Screen cylinder with improved slot width protection, and method for removing solid foreign matter from a solid suspension.

Abstract

To provide a slot cylinder comprising a hardened layer disposed in a slot region for reducing wear in the slot region.SOLUTION: The method includes a step of forming the outer portion of a container on the inner surface thereof prior to inversion of the container and forming the inner portion of the container on the outer surface thereof prior to inversion of the container, to form a layer of an elastomer or plastic or any combination thereof inside the container in an inverted manner. In an embodiment, the method includes a step of forming or bonding a leak-proof seal on the outer surface of the container prior to inversion of the container. The leak-proof seal provides access to the inner portion of the container when the leak-proof seal is opened subsequent to inversion of the container, and after inverting the container, at least a liquid is retained in the container even when an external force is applied to the container, without using an external structure to keep the leak-proof seal closed.SELECTED DRAWING: Figure 5

Description

Related Applications

[0001] This application claims the benefit of priority under 35 U.S.C. § 120 to U.S. Provisional Patent Application No. 62 / 839,314, filed Apr. 26, 2019, entitled “Screen Cylinder with Improved Slot Width Protection,” the entire content of which is incorporated herein by reference.

Technical Field

[0002] This specification generally relates to screen cylinders for removing oversized solid foreign matter from solid suspensions, and more specifically, to screen cylinders having improved slot width protection, and methods of making and using screen cylinders having improved slot width protection.

Background Art

[0003] In the paper industry, the papermaking process requires the production of pulp, which is a solid suspension of fibers such as cellulose fibers or other fibers. Depending on the fiber source, the pulp may contain solid foreign matter of various concentrations and sizes, such as wood chips, fiber bundles, metal pieces, cured adhesives, or other foreign matter. For example, as the use of recycled paper as a fiber source increases, the presence of cured adhesives, metal fragments, and wood chips in the pulp may increase. These oversized solid foreign matters can degrade the paper quality and / or cause disturbances in the pulp flow in the headbox of a Fourdrinier machine or other papermaking processes.

[0004] Before introducing pulp into the papermaking process, it is often screened to remove these excessive solid impurities. Pulp screening may be used to separate pulp based on fiber length or fiber stiffness. Pulp screening may be achieved by introducing pulp into a pressure screen, where acceptable portions of the pulp pass through the holes or slots of the screen. Solid impurities or unacceptable portions of the pulp (e.g., long or stiff fibers in the case of screening based on fiber characteristics) do not pass through the holes or slots of the screen and are discharged through the reject outlet. Pressure screens may also be used in industries other than the pulp and papermaking industries to remove excessive solid impurities from slurries and solid suspensions. [Overview of the project] [Problems that the invention aims to solve]

[0005] Therefore, there is a current demand for pressure screens with improved wear performance. Specifically, there is a current demand for screen cylinders that have a hardened layer in the slot area to reduce wear in the slot area. [Means for solving the problem]

[0006] In one or more aspects of the present disclosure, a screen cylinder may include a plurality of shaped bars, which are aligned longitudinally and connected at their mounting ends to at least one support ring. Each of the plurality of shaped bars may include an outer surface facing outward from at least one support ring, a first slot surface extending from the outer surface of the shaped bar to the mounting end opposite the outer surface, and a second slot surface extending from the outer surface of the shaped bar to the mounting end, opposite the first slot surface. The first slot surface of one shaped bar and the second slot surface of another immediately adjacent shaped bar may define a slot. The shaped bar may further include a hardened layer integrated with or installed thereon on at least a portion of the first slot surface of the shaped bar, the hardened layer having a Vickers hardness value greater than or equal to 500HV0.05, as determined in accordance with ASTM E384-11e1.

[0007] In another aspect of the present disclosure, a shaped bar of a screen cylinder for separating solid foreign matter from a solid suspension may include an outer surface installed at a mounting end and at the end opposite the mounting end. The shaped bar may further include a first slot surface extending from the outer surface of the shaped bar to the mounting end, and a second slot surface extending from the outer surface opposite the first slot surface to the mounting end. The shaped bar may further include a hardened layer integrated with or installed on at least a portion of the first slot surface, a portion of the second slot surface, or both, the hardened layer having a Vickers hardness value greater than or equal to 500HV0.05 as determined in accordance with ASTM E384-11e1.

[0008] In yet another aspect of this disclosure, a method for producing a hardened shaped bar for a screen cylinder may include providing a shaped bar including a mounting end and an outer surface facing the opposite direction from the mounting end. The shaped bar may further include a first slot surface extending from the outer surface of the shaped bar to the mounting end, and a second slot surface extending from the outer surface to the mounting end on the opposite side of the first slot surface. The method may further include forming a hardened layer on or integrated with at least a portion of the first slot surface. The hardened layer may have a Vickers hardness value greater than or equal to 500HV0.05, as determined in accordance with ASTM E384-11e1. The method may further include depositing a chromium layer on or on the hardened layer of the shaped bar.

[0009] In yet another aspect of this disclosure, a method for removing solid foreign matter from a solid suspension may include bringing the solid suspension into contact with a screen cylinder. The screen cylinder may include a plurality of shaped bars connected to at least one support ring and aligned longitudinally. Each of the plurality of shaped bars may include an outer surface facing outward from at least one support ring, a first slot surface extending from the outer surface of the shaped bar to the mounting end opposite the outer surface, and a second slot surface extending from the outer surface of the shaped bar to the mounting end, opposite the first slot surface. Each of the shaped bars may further include a hardened layer integrated with or installed thereon on at least a portion of the first slot surface of each shaped bar. The hardened layer may have a Vickers hardness value greater than or equal to 500HV0.05, as determined in accordance with ASTM E384-11e1. The first and second slot surfaces of adjacent pairs of irregularly shaped bars may define a plurality of slots in the screen cylinder, and contact between the solid suspension and the screen cylinder may allow at least a portion of the solid suspension to pass through the slots. The method may further include recovering an acceptable amount of solid suspension from the plurality of slots in the screen cylinder.

[0010] Please understand that both the above general description and the following detailed description illustrate various embodiments and are intended to provide an overview or framework for understanding the nature and characteristics of the subject matter of the claims. [Brief explanation of the drawing]

[0011] The accompanying drawings are included to provide a further understanding of various embodiments and are incorporated into this specification and constitute part thereof. These drawings illustrate various embodiments described herein and, together with this specification, serve to illustrate the principles and operation of the subject matter of the claims. [Figure 1] This figure schematically shows a front perspective view of a screen cylinder of one or more embodiments shown and described herein. [Figure 2A] This figure schematically shows a perspective view of a portion of the screen cylinder in Figure 1, illustrating a plurality of irregularly shaped bars connected to the support ring of the screen cylinder in one or more embodiments shown and described herein. [Figure 2B] This figure schematically shows another perspective view of a portion of the screen cylinder in Figure 1, showing a plurality of irregularly shaped bars connected to the support ring of the screen cylinder in one or more embodiments shown and described herein. [Figure 3] This figure schematically shows cross-sectional views of three shaped bars of the screen cylinder of Figure 1, in which the shaped bars have a chromium layer on the outer surface of the shaped bars, according to one or more embodiments shown and described herein. [Figure 4] Figure 3 schematically shows a cross-sectional view of a portion of a shaped bar, in which the slots have become larger as a result of wear on a portion of the first slot surface of the shaped bar after a period of operation, according to one or more embodiments shown and described herein. [Figure 5] This figure schematically shows a cross-sectional view of a shaped bar having a hardened layer and a chromium layer deposited on the hardened layer, according to one or more embodiments shown and described herein. [Figure 6A]This figure schematically shows a cross-sectional view of a shaped bar of one or more embodiments shown and described herein, having a hardened layer on a portion of the first slot surface of the shaped bar and a chromium layer overlapping the hardened layer. [Figure 6B] This figure schematically shows a cross-sectional view of a shaped bar of one or more embodiments shown and described herein, having a hardened layer on the first slot surface and outer surface of the shaped bar, and a chromium layer formed in the hardened layer. [Figure 6C] This figure schematically shows a cross-sectional view of a shaped bar having a hardened layer on the first slot surface and the second slot surface of the shaped bar, according to one or more embodiments shown and described herein. [Figure 6D] This figure schematically shows a cross-sectional view of a shaped bar of one or more embodiments shown and described herein, having a hardened layer on the entire outer surface of the shaped bar and a chrome coating applied to the hardened layer. [Figure 7] This figure schematically shows a cross-sectional view of a portion of a shaped bar, in which the hardened layer is integrally formed with the base material of the shaped bar, according to one or more embodiments shown and described herein. [Figure 8] This figure schematically shows a cross-sectional view of a portion of the cured layer of the irregularly shaped bar shown in Figure 7, according to one or more embodiments described herein. [Figure 9] This figure schematically shows a cross-sectional view of a portion of a shaped bar, in which the cured layer includes a coating applied to at least the first slot surface, the second slot surface, and the outer surface of the shaped bar, according to one or more embodiments shown and described herein. [Modes for carrying out the invention]

[0012] Next, we will refer in detail to embodiments of screen cylinders having hardened shaped bars, examples of which are illustrated in the accompanying drawings. Throughout the drawings, whenever possible, the same reference numerals are used to refer to the same or similar parts. Referring to Figures 1 and 2, a screen cylinder 10 of embodiments of the present disclosure is illustrated. The screen cylinder 10 may include a plurality of shaped bars 12, which are aligned longitudinally and connected at mounting ends 30 of the plurality of shaped bars 12 to at least one support ring 14. Referring to Figure 2, each of the shaped bars 12 may include an outer surface 32 facing outward from the support ring 14, a first slot surface extending from the outer surface 32 of the shaped bar 12 to the mounting end 30, and a second slot surface on the opposite side of the first slot surface, extending from the outer surface 32 of the shaped bar 12 to the mounting end 30. The first slot surface of one shaped bar and the second slot surface of another immediately adjacent shaped bar may define a slot 20. Each of the shaped bars may include a hardened layer integrated with or installed on at least a portion of the first slot surface of the shaped bar 12, the hardened layer having a Vickers hardness value greater than that of the base material of the shaped bar 12. In some embodiments, the shaped bar may include a chromium layer installed on the outer surface 32 of the shaped bar 12 or on the hardened layer. During operation of the screen cylinder 10, an acceptable portion of the solid suspension passes through the slots 20 of the slotted cylindrical wall 16. The hardened layer applied to the shaped bar 12 can reduce wear on the slot surface of the shaped bar 12 caused by the abrasive solid components of the solid suspension. Reducing wear can reduce the widening of the slots 20, thereby maintaining the separation efficiency of the screen cylinder 10 over time. Reducing wear on the slot surface and maintaining the separation efficiency of the screen cylinder 10 over time can increase the service life of the screen cylinder.

[0013] Unless otherwise indicated, nothing in this specification is intended to imply that any of the methods described herein require their steps to be performed in a specific order or that any particular orientation is required in any apparatus. Thus, where a method claim does not actually recite the order in which its steps are to be performed, or where any apparatus claim does not actually recite an order or orientation for individual components, or where the claims or the specification do not otherwise specifically recite that the steps are limited to a specific order, or where no particular order or orientation is otherwise recited for components of an apparatus, there is no intention at all to imply an order or orientation in any respect. This applies to all possible bases for ambiguous interpretation, including logical matters regarding the sequence of steps, operational flow, order of components, or orientation of components; the plain meaning derived from grammatical construction or punctuation; and the number or type of embodiments described in this specification.

