The invention relates to web accumulators and methods for accumulating and discharging a reserve portion of a continuous web passing through the accumulator. The invention enables continuous operation of processing stations on either or both sides of the accumulator when the speed of the web moving through the processing stations temporarily varies between the two stations. The invention is particularly useful for handling webs that tend to wrinkle or fold over during processing.
In many processing operations involving continuous lengths of web material, there are temporary differences in operating speeds between two adjacent operating stations. For example, in the manufacture of absorbent articles, it is common to unwind raw materials from large supply rolls and conduct them into a converting operation. In such operations, it is desirable to unwind subsequent supply rolls without shutting down the converting operation. The operation is desirably maintained by splicing a new supply web to the end of the expiring supply web. This would require stopping the converting operation unless a reserve portion of the expiring web had been accumulated for continued operation while a new supply roll is prepared. This problem is quite old and is generally solved through the use of web accumulators.
The typical accumulator for such use is the festooning type. Festooning type accumulators typically consist of a set of fixed web rolls and a set of movable web rolls which are moved away from the fixed rolls for accumulating a reserve portion of the web and moved toward the fixed rolls for discharging the accumulated reserve portion of the web.
The web is typically looped alternately from a roll of the first set to a roll of the second set in consecutive order. In these configurations, there is typically about 180 degrees of wrap contact between the rolls and the web to maximize the capacity of the accumulator relative to the length. This configuration generally results in significant tractional forces between the web and the rolls and may not be suitable for webs having extensibility in the cross-machine direction (CD extensible webs) because of wrinkling.
It is also known through prior joint development to accumulate webs having machine direction extensibility (MD extensible webs) by running at tensions below 0.05 pounds per lineal inch of web. The MD extensible web is susceptible to clinging and wrapping as the web passes from one set of rolls to the other set, at least in part, because of the low tension. To address this issue, the spacing between web passes is increased relative to conventional accumulators. To increase the spacing between web passes, the web is alternately looped from two rolls in the first set to two rolls in the second set in consecutive order and the two rolls are spaced apart in the machine direction by 1 to 2.5 times the diameter of the roll. This configuration results in less than 180 degrees of wrap contact between the rolls and the webs. While designed for accumulating MD extensible webs at very low tensions, this apparatus and method have been used to accumulate other webs at tensions up to 0.15 pounds per lineal inch.
However, there still exists a need for a web accumulator and a method of web accumulation adapted for CD extensible webs.
In response to the discussed need, the present invention provides a method and apparatus for accumulating and discharging a web. In one aspect, a method includes providing a web to an accumulator; providing a first set of rotatably mounted web rolls comprising at least one subset of rolls linked together and adapted to pivot; providing a second set of rotatably mounted web rolls comprising at least one subset of rolls linked together and adapted to pivot; pivoting the subsets of the first set and the subsets of the second set from a generally horizontal alignment to a generally vertical alignment; moving the second set of rolls past the first set of rolls to define a thread condition; passing the web between the first set of rolls and the second set of rolls; moving the second set of rolls past the first set of rolls to engage the web; pivoting the subsets of the first set and the subsets of the second set from the generally vertical alignment to the generally horizontal alignment to define a run condition; moving the web alternatively between subsets of the first set and subsets of the second set; and moving the second set of rolls away from the first set of rolls to accumulate the web and moving the second set of rolls towards the first set of rolls to discharge the web.
In various embodiments, the web may be extensible in the cross-machine direction. In various embodiments, the web may be elastic slit-necked spunbond.
In various embodiments, the method may further include moving the web with at least 0.075 pounds per lineal inch tension. In various embodiments, the second set of web rolls may be adapted to move vertically past the first set of web rolls when in the thread condition but not in the run condition.
In various embodiments, the method may further include moving the second set of rolls past the first set of rolls by aligning notches in a moveable carriage with portions of a support frame and aligning notches in the support frame with portions of the moveable carriage.
In another aspect, a web accumulator includes at least one first set and at least one second set of rotatably mounted web rolls. The accumulator has a thread condition and a run condition and the second set of web rolls are adapted to move past the first set of web rolls in the thread condition but not in the run condition.
