Screen drum

Abstract

The screen drum includes forming bars longitudinally aligned and coupled to at least one support ring. Each of the profiled bars includes an outer surface facing away from the support ring, a first slot surface extending from the outer surface to the attachment end, and a second slot surface opposite the first slot surface and extending from the outer surface to the attachment end of the profiled bar. The first slot surface of one forming bar and the second slot surface of another immediately adjacent forming bar define a slot. The forming rod includes a hardened layer integral with or disposed on at least a portion of the first groove surface of the forming rod. The Vickers hardness of the hardened layer may be greater than the hardness of the base metal.

Description

This invention patent application is a divisional application of the invention patent application with international application number PCT / US2020 / 029461, international application date April 23, 2020, application number 202080047122.X entering the Chinese national phase, and name “Screen cylinder with improved slot width protection and method for removing solid contaminants from solid suspension”. CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority under 35 U, SC. ​​§120 to U.S. Provisional Application No. 62 / 839,314, filed on April 26, 2019, entitled “Screen Cylinder with Improved Slot Width Protection,” the entire contents of which are hereby incorporated by reference into this disclosure. Background Art Technical Field

[0002] The present specification relates generally to screen cylinders for removing oversized solid contaminants from a solid suspension, and in particular to screen cylinders having improved slot width protection and methods of making and using screen cylinders having improved slot width protection. Technical Background

[0003] In the papermaking industry, the process of making paper requires the production of pulp, which is a solid suspension of fibers, such as cellulose fibers or other fibers. Depending on the source of the fibers, the pulp can include solid contaminants of various concentrations and sizes, such as wood chips, fiber bundles, metal flakes, hardened adhesives or other contaminants. For example, the increasing use of recycled paper as a source of fiber may increase the presence of hardened adhesives, metal chips and wood chips in the pulp. These excessively large solid contaminants may reduce the quality of the paper and / or cause flow interruptions in the pulp in the headbox of a Fourdrinier paper machine or other papermaking processes.

[0004] Before the pulp is introduced into the papermaking process, the pulp is usually screened to remove these oversized solid contaminants from the pulp. Screening pulp can also be used to classify pulp according to fiber length or fiber hardness. Pulp screening can be accomplished by introducing the pulp into a pressure screen, wherein the acceptable portion of the pulp passes through the holes or slots in the screen. The solid contaminants or unacceptable portion of the pulp (e.g., long fibers or rigid fibers if screening is performed based on the characteristics of the fibers) do not pass through the slots or holes in the screen and are discharged from the waste outlet. The pressure screen can also be used to remove oversized solid contaminants from mud and solid suspensions in other industries outside the pulp and papermaking industry. Summary of the invention

[0005] Therefore, there is a continuous need for a pressure screen with improved wear properties. In particular, there is a need for a screen cylinder having a hardened layer in the groove area to reduce the wear of the groove area.

[0006] According to one or more aspects of the present disclosure, the screen drum may include a plurality of forming rods, which are longitudinally aligned and connected to at least one support ring at the attachment ends of the plurality of forming rods. Each of the plurality of forming rods may include an outer surface facing away from at least one support ring, a first groove surface extending from the outer surface to the attachment end of the forming rod opposite to the outer surface, and a second groove surface opposite to the first groove surface and extending from the outer surface to the attachment end of the forming rod. The first groove surface of a forming rod and the second groove surface of another adjacent forming rod may define a groove. The forming rod may also include a hardened layer, which is integrated with at least a portion of the first groove surface of the forming rod, and the Vickers hardness value of the hardened layer is greater than or equal to 500HV0.05 as determined according to ASTM E384-11e1.

[0007] According to another aspect of the present disclosure, a shaped rod of a screen cylinder for separating solid contaminants from a solid suspension may include an attachment end and an outer surface disposed at an end opposite to the attachment end. The shaped rod may also include a first groove surface extending from the outer surface to the attachment end of the shaped rod and a second groove surface opposite to the first groove surface and extending from the outer surface to the attachment end. The shaped rod may also include a hardened layer, the hardened layer being integrated with at least a portion of the first groove surface, a portion of the second groove surface, or both, and the Vickers hardness value of the hardened layer is greater than or equal to 500 HV0.05 as determined according to ASTM E384-11e1.

[0008] According to another aspect of the present disclosure, a method for making a hardened forming rod for a screen drum may include providing a forming rod, the forming rod including an attachment end and an outer surface facing the direction opposite to the attachment end. The forming rod may also include a first groove surface extending from the outer surface to the attachment end of the forming rod and a second groove surface opposite to the first groove surface and extending from the outer surface to the attachment end. The method may also include forming a hardened layer on at least a portion of the first groove surface or integrally therewith. Determined according to ASTM E384-11e1, the Vickers hardness value of the hardened layer may be greater than or equal to 500HV0.05. The method may also include depositing a chromium layer on the outer surface of the forming rod or on the hardened layer.

[0009] According to other embodiments of the present disclosure, a method for removing solid contaminants from a solid suspension may include contacting the solid suspension with a screen drum. The screen drum may include a plurality of profiled rods coupled to at least one support ring and aligned longitudinally. Each of the plurality of profiled rods may include an outer surface facing away from at least one support ring, a first groove surface extending from the outer surface to an attachment end of the profiled rod opposite to the outer surface, and a second groove surface opposite to the first groove surface and extending from the outer surface to the attachment end of the profiled rod. Each of the profiled rods may also include a hardened layer integral with or disposed on at least a portion of the first groove surface of each of the profiled rods. The Vickers hardness value of the hardened layer may be greater than or equal to 500HV0.05 as determined according to ASTM E384-11e1. The first groove surface and the second groove surface of the profiled rods paired side by side may define a plurality of grooves of the screen drum, and contact of the solid suspension with the screen drum may cause at least a portion of the solid suspension to pass through these grooves. The method may also include collecting acceptable solid suspensions from a plurality of grooves of the screen drum.

[0010] It is to be understood that both the foregoing summary and the following detailed description describe various embodiments and are intended to provide an overview or framework for understanding the nature and character of the claimed subject matter. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The accompanying drawings are included to provide a further understanding of the various embodiments and are incorporated in and constitute a part of this specification. The accompanying drawings illustrate various embodiments described herein and together with the description serve to explain the principles and operations of the claimed subject matter.

[0012] Figure 1 schematically depicts a front perspective view of a screen cartridge according to one or more embodiments shown and described herein;

[0013] Figure 2A Schematically depicts a schematic diagram of a system according to one or more embodiments shown and described herein. Figure 1 A perspective view of a portion of a screen cylinder showing a plurality of profiled rods coupled to a support ring of the screen cylinder;

[0014] Figure 2B Schematically depicts a schematic diagram of a system according to one or more embodiments shown and described herein. Figure 1 Another perspective view of a portion of a screen cylinder showing a plurality of profiled rods coupled to a support ring of the screen cylinder;

[0015] Figure 3 Schematically depicts a schematic diagram of a system according to one or more embodiments shown and described herein. Figure 1 A cross-sectional view of three profiled bars of a screen cylinder, the profiled bars having a chrome layer on the outer surface of the profiled bars;

[0016] Figure 4 Schematically depicts a schematic diagram of a system according to one or more embodiments shown and described herein. Figure 3 a cross-sectional view of a portion of a profiled rod after a certain period of use, wherein a portion of a first groove surface of the profiled rod has worn away, resulting in a larger groove;

[0017] Figure 5 schematically depicts a cross-sectional view of a formed rod having a hardened layer and a chrome layer deposited on the hardened layer according to one or more embodiments shown and described herein;

[0018] Fig. 6A schematically depicts a cross-sectional view of a profiled rod having a hardened layer on a portion of a first groove surface of the profiled rod and a chrome layer on top of the hardened layer according to one or more embodiments shown and described herein;

[0019] Figure 6B schematically depicts a cross-sectional view of a profiled rod having a hardened layer on a first groove surface and an outer surface of the profiled rod and a chrome layer formed on the hardened layer according to one or more embodiments shown and described herein;

[0020] Figure 6C schematically depicts a cross-sectional view of a formed rod having a hardened layer on a first groove surface and a second groove surface of the formed rod according to one or more embodiments shown and described herein;

[0021] Fig.6D schematically depicts a cross-sectional view of a profiled rod having a hardened layer on the entire outer peripheral surface of the profiled rod and a chrome coating applied to the hardened layer according to one or more embodiments shown and described herein;

[0022] Figure 7 schematically depicts a cross-sectional view of a portion of a formed rod in which a hardened layer is formed integrally with a base metal of the formed rod according to one or more embodiments shown and described herein;

[0023] Figure 8 Schematically depicts a schematic diagram of a system according to one or more embodiments shown and described herein. Figure 7 A cross-sectional view of a portion of a hardened layer of a formed rod; and;

[0024] Fig. 9 Schematically depicted is a cross-sectional view of a portion of a formed rod, wherein the hardening layer comprises a coating applied to at least a first groove surface, a second groove surface, and an outer surface of the formed rod, according to one or more embodiments shown and described herein. DETAILED DESCRIPTION

[0025] Reference will now be made in detail to embodiments of a screen cylinder having hardened, formed rods, examples of which are illustrated in the accompanying drawings. Whenever possible, the same reference numerals will be used throughout the drawings to refer to the same or like parts. Figure 1 2, a screen drum 10 according to an embodiment of the present disclosure is shown. The screen drum 10 may include a plurality of forming rods 12, the plurality of forming rods 12 being longitudinally aligned and coupled to at least one support ring 14 at the attachment ends 30 of the plurality of forming rods 12. Referring to FIG. 2, each of the forming rods 12 may include an outer surface 32 facing away from the support ring 14, a first groove surface extending from the outer surface 32 to the attachment end 30 of the forming rod 12, and a second groove surface opposite the first groove surface and extending from the outer surface 32 to the attachment end 30 of the forming rod 12. The first groove surface of one forming rod and the second groove surface of another adjacent forming rod may define a groove 20. Each of the forming rods may include a hardened layer integral with or disposed on at least a portion of the first groove surface of the forming rod 12, the hardened layer having a Vickers hardness value greater than the base metal of the forming rod 12. In some embodiments, the forming rod may further include a chromium layer disposed on the outer surface of the forming rod 12 or on the hardened layer. During operation of the screen drum 10, a portion of the acceptable solid suspension flows through the grooves 20 in the grooved cylindrical wall 16. The hardened layer applied to the profiled rod 12 can reduce wear of the groove surfaces of the profiled rod 12 by the abrasive solid components of the solid suspension. Reducing wear can reduce widening of the grooves 20, which can maintain the separation efficiency of the screen drum 10 over time. Reducing wear at the groove surfaces over time while maintaining the separation efficiency of the screen drum 10 can increase the useful life of the screen drum.

