Grinding plate for a refiner and refiner comprising such a grinding plate

Abstract

The invention relates to a grinding plate for a refiner, the grinding plate (10) comprising a plurality of refiner blades (14) separated by grooves (15), further comprising a plurality of refiner slats (16) arranged across the grooves (15) to connect the refiner blades (14) on either side of the grooves (15) to each other, and further comprising at least one through hole (18) in at least one refiner slat (16) for enabling flow through the slat (16) along the groove (15). The invention further relates to a refiner comprising such a grinding plate (10) and to a method for manufacturing the grinding plate (10).

Description

Technical Field

[0001] The present invention relates to a grinding disc for a fine grinding mill to finely grind lignocellulosic materials, wherein the grinding disc includes a plurality of fine grinding mill teeth separated by grooves and a plurality of fine grinding mill baffles arranged across the grooves to connect the fine grinding mill teeth on either side of the grooves to each other. Background Technology

[0002] Disc mills are commonly used in the pulp industry to refine fibrous materials, such as lignocellulosic materials used in paper and paperboard production.

[0003] A disc grinding mill comprises two or more opposing grinding elements, at least one of which is rotatable. The rotating grinding element may be referred to as a rotor or rotor-side grinding disc, while the non-rotating or stationary grinding element may be referred to as a stator or stator-side grinding disc. A grinding gap exists between the grinding elements, at which the material to be ground is abraded against the grinding surface and ground. The grinding surface of the grinding element includes multiple cutting teeth separated by grooves, used to grind lignocellulosic materials during use.

[0004] In some applications, the rotor-side grinding discs and stator-side grinding discs are circular discs mounted on a stationary frame element and a rotating frame element in a finishing mill, thus facing each other during use. Typically, the stator-side and rotor-side grinding discs are divided into multiple smaller disc segments, each covering a sector of the frame element, and when assembled together, form a circular disc. An opening is usually provided at the center of at least one circular disc for feeding lignocellulosic material, allowing the material to enter at the center and be conveyed radially during finishing.

[0005] While the grinding mill blades are used to grind lignocellulosic materials, the grinding mill slurry baffles lift the material upwards from the grooves towards the grinding gap, ensuring thorough and uniform grinding. Due to the high pressure and temperature between the grinding discs, moisture present in the lignocellulosic material forms steam. However, the presence of steam can hinder the lignocellulosic material from moving across the grinding discs, especially near the pressure peaks in the grinding gap between the inner and outer edges of the discs. The extremely high pressure at these peaks often causes steam to flow back towards the inner edge, preventing the lignocellulosic material from flowing effectively across these pressure peaks. This reduces grinding efficiency, leading to higher costs and excessive wear on the grinding discs, thus shortening their lifespan and requiring frequent maintenance. Furthermore, localized pressure maxima can also occur, causing excessive wear or damage to the grinding discs.

[0006] There are currently no effective solutions to alleviate these problems. Summary of the Invention

[0007] The object of this invention is to eliminate or at least minimize the problems discussed above. This is achieved by the grinding discs for a fine grinding mill, the fine grinding mill, and the method for manufacturing the grinding discs, according to the appended independent claims.

[0008] The grinding disc of the present invention includes a plurality of grinding mill teeth separated by grooves, and also includes a plurality of grinding mill baffles arranged across the grooves to connect the grinding mill teeth on either side of the grooves to each other. Furthermore, the grinding disc includes at least one through-hole located in at least one grinding mill baffle for allowing flow through the baffle along the grooves.

[0009] By providing a through-hole for at least one slurry baffle, the grinding disc of the present invention allows the flow of lignocellulosic material to be lifted into the grinding mill gap by the slurry baffle during operation within a fine grinding mill, while allowing steam to flow through the through-hole and thus through the slurry baffle without interrupting the flow of lignocellulosic material. This is highly advantageous for improving the operation of the fine grinding mill, achieving efficient fine grinding, while limiting energy consumption and extending the service life of the grinding disc.