[0014] The terms related to directions used in this specification, such as up, down, right, left, front, back, upper, and bottom, are described only with respect to the drawn figures and the coordinate axes given therein and are not intended to represent absolute directions.

[0015] As used in this specification, the singular forms "a", "an", and "the" include the plural unless the context clearly indicates otherwise. Thus, for example, a reference to "a" component includes embodiments having two or more such components unless the context clearly indicates otherwise.

[0016] As used in this specification, the term "longitudinal" may refer to a direction or orientation generally parallel to the central axis A of the screen cylinder.

[0017] As used in this specification, the term "radial" may refer to a direction along any radius extending outward from the central axis A of the screen cylinder (Figure 1).

[0018] As used herein, the terms “upstream” and “downstream” may refer to the position of each part relative to the direction of flow of the solid suspension or slurry. In the case of the screen cylinder of this disclosure, the flow of the solid suspension generally proceeds from the outer surface 32 of the shaped bar 12 toward the mounting end 30 of the shaped bar 12.

[0019] As used herein, the terms “solid foreign matter” or “excessive solid foreign matter” may refer to solid objects such as wood chips, metal fragments, dried adhesives, or other foreign matter that is not intended and undesirable to be present in a solid suspension or slurry and can be distinguished from solid components intended to be present in a solid suspension, such as fibers.

[0020] Unless otherwise specified, the Vickers hardness values ​​of the base material, hardened layer 50, and chromium layer 40 provided herein refer to Vickers hardness values ​​determined using an indentation load of 0.05 kilograms-force (kgf) (approximately 0.49 N) in accordance with ASTM E384-11e1.

[0021] In the pulp and paper industries, pulp screening can be achieved by a pressure screening process using a screen cylinder. The pressure screening process may involve introducing a solid suspension, such as a solid suspension of fibers, into the screen cylinder. The fibers can be any type of fiber, but are not limited to cellulose fibers, cotton fibers, fiberglass fibers, or other fibers. The screen cylinder may be an inward-flow screen cylinder, where the permissible portion of the solid suspension flows radially inward through the screen cylinder, or an outward-flow screen cylinder, where the permissible portion of the solid suspension flows radially outward through the screen cylinder. The screen cylinder may include a rotor or other device that can function to remove solid impurities from the screen cylinder. Some screen cylinders for pressure screening pulp or other solid suspensions and slurries may have a modular screen cylinder comprising a solid metal cylinder through which multiple drilled or milled holes or slots pass. However, these modular screen cylinders provide limited throughput through the screen because the slot area through which the permissible portion of the solid suspension can pass is limited. The pulp and paper markets are driving demand for higher efficiency in pulp screening processes for higher throughput, as well as greater ability to separate excessive solid impurities from solid suspensions.

[0022] To improve the throughput of a pressure screening process, a screen cylinder has been developed that includes a plurality of longitudinally aligned shaped bars, the shaped bars defining a plurality of slots extending along the length of the screen cylinder. Referring to Figures 1, 2A, and 2B, a screen cylinder 10 of the present disclosure including a plurality of shaped bars 12 is schematically shown. The screen cylinder 10 includes a plurality of shaped bars 12 that are aligned longitudinally and connected to at least one support ring 14 at the mounting ends 30 of the plurality of shaped bars 12. In some embodiments, the at least one support ring 14 may include a plurality of support rings 14. The screen cylinder 10 may include annular end flanges 19 at both axial ends of the screen cylinder 10.

[0023] Each of the shaped bars 12 may be aligned longitudinally with respect to the central axis A of the screen cylinder 10 and with respect to each of the other shaped bars 12. The shaped bars 12 may be arranged side by side along the circular inner or outer circumference of the support ring 14 to form a slotted cylindrical wall 16. The slotted cylindrical wall 16 formed by a plurality of shaped bars 12 may include slots 20 defined between each pair of adjacent shaped bars 12. The slots 20 may extend the length of the screen cylinder 10 between the two annular end flanges 19. Further features and aspects of the support structure and operation of the screen cylinder 10 of this disclosure can be found in U.S. Patent No. 8,469,198, the entire contents of which are incorporated herein by reference.

[0024] By having slots 20 that extend along the length of the screen cylinder 10, a screen cylinder 10 including multiple shaped bars 12 may generally provide an increased opening area through which an acceptable solid suspension can pass. The wider opening area provided by the slots 20 of the screen cylinder 10 can provide higher throughput through the screen cylinder 10 compared to a unit-type screen cylinder having holes or slots made in a metal cylinder by drilling or milling. In Figures 1, 2A, and 2B, the screen cylinder 10 is shown as an outward-flow screen cylinder 10, and the acceptable solid suspension flows radially outward through the slots 20. However, it is understood that the features of this disclosure can be equally well applied to inward-flow screen cylinders or any other type of pressure screen device utilizing multiple shaped bars. The screen cylinder 10 may function to separate solid foreign matter from a solid suspension.

[0025] Referring to Figure 3, one embodiment of the irregularly shaped bar 12 is shown. Each irregularly shaped bar 12 may have a mounting end 30 connected to a support ring 14. Each irregularly shaped bar 12 may have an outer surface 32 facing outward from at least one support ring 14. Multiple outer surfaces 32 of irregularly shaped bars 12 may form a cylindrical wall 16 (Figure 1) with slots in the screen cylinder 10. Referring again to Figure 3, each irregularly shaped bar 12 may have a first slot surface 34 extending from the outer surface 32 of the irregularly shaped bar 12 to the mounting end 30 on the opposite side of the outer surface 32. Each irregularly shaped bar 12 may have a second slot surface 36 on the opposite side of the first slot surface 34, extending from the outer surface 32 of the irregularly shaped bar 12 to the mounting end 30. The first slot surface 34 of one irregularly shaped bar 12 and the second slot surface 36 of another irregularly shaped bar 12 define one of the slots 20 of the screen cylinder 10. When two irregularly shaped bars 12 are said to be "immediately adjacent," it means that these two irregularly shaped bars 12 are next to each other, and therefore the first slot surface 34 of the first irregularly shaped bar and the second slot surface 36 of the second irregularly shaped bar define a slot 20, provided that no other irregularly shaped bar is installed between the first and second irregularly shaped bars.

[0026] The first slot surface 34 may have a first outline, and the second slot surface 36 may have a second outline. The second slot surface 36 may meet the outer surface 32 of the adjacent irregularly shaped bar 12 at a nose 38 that protrudes toward the first slot surface 34 of the adjacent irregularly shaped bar 12. At the nose 38, the second outline of the second slot surface 36 of one irregularly shaped bar 12 may come close to the first outline of the first slot surface 34 of another adjacent irregularly shaped bar 12. Therefore, the narrowest part of the slot 20 may be defined between the nose 38 of the second slot surface 36 of the irregularly shaped bar 12 and the first slot surface 34 of the adjacent irregularly shaped bar. Downstream of the nose 38, the second outer rim of the second slot surface 36 of the irregularly shaped bar 12 and the first outer rim of the first slot surface 34 of the immediately adjacent irregularly shaped bar 12 may separate, widening the width of the slot 20 downstream of the nose 38. As described above, the flow of the solid suspension through the slot 20 generally proceeds from the outer surface 32 of the irregularly shaped bar 12 toward the mounting end 30. The first and second outer rims may have shapes other than those shown in Figure 3. For example, in this embodiment, the first slot surface 34, the second slot surface 36, or both may include a smooth or linear surface extending from the mounting end 30 of the irregularly shaped bar 12 toward the outer surface 32, or each may have an outer rim with a generally constant curvature from the mounting end 30 of the irregularly shaped bar 12 toward the outer surface 32. It is understood that the first slot surface 34 and the second slot surface 36 may have any preferred shape for manufacturing a screen cylinder that removes excessive solid foreign matter from slurries and solid suspensions.

[0027] Referring to Figure 3, each of the irregularly shaped bars 12 may include a chromium layer 40 applied to one or more surfaces. Specifically, the irregularly shaped bar 12 may include a chromium layer 40 applied to its outer surface 32. The outer surface 32 of the irregularly shaped bar 12 may be subjected to pressure pulses from the rotor, which provide sufficient cleaning action to remove excessive solid foreign matter from the slotted cylindrical wall 16 (Figure 1) of the screen cylinder 10. The chromium layer 40 on the outer surface 32 may increase the hardness of the outer surface 32, thereby reducing wear caused by these pressure pulsations. The chromium layer 40 may have a Vickers hardness value (HV) of 900HV0.05 to 1000HV0.05, determined using an indentation load of 0.05 kgf (approximately 0.49 N) according to ASTM E384-11e1.

[0028] The chromium layer 40 may be applied to the outer surface 32 of the shaped bar 12 after the screen cylinder 10 has been assembled. The chromium layer 40 may be applied using an electroplating process. When the screen cylinder 10 is electroplated, chromium is usually deposited preferentially in the region with the least resistance to the flow of electricity, which is usually the outer surface 32 of the parallel bar 12. Because chromium is deposited on the surface with the least resistance, the chromium layer 40 may be uneven and non-uniform across the entire outer edge surface of the shaped bar 12. As shown in Figure 3, the chromium layer 40 may be thicker in areas with low electrical resistance, thinner in areas with higher electrical resistance, or may not be present at all. For these reasons, it may be difficult to deposit the chromium layer 40 on the first slot surface 34 and / or second slot surface 36 of the shaped bar 12, which have greater resistance to the flow of electricity from a geometric standpoint compared to the outer surface 32 of the shaped bar 12. As a result, the chromium layer 40 on the first slot surface 34 and / or the second slot surface 36 may be very thin or not even present.

[0029] The screen cylinder 10 can be subjected to electroplating for a sufficient amount of time for a chromium layer 40 to form on the first slot surface 34 and the second slot surface 36. However, chromium plating is very expensive, and environmental regulations on the use of chromium and chromium processes are increasing. In addition, prolonged exposure to the electroplating process may only increase the non-uniformity of the chromium layer 40. This non-uniformity can result in variations in slot width from one slot 20 to the next, and along the longitudinal length of the slot 20. Even if a chromium layer 40 is deposited on each of the multiple irregularly shaped bars 12 before the assembly of the screen cylinder 10, the chromium layer 40 may still be non-uniform, resulting in inconsistent thickness of the chromium layer 40 across the entire outer surface of the irregularly shaped bars 12. Grinding the chromium layer 40 after electroplating to produce a more uniform chromium layer 40 can be labor-intensive and may waste the expensive chromium electroplated onto the surface of the irregularly shaped bars 12.

[0030] Irregularities in the chromium layer 40 produced by electroplating may result in areas on the first slot surface 34 and the second slot surface 36 having a thin chromium layer 40, or areas where the chromium layer 40 is not deposited. While the thin chromium layer 40 may initially provide some protection from wear, it can wear away and expose the underlying base material. If no chromium layer 40 is formed on the slot surface, the base material, which may have a Vickers hardness value less than or equal to 400HV0.05, may be directly exposed to the flow of abrasive solid suspension through the slot 20. In either case (for example, with or without a thin chromium layer 40 on the first slot surface 34 and / or the second slot surface 36), the first slot surface 34 and / or the second slot surface 36 may experience excessive wear during the operation of the screen cylinder 10, resulting in a change in slot width and a reduction in the separation efficiency of the screen cylinder 10.

