Method and Apparatus for Tail Sealing of Roll Products

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.

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 stickin the direction of the arrow fi.e. in a clockwise direction. During this rotation the air blown by the nozzlescauses the edgeL of the stick to open and the said edge rests on the plate. A sensor S (such as a photocell or the like), which is intercepted by the edgeL, provides a signal which causes the motorto stop immediately and therefore to stop also the rotation of the rollerwhen the latter is in the correct desired position.”

U.S. Pat. No. 4,963,223 discloses “In the position shown in, the deviceis momentarily at a standstill, while the rollers,rotate in the direction fby means of actuating members described in detail below. At the same time, the air stream of the nozzles,causes unwinding of the free portion Lof the reel Blocated on the rollers,. Simultaneous rotation of the reel B, performed by the rollers,on which it rests, causes the free portion L, partially unwound, to be positioned on the surfaceof a suction boxsupported by a carrying structureX. The surfaceis provided with suction openingscommunicating with the inside of the suction box. Since a vacuum exists inside the boxduring this phase, the portion Ladheres to the surface. 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,continues until the edge of the portion Lreaches a given position with respect to the surface, reaching of this position being detected by a sensorarranged in a suitable position with respect to the device.”

U.S. Pat. No. 5,242,525 discloses “The disksare intended to rotate in counter-clockwise direction as indicated by arrow fin. The groupfor the unwinding of the tail L of incoming logs further includes blow nozzles which include an upper set of nozzlesarranged between sections of the upper conveyor beltand located in grooves of the roller. An additional set of nozzles may be used, as shown inand indicated by. An optical sensor, including at least a photoelectric cell, () is designed to detect the end of the unwound tail and makes part of the groupas well.”

U.S. Pat. No. 6,143,111 discloses “Meanwhile the vacuum spaceis in depression because of the suction exerted by the vacuum box. Consequently, when the tall end LF appears on the right hand side (in) of the reel L, it is detached from the external surface of the reel L, unwound from it and sucked into the vacuum space.shows the tail end LF as it first comes away from the external surface of the reel L whileshows the position assumed by the tail end LF once sucked into the vacuum space. The rollcontinues to rotate even when the tail end LF is inside the vacuum spaceand 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 nozzlesdirect a blast of air toward the unsealed rollof material, as shown in, to loosen (unroll) a tailor free end from the roll, so that the tailfalls toward a tail support. Thereafter, the blast of air from the nozzlesautomatically 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, a tail sensoris positioned beneath a holein the tail supportto detect when a tailis present at the tail supporting surface. The tail sensoris preferably a retroflective bifurcated fiber optic sensor or photoeye for detecting when the tailcovers the hole, however this element may be any detector capable of sensing the presence of the tail.”

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, the upper rolleris rotating counterclockwise as indicated by the arrowand the lower vacuum-equipped rolleris rotating counterclockwise as is designated by the arrow. This corresponds generally to the showings inof the first embodiment. The air blast continues through the showings into blow the tail down onto the tableas seen inand where it is in the process of being sensed by a photo electric eye.”

U.S. Pat. No. 9,675,216 discloses “A blow pipeemits a burst of air, causing the tailto separate from the bodyof the logand move towards a table. As the turn rollerscontinue to rotate the log, the tailmoves within range of the tail detection mechanism(e.g., a photo eye sensor) and rests on or near the table.”

U.S. Pat. No. 11,305,957 discloses “The generation of a flow of air by the first Coanda effect nozzlepositioned in the inletof the aperturecauses the tail end LF to enter said aperture, as shown in, 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 nozzlesand by the Coanda effect nozzle. Once the tail end LF has been inserted into the aperture, the directions of the movement of the peripheral contact rollerand of the flexible memberare reversed, as shown by the arrows in. 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, the tail end LF is pulled into the aperturepassing in front of a photocellor other detection member. Unwinding of the log R continues until, based on the signal generated by the photocelland on the angular movement of the peripheral contact rollerand/or of the linear movement of the flexible member(which can be detected by an encoder), a suitable length of web material N forming the log R has been unwound inside the aperture.”

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.

