Patent Application
20070215741
The present invention relates to a process for converting large rolls of wound web material into a finally wound product suitable for use by a consumer.
Web winders are typically used to form large rolls of wound web material, such as paper and polymeric film materials, known as parent rolls. From the parent rolls, rewinders are employed in order to wind the web material into a rolled product. The rolled product is then cut at designated lengths into the finally wound product. The finally wound products typically created by the machines and processes are toilet tissue rolls, paper toweling rolls, paper rolls, polymeric films, and the like.
There are essentially two types of techniques known in the art for performing the step of rewinding; that is, winding a web material from a parent roll into a rolled product. The first technique used in winding the web material to form a rolled product is known as surface winding. In surface winding, the web material is wound onto the core via contact with belts and/or rotating rolls. A nip is typically formed between these two or more co-acting belt or roller systems. The belts or rollers of such systems typically travel in opposite directions at different speeds. The reason for having different speeds lies in the fact that the core that is being driven by the opposed belts or rollers will advance in the direction of the faster moving belt or roller. Usually, these belts or rollers are divergent so that the rolled product that is being built upon the core will have enough space to grow in diameter and will be able to maintain contact with the two diverging belts or rollers. Exemplary surface winders are disclosed in U.S. Pat. Nos. 3,630,462; 3,791,602; 4,541,583; 4,723,724; 4,828,195; 4,856,752; 4,909,452; 4,962,897; 5,104,155; 5,137,225; 5,226,611; 5,267,703; 5,285,979; 5,312,059; 5,368,252; 5,370,335; 5,402,960; 5,431,357; 5,505,405; 5,538,199; 5,542,622; 5,603,467; 5,769,352; 5,772,149; 5,779,180; 5,839,680; 5,845,867; 5,909,856; 5,979,818; 6,000,657; 6,056,229; 6,565,033; 6,595,458; 6,595,459; 6,648,266; 6,659,387; 6,698,681; 6,715,709; 6,729,572; 6,752,344; 6,752,345; and 6,866,220. The following international applications also provide exemplary surface winders: International Publication No. 01/16008 A1, 02/055420 A1, 03/074398 A2, 99/02439, 99/42393, and EPO Application No. 0514226 A1.
However, such winders can have drawbacks. First, a typical surface winder provides significant contact between the web material and the winding surfaces during winding. This contact during winding can effectively translate winding torque through the web material leading to crushing of embossments that may be disposed upon an embossed material, smudging images disposed upon a web material having an image disposed thereon, and the like. Also, surface winders are known to exhibit winding log instability during the winding of low density products.
The second technique used to wind a web material to form a rolled product is known as center winding. In center winding, a core is rotated in order to wind a web material into a roll around a core. Typically, the core is mounted on a mandrel that rotates at high speed at the beginning of a winding cycle and then slows down as the size of the rolled product being wound upon the core increases in diameter. Center winders work well when the web material that is being wound has a printed, textured, or slippery surface. Additionally, center winders can be useful in producing softer rolled products. Exemplary center winders are discussed in U.S. Pat. Nos. 1,040,188; 2,769,600; 3,697,010; 4,588,138; 5,497,959; 5,660,349; 5,725,176; and U.S. Patent Application No. 2002/0130212 A1.
However, center winders have drawbacks that are known to those of skill in the art. Known drawbacks include the need to provide a harder “pull” when rolling high density and low density web materials into a high density roll. This “pull” (tension) can provide for a Poisson lateral contraction of the web material resulting in a non-uniformly wound product. Additionally, the application of tension to a perforated web material can cause the web material to rupture at a perforation during processing. This can cause a processing line to shut down.
It is clear that the prior art lacks a winder or a rewinder capable of performing both center winding and surface winding in order to take advantage of the positive attributes that both processes enjoy. For example, it would be desirable to provide a winder that is capable of allowing a broader range of finished product roll densities. As would be appreciated by one of skill in the art, this capability, when coupled with known capabilities for imparting perforations at desired intervals and sheet counts in increments of one, can provide for a greatly enhanced product converting flexibility. This, in turn, can allow multiple finished product designs to be achieved using a common substrate. This is believed to provide substantial manufacturing expense savings by reducing change-overs on paper machines and converting lines, thereby avoiding multiple parent roll inventories and the like. Such a desired hybrid winding system can also provide the capability to wind thick, highly embossed web materials into preferred high density finished product rolls having low sheet tension. As would be appreciated by one of skill in the art, this can improve product quality by eliminating sheet elongation and embossment distortion, as well as improving winding reliability by providing fewer web material feed breaks in the winding process.