[0031] Referring to Figure 4, a typical wear pattern of the shaped bar 12 is schematically shown. In Figure 4, the dashed line represents the original outline of the first slot surface 34 before the screen cylinder 10 is put into use, and the solid line represents the outline of the first slot surface 34 after the screen cylinder 10 has been used for a period of time. As shown in Figure 4, wear can be greatest in a portion of the first slot surface 34 that crosses the slot 20 perpendicularly from the nose 38 of the adjacent shaped bar 12. As the first slot surface 34 wears in the area very close to the nose 38 of the adjacent shaped bar 12, the slot width W may increase over time. An increasing slot width W can increase the throughput of the screen cylinder 10, but it can also reduce the efficiency of the screen cylinder 10 in separating excessive solid foreign matter from the solid suspension. Thus, wear can result in an increase in the concentration and / or average size of solid foreign matter and debris that pass through the screen cylinder 10 and enter the solid suspension that is acceptable downstream of the screen cylinder 10. As a result, a screen cylinder 10 having a thin chromium layer 40 on the first slot surface 34 and / or the second slot surface 36, or lacking a chromium layer 40, may have a shortened service life when used to remove solid foreign matter from a solid suspension of cellulose fibers or other solid components. In some cases, the service life can be shortened to as little as 3 to 12 months. Therefore, in order to reduce wear on the screen cylinder 10 and maintain separation efficiency, it is necessary to improve the hardness of the first slot surface 34, the second slot surface 36, or both in the area of ​​the slot 20, thereby extending the service life of the screen cylinder 10.

[0032] As described above, the present disclosure relates to a shaped bar 12 having a hardened layer capable of reducing wear on at least a first slot surface 34, and a screen cylinder including the shaped bar 12. Referring to Figure 5, the shaped bar 12 of the screen cylinder 10 of the present disclosure for separating solid foreign matter from a solid suspension may include a mounting end 30, an outer surface 32 located on the opposite end of the mounting end 30, a first slot surface 34 extending from the outer surface 32 of the shaped bar 12 to the mounting end 30, and a second slot surface 36 on the opposite side of the first slot surface 34, extending from the outer surface 32 to the mounting end 30. The shaped bar 12 of the present disclosure further includes a hardened layer 50 which may be integrated with or located on at least a portion of the first slot surface 34, a portion of the second slot surface 36, or both, the hardened layer 50 may have a Vickers hardness value greater than the Vickers hardness of the base material of the shaped bar 12. The hardened layer 50 may have a Vickers hardness value greater than or equal to 500HV0.05, greater than or equal to 700HV0.05, greater than or equal to 900HV0.05, greater than or equal to 1000HV0.05, greater than or equal to 1100HV0.05, or greater than or equal to 1200HV0.05. In some embodiments, the irregularly shaped bar 12 may additionally include a chromium layer 40 placed on the outer surface 32 (for example, when the hardened layer 50 is integrated with the base material 46) or a chromium layer 40 placed on the hardened layer 50 (for example, when the hardened layer 50 is coated on the outer surface 34 of the base material 46). Therefore, it should be understood that the chromium layer 40 is different from the hardened layer 50 and may be deposited on top of the hardened layer 50. In some embodiments, the irregularly shaped bar 12 may include a hardened layer 50 without the chromium layer 40.

[0033] As shown in Figure 5, when multiple shaped bars 12 are arranged longitudinally and adjacent to each other, the first slot surface 34 of one shaped bar 12 and the second slot surface 36 of another immediately adjacent shaped bar 12 define one of the slots 20 of the screen cylinder 10. The slot 20 may have a slot width W sufficient to allow a portion of the solid suspension to pass through the slot 20 while preventing the passage of excessive solid foreign matter. The slot 20 may have a slot width W that is the shortest distance between the first slot surface 34 of one shaped bar 12 and the second slot surface 36 of the immediately adjacent shaped bar 12. In the case of a screen cylinder 10 for screening paper pulp, the slot 20 may have a slot width W greater than or equal to 80 μm (0.08 mm), for example, 0.08 mm to 1.5 mm. The slot widths W disclosed herein are generally acceptable for screening paper pulp. However, it is understood that, in other industrial applications such as mining and exploration, food processing, water treatment, or other industries, the spacing between the shaped bars 12 and the slot width W may be larger or smaller depending on the specific industrial application. The slot width W of the slot 20 may be constant along the longitudinal length of the shaped bar 12. In some embodiments, the slot width W of the slot 20 may vary within tolerances having a size of less than or equal to 15 μm, less than or equal to 10 μm, less than or equal to 8 μm, less than or equal to 7 μm, or less than or equal to 6 μm when the screen cylinder 10 is fully assembled.

[0034] Each of the irregularly shaped bars 12 may include a base material 46. The base material 46 may be a rigid metal having sufficient strength to withstand pressure pulses from the rotor without deformation or fracture. In some embodiments, the base material 46 may be stainless steel, for example, 304 stainless steel or 316 stainless steel. The base material 46 without the hardened layer 50 may have a Vickers hardness value lower than the Vickers hardness value of the chromium layer 40, the hardened layer 50, or both. In some embodiments, the base material 46 may have a Vickers hardness less than 500HV0.05, less than or equal to 450HV0.05, less than or equal to 425HV0.05, or less than or equal to 400HV0.05. In some embodiments, the base material 46 may not be annealed.

[0035] Referring again to Figure 5, the hardened layer 50 may be integrated with or installed on the base material 46 of the shaped bar 12. The hardened layer 50 may be installed on any portion of the first slot surface 34, the second slot surface 36, the outer surface 32, or a combination thereof. Referring to Figure 6A, in some embodiments, the hardened layer 50 may be integrated with or installed on at least a portion of the first slot surface 34 of the shaped bar 12. As described above, the first slot surface 34 closest to the nose 38 of the immediately adjacent shaped bar 12 may be the region of the outer edge surface of the shaped bar 12 that experiences the greatest wear from the flow of solid suspension through the slot 20. The hardened layer 50 may also be integrated with or installed on a portion of each of the outer surface 32, the second slot surface 36, or both of the shaped bar 12.

[0036] Referring to Figure 6B, in some embodiments, the hardened layer 50 may be integrated with or installed on the first slot surface 34 and the outer surface 32 of the shaped bar 12. If a chromium layer 40 is present, it may be deposited on top of the hardened layer 50 on the outer surface 32 of the shaped bar 12. Referring to Figure 6C, in some embodiments, the hardened layer 50 may be integrated with the first slot surface 34 and the second slot surface 36. The hardened layer 50 on the second slot surface 36 may extend to cover the nose 38 of the shaped bar 12. If a chromium layer 40 is present, it may be formed on the outer surface 32 of the shaped bar 12 and on a portion of the hardened layer 50 in the vicinity of the outer surface 32. Referring to Figure 6D, in some embodiments, the hardened layer 50 may be integrated with or installed on each of the entire outer edge surfaces of the shaped bar 12, the entire outer edge surface including at least the outer surface 32, the first slot surface 34, and the second slot surface 36. As used herein, the term “entire outer surface” may mean that the hardened layer 50 is integrated with or installed on at least 80%, at least 85%, at least 90%, at least 95%, or at least 99% of the outer surface of the shaped bar 12. In some embodiments, the hardened layer 50 may be integrated with or installed on at least 20%, at least 50%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, or at least 99% of the outer surface of the shaped bar 12.

[0037] The cured layer 50 may have a thickness sufficient to reduce or prevent wear on the first slot surface 34 and / or second slot surface 36 of the irregularly shaped bar 12 by protecting the first slot surface 34 and / or second slot surface 36 from abrasive components of the solid suspension passing through the slot 20. For example, but not limited to, the cured layer 50 may have a thickness of greater than or equal to 5 μm, greater than or equal to 10 μm, greater than or equal to 15 μm, or greater than or equal to 20 μm. In embodiments, the cured layer 50 may have a thickness of 5 μm to 300 μm, 5 μm to 250 μm, 5 μm to 200 μm, 5 μm to 100 μm, 5 μm to 50 μm, 5 μm to 30 μm, 10 μm to 300 μm, 10 μm to 100 μm, or 10 μm to 50 μm. In some embodiments, the cured layer 50 may have a thickness greater than 300 μm without departing from the scope of the present disclosure.

[0038] The hardened layer 50 may have sufficient hardness to reduce wear on the first slot surface 34 and / or the second slot surface 36 during operation of the screen cylinder 10. The hardened layer 50 may have a hardness greater than that of the base material 46 of the shaped bar 12. For example, the hardened layer 50 may have a Vickers hardness value greater than approximately 400 HV 0.05, which is the Vickers hardness value of cold-rolled stainless steel. In embodiments, the hardened layer 50 may have a Vickers hardness value greater than or equal to 500 HV 0.05, greater than or equal to 700 HV 0.05, greater than or equal to 900 HV 0.05, greater than or equal to 1000 HV 0.05, greater than or equal to 1100 HV 0.05, or greater than or equal to 1200 HV 0.05. The hardened layer 50 may have a Vickers hardness value of 500HV0.05 to 5000HV0.05, 700HV0.05 to 2000HV0.05, or 1000HV0.05 to 1500HV0.05. The Vickers hardness value may be determined by measurement performed in accordance with the standard test method ASTM E384-11e1.

[0039] Referring again to Figure 5, the hardened layer 50 may have a hardened outer surface 56 of uniform dimensions and smoothness. Providing the hardened layer 50 with a hardened outer surface 56 of uniform dimensions may provide a more uniform slot width W along the length of the screen cylinder 10, and a more uniform slot width W from one slot 20 to the adjacent slot. The hardened layer 50 having a hardened outer surface 56 with a smoother surface finish may also reduce resistance to the flow of the allowable portion of the solid suspension through the slots 20 and may promote a greater flow rate of the allowable portion of the solid suspension through the screen cylinder 10. In other words, a smoother surface finish of the hardened outer surface 56 compared to the base material or chromium layer 40 may allow the solid (e.g., fibers) of the allowable portion of the solid suspension to pass through the slots 20 more easily, thus increasing the throughput of the screen cylinder 10 while maintaining effective separation of excessive solid foreign matter from the solid suspension.

[0040] The dimensional consistency and smoothness of the outer surface 56 of the hardened layer may be a function of the variation in the thickness of the hardened layer 50. In some embodiments, the hardened layer 50 may have a standard deviation of thickness of less than or equal to 5 μm, less than or equal to 2 μm, less than or equal to 1 μm, or less than or equal to 0.5 μm. The smoothness of the surface finish of the outer surface 56 of the hardened layer may be quantified by the surface roughness Ra value of the outer surface 56 of the hardened layer. In some embodiments, the outer surface 56 of the hardened layer may have a surface roughness Ra that is smaller than the surface roughness Ra of the base material 46 before the hardened layer 50 is formed. In some embodiments, the outer surface 56 of the cured layer may have a surface roughness Ra smaller than the surface roughness Ra of the base material 46 by a magnitude greater than or equal to 0.025 μm, greater than or equal to 0.030 μm, greater than or equal to 0.050 μm, or greater than or equal to 0.100 μm. In some embodiments, the outer surface 56 of the cured layer may have a surface roughness Ra of 0.08 to 0.30 μm, 0.09 to 0.25 μm, or 0.09 to 0.20 μm. The surface roughness Ra of the outer surface 56 of the cured layer and / or the base material 46 before application of the cured layer 50 may be determined according to a standard test method known in the art, such as ASTM A 480 / 480 M. As described above, the reduced surface roughness of the outer surface 56 of the hardened layer can give the irregularly shaped bar 12 a smoother surface finish, which can facilitate an increase in the allowable flow rate of the solid suspension through the screen cylinder 10.

