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, said web-feeding and winding roller rotating at a first speed such that said web is in a non-stretched state, said web-feeding and winding roller rotating at a second speed such that a portion of said web in an area of a selected perforation line of said web is in a stretched state against said web-feeding and winding roller, said first speed being less than said second speed;a pneumatic means for tearing the web upon passage of the selected 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, said pneumatic means producing a jet of compressed air in a direction of said selected 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 an extended and curved body portion of one of said nozzles, said one or more of said circumferential grooves having a curved groove orientation, said curved body portion having a curved body orientation, said curved body orientation substantially corresponding to said curved groove orientation, said web-feeding and winding roller rotating at said second speed such that said portion of said web in said area of said selected perforation line is in said stretched state when said selected perforation line is separated via said jet of compressed air,said one or more of said circumferential grooves having a minimal depth such that the outer surface of the curved body portion of one of said nozzles is substantially aligned with an outer surface of said web-feeding and winding roller and immediately adjacent to the web to tear the web when in its stretched state.

2. An apparatus in accordance with claim 1, wherein said extended and curved body portion extends in a circumferential direction of said web-feeding and winding roller.

3. An apparatus in accordance with claim 1, further comprising: a first core;a second core, said 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 said selected perforation line, said selected perforation line defining said last sheet applied to said first core and said first sheet applied to said second core, said web-feeding and winding roller applying said web to said first core until said first core receives a preset number of sheets, said web-feeding and winding roller being in contact with said second core with said web in said stretched state;a guide element arranged adjacent to said web-feeding and winding roller, said guide element defining at a least a portion of a core moving path, wherein said first core and said second core are movable along said core moving path, said extended and curved body portion comprising an end portion, said end portion facing in a direction of said guide element.

4. An apparatus in accordance with claim 1, wherein said extended and curved body portion is located in said grooves of said web-feeding and winding roller, said outer roller surface defining said circumferential grooves, wherein an outer portion of said web-feeding roller and winding roller is located between each of said nozzles.

5. 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, at least a portion of said air flow path extending in a circumferential direction of said web-feeding and winding roller.

6. 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.

7. An apparatus for causing paper webs to tear off within rewinding machines, the apparatus comprising: a rewinding machine including a winding roller and a web-feeding and winding roller having a tubular jacket outer surface, said tubular jacket outer surface defining a plurality of circumferential grooves, said web-feeding and winding roller having a roller axis;a first core;a second core;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 applied to said first core and a first sheet applied to said second core, said winding roller receiving said web via said web-feeding and winding roller, said winding roller applying said web to said first core until said first core receives a preset number of sheets, said winding roller rotating at a first speed such that said web is in a non-stretched state, said winding roller rotating at a second speed such that a portion of said web in an area of said selected perforation line is in a stretched state, said first speed being less than said second speed;a plurality of solenoid valves;a plurality of nozzles associated with said plurality of solenoid valves, at least one of said plurality of nozzles and at least one of said plurality of solenoid valves producing a jet of compressed air in a direction of said selected perforation line such that said jet of compressed air separates said web at said selected perforation line, said at least one of said plurality of nozzles extending from a position at or adjacent to said at least one of said plurality of solenoid valves to a position at or adjacent to said web-feeding and winding roller to define a compressed air flow path, said at least one of said plurality of nozzles comprising a curved body portion, said curved body portion being arranged in at least a portion of one of said circumferential grooves, at least a portion of said curved body portion extending in a circumferential direction of said web-feeding and winding roller, said at least said portion of said curved body portion comprising a curved body portion concavity on one side thereof, said at least said portion of one of said circumferential grooves comprising a groove concavity, said curved body portion concavity and said groove concavity being oriented in a direction of said roller axis, said winding roller rotating at said second speed such that said portion of said web in said area of said selected perforation line is in said stretched state when said selected perforation line is separated via said jet of compressed air, said plurality of solenoid valves being positioned adjacent to said web-feeding and winding roller, wherein said plurality of solenoid valves are located at a spaced location from said web-feeding and winding roller, said tubular jacket being in contact with said second core and said web in said stretched state,said one or more of said circumferential grooves having a minimal depth such that the outer surface of the curved body portion of one of said nozzles is substantially aligned with an outer surface of said web-feeding and winding roller and immediately adjacent to the web to tear the web when in its stretched state.

8. An apparatus in accordance with claim 7, wherein at least a portion of said flow of said jet of compressed air passes through said curved body portion to define a curved nozzle flow path portion, wherein said jet of compressed air moves in a circumferential direction of said web-feeding and winding roller along said curved nozzle flow path portion, each of said nozzles being separated from another one of said nozzles via a portion of said tubular jacket outer surface.

9. An apparatus in accordance with claim 1, wherein said curved body portion receives a flow of said compressed air, said flow of said compressed air moving in a circumferential direction of said web-feeding and winding roller, said rewinding machine comprising a guide element, said guide element being located opposite each of said nozzles, said guide element being arranged opposite said web-feeding and winding roller, said guide element defining at a least a portion of a core moving path, wherein said first core and said second core are movable along said core moving path.

10. An apparatus in accordance with claim 7, wherein said curved body portion defines at least a portion of said compressed air flow path, wherein said compressed air moves along said curved body portion in said circumferential direction of said web-feeding and winding roller.