Apparatus for causing paper webs to tear off within rewinding machines

Abstract

Apparatus for causing paper webs to tear off within rewinding machines, the web (2) being provided, at regular intervals, with transverse perforation which subdivide the web into sheets joined to each other but able to be separated in correspondence of said perforation lines, the apparatus comprising a device to cause the tearing of the web (2) upon the passage of a perforation line (p) which separates the last sheet of a log (RO) in the course of formation from the first sheet of the next log to be formed, characterized in that the tearing device is a pneumatic type device (SP) able to direct a jet of compressed air toward the line (p).

Description

FIELD OF THE INVENTION

The present invention pertains to an apparatus for causing paper webs to tear off within rewinding machines.

BACKGROUND OF THE INVENTION

The production of logs is known to imply feeding a continuous web of paper along a predetermined path. At a given point of said path, a discontinuous transverse cut is operated on the web in order to subdivide it into sections or sheets of preset length which can be torn off.

This procedure comprises using tubular cardboard elements (commonly said “cores”) on the surface of which a preset amount of glue is spread to allow gluing the first sheet of the log to be formed. The procedure also provides for using winding rollers which drive into rotation the core on which the paper is wound. The log-forming process ends up when a preset amount of paper has been wound on the core. At this point, the formation of the next log begins. At the end of the formation process, it is necessary to glue the last sheet of each log on the underlying sheet to avoid the spontaneous unwinding of the same log. This type of gluing is defined as “edge closing”. When a number of preset sheets result wound up on the log in the course of formation, the paper web is cut off, that is, the last sheet of the log in the course of formation is separated from the first sheet of the next log to be formed.

Patents EP 524158, GB 210568 and EP 694020 disclose devices used to cause the paper web to tear off at the end of the formation of the logs.

Such devices, however, are not suitable for the present production requirements, as they are relatively unreliable or require frequent and costly service interventions.

SUMMARY OF THE INVENTION

An object of the present invention is to overcome, or at least greatly reduce, the above drawbacks.

The advantages deriving from the present invention lie essentially in the fact that it is possible to ensure all the time the highest accuracy in causing the paper to tear off whatever the feeding speed, by eliminating abrupt movements and consequent vibrations that are likely to endanger the proper operation of the system; that an apparatus according to the invention is relatively easy to make, cost-effective as far as the maintenance is concerned, and reliable even after a prolonged service life.

The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying drawings and descriptive matter in which preferred embodiments of the invention are illustrated.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is a schematic view of a rewinding machine provided with an apparatus according to one embodiment of the invention;

FIG. 2 is a schematic view of a rewinding machine provided with an apparatus according to another embodiment of the invention;

FIG. 3 is an enlarged schematic view of FIG. 1 showing the step of tearing the paper web;

FIG. 4 is enlarged schematic view of FIG. 2 showing the step of tearing the paper web;

FIG. 5A is a longitudinal section view of a first exemplary embodiment of a tear-off apparatus, according to the invention, which operates according to the layout of FIGS. 1 and 3;

FIG. 5B is a side view of FIG. 5A;

FIG. 5C is a partial side view of the tubular jacket of the apparatus shown in FIG. 5A;

FIG. 5D is a schematic cross-sectional view of the tubular jacket shown in FIG. 5C;

FIG. 6A is a schematic longitudinal section view of a second exemplary embodiment of an apparatus, according to the invention, which operates according to the layouts of FIGS. 2 and 4;

FIG. 6B is a partial side view of the external roller of the apparatus of FIG. 6A;

FIG. 6C is a cross sectional side view of the apparatus of FIG. 6A;

