JP2002503774A - Screen cylinder with high ratio open area - Google Patents

Abstract

(57) Abstract: A screen cylinder (10) and a method of manufacturing the same are disclosed. The desired inlet (29) and outlet (31) side profiles of the screen cylinder are formed on each side, such as the precursor metal plate (40). The profile consists of a series of grooves (46) formed along each top (42) and bottom (44) side of the metal plate (40). The grooves (46) do not extend through the metal plate (40) but are substantially superimposed on one another from the side of one metal plate to the side of the other metal plate. The metal plate (40) is formed into the desired shape and a slot (62) is cut into the metal plate (40) to communicate with the slot (62) that functions as a filtration media between the inlet and outlet profiles.

Description

DETAILED DESCRIPTION OF THE INVENTION

TECHNICAL FIELD The present invention relates to screens or screen cylinders, and more particularly to screens used in pressure sieving equipment for removing contaminant particles from papermaking raw materials.

BACKGROUND OF THE INVENTION A high pressure sieving apparatus of the type shown, for example, in US Pat. Used in preparation for A suspension of liquid and paper fibers containing various undesirable reject or contaminant particles is fed to the inlet of a device such as disclosed in the above-mentioned patent. The suspension is then applied to an annular cylindrical shaped screen with specially designed slots or perforations. Typically, the paper stock is fed to a vertically oriented cylindrical screen and rejects are withdrawn from one end of the screen, while receivers pass through slots or perforations in the screen and are external to the screen. Collected in places. A rotating foil or vane is usually positioned at or near the inner surface of the screen to reduce blockage of the screen slots or holes.

[0003] Typically, screen cylinders of the type described above are machined with the required slots or grooves in a flat plate of a metallic material such as stainless steel, and the flat plate is rolled into the shape of a cylinder and rolled. It is formed by welding the plates at the joint ends to form a weld seam. Thereafter, an end ring formed from the bar is rolled, welded at each end, and then attached to the cylindrical plate at each end by welding. In addition, one or more intermediate reinforcing rings formed from the rolled bars are attached by welding at longitudinally spaced locations on the outer surface of the rolled screen plate. An example of a cylinder screen manufactured in this manner was disclosed on April 12, 1977 by Hat.
No. 4,017,387 issued to ton and Lehman.

[0004] As a result of holes, reduced areas, or slot-shaped openings that are cut or formed in the plate in the flat state, complications arise in manufacturing the screen cylinder in the manner described above. These openings tend to be inherently distorted by the rolling process. In addition, the rolling process is a slotted area and an unslotted area because a number of slots are formed closely together and each slot usually ends at a common location on the plate so as to form a row of slots separated by land areas. Due to the difference in strength between the two, it becomes inherently uneven in the circumferential direction of the plate. It is therefore believed that stress concentration points tend to form at the end of the slot during rolling with different bending at these locations.

[0005] To avoid these problems, the manufacturer, Chupk, on November 12, 1991, hereby incorporated by reference required to complete this disclosure.
U.S. Pat. No. 5,044, a to Consiner and Vitori
A seamless screen cylinder with a laser cutting aperture as shown in US Pat. No. 6,537 was made. The integral seamless cylinder body is disclosed in US Pat.
No. 46,537, essentially stress-free and formed without weld seams,
Slots are provided by laser cutting to form sieving openings. The cylinder body is formed by cold working a seamless material by using a centrifugal casting or roller extrusion process. In some cases, openings or slots are formed by laser cutting techniques, by focusing of the laser cutting beam, or by directing this laser beam energy at the exit surface to the entrance surface. The cylinder and / or beam may be moved with respect to each other to create a slot.

[0006] Alternatively, it is known to make a screen cylinder having a plurality of parallel bar screen elements mounted on a cross bar to form a screen area and define a screen slot therebetween. . One example of such a screen cylinder is described in U.S. Pat.
72, 095. The screen elements or bars are arranged in parallel adjacent spaced relation to define a screen slot having a predetermined slot entrance width. The end ring is welded to the axial end of the bar. A longitudinally spaced reinforcement ring is welded to the outside of the bar.

