Rewinder mandrel system for winding paper

A rewinder mandrel system for winding paper into rolls on a mandrel that includes a turret assembly having at least one mandrel affixed thereto. The rewinder mandrel system can also include a gas circulation system that can aid in the positioning, loading, and removing of paper or paper cores located on the mandrel. In particular, the gas circulation system can contain one or more gas flow control devices configured to provide positive pressure and a suction force. In one embodiment, a gas flow control device rotatably affixed to the turret interacts with a second stationary gas flow control device to provide air circulation to the mandrels.

FIELD OF THE INVENTION
 The present invention generally relates to a rewinder system, such as the
 type used to rewind tissues or other paper webs from a supply web onto a
 core. More particularly, the present invention is directed to a rewinder
 system having a number of mandrels that can be indexed by a turret
 assembly. The mandrels can be supplied with vacuum or positive air
 pressure to aid in the winding process.
 BACKGROUND OF THE INVENTION
 Various paper products, such as tissues and other paper webs, are typically
 formed into large supply rolls after being manufactured. In order to
 commercially utilize paper from these supply rolls, it is necessary to
 rewind the paper from the large supply roll onto a smaller sized roll,
 which is generally more useful for commercial purposes. For example, in
 conventional systems, a core is often placed onto a mandrel that is
 capable of spinning so that the spinning of the mandrel in conjunction
 with the core can effectuate winding of the paper thereon.
 Techniques for utilizing mandrels for winding paper are generally well
 known in the art. For example, a turret-style winding system is one
 well-known method used to wind paper onto a core. Most turret systems
 include a number of mandrels that are each capable of spinning
 independently of each other so that multiple paper logs can be formed
 simultaneously. For example, in some conventional turret systems, a core
 is first loaded onto a mandrel. After loading, the mandrel and core can be
 spun so that a sheet of paper can be wound around the core. Once the
 desired amount of paper is wound onto the core, the core and paper can
 then be removed.
 To effectively utilize a turret-style winding system, such as discussed
 above, it is generally necessary to ensure that the core remain securely
 fit onto the mandrel during spinning. If the core moves slightly about the
 mandrel while the paper is being wound, the paper might improperly wind
 onto the core, forming an undesirable asymmetrically wound roll.
 In the past, various techniques were utilized to keep the core in a fixed
 position relative to the mandrel. For example, in some systems,
 mechanically operated dogs that cut into the core were used to maintain
 the position of the core relative to the mandrel. In order to support such
 mechanically operated dog systems, it was typically required that the
 mandrels be made from steel or some other heavy material. However, the use
 of steel and other heavy materials caused the mandrels to rotate and index
 about the turret at slower speeds, and thus, produced fewer paper logs per
 minute. Moreover, these dog systems often caused damage to the cores.
 As such, a need currently exists for an improved system for winding paper
 onto a core. In particular, a need exists for a turret-style system for
 winding paper onto a core utilizing lighter mandrels to which a core can
 be securely placed so that the production of logs of paper per minute can
 increase in comparison to conventional systems.
 SUMMARY OF THE INVENTION
 The present invention recognizes and addresses the foregoing problems and
 others experienced in the prior art.
 Accordingly, an object of the present invention is to provide an improved
 mandrel system for winding paper.
 It is another object of the present invention to provide a mandrel system
 that can include a turret assembly having mandrels made from light
 materials, such as aluminum.
 Still another object of the present invention is to provide a mandrel
 system that can include a turret assembly and a gas circulation system.
 Yet another object of the present invention is to provide a gas circulation
 system for applying suction forces and positive pressure to a mandrel to
 aid in the positioning and maneuvering of a core on the mandrel during the
 winding process.
 These and other objects of the present invention are achieved by providing
 a mandrel system that includes a turret assembly. In general, any turret
 assembly known in the art can be used in the present invention.