In various embodiments, the first set of web rolls and the second, set of web rolls may have a diameter and may include subsets of rolls. The subsets of rolls may include two rolls per subset and the subsets may have a spacing less than one times the diameter.
In various embodiments, the first set of rolls and the second set of rolls may include carbon fiber and may have sleeves comprising fluoropolymer resins, clear epoxy coatings, nylon, or ultra high molecular weight polymers.
In various embodiments, the first set rolls may be rotatably mounted to a fixed support structure and the second set of rolls may be rotatably mounted to a moveable carriage. The moveable carriage may include notches adapted to align with portions of the support structure and the fixed support structure may include notches adapted to align with portions of the moveable carriage.
In various embodiments, the at least one of the first and second web sets may include at least two consecutive rolls linked together and adapted to pivot between a thread condition and a run condition. In various embodiments, the at least two consecutive rolls may be staggered in the run condition. In various embodiments, the at least two consecutive rolls may be generally aligned in a machine direction in the run condition and generally aligned in a vertical direction in the thread condition.
In various embodiments, the first set and the second set of rolls may have a diameter and include subsets of rolls having two rolls per subset. The subsets may have a spacing less than one times the diameter.
In another aspect, a web accumulator includes at least one first set of rolls. The first set of rolls has at least one subset which has two consecutive staggered rolls. The web accumulator also includes at least one second set of rolls. The second set of rolls has at least one subset which has two consecutive staggered rolls. The second set of rolls may be adapted to move relative to the first set of rolls. The web accumulator also has a web path defined by the two consecutive staggered rolls of the first set followed by the two consecutive staggered rolls of the second set.
In various embodiments, the first set of rolls may include three or more subsets having two consecutive staggered rolls. The second set of rolls may have three or more subsets having two consecutive staggered rolls. The web path may be adapted to sequentially alternate between subsets in the first set and subsets in the second set.
In various embodiments, the staggered rolls may be overlapped in a machine direction. In various embodiments, the subsets may have a first roll and a second roll. The second roll may have a wrap contact angle and the first roll may have a wrap contact angle less than the wrap contact angle of the second roll. In various embodiments, the contact angle of the first roll may be no greater than 60 degrees and the contact angle of the second roll may be no less than 120 degrees.
a representatively illustrates a cross-sectional view of a first exemplary wrap contact angle.
b representatively illustrates a cross-sectional view of a second exemplary wrap contact angle.
Referring to
The movable second set of web rolls 24 may be joined to a single carriage 25. The carriage 25 may be moved away from the fixed first set of web rolls 22 for accumulating a reserved portion of the web 26 and moved toward the fixed first set of web rolls 22 for discharging the accumulated reserve portion of the web 26.
As used herein, the term “set” describes a group of rotatably mounted web rolls wherein each web roll remains in the same position relative to the other web rolls within the same group in the run condition. For example, three rolls mounted to a single moveable carriage are in the same set because they remain in the same position relative to each other in the run condition even as the carriage moves. In another example, five fixed position rotatably mounted web rolls are in the same set because they remain in the same position relative to the other web rolls within the same group in the run condition.
As used herein, the term “web path” describes the route by which one or more substrates are adapted to move through a processing module, such as, for example, a web accumulator.
Referring now to
While not wishing to be bound by theory, it is believed that webs moving over rolls are subject to at least two forces: tractional forces and flattening forces. Referring now to
As used herein, the terms “degree of wrap contact” or “wrap contact”describe the amount of roll circumference that is in contact with a web moving over the surface of the roll.
Referring now to
As illustrated in
In
For example, in
In various embodiments, the subset width W may be less than 3, less than 2½, or less than 2 l/4 times the roll diameter, D. In various embodiments, the clearance distance, C, may be less than 3½, less than 3, less than 2½, or less than 2¼ times the roll diameter, D. In various embodiments, the spacing, S, may be less than 2, less than 1, less than ½ or less than ¼ times the roll diameter, D.
