Method and Apparatus for Tail Sealing of Roll Products

Description

RELATED APPLICATION DATA

This application claims priority benefit to U.S. provisional application Ser. No. 63/650,116, filed May 21, 2024, the disclosure of which is incorporated by reference herein.

BACKGROUND

This disclosure is directed to methods and apparatus for producing roll products such as bathroom tissue, kitchen towel (also called household towel), hardwound towel, industrial products, and canister wipes. In particular, the disclosure is directed toward attaching the end of the convolutely wound web at the outside of the roll product to the next layer of web underneath the end of the web, which is known in the industry as sealing the tail of the web. More particularly, this disclosure is directed toward an improved method and apparatus for determining the circumferential position of the tail end on the roll to facilitate such sealing.

It is well known in the art that rolls or logs of convolutely wound paper are typically formed on a machine known as a rewinder line, also known as a converting line. A rewinder line is used to convert large parent rolls of paper into smaller sized rolls of bathroom tissue, kitchen towel, hardwound towel, industrial products, and the like. A rewinder line usually comprises one or more unwinds, modules for paper finishing (e.g., embossing, laminating, printing, perforating), a rewinder for winding the paper into an elongated roll, commonly referred to as a log, and a tail sealing unit. The rewinder line may also include a mandrel extractor for withdrawing winding mandrels to make coreless logs. Typically, the rewinder produces logs which are about 90 to 203 mm in diameter for bathroom tissue and kitchen towel and about 100 to 350 mm in diameter for hardwound towel and industrial products. Log length is usually about 1.5 to 5.4 m, depending on the width of the parent roll. The logs are subsequently cut transversely to obtain small rolls about 90 to 115 mm long for bathroom tissue and about 200 to 300 mm long for kitchen towel and hardwound towel.

The tail end of the web at the outside surface of the log is sealed for production and consumer purposes. From a production standpoint, having the tail sealed prevents disruptions to the downstream process such as cutting and packaging due to loose web from unwinding logs. From a consumer standpoint, having the tail sealed prevents rolls being unwound until desired by the consumer. The tail may be sealed with one or more of adhesive, water, ultrasonic bonding, embossing, mechanical knurling, needle punching, and heat. When adhesive or water is used, the adhesive or water may be applied to the web or to the next layer of web underneath the tail end.

A tail sealing machine, or tail sealer, tail seal unit or tailseal, is generally defined as a machine that attaches the end of convolutely wound web at the outside of a roll product to the next layer of web underneath the end of the web. When the tail sealing process requires an adhesive to be applied between the tail end of the web and the next layer of web underneath, the end position of the tail on the outer surface or circumference of the log must first be determined. The prior art discloses various approaches to determining the end position of the tail.

U.S. Pat. No. 4,475,974 discloses “The rotation of the two rollers causes the rotation of the stick 44 in the direction of the arrow f44 i.e. in a clockwise direction. During this rotation the air blown by the nozzles 133 causes the edge 44L of the stick to open and the said edge rests on the plate 83. A sensor S (such as a photocell or the like), which is intercepted by the edge 44L, provides a signal which causes the motor 89 to stop immediately and therefore to stop also the rotation of the roller 95 when the latter is in the correct desired position.”

U.S. Pat. No. 4,963,223 discloses “In the position shown in FIG. 1, the device 7 is momentarily at a standstill, while the rollers 11,11 rotate in the direction f11 by means of actuating members described in detail below. At the same time, the air stream of the nozzles 15,17 causes unwinding of the free portion L2 of the reel B2 located on the rollers 11,11. Simultaneous rotation of the reel B2, performed by the rollers 11,11 on which it rests, causes the free portion L2, partially unwound, to be positioned on the surface 25 of a suction box 27 supported by a carrying structure 27X. The surface 25 is provided with suction openings 26 communicating with the inside of the suction box 27. Since a vacuum exists inside the box 27 during this phase, the portion L2 adheres to the surface 25. It is also possible to provide as an alternative a blowing action using a nozzle which is able to follow the portion along its path between the two stations, retracting during its return travel. Rotation of the rollers 11,11 continues until the edge of the portion L2 reaches a given position with respect to the surface 25, reaching of this position being detected by a sensor 31 arranged in a suitable position with respect to the device 7.”