[0026] Unless otherwise stated, it is not intended that any method described herein be construed as requiring that its steps be performed in a particular order, or requiring any apparatus, or a particular orientation. Therefore, in the event that a method claim does not specifically recite the order to be followed by the steps of the method, or in the event that any apparatus claim does not specifically recite the order or orientation of individual components, or in the event that the steps are not specifically stated in the claims or specification to be limited to a particular order, or in the event that a particular order or orientation of components of the apparatus is not recited, no order or orientation can be inferred in any way in any respect. This applies to any possible non-explicit basis for interpretation, including: logical matters regarding arrangement of steps, operational flow, order of components, or orientation of components; obvious meaning derived from grammatical organization or numbering, and; the number or type of embodiments described in the specification.

[0027] Directional terms used herein—eg, up, down, right, left, front, back, top, bottom—are made with reference only to the drawings drawn and the coordinate axes provided and are not meant to imply an absolute orientation.

[0028] As used herein, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to "a" component includes aspects having two or more such components unless the context clearly dictates otherwise.

[0029] As used herein, the term "longitudinal" may refer to an orientation or direction that is generally parallel to the central axis A of the screen drum.

[0030] As used herein, the term "radial" may refer to the direction from the screen drum ( Figure 1 ) in the direction of any radius extending outward from the central axis A.

[0031] As used herein, the terms "upstream" and "downstream" may refer to the relative position of features with respect to the direction of flow of a solid suspension or slurry. For the screen cylinder of the present disclosure, the flow of the solid suspension is generally from the outer surface 32 of the forming rod 12 toward the attachment end 30 of the forming rod 12.

[0032] As used herein, the term "solid contaminants" or "oversized solid contaminants" may refer to solid objects, such as wood chips, metal pieces, dried adhesive, or other contaminants, which are not intended and are not desired to be in a solid suspension or slurry, and can be distinguished from solid components, such as fibers, etc., that are intended to be in a solid suspension.

[0033] Unless otherwise specified, the Vickers hardness values ​​provided herein for the base metal, hardened layer 50, and chrome layer 40 refer to Vickers hardness values ​​determined in accordance with ASTM E384-11e1, with an indenter load of 0.05 kilograms of force (kgf).

[0034] In the pulp and paper industry, pulp screening can be accomplished by a pressure screening process using a screen cylinder. The pressure screening process can include introducing a solid suspension, such as a solid suspension of fibers, into a screen cylinder. The fibers can be any type of fiber, such as, but not limited to, cellulose fibers, cotton fibers, glass fibers, or other fibers. The screen cylinder can be an inflow screen cylinder, in which the acceptable portion of the solid suspension flows radially inward through the screen cylinder, or an outflow screen cylinder, in which the acceptable portion of the solid suspension flows radially outward through the screen cylinder. The screen cylinder may include a rotor or other device operable to remove solid contaminants from the screen cylinder. Some screen cylinders used for pressure screening of pulp or other solid suspensions and slurries may have an integral screen cylinder, including a solid metal cylinder, through which a plurality of holes or slots are drilled or milled. However, these integral screen cylinders are limited in throughput through the screen portion due to the limited slot area through which the acceptable portion of the solid suspension can pass. The pulp and paper market has an increasing demand for pulp screening process efficiency with respect to greater throughput and greater ability to separate oversized solid contaminants from the solid suspension.

[0035] In order to increase the throughput of the pressure screening process, a screen cylinder was developed that includes a plurality of longitudinally arranged profiled bars defining a plurality of slots extending the length of the screen cylinder. Figure 1 , 2A 2B schematically depicts a screen cylinder 10 of the present disclosure including a plurality of forming rods 12. The screen cylinder 10 includes a plurality of forming rods 12 that are longitudinally aligned and coupled to at least one support ring 14 at the attachment ends 30 of the plurality of forming rods 12. In some embodiments, the at least one support ring 14 may include a plurality of support rings 14. The screen cylinder 10 may also include an annular end flange 19 at either axial end of the screen cylinder 10.

[0036] Each of the forming rods 12 can be longitudinally aligned with the central axis A of the screen drum 10 and with each of the other forming rods 12. The forming rods 12 can be arranged side by side along the circular inner or outer periphery of the support ring 14 to form a grooved cylindrical wall 16. The grooved cylindrical wall 16 formed by a plurality of forming rods 12 can include grooves 20 defined between each pair of adjacent pairs of forming rods 12. The grooves 20 can extend the length of the screen drum 10 between the two annular end flanges 19. Further features and aspects of the support structure and operation of the screen drum 10 of the present disclosure can be found in U.S. Patent No. 8,469,198, the entire contents of which are incorporated herein by reference.

[0037] By having the slots 20 extend the length of the screen cylinder 10, the screen cylinder 10 including the plurality of profiled bars 12 generally provides an increased open area through which an acceptable solid suspension can flow. The greater open area provided by the slots 20 of the screen cylinder 10 can provide a greater throughput through the screen cylinder 10 as compared to a monolithic screen cylinder having holes or slots drilled or milled into a metal cylinder. Figure 1 , 2A 2B as an outward flow screen cylinder 10, wherein the acceptable solid suspension flows radially outward through the slots 20. However, it will be appreciated that the features of the present disclosure may be equally suitably applied to an inward flow screen cylinder or any other type of pressure screening device employing a plurality of profiled rods. The screen cylinder 10 may be operable to separate solid contaminants from the solid suspension.

[0038] refer to Figure 3 , depicting an embodiment of forming rods 12. Each of the forming rods 12 may have an attachment end 30 coupled to the support ring 14. Each of the forming rods 12 may have an outer surface 32 facing away from at least one support ring 14. The outer surfaces 32 of the plurality of forming rods 12 may form the grooved cylindrical wall 16 ( Figure 1 ). Still refer to Figure 3, each of the forming bars 12 may have a first groove surface 34 extending from the outer surface 32 to the attachment end 30 of the forming bar 12, the attachment end being opposite the outer surface 32. Each of the forming bars 12 may have a second groove surface 36, which is on a side opposite to the first groove surface 34 and extends from the outer surface 32 to the attachment end 30 of the forming bar 12. The first groove surface 34 of one forming bar 12 and the second groove surface 36 of another immediately adjacent forming bar 12 define one of the grooves 20 of the screen drum 10. When two forming bars 12 are referred to as being "immediately adjacent", the two forming bars 12 are side by side, so the first groove surface 34 of the first forming bar and the second groove surface 36 of the second forming bar define the groove 20, and no other forming bars are disposed between the first forming bar and the second forming bar.

[0039] The first groove surface 34 may have a first profile, and the second groove surface 36 may have a second profile. The second groove surface 36 may meet the outer surface 32 of the shaped bar 12 at a nose 38 that protrudes toward the first groove surface 34 of the adjacent shaped bar 12. At the nose 38, the second profile of the second groove surface 36 of one shaped bar 12 may converge with the first profile of the first groove surface 34 of another adjacent shaped bar 12. Therefore, the narrowest portion of the groove 20 may be defined between the nose 38 of the second groove surface 36 of the shaped bar 12 and the first groove surface 34 of the adjacent shaped bar. Downstream of the nose 38, the second profile of the second groove surface 36 of the shaped bar 12 and the first profile of the first groove surface 34 of the adjacent shaped bar 12 may diverge to widen the width of the groove 20 downstream of the nose 38. As previously described, the flow of the solid suspension through the groove 20 is generally from the outer surface 32 of the shaped bar 12 toward the attachment end 30. The first profile and the second profile may have different Figure 3 For example, in embodiments, the first groove surface 34, the second groove surface 36, or both may include a smooth or straight surface extending from the attachment end 30 to the outer surface 32 of the forming rod 12, or each may have a profile having a substantially constant curvature from the attachment end 30 to the outer surface 32 of the forming rod 12. It will be appreciated that the first groove surface 34 and the second groove surface 36 may have any suitable shape for creating a screen cylinder for removing oversized solid contaminants from slurries and solid suspensions.

[0040] refer to Figure 3 , each of the profiled rods 12 may include a chrome layer 40 applied to one or more surfaces. In particular, the profiled rods 12 may include a chrome layer 40 applied to the outer surface 32. The outer surface 32 of the profiled rods 12 may be subjected to pressure pulses from the rotor that provide sufficient cleaning action to remove the grooved cylindrical wall 16 ( Figure 1) to remove oversized solid contaminants. The chrome layer 40 on the outer surface 32 can increase the hardness of the outer surface 32 to reduce wear caused by these pressure pulses. The Vickers hardness value (HV) of the chrome layer 40 can be from 900 HV0.05 to 1000 HV0.05 if determined according to ASTM E384-11e1 using an indenter load of 0.05 kilograms force (kgf).

[0041] The chromium layer 40 may be applied to the outer surface 32 of the profiled rods 12 after the screen cylinder 10 is assembled. The chromium layer 40 may be applied using an electroplating process. When electroplating the screen cylinder 10, chromium generally preferentially deposits at the area with the lowest resistance to electrical current, which is generally the outer surface 32 of the parallel rods 12. Since chromium is deposited on the surface with the least resistance, the chromium layer 40 may be inconsistent and non-uniform across the circumferential surface of the profiled rods 12. Figure 3 , the chromium layer 40 may be thicker in areas of low resistance and thinner or absent in areas of high resistance. For these reasons, it may be difficult to deposit a chromium layer on the first groove surface 34 and / or the second groove surface 36 of the formed rod 12, which, due to geometric considerations, are more resistant to electrical current than the outer surface 32 of the formed rod 12. As a result, the chromium layer 40 on the first groove surface 34 and / or the second groove surface 36 may be very thin or even absent.

