LEADING EDGE DEVICE FOR A SURFACE WINDER

Abstract

A leading edge device for incorporation into an introductory portion a concave cradle is disclosed d. The concave cradle is associated with an upper winding roller of a surface winder to form a winding cradle for winding a web material having a velocity, v, around a core having a radius, R, inserted therein to obtain a log. The leading edge device has a surface having a texture provided thereto for contacting the core.

Claims

1. An improvement to a surface winder for winding a web material around a core having a radius, R, to obtain a log, the surface winder comprising a glue applicator for dispensing glue onto said core, a core inserter for transporting and inserting said core provided with said glue disposed thereon into a winding cradle defined at a top by an upper winding roller, supplied from above with said web material directed towards said winding cradle at a velocity, v, and at a bottom by a concave cradle associated downstream to a lower winding roller, said surface winder comprising a third oscillating roller arranged above said lower winding roller, said upper winding roller, said lower winding roller, and said third oscillating roller each having a respective axes parallel to each other and perpendicular to the feeding direction of said web material and cooperating with each other downstream of said winding cradle in order to wind said web material around said core to obtain said log, said concave cradle comprising an introductory portion, the improvement comprising: wherein said introductory portion of said concave cradle comprises a leading edge device, said leading edge device having a surface for contacting said core, said surface having a texture provided thereto.

2. The improvement to a surface winder of claim 1 wherein said surface causes said core to rotate at an angular velocity, ω, wherein v=Rω.

3. The improvement to a surface winder of claim 1 wherein said core contacts said leading edge device concurrently with contacting said web material in contacting engagement with said upper winding roller.

4. The improvement to a surface winder of claim 1 wherein said texture is a plurality of protuberances disposed upon said surface of said leading edge device, said core contacting said protuberances when disposed between said leading edge device and said web material in contacting engagement with said upper winding roller.

5. The improvement to a surface winder of claim 4 wherein each protuberance of said plurality of protuberances disposed upon said surface of said leading edge device are collectively elongate.

6. The improvement to a surface winder of claim 4 wherein each protuberance of said plurality of protuberances disposed upon said surface of said leading edge device are disposed randomly upon said surface of said leading edge.

7. The improvement to a surface winder of claim 4 wherein each protuberance of said plurality of protuberances disposed upon said surface of said leading edge device are disposed in a pattern upon said surface of said leading edge.

8. The improvement to a surface winder of claim 4 wherein each protuberance of said plurality of protuberances disposed upon said surface of said leading edge device are provided with a geometry, said geometry of each of said protuberances reducing slippage between said core and said surface of said leading edge device.

9. The improvement to a surface winder of claim 8 wherein said geometry is selected from the group consisting of pins, polyhedrons, and combinations thereof.

10. The improvement to a surface winder of claim 1 wherein said texture is a plurality of linear sections disposed upon said surface of said leading edge device, said core contacting said linear sections when disposed between said leading edge device and said web material in contacting engagement with said upper winding roller.

11. The improvement to a surface winder of claim 1 wherein said texture is a plurality of linear sections disposed within said surface of said leading edge device, said core contacting said linear sections when disposed between said leading edge device and said web material in contacting engagement with said upper winding roller.

12. The improvement to a surface winder of claim 1 wherein said texture is a plurality of grooves disposed upon said surface of said leading edge device, said core contacting said grooves when disposed between said leading edge device and said web material in contacting engagement with said upper winding roller.

13. A leading edge device for incorporation into an introductory portion a concave cradle, said concave cradle being associated with an upper winding roller of a surface winder to form a winding cradle for winding a web material having a velocity, v, around a core having a radius, R, inserted therein to obtain a log, said leading edge device having a surface for contacting said core, said surface having a texture provided thereto.

14. The leading edge device of claim 13 wherein said surface causes said core to rotate at an angular velocity, ω, wherein v=Rω.

15. The leading edge device of claim 13 wherein said core contacts said leading edge device concurrently with contacting said web material.

16. The leading edge device of claim 13 wherein said texture is a plurality of protuberances disposed upon said surface of said leading edge device, said core contacting said protuberances when disposed between said leading edge device and said web material in contacting engagement with said upper winding roller.

17. The leading edge device of claim 16 wherein each protuberance of said plurality of protuberances disposed upon said surface of said leading edge device are provided with a geometry, said geometry of each of said protuberances reducing slippage between said core and said surface of said leading edge device.