As illustrated in
In
In
Referring now to
As illustrated in
In
In various embodiments, the clearance distance, C, may be less than 2½, less than 2, less than 1½, less than 1, less than ½, or less than ¼ times the roll diameter, D. In various embodiments, the subset width, W, may be less than 3, less than 2½, or less than 2¼ times the roll diameter, D. In various embodiments, the spacing, S, may be less than 2, less than 1½, less than 1, less than ½, or less than ¼ times the roll diameter, D.
As illustrated in
In
Comparing the accumulator 110 of
Referring now to
The first set of web rolls 162 includes subsets having two rolls per subset. For example, rolls 170 and 171 comprise a subset 151. Likewise, rolls 174 and 175, 178 and 179, and 182 and 183 comprise subsets 153, 155 and 157 respectively. Each roll in each subset is connected to the other roll in the subset by a linkage. For example, the rolls of subset 151 are connected by a linkage 189. Likewise, the rolls of subsets 153, 155 and 157 are connected by linkages 191, 193 and 195 respectively.
In various embodiments, the first set of web rolls 162 are rotatably mounted to one or more structures. The structures may be a support frame, linkages, a carriage, and the like. The structures may be fixed or may be moveable in a vertical direction 45. In
The second set of web rolls 164 includes subsets having two rolls per subset. For example, rolls 172 and 173 comprise a subset 152. Likewise, rolls 176 and 177, 180 and 181, and 184 and 185 comprise subsets 154, 156 and 158 respectively. The rolls of subsets 151, 153, 155 and 157 are connected by linkages 190, 192, 194 and 196 respectively.
In
In various embodiments, the subsets may pivot in either direction. In various embodiments, one or more first subsets may pivot in a different direction than one or more second subsets within the same set. In various embodiments, only subsets of the first set or only subsets of the second set may be adapted to pivot.
In some embodiments, two or more subsets may be connected by a master linkage which may be adapted to pivot the two or more subsets. In various embodiments, any number of subsets may be controlled with one or more master linkages. In various embodiments, the one or more master linkages may move in any direction suitable to pivot the attached subsets.
For example, subsets 152, 154, 156 and 158, as illustrated, are connected by a master linkage 197 such that movement of the master linkage 197 in the direction indicated by arrow 198 results in each of the subsets 152, 154, 156 and 158 pivoting simultaneously in the direction indicated by the arrow 200. In various embodiments, any number of subsets may be controlled with one or more master linkages.
As illustrated in
As illustrated in
After threading the web 168 through the accumulator 160, the second set of rolls 164 are adapted to move vertically past the first set of rolls 162 to engage the web 168. After the second set of rolls 164 engages the web 168 and clears the first set of rolls 162 the first set of rolls 162 are adapted to pivot in the direction 199 and the second set of rolls 164 are adapted to pivot in the direction 200 thereby transitioning the accumulator 160 into a run condition as illustrated in
Referring now to
The web 168 moves in a direction indicated by arrow 166 generally in a machine direction 44 along the web path 169. The web 168 is looped alternately from a subset, including two consecutive web rolls, in the first set of web rolls 162 to a subset, including two consecutive web rolls, in the second set of web rolls 164 to define the web path 169 through the accumulator 160. The web path 169, as illustrated, is adapted such that the web 168 has less than 135 degrees of wrap contact with any given roll in the accumulator 160 in the run condition and each roll is adapted to form part of the web path.
The web 168 moves along the web path 169 in the direction 166 passing from roll to roll in the following order: 170, 171, 172, 173, 174,175, 176, 177, 178, 179, 180, 181, 182, 183, 184, 185, and 186 before exiting the accumulator 160.
Optionally, the subsets of this embodiment may be only partly pivoted in the run mode thereby resulting in a staggered configuration similar to that illustrated in
As illustrated in
Comparing the accumulator 160 of
Referring now to
As illustrated in
In
In
In various embodiments, the subset width, W, may be less than 2, less than 1¾, less than 1½, or less than 1¼ times the roll diameter, D. At one times the roll diameter, D, the rolls would be vertically aligned and would not benefit from the reduced contact angle as disclosed herein.