[0007] To increase the capacity and efficiency of screen cylinders of the type described above to screen debris or impurities from the suspension, the bar is machined or formed by drawing or extruding through a die to provide the desired crossing. Give the surface shape. An example of a screen bar having a different shape was found on October 26, 1993 in Eino.
This is shown in U.S. Pat. No. 5,255,790 to der and Knodel. Such a bar or wedge wire has a generally wedge shape with a wide entrance end and a narrow exit end.

[0008] Screen cylinders made in accordance with the above can alter spaced screens due to the inherent movement and misalignment between screen bars. In addition, the use of numerous wedges as well as machined holding racks or mandrels increases material processing costs and contributes to variations in screen slot spacing.

[0009] Therefore, there is a need for an improved pressure screen design and method of manufacture that facilitates manufacture and ensures structural stability and dimensional accuracy during and after manufacture.

DISCLOSURE OF THE INVENTION [0010] Applicants have discovered that after the screen material has been formed into its final form,
Creating a screen cylinder that separates debris and other impurities from a suspension containing paper fibers that combines the advantages of a screen element or bar with the desired cross-sectional shape and screen slot shape formed between the bars. Method developed. The screen cylinder according to the invention is characterized by providing a high opening area for a given slot width and slot spacing.

The method includes machining a first continuous axial groove shape on an inlet side of the metal plate, machining a second continuous axial groove shape on an outlet side or a receiving side of the metal plate, Rolling to the desired diameter, cutting the plate to the desired circumferential length, welding the reinforcing ring to the exit side of the plate, welding the end ring to the axial end of the plate, almost continuous slots Into the plate and connecting the inlet and outlet grooves.

A plate material, typically a stainless steel having a desired thickness, is first provided. Subsequently, a parallel groove having a first desired shape is machined on the inlet side of the plate by conventional means. The groove extends approximately the entire length of the plate. The plate is turned over and a substantially parallel groove having a second desired shape is machined on the exit side of the plate. The outlet groove is machined to substantially match the inlet groove on the opposite side of the plate. The inlet and outlet shapes may be formed by means known to those skilled in the art, for example, by milling or stamping.

[0013] To form a type of cylindrical pressure screen in which the flow of the papermaking stock suspension is from inside the basket-shaped screen to outside of the screen, the grooved plate is oriented with its inlet face radially inward. Rolled or bent to the desired diameter.
If desired, a grooved plate may be formed around the mandrel. A ring formed from a rolled stainless steel bar or other material is fixed to the shaft end of the rolled plate by welding or the like. A support ring made of a rolled stainless steel bar raw material is fixed at intervals in the outlet side longitudinal direction of the rolled plate by welding or the like.

A longitudinally extending screen slot is cut through the plate so as to penetrate the plate from the exit side of the rolled plate to the entrance side of the rolled plate. The screen slots define fluid flow passages through the rolled plate that connect the correspondingly arranged grooves on the outlet side of the plate and the grooves on the inlet side. The screen slots extend approximately the entire length of the rolled plate. An uncut or interrupted portion may be provided to travel from the axial length end of the slot to the other end. These uncut portions act as bridges or spacers connecting solid material extending between the slots to improve the overall structural integrity of the screen cylinder and maintain accurate slot width dimensions.

As used throughout the specification and claims, the grooves and slots are said to extend substantially along the entire longitudinal dimension of the plate. Its dimensions correspond to the axial direction when the plate is finally formed as a cylinder. In this context, "substantially" means that the grooves and slots extend the entire length along the axial direction (100% of the axial length), or that the grooves and slots extend almost the entire length along the axial direction. .

The screen slots are preferably formed by laser cutting,
It may be formed by any suitable means such as water jet, electron beam, electron discharge machining, or other machining or cutting methods.