A common embodiment of a tail sealing machineis illustrated in. An incoming logcomes from the rewinder, either via a conveyor from the rewinder or down an infeed table, and is slowed by a log brush. A loaderindexes the loginto the tail seal machine. The preparation rollersdetect the tail and prepare it for unwinding and sealing. The unwinding rollersspin the logso the tail is unwound for adhesive application. The adhesive cableapplies a line of adhesive to seal the tail to the log. The tail pressing rollpresses the tail into the adhesive line on the log. The tail position rollcontrols the position of the tail as it is ejected from the tail seal machine. The outfeed tablefeeds the loginto the next module. The preparation rollersas well as other components of the tail sealing machineare supported by a framework which may form lateral sides of the machine.

The preparation rollersgenerally position the logso the tailis 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 rollersmatch speed to hold the log stationary within the nip between the preparation rollers. As the logis rotated in the nip between the preparation rollers, a sensor detects the tail.

schematically illustrates the current state of the art in locating the end position of the tailof the log. In this common embodiment, the logis rotated in a stationary position in the nip between the preparation rollersand an air blastfrom a high pressure air sourceopens the tail(i.e. separates the tail from the body of the log) such that the tail covers a sensor. Then as the tailis rewound onto the logwith the preparation rollers, the point at which the sensoris no longer covered by the tailindicates that the end of the tail has passed by the sensor. Given the diameter of the logand the position of the sensorrelative 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 tailon the logcan be determined. In subsequent processing, the tailis opened a second time so that adhesive can be applied to the logor to the tail.

schematically illustrates locating the position of the end of the tailof the login accordance with the disclosure. The circumferential position of the end of the tailon the logis determined utilizing a sensorsuch 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 logat a plurality of times as the log is rotated in the nip between the preparation rollers. The sensormay also in effect sense the diameter of the logat a plurality of times as the log is rotated in the nip between the preparation rollers based on the distance between the sensorand the surface of the log. 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 machinemay be provided with a controllerin communication with the sensor. The controllermay be adapted and configured for controlling the tail seal machineor may integrated into a controller for controlling additional machines on the converting line. The controllermay include a processorand memory. The controller may be adapted and configured to: (i) process a plurality of signals from the sensorat a plurality of times during rotation of the logbetween the preparation rollers, (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, (iii) associate the change in the signals with the circumferential location of the end of the tailof the log, and (iv) store a plurality of data structuresin the memoryof the controller. The data structuresmay comprise a plurality of data items associated together that are representative of the circumferential location of the end of the tailof the log. The sensormay be in communication with the controllerand may be configured to sense a distance from the sensor to the logor the diameter of the logat a plurality of times while rotating the log in the stationary position between the preparation rollers, and generate a plurality of signals corresponding to the diameter of the logat the plurality of times that are to be transmitted to the controller. The controllermay be configured to compare the signals corresponding to the distance of the sensor from the log or the diameter of the logat the plurality of times and detect a change in the signals corresponding to the diameter of the log at the plurality of times. The controllermay be configured to associate the change in the signals with the circumferential location of the end of the tailof the log.

A rapid change in the signals from the sensorindicates the position of the end of the tailon the outer surface or circumference of the log. The signal from the sensormay be processed, for example, by using a Savitzky-Golay filter to generate a smoothed derivative representation of the signal. The controllermay 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 tailon 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 airfrom a pressurized air sourceto help to lift the tailoff of the log body. The pressurized airfrom the air sourcecould 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 machinessuch as shown in, the tail location function takes place on a first set of driven rollers (for example, preparation rollers) 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). In such tail sealing machines, the sensormay be mounted on the movable carriage for the upper preparation roller. The moveable carriage allows the upper preparation rollerto move relative to the lower preparation rollerwhich remains fixed in position relative to the frame, 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. The preparation rollersrotate at different speeds to draw the loginto the nip between the rollers. Photo eyes detect when the log reaches the centerline between the preparation rollers, and at that point the rollersmatch speed to rotate the login a stationary position such that the end of the tailpasses the measuring point of the sensorwithin one revolution of the log. The rapid change in the signal from the sensormay be caused by one or any combination of: the thickness or caliper of the web at the end of the tail, 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.

is a chart of data collected from the sensorfor several subsequent logs. After the circumferential location of the tail end of the log has been determined, the rollsmay 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. 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 sensormay 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.