In various embodiments, the clearance, C, may be less than 4, less than 3, less than 2, less than 1¾, or less than 1½ times the roll diameter, D. To provide through threading, the clearance, C, should be greater than the subset width, W, in the thread condition. However, if through threading is not desired, the clearance, C, may be equal to or less than the subset width, W, in the thread condition.
In various embodiments, the spacing, S, may be less than 1, less than ½, or less than ¼ times the roll diameter, D. In various embodiments, there may be staggered rolls having no overlap, O. In other embodiments, the overlap, O, may be at least ¼, ½ or ¾ times the roll diameter, D.
As illustrated in
In various embodiments, the accumulators described herein may have at least one first set of rolls and at least one second set of rolls. In some embodiments, the accumulator may have 3, 4, 5, 6, 7, or more than 8 sets of rolls. In various embodiments, the web path may alternate between at least two rolls of a first set and at least two rolls of a second set.
In various embodiments, the accumulators described herein may include one or more rolls having less than 180, less than 135, or less than 100 degrees of wrap contact. In some embodiments, one or more rolls may have about 90 degrees of wrap contact. In some embodiments, at least 3, 4, 5, 6, 7, 8, 9 or 10 rolls have a wrap contact less than 100, 120, 135, 140, 160, or 180 degrees.
In various embodiments, the accumulators described herein may include one or more sets of rolls having one or more subsets of rolls. For example, one or more sets of rolls may include 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 or more than 10 subsets. In various embodiments, a subset of rolls may include 2, 3, 4, 5 or more than 5 rolls. In various embodiments, one or more sets of rolls may include one or more subsets of rolls and may also include one or more single rolls that are part of the set but are not part of a subset. In various embodiments, one or more sets of rolls may include two or more subsets of rolls wherein the subsets have a different number of rolls. For example, a set of rolls may include two subsets wherein the first subset has two rolls and the second subset has three rolls.
In various embodiments, the accumulators described herein may include a web path that moves from a first subset of rolls in the first set to a first subset of rolls in the second set to a second subset of rolls in the first set to a second subset of rolls in the second set continuing to alternate between sets and subsets until the web exits the accumulator. Each time the web leaves a set of rolls and moves to a different set of rolls it makes a web pass. In various embodiments, the accumulator may include at least 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10 web passes. In some embodiments, the accumulator may include more than 10 web passes.
Suitable rolls for use with the accumulators described herein are known in the art. For example, suitable rolls may be purchased from Advanced Composite Products and Technology Incorporated having offices at 15602 Chemical Lane, Huntington Beach, Calif., USA.
The rolls discussed herein may be made of any suitable materials, such as, for example, metal or carbon fiber composites. The rolls discussed herein may include any suitable surfaces, such as, for example, hard anodized finishes, TEFLON® brand fluoropolymer resins, clear epoxy coatings, NYLATRON® brand wear resistant nylon and ultra high molecular weight polymers. The rolls may include any suitable shape, such as, for example, straight, concave or convex. The rolls may be driven or may rotate freely or may include combinations of driven and freely rotatable rolls.
While not wishing to be bound by theory, it is believed that reducing tractional forces by reducing friction in conjunction with reduced wrap contact provides even greater web flattening benefits because propagating wrinkles can slide across the surface of the rolls.
The rolls discussed herein may be any suitable diameter, such as, for example, 0.5 inches (1.27 cm) to 8 inches (20.32 cm). In various embodiments, suitable rolls have a diameter of 1.115 inches (2.8321 cm).
The carriages discussed herein may include any suitable structure and may be moveable via any suitable means, such as, for example, moving on low friction ball bushing shafting. The carriages may include tension applied thereto by any suitable means, such as, for example, air cylinders acting on the carriage.
The sets of rolls discussed herein may be rotatably mounted to support structures such as, for example, carriages, frames, linkages, and the like, and combinations thereof. The support structures may be adapted to allow through threading by removing portions of one or more support structures such that one or more sets of rolls mounted thereto may pass one or more other sets of rolls without interference between the support structures.