[0041] In some embodiments in which a chromium layer 40 may be applied, the hardened layer 50 may have an electrical conductivity similar to or slightly less than that of the base material 46 and other metal parts of the screen cylinder 10 in order to reduce the difference in electrical resistance during the electroplating process that forms the chromium layer 40 on the hardened layer 50. In some embodiments, the hardened layer 50 may have the same electrical conductivity as the base material 46 of the multiple irregularly shaped bars 12. In some embodiments, the hardened layer 50 may have an electrical conductivity that is within 10% of the electrical conductivity of the base material 46. The same or similar electrical conductivity can allow the chromium layer 40 to be electroplated onto the hardened layer 50. As described above, during electroplating to produce the chromium layer 40, chromium is preferentially deposited in the region of minimum electrical resistance (e.g., the region of maximum electrical conductivity). Therefore, if the conductivity of the hardened layer 50 is substantially lower than the electrical conductivity of the base material 46 or other metal parts of the screen cylinder 10, chromium may preferentially deposit on the base material 46 or other metal parts that have greater conductivity and lower electrical resistance, rather than on the hardened surface of the shaped bar 12, such as the outer surface 32 of the shaped bar 12. If the electrical conductivity of the hardened layer 50 is substantially lower than that of the base material 46 or other metal components of the screen cylinder 10, the chromium layer 40 formed on the hardened layer 50 on the outer surface 32 of the shaped bar 12 may be very thin or absent, and chromium may preferentially deposit on metals with greater electrical conductivity. If the electrical conductivity of the hardened layer 50 is less than that of the base material 46 but within 10% thereof, a chromium layer 40 may deposit on the hardened layer 50, but this may require additional time in the chromizing process and / or the chromium layer 40 may have a thinner thickness compared to chromizing the base material 46 without the hardened layer 50. In some embodiments in which the chromium layer 40 is not added, the hardened layer 50 may have an electrical conductivity that differs from the electrical conductivity of the base material 46 by more than 10%.

[0042] Referring to Figure 7, in some embodiments, the hardened layer 50 may be integrated with the base material 46. As used herein, the term “integrated with” means that the hardened layer 50 is part of and inseparable from the base material 46 (as opposed to a hardened layer 50 coated on the base material 46). A hardened layer 50 integrated with the base material 46 on one or more surfaces can be distinguished from a hardened layer 50 that is a coating, the latter being a separate material from the base material 46 that is applied to, attached to, or bonded to the surface of the base material 46. The hardened layer 50 may be formed integrally with the base material 46 by surface treating the base material 46 to modify a portion of the base material 46 in the vicinity of its surface, thereby forming the hardened layer 50. Thus, the hardened layer 50 may include a surface treatment layer on the base material 46 of the irregularly shaped bar 12. As shown in Figure 7, in some embodiments, the shaped bar 12 may include a hardened layer 50 and may not have a chromium layer applied to the hardened layer 50 or to the outer surface 32 of the shaped bar 12.

[0043] Treating the surface of the base material 46 to form a hardened layer 50 may involve diffusing one or more chemical components into the interior of the base material 46, and the diffusion of chemical components into the interior of the surface of the base material 46 can change the structure and / or properties of the base material 46 near the outer surface to form the hardened layer 50. Examples of surface treatments for diffusing chemical components into the interior of the surface of the base material 46 include, but are not limited to, nitriding processes, nitrocarburizing processes, borization processes (i.e., diffusing boron into the interior of the surface of the base material 46), or other diffusion-based surface treatments. In a nitriding process, nitrogen may be diffused into the interior of the surface of the base material 46 from one or more nitrogen-containing compounds under high temperature and pressure. The nitriding process may include a gas nitriding process, in which the base material 46 may be exposed to a gas composition containing a gas nitrogen-containing compound, such as nitrogen gas (N2), ammonia gas (NH3), nitrogen plasma, or other nitrogen-containing gases, but is not limited. Alternatively, nitriding may be carried out using a liquid bath containing one or more molten nitrogen-containing salts, such as alkaline cyanates, but is not limited.

[0044] During the soft nitriding process, both nitrogen and carbon may be diffused into the surface interior of the base material 46 from carbon dioxide, carbonates, or other carbon-containing compounds. The soft nitriding process may be a gas-phase or liquid-phase process. In the boration process, boron or a boron-containing compound may be diffused into the surface interior of the base material 46. In some embodiments, the hardened layer 50 integrated with the base material 46 may contain nitride ions. In some embodiments, the hardened layer 50 integrated with the base material 46 may contain nitrogen, carbon, boron, or a combination thereof that has been diffused into the surface interior.

[0045] Surface treatment of the base material 46 to diffuse nitrogen, carbon, boron, or a combination thereof into the interior of the surface of the base material 46 may alter the structure of the base material 46 near the surface. This structural alteration can increase the near-surface hardness of the base material 46 and can lead to the formation of a hardened layer 50 integrated with the base material 46. When the hardened layer 50 is integrated with the base material 46, the outer surface 56 of the hardened layer may harmonize with the outer edge surfaces of the base material 46 (for example, the outer surface 32 of the irregularly shaped bar 12, the first slot surface 34, and / or the second slot surface 36).

[0046] The hardened layer 50 integrated with the base material 46 may have a depth D in the base material 46 which may be sufficient to increase the hardness of the base material 46. In some embodiments, the depth D of the hardened layer may be sufficient to maintain an increased hardness sufficient to reduce wear of the outer surface 56 of the hardened layer while allowing some material to be removed from the outer surface 56 of the hardened layer by electropolishing. Electropolishing may be performed after surface treatment to prepare the outer surface 56 of the hardened layer for a chromium electroplating process to produce the chromium layer 40, if present. The hardened layer 50 integrated with the base material 46 may have a depth D in the base material 46 that is greater than or equal to 5 μm, greater than or equal to 10 μm, greater than or equal to 15 μm, or greater than or equal to 20 μm. Examples of surface treatment processes that form a hardened layer 50 integrated with the base material 46 may include, but are not limited to, hardening processes carried out by BodyCote in the United Kingdom, Nitrex Metal Inc. in Quebec, Canada, Expanite A / S in Cleveland, Ohio, Burlington Engineering, Inc. in Orange County, California, and other hardening processes.

[0047] In some embodiments, the hardened layer 50 integrated with the base material 46 may be formed by a nitriding process that diffuses nitrogen into the interior of the surface of the base material 46. In some embodiments, the hardened layer 50 integrated with the base material 46 may be formed by exposing the base material 46 to a nitrogen-containing environment at a temperature and pressure sufficient to diffuse nitrogen into the interior of the surface of the base material 46. As described above, the nitrogen-containing environment may be a vapor phase (e.g., a gas containing ammonia gas) or a liquid phase (e.g., a bath of molten salt such as an alkaline cyanate). During the nitriding process, the shaped bar 12 may be maintained in an ammonia atmosphere (e.g., ammonia vapor or ammonia bath) at a temperature of about 175°C to about 700°C, for example, 175°C to 250°C, 200°C to 600°C, 200°C to 550°C, or 350°C to 550°C. In some embodiments, the temperature of the nitriding process may be maintained at a temperature lower than the annealing temperature of the base material 46. Annealing of the base material 46 may reduce the strength of the base material 46, which may result in deformation of the shaped bar 12 during assembly or use. In addition, excessive temperature may lead to deformation of the shaped bar 12 during the nitriding process, which may necessitate further processing of the shaped bar 12 or discarding the shaped bar 12 due to non-specified material. In some embodiments, each base material 46 of the shaped bar 12 does not need to be annealed after the nitriding process. The shaped bar 12 may be maintained at the nitriding temperature in an ammonia atmosphere for 5 minutes to 50 hours, for example, 1 hour to 50 hours, or 1 hour to 20 hours. The nitriding process may be carried out at ambient pressure or at a pressure above ambient pressure.

[0048] Referring to Figure 8, as a result of the nitriding process, a compound layer 52 may be formed on the surface 47 of the base material 46. The compound layer 52 may be characterized by a change in the structure of the base material 46 to the epsilon phase (ε phase), the gamma phase (γ phase), or a combination thereof. The compound layer 52 may impart hardness to the base material 46, and thus a hardened layer 50 integrated with the base material 46 may be formed. The compound layer 52 may extend to a depth D within the surface of the base material 46. The depth D of the compound layer 52 may be greater than or equal to 5 μm, greater than or equal to 10 μm, greater than or equal to 15 μm, or greater than or equal to 20 μm. For example, the depth D of the compound layer 52 after nitriding may be 5 μm to 30 μm, 10 μm to 30 μm, or 15 μm to 25 μm. As shown in Figure 8, the nitride ions further diffuse into the matrix 46, and from the compound layer 52 further into the matrix 46 to a diffusion depth D. T A diffusion zone 54 may be formed that extends to a maximum of 0.1 mm or 0.5 mm in diffusion depth D. T It may extend to [a certain point]. The thicknesses of the compound layer 52 and the diffusion zone 54 may be determined in accordance with ASTM B487-85 (2007).

[0049] One or more surfaces of the base material 46, such as the outer surface 32, the first slot surface 34, the second slot surface 36, or a combination thereof, may be subjected to nitriding, soft nitriding, boring, or other surface treatment processes to produce a hardened layer 50 integrated with the base material 46. In some embodiments, the entire shaped bar 12 may be subjected to nitriding, soft nitriding, boring, or other surface treatment processes, so that the entire outer edge surface, including the outer surface 32, the first slot surface 34, and the second slot surface 36, includes a hardened layer 50 integrated with the base material 46. Thus, a diffusion-based surface treatment can produce a hardened layer 50 that covers and extends over the entire outer edge surface of the shaped bar 12.

[0050] A hardened layer 50 integrated with the base material 46, formed by nitriding, soft nitriding, boring, or other surface treatments, may have a Vickers hardness value greater than that of the base material 46. In some embodiments, the hardened layer 50 integrated with the base material 46 may have a Vickers hardness value greater than that of the chromium layer 40. The hardened layer 50 integrated with the base material 46 may have a Vickers hardness greater than or equal to 900HV0.05, greater than or equal to 1000HV0.05, greater than or equal to 1100HV0.05, or greater than or equal to 1200HV0.05. In some embodiments, a hardened layer 50 integrated with the base material 46 and formed by nitriding, soft nitriding, boring, or other surface treatments may have a Vickers hardness value greater than or equal to 1400HV0.05.