 Specifically, a turret assembly of the present invention can comprise a
 plurality of mandrels rotatably affixed to a turret capable of indexing
 about its longitudinal axis. As such, a mandrel of the present invention
 can be effectively wound with paper as it rotates.
 In one embodiment of the present invention, the turret assembly can index
 the mandrels into a variety of positions or "stations" at which various
 portions of the winding process can occur. For instance, a core can be
 loaded onto a mandrel at one position. A paper web can then be wound on a
 spinning mandrel at another position. Furthermore, a finished roll of
 wound paper can be removed at yet another position.
 In some embodiments, a mandrel system of the present invention can include
 a gas circulation system that operates in conjunction with the turret
 assembly. In general, the gas circulation system can allow the flow of a
 gas, such as air, through one or more mandrels to aid in positioning,
 loading, and removing a core located on a mandrel during the winding
 process. In particular, the gas circulation system can, in some instances,
 provide a suction force to keep the core held into place on the mandrel.
 Moreover, the gas circulation system can also, in other instances, provide
 an outwardly force to the core to aid in loading and removal.
 Generally, when utilized with a gas circulation system, mandrels of the
 present invention typically comprise a hollow channel substantially
 extending the length of the mandrel and an exterior portion containing a
 plurality of perforations. As a result, air can easily flow through the
 mandrel via the hollow channel and plurality of perforations. For
 instance, when applying a suction force, air can be drawn from outside the
 mandrel through the perforations such that it exits the mandrel through
 the hollow channel. Moreover, when applying a positive pressure, air can
 be forced through the hollow channel such that it exits the mandrel via
 the plurality of perforations.
 In general, the perforations can be positioned on the mandrel in any of a
 variety of patterns and/or locations. For instance, in one embodiment, the
 perforations can be distributed along the radial axis of the mandrel such
 that they extend 360.degree. around a cross-section of the mandrel.
 However, in some instances, the use of less perforations may operate to
 grip the core more effectively. As such, in some embodiments, the
 perforations can extend less than 360.degree. around a cross-section of
 the mandrel. For example, in one embodiment, the perforations can be
 distributed along the radial axis of the mandrel such that they extend
 about 180.degree. around a cross-section of the mandrel. In another
 embodiment, the perforations can form a spiral pattern about the mandrel.
 In some embodiments, it may be desired to selectively provide suction
 forces and/or air pressure at certain positions of the winding process.
 For instance, it may be desirable to apply a suction force during paper
 winding, and yet undesirable to apply a suction force during core loading.
 As a result, one embodiment of a gas circulation system of the present
 invention includes a mechanism for controlling the air flow through a
 particular mandrel. For instance, one or more gas flow control devices can
 be used to control the flow of air throughout the system.
 In fact, in one embodiment of the present invention, two gas flow control
 devices are used to control the flow of air. In particular, the first gas
 flow control device contains a vacuum passageway and a pressurized air
 passageway. A vacuum source can communicate with the vacuum passageway
 such that a suction force is continuously supplied thereto. Moreover, a
 pressurized air pump can communicate with the pressurized air passageway
 such that positive pressure is also continuously supplied thereto. In
 addition, in one embodiment, the first gas flow control device remains
 stationary with respect to the indexing turret.
 Moreover, in this embodiment, a second gas flow control device can be
 provided that is rotatably affixed to the turret such that it can index in
 conjunction therewith. The second gas flow control device can comprise a
 plurality of air passageways that correspond to a particular mandrel. For
 example, the second gas flow control device can include six air
 passageways corresponding to six mandrels. Depending on the position of
 the turret, each air passageway can be placed in communication with the
 vacuum passageway or pressurized air passageway of the first gas flow
 control device as the turret and second gas flow control device rotate.