For example, in
The fixed support frame 213 and the vertically movable carriage 215, as illustrated, are adapted such that the second set of rolls 214 can move past the first set of rolls 212 in the thread condition without interference between the frame 213 and the carriage 215. In this embodiment, the frame 213 and the carriage 215 have offset notches 238 that are adapted to allow the second set of rolls 214 to pass below the first set of rolls 212. The method of using the apparatus includes aligning the notches 238 in the carriage 215 with portions of the support frame 213 and aligning the notches 238 in the support frame 213 with portions of the moveable carriage 215. As such, the web 230 can be threaded through the accumulator 210 on the path 232 without wrapping the web 230 about the various rolls.
The generally vertical alignment of the subsets in the thread condition allows for a more compressed accumulator 210 having reduced wrap contact while still allowing for through threading.
After threading the web 230 through the accumulator 210, the second set of rolls 214 are adapted to move vertically past the first set of rolls 212 to engage the web 230. After the second set of rolls 214 engages the web 230 and clears the first set of rolls 212, the first set of rolls 212 and the second set of rolls 214 may be pivoted into alignment generally in the machine direction 44 thereby transitioning the accumulator 210 into a run condition as illustrated in
Referring now to
The web 230 moves in a direction indicated by arrow 234 along the web path 236. The web 230 travels alternately from two consecutive web rolls in the first set of web rolls 212 to two consecutive web rolls in the second set of web rolls 214 to define the web path 236 through the accumulator 210. The web path 236, as illustrated, is adapted such that the web 230 has less than 135 degrees of wrap contact with any given roll in the accumulator 210 in the run condition. Additionally each roll in each set is adapted to form part of the web path 236. The web 230 moves along the web path 236 in the direction 234 passing from roll to roll before exiting the accumulator 210.
One skilled in the art will readily identify alternative adaptations allowing the second set of rolls 214 to vertically pass the first set of rolls 212. For example, the first set of rolls 212 may be cantilevered from one side whereas the second set of rolls 214 may be cantilevered from the opposite side. As such, the rolls may pass without interference from the supporting structures.
The apparatus and methods described herein may be suitable for use with a wide variety of web materials such as, for example, materials having low rigidity in a cross-machine direction, such as, for example CD extensible webs including CD elastic webs. Suitable CD extensible webs include slit elastic fibrous nonwoven laminates as disclosed in U.S. Pat. No. 5,804,021 issued Sep. 8, 1998 to Abuto et al, the entirety of which is incorporated herein by reference where not contradictory. Other suitable CD extensible webs include neck bonded fibrous nonwoven laminates, slit elastic spunbond laminates, slit-necked spunbond laminates, and the like. Other suitable laminates include those taught in commonly assigned U.S. application Ser. No. 11/021,432 to Morman filed Dec. 23, 2004 and U.S. Pat. No. 6,785,937 to Morman et al. issued Sep. 7, 2004, the entirety of both are incorporated herein in their entirety where not contradictory.
In various embodiments, the webs may have any suitable basis weights. In various embodiments, suitable webs may have basis weights of 10 grams per square meter (gsm) to 110 gsm. In some embodiments, suitable webs may have basis weights of 12-34 gsm. In other embodiments, suitable webs may have basis weights of 20-22 gsm.
The apparatus and methods described herein may be suitable for use with web materials that can be processed under tension in the machine direction. For example, the method described herein may include applying and maintaining tension in the machine direction. In some embodiments, the webs may be moved through the accumulators described herein while maintaining at least 0.6 pounds of tension. In some embodiments, the webs may be moved through the accumulators while maintaining at least 0.075 pounds tension per lineal inch of web. In some embodiments, the webs may be moved through the accumulators while maintaining at least 0.1, 0.2, 0.3, 0.4, 0.5, 0.6 or 0.7 pounds tension per lineal inch of web. In some embodiments, the webs may be moved through the accumulators while maintaining 0.075 to 0.75 pounds tension per lineal inch of web.