[0051] Treating the surface of the irregularly shaped bar 12 by nitriding, soft nitriding, borization, or other treatments may produce a hardened layer 50 having a surface roughness Ra smaller than the surface roughness Ra of the base material 46 before the treatment that forms the hardened layer on the base material 46. In some embodiments, the hardened layer 50 integrated with the base material 46 may have a surface roughness Ra that is at least 0.025 μm, at least 0.030 μm, at least 0.050 μm, or at least 0.100 μm smaller than the surface roughness Ra of the base material 46 before the surface treatment that forms the hardened layer 50. As described above, reducing the roughness of the first slot surface 34 and the second slot surface 36 can reduce the resistance to flow through the slot 20, thereby improving the throughput of the screen cylinder 10 while maintaining separation efficiency.

[0052] Since the hardened layer 50 integrated with the base material 46 is manufactured by modifying the base material 46, the hardened layer 50 integrated with the base material 46, formed by nitriding, soft nitriding, borization, or other surface treatment, may have an electrical conductivity that is within 10% of the electrical conductivity of the base material 46 before the treatment that formed the hardened layer 50. Forming the hardened layer 50 integrated with the base material 46 also does not change the geometry of the irregularly shaped bar 12. Therefore, an irregularly shaped bar 12 having a hardened layer 50 integrated with the surface of the irregularly shaped bar 12 may be replaceable in a standard assembly without making any changes to the support ring 14 or other structures that hold the irregularly shaped bar 12 in place. In addition, the hardened layer 50 integrated with the base material 46 may have good bonding with the chromium layer 40 and may exhibit reduced corrosion properties.

[0053] Referring now to Figure 9, in some embodiments, the hardened layer 50 may include a hard coating 60 applied to one or more surfaces of the base material 46 of the shaped bar 12. The hard coating 60 may be applied to the outer surface 32, the first slot surface 34, the second slot surface 36, or a combination thereof. In some embodiments, the hardened layer 50 may be a hard coating 60 applied to the entire outer edge surface of the shaped bar 12, including the outer surface 32, the first slot surface 34, and the second slot surface 36. In some embodiments, the hard coating 60 of the hardened layer 50 may be applied to at least 20%, at least 50%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, or at least 99% of the surface area of ​​the outer edge surface of the shaped bar 12. In some embodiments, the hard coating 60 of the hardened layer 50 may be applied to at least the first slot surface 34 and the second slot surface 36.

[0054] The hard coating 60 of the hardened layer 50 may be applied to the base material 46 by known coating or spraying methods, for example, but not limited to, high-velocity flame spraying (HVOF), plasma spraying, laser spraying, chemical vapor deposition (CVD), physical vapor deposition (PVD), atomic layer deposition (ALD), electroplating, electroless plating (e.g., electroless nickel plating), ceramic coating, diamond-like carbon (DLC) coating, other coating methods, or combinations thereof. In some embodiments, the hard coating 60 may be applied using the HVOF process. The hard coating 60 may contain compounds having a hardness exceeding that of the base material 46. Examples of the hard coating 60, but not limited to, tungsten carbide, chromium carbide, titanium nitride, chromium nitride, electroless nickel plating, ceramic coating, alumina, other hard coating materials, or combinations thereof. In some embodiments, the hard coating 60 may be a tungsten carbide coating. In some embodiments, the hardened layer 50 including the hard coating 60 may be a titanium nitride or chromium nitride coating applied using a PVD process. In some embodiments, the hard coating 60 of the hardened layer 50 may be a nickel layer applied using an electroless plating process. In some embodiments, the hard coating 60 may be a ceramic coating formed by applying a thin film of ceramic paint to one or more surfaces of the shaped bar 12 and firing the shaped bar at a temperature sufficient to cure the ceramic coating and bond the ceramic coating to the base material 46.

[0055] The hard coating 60 may have a thickness greater than or equal to 5 μm, greater than or equal to 10 μm, greater than or equal to 15 μm, or greater than or equal to 20 μm. The hard coating 60 may have a thickness less than or equal to 300 μm, less than or equal to 250 μm, less than or equal to 200 μm, less than or equal to 100 μm, or less than or equal to 50 μm. The hard coating 60 may have a thickness of 5 μm to 300 μm, 5 μm to 100 μm, or 10 μm to 50 μm. The hard coating 60 may have a Vickers hardness value sufficient to reduce or prevent wear of the first slot surface 34 and / or the second slot surface 36. The hard coating 60 may have a Vickers hardness value greater than that of the base material 46. In some embodiments, the hard coating 60 may have a Vickers hardness value greater than that of the chromium layer 40. The hard coating 60 may have a Vickers hardness greater than or equal to 500HV0.05, greater than or equal to 700HV0.05, greater than or equal to 900HV0.05, greater than or equal to 1000HV0.05, or greater than or equal to 1100HV0.05.

[0056] Referring again to Figure 5, as previously stated herein, in some embodiments the shaped bar 12 may include a chromium layer 40 on the outer surface 32 of the shaped bar 12 or installed in the hardened layer 50. The chromium layer 40 can protect the outer surface 32 of the shaped bar 12 from wear and damage caused by pressure pulsations from the rotor for removing excessive solid foreign matter from the slotted cylindrical wall 16 of the screen cylinder 10. In some embodiments, the outer surface 32 of each of the multiple shaped bars 12 may include the hardened layer 50, and the chromium layer 40 may be installed in the hardened layer 50. The chromium layer 40 may be formed on one or more portions of the first slot surface 34, the second slot surface 36, or both. The chromium layer 40 may be deposited on the first slot surface 34 and the second slot surface 36, overlaid on the hardened layer 50.

[0057] The chromium layer 40 may have an average thickness sufficient to protect the outer surface 32 of the shaped bar 12 and withstand pressure pulsations from the rotor. In some embodiments, the chromium layer 40 may have an average thickness greater than or equal to 10 μm, greater than or equal to 20 μm, greater than or equal to 30 μm, or greater than or equal to 40 μm. The chromium layer 40 may have its maximum thickness on the outer surface 32 of the shaped bar 12. The thickness of each chromium layer 40 on the shaped bar 12 may decrease from each outer surface 32 of the shaped bar 12 toward the mounting end 30. The chromium layer 40 may have a Vickers hardness value of about 900 HV 0.05 to about 1000 HV 0.05. In some embodiments, the shaped bar 12 may have a hardened layer 50 without the chromium layer 40. In some embodiments, the shaped bar 12 may be substantially chromium-free, for example, having less than 5% or 5% chromium on the outer edge surface of the shaped bar 12.

[0058] A method for manufacturing a hardened shaped bar 12 for a screen cylinder 10 may include providing a shaped bar 12 including a mounting end 30 and an outer surface 32 facing in the opposite direction from the mounting end 30. The shaped bar 12 may include a first slot surface 34 extending from the outer surface 32 to the mounting end 30, and a second slot surface 36 extending from the outer surface 32 to the mounting end 30 on the opposite side of the first slot surface 34. The method may further include forming a hardened layer 50 on or integrated with at least a portion of the first slot surface 34, the hardened layer 50 having a Vickers hardness value greater than that of the base material 46. The hardened layer 50 may have a Vickers hardness value greater than or equal to 500HV0.05, greater than or equal to 900HV0.05, greater than or equal to 1000HV0.05, greater than or equal to 1100HV0.05, or greater than or equal to 1200HV0.05. The method may further include depositing a chromium layer 40 on at least the outer surface 32 of the irregularly shaped bar 12 or on the hardened layer 50. In some embodiments, the method may include forming the hardened layer 50 on a portion of the outer surface 32, a portion of the second slot surface 36, or both, in addition to the first slot surface 34.

[0059] In some embodiments, forming the hardened layer 50 may involve surface treating at least the first slot surface 34 of the shaped bar 12 to diffuse one or more chemical compounds into the base material 46 on the first slot surface 34. In some embodiments, the method may involve surface treating the entire outer edge surface of the shaped bar 12 to form the hardened layer 50 on the entire outer edge surface of the shaped bar 12, including the outer surface 32, the first slot surface 34, and the second slot surface 36. The method may involve forming the hardened layer 50 on at least 25%, at least 50%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, or at least 99% of the surface area of ​​the outer edge surface of the shaped bar 12. The surface treatment may involve contacting at least a portion of the shaped bar 12 with a nitrogen-containing gas at a temperature lower than the annealing temperature of the base material 46 and at a pressure sufficient to diffuse nitrogen or a nitrogen-containing compound into the base material 46. The nitrogen-containing gas may include nitrogen gas, ammonia, or other nitrogen gases. In some embodiments, the surface treatment for forming the hardened layer 50 integrated with the base material 46 may include a nitriding process. The nitriding process can be carried out according to any of the operating parameters described herein.

[0060] In some embodiments, forming the hardened layer 50 may involve applying a hard coating 60 to at least the first slot surface 34 of the irregularly shaped bar 12. Applying the hard coating 60 may involve any of the coating processes described herein, and the hard coating 60 may be any of the materials described herein. In some embodiments, applying the coating to at least the first slot surface 34 may involve a thermal spraying process. In some embodiments, the thermal spraying process may include a high-velocity tungsten carbide flame spraying (HVOF) process.

[0061] A method for manufacturing the irregularly shaped bar 12 may include polishing the irregularly shaped bar 12 to prepare it for electroplating the chromium layer 40 onto the hardened layer 50. Polishing may include processes for polishing metal components known in the art. The polishing step may be sufficient to prepare the surface for coating with the chromium layer 40, but not to the extent that the hardened layer 50 is rendered ineffective or completely removed.

[0062] A method for producing a shaped bar 12 may include forming a hardened layer 50 on the outer surface 32 of the shaped bar 12, and depositing a chromium layer 40 on the outer surface 56 of the hardened layer 50 formed on the outer surface 32 of the shaped bar 12. As described above, the method may include a polishing step between forming the hardened layer 50 and depositing the chromium layer 40. The chromium layer 40 may be applied by an electroplating process.

[0063] As described herein, the screen cylinder 10, including the shaped bar 12 having a hardened layer 50, may be used in the papermaking industry to process solid suspensions of cellulose or other fibers in pulp, as described herein. However, the screen cylinder 10 is not limited to use in the pulp and papermaking industry. For example, the screen cylinder 10 of this disclosure, having the hardened shaped bar 12, may be used in mining and exploration applications, food preparation and processing operations, water treatment processes, coating operations, and other industries to screen solid suspensions and / or slurries to remove excessive solid impurities.

[0064] Referring again to Figure 1, in some embodiments, a method for removing excessive solid foreign matter from a slurry or solid suspension may include bringing the slurry or solid suspension into contact with a screen cylinder 10. The screen cylinder 10 may include a plurality of shaped bars 12 connected to at least one support ring 14 and aligned longitudinally. The shaped bars 12 may have any of the features or properties described herein. Referring to Figure 5, in some embodiments, each of the plurality of shaped bars 12 may include an outer surface 32 facing outward from at least one support ring 14, a first slot surface 34 extending from the outer surface 32 of the shaped bar 12 to a mounting end 30 opposite the outer surface 32, and a second slot surface 36 extending from the outer surface 32 of the shaped bar 12 to the mounting end 30, opposite the first slot surface 34. As described above, each of the shaped bars may include a hardened layer 50 integrated with or installed on at least a portion of the first slot surface 34 of each shaped bar 12, the hardened layer 50 having a Vickers hardness value greater than or equal to the base material 46, for example, greater than or equal to 500HV0.05, greater than or equal to 900HV0.05, greater than or equal to 1000HV0.05, greater than or equal to 1100HV0.05, or greater than or equal to 1200HV0.05. The first and second slot surfaces of adjacent pairs of shaped bars 12 (for example, pairs of directly adjacent shaped bars 12) define a plurality of slots in the screen cylinder. Contact between the slurry or solid suspension and the screen cylinder may allow at least a portion of the slurry or solid suspension to pass through the slots 20. The method may further include recovering an acceptable portion of the slurry or solid suspension from a plurality of slots 20 of the screen cylinder 10. In some embodiments, the shaped bar 12 may further include a chromium layer 40 on the outer surface 32 of the shaped bar 12 or on the hardened layer 50. In some embodiments, the method may further include removing at least a portion of solid foreign matter from the outer surface 32 of the plurality of shaped bars 12. [Examples]

[0065] Embodiments of this disclosure will become even more apparent from the following embodiments, but they shall not be construed as limiting the embodiments of the claims described herein and / or herein.