 For example, an air passageway corresponding to a mandrel in the core
 loading position can be placed in communication with the pressurized air
 passageway of the first gas flow control device such that a positive
 pressure can be supplied to the mandrel. Moreover, at the same time, an
 air passageway corresponding to another mandrel in the paper winding
 position can be placed in communication with the vacuum passageway of the
 first gas flow control device such that a suction force can be supplied
 thereto. In some embodiments, it may also be desired that no positive
 pressure or vacuum be supplied to a particular mandrel. In that case, the
 air passageway corresponding to the mandrel is not in communication with
 either the vacuum or pressurized air passageway of the first gas flow
 control device.
 Other objects, features and aspects of the present invention are discussed
 in greater detail below.

Repeat use of reference characters in the present specification and
 drawings is intended to represent the same or analogous features or
 elements of the invention.
 DETAILED DESCRIPTION OF THE INVENTION
 Reference now will be made in detail to the embodiments of the invention,
 one or more examples of which are set forth below. Each example is
 provided by way of explanation of the invention, not limitation of the
 invention. In fact, it will be apparent to those skilled in the art that
 various modifications and variations can be made in the present invention
 without departing from the scope or spirit of the invention. For instance,
 features illustrated or described as part of one embodiment, can be used
 on another embodiment to yield a still further embodiment. Thus, it is
 intended that the present invention cover such modifications and
 variations as come within the scope of the appended claims and their
 equivalents. Other objects, features and aspects of the present invention
 are disclosed in or are obvious from the following detailed description.
 It is to be understood by one of ordinary skill in the art that the
 present discussion is a description of exemplary embodiments only, and is
 not intended as limiting the broader aspects of the present invention.
 In general, the present invention is directed to an improved mandrel system
 for rewinding various types of paper, such as tissue, from large supply
 rolls into smaller rolls. In particular, the present invention is directed
 to a mandrel system that can effectively utilize a gas circulation system
 to aid in the winding process. For instance, it has been discovered that
 gases can be used to aid in various aspects of the winding process,
 including adequately positioning, securing, and removing paper rolls on a
 mandrel. As a result, a system of the present invention can eliminate the
 need for conventional dog systems that could cause damage to the core or
 wound product being formed.
 Moreover, as a result of the present invention, lighter mandrels, such as
 those made from aluminum, can be utilized for winding. In fact, it has
 been discovered that, due to the use of lighter materials, the mandrels
 can rotate and index about the turret at faster speeds and thus produce
 more logs of paper per minute than in the past.
 As stated, a mandrel system of the present invention used for winding paper
 generally comprises a turret assembly. Turret assemblies are well known in
 the art to be useful for winding coreless paper rolls or for winding paper
 onto a core. In general, turret assemblies often include at least one
 mandrel that is rotatably affixed to an indexing mechanism. The indexing
 mechanism, or turret, can rotate a mandrel into a number of positions or
 "stations" at which various steps of the winding process can occur. For
 instance, at one position, the paper can be attached to the mandrel. At
 another position, the paper can be wound around the mandrel. And, at yet
 another position, the wound paper roll can be removed from the mandrel.
 According to the present invention, any turret assembly known in the art is
 suitable for use in the present invention. Examples of various turret
 assemblies that can be used in the present invention include, but are not
 limited to, the turret assemblies described in U.S. Pat. No. 4,133,495 to
 Dowd; U.S. Pat. No. 5,337,968 to De Bin et al.; and U.S. Pat. No.
 5,797,559 to Coffey, which are incorporated herein by reference. One
 particular embodiment of a turret assembly that can used in the present
 invention is depicted in FIGS. 1-4. However, as stated, it should be
 understood that the embodiment depicted in FIGS. 1-4 and described herein
 is but one example of a suitable turret assembly, and that other turret
 assemblies are equally suitable for use in the present invention.