[0042] The screen cylinder 10 may be subjected to electroplating for a period of time sufficient to establish the chromium layer 40 on the first and second groove surfaces 34, 36. However, chrome plating is very expensive, and environmental regulation of chrome use and chrome processes is increasing. In addition, prolonged exposure to the electroplating process may simply result in a greater degree of non-uniformity in the chromium layer 40. Non-uniformity in the chromium layer 40 may result in variations in the slot width from one slot 20 to the next and along the longitudinal length of the slot 20. Even if the chromium layer 40 on each of the plurality of forming rods 12 is deposited prior to assembling the screen cylinder 10, the chromium layer 40 may still be non-uniform, resulting in a different thickness of the chromium layer 40 on all peripheral surfaces of the forming rods 12. Grinding the chromium layer 40 after electroplating to produce a more uniform chromium layer 40 may be labor intensive and may result in a waste of chromium that is plated onto the surfaces of the forming rods 12 at high cost.

[0043] Inconsistencies in the chromium layer 40 produced by electroplating may result in some portions of the first and second slot surfaces 34, 36 having a thin chromium layer 40 or no chromium layer 40 deposited thereon. The thin chromium layer 40 may provide some initial protection against wear, but the thin chromium layer 40 may wear away, exposing the underlying base metal. When no chromium layer 40 is formed on the slot surfaces, the base metal, which may have a Vickers hardness value of less than or equal to 400 HV0.05, may be directly exposed to the abrasive flow of the solid suspension through the slots 20. In either case (e.g., a thin chromium layer 40 or no chromium layer 40 on the first and / or second slot surfaces 34, 36), the first and / or second slot surfaces 34, 36 may experience excessive wear during operation of the screen drum 10, changing the width of the slots and reducing the separation efficiency of the screen drum 10.

[0044] refer to Figure 4 , schematically depicts a typical wear pattern of a profiled rod 12. Figure 4 In FIG. 1 , the dotted line represents the original profile of the first groove surface 34 before the screen drum 10 is introduced into use, while the solid line represents the profile of the first groove surface 34 after the screen drum 10 has been used for a period of time. Figure 4 As shown in FIG. 1 , the wear may be greatest at the portion where the first slot surface 34 directly passes through the slot 20 from the nose 38 of the immediately adjacent forming rod 12. As the first slot surface 34 wears in the nose 38 region close to the immediately adjacent forming rod 12, the slot width W increases over time. Increasing the slot width W can increase the throughput of the screen drum 10, but it may also reduce the efficiency of the screen drum 10 in separating oversized solid pollutants from the solid suspension. Therefore, wear may cause an increase in the concentration and / or average size of solid pollutants and debris in the acceptable solid suspension that enters the downstream of the screen drum 10 through the screen drum 10. As a result, when used to remove solid pollutants from a solid suspension of cellulose fibers or other solid components, the screen drum 10 having a thin or non-existent chrome layer 40 on the first slot surface 34 and / or the second slot surface 36 may have a reduced service life. In some cases, the service life may be reduced to only 3 to 12 months. Therefore, it is desirable to increase the hardness of first groove surface 34 , second groove surface 36 , or both in the area of ​​groove 20 to reduce wear and maintain the separation efficiency of screen drum 10 , which may increase the useful life of screen drum 10 .

[0045] As previously mentioned, the present disclosure is directed to a profiled bar 12 having a hardened layer that can reduce wear of at least the first groove surface 34 and the screen drum 10 including the profiled bar 12. Figure 5The profiled rod 12 of the screen drum 10 for separating solid pollutants from suspended solids of the present disclosure may include an attachment end 30, an outer surface 32 disposed at an end opposite to the attachment end 30, a first groove surface 34 extending from the outer surface 32 to the attachment end 30 of the profiled rod 12, and a second groove surface 36 opposite to the first groove surface 34 and extending from the outer surface 32 to the attachment end 30. The profiled rod 12 of the present disclosure further includes a hardened layer 50, which may be integrated with or disposed on at least a portion of the first groove surface 34, a portion of the second groove surface 36, or both, and the Vickers hardness value of the hardened layer 50 may be greater than the Vickers hardness of the base metal of the profiled rod 12. The Vickers hardness value of the hardened layer 50 may be greater than or equal to 500 HV0.05, greater than or equal to 700 HV0.05, greater than or equal to 900 HV0.05, greater than or equal to 1000 HV0.05, greater than or equal to 1100 HV0.05, or even greater than or equal to 1200 HV0.05. In some embodiments, the formed rod 12 may additionally include a chromium layer 40 disposed on the outer surface 32 (such as when the hardened layer 50 is integral with the base metal 46) or on the hardened layer 50 (such as when the hardened layer 50 is coated on the outer surface 34 of the base metal 46). Therefore, it should be understood that the chromium layer 40 is different from the hardened layer 50 and can be deposited on the hardened layer 50. In some embodiments, the formed rod 12 may include the hardened layer 50 without the chromium layer 40.

[0046] like Figure 5 As shown, when a plurality of forming rods 12 are arranged longitudinally and side by side, the first groove surface 34 of one forming rod 12 and the second groove surface 36 of another adjacent forming rod 12 define one of the grooves 20 of the screen drum 10. The groove 20 may have such a groove width W, that is, sufficient to allow a portion of the solid suspension to pass through the groove 20 while preventing excessive solid contaminants from passing through. The groove 20 may have a groove width W, which is the shortest distance between the first groove surface 34 of one forming rod 12 and the second groove surface 36 of the adjacent forming rod 12. For the screen drum 10 for screening pulp, the groove 20 may have a groove width W greater than or equal to 80 microns (0.08 mm), such as from 0.08 mm to 1.5 mm. The groove width W disclosed herein can generally be used for screening pulp. However, for applications in other industries, such as but not limited to mining and drilling, food processing, water treatment or other industries, it is understood that the space between the forming rods 12 and the groove width W may be larger or smaller depending on the specific industry application. The groove width W of the groove 20 can be uniform along the longitudinal length of the forming rod 12. In some embodiments, the groove width W of the groove 20 can vary within a tolerance range of less than or equal to 15 microns, less than or equal to 10 microns, less than or equal to 8 microns, less than or equal to 7 microns, or even less than or equal to 6 microns when the screen cylinder 10 is fully assembled.

[0047] Each of the formed rods 12 may include a base metal 46. The base metal 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 metal 46 may be stainless steel, such as 304 stainless steel or 316 stainless steel. The Vickers hardness value of the base metal 46 without the hardening layer 50 may be lower than the Vickers hardness value of the chromium layer 40, the hardening layer 50, or both. In some embodiments, the Vickers hardness of the base metal 46 may be less than 500 HV0.05, less than or equal to 450 HV0.05, even less than or equal to 425 HV0.05, or even less than or equal to 400 HV0.05. In some embodiments, the base metal 46 may be non-annealed.

[0048] Reference again Figure 5 The hardened layer 50 may be integral with or disposed on the base metal 46 of the formed rod 12. The hardened layer 50 may be disposed at any portion of the first groove surface 34, the second groove surface 36, the outer surface 32, or a combination thereof. Fig. 6A In some embodiments, the hardening layer 50 may be integral with or disposed on at least a portion of the first groove surface 34 of the forming rod 12. As previously described, the first groove surface 34 proximate the nose 38 of the forming rod 12 may be the area of ​​the outer peripheral surface of the forming rod 12 that experiences the greatest wear from the flow of the solid suspension through the groove 20. The hardening layer 50 may also be integral with or disposed on some portion of the outer surface 32 of each of the forming rods 12, the second groove surface 36, or both.

[0049] refer to Figure 6B In some embodiments, the hardened layer 50 may be integral with or disposed on the first groove surface 34 and the outer surface 32 of the formed rod 12. When present, the chrome layer 40 may be deposited on top of the hardened layer 50 at the outer surface 32 of the formed rod 12. Figure 6C In some embodiments, the hardened layer 50 may be integral with the first groove surface 34 and the second groove surface 36. The hardened layer 50 on the second groove surface 36 may extend over the nose 38 of the profiled rod 12. When present, the chrome layer 40 may be formed on the outer surface 32 of the profiled rod 12 and on portions of the hardened layer 50 proximate the outer surface 32. Fig.6DIn some embodiments, the hardening layer 50 may be integral with or disposed on the entire peripheral surface of each of the forming rods 12, including at least the outer surface 32, the first groove surface 34, and the second groove surface 36. As used herein, the term "entire peripheral surface" may mean that the hardening layer 50 is integral with or disposed on at least 80%, at least 85%, at least 90%, at least 95%, or at least 99% of the peripheral surface of the forming rod 12. In some embodiments, the hardening layer 50 may be integral with or disposed 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 peripheral surface of the forming rod 12.

[0050] The hardening layer 50 may have a thickness sufficient to protect the first groove surface 34 and / or the second groove surface 36 from the abrasive components of the solid suspension passing through the groove 20 to reduce or prevent wear of the forming rod 12 at the first groove surface 34 and / or the second groove surface 36. For example and without limitation, the thickness of the hardening layer 50 may be greater than or equal to 5 microns, greater than or equal to 10 microns, greater than or equal to 15 microns, or even greater than or equal to 20 microns. In some implementations, the thickness of the hardening layer 50 may be from 5 microns to 300 microns, from 5 microns to 250 microns, from 5 microns to 200 microns, from 5 microns to 100 microns, from 5 microns to 50 microns, from 5 microns to 30 microns, from 10 microns to 300 microns, from 10 microns to 100 microns, or from 10 microns to 50 microns. In some embodiments, the thickness of the hardening layer 50 may be greater than 300 microns without departing from the scope of the present disclosure.

[0051] The hardened layer 50 may have a hardness sufficient to reduce wear of the first groove surface 34 and / or the second groove surface 36 during operation of the screen drum 10. The hardness of the hardened layer 50 may be greater than the hardness of the base metal 46 of the profiled rod 12. For example, the Vickers hardness value of the hardened layer 50 may be greater than the Vickers hardness value of cold rolled stainless steel, which is approximately 400 HV0.05. In some implementations, the Vickers hardness value of the hardened layer 50 may be greater than or equal to 500 HV0.05, greater than or equal to 700 HV0.05, greater than or equal to 900 HV0.05, greater than or equal to 1000 HV0.05, greater than or equal to 1100 HV0.05, or even greater than or equal to 1200 HV0.05. The Vickers hardness value of the hardened layer 50 may be from 500 HV0.05 to 5000 HV0.05, from 700 HV0.05 to 2000 HV0.05, or even from 1000 HV0.05 to 1500 HV0.05. The Vickers hardness value may be determined by measuring with reference to the standard test method ASTM E384-11e1.