[0066] Example 1 Multiple stainless steel shaped bars of a screen cylinder were subjected to a soft nitriding process to produce a hardened layer integrated with the surface of the shaped bars. The base material of the shaped bars in Example 1 was 316L stainless steel. The soft nitriding process was achieved by immersing the shaped bars in a molten salt bath maintained at a temperature in the range of 370°C to 540°C for a time sufficient for the hardened layer to form. The salt bath contained cyanate ions to provide nitrogen and carbonate ions to provide carbon. The soft nitriding process produced a compound layer and a diffusion zone extending further into the base material from the compound layer.

[0067] In Examples 1 and 2, the thicknesses of the compound layer and diffusion zone of the nitrided samples were measured according to ASTM B487-85 (2007). These thicknesses were measured at a magnification of 1000. Vickers hardness values ​​were measured according to ASTM E384-11e1. For each diffusion zone of the nitrided bar, the Vickers hardness (HV) was measured on the cross-section of the shaped bar using an indentation load of 0.05 kgf (approximately 0.49 N). The compound layer was hardened by lightly polishing the outer surface of the shaped bar with a 1 μm abrasive, and then the hardness test was performed on the outer surface. The indentation load was also 0.05 kgf (approximately 0.49 N). The Vickers hardness values ​​were further converted to approximate Rockwell hardness (HRC) values ​​using equation X1.1.1 of ASTM E140-12be1. The average thickness of the compound layer and the diffusion layer of the cured shaped bar of Example 1, the average Vickers hardness, and the average HRC are provided in Table 1 below.

[0068] [Table 1]

[0069] In addition, the irregularly shaped bar from Example 1 was subjected to a welding test to evaluate the joint of the weld between the irregularly shaped bar and the end flange of the screen cylinder. A portion of the irregularly shaped bar from Example 1 was welded to a stainless steel flange. No problems were observed with the joint of the weld.

[0070] A corrosion test was also performed on the irregularly shaped bar of Example 1. In the first corrosion test, a subset of the irregularly shaped bar of Example 1 was placed in water for 20 days. After immersion in water for 1 day, no corrosion was observed in the sample. After 20 days, the portion of the irregularly shaped bar of Example 1 that had been immersed in water showed a layer of corrosion on its outer surface. In addition, a second subset of the irregularly shaped bar of Example 1 was exposed to ambient air. After 430 days, the irregularly shaped bar showed a small area of ​​corrosion on its outer surface.

[0071] Example 2 A second set of stainless steel shaped bars from the screen cylinder were subjected to a soft nitriding process to produce a hardened layer integrated with the surface of the shaped bars. The base material of the shaped bars in Example 1 was 316L stainless steel. The soft nitriding process was carried out by immersing the shaped bars in a molten salt bath maintained at a temperature of 370°C to 540°C for a time sufficient for the hardened layer to form. The salt bath contained cyanate ions to provide nitrogen and carbonate ions to provide carbon. The soft nitriding process produced a compound layer and a diffusion zone extending further into the base material from the compound layer. The thickness of the diffusion zone and compound layer, Vickers hardness, and HRC of each sample shaped bar were measured according to the method described above in Example 1. The average thickness of the compound layer and diffusion layer, average Vickers hardness, and average HRC of the hardened shaped bars in Example 2 are provided in Table 2 below.

[0072] [Table 2]

[0073] The irregularly shaped bar from Example 2 was also subjected to a welding test to evaluate the joint of the weld between the irregularly shaped bar and the end flange of the screen cylinder. A portion of the irregularly shaped bar from Example 2 was welded to a stainless steel flange. No problems were observed with the joint of the weld.

[0074] A corrosion test was also performed on the irregularly shaped bar of Example 2. In the first corrosion test, a subset of the irregularly shaped bar of Example 2 was placed in water for 20 days. After immersion in water for 2 days, no corrosion was observed in the sample. After 20 days, the portion of the irregularly shaped bar of Example 2 that had been immersed in water showed a layer of corrosion on its outer surface. In addition, a second subset of the irregularly shaped bar of Example 2 was exposed to ambient air. After 430 days, the irregularly shaped bar showed a small area of ​​corrosion on its outer surface.

[0075] Example 3 In Example 3, several other stainless steel shaped bars of the screen cylinder were subjected to a nitriding process carried out according to the NANO-S® nitriding process provided by Nitrex Metals Inc. of Quebec, Canada, to produce a hardened layer integrated with the surface of the shaped bars. The nitriding process produced a compound layer and a diffusion zone extending further into the base material from the compound layer. The thickness of the diffusion zone and compound layer and the Vickers hardness of each sample shaped bar in Example 3 were measured according to the method described above in Example 1, and the results are provided in Table 3 below.

[0076] [Table 3]

[0077] In addition, the surface roughness Ra of the outer surface of the hardened compound layer was measured to be 0.10 μm, which is comparable to the surface roughness of a bare, untreated irregularly shaped bar with a surface roughness Ra of 0.09 μm.

[0078] Example 4 In Example 4, multiple stainless steel shaped bars were subjected to a tungsten carbide HVOF process to coat the shaped bars with a tungsten carbide coating. Therefore, in Example 4, the hardened layer was a hard coating containing tungsten carbide.

[0079] The thickness of the hard coating in Example 4 was measured according to ASTM B487-85 (2007). In Example 4, the thickness was measured at a magnification of 500. The Vickers hardness value was measured according to ASTM E384-11e1. Vickers hardness (HV) was measured on the cross section of the shaped bar using an indentation load of 0.1 kilograms-force (kgf) (approximately 0.98 N). Hardness testing was performed in areas of the hard coating that were free from large pores or shrinkage. The Vickers hardness values ​​were further converted to approximate Rockwell hardness (HRC) values ​​using formula X1.1.1 of ASTM E140-12be1. The average thickness, average Vickers hardness, and average HRC of the hard coating on the shaped bar in Example 4 are provided in Table 4 below.

[0080] [Table 4]

[0081] The irregularly shaped bars of Example 4, which had a tungsten carbide coating, exhibited a higher average hardness compared to the irregularly shaped bars of Examples 1 and 2, which had a hardened layer integrated with the base material. However, the irregularly shaped bars of Example 4, which had a tungsten carbide coating applied with HVOF, were observed to exhibit a higher surface roughness than the irregularly shaped bars of Examples 1 and 2, in which the hardened layer was integrally formed with the base material using a nitriding process. In addition, the thickness of the hardened layer (i.e., the tungsten carbide coating) of the irregularly shaped bars of Example 4 was not as consistent as the thickness of the hardened layer of the irregularly shaped bars of Examples 1 and 2.

[0082] Furthermore, bonding tests were performed on the irregularly shaped bar of Example 4 at the interface between the base material and the tungsten carbide coating using the interface indentation method. In the interface indentation method, Vickers indentation was applied at the interface between the base material and the tungsten carbide coating using loads of 0.1 kgf (approximately 0.98 N) and 0.5 kgf (approximately 4.90 N). In response to the interface indentation test, no visible cracks were observed at the interface with a load of 0.1 kgf (approximately 0.98 N), but some small cracks were observed at the interface between the base material and the tungsten carbide coating with an indentation load of 0.5 kgf (approximately 4.90 N).

[0083] Example 5 In Example 5, multiple irregularly shaped bars from Example 4, having a tungsten carbide coating applied with HVOF, were electroplated with chromium to produce a chromium layer. The chromium layer was applied over the tungsten carbide coating. In sample 5A, the electroplating process was carried out for a longer period, resulting in a thicker chromium layer. In sample 5B, the electroplating time was shortened, resulting in a thinner chromium layer. The average thickness of the tungsten carbide coating was determined. Due to inconsistencies in the electroplating process, the thickness of the chromium layer was measured for samples 5A and 5B at the thickest, thinnest, and intermediate thickness regions of the chromium layer. In addition, the Vickers hardness of the tungsten carbide coating was measured according to the method described herein. The thickness and Vickers hardness values ​​for samples 5A and 5B are provided in Table 5 below.

[0084] [Table 5]

[0085] Comparative Example 6 In Comparative Example 6, the Vickers hardness values ​​of several untreated shaped bars, each with a 316L stainless steel base material and neither a hardened layer nor a chromium layer, were measured. The Vickers hardness values ​​of the shaped bars in Comparative Example 6 are provided in Table 6 below.

[0086] Comparative Example 7 In Comparative Example 7, multiple irregularly shaped bars were electroplated with chromium to form a chromium layer, and there was no hardened layer between the base material and the chromium layer. The Vickers hardness values ​​of the irregularly shaped bars of Comparative Example 7 were measured according to the test method described above in this specification. The Vickers hardness values ​​of the irregularly shaped bars of Comparative Example 7, which have a chromium layer but no hardened layer, are provided in Table 6. Due to variations in the thickness of the chromium layer applied by electroplating, the Vickers hardness values ​​of each chromium layer of the irregularly shaped bars of Comparative Example 7 were determined for a first region with a thicker chromium layer, a second region with a chromium layer of intermediate thickness, and a third region with a thinner chromium layer.

[0087] [Table 6]

[0088] All hardened shaped bars in Examples 1-5 exhibited an average Vickers hardness higher than that of Comparative Example 6, which was an untreated shaped bar. All hardened shaped bars in Examples 1 and 3-5 had an average Vickers hardness comparable to or exceeding that of the shaped bar in Comparative Example 7, which was coated with a chromium coating. Therefore, hardened shaped bars cured by the methods disclosed herein can have a hardness substantially higher than that of the base material and comparable to or exceeding that of a shaped bar with only a chromium layer deposited.

[0089] One aspect of the present disclosure may relate to a screen cylinder comprising a plurality of shaped bars, which are aligned longitudinally and connected at the mounting ends of the plurality of shaped bars to at least one support ring. Each of the plurality of shaped bars may include an outer surface facing outward from at least one support ring, a first slot surface extending from the outer surface of the shaped bar to the mounting end opposite the outer surface, and a second slot surface extending from the outer surface of the shaped bar to the mounting end, opposite the first slot surface. The first slot surface of one shaped bar and the second slot surface of another immediately adjacent shaped bar may define a slot. Each of the plurality of shaped bars may further include a hardened layer integrated with or installed on at least a portion of the first slot surface of the shaped bar. The hardened layer may have a Vickers hardness value greater than or equal to 500HV0.05, as determined in accordance with ASTM E384-11e1.

