Abstract
Disclosed is a refiner filling piece for a refiner having a rotor that rotates about an axis of rotation and cooperates with a stator to mechanically treat a pulp containing cellulosic fibers. The refiner filling piece is mountable to the rotor or the stator. The refiner filling piece comprises a base and a plurality of spacer-integrated refiner bars having a bar portion and a spacer portion integrally formed with the bar portion. At least some of the spacer-integrated refiner bars have a surface coated with a variable coating. The surface having the variable coating may be the leading surface of the bar. The spacer-integrated refiner bars may be tilted bars.
Claims
1. A refiner filling piece for a refiner having a rotor that rotates about an axis of rotation and cooperates with a stator to mechanically treat a pulp containing cellulosic fibers, the refiner filling piece being mountable to the rotor or the stator, the refiner filling piece comprising: a base; a plurality of spacer-integrated refiner bars having a bar portion and a spacer portion integrally formed with the bar portion; and wherein at least some of the spacer-integrated refiner bars have a surface coated with a variable thickness coating.
2. The refiner filling piece of claim 1 wherein the variable coating has a coating thickness that varies over a bar height.
3. The refiner filling piece of claim 2 wherein the variable coating has a coating thickness that varies linearly over the bar height.
4. The refiner filling piece of claim 2 wherein the variable coating has a coating thickness that varies nonlinearly over the bar height.
5. The refiner filling piece of claim 2 wherein the variable coating begins at a point above the spacer portion thereby defining an uncoated lower portion.
6. The refiner filling piece of claim 2 wherein the spacer-integrated bar is tilted at an acute angle relative to the base.
7. The refiner filling piece of claim 2 wherein a leading surface of the spacer-integrated bar has the variable coating.
8. The refiner filling piece of claim 1 wherein the variable coating has a coating thickness that varies along a bar length.
9. The refiner filling piece of claim 8 wherein the variable coating has a coating thickness that varies linearly along the bar length.
10. The refiner filling piece of claim 8 wherein the variable coating has a coating thickness that varies nonlinearly along the bar length.
11. The refiner filling piece of claim 8 wherein the variable coating extends only partially along the bar length.
12. The refiner filling piece of claim 8 wherein the spacer-integrated bar is tilted at an acute angle relative to the base.
13. The refiner filling piece of claim 8 wherein a leading surface of the spacer-integrated bar has the variable coating.
14. A refiner comprising: a housing; a stator supported within the housing; a rotor that rotates about an axis of rotation and cooperating with the stator to mechanically treat a pulp containing cellulosic fibers; a first refiner filling piece fastened to the rotor; and a second refiner filling piece fastened to the stator; wherein each of the first and second refining filling piece comprises: a base; a plurality of spacer-integrated refiner bars having a bar portion and a spacer portion integrally formed with the bar portion; and wherein at least some of the spacer-integrated refiner bars have a surface coated with a variable thickness coating.
15. The refiner of claim 14 wherein the variable coating has a coating thickness that varies over a bar height.
16. The refiner of claim 15 wherein the variable coating begins at a point above the spacer portion.
17. The refiner of claim 15 wherein the spacer-integrated bar is tilted at an acute angle relative to the base.
18. The refiner of claim 14 wherein the variable coating has a coating thickness that varies along a bar length.
19. The refiner of claim 18 wherein the variable coating begins at a point above the spacer portion.
20. The refiner of claim 18 wherein the spacer-integrated bar is tilted at an acute angle relative to the base.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] Further features and advantages of the present technology will become apparent from the following detailed description, taken in combination with the appended drawings, in which:
[0011] FIG. 1 is a perspective view of a refiner having a rotor and stator in accordance with an embodiment of the present invention showing the replacement of a refiner filling piece on the stator.
[0012] FIG. 2 is another perspective view of the refiner of FIG. 1 showing the replacement of a refiner filling piece on the rotor.
[0013] FIG. 2A is a plan view of four refiner filling pieces shaped as four arcuate segments as one example of segmented filling pieces for a disc-type refiner.