[0052] Reference again Figure 5, the hardened layer 50 may have a uniformly sized and smooth hardened layer outer surface 56. A hardened layer 50 having a uniformly sized and smooth hardened layer outer surface 56 is provided for a more uniform slot width W along the length of the screen drum 10, and for a more uniform slot width W from one slot 20 to the next. A hardened layer 50 having a hardened layer outer surface 56 with a smoother surface finish may also reduce resistance to the flow of an acceptable portion of the solid suspension through the slots 20, and promote a greater flow rate of the acceptable portion of the solid suspension through the screen drum 10. In other words, the smoother surface treatment of the hardened layer outer surface 56 may allow an acceptable portion of solids (e.g., fibers) in the solid suspension to flow through the slots 20 more easily than a base metal or chromium layer 40, thereby increasing the throughput of the screen drum 10 while maintaining effective separation of oversized solid contaminants from the solid suspension.

[0053] The dimensional consistency and smoothness of the hardened layer outer surface 56 may depend on the variation in thickness of the hardened layer 50. In some embodiments, the standard deviation of the thickness of the hardened layer 50 may be less than or equal to 5 microns, less than or equal to 2 microns, less than or equal to 1 micron, or even less than or equal to 0.5 microns. The smoothness of the surface finishing of the hardened layer outer surface 56 may be quantified by the surface roughness Ra value of the hardened layer outer surface 56. In some embodiments, the surface roughness Ra of the hardened layer outer surface 56 may be less than the surface roughness Ra of the base metal 46 before the hardened layer 50 is formed. In some embodiments, the surface roughness Ra of the hardened layer outer surface 56 may be smaller than the surface roughness Ra of the base metal 46, and the small amplitude is greater than or equal to 0.025 microns, greater than or equal to 0.030 microns, greater than or equal to 0.050 microns, or even greater than or equal to 0.100 microns. In some embodiments, the surface roughness Ra of the hardened layer outer surface 56 may be from 0.08 to 0.30 microns, from 0.09 to 0.25 microns, or from 0.09 to 0.20 microns. Prior to application of the hardening layer 50, the surface roughness Ra of the hardening layer outer surface 56 and / or the base metal 46 may be determined according to standard test methods known in the art, such as ASTM A 480 / 480M. As previously described, a reduced surface roughness of the hardening layer outer surface 56 may provide a smoother surface finish to the forming rods 12, which may facilitate an increase in the flow rate of an acceptable portion of the solid suspension through the screen drum 10.

[0054] In some embodiments where the chromium layer 40 may be applied, the conductivity of the hardened layer 50 may be similar to or slightly lower than the conductivity of the base metal 46 and other metal components of the screen cylinder 10 to reduce the difference in resistance during the electroplating process used to form the chromium layer 40 on the hardened layer 50. In some embodiments, the conductivity of the hardened layer 50 may be the same as the conductivity of the base metal 46 of the plurality of formed rods 12. In some embodiments, the conductivity of the hardened layer 50 may be within 10% of the conductivity of the base metal 46. The same or similar conductivity may allow the chromium layer 40 to be electroplated onto the hardened layer 50. As previously described, during electroplating to produce the chromium layer 40, chromium is preferentially deposited at areas of least resistance (e.g., areas of greatest conductivity). Therefore, if the conductivity of the hardened layer 50 is significantly lower than the conductivity of the base metal 46 or other metal components of the screen cylinder 10, the chromium is preferentially deposited on the base metal 46 or other metal components having greater conductivity and less resistance, rather than on the hardened surface of the formed rod 12, such as the outer surface 32 of the formed rod 12. If the conductivity of the hardened layer 50 is significantly lower than that of the base metal 46 or other metal components of the screen cylinder 10, then the chromium layer 40 formed on the hardened layer 50 at the outer surface 32 of the formed rod 12 may be very thin or non-existent, with the chromium having been preferentially deposited on the metal with greater conductivity. If the conductivity of the hardened layer 50 is less than that of the base metal 46, but still within 10%, then the chromium layer 40 may be deposited on the hardened layer 50, but the chromizing process may require additional time and / or the thickness of the chromium layer 40 may be less than that of the base metal 46 without the hardened layer 50. In some embodiments where the chromium layer 40 is not added, the conductivity of the hardened layer 50 may differ from the conductivity of the base metal 46 by more than 10%.

[0055] refer to Figure 7 In some embodiments, the hardened layer 50 may be integral with the base metal 46. As used herein, the term "integrated with" means that the hardened layer 50 is part of the base metal 46 and is inseparable therefrom (as opposed to the hardened layer 50 being coated on the base metal 46). A hardened layer 50 that is integral with the base metal 46 at one or more surfaces may be distinguished from a hardened layer 50 that is a coating, which is a material separate from the base metal 46 and is applied to the surface of the base metal 46 and attached or bonded thereto. The hardened layer 50 may be integral with the base metal 46 by treating the surface of the base metal 46 so that a portion of the base metal 46 near the surface is changed to form the hardened layer 50. Thus, the hardened layer 50 may include a surface treatment layer of the base metal 46 of the forming rod 12. As shown in FIG. Figure 7 As shown in , in some embodiments, the formed rod 12 may include a hardened layer 50 and may not have a chrome layer applied to the hardened layer 50 or to the outer surface 32 of the formed rod 12 .

[0056] Treating the surface of the base metal 46 to form the hardened layer 50 may include diffusing one or more chemical components into the base metal 46, wherein the diffusion of the chemical components into the surface of the base metal 46 may change the structure and / or properties of the base metal 46 near the outer surface to form the hardened layer 50. Examples of surface treatments that diffuse chemical components into the surface of the base metal 46 may include, but are not limited to, nitriding, nitrocarburizing, boriding (i.e., diffusing boron into the surface of the base metal 46), or other diffusion-based surface treatments. In the nitriding process, nitrogen from one or more nitrogen-containing compounds may diffuse into the surface of the base metal 46 at elevated temperature and pressure. The nitriding process may include a gas nitriding process, wherein the base metal 46 may be exposed to a gas composition containing a gaseous nitrogen-containing compound, such as, but not limited to, nitrogen (N2), ammonia (NH3), nitrogen plasma, or other nitrogen-containing gases. Alternatively, nitriding may also be performed using a liquid bath containing one or more molten nitrogen-containing salts, such as, but not limited to, alkaline cyanates.

[0057] During the nitrocarburizing process, both nitrogen and carbon, such as from carbon dioxide, carbonates, or other carbon-containing compounds, may diffuse into the surface of the base metal 46. The nitrocarburizing process may also be a gas phase or liquid phase process. For the boriding process, boron or a boron-containing compound may diffuse into the surface of the base metal 46. In some embodiments, the hardening layer 50 integral with the base metal 46 may include nitride ions. In some embodiments, the hardening layer 50 integral with the base metal 46 may include nitrogen, carbon, boron, or a combination of these diffused into the surface of the base metal 46.

[0058] Surface treatment of the base metal 46 to diffuse nitrogen, carbon, boron, or a combination thereof into the surface of the base metal 46 may change the structure of the base metal 46 near the surface. This structural change may increase the hardness of the base metal 46 near the surface, thereby achieving the formation of a hardened layer 50 that is integrated with the base metal 46. When the hardened layer 50 is integrated with the base metal 46, the outer surface 56 of the hardened layer may be consistent with the outer peripheral surface of the base metal 46 (e.g., the outer surface 32 of the forming rod 12, the first groove surface 34, and / or the second groove surface 36).

[0059] The hardened layer 50 that is integral with the base metal 46 may have a depth D in the base metal 46 sufficient to increase the hardness of the base metal 46. In some embodiments, the depth D of the hardened layer may be sufficient to allow some material to be removed from the hardened layer outer surface 56 by electropolishing while maintaining sufficient increased hardness to reduce wear of the hardened layer outer surface 56. Electropolishing may be performed after the surface treatment to prepare the hardened layer outer surface 56 for the chrome plating process to produce the chrome layer 40 when present. The depth D of the hardened layer 50 that is integral with the base metal 46 within the base metal 46 may be greater than or equal to 5 microns, greater than or equal to 10 microns, greater than or equal to 15 microns, or even greater than or equal to 20 microns. Examples of surface treatment processes for forming the hardened layer 50 integral with the base metal 46 may include, but are not limited to, hardening processes performed by BodyCote of the United Kingdom, Nitrex Metal Inc. of Quebec, Canada, Expanite A / S of Cleveland, Ohio, Burlington Engineering of Orange County, California, and other hardening processes.

[0060] In some embodiments, the hardened layer 50 integral with the base metal 46 may be formed by a nitriding process in which nitrogen diffuses into the surface of the base metal 46. In some embodiments, the hardened layer 50 integral with the base metal 46 may be formed by exposing the base metal 46 to a nitrogen-containing environment in which the temperature and pressure are sufficient to diffuse the nitrogen into the surface of the base metal 46. As previously described, the nitrogen-containing environment may be in a gas phase (e.g., a gas including ammonia) or a liquid phase (e.g., a molten salt bath including an alkali cyanate). During the nitriding process, the forming rod 12 may be maintained in an ammonia environment (e.g., ammonia vapor or an ammonia bath) at a temperature from about 175°C to about 700°C, such as from 175°C to 250°C, from 200°C to 600°C, from 200°C to 550°C, or from 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 metal 46. Annealing the base metal 46 may reduce the strength of the base metal 46, which may cause deformation of the formed rod 12 during assembly or use. In addition, during the nitriding process, excessively high temperatures may cause the formed rod 12 to deform, requiring further processing of the formed rod 12, or discarding the formed rod 12 due to material failure. In some embodiments, the base metal 46 of each of the formed rods 12 may not be annealed after the nitriding treatment. The formed rod 12 may be maintained at the nitriding temperature for a period of time from 5 minutes to 50 hours, such as from 1 hour to 50 hours, or from 1 hour to 20 hours in an ammonia environment. The nitriding process may be performed at ambient pressure or at a pressure greater than ambient pressure.