FIG. 6D is an enlarged view showing a detail of FIG. 6C; and

FIG. 7 is a block diagram of the system for operating the devices illustrated in the preceding figures.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to the drawings in particular, FIGS. 1 and 2, an apparatus according to the invention can be used within a rewinder of any possible construction, as far as the feeding and gluing of the cores (1) and paper webs (2) being used for the production of logs are concerned. Rewinding machines are known to those skilled in the art and, therefore, will not be described herein in details. U.S. Pat. No. 4,487,377, EP 524158, GB 2105688, U.S. Pat. No. 5,979,818 and EP 694020 describe as many examples of embodiments of rewinding machines, so that, reference can be made thereto for a broader description of this type of machines. Essentially, and in the same way as illustrated in FIGS. 1 and 2 of the attached drawings, they comprise:

a station (A) for feeding the cores (1);

a store (M) for the cores (1),

means for feeding and transversally perforating a paper web (2), with the use of a plurality of feeding, driving-out, and cutting rollers (R1, R2, R3, RA) disposed along a predetermined path;

means for wrapping up the paper (2) onto the cores (1), with the use of a set of winding rollers (RA, R4, R5) two of which (R4, R5) being disposed one above the other at the outlet of a channel (c) delimited in part by a fixed guide consisting of two elements (3a, 3b), in part by a loop-closed conveyor belt (300), and in part by a roller (RA) which contributes both to the supply of paper (2) and the winding of the latter onto the cores (1) (differently from the rollers which contribute only to the feeding and transverse perforation of the web 2);

pusher means (6) rotating about respective axes (60) disposed along the channel (C) for cooperating to the transfer of cores (1) from the store (M), that is, from the inlet station (A), to the first length (3a, 300) of channel (C), and to the transfer of the same cores from the first length of channel (C) to the second length (delimited by the guide element 3b and by the roller RA); and

means (not shown for the sake of simplicity in the figures of the attached drawings) for the gluing of the paper web (2) and cores (1) to cause the first sheet of each log (RO) to adhere on the corresponding core, and the last sheet of each log (RO) to adhere on the underlying paper.

With a procedure known to those skilled in the art, the web (2) unwinds along the delimited path from the rollers (R1, R2, R3, RA) and winds up onto the core (1r) in the station where the rollers (R4) and (R5) are positioned and, in cooperation with the roller (RA) and by rotating about the respective longitudinal axes, cause the paper (2) to wind up onto the core (1r). When a preset number of sheets (each of which being delimited by two consecutive transverse perforations of web 2) are wound up on said core, means are made to act for causing a tear of the web (2) at a site of the channel (C) located between a fresh core (1), being introduced into the same channel (C), and the station for the formation of logs (RO) wherein the rollers (R4, R5) operate. The tear is carried out in correspondence of a perforation line (p) which separates the last sheet of the log (RO) in the course of formation from the first sheet of the next log to be formed. Afterwards, the roller (R4), which is mounted on a rotating arm (400) associated with a corresponding actuator (401), is moved away from the underlying roller (R5) to release the log (RO) and making it to move away along an escape plane downstream (402). At this point, the core (1) which, while the formation of the log (RO) is being completed, moves forward and rolls along the channel (C) owing to the contact thereof with the roller (RA), the same core takes up the place of the preceding one and the cycle is identically repeated.

It is understood, however, that in view of the object of the present invention, the feeding, perforation, gluing and unloading means may be shaped and disposed in any way.

Advantageously, according to the invention, to cause a tearing of the web (2) in correspondence of the transit of a perforation line (p) which separates the last sheet of the log (RO) in the course of formation from the first sheet of the next log to be formed, means (SP) are provided able to direct a jet of compressed air toward the line (p) thereby causing—with the possible cooperation of the roller (R4) which, in a previous step, may be accelerated to stretch the web (2) in the region interested by the jet—the tearing of the web (2) in correspondence of the same line (p).

For example, reference being made to FIGS. 1, 3, 5A-5D of the attached drawings, the pneumatic means (SP) comprise a set of nozzles (7) associated, via corresponding solenoid valves (70), with a reservoir of compressed air (71): the nozzles (7), together with the respective solenoid valves (70) and reservoir (71) being positioned inside the roller (RA) whose outer surface is delimited by a tubular jacket (72) exhibiting a plurality of holes (73) through which the nozzles (7) are able to operate.

According to the example shown in FIG. 5A, the tubular jacket (72) rotates about its longitudinal axis while the reservoir (71) is fixed and coaxial to the same jacket (72).

To this end, as illustrated in FIG. 5A, the jacket (72) is provided with a shaft (8) with flanged head (87), which shaft is supported by the stationary part (80) of the machine with the interposition of a bearing (81), and is associated with a corresponding driving means (not shown).