18. The leading edge device of claim 13 wherein said texture is a plurality of linear sections disposed upon said surface of said leading edge device, said core contacting said linear sections when disposed between said leading edge device and said web material in contacting engagement with said upper winding roller.

19. The leading edge device of claim 13 wherein said texture is a plurality of linear sections disposed within said surface of said leading edge device, said core contacting said linear sections when disposed between said leading edge device and said web material in contacting engagement with said upper winding roller.

20. The leading edge device of claim 13 wherein said texture is a plurality of grooves disposed upon said surface of said leading edge device, said core contacting said grooves when disposed between said leading edge device and said web material in contacting engagement with said upper winding roller.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] FIG. 1 is a cross-sectional view of an exemplary surface rewinding machine;

[0017] FIG. 2 is a cross sectional view of an exemplary prior art surface winder including a core in-feed apparatus showing an initial stage of the transport of a winding core that has glue disposed upon a surface thereof;

[0018] FIG. 3 is a cross sectional view of an exemplary prior art surface winder including a core in-feed apparatus showing a second stage of the transport of a winding core that has glue disposed upon a surface thereof;

[0019] FIG. 4 is a cross sectional view of an exemplary prior art surface winder including a core in-feed apparatus showing a third stage of the transport of a winding core that has glue disposed upon a surface thereof;

[0020] FIG. 5 is a cross sectional view of an exemplary prior art surface winder including a core in-feed apparatus showing a fourth stage of the transport of a winding core that has glue disposed upon a surface thereof where the winding core is presented at the introductory portion of a winding cradle;

[0021] FIG. 6 is a cross sectional view of an exemplary prior art surface winder having a winding core disposed at the introductory portion of a winding cradle;

[0022] FIG. 7 is a perspective view of an exemplary prior art introductory portion of the winding cradle of the region labeled 2 in FIG. 1 having a smooth surface;

[0023] FIG. 8 is a cross-sectional view of an exemplary surface prior art winding machine showing a core ‘slipping’ through the introductory portion of the surface rewinding machine while disposed between the upper winding roll and the winding cradle due to the introductory portion of the winding cradle of the region labeled 2 in FIG. 1 having a smooth surface;

[0024] FIG. 9 is a perspective view of an exemplary leading edge device having a surface texture applied thereto in the form of pins;

[0025] FIG. 10 is a perspective view of an exemplary leading edge device having a surface texture applied thereto in the form of linear sectioned grooves; and,

[0026] FIG. 11 is a perspective view of an exemplary leading edge device having a surface texture applied thereto in the form of elongate linear grooves.

DETAILED DESCRIPTION

[0027] An exemplary embodiment of a prior art rewinder is shown in FIG. 1. As presented, FIG. 1 shows the main members of the rewinder, and in particular the members intended to feed the winding cores A and the winding rollers.

[0028] The winding head of the exemplary prior art rewinder is generically indicated with 1. In this exemplary embodiment, the winding head of the rewinding machine comprises a first winding roller 3 (also referred to herein as upper winding roll 3) with a rotation axis 3A, a second winding roller 5 (also referred to herein as lower winding roll 5) rotating about a rotation axis 5A and a third winding roller 7 (also referred to herein as rider roll 7) rotating about a third rotation axis 7A. A nip 11 is defined between the two winding rollers 3 and 5 for passage of the web material, having a speed, v, which can be equal to the surface speed of upper winding roll 3, wound about a core A.

[0029] In some embodiments the axis 3A of the first winding roller 3 is fixed with respect to a load bearing structure (not shown) of the rewinder. In other embodiments the axis 3A can be moving with respect to the load bearing structure (not shown).

[0030] In some embodiments the axis 5A of the second winding roller 5 is movable. In some embodiments the axis 5A can be moved to produce logs with a winding core A. In other embodiments, the rotation axis 5A of the second winding roller 5 can be movable in a controlled manner also during each winding cycle of logs upon a core A having a variable diameter. Ideally, the axis 5A of the second winding roller 5 can be movable to adapt the machine to winding cores A or mandrels having different diameters. In any regard, the first winding roller 3 can have a moving axis 3A for the same reasons indicated above. Further, both the winding rollers 3 and 5 can be movable and adjustable.