[0014] FIG. 3 is a cross-sectional view of a refiner filling piece having a variable coating on a leading surface of the bars.
[0015] FIG. 4 is a cross-sectional view of a refiner filling piece having a variable coating on a leading surface of the bars.
[0016] FIG. 5 is a cross-sectional view of a refiner filling piece having a variable coating on a leading surface of the bars.
[0017] FIG. 6 is a cross-sectional view of a refiner filling piece having a variable coating on a leading surface and a thinner variable coating on the trailing surface.
[0018] FIG. 7 is a cross-sectional view of a refiner filling piece having a variable coating on a leading surface and a thinner variable coating on the trailing surface.
[0019] FIG. 8 is a cross-sectional view of a refiner filling piece having a variable coating on a leading surface and a thinner variable coating on the trailing surface.
[0020] FIG. 9 is a top view of a refiner filling piece in accordance with one embodiment of the invention in which the variable coating varies linearly along a bar length on the leading surface.
[0021] FIG. 10 is a top view of a refiner filling piece in accordance with another embodiment of the invention in which the variable coating varies linearly along a bar length on the leading surface and a thinner variable coating varies along the bar length on the trailing surface.
[0022] FIG. 11 depicts a conical refiner filling piece to which a variable coating may be applied in accordance with another embodiment of the invention.
[0023] FIG. 12 is a cross-sectional view of a refiner filling piece having a variable coating on a unitary or integrated bar and spacer in accordance with another embodiment of the invention in which the variable coating is a linearly variable coating that begins at a point above the spacer portion of the unitary or integrated bar and spacer.
[0024] FIG. 13 is a cross-sectional view of a refiner filling piece having a variable coating on a unitary or integrated bar and spacer in accordance with another embodiment of the invention in which the variable coating is a linearly variable coating that entirely covers the leading surface.
[0025] FIG. 14 is a cross-sectional view of a refiner filling piece having a variable coating on a unitary or integrated bar and spacer in accordance with another embodiment of the invention in which the variable coating is a nonlinearly variable coating that begins at a point above the spacer portion of the unitary or integrated bar and spacer.
[0026] FIG. 15 is a cross-sectional view of a refiner filling piece having a variable coating on a unitary or integrated bar and spacer in accordance with another embodiment of the invention in which the variable coating is a nonlinearly variable coating that entirely covers the leading surface.
[0027] FIG. 16 is a cross-sectional view of a refiner filling piece having a linearly variable coating on both the leading and trailing surfaces of a unitary or integrated bar and spacer in accordance with another embodiment of the invention.
[0028] FIG. 17 is a cross-sectional view of a refiner filling piece having a nonlinearly variable coating on both the leading and trailing surfaces of a unitary or integrated bar and spacer in accordance with another embodiment of the invention.
[0029] FIG. 18 is a cross-sectional view of a refiner filling piece having another form of nonlinearly variable coating on the leading surface of a unitary or integrated bar and spacer in accordance with another embodiment of the invention.
[0030] FIG. 19 is a cross-sectional view of a refiner filling piece having another form of nonlinearly variable coating on both the leading and trailing surfaces of a unitary or integrated bar and spacer in accordance with another embodiment of the invention.
[0031] FIG. 20 is a cross-sectional view of a refiner filling piece having a linearly variable coating on the leading surface of a tilted unitary or integrated bar and spacer in accordance with another embodiment of the invention.
[0032] FIG. 21 is a cross-sectional view of a refiner filling piece having a linearly variable coating on both the leading and trailing surfaces of a tilted unitary or integrated bar and spacer in accordance with another embodiment of the invention.
[0033] FIG. 22 is a cross-sectional view of a refiner filling piece having a nonlinearly variable coating on the leading surface of a tilted unitary or integrated bar and spacer in accordance with another embodiment of the invention.
[0034] FIG. 23 is a cross-sectional view of a refiner filling piece having another form of nonlinearly variable coating on the leading surface of a tilted unitary or integrated bar and spacer in accordance with another embodiment of the invention.