U.S. Pat. No. 5,242,525 discloses “The disks 33 are intended to rotate in counter-clockwise direction as indicated by arrow f33 in FIG. 3. The group 31 for the unwinding of the tail L of incoming logs further includes blow nozzles which include an upper set of nozzles 35 arranged between sections of the upper conveyor belt 15 and located in grooves of the roller 25. An additional set of nozzles may be used, as shown in FIGS. 6 and 7 and indicated by 37. An optical sensor, including at least a photoelectric cell 39, (FIGS. 3 and 7) is designed to detect the end of the unwound tail and makes part of the group 31 as well.”

U.S. Pat. No. 6,143,111 discloses “Meanwhile the vacuum space 9 is in depression because of the suction exerted by the vacuum box 151. Consequently, when the tall end LF appears on the right hand side (in FIG. 2) of the reel L, it is detached from the external surface of the reel L, unwound from it and sucked into the vacuum space 9. FIG. 2 shows the tail end LF as it first comes away from the external surface of the reel L while FIG. 1 shows the position assumed by the tail end LF once sucked into the vacuum space 9. The roll 7 continues to rotate even when the tail end LF is inside the vacuum space 9 and therefore said end is gradually drawn out and rewound onto the reel L until the terminal edge of the tail end LF is in front of a sensor, which may be optical or the like.”

U.S. Pat. No. 5,679,206 discloses “The nozzles 32 direct a blast of air toward the unsealed roll 18 of material, as shown in FIG. 5, to loosen (unroll) a tail 38 or free end from the roll 18, so that the tail 38 falls toward a tail support 40. Thereafter, the blast of air from the nozzles 32 automatically terminates, as described below. In accordance with the invention, the apparatus may include a sensor for detecting a tail at the tail supporting surface. As embodied herein and shown in FIG. 1, a tail sensor 56 is positioned beneath a hole 58 in the tail support 40 to detect when a tail 38 is present at the tail supporting surface 42. The tail sensor 56 is preferably a retroflective bifurcated fiber optic sensor or photoeye for detecting when the tail 38 covers the hole 58, however this element may be any detector capable of sensing the presence of the tail 38.”

U.S. Pat. No. 5,800,652 discloses “In the first embodiment, tail detection makes use of an ink marker (prelocated during the winding operation) on the tail of the log” and “In FIG. 22, the upper roller 43 is rotating counterclockwise as indicated by the arrow 43a and the lower vacuum-equipped roller 44 is rotating counterclockwise as is designated by the arrow 44b. This corresponds generally to the showings in FIGS. 6-8 of the first embodiment. The air blast continues through the showings in FIGS. 24-26 to blow the tail down onto the table 57 as seen in FIG. 26 and where it is in the process of being sensed by a photo electric eye 47.”

U.S. Pat. No. 9,675,216 discloses “A blow pipe 20 emits a burst of air, causing the tail 22 to separate from the body 13 of the log 12 and move towards a table 24. As the turn rollers 18 continue to rotate the log 12, the tail 22 moves within range of the tail detection mechanism 26 (e.g., a photo eye sensor) and rests on or near the table 24.”

U.S. Pat. No. 11,305,957 discloses “The generation of a flow of air by the first Coanda effect nozzle 23 positioned in the inlet 19 of the aperture 21 causes the tail end LF to enter said aperture 21, as shown in FIG. 4A, where the tail end LF is shown in three distinct positions that show the movement of the tail end LF under the effect of the air currents generated by the nozzles 51 and by the Coanda effect nozzle 23. Once the tail end LF has been inserted into the aperture 21, the directions of the movement of the peripheral contact roller 15 and of the flexible member 3 are reversed, as shown by the arrows in FIG. 4B. Consequently, the log R starts to turn in the unwinding direction and, as a result of the air current generated by the first Coanda effect nozzle 23, the tail end LF is pulled into the aperture 21 passing in front of a photocell 53 or other detection member. Unwinding of the log R continues until, based on the signal generated by the photocell 53 and on the angular movement of the peripheral contact roller 15 and/or of the linear movement of the flexible member 3 (which can be detected by an encoder), a suitable length of web material N forming the log R has been unwound inside the aperture 21.”

A common thread in the aforementioned prior art is that in order to determine the tail end's circumferential position on the roll, the tail of the web at the outside of the log is opened with a blast of air or with a vacuum. Prior art methods consume energy (increasing operating costs), require setup time and adjustment (reducing availability), consume processing time (reducing production rates), and introduce opportunities for process upsets (reducing reliability). The drawbacks of the prior art are addressed in the description that follows below.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevation of an exemplary tail sealing machine.

FIG. 2 is a schematic diagram of a conventional means of locating a position of an end of a tail or a log of convolutely wound web material.