Internally, the flange (87) has a seat for a conical casing (82) inside which an axial extension of the reservoir (71) is housed with the interposition of a corresponding bearing (83).

On the opposite side, the reservoir (71) is solid to a stationary part (84) of the machine and has a sleeve (85) positioned thereon, the latter having the jacket (72) coaxially mounted thereon with the interposition of a corresponding bearing (86).

In the drawing of FIG. 5A, the reference numbers (74) and (75) designate, respectively, the power cables for the solenoid valves (70) and a pipe for the introduction of air into the reservoir (71).

The solenoid valves (70) are activated to allow a flow of compressed air from the reservoir (71) through the nozzles (7), upon the transit of a perforation line (p)—separating the last sheet of the log in the course of formation from the first sheet of the next log to be formed—which takes place when the cutting rollers (R2) reach a preset number of revolutions or fraction of a revolution, for example. The consequent tearing action is rapid and accurate. The checking of the number of revolutions of the cutting rollers (R2) may be operated by means of a counter device (100) mounted on the axis of one of the same rollers (R2) in a manner known per se.

As shown in FIG. 7, the activation of said solenoid valves (70) can be automated by means of a programmable electronic unit (UE) which, via the cables (700), sends electrical signals for the activation, respectively, the deactivation of the solenoid valves (70) in response to electrical signals coming from the control device (100) such as an encoder, for example. The unit (UE) is of a type known to those skilled in the industrial automation field and, therefore, will not be described in greater detail.

As above mentioned, before delivering the air flow through the nozzles (7), the roller (R4) may be accelerated in order to stretch the web (2) in the region interested by the action of the nozzles (7).

Advantageously, as illustrated in FIGS. 5A and 5B of the attached drawings, the nozzles (7) located inside the roller (RA) can be oriented radially to the roller (RA).

Alternatively, as illustrated in FIGS. 2, 4 and 6A-6D of the attached drawings, the nozzles (7) can be positioned externally to the roller (RA), oriented and directed toward a region between the roller (RA) and the logs (R0)-forming station wherein the winding rollers (R4, R5) are made to operate.

To this end, the roller (RA) may be shaped in such a way as to exhibit a plurality of circumferential grooves (76) wherein the extended and correspondingly curved bodies of the nozzles (7) are positioned, the latter being associated with the reservoir (71) located outside and above the roller (RA). In this example, the roller (RA) has the two ends of the shaft (8) supported by stationary parts (80) of the machine with the interposition of corresponding bearings (81), two head flanges (87) corresponding to said stationary parts solid to both sides of the reservoir (71).

The operation of the device according to the above illustrated example is identical to that previously described.

An operating method according to the invention comprises, therefore, a step for feeding a continuous paper web (2) to a station in which the formation of a log (RO) takes place, the web (2) being provided with transverse pre-cutting or perforations at regular intervals, and implies interrupting the continuity of the web at a predetermined moment by means of a jet of fluid such as compressed air, for example, directed toward a perforation or pre-cutting line (p) of the web (2).

According to the present method, the step for the delivery of a jet of fluid may be operated subsequently to a step for the acceleration of roller (R4) which acts on logs (RO) at a log-forming station.

While specific embodiments of the invention have been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles.