[0061] refer to Figure 8, the nitriding process may result in the formation of a compound layer 52 at the surface 47 of the base metal 46. The compound layer 52 is characterized by a structural change of the base metal 46 into an ε phase (ε-phase), a γ phase (γ-phase), or a combination of these. The compound layer 52 may provide hardness to the base metal 46, thereby forming a hardened layer 50 that is integral with the base metal 46. The compound layer 52 may extend to a depth D within the surface of the base metal 46. The depth D of the compound layer 52 may be greater than or equal to 5 microns, greater than or equal to 10 microns, greater than or equal to 15 microns, or even greater than or equal to 20 microns. For example, the depth D of the compound layer 52 after nitriding may be from 5 microns to 30 microns, from 10 microns to 30 microns, or from 15 microns to 25 microns. As Figure 8 As shown in , the nitride ions may further diffuse into the base metal 46 to form a diffusion zone 54 extending from the compound layer 52 further into the base metal 46 to a diffusion depth DT. The diffusion zone 54 may extend to a diffusion depth DT of at most 0.1 mm, or even at most 0.5 mm. The thickness of the compound layer 52 and the diffusion zone 54 may be determined according to ASTM B487-85 (2007).

[0062] One or more surfaces of the base metal 46, such as the outer surface 32, the first groove surface 34, the second groove surface 36, or a combination of these surfaces, may be subjected to nitriding, nitrocarburizing, boriding, or other surface treatment processes to produce a hardened layer 50 that is integral with the base metal 46. In some embodiments, the entire formed rod 12 may be subjected to nitriding, nitrocarburizing, boriding, or other surface treatment processes, whereby the entire peripheral surface, including the outer surface 32, the first groove surface 34, and the second groove surface 36, includes a hardened layer 50 that is integral with the base metal 46. Thus, the diffusion-based surface treatment may produce a hardened layer 50 that extends over the entire peripheral surface of the formed rod 12.

[0063] The Vickers hardness value of the hardened layer 50 integrated with the base metal 46 formed by nitriding, nitrocarburizing, nitrocarburizing, boriding or other surface treatment may be greater than that of the base metal 46. In some embodiments, the Vickers hardness value of the hardened layer 50 integrated with the base metal 46 may be greater than the Vickers hardness value of the chromium layer 40. The Vickers hardness of the hardened layer 50 integrated with the base metal 46 may be greater than or equal to 900 HV0.05, greater than or equal to 1000 HV0.05, greater than or equal to 1100 HV0.05, or even greater than or equal to 1200 HV0.05. In some embodiments, the Vickers hardness value of the hardened layer 50 integrated with the base metal 46 and formed by nitriding, nitrocarburizing, boriding or other surface treatment may be greater than or equal to 1400 HV0.05.

[0064] Treating the surface of the formed rod 12 by nitriding, nitrocarburizing, boriding or other processes can also produce a hardened layer 50 having a surface roughness Ra less than the surface roughness Ra of the base metal 46, and then treating the base metal 46 to form the hardened layer. In some embodiments, the surface roughness Ra of the hardened layer 50 that is integral with the base metal 46 can be at least 0.025 microns, at least 0.030 microns, at least 0.050 microns, or even at least 0.100 microns less than the surface roughness Ra of the base metal 46 before the surface treatment to form the hardened layer 50. As previously described, reducing the roughness of the first groove surface 34 and the second groove surface 36 can reduce the resistance to flow through the groove 20, which can increase the throughput of the screen drum 10 while maintaining separation efficiency.

[0065] Since the hardened layer 50 integrated with the base metal 46 is produced by changing the base metal 46, the conductivity of the hardened layer 50 integrated with the base metal 46 formed by nitriding, nitrocarburizing, boriding or other surface treatment processes can be within 10% of the conductivity of the base metal 46 before the treatment to form the hardened layer 50. Integrating the hardened layer 50 with the base metal 46 also does not result in a change in the geometry of the formed rod 12. Therefore, the formed rod 12 having the hardened layer 50 integrated with the surface of the formed rod 12 can be interchanged into a standard assembly without changing the support ring 14 or other structures used to secure the formed rod 12. In addition, the hardened layer 50 integrated with the base metal 46 can have a good bond with the chromium layer 40 and can exhibit reduced corrosion performance.

[0066] Reference now Fig. 9 In some embodiments, the hardening layer 50 may include a hard coating 60 applied to one or more surfaces of the base metal 46 of the forming rod 12. The hard coating 60 may be applied to the outer surface 32, the first groove surface 34, the second groove surface 36, or a combination of these surfaces. In some embodiments, the hardening layer 50 may be a hard coating 60 applied to the entire outer peripheral surface of the forming rod 12, including the outer surface 32, the first groove surface 34, and the second groove surface 36. In some embodiments, the hard coating 60 of the hardening 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 circumferential surface of the forming rod 12. In some embodiments, the hard coating 60 of the hardening layer 50 may be applied to at least the first groove surface 34 and the second groove surface 36.

[0067] The hard coating 60 of the hardening layer 50 can be applied to the base metal 46 by a known coating or spraying method, such as but not limited to high velocity oxygen fuel (HVOF) spraying, plasma spraying, laser spraying, chemical vapor deposition (CVD), physical vapor deposition (PVD), atomic layer deposition (ALD), electroplating, electroless plating (such as electroless nickel), ceramic coating, diamond-like carbon (DLC) coating, other coating methods, or combinations of these methods. In some embodiments, the hard coating 60 can be applied using an HVOF process. The hard coating 60 can include a compound having a hardness greater than that of the base metal 46. Examples of the hard coating 60 can include but are not limited to tungsten carbide, chromium carbide, titanium nitride, chromium nitride, electroless nickel, ceramic coating, aluminum oxide, other hard coating materials, or combinations of these. In some embodiments, the hard coating 60 can be a tungsten carbide coating. In some embodiments, the hardening layer 50 including the hard coating 60 can be a titanium nitride or chromium nitride coating applied by a PVD process. In some embodiments, the hard coating 60 of the hardening layer 50 may be a nickel layer 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 coating to one or more surfaces of the forming rod 12 and firing the forming rod at a temperature sufficient to cure the ceramic coating and bond the ceramic coating to the base metal 46.

[0068] The thickness of the hard coating 60 may be greater than or equal to 5 microns, greater than or equal to 10 microns, greater than or equal to 15 microns, or even greater than or equal to 20 microns. The thickness of the hard coating 60 may be less than or equal to 300 microns, less than or equal to 250 microns, less than or equal to 200 microns, less than or equal to 100 microns, or less than or equal to 50 microns. The thickness of the hard coating 60 may be from 5 microns to 300 microns, from 5 microns to 100 microns, or from 10 microns to 50 microns. The Vickers hardness value of the hard coating 60 may be sufficient to reduce or prevent wear of the first groove surface 34 and / or the second groove surface 36. The Vickers hardness value of the hard coating 60 may be greater than the Vickers hardness of the base metal 46. In some embodiments, the Vickers hardness value of the hard coating 60 may be greater than the chromium layer 40. The Vickers hardness of the hard coating 60 may be greater than or equal to 500 HV0.05, greater than or equal to 700 HV0.05, greater than or equal to 900 HV0.05, greater than or equal to 1000 HV0.05, or even greater than or equal to 1100 HV0.05.

[0069] Reference again Figure 5As previously described, in some embodiments, the forming rod 12 may include a chrome layer 40 disposed on the outer surface 32 of the forming rod 12 or on the hardened layer 50. The chrome layer 40 may protect the outer surface 32 of the forming rod 12 from wear and damage from pressure pulses from a rotor used to remove oversized solid contaminants from the grooved cylindrical wall 16 of the screen drum 10. In some embodiments, the outer surface 32 of each of the plurality of forming rods 12 may include the hardened layer 50, and the chrome layer 40 may be disposed on the hardened layer 50. The chrome layer 40 may also be formed on one or more portions of the first groove surface 34, the second groove surface 36, or both. On the first groove surface 34 and the second groove surface 36, the chrome layer 40 may be deposited on top of the hardened layer 50.

[0070] The average thickness of the chromium layer 40 can be sufficient to protect the outer surface 32 of the formed rod 12 and withstand the pressure pulses from the rotor. In some embodiments, the average thickness of the chromium layer 40 can be greater than or equal to 10 microns, greater than or equal to 20 microns, greater than or equal to 30 microns, or even greater than or equal to 40 microns. The chromium layer 40 can have a maximum thickness at the outer surface 32 of the formed rod 12. The thickness of the chromium layer 40 of each of the formed rods 12 can decrease from the outer surface 32 toward the attachment end 30 of each of the formed rods 12. The Vickers hardness value of the chromium layer 40 can be from about 900 HV0.05 to about 1000 HV0.05. In some embodiments, the formed rod 12 can have a hardened layer 50 without a chromium layer 40. In some embodiments, the formed rod 12 can be substantially free of chromium, such as having less than or equal to 5% chromium on the outer peripheral surface of the formed rod 12.

[0071] A method for manufacturing a hardened forming rod 12 for a screen drum 10 may include providing a forming rod 12 including an attachment end 30 and an outer surface 32 facing in a direction opposite to the attachment end 30. The forming rod 12 may include a first groove surface 34 extending from the outer surface 32 to the attachment end 30 of the forming rod 12 and a second groove surface 36 opposite the first groove surface 34 and extending from the outer surface 32 to the attachment end 30. The method may also include forming a hardened layer 50 on or integral with at least a portion of the first groove surface 34, the hardened layer 50 having a Vickers hardness value greater than the Vickers hardness of the base metal 46. The Vickers hardness value of the hardened layer 50 may be greater than or equal to 500 HV0.05, greater than or equal to 900 HV0.05, greater than or equal to 1000 HV0.05, greater than or equal to 1100 HV0.05, or even greater than or equal to 1200 HV0.05. The method may also include depositing chrome layer 40 on at least outer surface 32 of formed rod 12 or on hardened layer 50. In some embodiments, the method may include forming hardened layer 50 on a portion of outer surface 32, a portion of second groove surface 36, or both in addition to first groove surface 34.