[0010] Suitable for use, the through-hole has a width that differs from the groove width by less than 10%. Thus, the width of the through-hole is close to the width of the groove itself, allowing a large amount of steam to flow through it.

[0011] Alternatively, the through-hole has a width less than 80%, preferably less than 60%, and more preferably less than 40% of the groove width. This results in a narrower through-hole, making the slurry baffle itself more robust and stable, while still allowing steam to flow through it.

[0012] The through-hole appropriately has a lower end, the height of which from the bottom of the groove is less than 50%, preferably less than 20%, and more preferably less than 10% of the height of the slurry baffle. Thus, the through-hole is positioned close to the bottom of the groove, which facilitates the smooth flow of steam that is separated from the lignocellulosic material flow raised into the gap of the fine grinding mill.

[0013] Furthermore, the through-hole appropriately has a height less than half, preferably less than one-third, of the height of the slurry baffle in the grinding mill. This ensures the stability of the grinding mill slurry baffle and allows for improved flow of lignocellulosic material without undue damage or breakage.

[0014] The through-hole also suitably has a height that is at least one-quarter of the height of the slurry baffle in the fine grinding mill. Thus, the through-hole becomes large enough to allow for the reliable and efficient flow of large volumes of steam.

[0015] Appropriately, multiple grinding mill slurry baffles include through-holes. This improves the flow of steam across the grinding plates. In some embodiments, at least 50% of the grinding mill slurry baffles include at least one through-hole. Consequently, the overall steam flow across the grinding plates is further improved.

[0016] Furthermore, multiple grinding mill baffles can be suitably arranged along a groove and include through-holes aligned to create channels along the groove. This improves steam flow because the through-holes prevent steam from being lifted into the grinding mill gap, allowing steam to flow along the groove, while the lignocellulosic material is regularly lifted into the grinding mill gap whenever it encounters a grinding mill baffle.

[0017] Appropriately, at least one fine grinding mill baffle at the outer periphery of the grinding disc is solid and without through holes. Thus, as steam and lignocellulosic material approach the outer periphery, both are lifted by this fine grinding mill baffle. This is advantageous for improving the discharge of material from the grinding disc after fine grinding.

[0018] In some embodiments, each slurry baffle adjacent to the outer periphery of the grinding disc is solid and without through holes. This achieves the advantages disclosed above throughout the entire circumference of the grinding disc.

[0019] Suitable, at least one grinding mill slurry baffle extends downward into the groove at an angle to the flow direction along the groove, said angle being less than 90°, preferably less than 60°, and more preferably less than 45°. This allows steam to be guided into the through-hole to improve flow through it.

[0020] At least one grinding mill slurry baffle has a height less than 80%, preferably less than 65%, of the grinding mill cutter tooth height. Thus, for half-height slurry baffles or sub-surface slurry baffles, the advantage of having through holes in the grinding mill slurry baffle is also achieved.

[0021] Appropriately, the grinding disc includes a peak region located between its inner and outer peripheries, and each through-hole in the grinding mill's slurry baffle is arranged between the peak region and the inner periphery. This allows steam to flow through the through-holes between the inner periphery and the peak region, thus enabling steam backflow that would normally occur when pressure increases. This further reduces energy consumption and improves grinding because the lignocellulosic material is guided towards the peak region more efficiently compared to existing technologies.

[0022] Furthermore, all the grinding mill slurry baffles on the grinding disc appropriately include at least one through hole. This further improves the flow of steam on the grinding disc.

[0023] Appropriately, all the grooves are interconnected. This is achieved through through-holes distributed in multiple grinding mill slurry baffles, and provides the advantage of more evenly distributing pressure across the grinding discs.

[0024] The grinding disc can be a portion of the disc with a center angle of 10° to 360°.

[0025] The present invention also relates to a fine grinding mill for fine grinding of lignocellulosic materials, wherein the fine grinding mill includes at least one grinding disc according to the present invention.

[0026] Suitablely, the grinding discs according to the invention are arranged as rotor-side grinding discs in a fine grinding mill. This makes the flow of steam across the grinding discs particularly advantageous during use, since steam typically flows to a greater extent in the grooves of rotating grinding discs than in stationary grinding discs.