The present invention provides for a method for rewinding a web material. The method comprises the steps of: (1) Disposing the web material on a winding spindle, the winding spindle being operatively associated with a winding turret; (2) Cooperatively engaging a contact roll with the winding spindle when the web material is disposed therebetween, the contact roll being operatively associated with the winding turret; and, (3) Adjusting the position of the contact roll upon said winding turret relative to the winding spindle as the web material is being disposed upon the winding spindle.
In the prior art, a winder or reel is typically known as a device that performs the very first wind of that web material generally forming what is known as a parent roll. A rewinder, on the other hand, is generally known as a device that winds the web material from the parent roll into a roll that is essentially the finished product. For purposes of the present application, the words “winder” and “rewinder” are interchangeable with one another in assessing the scope of the present claims.
The terms machine direction, cross-machine direction, and Z-direction are generally relative to the direction of travel of a web material or interleaved web segments. The machine direction (MD) is known to those of skill in the art as the direction of travel of the web material or interleaved web segment. The cross-machine direction (CD) is orthogonal and co-planar thereto. The Z-direction is orthogonal to both the machine and cross-machine directions.
Referring now to the drawings,
The perforation roll 32 preferably perforates web material 22 upstream of the winder 20. The web slitter roll 34 can provide for the machine direction slitting of web material 22 into two or more portions. The resulting portions of slit web material 22 can then be processed separately or concurrently by either the same or a plurality of web processing systems as would be known to one of skill in the art.
In the exemplary web winding system, as web material 22 travels in direction T, the web material 22 is preferably routed around a portion of the circumference of a bed roll 36 and through a gap disposed between the bed roll 36 and chop-off roll 38. In a preferred embodiment, the bed roll 36 and chop-off roll 38 are concurrently rotated. In a preferred embodiment, chop-off roll 38 is provided with a plurality of blades. Preferably, the bed roll 36 is provided with a plurality of blades that mesh with the blades disposed upon chop-off roll 38 in the gap disposed between bed roll 36 and chop-off roll 38. In an exemplary but non-limiting embodiment, the web material 22 is constrained to a path defined by the blades disposed upon each of bed roll 36 and chop-off roll 38. Applicants believe the web material 22 to be stretched by the relative blade movement and subsequent failure at a line of weakness disposed upon, or within, web material 22 by perforation roll 32.
As would be known to one of skill in the art, after the web material fails at a line of weakness disposed upon, or within, web material 22 by perforation roll 32, the downstream portion of the web material 22 proceeds through the converting process as the tail of the last separated portion of web material 22. This web material portion is then wound into a roll forming finally wound product 24. The upstream portion of the separated web material 22 provides for the leading edge of the web material 22 yet to be processed.
Referring again to the drawings,
The web material 22 can be transported and/or assisted by the exemplary web winding system 15 into winding contact with at least one winding spindle 28. In a preferred embodiment, a plurality of winding spindles 28 are disposed upon a winding turret 40 indexable about a center shaft, thereby defining winding turret axis of rotation 42. The winding turret 40 is preferably indexable or movable about winding turret axis of rotation 42 through an endless series of index positions. For example, a first winding spindle 44 can be located in what may conveniently be called an initial transfer position, and a second winding spindle 46 can be located in what may conveniently be called a final wind position. In any regard, the winding turret 40 is indexable about winding turret axis of rotation 42 from a first index position to a second index position. Thus, the first winding spindle 44 is moved from the initial transfer position into the final wind position. Such indexable movement of the first winding spindle 44 disposed upon winding turret 40 about winding turret axis of rotation 42 may comprise a plurality of discrete, defined positions or a continuous, non-discrete sequence of positions. However, it should be appreciated that contact roll 30 can be brought into proximate contact with winding spindle 28 by any means known to one of skill in the art. Exemplary but non-limiting turrets suitable for use with the present invention (including “continuous motion” turrets) are disclosed in U.S. Pat. Nos. 5,660,350; 5,667,162; 5,690,297; 5,732,901; 5,810,282; 5,899,404; 5,913,490; 6,142,407; and 6,354,530. As will also be appreciated by one of skill in the art, the so-called “open-loop” turret systems would also be suitable for use as a support for the disposition and movement of winding spindles 28 used in accordance with the present invention. An exemplary, but non-limiting, “open-loop” turret system is disclosed in International Publication No. WO 03/074398.