 In this regard, Referring to FIG. 1, one embodiment of a turret assembly of
 the present invention is illustrated. As shown, a turret assembly 6 can
 include a turret 38 attached to various mandrels. As stated above, turret
 38 can generally be indexed into a variety of positions during the winding
 process. For instance, as shown in FIG. 4, the indexing can occur by
 rotating the turret about its longitudinal axis, which is axially carried
 on shaft 250. This rotation of the turret can be accomplished by any of a
 variety of methods known in the art. For example, as shown in FIG. 1,
 turret 38 can be indexed through the rotation of gear 34. In this
 embodiment, the rotation of gear 34 is effected by belt 32, which is
 engaged around pulley 16. Thus, as a result of the rotation of pulley 16
 by a driving mechanism (not shown), turret 38 can be indexed into a
 variety of positions.
 In accordance with the present invention, the turret assembly can also
 include at least one mandrel for winding paper that is rotatably affixed
 to the turret. For instance, as shown in FIGS. 1-3, six mandrels 10, 20,
 30, 40, 50, and 60 can be rotatably affixed to turret 38. Although turret
 assembly 6 is depicted in FIG. 1 as including six mandrels, it should be
 understood that only one mandrel, or any number of mandrels greater than
 one, can also be used in the present invention.
 Accordingly, one embodiment for winding paper onto a core utilizing turret
 assembly 6 will now be described. It should be understood, however, that
 the following description is for illustrative purposes only, and that any
 other method for winding paper can be used with a mandrel system of the
 present invention.
 As shown in FIG. 6D, the winding process can be initiated by first placing
 a core 44 onto mandrel 40 according to any method known in the art. The
 position of mandrel 40 in the embodiments depicted in FIGS. 1-7 can also
 be described as the "core loading position" of turret 38. Once core 44 is
 placed onto mandrel 40, turret 38 can then be indexed into an "adhesive
 application position", which is the position occupied by mandrel 50 in the
 embodiments depicted by FIGS. 1-7. In particular, as illustrated in FIG.
 6A, an adhesive 45 can be applied by any method known in the art to core
 44. Generally, an adhesive used in the present invention can comprise any
 of a variety of materials, such as glue, known to adhere paper to a
 surface. Although not necessarily required, such an adhesive facilitates
 attachment of the paper web onto a core.
 Once adhesive 45 is applied to core 44, mandrel 40 can be indexed by turret
 38 into the "prespin position", which is the position occupied by mandrel
 60 in the embodiments depicted by FIGS. 1-7. At the "prespin position",
 the mandrel can be rotated to ensure that the mandrel achieves a certain
 rotational speed before a paper web is wound thereon. In one embodiment,
 as shown in FIG. 6A, mandrel 60, for example, can be "prespun" in a
 clockwise direction.
 In general, a mandrel of the present invention can be rotated by any manner
 known in the art. For example, as shown in FIG. 1, drive motor pulleys 22
 and 24 can be utilized to spin the mandrels. Specifically, motor pulleys
 22 and 24 can engage drive belts 26 and 28, respectively, which are
 wrapped around secondary pulleys 12 and 14. In one embodiment, as
 illustrated in FIG. 5, motor pulley 22 can maneuver drive belt 26 such
 that it movably contacts pulley engagement device 27, thereby causing
 mandrel 10 to spin, while simultaneously movably contacting pulley
 engagement device 25, thereby causing mandrel 60 to spin. Moreover, to
 assist drive belt 26, motor pulley 24 can maneuver drive belt 28 such that
 it movably contacts pulley engagement device 29, thereby causing mandrel
 10 to spin, while simultaneously-movably contacting another pulley
 engagement device (not shown), thereby causing mandrel 60 to spin.
 As illustrated in FIG. 5, one embodiment of the present invention also
 provides for mandrels having pulley engagement devices of different sizes
 for alternating mandrels such that drive belts 26 and 28 remain staggered
 throughout the winding process. For instance, as shown in FIG. 5, pulley
 engagement device 27 of mandrel 10 can have a smaller diameter than a
 corresponding pulley engagement device 25 for an adjacent mandrel 60.