[0035] It will be noted that throughout the appended drawings, like features are identified by like reference numerals.
DETAILED DESCRIPTION
[0036] Disclosed herein are various embodiments of a refiner filling piece having refiner bars that are coated with a variable coating. The present specification also discloses a refiner having one or more refiner filling pieces that include the refiner bars coated with the variable coating.
[0037] FIG. 1 is a perspective view of a refiner generally denoted by reference numeral 10 in accordance with one embodiment of the present invention. In the embodiment depicted in FIG. 1, the refiner 10 has a housing 12, a stator 14 and a rotor 16. The rotor rotates about an axis of rotation and cooperates with the stator to mechanically treat a pulp (or pulp suspension) containing cellulosic fibers. The axis of rotation defines an axial direction and a radial direction. In the illustrated embodiment of FIG. 1, the refiner is a disc-type refiner having a replaceable refiner filling. The refiner filling is composed of a plurality of refiner filling pieces. In the example of FIG. 1, the refiner filling pieces are segments of a generally flat, annular disc-like or plate-like structure (also referred to herein as a plate). However, it will be appreciated that the refiner filling pieces may be conical filling pieces in a conical refiner. For the purposes of this specification, the expression refiner filling piece shall be construed as encompassing a flat disc-like plate or an arcuate segment thereof, or a conical structure or an angular segment thereof. For a disc-type refiner, the refiner filling piece may be a one-piece circular plate, an annular plate or an arcuate segment that is assembled with other arcuate segments to form the complete circular or annular plate. Analogously, for a conical refiner, the refiner filling piece may be a one-piece conical (or frusto-conical) structure or an angular segment of a cone (or frustum) that is assembled with other such angular segments to form a complete conical (or frusto-conical) structure. From the foregoing, it is to be understood that a refiner filling piece may be circular, annular or conical (i.e. defining a complete 360-degree component) or segmented (i.e. defining an arcuate or angular component of less than 360 degrees that is designed to be assembled with other such segments to form the complete circular or annular plate or to form the cone, as the case may be).
[0038] FIG. 1 depicts the replacement of a refiner filling piece 20 on the stator 14. The refiner filling piece 20 may be mounted to the stator 14 using fasteners, e.g. threaded fasteners, as shown. In this example, a plurality of refiner filling pieces 20 are mounted to the stator 14 in an annular arrangement to constitute a stator-side refiner plate. In the embodiment depicted in FIG. 1, the stator 14 is mounted to a door-like cover 15 that pivots about a hinge mechanism to enable replacement of the refiner filling piece(s) 20.
[0039] FIG. 2 is another perspective view of the refiner 10 of FIG. 1 showing the replacement of a refiner filling piece 20 on the rotor 16. The refiner filling piece 20 may be mounted to the rotor 16 using fasteners, e.g. threaded fasteners, as shown. A plurality of refiner filling pieces 20 are mounted to the rotor 16 in an annular arrangement to constitute a rotor-side refiner plate. In the embodiment depicted in FIG. 2, the rotor 16 is mounted inside the housing 12 of the refiner 10.
[0040] In the embodiment of FIGS. 1 and 2, the refiner filling piece 20 is a replaceable refiner filling piece having a segmented plate-like shape. When servicing the refiner, the refiner filling may be replaced, if worn, by replacing the assembly of refiner filling pieces that constitute the filling. For example, as shown in FIG. 2A, four refiner filling pieces shaped as four arcuate segments may be assembled to provide a complete annular plate structure for a disc-type refiner. The angular arc of each arcuate or segmented filling piece may be varied from what is shown in these examples. The angular arc of the filling piece may be, for example, 360 degrees, 180 degrees, 90 degrees, 45 degrees, 30 degrees, 22.5 degrees, 20 degrees, 15 degrees, 10 degrees, etc. so that when assembled they constitute an annular arrangement having a full 360 degrees. FIG. 2A also shows that the annular refiner filling piece may be characterized by an inner diameter (ID) and an outer diameter (OD). The refiner filling piece thus extends radially from the inner diameter to the outer diameter. It will also be appreciated that a complete plate or annulus of arcuate or segmented filling pieces may be composed of filling pieces of different shapes, e.g. one 180-degree filling plus two 90-degree filling pieces, two 90-degree filling pieces plus four 45-degree filling pieces, three 60-degree filling pieces plus six 30-degree filling pieces, and so on.