If so desired by the practitioner, the contact roll 30 of the present invention may be provided with a relieved surface. In such an embodiment, the relieved portions can be provided as a pattern disposed upon or within the material comprising contact roll 30. Such a pattern may be disposed upon or otherwise associated with contact roll 30 by laser engraving, mechanical implantation, polymeric curing, or the like. In an exemplary but non-limiting embodiment, such a pattern, relief, or otherwise may correspond to any indicia, embossments, topography pattern, adhesive, combinations thereof, and the like that are disposed upon or disposed within web material 22. It is believed that such an exemplary pattern associated with a contact roll 30 may be registered with respect to any direction or directions of the web material 22, particularly the machine and/or cross-machine directions of web material 22. Such a pattern can be associated with a contact roll 30 and can be provided relative to any indicia, embossments, topography pattern, combinations thereof, or the like associated with web material 22 by any means known to one of skill in the art. Such an embodiment may be useful in preserving desirable features in the web material 22, such as embossments, or may provide a desired contact force, such as for improved bonding force in discrete and/or desired areas of a two-ply or other multiple-ply product comprising adhesive for joining one ply to another. Similarly, the contact roll 30 can be provided with embossments and/or any other type of topographical pattern corresponding to the portions of a multi-ply type of web material 22 that may have an adhesive or other bonding formulation or structure disposed between the plies forming such a web material 22 structure. A contact roll 30 provided with such embossments and/or any other type of topographical disposed thereon can provide for better adhesion and/or bonding of the plies forming a multi-ply web material 22 by providing additional pressure to the regions sought to be so bonded as would be known to one of skill in the art. Without desiring to be bound by theory, it is believed that such increased bonding can be useful for the prevention of so-called “skinned” rolls when the plies of the multiple ply finally wound product 24 separate during dispensing by the consumer. This is known to those of skill in the art as an undesirable quality defect.
In a preferred embodiment of the present invention, the contact roll 30 is driven at a surface speed that corresponds to the speed of the incoming web material 22. A positioning device (not shown), such as linear actuators, servo motors, cams, links, and the like, known by those of skill in the art as useful to provide such a result, can be provided for control of the position of the longitudinal axis of contact roll 30 relative to the longitudinal axis of a given winding spindle 28. Such a positioning device (not shown) associated with a contact roll 30 is preferably capable of moving the contact roll 30 in any direction, including, but not limited to, the machine direction, the cross-machine direction, the Z-direction, or any combination thereof. In a preferred embodiment, the movement of contact roll 30 is generally parallel to the Z-direction relative to web material 22, as the web material 22 is in contacting engagement with a winding spindle 28. It is believed that in this way the position of the contact roll 30, when combined with the known diameter growth of the log associated with first winding spindle 44, can provide the required contact, clearance, and/or pressure between the contact roll and the log associated with first winding spindle 44 having web material 22 being disposed thereon. However, it should be realized that the contact roll 30 can be provided with movement with respect to any direction relative to its longitudinal axis in virtually any direction required to provide the required contact or clearance between the contact roll 30 and the log associated with first winding spindle 44. Likewise, the contact roll 30 can have virtually any numbers of axes (i.e., at least one) associated thereto, as required, in order to provide the required contact or clearance between the contact roll 30 and the log associated with first winding spindle 44 as web material 22 passes therebetween.
If contact between the contact roll 30 through web material 22 to the log associated with first winding spindle 44 is desired, the position of a respective contact roll 30 along an exemplary axis A and/or B can be controlled to a known position in order to provide the desired contact or clearance between the respective contact roll 30 and the respective log associated with the first winding spindle 44 throughout the entire wind, if required. Maintaining a desired contact or clearance throughout the entire wind may be particularly advantageous when winding products having higher densities. Maintaining contact throughout the wind in such an instance is believed to facilitate compaction of all layers of web material 22 within the finally wound product 24, thereby providing maximum potential density. Maintaining contact throughout the entire wind is also believed to provide product consistency when the web material 22 comprises a structure that is affected by contact force against the contact roll 30. By way of example, embossed areas disposed upon a web material 22 may have a different appearance or thickness in a region contacted by the contact roll 30 compared to an area of contact roll 30 not so contacted.