 Once initially rotated at the "prespin position", the mandrel can then be
 indexed by turret 38 into the "winding position", which is the position
 occupied by mandrel 10 in the embodiments depicted by FIGS. 1-7. The
 rotational speed of the mandrel imparted at the "prespin position" is
 generally greater than the feed speed of the paper web such that, as the
 rotating mandrel is indexed into the "winding position", the paper web can
 wind around the mandrel. Moreover, as shown in FIG. 6A, mandrel 10, for
 example, can be further rotated in a clockwise direction, while in the
 "winding position", by drive belts 26 and 28 such that paper web 11 can be
 wound thereon. In some embodiments, the rotational speed of mandrel 10 can
 be maintained at a substantially constant rate from the time that it first
 contacts the leading edge of paper web 11 until the end of the winding
 period.
 After paper web 11 is wound onto the mandrel, it can then be further
 indexed by turret 38 into a "tail seal position", which is the position
 occupied by mandrel 20 in the embodiments depicted by FIGS. 1-7. At the
 "tail seal position", the unattached portions of paper web 11 can be
 sealed to the roll of paper via a sealing device 19. In some embodiments,
 for example, sealing device 19 can be configured to apply glue or some
 other adhesive to the paper web such that the tail can be sealed thereto.
 As shown in FIG. 1, mandrel 20 can also be rotated by drive belt 22 as
 described above. An external roll (not shown) can also be used for
 rotating mandrel 20 at the "tail seal position" of this embodiment. As
 such, mandrel 20 can rotate at a slower speed, which can aid in the
 sealing process.
 Once sealed, the finished roll of paper can then be removed. In some
 embodiments, as depicted in FIG. 6C, a mandrel containing a finished roll
 of paper can be indexed by turret 38 into a "removal position", which is
 the position occupied by mandrel 30 in the embodiments depicted by FIGS.
 1-7. As illustrated by FIG. 6C, a finished roll of paper web 11 can be
 axially removed from mandrel 30 by any method known in the art.
 To aid in rewinding paper from a large roll into smaller rolls, one
 embodiment of a mandrel system of the present invention includes a gas
 circulation system that can operate in conjunction with the turret
 assembly. When utilizing a gas circulation system, a mandrel of the
 present invention can typically be provided with a hollow channel having
 an exterior portion containing various holes or perforations through which
 air can easily flow. For example, in one embodiment, as shown in FIG. 7A,
 a mandrel generally 400 is depicted having a longitudinal channel 310 that
 substantially extends the length of the mandrel. Moreover, mandrel 400
 also includes an outer wall 320 that is provided with perforations 300
 distributed along the radial axis of the mandrel such that perforations
 300 extend 360.degree. around a cross-section of mandrel 400. In one
 embodiment, air can be circulated through a mandrel at a positive pressure
 to aid in the loading and removal of paper rolls from the mandrel.
 Positive pressure can generally allow an outwardly force to be applied to
 the core or paper roll located on a mandrel and thus facilitate loading
 and removal of paper from the mandrel. For example, as shown in FIG. 8A,
 one embodiment of the present invention includes a system that can
 circulate air at a positive pressure through perforations 300 of mandrel
 400 such that an outwardly force (indicated by arrows) can be applied to a
 core or paper roll located on mandrel 400.
 Moreover, in another embodiment, air can be drawn through a mandrel to
 provide a suction force to a core or paper roll located on the mandrel to
 keep the roll in position during the winding process. For example, as
 shown in FIG. 8B, air can be drawn through perforations 300 of mandrel 400
 such that a suction force (indicated by arrows) can be applied to a core
 or paper roll located on mandrel 400.
 In some embodiments, it may also be desired to use perforations that extend
 less than 360.degree. around any cross-section of the mandrel. For
 instance, as shown in FIG. 7B, outer wall 320 of mandrel 400 can include
 perforations 300 distributed along the radial axis of the mandrel such
 that perforations 300 extend about 180.degree. around a cross section of
 mandrel 400. Moreover, in another embodiment, as shown in FIG. 7C, outer
 wall 320 of mandrel 400 can include perforations 300 distributed along the
 radial axis of the mandrel in a spiral pattern. In some instances, using
 less perforations allows the core to be better gripped and positioned on
 the mandrel.