Although the above-described pressure screen cylinder design and manufacturing method may be used to create specific baskets for pulp and paper sieving, such screen cylinders are limited to this use only. Absent.

Accordingly, it is an object of the present invention to provide a method for making a screen cylinder and a screen made by the method. It is another object of the present invention to provide a method of making a screen cylinder having a maximum open area with a predetermined circumferential slot spacing.

A particular object of the present invention is to form an individual sieving element having the sieving advantages of a wedge wire screen (large open area) cylinder, but with one of the slot dimensions more accurately. The object is to provide a screen cylinder that is more easily maintained and has a high degree of mechanical integrity.

It is another object of the present invention to provide a method of making a screen cylinder that produces dimensionally precise screen slots. It is another object of the present invention to provide an improved pulp slurry screen by fitting in a cylinder according to the present invention.

Another object of the invention is to provide a screen screen in which the slots are cut later in the manufacturing method.
To provide a cylinder. Another object of the invention is to provide an open area for passing the receiving slurry through the slot,
The aim is to provide an open area that is obstructed by the reinforcing ring even in these areas. The received slurry easily flows axially to the receiving chamber along the grooves on the receiving side of the plate.

Referring to the drawings, and in particular with reference to FIG. 1, there is shown a screen cylinder 10 made in accordance with the present invention. The screen cylinder includes a top end ring 20 and a bottom end ring 22, each serving as axial end reinforcement for a number of spaced axially extending screen bars 25. Openings 27 are provided between adjacent screen bars 25 and serve to allow the ingress and egress of fluids while performing sieving or filtering functions.

Reinforcing rings 14, 16, 18 are axially spaced around the perimeter of screen bar 25 to provide support and stability for the screen cylinder.

As shown, the screen cylinder is such that the pulp suspension is received inside the screen cylinder as indicated by arrow 29 and the receptacle is between the screen bars as indicated by arrow 31. It is of the type that flows through an opening. Rejects or objects that do not pass through the opening exit the cylinder at an exit point (not shown) communicating with the cylinder interior space.

As in the prior art, one or more vanes are mounted inside the cylinder and rotate the pulp suspension as the vanes sweep along the entrance surface of the screen bar 25 and thereupon. Generates shearing force. One type of operation of a commercially successful rotary sieving apparatus is shown in U.S. Pat. No. 4,267,035. The entire disclosure of this patent is mentioned here so that the principle of operation need not be repeated here.

FIG. 2 shows a plate 40 made of a rigid and durable material such as a metal material including stainless steel, aluminum, titanium, and alloys thereof.
Currently, it is desirable to use a stainless steel plate having a thickness of about 1 / 4-3 / 4 inch, most preferably about 3/8 inch. The length (axial in relation to the forming cylinder) and width of the plate are selected such that a screen cylinder having the required circumference and axial length is formed from the plate.

The plate has a top surface that is ultimately formed and used as the entrance surface of the screen cylinder. The exit surface of the screen cylinder corresponds to the bottom or lower side 44 of the plate 40.

The plate is used to form a series of axially extending screen bars 25 and intervening openings 27 described below. As shown schematically in FIG. 4, a number of longitudinal (or axially extending) grooves 46 are formed in the top surface 42 of the plate.
These grooves can be of any of a myriad of possible configurations. Everything is designed to create the desired contour for the entrance surface of the screen cylinder.

One such configuration is shown in FIGS. There, the grooves are indicated generally by the reference numeral 46. Groove 46 is more particularly comprised of a ramp 48, a relatively flat portion 50, and a lower ramp 52. The connection or bridge adjacent to the pair of grooves is a land portion 54 that is processed as described below.

A variety of different profiles are provided on the surface 42, and although it is presently desirable to provide a series of grooves 46 similar to that shown in FIG. 5, an actual flat profile surface may be provided. Will be understood by those skilled in the art.

