

a support adapted to support a reel from which a web of paper material is unwound;

a dragging means acting by contact on said reel for imposing a rotation of the reel about a respective longitudinal axis of the reel with a predetermined speed, a diameter of the reel varying while the reel rotates, said dragging means having a variable configuration, and said dragging means comprising a reconfiguration means for varying the variable configuration of said dragging means based on an instantaneous diameter of the reel; and

a control means for controlling said reconfiguration means such that contact between the reel and the dragging means takes place on a contact area having an angular extension substantially constant while the diameter of the reel varies.

2. An unwinder according to claim 1, wherein said dragging means is moved radially toward the longitudinal axis of the reel while the diameter of the it reel decreases.

3. An unwinder according to claim 2, wherein said dragging means is constrained to carriages that slide along corresponding guides oriented radially with respect to the longitudinal axis of the reel.

4. An unwinder according to claim 1, wherein said dragging means is placed below said support.

5. An unwinder according to claim 1, wherein said dragging means comprises belts.

6. An unwinder according to claim 5, wherein said belts are wound on a plurality of pulleys the plurality of pulleys comprising a driving pulley and two movable pulleys, the two movable pulleys being located at a distance from an outer surface of the reel, wherein the distance is constant.

7. An unwinder according to claim 6, wherein said two movable pulleys are applied on carriages.

8. An unwinder according to claim 1, wherein said control means comprises an optical means for detecting a distance between a point where the optical means is mounted and the reel.

9. An unwinder according to claims 8, wherein said optical means is a photocell means.

10. An unwinder according to claim 8, wherein said optical means is mechanically associated with said dragging means.

11. An unwinder according to claim 3, wherein said optical means is associated with one of said carriages.

12. An unwinder according to claim 8, wherein said optical means is associated with one of a plurality of carriages.

13. An unwinder according to claim 10, wherein said optical means is associated with one of a plurality of carriages.