Claims

1. An apparatus for causing paper webs to tear off within rewinding machines, the web being provided at regular intervals with transverse perforation lines which subdivide the web into sheets joined to each other but able to be separated in correspondence of the perforation lines, the apparatus comprising: a web-feeding and winding roller comprising a plurality of circumferential grooves, said web-feeding and winding roller winding the web onto at least one log, said web-feeding and winding roller moving the web along at least a portion of a path of the web;a pneumatic means for tearing the web upon passage of a perforation line which separates a last sheet of a log being formed from a first sheet of a next log to be formed, said pneumatic means comprising a reservoir of compressed air and a plurality of nozzles associated with a plurality of solenoid valves, one or more of said plurality of nozzles comprising an extended and curved body portion, said pneumatic means producing a jet of compressed air in a direction of said perforation line via said reservoir of compressed air, one or more of said solenoid valves and one or more of said plurality of nozzles, said plurality of nozzles, said solenoid valves and said reservoir of compressed air being located at a position external to said web-feeding and winding roller; wherein at least a portion of one or more of said circumferential grooves receives said extended and curved body portion of one of said nozzles, said extended and curved body portion extending in a circumferential direction of said web-feeding and winding roller; wherein a groove depth of at least one of said plurality of circumferential grooves is substantially the same as a nozzle thickness of at least one of said nozzles;an underlying roller, said underlying roller and said web-feeding and winding roller defining a channel delimiting a path followed by cores on each of which a predetermined number of said sheets are wound in cooperation with said web-feeding and winding roller, said channel being provided below the web-feeding and winding roller, said jet of compressed air being directed downward towards the channel;an exit roller, said apparatus being configured to hold a first wound log in a first position in contact with the web-feeding and winding roller, the underlying roller and the exit roller and at the same time hold an unwound core in a second position in contact with the web-feeding and winding roller and the underlying roller, said plurality of nozzles having ends positioned and controlled to emit said jets of air between said first wound log in said first position and said unwound core in said second position.

2. An apparatus in accordance with claim 1, wherein said one or more of said plurality of nozzles extends from a position located at a spaced location from said web-feeding and winding roller to a position located within one of said circumferential grooves, said extended and curved body portion being adjacent to an outer surface of said web-feeding and winding roller, said extended and curved body portion of said one or more of said plurality of nozzles extending in said one of said circumferential grooves along an outer circumferential length of said web-feeding and winding roller, said channel extending along a circumferential portion of said web-feeding and winding roller.

3. An apparatus in accordance with claim 1, wherein each of said nozzles has a nozzle width, each of said plurality of circumferential grooves having a circumferential groove width, said circumferential groove width being equal to or greater than said nozzle width.

4. An apparatus in accordance with claim 1, wherein said groove depth of each of said plurality of circumferential grooves is substantially the same as said nozzle thickness of one of said nozzles.

5. An apparatus in accordance with claim 1, wherein said extended and curved body portion is arranged in said at least said portion of said one or more of said circumferential grooves and said extended and curved body portion extends in said at least said portion of said one or more of said circumferential grooves in said circumferential direction of said web-feeding and winding roller.

6. An apparatus in accordance with claim 1, wherein said one or more of said solenoid valves and at least one of said plurality of nozzles define a compressed air flow path, said jet of compressed air moving in said direction of said perforation line via said compressed air flow path, said extended and curved body portion defining a portion of said compressed air flow path, wherein said compressed air flow path is external to an outer periphery of said web-feeding and winding roller.

7. An apparatus in accordance with claim 1, wherein said web-feeding and winding roller is located at a spaced location from said plurality of solenoid valves.

8. An apparatus in accordance with claim 1, wherein said extended and curved body portion comprises an extended and curved body portion contour, said at least said portion of one or more of said circumferential grooves comprising a circumferential groove portion contour, said circumferential groove portion contour being substantially the same as said extended and curved body portion contour.

9. An apparatus for causing paper webs to tear off within rewinding machines, the apparatus comprising: a rewinding machine including a web-feeding and winding roller having a tubular jacket outer surface, said tubular jacket outer surface defining a plurality of grooves, each of said plurality of grooves extending in a circumferential direction of said roller;a web having a plurality of transverse perforation lines, one perforation line and another perforation line defining a sheet, said plurality of transverse perforation lines including a selected perforation line, said selected perforation line defining a last sheet of a log being formed and a first sheet of a next log to be formed, said web-feeding and winding roller winding said web onto at least one said log, said web-feeding and winding roller moving said web along at a least portion of a path of said web;a reservoir of compressed air;a plurality of solenoid valves; a plurality of nozzles associated with said plurality of solenoid valves, said plurality of nozzles, said reservoir of compressed air and said plurality of solenoid valves producing a jet of compressed air in a direction of said selected perforation line, each of said plurality of nozzles comprising a curved portion, said nozzles and said solenoid valves being positioned at a location outside of said web-feeding and winding roller, at least a portion of said curved portion of each of said nozzles being arranged in at least a portion of one of said circumferential grooves, wherein a groove depth of said circumferential grooves is substantially equal to a thickness of at least one of said nozzles, said curved portion defining a portion of a fluid flow path of said compressed air, wherein said compressed air is guided along said portion of said fluid flow path in said circumferential direction of said roller via said curved portion,said rewinding machine further comprising an underlying roller, said underlying roller and said web-feeding and winding roller defining a channel delimiting a path followed by cores on each of which a predetermined number of said sheets are wound in cooperation with said web-feeding and winding roller, said channel being provided below the web-feeding and winding roller, said jet of compressed air being directed downwards towards the channel;an exit roller, said apparatus being configured to hold a first wound log in a first position in contact with the web-feeding and winding roller, the underlying roller and the exit roller and at the same time hold an unwound core in a second position in contact with the web-feeding and winding roller and the underlying roller, said plurality of nozzles having ends positioned and controlled to emit said jets of air between said first wound log in said first position and said unwound core in said second position.