[0027] The present invention also relates to a method for manufacturing the grinding disc of the present invention. The method includes the following steps: Provide the production data for this grinding wheel. This production data is supplied to the 3D printer, and A 3D printed model of the grinding disc.

[0028] This enables the manufacture of grinding discs with through-holes in at least one fine grinding mill slurry via additive manufacturing (3D printing). This allows for the precise measurement and placement of the through-holes, thereby realizing the advantages of the invention in a particularly advantageous manner.

[0029] After reading the following detailed description, those skilled in the art will readily understand the many additional benefits and advantages of the present invention. Attached Figure Description

[0030] The invention will now be described in more detail with reference to the accompanying drawings, in which: Figure 1 A top plan view of a portion of a grinding disc according to a first embodiment of the present invention is disclosed; Figure 2 Publicly disclosed from Figure 1 A three-dimensional view of the inner periphery of the grinding disc; Figure 3 Publicly disclosed from Figure 1 A three-dimensional view of the grinding disc from the side; Figure 4 Publicly disclosed from Figure 1 A plan view of the inner periphery of the grinding disc; Figure 5a A side plan view of a fine grinding mill slurry baffle with through holes according to the present invention is disclosed; Figure 5b A side plan view of another design of a fine grinding mill slurry baffle with through holes according to the present invention is disclosed; Figure 5c A side plan view of yet another design of a fine grinding mill slurry baffle with through holes according to the present invention is disclosed; Figure 6aA side plan view of the slurry baffle of the grinding disc according to the first embodiment is disclosed; Figure 6b A side plan view of the slurry baffle of the grinding disc according to the second embodiment is disclosed; Figure 6c A side plan view of the slurry baffle of the grinding disc according to the third embodiment is disclosed; Figure 6d A side plan view of the slurry baffle of the grinding disc according to the fourth embodiment is disclosed; and Figure 7 The steps of the method according to the present invention are schematically disclosed.

[0031] All accompanying drawings are schematic and not necessarily drawn to scale, and generally only show the parts necessary to illustrate the various embodiments, while other parts may be omitted or only implied. Unless otherwise stated, any reference numerals appearing in multiple drawings refer to the same object or feature in all drawings. Detailed Implementation

[0032] Figure 1 A portion of a grinding disc 10 for a fine grinding mill according to a first embodiment of the present invention is disclosed. The grinding disc 10 includes an inner peripheral edge 11 and an outer peripheral edge 12, and a fine grinding surface 13 is arranged therebetween. This fine grinding surface 13 includes a plurality of fine grinding mill teeth 14 for fine grinding lignocellulosic materials. The fine grinding mill teeth 14 are separated by grooves 15 and connected by a fine grinding mill baffle 16, which can be configured as follows: Figure 1 The diagram shows only two adjacent grinding mill teeth 14 connected, or alternatively, multiple grinding mill teeth 14 can extend across multiple grooves 15 to connect. Reference will be made below. Figure 2 As explained below, at least one fine grinding mill baffle 16 of the grinding disc 10 includes a through hole 18. As is well known in the art, the fine grinding mill teeth 14 are used for fine grinding of lignocellulosic material, while the fine grinding mill baffle 16 is used to ensure that the lignocellulosic material conveyed in the groove 15 is lifted toward the fine grinding surface 13 at the upper end 20 of the fine grinding mill teeth 14, thereby enabling fine grinding. When the grinding disc 10 is mounted in the fine grinding mill, the fine grinding surface 13 at the upper end 20 of the fine grinding mill teeth 14 generally defines the fine grinding mill gap together with the fine grinding surfaces on the opposite grinding disc.

[0033] The through-hole 18 is defined as an opening extending through the grinding mill baffle 16, thereby establishing a connection between a groove 15 on one side of the grinding mill baffle 16 and a groove 15 on the opposite side of the grinding mill baffle 16. The through-hole 18 is defined by the material of the grinding mill baffle 16, and in some embodiments also by the material of the grinding mill teeth 14 connected through the grinding mill baffle 16, and the bottom 19 of the groove 15. This will be referred to Figures 5a to 5cThis will be explained in more detail below. It is particularly important to note that the through hole 18 is defined by material around its entire periphery; that is, the through hole 18 is not in the form of a notch, groove, or recess.