Alternatively, the position of contact roll 30 can be positioned along any of exemplary axes A, B, or any other desired axes, respectively, in order to regulate the contact force between the contact roll 30 and the respective log associated with either of first or second winding spindles 44, 46. By way of example, in order to provide a low density product roll design upon a finally wound product 24, there may be minimal or even no contact between the respective contact roll 30 and the log associated with first winding spindle 44. For medium density product roll designs in a finally wound product 24, there may be moderate contact or force between the respective contact roll 30 and the log associated with first winding spindle 44. For providing high density product roll designs in a finally wound product 24, there may be relatively high contact or force between the respective contact roll 30 and the log associated with first winding spindle 44. In any regard, it is preferred that the rotational speed of the winding spindles 28 be controlled in order to decelerate at a rate that maintains the same winding surface speed or desired speed differential as the diameter of the log associated with first winding spindle 44 increases.
Alternatively, the product density of a finally wound product 24 can be adjusted by adjusting the surface speed of the contact roll 30 and/or the surface speed of the respective log associated with first winding spindle 44. Without desiring to be bound by theory, it is believed that providing such a speed differential between the surface speed of the contact roll 30 and/or the surface speed of the log associated with first winding spindle 44 can vary the tension present in the web material 22 forming finally wound product 24. By way of non-limiting example, in order to provide a low density finally wound product 24, there may be a minimal or even no speed differential between the surface speed of the contact roll 30 and/or the surface speed of the log associated with first winding spindle 44. However, if a high density finally wound product 24 is desired, there may be relatively high speed differential or bias between the surface speed of the contact roll and/or the surface speed of the log associated with first winding spindle 44. In any regard, the surface speeds of the contact roll 30 and/or the log associated with first winding spindle 44 can be controlled jointly or severally in order to provide a finally wound product 24 having the desired wind profile.
As shown in
A perforation roll 32, anvil, or other non-contact perforation device known to those of skill in the art can be adapted to provide lines of perforations extending along the cross-machine direction of the web material 22. Adjacent lines of perforations are preferably spaced apart at a predetermined distance along the length of the web material 22 to provide individual sheets of web material 22 that are joined together at the perforations. The sheet length of the individual sheets of web material 22 is the distance between adjacent lines of perforations.
Once the desired number of sheets of web material 22 has been wound onto a log associated with first winding spindle 44 in accordance with the present invention, a web separator 66 can be utilized in order to provide separation of adjacent sheets of perforated web material 22. In the preferred embodiment, as discussed supra, the web separator 66 is provided as a rotary unit comprising a bed roll 36 and chop-off roll 38 that cooperatively engage web material 22 in a position intermediate to bed roll 36 and chop-off roll 38. In such a preferred embodiment, the web separator 66 intermittently and/or periodically contactingly engages the web material 22 disposed therebetween. The elements comprising such a semi-continuous web separator 66, either individually or collectively, can be provided with momentary periods of acceleration or deceleration. As such, the surfaces comprising the bed roll 36 and chop-off roll 38 preferably move along a circular path which has an axis coincident with the axis of rotation. Each element of the web separator 66 is almost tangent to, or makes a slight interference with, the surface of the opposing element of the web separator 66.
Once the desired number of sheets of web material 22 have been wound onto the log associated with first winding spindle 44, the web separator 66 is moved (i.e., preferably rotated) into a position which facilitates the formation of a nip between the opposing elements (i.e., the bed roll 36 and chop-off roll 38) associated with the web separator 66. Such a nip may comprise the surfaces of the bed roll 36 and chop-off roll 38 having aforementioned blades as well as rollers, pressers, or pads cooperatively associated with the bed roll 36 and chop-off roll 38 associated with the web separator 66. The movement of the bed roll 36 and chop-off roll 38 comprising the web separator 66 is preferably timed so that the web separator 66 nips the web material 22 disposed between the bed roll 36 and chop-off roll 38 when the perforation at the trailing end of the last desired sheet for the log associated with first winding spindle 44 is located between the bed roll 36 and chop-off roll 38 comprising the web separator 66.
The web material 22 disposed upstream of the nip formed between the bed roll 36 and chop-off roll 38 comprising web separator 66 is then transferred to a new winding spindle 18 which has had an adhesive disposed thereon to form second winding spindle 46. In a preferred embodiment, a core is disposed upon the new winding spindle 18 that forms second winding spindle 46 and is held securely thereto. The winding turret 40, comprising the winding spindles 18, moves the first winding spindle 44 to the finish wind position, either intermittently or continuously, and the winding cycle is repeated. After the wind has been completed, the finally wound product 24 is removed from the first winding spindle 44 disposed upon turret 40 and a new core is preferably disposed upon the now vacant winding spindle 18. Adhesive can then be applied to the new core prior to the web material 22 transfer. The winding sequence is then repeated as required.