 In particular, for most applications the paper core placed on the mandrel
 will have a circumference slightly greater than the circumference of the
 mandrel. In some applications, if the perforations were to extend around
 the entire circumference of the mandrel, a paper core placed on the
 mandrel may either be unevenly held or may tend to collapse when a suction
 force is applied. Utilizing perforations that do not extend around the
 entire circumference of the mandrel can allow the mandrel to better hold
 the core and can also allow some compensation for the larger diameter of
 the core.
 The circulation of air through a mandrel of the present invention can
 generally be accomplished through the use of any gas circulation system
 known in the art. Referring to FIGS. 2-4, one embodiment of a gas
 circulation system of the present invention is illustrated. As shown in
 FIG. 4, a vacuum source 76 can be utilized to provide a suction force to
 the mandrels of the present invention. Generally, vacuum source 76 can
 comprise any mechanism known in the art to be capable of supplying a
 suction force, such as a vacuum pump. In one embodiment, vacuum source 76
 can provide a suction force to a core located on mandrel 60, for example,
 by drawing outside air through the perforations of mandrel 60, into
 conduit 160, and through vacuum hose 70. Although air flowing through
 vacuum hose 70 is depicted as exiting to the atmosphere, it can also be
 recirculated for applying a positive pressure to other sections of the gas
 circulation system.
 In addition to vacuum source 76, air at a positive pressure can also be
 supplied by an air source 86 in accordance with the present invention.
 Generally, air source 86 can comprise any mechanism known in the art to be
 capable of supplying a positive pressure, such as a pressurized pump. In
 one embodiment, air source 86 can provide a positive pressure to mandrel
 40, for example, by forcing air through hose 84 into conduit 140 such that
 it then flows through the channel and perforations of mandrel 40.
 In many cases, a suction force and a positive air pressure may only be
 desired at certain "positions" of the winding process. For example, a
 suction force can often be useful when applying an adhesive to the core,
 prespinning the core, and/or winding paper onto the core to help control
 the position of the core on the mandrel. However, a suction force may
 conversely be undesirable in other positions of the winding process, such
 as when loading or removing a core from a mandrel, because a suction force
 could make it difficult to maneuver the core or paper roll as needed. In
 fact, in these positions of the winding process, it may instead be
 desirable to apply a positive pressure to the core. Consequently, a gas
 circulation system of the present invention can, in some embodiments, be
 provided with a mechanism for controlling the flow of gas so as to control
 the type of force applied at each winding position .
 Referring again to FIGS. 2-4, one embodiment of a gas circulation system
 provided with a mechanism for controlling gas flow is illustrated. In this
 embodiment, gas flow control devices 90 and 98 can be utilized to control
 the flow of air through a system of the present invention. Although the
 use of two gas flow control devices, such as valves, is shown and
 described herein, it should be understood that any number of gas control
 devices can be adapted to provide adequate gas flow control in a system of
 the present invention.
 As shown in FIG. 4, gas flow control device 90 can be rotatably affixed to
 turret 38 so that it moves in conjunction with turret 38. Gas flow control
 device 90 can comprise a plurality of holes that typically correspond to
 the number of mandrels. For example, as shown in FIG. 3, gas flow control
 device 90 includes six holes 75 that correspond with each mandrel. Each
 hole 75 is connected to an air passageway that communicates with a
 particular mandrel. For instance, as shown in FIGS. 3-4, one hole of gas
 flow control device 90 can communicate with air passageway 140
 corresponding to mandrel 40. Moreover, another hole of gas flow control
 device 90 can communicate with air passageway 160 corresponding to mandrel
 60.