[0090] Embodiment (2) of the present disclosure may include embodiment (1), wherein the cured layer may be installed on a portion of each second slot surface, outer surface, or both of the irregularly shaped bar.

[0091] Aspects of the present disclosure may include either aspect (1) or (2), wherein the cured layer may be provided on the entire outer surface of each of the irregularly shaped bars, and the entire outer surface includes at least the outer surface, a first slot surface, and a second slot surface.

[0092] Aspect (4) of the present disclosure may include any one of aspects (1) to (3), wherein the cured layer has an outer surface of the cured layer having a topography in which the dimensions are constant to a tolerance of less than or equal to 9 micrometers (μm).

[0093] Aspect (5) of the present disclosure may include any one of aspects (1) to (4), wherein the cured layer may have a Vickers hardness value greater than or equal to 900HV0.05, as determined in accordance with ASTM E384-11e1.

[0094] Aspect (6) of the present disclosure may include any one of aspects (1) to (5), wherein the hardened layer may have the same electrical conductivity as the base material of the plurality of irregularly shaped bars.

[0095] Aspect (7) of the present disclosure may include any one of aspects (1) to (6), wherein the base material of each of the multiple irregularly shaped bars may include stainless steel.

[0096] Aspect (8) of the present disclosure may include any one of aspects (1) to (7), and the base material of each of the multiple irregularly shaped bars may not be annealed.

[0097] Aspect (9) of the present disclosure may include any one of aspects (1) to (8), further comprising a chromium layer placed on the outer surface of a shaped bar or on a hardened layer.

[0098] Aspect (10) of the present disclosure may include aspect (9), wherein the thickness of each chromium layer of the shaped bar may decrease from each outer surface of the shaped bar toward the mounting end.

[0099] Aspect (11) of the present disclosure may include any one of aspects (1) to (10), wherein the hardened layer may include a surface treatment layer of the base material of the irregularly shaped bar.

[0100] Aspect (12) of the present disclosure may include aspect (11), wherein the depth of the surface treatment layer on the base material may be greater than or equal to 5 μm.

[0101] Aspect (13) of the present disclosure may include either aspect (11) or (12), wherein the surface treatment layer may contain at least nitride ions.

[0102] Aspect (14) of the present disclosure may include any one of aspects (1) to (8), wherein the outer surface of each of the multiple irregularly shaped bars may include a hardened layer, and a chromium layer is provided on the hardened layer.

[0103] Aspect (15) of the present disclosure may include any one of aspects (1) to (10), wherein the hardened layer may be a hard coating applied to at least a portion of the surface of the first slot of the irregularly shaped bar.

[0104] Aspect (16) of the present disclosure may include aspect (15), wherein the thickness of the hard coating is greater than or equal to 5 μm, or between 5 μm and 300 μm.

[0105] Aspect (17) of the present disclosure may include either aspect (15) or (16), wherein the hard coating may include tungsten carbide, chromium carbide, titanium nitride, chromium nitride, electroless plated nickel, ceramic coating, alumina, or a combination thereof. The hard coating may be a tungsten carbide coating. The hard coating of the hardened layer may be a titanium nitride or chromium nitride coating applied by a PVD process. The hard coating of the hardened layer may be a nickel layer applied using an electroless plating process. The hard coating may be a ceramic coating.

[0106] Aspect (18) of the present disclosure may include any one of aspects (1) to (17), wherein the screen cylinder may function to separate solid foreign matter from a solid suspension.

[0107] Aspect (19) of the present disclosure relates to a shaped bar for a screen cylinder for separating solid foreign matter from a solid suspension. The shaped bar may include an outer surface provided at a mounting end and the opposite end of the mounting end, a first slot surface extending from the outer surface of the shaped bar to the mounting end, a second slot surface extending from the outer surface to the mounting end on the opposite side of the first slot surface, and a hardened layer integrated with or provided thereon on at least a portion of the first slot surface, a portion of the second slot surface, or both. The hardened layer may have a Vickers hardness value greater than or equal to 500HV0.05, as determined in accordance with ASTM E384-11e1.

[0108] Aspect (20) of the present disclosure may include aspect (19), in which, when a plurality of irregularly shaped bars are arranged longitudinally and adjacent to each other, a first slot surface of one irregularly shaped bar and a second slot surface of another immediately adjacent irregularly shaped bar may define a slot.

[0109] Aspect (21) of the present disclosure may include either aspect (19) or (20), wherein the cured layer may be applied to the entire outer edge surface of each of the irregularly shaped bars. The entire outer edge surface may include at least 80% of the outer surface, the first slot surface, and the second slot surface.

[0110] Aspect (22) of the present disclosure may include any one of aspects (19) to (21), wherein the cured layer has an outer surface of the cured layer having a topography in which the dimensions are constant to a tolerance of less than or equal to 9 micrometers (μm).

[0111] Aspect (23) of the present disclosure may include any one of aspects (19) to (22), wherein the cured layer may have a Vickers hardness value greater than or equal to 900HV0.05, as determined in accordance with ASTM E384-11e1.

[0112] Aspect (24) of the present disclosure may include any one of aspects (19) to (23), wherein the hardened layer may have the same electrical conductivity as the base material of the plurality of irregularly shaped bars.

[0113] Aspect (25) of the present disclosure may include any one of aspects (19) to (24), wherein the base material of each of the multiple irregularly shaped bars may include stainless steel.

[0114] Aspect (26) of the present disclosure may include any one of aspects (19) to (25), wherein the base material of each of the multiple irregularly shaped bars does not need to be annealed.

[0115] Aspect (27) of the present disclosure may include any one of aspects (19) to (26), and may further include a chromium layer installed on the outer surface or on the hardened layer.

[0116] Aspect (28) of the present disclosure may include aspect (27), wherein the thickness of the chromium layer may decrease from the outer surface of the irregularly shaped bar toward the mounting end.

[0117] Aspect (29) of the present disclosure may include any one of aspects (19) to (28), wherein the hardened layer may include surface treatment of the base material to a certain depth within the base material of the irregularly shaped bar.

[0118] Aspect (30) of the present disclosure may include aspect (29), wherein the depth of the cured layer may be greater than or equal to 5 μm.

[0119] Aspect (31) of the present disclosure may include either aspect (29) or (30), wherein the cured layer may contain at least nitride ions.

[0120] Aspect (32) of the present disclosure may include any one of aspects (19) to (28), wherein the outer surface may include a hardened layer, and a chromium layer is installed on top of the hardened layer.

[0121] Aspect (33) of the present disclosure may include any one of aspects (19) to (28), wherein the hardened layer may be a hard coating applied to the base material.

[0122] Aspect (34) of the present disclosure may include aspect (33), wherein the thickness of the hard coating is greater than or equal to 5 μm, or between 5 μm and 300 μm.

[0123] Aspect (35) of the present disclosure may include either aspect (33) or (34), wherein the hard coating may include tungsten carbide, chromium carbide, titanium nitride, chromium nitride, electroless plated nickel, ceramic coating, alumina, or a combination thereof. The hard coating may be a tungsten carbide coating. The hard coating of the hardened layer may be a titanium nitride or chromium nitride coating applied by a PVD process. The hard coating of the hardened layer may be a nickel layer applied using an electroless plating process. The hard coating may be a ceramic coating.

[0124] Aspect (36) of the present disclosure may include any one of aspects (19) to (35) and may relate to a screen cylinder including any of the irregularly shaped bars in aspects (19) to (35).

[0125] Aspect (37) of the present disclosure may include aspect (36), wherein the screen cylinder includes a plurality of shaped bars, which are aligned longitudinally and connected at the mounting ends of the plurality of shaped bars to at least one support ring.

[0126] Aspects (38) of the present disclosure relate to a method for producing a hardened shaped bar for a screen cylinder. The method may include providing a shaped bar which includes a mounting end and an outer surface facing the opposite direction from the mounting end, a first slot surface extending from the outer surface of the shaped bar to the mounting end, and a second slot surface extending from the outer surface to the mounting end on the opposite side of the first slot surface. The method may further include forming a hardened layer on or integrated with at least a portion of the first slot surface, the hardened layer having a Vickers hardness value greater than or equal to 500HV0.05, as determined in accordance with ASTM E384-11e1.

[0127] Aspect (39) of the present disclosure may include aspect (38), further comprising depositing a chromium layer on the outer surface of the shaped bar or on the hardened layer.

[0128] Aspect (40) of the present disclosure may include either aspect (38) or (39), which includes forming a cured layer on the outer surface, the second slot surface, or a portion of both.

[0129] Aspect (41) of the present disclosure may include any one of aspects (38) to (40), wherein forming a hardened layer may include subjecting at least the first slot surface of the irregularly shaped bar to a surface treatment that diffuses one or more chemical compounds into the base material of the first slot surface.

[0130] Aspect (42) of the present disclosure may include aspect (41), wherein the surface treatment may include contacting at least a portion of the shaped bar with a nitrogen-containing gas or nitrogen-containing liquid bath at a temperature lower than the annealing temperature of the base material and at a pressure sufficient to diffuse nitrogen or a nitrogen-containing compound into the base material.

[0131] Aspect (43) of the present disclosure may include any one of aspects (38) to (40), and forming a hardened layer may include applying a coating to at least the first slot surface of the irregularly shaped bar.

[0132] Aspect (44) of the present disclosure may include aspect (43), which may include a heat-blasting process for applying a coating to at least the first slot surface.

[0133] Aspect (45) of the present disclosure may include aspect (44), wherein the thermal spraying process may include a high-velocity tungsten carbide flame spraying (HVOF) process.

[0134] Aspect (46) of the present disclosure may include aspect (43), in which forming a hardened layer may include applying a thin film of ceramic coating to one or more surfaces of a shaped bar, and firing the shaped bar at a temperature sufficient to form a ceramic coating and bond the ceramic coating to the base material of the shaped bar.

[0135] Aspect (47) of the present disclosure may include any one of aspects (38) to (46), and includes forming a hardened layer on the outer surface of a shaped bar, and depositing a chromium layer on the outer surface of the hardened layer formed on the outer surface of the shaped bar.

[0136] Aspect (48) of the present disclosure may include aspect (47), wherein the thickness of the chromium layer may decrease from the outer surface of the irregularly shaped bar toward the mounting end.

[0137] Aspects (49) of the present disclosure relate to a method for removing solid foreign matter from a solid suspension. The method may include bringing the solid suspension into contact with a screen cylinder. The screen cylinder may include a plurality of shaped bars connected to at least one support ring and aligned longitudinally. Each of the plurality of shaped bars may include an outer surface facing outward from at least one support ring, a first slot surface extending from the outer surface of the shaped bar to a mounting end opposite the outer surface, a second slot surface extending from the outer surface of the shaped bar to the mounting end opposite the first slot surface, and a hardened layer integrated with or installed thereon on at least a portion of each of the first slot surfaces of the shaped bar. The hardened layer may have a Vickers hardness value greater than or equal to 500HV0.05, as determined in accordance with ASTM E384-11e1. The first and second slot surfaces of adjacent pairs of irregularly shaped bars may define a plurality of slots in the screen cylinder, and contact between the solid suspension and the screen cylinder may allow at least a portion of the solid suspension to pass through the slots. The method may further include recovering an acceptable amount of solid suspension from the plurality of slots in the screen cylinder.