As described previously, a preferred embodiment of the present invention includes winding the web material 22 on hollow cores for easy roll mounting and dispensing by the consumer. Additionally, the winder 20 of the instant invention provides for adjustable sheet length capability in order to provide format flexibility and sheet count control in increments of one for such format flexibility.
Further, one of skill in the art could provide the winding spindles 18 and/or contact rolls 30 with a speed profile that can allow for an enhanced winding capability. Such enhanced winding capability may be useful or even preferable for low density substrates. Additionally, disposing web material 22 between the first winding spindle 44 and a corresponding and engaged contact roll 30 forming cooperative rollers 26 can provide for an adjustable contact position and/or force upon winding spindle 28 and the web material 22 at the periphery of the log associated with first winding spindle 44. Providing first winding spindle 44 with an adjustable rotational speed can provide for the ability to apply a force at a point after the web material 22 is disposed upon first winding spindle 44. This process can provide for a finally wound product 24 having the desired wind profile.
For example, finally wound product 24 may be produced as a web material 22 having a perforated sheet length of 250 mm, a 100-sheet count, a finished roll diameter of 130 mm, and be wound upon a core having an outer diameter of 40 mm. Using this information, the theoretical average radial thickness for each layer of web material 22 comprising finally wound product 24 can be calculated to be about 480 μm. In such an exemplary embodiment, the web material 22 may be provided with an initial (i.e., untensioned thickness of 750 μm as web material 22 enters the winding area of winder 20. In order to provide for the above-described finally wound product 24, if no contact exists between the log associated with a winding spindle 28 and the corresponding contact roll 30, the web material 22 must be compressed from the initial thickness of 750 μm to the required theoretical target thickness of 480 μm by only the tension exerted by the winding spindle 28 speed on the incoming web material 22. Without desiring to be bound by theory, the calculated tension required to decrease the thickness of web material 22 from an initial 750 μm thickness to the required 480 μm thickness is about 50 g per linear centimeter. However, one of skill in the art will appreciate that the web material 22 may separate uncontrollably at the perforations disposed within web material 22 when web material 22 is subject to such a tension (i.e., nominally greater than 350 g per linear centimeter). Such uncontrolled separations can produce an unacceptable finally wound product 24 and potentially result in line/production stoppages.
Additionally, the winder 20, as disclosed supra, may be utilized to provide supplemental compression of the web material 22 being wound upon a winding spindle 28 to produce finally wound product 24. For example, a contact roll 30 may be loaded against the log associated with the corresponding winding spindle 18 by moving the position of the contact roll 30 along exemplary axes A and/or B relative to a winding spindle 18 in order to achieve the desired finally wound product 24. For example, a contact roll 30 may be loaded against a log disposed upon a corresponding winding spindle 28 with a force of 100 g per linear centimeter. By calculation, it is believed that such a force may decrease the thickness of the web material 22 from a thickness of 750 μm to a thickness of 500 μm. The calculated required winding tension to further decrease the thickness of web material 22 from a thickness of 500 μm to the required thickness of 480 μm may be provided with as little as 40 g per linear centimeter. This required tension level is well below the known and assumed perforation separation level of 350 g per linear centimeter, thereby allowing reliable production of the desired finally wound product 24.
Additionally, one of skill in the art will understand that the winder 20 disclosed herein can provide contact with the log associated with the first winding spindle 34 throughout the entirety of a wind cycle. Thus, a finally wound product 24 can be provided with heretofore unrealized winding uniformity throughout the entire finally wound product 24. Further, one of skill in the art will realize that providing winding spindles 28 in a turret system 40 moving in a closed path can provide for continuous winding and removal of finally wound product 24 without the need to interrupt the turret system 40 to load and unload winding spindles 28 or even the cores disposed upon winding spindles 28 from a moving turret system 40 mechanism.
As used herein, a “machine degree” is equivalent to 1/360 of a complete cycle. With regard to the winder 20 described herein, the 360 machine degrees is defined as a complete rewind cycle; that is, from a first identified index position (such as an initial transfer position or a final wind position) to the next identical and succeeding index position (such as the subsequent or second identical initial transfer position or the subsequent or second identical final wind position).