[0031] The third winding roller 7 is advantageously carried, for example, by a pair of arms 9 pivoting with a reciprocating movement according to the double arrow f9 about a pivoting axis 9A. The movement according to the double arrow f9 enables the third winding roller 7 to move toward or away from the first winding roller 3 and second winding roller 5 according to the diameter of the log L during the step of formation inside the winding cradle defined by the three winding rollers 3, 5 and 7.

[0032] The exemplary prior art rewinding machine 1 can be provided with a concave cradle 41. The concave cradle 41 is in actual fact preferably formed by a series of mutually parallel shaped plates, only one of which is visible in the drawing and the others being superimposed thereon. The various shaped plates all have a concave edge forming a concave surface for rolling of the winding cores.

[0033] The winding cores A are fed along a feeder 47. Single winding cores A can be picked up by a core inserter 49 after a longitudinal line of glue has been applied thereto by a glue applicator 51. The machine in this arrangement has substantially the same structure and operation as that described in U.S. Pat. No. 5,979,818 and therefore the operating cycle will not be described in detail.

[0034] As shown in FIGS. 2-6, cam housing 34 of core inserter 10 can be provided with a cam disposed within cam housing 34 that defines the orbital motion of movable finger 28 attached thereto about the longitudinal axis of core inserter 10. The cam can be provided with any desired profile required by the manufacturing operation to provide the desired motion about the longitudinal axis 38.

[0035] In this regard, movable finger 28 can emanate from a centroid of cam housing 34 in a manner that causes cam housing 34 to orbit about the longitudinal axis 38 of cam-controlled core inserter 10. As cam housing 34 orbits about the longitudinal axis 38 while disposed in contacting and moveable engagement with cam housing 34, cam housing 34 can define the motion of movable finger 28 relative to the longitudinal axis 38, fixed finger 22, and winding core A. Without desiring to be bound by theory, it is believed that by providing a cam housing 34 system to control the movement of movable finger 28 of cam-controlled core inserter 10 can provide a more reliable and consistent contact and release system for the insertion of a winding core A into the introductory portion 12 of winding cradle 13.

[0036] As shown in FIGS. 3-6, as the fixed fingers 22 of core inserter 10 approach the introductory portion 12 of winding cradle 13, winding core A remains in contacting engagement with fixed finger 22 and movable finger 28 of cam-controlled core inserter 10 as the winding core A approaches the introductory portion 12 of winding cradle 13. Clearly, the core inserter 10 of the present disclosure is provides more certainty relative to the insertion of a winding core A into the introductory portion 12 of winding cradle 13.

[0037] Returning again to FIG. 1, the moving member 21 can be used to sever the web material N, but winding starts on the central core A and the member 21 does not perform any function in relation to this action, except for an optional effect of accompanying the leading edge toward the new winding core A that is inserted into the channel formed between the winding roller 3 and the cradle 41 upstream (with respect to the direction of feed of the web material N) of the moving member 21.

[0038] Interaction between the concave cradle 41 and the moving member 21 is permitted by the fact that the former has a comb shaped structure formed by a plurality of parallel plates. In this way, the pads 23 of the moving member 21 can pass between adjacent plates and enter the feed channel of the winding cores A formed between the concave surface 41A of the cradle 41 and the cylindrical surface 3B of the winding roller 3.

[0039] The concave cradle 41 can be supported rotating about the rotation axis 21C of the moving member 21. The moving member passes from an idle position to an operating position by pivoting about the rotation axis 21C. Pivoting can be controlled by a piston-cylinder actuator.

[0040] Moving member 21 can be provided with a reciprocating oscillatory or rotary movement around said axis. The moving member 21 rotates in clockwise direction to come into contact with the web material N and pinch it against the cylindrical surface of the winding roller 3 and perform severing of the web material N.

[0041] As mentioned previously, single winding cores A are picked up by a core inserter 49 after a longitudinal line of glue has been applied thereto by a glue applicator 51. The core inserter 49 translates the winding core A having glue disposed thereon to a point of entry into the introductory portion 12 of the surface rewinding machine disposed between the upper winding roll 3 having a web material N disposed about at least a portion thereof and the concave cradle 41. The region disposed between concave cradle 41 and upper winding roll 3 is referred to herein as winding cradle 13. The region disposed between leading edge device 14 and upper winding roll 3 forms the introductory portion 12 of winding cradle 13. While it is possible for web material N to have a velocity, v, that is different from the surface velocity of upper winding roll 3 about its longitudinal axis 3A, for purposes of discussion herein, it can be presumed that the velocity, v, of web material N is the same as the surface velocity of upper winding roll 3 about its longitudinal axis 3A.