[0072] In some embodiments, forming the hardened layer 50 may include subjecting at least the first groove surface 34 of the formed rod 12 to a surface treatment, wherein one or more chemical compounds diffuse into the base metal 46 at the first groove surface 34. In some embodiments, the method may include forming the hardened layer 50 on the entire peripheral surface of the formed rod 12 by subjecting the entire peripheral surface of the formed rod 12 to the surface treatment, the entire peripheral surface including the outer surface 32, the first groove surface 34, and the second groove surface 36. The method may include 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 peripheral surface of the formed rod 12. The surface treatment may include contacting at least a portion of the formed rod 12 with a nitrogen-containing gas at a temperature below the annealing temperature of the base metal 46 and at a pressure sufficient to diffuse nitrogen or a nitrogen-containing compound into the base metal 46. The nitrogen-containing gas may include nitrogen, ammonia, or other nitrogen gases. In some embodiments, the surface treatment for forming the hardening layer 50 integral with the base metal 46 may include a nitridation process. The nitridation process may be performed according to any of the operating parameters previously discussed herein.

[0073] In some embodiments, forming the hardened layer 50 may include applying a hard coating 60 to at least the first groove surface 34 of the forming rod 12. Applying the hard coating 60 may include any coating process discussed previously herein, and the hard coating 60 may be any material discussed previously herein. In some embodiments, applying the coating to at least the first groove surface 34 may include a thermal spray process. In some embodiments, the thermal spray process may include a tungsten carbide high velocity oxygen fuel (high velocity oxygen spray, HVOF) process.

[0074] The method of producing the formed rod 12 may include polishing the formed rod 12 to prepare the hardened layer 50 for electroplating the chrome layer 40 thereon. Polishing may include polishing processes for metal parts known in the art. The polishing step may be sufficient to prepare the surface for application of the chrome layer 40, but not so extensive that the hardened layer 50 becomes ineffective or is completely removed.

[0075] The method of manufacturing the formed rod 12 may include forming a hardened layer 50 on the outer surface 32 of the formed rod 12, and depositing a chrome layer 40 on the hardened layer outer surface 56, the hardened layer 50 being formed on the outer surface 32 of the formed rod 12. As previously described, the method may include a polishing step between forming the hardened layer 50 and depositing the chrome layer 40. The chrome layer 40 may be applied by an electroplating process.

[0076] As previously described, the screen cylinder 10 including the profiled rods 12 with the hardened layer 50 may be used to process solid suspensions of cellulose or other fibers in pulp in the paper industry, as previously described. However, the screen cylinder 10 may not be limited to use in the pulp and paper industry. For example, the screen cylinder 10 of the present disclosure with the hardened profiled rods 12 may be used to screen solid suspensions and / or slurries to remove oversized solid contaminants in mining and drilling applications, food preparation and processing operations, water treatment processes, coating operations, and other industries.

[0077] Reference again Figure 1 In some embodiments, a method of removing oversized solid contaminants from a slurry or solid suspension may include contacting the slurry or solid suspension with a screen cylinder 10. The screen cylinder 10 may include a plurality of forming rods 12 coupled to at least one support ring 14 and longitudinally aligned. The forming rods 12 may have any of the features or properties previously described herein. Figure 5 In some embodiments, each of the plurality of forming rods 12 may include an outer surface 32 facing away from at least one support ring 14, a first groove surface 34 extending from the outer surface 32 to the attachment end 30 of the forming rod 12, and a second groove surface 36 opposite the first groove surface 34 and extending from the outer surface 32 to the attachment end 30 of the forming rod 12. As previously described, each of the forming rods may include a hardened layer 50 integral with or disposed on at least a portion of the first groove surface 34 of each forming rod 12, the hardened layer 50 having a Vickers hardness value greater than the base metal 46, such as greater than or equal to 500 HV0.05, greater than or equal to 900 HV0.05, greater than or equal to 1000 HV0.05, greater than or equal to 1100 HV0.05, or even greater than or equal to 1200 HV0.05. The first groove surface 34 and the second groove surface 36 of a pair of forming rods 12 in a side-by-side arrangement (e.g., a pair of immediately adjacent forming rods 12) define a plurality of grooves 20 of the screen drum 10. Contact of the slurry or solid suspension with the screen drum may cause at least a portion of the slurry or solid suspension to pass through the slots 20. The method may also include collecting an acceptable portion of the slurry or solid suspension from the plurality of slots 20 of the screen drum 10. In some embodiments, the forming rods 12 may also include a chrome layer 40 disposed on the outer surface 32 of the forming rods 12 or on the hardened layer 50. In some embodiments, the method may also include removing at least a portion of the solid contaminants from the outer surface 32 of the plurality of forming rods 12. Example

[0078] Embodiments of the present disclosure will be further illustrated by the following examples, which should not be construed as limitations on the presently described disclosed and / or claimed embodiments.

[0079] Example 1

[0080] A plurality of stainless steel forming rods for screen cylinders were subjected to a nitrocarburizing process to produce a hardened layer integral with the surface of the forming rods. The base metal of the forming rods in Example 1 was 316L stainless steel. The nitrocarburizing process was accomplished by immersing the forming rods in a molten salt bath at a temperature ranging from 370°C to 540°C for a sufficient time to form a hardened layer. The salt bath included cyanate ions for providing nitrogen and carbonate ions for providing carbon. The nitriding process produced a compound layer and a diffusion zone extending from the compound layer further into the base metal.

[0081] For Examples 1 and 2, the thickness of the compound layer and diffusion zone of the nitrided sample was measured according to ASTM B487-85 (2007). These thicknesses were measured under a 1000x magnifying glass. The Vickers hardness value was measured according to ASTM E384-11e1 standard. For the diffusion zone in each nitrided rod, the Vickers hardness (HV) was measured on the transverse section of the molded rod with an indenter load of 0.05 kgf. For the compound layer, after the outer surface was lightly polished with a 1 micron polishing medium, the outer surface of the molded rod was hardness tested. The indenter load was 0.05 kgf again. The Vickers hardness measurement value was also converted to an approximate Rockwell hardness (HRC) value using ASTM E140-12be1 formula X1.1.1. The average thickness, average Vickers hardness, and average HRC of the compound layer and diffusion layer of the hardened molded rod of Example 1 are provided in Table 1. Table 1

[0082] In addition, the profiled rods of Example 1 were subjected to welding tests to evaluate the bonding of the welds between the profiled rods and the end flanges of the screen drum. Portions of the profiled rods of Example 1 were welded to the stainless steel flanges. No adhesion issues with the welds were observed.

[0083] The formed rods of Example 1 were also subjected to corrosion testing. In the first corrosion test, a subset of the formed rods of Example 1 were placed in water for a period of 20 days. After 1 day of immersion in water, no corrosion was evident on the samples. After the 20 day period, the portions of the formed rods of Example 1 that were immersed in water exhibited a layer of corrosion on the outer surface. Additionally, a second subset of the formed rods of Example 1 were exposed to ambient air. After 430 days, small areas of corrosion were exhibited on the outer surface of the formed rods.

[0084] Example 2

[0085] A second plurality of stainless steel forming rods for the screen cylinder is subjected to a nitrocarburizing process to produce a hardened layer that is integral with the surface of the forming rod. The base metal of the forming rod in Example 1 is 316L stainless steel. The nitrocarburizing process is accomplished by immersing the forming rod in a molten salt bath at a temperature of 370°C to 540°C for a sufficient time to form a hardened layer. The salt bath includes cyanate ions for providing nitrogen and carbonate ions for providing carbon. The nitrocarburizing process produces a compound layer and a diffusion zone extending further from the compound layer into the base metal. According to the method previously described in Example 1, the thickness of the diffusion zone and the compound layer, the Vickers hardness, and the HRC are determined for each sample forming rod. The average thickness, average Vickers hardness, and average HRC of the compound layer and the diffusion layer of the hardened forming rod of Example 2 are provided in Table 2. Table 2

[0086] The profiled rods of Example 2 were also subjected to welding tests to evaluate the bonding of the welds between the profiled rods and the end flanges of the screen drum. Portions of the profiled rods of Example 2 were welded to the stainless steel flanges. No bonding issues with the welds were observed.

[0087] The formed rods of Example 2 were also subjected to corrosion testing. In the first corrosion test, a subset of the formed rods of Example 2 were placed in water for a period of 20 days. After 2 days of immersion in water, no corrosion was evident on the samples. After the 20 day period, the portions of the formed rods of Example 2 that were immersed in water exhibited a layer of corrosion on the outer surface. Additionally, a second subset of the formed rods of Example 2 were exposed to ambient air. After 430 days, small areas of corrosion were exhibited on the outer surface of the formed rods.

[0088] Example 3

[0089] In Example 3, another batch of multiple stainless steel forming rods for screen cylinders were subjected to a nitriding process according to the NANO-S™ nitriding process provided by Nitrex Metals of Quebec, Canada, to produce a hardened layer that is integral with the base metal. The nitriding process produces a compound layer and a diffusion zone that extends from the compound layer further into the base metal. The thickness and Vickers hardness of the diffusion zone and compound layer of each sample forming rod of Example 3 were determined according to the method previously described in Example 1, and the results are provided in Table 3. Table 3

[0090] In addition, the surface roughness Ra of the outer surface hardened layer of the compound layer was measured to be 0.10 micrometers, which is comparable to the surface roughness of the bare untreated molded rod, which has a Ra of 0.09 micrometers.

[0091] Example 4

[0092] For Example 4, a plurality of stainless steel forming rods were subjected to a tungsten carbide HVOF process to coat the forming rods with a tungsten carbide coating. Thus, in Example 4, the hardened layer was a hard coating comprising tungsten carbide.

[0093] The thickness of the hard coating of Example 4 is measured according to ASTM B487-85 (2007). For Example 4, the thickness is measured at 500 times magnification. The Vickers hardness value is measured according to ASTM E384-11e1 standard. The Vickers hardness (HV) is measured with an indenter load of 0.1 kgf on the transverse section of the forming rod. The hardness test is carried out in an area without macropores or shrinkage of the hard coating. The Vickers hardness measurement value is also converted into an approximate Rockwell hardness (HRC) value using ASTM E140-12be1 formula X1.1.1. The average thickness, average Vickers hardness and average HRC of the hard coating on the forming rod of Example 4 are provided in Table 4 below. Table 4

[0094] The formed rod with the tungsten carbide coating of Example 4 exhibited a greater average hardness than the formed rods with the hardened layer integrated with the base metal of Examples 1 and 2. However, it was observed that the formed rod with the tungsten carbide coating applied by HVOF of Example 4 exhibited a greater surface roughness than the formed rods of Examples 1 and 2, for which the hardened layer was formed using a nitriding process to be integrated with the base metal. In addition, the thickness of the hardened layer (i.e., the tungsten carbide coating) of the formed rod of Example 4 was not as consistent as the thickness of the hardened layer of the formed rods of Examples 1 and 2.