 One embodiment of a gas circulation system of the present invention can
 also include gas flow control device 98. As shown in FIGS. 2-4, gas flow
 control 98 can include a vacuum passageway 72 and two stationary air
 passageways 74 to help control the flow of air. Moreover, gas flow control
 device 98 can also be placed in communication with gas flow control device
 90. In particular, gas flow control device 98 typically remains stationary
 with respect to turret 38 and gas flow control device 90. In some
 embodiments, for example, gas flow control device 98 can be affixed to the
 ground via a frame or other device (not shown) of the turret assembly.
 Because gas flow control device 90 rotates with turret 38, while gas flow
 control device 98 remains stationary, vacuum and pressurized air can be
 continuously applied to multiple mandrels in a system of the present
 invention based on the position of each mandrel. In particular, vacuum
 source 76 can continuously draw air through vacuum passageway 72 of gas
 flow control device 98. Thus, as gas flow control device 90 rotates,
 various passageways of device 90 corresponding to a certain mandrel can be
 placed in communication with stationary vacuum passageway 72. Furthermore,
 positive air pressure can also be continuously applied by air source 86 to
 gas flow control device 98 via stationary air passageways 74. Thus, as gas
 flow control device further rotates, various holes 75 of device 90
 corresponding to a certain mandrel can be placed in communication with
 stationary passageways 74.
 To better illustrate the operation of a gas circulation system of the
 present invention, the embodiments illustrated in FIGS. 2-4 will now be
 described in more detail. As shown, mandrel 40 is located in the "core
 loading" position at which a core (not shown) is being loaded thereon. To
 facilitate loading, a positive pressure can be supplied to the mandrel by
 air source 86. In particular, when turret 38 indexes mandrel 40 into the
 "core loading position", air passageway 140 of mandrel 40 can be placed in
 communication with stationary air passageway 74 via hole 75. While in this
 position, air source 86 can supply a positive air pressure to mandrel 40
 to aid in the loading process.
 After loading is completed, turret 38 can then index into the "adhesive
 application position", which is occupied by mandrel 50. In this position,
 a suction force can be applied by vacuum source 76 to mandrel 50 to keep
 the core located thereon in position during adhesive application. In
 particular, when turret 38 indexes the mandrel into the "adhesive
 application position", air passageway 150 of mandrel 50 can be placed in
 communication with stationary vacuum passageway 72 of flow control device
 98. While in this position, vacuum source 76 can therefore supply a
 suction force to the mandrel to keep the core properly positioned during
 winding.
 As described in more detail above, turret 38 can also be indexed to a
 variety of other winding positions. For instance, as shown in FIG. 3,
 mandrels 60 and 10 can also be placed in communication with vacuum
 passageway 72 via air passageways 160 and 110, respectively, such that a
 suction force can be applied to help keep the core in position while
 winding paper thereon. Moreover, air passageway 130 of mandrel 30
 ("removal position") can be placed in communication with stationary air
 passageway 74 such that a positive air pressure can be applied to aid in
 removal of the core. In some embodiments, a particular position may
 require neither a suction force nor a positive pressure. For example, as
 shown in FIG. 3, air passageway 120 of mandrel 20 ("tail seal position")
 is not in communication with vacuum passageway 72 or stationary air
 passageways 74.
 Although a gas circulation system of the present invention has been
 described herein with respect to one method of winding paper onto a core,
 it should also be understood that other methods of winding paper are
 equally suitable for use in the present invention. For example, in some
 embodiments, it may be desired to apply a suction force to mandrels at
 different positions, to refrain from using positive air pressure, to use
 gas flow at only one position, etc. Moreover, in some embodiments, it may
 not be necessary to utilize any gas flow to aid in the winding process.
 These and other modifications and variations to the present invention may
 be practiced by those of ordinary skill in the art, without departing from
 the spirit and scope of the present invention, which is more particularly
 set forth in the appended claims. In addition, it should be understood
 that aspects of the various embodiments may be interchanged both in whole
 or in part. Furthermore, those of ordinary skill in the art will
 appreciate that the foregoing description is by way of example only, and
 is not intended to limit the invention so further described in such
 appended claims.