FIG. 3 is a schematic diagram of an exemplary system for locating a position of an end of a tail or a log of convolutely wound web material in accordance with the disclosure.

FIG. 4 is a detail view of an implementation in accordance with the disclosure in the tail sealing machine of FIG. 1.

FIG. 5 is a graph of detection data representative of the end position of the tail collected from an implementation in accordance with the disclosure.

DETAILED DESCRIPTION

A common embodiment of a tail sealing machine 10 is illustrated in FIG. 1. An incoming log 12 comes from the rewinder 14, either via a conveyor from the rewinder or down an infeed table 16, and is slowed by a log brush 18. A loader 20 indexes the log 12 into the tail seal machine 10. The preparation rollers 22 detect the tail and prepare it for unwinding and sealing. The unwinding rollers 24 spin the log 12 so the tail is unwound for adhesive application. The adhesive cable 26 applies a line of adhesive to seal the tail to the log 12. The tail pressing roll 28 presses the tail into the adhesive line on the log. The tail position roll 30 controls the position of the tail as it is ejected from the tail seal machine. The outfeed table 32 feeds the log 12 into the next module 34. The preparation rollers 22 as well as other components of the tail sealing machine 10 are supported by a framework which may form lateral sides of the machine.

The preparation rollers 22 generally position the log 12 so the tail 36 is in the correct place for the next step. Photo eyes detect when the log reaches the center line between the preparation rollers. At that point, the preparation rollers 22 match speed to hold the log stationary within the nip between the preparation rollers 22. As the log 12 is rotated in the nip between the preparation rollers 22, a sensor detects the tail 36.

FIG. 2 schematically illustrates the current state of the art in locating the end position of the tail 36 of the log 12. In this common embodiment, the log 12 is rotated in a stationary position in the nip between the preparation rollers 22 and an air blast 38 from a high pressure air source 40 opens the tail 36 (i.e. separates the tail from the body of the log) such that the tail covers a sensor 42. Then as the tail 36 is rewound onto the log 12 with the preparation rollers, the point at which the sensor 42 is no longer covered by the tail 36 indicates that the end of the tail has passed by the sensor. Given the diameter of the log 12 and the position of the sensor 42 relative to the location where the log is rotated in the nip between the preparation rollers, which may be determined by the photo eyes, the circumferential position of the end of the tail 36 on the log 12 can be determined. In subsequent processing, the tail 36 is opened a second time so that adhesive can be applied to the log 12 or to the tail 36.

FIG. 3 schematically illustrates locating the position of the end of the tail 36 of the log 12 in accordance with the disclosure. The circumferential position of the end of the tail 36 on the log 12 is determined utilizing a sensor 44 such as a distance sensor which may be a laser gauging sensor (for example, a high precision laser measuring sensor such as Banner Engineering model LM80KIQP) to look directly at the log body. The distance sensor may generate a signal representative of the distance from the sensor to the log 12 at a plurality of times as the log is rotated in the nip between the preparation rollers 22. The sensor 44 may also in effect sense the diameter of the log 12 at a plurality of times as the log is rotated in the nip between the preparation rollers based on the distance between the sensor 44 and the surface of the log 12. Other sensors for measuring diameter and web caliper may also be used to establish the distance between the sensor and the surface of the log or to capture log diameter.

The tail seal machine 10 may be provided with a controller 50 in communication with the sensor 44. The controller 50 may be adapted and configured for controlling the tail seal machine 10 or may integrated into a controller for controlling additional machines on the converting line. The controller 50 may include a processor 52 and memory 54. The controller may be adapted and configured to: (i) process a plurality of signals from the sensor 44 at a plurality of times during rotation of the log 12 between the preparation rollers 22, (ii) detect a change in the plurality of signals from the sensor at the plurality of times during rotation of the log between the preparation rollers 22, (iii) associate the change in the signals with the circumferential location of the end of the tail 36 of the log 12, and (iv) store a plurality of data structures 56 in the memory 54 of the controller 50. The data structures 56 may comprise a plurality of data items associated together that are representative of the circumferential location of the end of the tail 36 of the log 12. The sensor 44 may be in communication with the controller 50 and may be configured to sense a distance from the sensor to the log 12 or the diameter of the log 12 at a plurality of times while rotating the log in the stationary position between the preparation rollers 22, and generate a plurality of signals corresponding to the diameter of the log 12 at the plurality of times that are to be transmitted to the controller 50. The controller 50 may be configured to compare the signals corresponding to the distance of the sensor from the log or the diameter of the log 12 at the plurality of times and detect a change in the signals corresponding to the diameter of the log at the plurality of times. The controller 50 may be configured to associate the change in the signals with the circumferential location of the end of the tail 36 of the log 12.