[0095] In addition, for the molded rod of Example 4, a bonding test was performed on the interface between the base metal and the tungsten carbide coating using an interface indentation method. In the interface indentation method, Vickers indentation was applied to the interface between the base metal and the tungsten carbide coating using loads of 0.1 kgf and 0.5 kgf. In response to the interface indentation test, no obvious cracks were observed at the interface when the indentation load was 0.1 kgf, however, some small cracks were observed at the interface between the base metal and the tungsten carbide coating when the indentation load was 0.5 kgf.

[0096] Example 5

[0097] In Example 5, multiple rods of Example 4 with tungsten carbide coatings applied via HVOF were electroplated with chromium to produce a chromium layer. The chromium layer was applied on top of the tungsten carbide coating. For sample 5A, the electroplating process was carried out for a longer period of time, resulting in a thicker chromium layer. For sample 5B, the electroplating time was reduced, resulting in a thinner chromium layer. The average thickness of the tungsten carbide coating was determined. Due to the inconsistency of the electroplating process, the chromium layer thickness was measured in the thickest area of ​​the chromium layer, the thinnest area of ​​the chromium layer, and the middle thickness area of ​​the chromium layer for samples 5A and 5B. In addition, the Vickers hardness value of the tungsten carbide coating was measured according to the method previously described herein. The thickness and Vickers hardness values ​​of samples 5A and 5B are provided in Table 5. Table 5

[0098] Comparative Example 6

[0099] In Comparative Example 6, the Vickers hardness values ​​of a plurality of untreated formed rods whose base metal was 316L stainless steel and had no hardening layer or chrome plating were measured. The results of the Vickers hardness values ​​of the formed rods of Comparative Example 6 are provided in Table 6 below.

[0100] Comparative Example 7

[0101] For Comparative Example 7, a plurality of formed rods were electroplated with chromium to form a chromium layer, and there was no hardening layer between the base metal and the chromium layer. The Vickers hardness values ​​of the formed rods of Comparative Example 7 were determined according to the test method previously described herein. The Vickers hardness values ​​of the formed rods of Comparative Example 7 with the chromium layer and without the hardening layer are provided in Table 6. Since the thickness of the chromium layer applied by electroplating is not uniform, the Vickers hardness value of the chromium layer of each formed rod of Comparative Example 7 is determined at a first region having a thicker chromium layer, a second region having a medium-thick chromium layer, and a third region having a thinner chromium layer. Table 6

[0102] The hardened formed rods of Examples 1-5 all exhibited an average Vickers hardness greater than the average Vickers hardness of Comparative Example 6, which was an untreated formed rod. The average Vickers hardness of the hardened formed rods of Examples 1 and 3 to 5 were all comparable to or greater than the hardness of the formed rod coated with the chromium coating of Comparative Example 7. Thus, the hardness of the hardened formed rod treated by the methods disclosed herein can be substantially greater than the base metal and comparable to or greater than the hardness of a formed rod having only a chromium layer deposited thereon.

[0103] A first aspect of the present disclosure may be directed to a screen drum, which may include a plurality of forming rods, which are longitudinally aligned and are connected to at least one support ring at the attachment end of the plurality of forming rods. Each of the plurality of forming rods may include an outer surface, which faces away from at least one support ring, a first groove surface, which extends from the outer surface to the attachment end of the forming rod opposite to the outer surface, and a second groove surface, which is opposite to the first groove surface and extends from the outer surface to the attachment end of the forming rod. The first groove surface of a forming rod and the second groove surface of another adjacent forming rod may define a groove. Each of the plurality of forming rods may also include a hardened layer that is integrated with or disposed on at least a portion of the first groove surface of the forming rod. Determined according to ASTM E384-11e1, the Vickers hardness value of the hardened layer may be greater than or equal to 500HV0.05.

[0104] A second aspect of the present disclosure may include the first aspect, wherein the hardening layer may be provided at some portions of the second groove surface, the outer surface, or both of each of the forming rods.

[0105] A third aspect of the present disclosure may include any one of the first aspect or the second aspect, wherein the hardening layer may be provided on an entire outer peripheral surface of each of the forming rods, the entire outer peripheral surface including at least the outer surface, the first groove surface, and the second groove surface.

[0106] A fourth aspect of the present disclosure may include any one of the first to third aspects, wherein the hardened layer may have a hardened layer outer surface having a morphology that is consistent in size within a tolerance range of less than or equal to 9 micrometers (μm).

[0107] A fifth aspect of the present disclosure may include any one of the first to fourth aspects, wherein the Vickers hardness value of the hardened layer may be greater than or equal to 900 HV0.05 as determined according to ASTM E384-11e1.

[0108] A sixth aspect of the present disclosure may include any one of the first to fifth aspects, wherein the conductivity of the hardened layer may be the same as the conductivity of a base metal of the plurality of formed rods.

[0109] A seventh aspect of the present disclosure may include any one of the first to sixth aspects, wherein a base metal of each of the plurality of formed rods may include stainless steel.

[0110] An eighth aspect of the present disclosure may include any one of the first to seventh aspects, wherein a base metal of each of the plurality of forming rods may be non-annealed.

[0111] A ninth aspect of the present disclosure may include any one of the first to eighth aspects, further comprising a chrome layer provided on an outer surface of the formed rod or on the hardened layer.

[0112] A tenth aspect of the present disclosure may include the ninth aspect, wherein a thickness of the chrome layer of each of the formed rods may decrease from an outer surface toward an attachment end of each of the formed rods.

[0113] An eleventh aspect of the present disclosure may include any one of the first to tenth aspects, wherein the hardened layer may include a surface treatment layer of a base metal of the formed rod.

[0114] A twelfth aspect of the present disclosure may include the eleventh aspect, wherein a depth of the surface treatment layer of the base metal may be greater than or equal to 5 micrometers.

[0115] A thirteenth aspect of the present disclosure may include any one of the eleventh aspect or the twelfth aspect, wherein the surface treatment layer may include at least nitride ions.

[0116] A tenth aspect of the present disclosure may include any one of the first to eighth aspects, wherein an outer surface of each of the plurality of formed rods may include a hardened layer, and the chrome layer is disposed on the hardened layer.

[0117] A fifteenth aspect of the present disclosure may include any one of the first to tenth aspects, wherein the hardening layer may be a hard coating layer applied to at least a portion of a surface of the first groove of the forming rod.

[0118] A sixteenth aspect of the present disclosure may include the fifteenth aspect, wherein the hard coating layer has a thickness greater than or equal to 5 micrometers, or from 5 micrometers to 300 micrometers.

[0119] A seventeenth aspect of the present disclosure may include any one of the fifteenth aspect or the sixteenth aspect, wherein the hard coating may include tungsten carbide, chromium carbide, titanium nitride, chromium nitride, electroless nickel, ceramic coating, aluminum oxide, 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.

[0120] An eighteenth aspect of the present disclosure may include any one of the first to seventeenth aspects, wherein the screen drum is operable to separate solid contaminants from the solid suspension.

[0121] The nineteenth aspect of the present disclosure may be directed to a profiled rod for a screen drum, which is used to separate solid contaminants from solid suspensions. The profiled rod may include an attachment end and an outer surface disposed at an end opposite to the attachment end, a first groove surface extending from the outer surface to the attachment end of the profiled rod, a second groove surface opposite to the first groove surface and extending from the outer surface to the attachment end, and a hardened layer integrated with at least a portion of the first groove surface, a portion of the second groove surface, or both. The Vickers hardness value of the hardened layer may be greater than or equal to 500 HV0.05 as determined according to ASTM E384-11e1.

[0122] A twentieth aspect of the present disclosure may include the nineteenth aspect, wherein when a plurality of forming bars are arranged longitudinally and side by side, a first groove surface of one forming bar and a second groove surface of another immediately adjacent forming bar may define a groove.

[0123] A twenty-first aspect of the present disclosure may include any one of the nineteenth or twentieth aspects, wherein the hardening layer may be provided on the entire outer peripheral surface of each of the forming rods. The entire outer peripheral surface may include at least 80% of the outer surface, the first groove surface, and the second groove surface.

[0124] A twenty-second aspect of the present disclosure may include any one of aspects 19 to 21, wherein the hardened layer may have a hardened layer outer surface having a morphology that is consistent in size within a tolerance range of less than or equal to 9 micrometers (μm).

[0125] A twenty-third aspect of the present disclosure may include any one of the nineteenth to twenty-second aspects, wherein the Vickers hardness value of the hardened layer may be greater than or equal to 900 HV0.05 as determined according to ASTM E384-11e1.

[0126] A twenty-fourth aspect of the present disclosure may include any one of the nineteenth to twenty-third aspects, wherein the conductivity of the hardened layer may be the same as the conductivity of a base metal of the plurality of formed rods.

[0127] A twenty-fifth aspect of the present disclosure may include any one of the nineteenth to twenty-fourth aspects, wherein the base metal of each of the plurality of formed rods may include stainless steel.

[0128] A twenty-sixth aspect of the present disclosure may include any one of the nineteenth to twenty-fifth aspects, wherein the base metal of each of the plurality of formed rods may be non-annealed.

[0129] A twenty-seventh aspect of the present disclosure may include any one of the nineteenth to twenty-sixth aspects, further comprising a chrome layer disposed on the outer surface or on the hardened layer.

[0130] A twenty-eighth aspect of the present disclosure may include the twenty-seventh aspect, wherein the thickness of the chrome layer may decrease from the outer surface toward the attachment end of the profiled rod.

[0131] A twenty-ninth aspect of the present disclosure may include any one of the nineteenth to twenty-eighth aspects, wherein the hardened layer may include surface treatment of a base metal of the formed rod up to a certain depth within the base metal.

[0132] A thirtieth aspect of the present disclosure may include the twenty-ninth aspect, wherein a depth of the hardened layer may be greater than or equal to 5 micrometers.