[0042] As shown in FIG. 7, a typical leading edge device 14 is provided with a surface 15 that can be considered to have a finish texture 50 that provides a generally smooth and polished finish. Leading edge device 14 is typically affixed to the concave cradle 41.

[0043] As shown in FIG. 8 however, and as discussed supra, a leading edge device 14 provided with a generally smooth and polished finished surface can actually facilitate the sliding (e.g., purely translational movement and little or no rotational movement) of a winding core A disposed within the introductory portion 12 of winding cradle 13. Without desiring to be bound by theory, it is believed that winding core A initially slips, and does not immediately assume a rotational surface speed as it first contacts surface 15 of leading edge device 14 and the moving web material N having a velocity, v, contacting the surface of upper winding roll 3.

[0044] One of skill in the art will understand that when rolling of winding core A happens without slipping, the point of contact of winding core A has zero linear velocity relative to the surface 15 of leading edge device 14. When slipping (with or without rolling) of the winding core A occurs, the point of contact of winding core A with the surface 15 of leading edge device 14 has a non-zero linear velocity relative to the surface 15 of leading edge device 14. As the winding core A essentially (or effectively) slides along (or upon) the surface 15 of leading edge device 14, kinetic friction, f, eventually reduces the linear (e.g., non-rotational) velocity of winding core A relative to the surface 15 of leading edge device 14. This frictional force, f, also causes the winding core A to start rotating about its center of mass (cm). The linear velocity along the surface 15 of the leading edge device 14 of the winding core A decreases and the angular velocity, w, of winding core A increases until the non-slip condition v.sub.cm=Rω is met. Then winding core A effectively rolls upon the surface 15 of leading edge device 14 about its center of mass without (or with reduced) slipping.

[0045] In other purely mechanical terms, the linear velocity, v, of the winding core A must always equal the rate of rotation, ω, of the winding core A multiplied by the radius, R, of the winding core A from the center of rotation to the point of contact of winding core A with upper winding roll 3. If the magnitude of the linear velocity at the edge of the rotating winding core A does not equal the magnitude of the linear velocity of the center of rotation of the rotating winding core A, then there must be slipping at the point of contact of winding core A with upper winding roll 3 or the surface 15 of leading edge device 14. This results in the linear, non-rotating (i.e., translational) movement of winding core A relative to the surface 15 of leading edge device 14 because the center of rotation/mass of the winding core A must move faster than the rotation of upper winding roll 3 can move it. In other words, when winding core A experiences pure translational motion, all of its points move with the same velocity as the center of mass (e.g., in the same direction and with the same speed (v=v.sub.cm). The force of friction, f, from the surface 15 of leading edge device 14 is the only force acting upon the surface of winding core A to cause the winding core A to reduce the translational velocity, v, and increase the rotational velocity of winding core A to match the surface speed of upper winding roll 3 and web material N in contacting engagement therewith (e.g., in the rewinder described herein—also having a velocity v).

[0046] Mathematically stated, at the point of insertion of the winding core A into the introductory portion 12 of winding cradle 13 slipping and rolling forward provides v.sub.cm<Rω. Thus, the path of winding core A through the introductory portion 12 of winding cradle 13 forms a prolate (contracted) cycloid because it is traced out to points on the surface of the generating circle that is slipping while rolling with a velocity of v.sub.cm<Rω.

[0047] Therefore, one of skill in the art would understand that it can be desirable to provide the winding core A with a rotational velocity (i.e., a rolling motion) at the point of contact with upper winding roll 3 and the surface 15 of leading edge device 14. In this way, the rolling of winding core A becomes a combination of both translational and rotational motion. Thus, when the winding core A experiences pure rotational motion about its center of mass, all of its points move at right angles to the radius, R, in a plane perpendicular to the axis of rotation, so that points on opposite sides of the axis of rotation of winding core A move in opposite directions, and move with a speed proportional to radius (v=Rω), so that the center of mass does not move (since R=0) and points on the outer radius of winding core A move with speed v=Rω, and move in a circle centered on the axis of rotation (also the center of mass).