The apparatus described herein may be suitably used to accumulate and discharge various webs as described above. One suitable method for using the apparatus depicted in
The web path 67 is defined by the web 68 being moved in the direction 66 to a first subset of rolls 96 in the first set of rolls 102. The web 68 sequentially contacts rolls 70 and 71 before making a web pass 69 to a second subset of rolls 98. The second subset of rolls 98 includes rolls 72 and 73. The web 68 is moved sequentially in contact with and past the rolls 72 and 73 before making a web pass 95 to roll 74 and roll 75. The web 68 continues to be alternated between two consecutive rolls in the first set of rolls 62 and two consecutive rolls in the second set of rolls 64 and two consecutive rolls in the first set 62 and so forth until the web 68 passes roll 94 and exits the accumulator 60. The web path 67, as illustrated, is adapted such that the web 68 has less than 135 degrees of wrap contact with any given roll 70-94 as the web 68 is moved through the accumulator 60. Each roll is adapted to form a part of the web path 67.
In various embodiments, each roll is adapted to have less than 180, less than 170, less than 160, less than 150, less than 140, less than 130, less than 120 or less than 110 degrees of wrap contact.
One suitable method for using the apparatus depicted in
In various embodiments, each roll is adapted to have less than 180, less than 170, less than 160, less than 150, less than 140, less than 130, less than 120 or less than 110 degrees of wrap contact.
One suitable method for using the apparatus depicted in
Once the web 168 is passed through the accumulator 162, the second set of rolls 164 is moved in the vertical direction 45 past the first set of rolls 162 to engage the web 168. The subunits 151, 152, 153, 154, 155, 156, 157 and 158 are pivoted such that the rolls that comprise the subunits are essentially oriented in the machine direction 44 resulting in the web path 169 illustrated in
The web path 169 includes the web 168 being moved in the direction 166 to a first subset of rolls 151 in the first set of rolls 162. The web 168 sequentially contacts rolls 170 and 171, before making a web pass to a second subset of rolls 152. The second subset of rolls 152 includes rolls 172 and 173. The web 168 is sequentially moved past rolls 172 and 173 before making a web pass to roll 174. The web 168 continues to be alternated between two consecutive rolls in the first set of rolls 162 and two consecutive rolls in the second set of rolls 164 until the web passes roll 186 and exits the accumulator 160. The web path 169, as illustrated, is adapted such that the web 168 has less than 135 degrees of wrap contact with any given roll 170-186 as the web 168 is moved through the accumulator 160.
In various embodiments, each roll is adapted to have less than 180, less than 170, less than 160, less than 150, less than 140, less than 130, less than 120 or less than 110 degrees of wrap contact.
One suitable method for using the apparatus depicted in
The accumulator 260 of
In various embodiments, the first roll 292 may be adapted to have less than 180, less than 170, less than 160, less than 150, less than 140, less than 130, less than 120, less than 110, less than 100, less than 90, less than 80, less than 70, less than 60, less than 50, less than 40, less than 30, less than 20 or less than 10 degrees of wrap contact.
In various embodiments, the second roll 294 may be adapted to have less than 180, less than 170, less than 160, less than 150, less than 140, less than 130, less than 120, less than 110, less than 100, less than 90, less than 80, less than 70, less than 60, less than 50, less than 40, less than 30, less than 20 or less than 10 degrees of wrap contact. In various embodiments, the wrap contact of the first roll 292 may be greater than, less than, or equal to the wrap contact of the second roll 294.
The accumulators and methods disclosed herein have been described having the sets of rolls moving relative to each other in the vertical direction. However, those skilled in the art will readily appreciate that the same principles are equally applicable to accumulators having the sets of rolls moving relative to each other in the horizontal direction (machine direction) or the cross-machine direction.
While the invention has been described in detail with respect to specific aspects thereof, it will be appreciated that those skilled in the art, upon attaining an understanding of the foregoing, may readily conceive of alterations to, variations of and equivalents to these aspects. Accordingly, the scope of the present invention should be assessed as that of the appended claims and any equivalents thereto.
This application claims priority to provisional application Ser. No. 60/748,527 entitled Method and Apparatus for Accumulating a Web and filed in the U.S. Patent and Trademark Office on Dec. 7, 2005. The entirety of provisional application Ser. No. 60/748,527 is hereby incorporated by reference.
Number | Date | Country | |
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60748527 | Dec 2005 | US |