[0133] A thirty-first aspect of the present disclosure may include any one of the nineteenth aspect or the thirtieth aspect, wherein the hardened layer may include at least nitride ions.

[0134] A thirty-second aspect of the present disclosure may include any one of the nineteenth to twenty-eighth aspects, wherein the outer surface may include a hardened layer, and the chrome layer is disposed on top of the hardened layer.

[0135] A thirty-third aspect of the present disclosure may include any one of the nineteenth to twenty-eighth aspects, wherein the hardening layer may be a hard coating layer applied to a base metal.

[0136] A thirty-fourth aspect of the present disclosure may include the thirty-third aspect, wherein the hard coating layer has a thickness greater than or equal to 5 microns, or from 5 microns to 300 microns.

[0137] A thirty-fifth aspect of the present disclosure may include any one of the thirty-third aspect or the thirty-fourth aspect, wherein the hard coating may include tungsten carbide, chromium carbide, titanium nitride, chromium nitride, electroless nickel, ceramic coating, aluminum oxide, 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.

[0138] A thirty-sixth aspect of the present disclosure may include any one of the nineteenth to thirty-fifth aspects, and may be directed to a screen cylinder including the forming rod of any one of the nineteenth to thirty-fifth aspects.

[0139] A thirty-seventh aspect of the present disclosure may include the thirty-sixth aspect, wherein the screen cylinder comprises a plurality of profiled bars longitudinally aligned and coupled to at least one support ring at attachment ends of the plurality of profiled bars.

[0140] The thirty-eighth aspect of the present disclosure may be directed to a method for manufacturing a hardened profiled rod for a screen drum. The method may include providing a profiled rod, the profiled rod may include an attachment end and an outer surface facing a direction opposite to the attachment end, a first groove surface extending from the outer surface to the attachment end of the profiled rod, and a second groove surface opposite to the first groove surface and extending from the outer surface to the attachment end. The method may also include forming a hardened layer on at least a portion of the first groove surface or integrally therewith, wherein the Vickers hardness value of the hardened layer may be greater than or equal to 500 HV0.05 as determined according to ASTM E384-11e1.

[0141] A thirty-ninth aspect of the present disclosure may include the thirty-eighth aspect, further comprising a chrome layer on an outer surface of the formed rod or on the hardened layer.

[0142] A fortieth aspect of the present disclosure may include any one of the thirty-eighth aspect or the thirty-ninth aspect, including forming a hardened layer on some portions of the outer surface, the second groove surface, or both.

[0143] A forty-first aspect of the present disclosure may include any one of aspects 38 to 40, wherein forming the hardened layer may include subjecting at least a first groove surface of the formed rod to a surface treatment, wherein one or more chemical compounds diffuse into the base metal at the first groove surface.

[0144] A forty-second aspect of the present disclosure may include the forty-first aspect, wherein the surface treatment may include contacting at least a portion of the formed rod with a nitrogen-containing gas or a nitrogen-containing liquid bath at a temperature below the annealing temperature of the base metal and at a pressure sufficient to diffuse nitrogen or a nitrogen-containing compound into the base metal.

[0145] A forty-third aspect of the present disclosure may include any one of the thirty-eighth to fortieth aspects, wherein forming the hardened layer may include applying a coating to at least a first groove surface of the forming rod.

[0146] A forty-fourth aspect of the present disclosure may include the forty-third aspect, wherein applying the coating to at least the first slot surface may include a thermal spray process.

[0147] A forty-fifth aspect of the present disclosure may include the forty-fourth aspect, wherein the thermal spray process may include a tungsten carbide high velocity oxygen fuel (HVOF) process.

[0148] A forty-sixth aspect of the present disclosure may include the forty-third aspect, wherein forming the hardened layer may include applying a ceramic coating film to one or more surfaces of the forming rod and firing the forming rod at a temperature sufficient to form the ceramic coating and bond the ceramic coating to the base metal of the forming rod.

[0149] A forty-seventh aspect of the present disclosure may include any one of the thirty-eighth to forty-sixth aspects, including forming a hardened layer on an outer surface of the formed rod, and depositing a chrome layer on an outer surface of the hardened layer formed on the outer surface of the formed rod.

[0150] A forty-eighth aspect of the present disclosure may include the forty-seventh aspect, wherein the thickness of the chrome layer may decrease from the outer surface toward the attachment end of the profiled rod.

[0151] The forty-ninth aspect of the present disclosure may be directed to a method for removing solid contaminants from a solid suspension. The method may include contacting the solid suspension with a screen drum. The screen drum may include a plurality of profiled rods connected to at least one support ring and aligned longitudinally. Each of the plurality of profiled rods may include: an outer surface away from at least one support ring, a first groove surface extending from the outer surface to an attachment end of the profiled rod opposite to the outer surface, a second groove surface opposite to the first groove surface and extending from the outer surface to the attachment end of the profiled rod, and a hardened layer integral with or disposed on at least a portion of the first groove surface of each profiled rod. The Vickers hardness value of the hardened layer may be greater than or equal to 500HV0.05 as determined according to ASTM E384-11e1. The first groove surface and the second groove surface of the profiled rods paired side by side may define a plurality of grooves of the screen drum, and contact of the solid suspension with the screen drum may cause at least a portion of the solid suspension to pass through these grooves. The method may also include collecting acceptable solid suspensions from a plurality of grooves of the screen drum.

[0152] A fiftieth aspect of the present disclosure may include the forty-ninth aspect, further comprising removing at least a portion of the solid contaminants from the outer surfaces of the plurality of formed rods.

[0153] A fifty-first aspect of the present disclosure may include any one of the forty-ninth aspect or the fiftieth aspect, wherein each of the plurality of formed rods may include a chrome layer deposited on an outer surface of the formed rod or on the hardened layer.

[0154] A fifty-second aspect of the present disclosure may include any one of the forty-ninth to fifty-first aspects, wherein the hardened layer may include a surface treatment layer of a base metal of the formed rod.

[0155] A fifty-third aspect of the present disclosure may include any one of aspects 49 to 51, wherein the hardening layer may be a hard coating applied to at least a portion of the surface of the first groove of the forming rod.

[0156] Although various embodiments of the forming rod 12 for the screen drum 10 and methods of making and using the forming rod 12 have been described herein, it should be understood that each of these embodiments and techniques can be contemplated for use alone or in combination with one or more embodiments and techniques. It will be apparent 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 claimed subject matter. Therefore, this specification is intended to cover modifications and variations of the various embodiments described herein, as long as these modifications and variations fall within the scope of the appended claims and their equivalents.

Claims

1. A screen drum comprising: a plurality of formed rods, the plurality of formed rods being longitudinally aligned and coupled to at least one support ring at their attachment ends, each of the plurality of formed rods comprising: an outer surface facing away from the at least one support ring; a first groove surface extending from the outer surface to an attachment end of the profiled rod opposite the outer surface; a second groove surface opposite the first groove surface and extending from the outer surface to the attachment end of the shaped rod, wherein the first groove surface of one shaped rod and the second groove surface of another immediately adjacent shaped rod define a groove; and A hardened layer, the hardened layer is disposed on at least a portion of the first groove surface or the second groove surface of the forming rod, and the Vickers hardness value of the hardened layer is greater than or equal to 500 HV0.05 as determined according to ASTM E384-11e1, The groove width of the groove varies along the longitudinal length of the forming rod within a tolerance of less than or equal to 15 microns, wherein the groove width is the shortest distance between a first groove surface of one forming rod and a second groove surface of another adjacent forming rod.

2. The sieve drum according to claim 1, characterized in that , the hardened layer is arranged on the outer surface of each of the forming rods.

3. The sieve drum according to any one of claims 1 or 2, characterized in that The hardened layer is provided on the entire outer peripheral surface of each of the forming rods, the entire outer peripheral surface including at least the outer surface, the first groove surface, and the second groove surface.

4. The sieve drum according to any one of claims 1 to 3, characterized in that The hardened layer has a hardened layer outer surface having a topography with a size that is consistent within a tolerance range of less than or equal to 9 micrometers (μm).

5. The sieve drum according to any one of claims 1 to 4, characterized in that Determined according to ASTM E384-11e1, the Vickers hardness value of the hardened layer is greater than or equal to 900 HV0.

05.

6. The sieve drum according to any one of claims 1 to 5, characterized in that The base metal of each of the plurality of formed rods includes stainless steel.

7. The sieve drum according to any one of claims 1 to 6, characterized in that The base metal of each of the plurality of formed rods is non-annealed.

8. The sieve drum according to any one of claims 1 to 7, characterized in that Also included is a chrome layer disposed on the outer surface of the profiled rod or on the hardened layer.

9. The sieve drum according to claim 8, characterized in that , the thickness of the chrome layer of each of the forming rods decreases from the outer surface toward the attachment end of each of the forming rods.

10. The sieve drum according to any one of claims 1 to 9, characterized in that An outer surface of each of the plurality of formed rods includes the hardened layer, and a chrome layer is disposed on the hardened layer.

11. The sieve drum according to any one of claims 1 to 10, characterized in that The hardening layer is a hard coating applied to at least a portion of the first groove surface of the forming rod.

12. The sieve drum according to any one of claims 1 to 11, characterized in that The hard coating has a thickness greater than or equal to 5 micrometers, or from 5 micrometers to 300 micrometers.

13. The sieve drum according to any one of claims 11 or 12, characterized in that The hard coating includes tungsten carbide, chromium carbide, titanium nitride, chromium nitride, electroless nickel, ceramic coating, aluminum oxide, composite coating or a combination thereof.

14. The sieve drum according to any one of claims 11 to 13, characterized in that The hard coating is a ceramic coating.

15. The sieve drum according to any one of claims 1 to 14, characterized in that The conductivity of the hardened layer is within 10% of the conductivity of a base metal of a plurality of the formed rods.

16. The sieve drum according to any one of claims 1 to 15, characterized in that The second groove surface includes a nose protruding outwardly from the second groove surface toward another immediately adjacent first groove surface of the forming rod, and wherein the hardened layer is formed on the nose of the second groove surface and a portion of the first groove surface opposite to the nose.

17. The sieve drum according to any one of claims 1 to 16, characterized in that The screen drum is operable to separate solid contaminants from a solid suspension.

18. The sieve drum according to any one of claims 1 to 17, characterized in that The groove width is from 0.08 mm to 1.5 mm.

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