A rapid change in the signals from the sensor 44 indicates the position of the end of the tail 36 on the outer surface or circumference of the log 12. The signal from the sensor 44 may be processed, for example, by using a Savitzky-Golay filter to generate a smoothed derivative representation of the signal. The controller 50 may associate a change in signal representative of the distance from the sensor to the log or the log diameter with the end position of the tail 36 on the outer surface or circumference of the log. Given that the log diameter is known, and assuming traction (no slip) between the log and machine members (e.g., the preparation rollers), the circumferential location of the tail end can be tracked during subsequent processing. The method may be augmented by using a low volume air 58 from a pressurized air source 60 to help to lift the tail 36 off of the log body. The pressurized air 58 from the air source 60 could be directed in either direction relative to the log's winding direction: directly toward the tail end (in a direction that would tend to open the tail), or indirectly over the tail end (opposite the direction that would tend to open the tail) to leverage the Coanda effect.

In tail sealing machines 10 such as shown in FIG. 1, the tail location function takes place on a first set of driven rollers (for example, preparation rollers 22) while the function of opening the tail so that adhesive can be applied takes place on a second set of rollers (for example, unwinding rollers 24). In such tail sealing machines 10, the sensor 44 may be mounted on the movable carriage for the upper preparation roller. The moveable carriage allows the upper preparation roller 22 to move relative to the lower preparation roller 22 which remains fixed in position relative to the frame 35, such that the space between the rollers may be changed based on log diameter.

The log may roll and be received into the preparation rollers 22. The preparation rollers 22 rotate at different speeds to draw the log 12 into the nip between the rollers 22. Photo eyes detect when the log reaches the centerline between the preparation rollers 22, and at that point the rollers 22 match speed to rotate the log 12 in a stationary position such that the end of the tail 36 passes the measuring point of the sensor 44 within one revolution of the log 12. The rapid change in the signal from the sensor 44 may be caused by one or any combination of: the thickness or caliper of the web at the end of the tail 36, the tail having moved away from the log body due to centrifugal reaction to log's rotation, the tail having moved away from the log body caused by a direct or indirect air stream 58.

FIG. 5 is a chart of data collected from the sensor 44 for several subsequent logs. After the circumferential location of the tail end of the log has been determined, the rolls 22 may continue to rotate (or alternatively, to reverse rotational direction) in order to position the tail end in a desirable orientation for subsequent processing. When the tail end is in a satisfactory orientation, the log may be fed to the next step in the tail sealing process, for example, unwinding rollers 24. In subsequent processing, the tail may be opened so that adhesive can be applied to the log or to the tail.

In an alternate embodiment in tail sealing machines where the tail end location function takes place on the same set of rolls as the tail opening function, the sensor 44 may be mounted on the movable carriage of the upper roll. In another alternate embodiment of log rotation for tail end detection, the log may be rotated by driven members that engage the inside diameter of each end of the core; these driven members may be similar to center drives in a rewinding machine, for instance, as described in U.S. Pat. No. 11,247,863. In another alternate embodiment of log rotation for tail end detection, the log may be rotated by two rollers located beneath the log, in an arrangement similar to a two-drum rewinder.

The arrangement described herein provides benefits to the process of determining the circumferential location of the tail end of a roll in terms of operating cost, setup and adjustment time, production speed, and reliability. The arrangement described herein eliminates the energy required to generate a vacuum or an air blast to open the tail of the log in order to locate the tail end, with potentially only low volume air or no compressed air required, providing for a reduced operating cost. The arrangement described herein reduces setup and adjustment time by eliminating the need to change the angle of an air blast for log diameter, or to change air pressure settings for different paper grades and/or roll product configurations. The arrangement described herein increases production speed by eliminating the time consumed in the opening the tail of the log in order to locate the tail end. The arrangement described herein increases reliability by eliminating the process upsets that inevitably occur with even robust tail opening systems.

Further embodiments can be envisioned by one of ordinary skill in the art after reading this disclosure. In other embodiments, combinations or sub-combinations of the above-disclosed invention can be advantageously made. The example arrangements of components are shown for purposes of illustration and it should be understood that combinations, additions, re-arrangements, and the like are contemplated in alternative embodiments of the present invention. Thus, various modifications and changes may be made thereunto without departing from the broader spirit and scope of the invention as set forth in the claims and that the invention is intended to cover all modifications and equivalents within the scope of the following claims.