[0041] As illustrated in FIGS. 3-10, the refiner filling piece 20 has a base 22. The base may have a uniform thickness in an axial direction in some embodiments although it may alternatively have a non-uniform thickness. The base extends radially from an inner diameter ID to an outer diameter OD as depicted in FIG. 2A. The refiner filling piece 20 has a plurality of spaced-apart refiner bars 30 (also known as blades). The bars may be spaced apart with a uniform or non-uniform groove width, i.e. the spacing between adjacent bars may vary or be constant. Optionally, the refiner bars are spaced apart by spacers 24 although in other implementations, there may be no spacers. Each bar is defined by a bar length BL extending toward the outer diameter, i.e. extending generally radially, and is defined by a bar height BH protruding generally axially from the base. The bar height may be constant or varying. In some implementations, the bar height may be, for example, a value that is within the range of 3 to 14 mm. At least some of the refiner bars 30 have a leading surface 32 coated with a variable coating 34 in an embodiment of this invention.
[0042] The variable coating is applied non-uniformly, unlike the prior art, on the leading surface of the bar and optionally also, or alternatively, on the trailing surface of the bar. The coating is variable in thickness, i.e. the coating varies dimensionally or geometrically. The thickness of the coating varies so that the coating is thickest in areas where it provides maximum wear resistance and minimizing or eliminating application in areas with limited value or where excess coating may be detrimental.
[0043] As depicted in FIGS. 3-10, the variable coating has a coating thickness that is variable along either the height of the refiner bar (e.g. increasing from the base to the top of the bar) or variable in the radial direction (e.g. increasing from the inner diameter ID to the outer diameter OD of the filling).
[0044] The coating thickness may be a function of bar height. For example, the coating thickness may increase with the height of the bar (e.g. the coating becomes thicker as the height increases to a maximum thickness at the top of the bar). This minimizes the stress concentration at the base of the bar where bending stresses are highest while maximizing the space at the base of the groove to maintain or improve hydraulic capacity. Furthermore, the variable coating reduces cost by not applying the coating where it is not needed or less effective.
[0045] The coating may also, or alternatively, be varied in thickness as a function of radial length, e.g. in a direction from the inner diameter ID (where the coating is least) to or toward the outer diameter OD (where is it greatest). This maximizes the open area or volume at the inner diameter ID which is very important for hydraulic capacity. Since the outer diameter OD of the filling piece typically has a peripheral velocity higher than that of the inner diameter ID (for a disc-type refiner), the outer diameter portion consumes more energy, applies more shear and compression, and performs the majority of the refining work. Accordingly, concentrating the coating in the outer region of the filling pieces will improve service life relative to the same amount of coating if uniformly applied.
[0046] FIG. 3 is a cross-sectional view of a refiner filling piece 20 having a variable coating 34 on a leading surface 32 of the bars 30. In the embodiment depicted in FIG. 3, the variable coating 34 has a coating thickness that varies axially with the bar height.
[0047] As shown in FIG. 3, the coating thickness in this example embodiment increases linearly with the bar height.
[0048] FIG. 3 also denotes a groove space that occupies the volume between a trailing surface of one bar and the coated leading surface of the bar immediately behind it. The coating on the leading surface of the bar inhibits wear of the bar and thus preserves the hydraulic capacity of the refiner by maintaining a desired groove space between adjacent bars.
[0049] Alternatively, in the embodiment depicted in FIG. 4, the variable coating 34 on the leading surface 32 of the bars 30 has a coating thickness that, for example, increases non-linearly with bar height. For example, in one specific implementation, the nonlinear coating may be coated parabolically or exponentially with the bar height. For example, the coating thickness may increase as a function of the square of the axial height.