The grooves 46 may be formed in the plate surface by conventional techniques such as milling, plasma, dry or other etching methods, laser cutting, punching, extruding, or casting. The groove 46 is partially cut or formed in the thickness of the plate from the top surface 42 to the bottom surface 44.

3 and 5, the bottom surface 44 is provided with a plurality of grooves 60 extending along the length (axial) direction, and communicates with a groove 46 provided on the top side of the plate when other manufacturing steps are completed. . Grooves 60 may be provided in the bottom surface by similar conventional means as described above in connection with the formation of grooves in top surface 42 of the plate. The grooves 60 do not extend through the entire thickness of the plate and are separated from one another by solid parts 61. Land portion 54 prevents communication between grooves 60 and 46.

The grooves 46, 60 taken together define a surface profile intended for the entrance and exit surfaces of the screen cylinder. Once the desired contour has been provided, the plate is rolled to the desired cylindrical shape corresponding to the desired shape of the final screen cylinder. The widthwise boundaries of the plates are fixed together and are defined in the cylinder by brazing or welding. Perhaps the widthwise end may be fixed to an axially extending stabilizer bar or the like.

Once the contoured plate has been rolled into the desired cylindrical shape, it can be made available for further use as required by the customer, or the hardness or metal hardness of the metal, if desired. It may be treated by a surface treatment that improves other properties. For example, the cylinder thus formed may be cured by dropping, flame, induction, or other conventional curing treatments.

After forming the cylinder from the contoured plates, the outer reinforcement ring, top support ring 20, and bottom support ring 22, as shown in FIG. 1, are fixed to the assembly and brazed or welded. Provide structural support to the cylinder as described by Preferably, at this point, the land portion 54 of the entrance surface is laser cut to communicate with the groove 60 on the exterior or receiving surface. This is best understood in connection with FIG. 5, where the slots 62 are shown in phantom. Slots 62 are provided in the land portion 54 of the entrance surface. Preferably, a laser is used to cut the slot 62.

A CO ₂ laser and a YAG laser are mentioned as typical laser cutting tools to be used for cutting the slot 62. However, other methods may be used, such as E-beam, electronic discharge machining (EDM), water jet, acid etching, or other etching methods. Importantly, the communication between the inlet and outlet surfaces is provided by slots 62.

In FIG. 6, a plurality of screen bars 25 are shown. There, the groove 46 on the inlet side of the cylinder communicates with the receiving groove 60 through the slot 62. As shown, the receiving side of the screen bar is secured to the reinforcing ring 16 at a solid portion 61. The inlet profile consists of a ramp 48, a plane 60, and a lower ramp 52 (inclined towards the receiving side). The receiving side includes a major cut defined by the groove 60.

In FIG. 8, a short bridge 80 is provided along a particular axial length of the slot 62. These bridges are the uncut portions of the slot that provide the remaining small solid connection between adjacent screen bars, guaranteeing the dimensional accuracy of the slot and stabilizing the cylindrically shaped assembly.

In FIG. 7, only one support ring is shown, but a simplified modification of the completed basket assembly and only a plurality of screen bars shown for ease of understanding is shown. Have been. The screen cylinder has a plurality of axially extending screen bars 25. The inlet face or inlet face contour 42 communicates with the outlet face or receiving contour 44 through a slot 62.

Another embodiment is shown in FIG. 9, where the entrance surface 42 of the screen bar is shown. Here, the slot 62 is formed so as to provide a variable width direction dimension. As shown, the slot 62 has a first width dimension 63 on the top surface in the axial direction.
With a second wide dimension given at the bottom. Varying the width of the illustrated slots is advantageous, for example, where increased concentrations of contaminant particles or the like in the pulp suspension occur toward the top of the screen cylinder. The narrow width of the slots at this level, ie at the level of the cylinder, reduces contaminants that may pass through during the receiving stream.