[0048] As shown in FIGS. 9-11, an exemplary leading edge device 14 can be provided with a surface 15 that has a texture 50 provided thereto. Without desiring to be bound by theory, it is believed that providing a leading edge device 14 with a finish texture 50 upon surface 15 that can reduce the slippage of a respective winding core A that will be inserted into the introductory portion 12 of winding cradle 13.

[0049] By way of non-limiting example, as shown in FIG. 9, a suitable leading edge device 14A can be provided with a surface 15A having a finish texture 50A that comprises a plurality of protuberances. Each protuberance of the plurality of protuberances can be arranged in any manner desired upon the surface 15A of leading edge device 14A required by the user in order to reduce the slippage of a respective winding core A inserted into the introductory portion 12 of winding cradle 13. For example, each protuberance of the plurality of protuberances can be randomly distributed upon the surface 15A of leading edge device 14A. Alternatively, each protuberance of the plurality of protuberances can be provided in defined patterns (as may be required by the web materials wound about the respective winding core A or by any other process parameter) that form the finish texture 50A upon the surface 15A of leading edge device 14A. For example, a finish texture 50A can be provided so that a series of protuberances of the plurality of protuberances are collectively elongate upon the surface 15A of leading edge device 14A.

[0050] Further, each protuberance can have any geometry that may be required to reduce the slippage between a respective winding core A and the surface 15A of leading edge device 14A. For example, each protuberance can be provided as a pin extending from the surface 15A of leading edge device 14A. Alternatively, each protuberance can be provided as a polyhedron having a shape that is a pyramid, a cylinder, a cone, a truncated cone, a sphere, a prism, an ellipsoid, and/or combinations thereof. Clearly, one of skill in the art will recognize that the plurality of protuberances can be provided as combinations thereof.

[0051] FIG. 10, depicts another non-limiting example of a leading edge device 14B provided with a surface 15B having a finish texture 50B that comprises a series of linear sections. The series of linear sections can be disposed upon and extend from the surface 15B of leading edge device 14B. Alternatively, the series of linear sections can be disposed upon and extend into the surface 15B of leading edge device 14B. Each series of linear sections can be disposed at any location upon the surface 15B of leading edge device 14B. Further any number of series of linear sections can be disposed at any location and/or orientation upon the surface 15B of leading edge device 14B. Additionally, linear section of a series of linear sections can be provided with any length, height, and/or depth relative to the surface 15B of leading edge device 14B.

[0052] As shown in FIG. 11, another non-limiting example of a leading edge device 14C can be provided with a surface 15C having a finish texture 50C that comprises a series of elongate grooves disposed within the surface 15C of leading edge device 14C. Alternatively, leading edge device 14C can be provided with a surface 15C having a finish texture 50C that comprises a series of elongate protuberances disposed upon the surface 15C of leading edge device 14C. Further the elongate grooves and/or protuberances can be disposed at any location, orientation, and/or distribution relative to the surface 15B of leading edge device 14B. The elongate grooves and/or protuberances can be linear, curvilinear, sinusoidal, and/or combinations thereof. The elongate grooves and/or protuberances can be used together to form a surface 15C that has both protuberances extending from the surface 15C of leading edge device 14C and grooves extending into the surface 15C of leading edge device 14C.