[0050] Alternatively, in the embodiment depicted in FIG. 5, the variable coating 34 on the leading surface 32 of the bars 30 has a coating thickness that, for example, increases over a first portion of the bar height, then decreases over a second portion of the bar height and then increases over a third portion of the bar height.
[0051] FIG. 6 is a cross-sectional view of a refiner filling piece 20 having a variable coating 34 on a leading surface 32 and a thinner variable coating 36 on the trailing surface 38. In the specific example of FIG. 6, both the coatings on the leading and trailing surfaces increase linearly with the bar height although at different rates.
[0052] In the example embodiment depicted in FIG. 7, both the leading and trailing surfaces 32, 38 have respective variable coatings 34, 36 that increase nonlinearly with the bar height although at different rates.
[0053] In the example embodiment depicted in FIG. 8, the trailing surface has a thinner variable coating than the variable coating on the leading surface as in FIGS. 6 and 7. In FIG. 8, the thinner variable coating increases over the first portion of the bar height, then decreases over the second portion of the bar height and then increases over the third portion of the bar height.
[0054] FIG. 9 is a top view of a refiner filling piece 20 in accordance with one embodiment of the invention in which the variable coating 34 varies radially along a bar length BL on the leading surface 32. Specifically, in this example, the variable coating has a coating thickness that varies linearly along the bar length.
[0055] FIG. 10 is a top view of a refiner filling piece 20 in accordance with another embodiment of the invention in which the variable coating 34 varies radially along a bar length BL on the leading surface 32 and a thinner variable coating 36 varies radially along the bar length BL on the trailing surface 38. In this specific example, the variable coating has a coating thickness that varies linearly along the bar length. As shown in FIG. 10, the trailing surface has a thinner variable coating than the variable coating on the leading surface.
[0056] FIG. 11 depicts a conical refiner filling piece 20 to which a variable coating may be applied in accordance with another embodiment of the invention. The conical refiner filling piece 20 is characterized by an inner diameter ID and an outer diameter OD as denoted in FIG. 11. The refining bars 30 of the conical refiner filling piece 20 have a variable coating as described above which may vary in all of the different ways discussed above. In this example, the conical refiner filling piece 20 is a single unitary component defining the complete conical structure although it will be appreciated that the conical refiner filling piece may be a segmented conical filling piece that is assembled with other segmented conical filling pieces to constitute the complete conical (or frusto-conical) structure.
[0057] In some embodiments, the leading surface of all refiner bars has the variable coating, i.e. all of the refiner bars are coated with the variable coating. In other embodiments, only some of the leading surfaces of the refiner bars have the variable coating. For example, an alternating pattern of coated and uncoated bars may be implemented. As another example, every third or fourth bar may be coated. Conversely, every third or fourth bar may be uncoated.
[0058] In some embodiments, the variable coating extends along all of the bar length. In other embodiments, the variable coating extends only partially along the bar length. For example, the variable coating may extend over 90%, 80%, 70%, 60%, 50%, 40%, 30%, 20%, 10%, etc. of the length. As another example, one bar may be coated a first percentage with the next bar being coated a different percentage. In some embodiments, the variable coating extends from the base to the top of the bar, i.e. the coating covers all of the bar height. In other embodiments, the variable coating extends only over a portion of the bar height. For example, the variable coating may begin at a point higher than the base, e.g. the midpoint, at a quarter of the height, a third of the height, three-quarters of the height, etc.
[0059] FIGS. 12-23 depict other embodiments of the invention in which the variable coating is applied to a refiner bar having an integrated spacer. The spacer-integrated bar is also referred to herein as a unitary bar and spacer or an integrated bar and spacer. The spacer-integrated bar is a single monolithic structure or unit formed as a single piece, e.g. by casting or molding or other similar or suitable manufacturing technique. The spacer-integrated bar 31 has a bar portion 31a and a spacer portion 31b at the bottom of the bar portion. The spacer portion 31b is integrally formed with the bar portion 31a. The spacer-integrated bar 31 has an inverted T shape although it may have another shape like an L shape. The width of the spacer portion 31b may be varied to provide any desired spacing between the bars.