It should be noted that one advantage of the method and the composite structure illustrated here is that the slots can be provided along substantially the entire length of the precursor metal plate. Currently, plate materials suitable for use are Armco's "Nitronic33".
Is a hard stainless steel. It is a low wear austenitic stainless steel with a high wear resistance of about 95 Rockwell B hardness. An advantage of the present invention is that very hard or otherwise difficult-to-machine materials can be used as plates.

[0042] The method of the present invention can be used with 0.052 mm (0.002 inch) or 0.89 mm (
It has the advantage that the slots can be formed over a relatively wide range of slot widths of 0.035 inches or more. In one example, the width of the laser cutting slot was about 0.25 mm (0.010 inches). The thickness of the plate was 7.87 mm (0.31 inch) and the receiving side groove 60 (shown in FIG. 5) was about 0.04 mm (0.025 inch). In one embodiment, the slots 62 are spaced at a density of about six per straight inch.

By using the method described above, a cylindrical screen having a sieving element resembling a wedge wire is formed, so that the screen itself is precisely aligned during manufacture and thereafter in the wedge wire. It approximates a wedge wire screen without the specific drawbacks of the screen, including the difficulty in maintaining the screen. In this way,
The advantages of this screen product are the provision of a continuous axial slot which allows operation at speeds as low as 10 m / s to as high as 25 m / s or more, based on consistency requirements, precise slot width, high mechanical strength only Not including the exact mechanical appearance of the inlet and outlet surfaces. The fact that the material of the plate is maintained by welding at the end ring and the reinforcing ring means that the material removed, such as by laser cutting, is kept separate wedges maintained by welding between the axial bar and the reinforcing ring. It is similar to a wire in that it produces a substantially independent axial bar.

Although the present invention has been described in connection with cutting the slots 62 into plates after the plates have been formed into the desired cylindrical shape, the slots 62 may be formed into flat plates (shown in FIGS. 3 and 4). It may be formed. As a practical matter, forming the slots after giving the plate a cylindrical shape is preferred if the slots are not cut before rolling, as the plate integrity is better preserved. In addition, rings 14, 16
, 18 and the top surface 20, bottom surface 22 to cut the slot after reinforcing the cylinder greatly enhances the structural stability of the whole assembly and the dimensional accuracy of the slot.

[Brief description of the drawings]

FIG. 1 is a perspective view of a screen cylinder made according to the present invention.

FIG. 2 is a partially broken top view of a plate that can be used to form the screen cylinder of the present invention.

FIG. 3 is a partial cutaway plan view of the plate shown in FIG. 2, showing that the screen cylinder will eventually be on the receiving side of the screen cylinder during the first step of the manufacturing method in which it is made; .

FIG. 4 is a partially cutaway top view of the plate shown in FIG. 3, showing that it will end up on the inlet side of the screen cylinder.

5 is an enlarged cross-sectional view of the plate shown in FIG.

FIG. 6 is an enlarged cross-sectional view of a portion of the screen cylinder shown in FIG. 1 in a final assembly process.

FIG. 7 is a simplified perspective view of the screen cylinder during the assembly phase shown in FIG. 6, with the axially extending screen bar and a portion of the transverse support ring more clearly shown;

FIG. 8 is a simplified cross-sectional view taken along the line 8-8 in FIG. 6;

FIG. 9 is an enlarged partial cross-sectional view showing an inlet side of another embodiment of the screen cylinder.