[0138] Aspect (50) of the present disclosure may include aspect (49), further comprising removing at least a portion of solid foreign matter from the outer surface of a plurality of irregularly shaped bars.

[0139] Aspect (51) of the present disclosure may include either aspect (49) or (50), where each of the multiple shaped bars may include a chromium layer placed on the outer surface of the shaped bar or on the hardened layer.

[0140] Aspect (52) of the present disclosure may include any one of aspects (49) to (51), wherein the hardened layer may include a surface treatment layer of the base material of the irregularly shaped bar.

[0141] Aspect (53) of the present disclosure may include any one of aspects (49) to (51), wherein the hardened layer may be a hard coating applied to at least a portion of the first slot surface of the irregularly shaped bar.

[0142] Various embodiments of the shaped bar 12 of the screen cylinder 10, and methods for manufacturing and using the shaped bar 12, are described herein, but it should be understood that each of these embodiments and techniques may be used separately from or in connection with one or more embodiments and techniques. It will be obvious to those skilled in the art that various modifications and variations can be made to the embodiments described herein without departing from the spirit and scope of the claims. Accordingly, this specification will cover various modifications and variations of the embodiments described herein, provided that such modifications and variations are within the scope of the appended claims and their equivalents.

[0143] Preferred embodiments of the present invention are described below in separate sections.

[0144] Embodiment 1 In a screen cylinder, Multiple irregularly shaped bars, which are aligned in the longitudinal direction and connected to at least one support ring at the mounting end of the multiple irregularly shaped bars, Includes, Each of the aforementioned multiple irregularly shaped bars is Outer surface facing outward from at least one of the support rings; A first slot surface extending from the outer surface of the irregularly shaped bar to the mounting end on the opposite side of the outer surface; A second slot surface, on the opposite side of the first slot surface, extending from the outer surface of the shaped bar to the mounting end, wherein the first slot surface of one shaped bar and the second slot surface of another immediately adjacent shaped bar define a slot; and A hardened layer integrated with or installed on at least a portion of the surface of the first slot of the deformed bar, having a Vickers hardness value greater than or equal to 500HV0.05 as determined in accordance with ASTM E384-11e1, A screen cylinder, including a screen cylinder.

[0145] Embodiment 2 The screen cylinder according to Embodiment 1, wherein the hardened layer is installed on a portion of each of the second slot surfaces, the outer surface, or both of the irregularly shaped bars.

[0146] Embodiment 3 The screen cylinder according to Embodiment 1 or 2, wherein the hardened layer is provided on the entire outer edge surface of each of the irregularly shaped bars, and the entire outer edge surface includes at least the outer surface, the first slot surface, and the second slot surface.

[0147] Embodiment 4 The screen cylinder according to any one of Embodiments 1 to 3, wherein the cured layer has an outer surface of the cured layer having a topography in which the dimensions are constant to a tolerance of less than or equal to 9 micrometers (μm).

[0148] Embodiment 5 A screen cylinder according to any one of Embodiments 1 to 4, wherein the hardened layer has a Vickers hardness value greater than or equal to 900HV0.05 when determined in accordance with ASTM E384-11e1.

[0149] Embodiment 6 The screen cylinder according to any one of Embodiments 1 to 5, wherein the hardened layer has the same electrical conductivity as the base material of the plurality of irregularly shaped bars.

[0150] Embodiment 7 A screen cylinder according to any one of Embodiments 1 to 6, wherein the base material of each of the plurality of irregularly shaped bars is stainless steel.

[0151] Embodiment 8 A screen cylinder according to any one of Embodiments 1 to 7, wherein the base material of each of the plurality of irregularly shaped bars is not annealed.

[0152] Embodiment 9 A screen cylinder according to any one of Embodiments 1 to 8, further comprising a chromium layer installed on the outer surface of the irregularly shaped bar or on the hardened layer.

[0153] Embodiment 10 The screen cylinder according to Embodiment 9, wherein the thickness of the chrome layer on each of the irregularly shaped bars decreases from the outer surface of each of the irregularly shaped bars toward the mounting end.

[0154] Embodiment 11 A screen cylinder according to any one of Embodiments 1 to 10, wherein the outer surface of each of the plurality of irregularly shaped bars includes the hardened layer, and a chromium layer is installed on the hardened layer.

[0155] Embodiment 12 The screen cylinder according to any one of embodiments 1 to 11, wherein the hardened layer is a hard coating applied to at least a portion of the surface of the first slot of the irregularly shaped bar.

[0156] Embodiment 13 The screen cylinder according to any one of Embodiments 1 to 11, wherein the thickness of the hard coating is greater than or equal to 5 μm, or is between 5 μm and 300 μm.

[0157] Embodiment 14 The screen cylinder according to any one of Embodiments 12 or 13, wherein the hard coating includes tungsten carbide, chromium carbide, titanium nitride, chromium nitride, electroless nickel plating, ceramic coating, alumina, or a combination thereof.

[0158] Embodiment 15 The screen cylinder according to any one of embodiments 12 to 14, wherein the hard coating includes a ceramic coating.

[0159] Embodiment 16 The screen cylinder according to any one of Embodiments 1 to 11, wherein the hardened layer includes a surface treatment layer for the base material of the irregularly shaped bar.

[0160] Embodiment 17 The screen cylinder according to Embodiment 16, wherein the depth of the surface treatment layer of the base material is greater than or equal to 5 μm.

[0161] Embodiment 18 The screen cylinder according to any one of Embodiments 16 or 17, wherein the surface treatment layer contains at least nitride ions.

[0162] Embodiment 19 A screen cylinder according to any one of Embodiments 1 to 18, which functions to separate solid foreign matter from a solid suspension.

[0163] Embodiment 20 In a method for removing solid foreign matter from a solid suspension, A step of bringing a solid suspension into contact with a screen cylinder including a plurality of shaped bars connected to at least one support ring and aligned longitudinally, wherein each of the plurality of shaped bars is Outer surface facing outward from at least one of the support rings; A first slot surface extending from the outer surface of the irregularly shaped bar to the mounting end opposite the outer surface; A second slot surface, on the opposite side of the first slot surface, extending from the outer surface of the irregularly shaped bar to the mounting end; and A hardened layer integrated with or installed on at least a portion of the surface of each of the first slots of the deformed bar, having a Vickers hardness value greater than or equal to 500HV0.05 as determined in accordance with ASTM E384-11e1, Includes, The first slot surface and the second slot surface of adjacent pairs of irregularly shaped bars define a plurality of slots in the screen cylinder. The contact between the solid suspension and the screen cylinder causes at least a portion of the solid suspension to pass through the slot; and A step of recovering an acceptable solid suspension from the plurality of slots of the screen cylinder, Methods that include...

[0164] Embodiment 21 The method according to Embodiment 20, further comprising removing at least a portion of solid foreign matter from the outer surfaces of the plurality of irregularly shaped bars.

[0165] Embodiment 22 The method according to any one of Embodiments 20 or 21, wherein each of the plurality of irregularly shaped bars includes a chromium layer deposited on the outer surface of the irregularly shaped bar or on the hardened layer.

[0166] Embodiment 23 The method according to any one of embodiments 20 to 22, wherein the hardened layer is a hard coating applied to at least a portion of the surface of the first slot of the irregularly shaped bar.

[0167] Embodiment 24 The method according to any one of Embodiments 20 to 22, wherein the hardened layer includes a surface treatment layer for the base material of the irregularly shaped bar.

Claims

1. In a screen cylinder, Multiple irregularly shaped bars, which are aligned in the longitudinal direction and connected to at least one support ring at the mounting end of the multiple irregularly shaped bars, Includes, Each of the aforementioned multiple irregularly shaped bars is Outer surface facing outward from at least one of the support rings; A first slot surface extending from the outer surface of the irregularly shaped bar to the mounting end on the opposite side of the outer surface; A second slot surface, on the opposite side of the first slot surface, extending from the outer surface of the irregular bar to the mounting end, wherein the first slot surface of one irregular bar and the second slot surface of another immediately adjacent irregular bar define a slot; and A hardened layer provided on at least a portion of the first slot surface and the second slot surface of the irregularly shaped bar, having a Vickers hardness value greater than or equal to 1000HV0.05 as determined in accordance with ASTM E384-11e1, Includes, The slot width of the aforementioned slot varies along the longitudinal length of the irregularly shaped bar within a tolerance of less than or equal to 15 μm. A screen cylinder in which the slot width is the shortest distance between the first slot surface of one irregularly shaped bar and the second slot surface of another immediately adjacent irregularly shaped bar.

2. The screen cylinder according to claim 1, wherein the hardened layer is installed on the outer surface of each of the irregularly shaped bars.

3. The hardened layer is applied to the entire outer edge surface of each of the irregularly shaped bars. The screen cylinder according to claim 1 or 2, wherein the entire outer edge surface includes at least the outer surface, the first slot surface, and the second slot surface.

4. The screen cylinder according to any one of claims 1 to 3, wherein the hardened layer has an outer surface of the hardened layer having a topography in which the dimensions are constant to a tolerance smaller than or equal to 9 μm.

5. The screen cylinder according to any one of claims 1 to 4, wherein the hardened layer has a Vickers hardness value greater than or equal to 1100HV0.05 when determined in accordance with ASTM E384-11e1.

6. The screen cylinder according to any one of claims 1 to 5, wherein the base material of each of the plurality of irregularly shaped bars is stainless steel.

7. The screen cylinder according to any one of claims 1 to 6, wherein the base material of each of the plurality of irregularly shaped bars is not annealed.

8. The screen cylinder according to any one of claims 1 to 7, further comprising a chromium layer installed on the outer surface of the irregularly shaped bar or on the hardened layer.

9. The screen cylinder according to claim 8, wherein the thickness of the chrome layer on each of the irregularly shaped bars decreases from the outer surface of each of the irregularly shaped bars toward the mounting end.

10. The screen cylinder according to any one of claims 1 to 9, wherein the outer surface of each of the plurality of irregularly shaped bars includes the hardened layer, and a chromium layer is installed on the hardened layer.

11. The screen cylinder according to any one of claims 1 to 10, wherein the hardened layer is a hard coating applied to at least a portion of the surface of the first slot of the irregularly shaped bar.

12. The screen cylinder according to claim 11, wherein the thickness of the hard coating is greater than or equal to 5 μm, or between 5 μm and 300 μm.

13. The screen cylinder according to any one of claims 11 or 12, wherein the hard coating includes tungsten carbide, chromium carbide, titanium nitride, chromium nitride, electroless nickel plating, ceramic coating, alumina, composite film, or a combination thereof.

14. The screen cylinder according to any one of claims 11 to 13, wherein the hard coating includes a ceramic coating.

15. The screen cylinder according to any one of claims 1 to 14, wherein the hardened layer has an electrical conductivity that is within 10% of the electrical conductivity of the base material of the plurality of irregularly shaped bars.

16. The second slot surface includes a nose that protrudes from the second slot surface toward the first slot surface of the other adjacent irregularly shaped bar, The screen cylinder according to any one of claims 1 to 15, wherein the hardened layer is formed on the nose of the second slot surface and on a portion of the first slot surface opposite to the nose.

17. A screen cylinder according to any one of claims 1 to 16, which functions to separate solid foreign matter from a solid suspension.

18. The screen cylinder according to any one of claims 1 to 17, wherein the slot width is 0.08 to 1.5 mm.

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