[0060] FIG. 12 is a cross-sectional view of a refiner filling piece 20 having a variable coating 34 on a unitary or integrated bar and spacer 31 in accordance with another embodiment of the invention in which the variable coating 34 is a linearly variable coating that begins at a point above the spacer portion 31b of the unitary bar and spacer (spacer-integrated bar) 31. In the embodiment of FIG. 12, the coating thickness increases with height. In another embodiment, the coating may decrease with height. In these illustrated embodiments, the variable coating is applied only to the bar portion 31a of the spacer-integrated bar and not to the spacer portion 31b. In the embodiment depicted in FIG. 12, the spacer-integrated bar 31 may be attached, affixed or secured to the base 22 using a solidifying substance 40 or filler material. The solidifying substance 40 may be a meltable metal substance that is first melted by applying heat and then solidifies to join the spacer-integrated bar 31 to the base 22. More specifically, the solidifying substance 40 may be a braze that has a lower melting point than the base and bar. For example, the braze may be a metal alloy containing silver, copper, iron or nickel. As an alternative to brazing, the spacer-integrated bar 31 may be attached, affixed or secured to the base 22 by welding. Alternatively, the spacer-integrated bar 31 may be attached, affixed or secured to the base 22 by any other equivalent or suitable metal-to-metal joining technique.
[0061] FIG. 13 is a cross-sectional view of a refiner filling piece 30 having a variable coating 34 on a unitary bar and spacer (spacer-integrated bar) 31 in accordance with another embodiment of the invention in which the variable coating 34 is a linearly variable coating that entirely covers the leading surface. In the embodiment of FIG. 13, the coating thickness increases linearly with height. In another embodiment, the coating may decrease with height.
[0062] FIG. 14 is a cross-sectional view of a refiner filling piece 20 having a variable coating on a spacer-integrated bar (unitary or integrated bar and spacer) 31 in accordance with another embodiment of the invention in which the variable coating 34 is a nonlinearly variable coating 34 that begins at a point above the spacer portion of the unitary or integrated bar and spacer 31. In the embodiment shown in FIG. 14, the coating thickness increases with height. In the embodiment of FIG. 14, the variable coating has a generally parabolic shape.
[0063] FIG. 15 is a cross-sectional view of a refiner filling piece 20 having a variable coating 34 on a spacer-integrated bar (unitary or integrated bar and spacer) 31 in accordance with another embodiment of the invention in which the variable coating 34 is a nonlinearly variable coating 34 that entirely covers the leading surface. In the embodiment of FIG. 15, the variable coating has a generally parabolic shape having a coating thickness that increases with height.
[0064] FIG. 16 is a cross-sectional view of a refiner filling piece 20 having a linearly variable coating 34 on both the leading and trailing surfaces of a spacer-integrated bar (unitary or integrated bar and spacer) 31 in accordance with another embodiment of the invention. The coating thickness of the variable coating on the leading surface may be the same as the coating thickness of the variable coating on the trailing surface. In a variant, the trailing surface may have a thinner coating. In another variant, the trailing surface may have a thicker coating.
[0065] FIG. 17 is a cross-sectional view of a refiner filling piece 20 having a nonlinearly variable coating 34 on both the leading and trailing surfaces of a spacer-integrated bar (unitary or integrated bar and spacer) 31 in accordance with another embodiment of the invention. The variable coating is parabolic in this example. The coating thickness of the variable coating on the leading surface may be the same as the coating thickness of the variable coating on the trailing surface. In a variant, the trailing surface may have a thinner coating. In another variant, the trailing surface may have a thicker coating.
[0066] FIG. 18 is a cross-sectional view of a refiner filling piece 20 having another form of nonlinearly variable coating 34 on the leading surface of a spacer-integrated bar (unitary or integrated bar and spacer) 31 in accordance with another embodiment of the invention. In the embodiment of FIG. 18, the thickness of the variable coating increases in height, then decreases and then increases again.