EXAMPLES

[0053] a. An improvement to a surface winder for winding a web material around a core having a radius, R, to obtain a log, the surface winder comprising a glue applicator for dispensing glue onto said core, a core inserter for transporting and inserting said core provided with said glue disposed thereon into a winding cradle defined at a top by an upper winding roller, supplied from above with said web material directed towards said winding cradle at a velocity, v, and at a bottom by a concave cradle associated downstream to a lower winding roller, said surface winder comprising a third oscillating roller arranged above said lower winding roller, said upper winding roller, said lower winding roller, and said third oscillating roller each having a respective axes parallel to each other and perpendicular to the feeding direction of said web material and cooperating with each other downstream of said winding cradle in order to wind said web material around said core to obtain said log, said concave cradle comprising an introductory portion, the improvement comprising: wherein said introductory portion of said concave cradle comprises a leading edge device, said leading edge device having a surface for contacting said core, said surface having a texture provided thereto. [0054] b. The improvement to a surface winder of a. wherein said surface causes said core to rotate at an angular velocity, ω, wherein v=Rω. [0055] c. The improvement to a surface winder of any of a. through b. wherein said core contacts said leading edge device concurrently with contacting said web material in contacting engagement with said upper winding roller. [0056] d. The improvement to a surface winder of any of a. through c. wherein said texture is a plurality of protuberances disposed upon said surface of said leading edge device, said core contacting said protuberances when disposed between said leading edge device and said web material in contacting engagement with said upper winding roller. [0057] e. The improvement to a surface winder of d. wherein each protuberance of said plurality of protuberances disposed upon said surface of said leading edge device are collectively elongate. [0058] f. The improvement to a surface winder of d. wherein each protuberance of said plurality of protuberances disposed upon said surface of said leading edge device are disposed randomly upon said surface of said leading edge. [0059] g. The improvement to a surface winder of d. wherein each protuberance of said plurality of protuberances disposed upon said surface of said leading edge device are disposed in a pattern upon said surface of said leading edge. [0060] h. The improvement to a surface winder of d. wherein each protuberance of said plurality of protuberances disposed upon said surface of said leading edge device are provided with a geometry, said geometry of each of said protuberances reducing slippage between said core and said surface of said leading edge device. [0061] i. The improvement to a surface winder of h. wherein said geometry is selected from the group consisting of pins, polyhedrons, and combinations thereof. [0062] j. The improvement to a surface winder of any of a. through i. wherein said texture is a plurality of linear sections disposed upon said surface of said leading edge device, said core contacting said linear sections when disposed between said leading edge device and said web material in contacting engagement with said upper winding roller. [0063] k. The improvement to a surface winder of any of a. through j. wherein said texture is a plurality of linear sections disposed within said surface of said leading edge device, said core contacting said linear sections when disposed between said leading edge device and said web material in contacting engagement with said upper winding roller. [0064] l. The improvement to a surface winder of any of a. through k. wherein said texture is a plurality of grooves disposed upon said surface of said leading edge device, said core contacting said grooves when disposed between said leading edge device and said web material in contacting engagement with said upper winding roller. [0065] m. A leading edge device for incorporation into an introductory portion a concave cradle, said concave cradle being associated with an upper winding roller of a surface winder to form a winding cradle for winding a web material having a velocity, v, around a core having a radius, R, inserted therein to obtain a log, said leading edge device having a surface for contacting said core, said surface having a texture provided thereto. [0066] n. The leading edge device of m. wherein said surface causes said core to rotate at an angular velocity, ω, wherein v=Rω. [0067] o. The leading edge device of any of m. through n. wherein said core contacts said leading edge device concurrently with contacting said web material. [0068] p. The leading edge device of any of m. through o. wherein said texture is a plurality of protuberances disposed upon said surface of said leading edge device, said core contacting said protuberances when disposed between said leading edge device and said web material in contacting engagement with said upper winding roller. [0069] q. The leading edge device of p. wherein each protuberance of said plurality of protuberances disposed upon said surface of said leading edge device are provided with a geometry, said geometry of each of said protuberances reducing slippage between said core and said surface of said leading edge device. [0070] r. The leading edge device of any of m. through q. wherein said texture is a plurality of linear sections disposed upon said surface of said leading edge device, said core contacting said linear sections when disposed between said leading edge device and said web material in contacting engagement with said upper winding roller. [0071] s. The leading edge device of any of m. through r. wherein said texture is a plurality of linear sections disposed within said surface of said leading edge device, said core contacting said linear sections when disposed between said leading edge device and said web material in contacting engagement with said upper winding roller. [0072] t. The leading edge device of any of m. through s. wherein said texture is a plurality of grooves disposed upon said surface of said leading edge device, said core contacting said grooves when disposed between said leading edge device and said web material in contacting engagement with said upper winding roller.

[0073] Any dimensions and/or values disclosed herein are not to be understood as being strictly limited to the exact dimensions and/or numerical values recited. Instead, unless otherwise specified, each such dimension and/or value is intended to mean both the recited dimension and/or value and a functionally equivalent range surrounding that dimension or value. For example, a dimension disclosed as “40 mm” is intended to mean “about 40 mm.”

[0074] 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 document conflicts with any meaning or definition of the same term in a document incorporated by reference, the meaning or definition assigned to that term in this document shall govern.

[0075] 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.