[Procedural Amendment] Submission of translation of Article 34 Amendment of the Patent Cooperation Treaty

[Submission date] February 17, 2000 (2000.2.17)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

──────────────────────────────────────────────────の Continued on the front page (71) Applicant 605 Clark Street, P.E. O. Box 160, Middletown, Ohio 45042, United States of America (72) Inventor Seyfert, Peter 45042, Ohio, United States 4502 Middletown, Cloister Cliffs Drive 6705 F-term (reference) 4L055 CB26 FA22 CB31 FA22CB

Claims (42)

[Claims] 1. A screen having an inlet side and a receiving side comprising the following steps:
How to form a plate. (A) providing a plate material having top and bottom surfaces and length and width directions; (b) forming a desired contour of a long parallel channel on one or both of said surfaces, The groove extends along substantially the entire length of the plate, leaving the remaining plate material between opposing grooves or between the groove and the opposing surface; and (c) substantially remaining the full length of the contour in the remaining plate material. Forming a series of slots extending along the inlet and communicating between the inlet side and the receiving side. 2. The screen material of claim 1, wherein said plate material is provided with a cylindrical shape to form a screen cylinder having an inlet side and a receiving side, said parallel grooves extending axially. the method of. 3. The method of claim 1, wherein said step (b) comprises forming said groove along said entire length. 4. The method of claim 1, wherein step (c) comprises forming the slot along the entire length of the contour. 5. A method for forming a cylindrical screen having a pulp suspension inlet side and a pulp suspension receiving side comprising the following steps. (A) providing a plate material having a top surface and a bottom surface and a length direction and a width direction; and (b) along one of the top surface or the bottom surface and substantially along the length of the plate. (C) receiving a desired pulp suspension extending on the other of said top or bottom surface and substantially along the length of said plate. Forming a side profile; (d) forming a series of slots extending along the entire length of the plate material to communicate between the pulp suspension inlet side and the pulp suspension receiving side. (E) providing the plate material with a cylindrical shape to form a cylindrical screen having a pulp suspension inlet side profile and a pulp suspension receiving side profile facing away from the inlet side profile. . 6. The method of claim 5, wherein step (b) comprises forming a plurality of first grooves in a top surface of the plate material. 7. The method of claim 6, wherein step (c) comprises forming a plurality of second grooves in a bottom surface of the plate material. 8. The method of claim 7, wherein step (d) cuts the slots to connect each one of the top grooves to each one of the bottom grooves. 9. The method of claim 8, wherein step (d) is performed subsequent to step (e). 10. The method of claim 9, wherein said cutting comprises laser cutting. 11. The method according to claim 9, wherein said cutting comprises a water jet cutting. 12. The method according to claim 9, comprising curing the cylindrical shape before step (e) and after step (d). 13. The step (d) includes cutting the slot to connect each one of the top grooves to a respective one of the bottom grooves while the solid plate material is solid. The method of claim 7, leaving a plurality of solid uncut bridge members extending between the regions. 14. The step (b) forms the pulp suspension inlet side contour along the entire length, and the step (c) forms the pulp suspension receiving side contour to the length. 14. The method of claim 13, comprising forming along the entire direction. 15. The method of claim 13, wherein step (b) comprises forming the slots along the entire length. 16. Supplying a plate material having a first surface, a second surface, a length direction, a width direction, and a predetermined thickness, along substantially the full length of the plate to define an inlet pattern. Forming a first series of longitudinally extending grooves in the first surface; a second series of longitudinally extending along the substantially full length of the plate on the second surface to define an exit pattern. Forming an extending groove, provided that the first groove and the second groove of the first surface and the second surface are overlapped with each other and are fixedly arranged, and do not cut through the thickness of the plate; Forming a cylindrical body, securing a support ring around the cylindrical body, and extending longitudinally through the first and second series of grooves superimposed along substantially the entire length of the plate. Cutting the Tsu bets, the between the first and second series of grooves consists of communicating, the method of the papermaking material to form a screen cylinder for sieving. 17. The method of claim 16, wherein cutting the slot comprises leaving a plurality of solid uncut bridge members extending between solid regions of the plate material. 18. The step of forming the plate into the cylinder comprises cutting the plate to a desired length, rolling or bending the plate, and butting the longitudinally extending ends of the plate. 17. The method of claim 16, comprising forming a defined seam. 19. The method of claim 16, wherein cutting the longitudinally extending slot comprises laser cutting. 20. The method of claim 16, wherein cutting the longitudinally extending slot comprises E-beam cutting. 21. The method of claim 16, wherein the step of cutting a longitudinally extending slot comprises electro-discharge machining. 22. The method of claim 16, wherein cutting the longitudinally extending slot comprises water jet cutting. 23. The slot is cut after the cylinder is formed.