[0067] FIG. 19 is a cross-sectional view of a refiner filling piece 20 having another form of nonlinearly variable coating 34 on both the leading and trailing surfaces of a spacer-integrated bar (unitary or integrated bar and spacer) 31 in accordance with another embodiment of the invention. The coating thickness of the variable coating on the leading surface may be the same as the coating thickness of the variable coating on the trailing surface. In a variant, the trailing surface may have a thinner coating. In another variant, the trailing surface may have a thicker coating.
[0068] The refiner filling piece may alternatively have tilted refiner bars. The refiner bars may be tilted or angled relative to the base 22 thereby defining an acute angle of less than 90 degrees between the bar and the base. In one embodiment, the acute angle is 50 to 80 degrees. In a more specific embodiment, the acute angle is 60 to 70 degrees. The tilted refiner bars may be spacer-integrated bars. In other words, each tilted spacer-integrated bar may be a tilted unitary bar and spacer (tilted integrated bar and spacer).
[0069] FIG. 20 is a cross-sectional view of a refiner filling piece 20 having a linearly variable coating 34 on the leading surface of a tilted spacer-integrated bar (tilted unitary or integrated bar and spacer) 31 in accordance with another embodiment of the invention.
[0070] FIG. 21 is a cross-sectional view of a refiner filling piece 20 having a linearly variable coating 34 on both the leading and trailing surfaces of a tilted spacer-integrated bar (tilted unitary or integrated bar and spacer) 31 in accordance with another embodiment of the invention. In this example, the shape of the variable coating on the leading surface is different than the shape of the variable coating on the trailing surface. In a variant, the variable coating on the leading surface may be identical to the variable coating on the trailing surface. In another variant, the variable coating on the leading surface may be a different coating material than the material used for the variable coating on the trailing surface.
[0071] FIG. 22 is a cross-sectional view of a refiner filling piece 20 having a nonlinearly variable coating 34 on the leading surface of a tilted spacer-integrated bar (tilted unitary or integrated bar and spacer) 31 in accordance with another embodiment of the invention. The variable coating in this example is parabolic.
[0072] FIG. 23 is a cross-sectional view of a refiner filling piece 20 having another form of nonlinearly variable coating 34 on the leading surface of a tilted spacer-integrated bar (tilted unitary or integrated bar and spacer) 31 in accordance with another embodiment of the invention. The variable coating in this example is a complex shape defined initially by an increase in thickness with height, followed by a decrease in thickness and then an increase in thickness.
[0073] In another embodiment, a variable-thickness coating may be applied to a tilted bar or blade that is not a spacer-integrated bar. In this other embodiment, the refiner filling piece may have discrete spacers between the variably coated tilted bars. The refiner bars may be tilted or angled relative to the base thereby defining an acute angle of less than 90 degrees between the bar and the base. The acute may be 50 to 80 degrees. In a more specific implementation, the acute angle is 60 to 70 degrees. The tilted refiner bars may be all tilted at the same angle. In a variant, a tilt angle of the bars may vary from one bar to another. In another variant, some bars may have a first tilt angle and other bars may have a second tilt angle. In another variant, a first group of bars may have a first tilt angle, a second group of bars may have a second tilt angle, and a third group of bars may have a third tilt angle.
[0074] For the purposes of interpreting this specification, when referring to elements of various embodiments of the present invention, the articles a, an, the and said are intended to mean that there are one or more of the elements. The terms comprising, including, having, entailing and involving, and verb tense variants thereof, are intended to be inclusive and open-ended by which it is meant that there may be additional elements other than the listed elements.
[0075] This invention has been described in terms of specific embodiments, implementations and configurations which are intended to be exemplary only. Persons of ordinary skill in the art will appreciate that many obvious variations, refinements and modifications may be made without departing from the inventive concept(s) presented in this application. The scope of the exclusive right sought by the Applicant is therefore intended to be limited solely by the appended claims.