10. An apparatus in accordance with claim 9, wherein at least one of said solenoid valves and said at least one of said nozzles define a compressed air flow path, said curved portion of each of said nozzles extending within said one of said one of said circumferential grooves along a circumferential length of said tubular jacket outer surface.

11. An apparatus in accordance with claim 9, wherein each of said nozzles has a nozzle width, each of said plurality of circumferential grooves having a circumferential groove width, said circumferential groove width being equal to or greater than said nozzle width.

12. An apparatus in accordance with claim 9, wherein said thickness of each of said nozzles is substantially equal to said groove depth of one of said plurality of circumferential grooves.

13. An apparatus in accordance with claim 9, wherein said at least said portion of said curved portion extends in said at least said portion of one of said circumferential grooves in said circumferential direction of said web-feeding and winding roller.

14. An apparatus in accordance with claim 9, wherein said at least said portion of said curved portion has a contour that is substantially the same as a contour of said least said portion of one of said circumferential grooves.

15. An apparatus for causing paper webs to tear off within rewinding machines, the apparatus comprising: a rewinding machine including a web-feeding and winding roller having a tubular jacket outer surface, said tubular jacket outer surface defining a plurality of grooves, each of said plurality of grooves extending in a circumferential direction of said roller, one or more of said plurality of grooves having a groove depth;a reservoir of compressed air;a solenoid valve;a nozzle associated with said solenoid valve, said nozzle having a nozzle thickness, said nozzle thickness being substantially equal to said groove depth, said nozzle, said reservoir of compressed air and said solenoid valve producing a jet of compressed air, said nozzle comprising a curved nozzle portion, said solenoid valve and at least a portion of said curved nozzle portion being positioned at a location outside of said web-feeding and winding roller, at least another portion of said curved nozzle portion being arranged in at least a portion of one of said circumferential grooves and said at least another portion of said curved nozzle portion extending along a circumferential portion of said web-feeding and winding roller in said at least said portion of one of said circumferential grooves in said circumferential direction of said one of said circumferential grooves, said circumferential portion comprising a circumferential portion surface facing in a direction of said at least another portion of said curved nozzle portion, said circumferential portion surface comprising a circumferential portion contour, said at least another portion of said curved nozzle portion having a curved nozzle portion surface facing in a direction of said circumferential portion, said curved nozzle portion surface having a curved nozzle portion surface contour, wherein said curved nozzle portion surface contour corresponds to said circumferential portion contour, said curved nozzle portion defining a portion of a fluid flow path of said compressed air, wherein said compressed air flows along said portion of said fluid flow path in said circumferential direction of said web-feeding and winding roller;said rewinding machine further comprising an underlying roller, said underlying roller and said web-feeding and winding roller defining a channel delimiting a path followed by cores on each of which a predetermined number of said sheets are wound in cooperation with said web-feeding and winding roller, said channel being provided below the web-feeding and winding roller, said jet of compressed air being directed downwards towards the channel;an exit rover, said apparatus being configured to hold a first wound log in a first position in contact with the we-feeding and winding roller, the underlying roller and the exit roller and at the same time hold an unwound core in a second position in contact with the web-feeding and winding roller and the underlying roller, said plurality of nozzles having ends positioned and controlled to emit said jets of air between said first would log in said first position and said unwound core in said second position.