The method of claim 16. 24. The method of claim 16, comprising forming the first series of longitudinal extensions along the entire length. 25. The method of claim 24, comprising forming the second series of longitudinal extensions along the entire length. 26. The method of claim 24, comprising cutting the longitudinal slot along the entire length. 27. A plate material formed in a cylindrical body, said cylindrical body having an inlet surface on a first side and an outlet surface on a second side, extending axially along said cylindrical body, and A substantially parallel spaced groove of a first pattern disposed on either the first or second cylindrical body and extending substantially along the entire length of the cylindrical body extending in the axial direction, formed on the other side of the cylindrical body; A series of slots each extending substantially along the entire axial length of the cylinder, wherein each one of the grooves communicates with a respective one of the slots, and A screen cylinder for sieving the papermaking raw material, the screen cylinder being in communication with the outlet surface. 28. The apparatus of claim 2, further comprising at least one bridge member in one of said slots connecting solid regions of said plate material on opposite sides of said slot.
8. The screen cylinder according to 7. 29. Each of the slots comprises a plurality of bridge members.
A screen cylinder according to claim 1. 30. The screen cylinder of claim 27, wherein the substantially parallel spaced grooves of the first pattern extend along the entire axial length of the cylinder. 31. The screen cylinder according to claim 27, wherein said series of slots extend along said axially extending length of said cylinder. 32. A plate material formed in a cylindrical body having a central axis,
The cylindrical body has an inlet surface on a first cylindrical body side and an outlet surface on a second side, and is formed in an axial direction along the inlet surface and extends substantially along the entire axial length of the inlet surface. A first groove substantially parallel to and spaced from the first groove, and a second pattern of substantially parallel second grooves substantially coinciding with the first groove and formed in the axial direction along the full length exit surface; A series of axially extending slots formed in the cylinder and extending substantially along the entire axial length of the cylinder, wherein the slots substantially match respective ones of the first grooves with the first grooves. A screen cylinder for sieving paper stock, connected to a respective one of said second grooves. 33. The screen cylinder of claim 32, wherein said slots extend axially and are disposed substantially parallel to one another about said cylinder. 34. The slot of claim 3, wherein said slot is a laser cut slot.
4. The screen cylinder according to 3. 35. The screen cylinder according to claim 33, wherein said slot is a water jet cut slot. 36. The screen cylinder of claim 33, wherein said slot is an electro-discharge machined slot. 37. The screen cylinder according to claim 32, wherein the substantially parallel groove of the first pattern extends along the entire axial length of the cylindrical body. 38. The screen cylinder according to claim 32, wherein the substantially parallel groove of the second pattern extends along the entire axial length of the cylindrical body. 39. The screen cylinder of claim 32, wherein said axially extending slot extends along an entire axial length of said cylinder. 40. A plate material formed on a cylindrical body, wherein the cylindrical body comprises a first material.
The cylindrical body has an inlet surface, a central axis, and an outlet surface formed on a second cylindrical body, the second cylindrical body being defined by a pattern of first grooves extending axially but not penetrating the plate, One groove extends substantially along the entire axial length of the cylinder, and the cylinder has a series of axially extending slots formed along the inlet surface and communicating with the axially extending groove on the second cylinder side. For sieving a papermaking stock suspension, wherein the slot extends substantially along the entire axial length of the cylinder, and the groove and slot permit filtration flow through the slot which together function as a filtration medium. Screen cylinder. 41. The screen cylinder according to claim 40, wherein said first groove extends along the entire axial length of said cylindrical body. 42. The screen cylinder of claim 40, wherein said axially extending slot extends along an entire axial length of said cylinder.