Referring to
Concurrent with the separation of web material 22 at the identified perforation, the contact roll 30 is movable along an exemplary axis A, as well as a machine direction axis B. In a preferred embodiment, each winding spindle 18 is provided with a core having an adhesive disposed upon the surface thereof to facilitate attachment of the leading edge of the web material 22 to the respective winding spindle 28. Further, the remaining web material 22 attached to winding spindle 28 forming old log 54 continues to be disposed thereon. It should be realized that contact roll 30 supporting web material 22 can be movable about one or a plurality of exemplary axis (shown as A and B) in order to provide for a desired pressure to be exerted upon new log 56 having web material 22 disposed thereon. It is in this manner that old log 54 and new log 56 can be provided with a desired wind profile during the entirety of the winding process.
It should be realized that the position and/or loading force of the contact roll 30 upon any winding spindle 18 can be adjusted such that contact roll 30 maintains the desired contact force or position relative to the winding spindle 18 at all points during the winding cycle. Additionally, the contact roll 30 is initially driven at a surface speed that corresponds to the speed of the incoming web material 22 and the surface speed of the first winding spindle 44. In a non-limiting embodiment, positioning devices, such as linear actuators, can control the position of the contact roll 30. In any regard, the position of the contact roll 30, combined with the known diameter growth of the desired winding log, can determine the contact or clearance between the contact roll 30 and the winding log. If contact is desired, such contact may be controlled to a known position or interference or, alternatively, by regulating the contact force between the contact roll and each respective winding logs 52, 54. By way of non-limiting example, if low density product roll designs are desired, there may be no contact between contact roll 30 and the respective winding logs 54, 56. By further example, if medium density product roll designs are desired, there may be moderate contact or force between the contact roll 30 and the respective winding logs 54, 56. Yet further, if high density product roll designs are desired, there may be relatively high contact or force provided between the contact roll 30 and the respective winding logs 54, 56.
In any regard, it is preferred that the contact roll 30 provided herein contact the respective winding logs 54, 56 at a point other than the tangent point of the incoming web material 22. In all cases, the rotational speed of the winding spindle 28 is controlled to decelerate at a rate that maintains the same winding surface speed or desired differential as the winding log diameter increases. It is believed that such profiled mandrel drive systems are well known to those of skill in the art.
In a preferred embodiment, the position and/or force applied by all contact rolls 30 upon the respective winding spindle 28 is preferably independently adjustable. The position of each contact roll 30 can be adjusted such that each contact roll 30 maintains the desired contact force or position relative to the respective winding log at all points during the winding cycle. To ensure a reliable web transfer to a new core, it is preferred that each contact roll 30 is initially driven at a surface speed that corresponds to the speed of the incoming web and the surface speed of the new core. Positioning devices, such as linear actuators and the like, can control the position of each contact roll 30. The position of each contact roll 30 combined with the known diameter growth of the respective winding log can determine the contact or clearance between each of the respective contact rolls 30 and the respective winding logs. If contact is desired, such contact can be controlled to a known position or interference or, alternatively, by regulating the contact force between the respective contact roll 30 and the respective winding log. Due to their position (disposed upon turret 40), each respective contact roll 30 cannot contact the respective winding log at the point where the incoming web material 22 first contacts the winding log. In other words, the respective contact roll 30 contacts the associated winding log at a point downstream of the point at which the web material 12 first contacts that particular winding log. It is believed that the application of a compressive force upon the winding log by the respective contact roll 30 can still increase the density of the finally wound product 24 disposed upon winding spindle 18.
As shown in
All documents cited in the Detailed Description of the Invention are, in relevant part, incorporated herein by reference; the citation of any document is not to be construed as an admission that it is prior art with respect to the present invention. To the extent that any meaning or definition of a term in this written document conflicts with any meaning or definition of the term in a document incorporated by reference, the meaning or definition assigned to the term in this written document shall govern.
The dimensions and values disclosed herein are not to be understood as being strictly limited to the exact numerical values recited. Instead, unless otherwise specified, each such dimension is intended to mean both the recited value and a functionally equivalent range surrounding that value. For example, a dimension disclosed as “40 mm” is intended to mean “about 40 mm”.
While particular embodiments of the present invention have been illustrated and described, it would be obvious to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the invention. It is therefore intended to cover in the appended claims all such changes and modifications that are within the scope of this invention.