[0034] During operation in the grinding mill, the grinding discs 10 are arranged as either stator-side or rotor-side grinding discs. The lignocellulosic material is fed into the grinding mill and reaches the grinding discs 10 at the inner periphery 11. It then moves across the grinding discs 10 toward the outer periphery 12 and is ground by contacting the grinding mill teeth 14 in the grinding mill gap between the grinding surfaces 13 formed on the rotor-side grinding discs and the stator-side grinding discs. The design and arrangement of the grinding mill teeth 14 and the grinding mill baffles 16 can vary in different sections of the grinding discs 10.

[0035] When it is stated herein that lignocellulosic material is lifted into the gap of a fine grinding mill, or that fine grinding occurs in the gap of a fine grinding mill, this should be understood as the space defined by the upper end 20 of the fine grinding mill tooth 14 on one grinding disc 10 and extending to the upper end of the fine grinding mill tooth on the opposite grinding disc, which may be a grinding disc according to the invention or another type of fine grinding mill grinding disc.

[0036] As used in this article, the term "lignocellulosic material" refers to a material containing lignin, cellulose, and hemicellulose. One example of such a material is wood, and other examples include other agricultural or forestry waste.

[0037] In the following text, when it is mentioned that a feature or dimension of grinding disc 10 (e.g., the height or width of a feature) is the same as another “basically”, this should be understood as being the same within manufacturing tolerances, or at least differing by no more than 10%.

[0038] The pressure in the grinding gap between the grinding discs varies as the lignocellulosic material flows from the inner periphery 11 to the outer periphery 12, with a pressure peak in peak region 17 where the pressure is at its maximum, and then abruptly decreases outside peak region 17, i.e., between peak region 17 and outer periphery 12. Peak region 17 is defined as the region extending circumferentially along the grinding disc 10 and having a higher pressure than any other part of the grinding disc 10. Inside peak region 17, i.e., between peak region 17 and inner periphery 11, vapor tends to flow against the flow of lignocellulosic material, thus moving towards the inner periphery. Outside peak region 17, i.e., between peak region 17 and outer periphery 12, vapor flows instead along the flow of lignocellulosic material.

[0039] Figure 2The grinding disc 10 is shown in a perspective view, illustrating through-holes 18 in a plurality of grinding mill baffles 16. In this embodiment, the through-holes 18 are located at the lower end 21 of the grinding mill baffles 16 and extend to the bottom 19 of the groove 15 in which the grinding mill baffles 16 are arranged. The through-holes 18 allow flow along the groove 15 through the grinding mill baffles 16 and are particularly suitable for the flow of steam generated in the grinding mill due to the increased pressure between the grinding mill discs. Thus, steam can flow along the groove 15, while the lignocellulose material is lifted by the grinding mill baffles 16 to the upper end 20 of the grinding mill teeth 14, i.e., to the grinding surface 13, thereby ensuring that the flow of steam does not impede the flow of lignocellulose material, and that the lignocellulose material itself is carried into the grinding mill gap for grinding. Due to the high pressure in the peak region 17, which forces the steam to flow away from the peak region 17, the steam generally flows toward the inner periphery 11, while the lignocellulose material flows across the peak region 17 toward the outer periphery 12. The lignocellulosic material is able to move across the peak region 17 due to the fact that continuously feeding the lignocellulosic material into the mill prevents backflow.

[0040] Figure 3 The grinding disc 10 is disclosed in a perspective view, showing a groove 15 with three grinding mill baffles 16 arranged to connect grinding mill teeth 14 to adjacent grinding mill teeth 14 (not shown). Each grinding mill baffle 16 has a through-hole 18 to form a channel C along the groove 15, allowing steam to flow unimpeded along the length of the groove 15. This is particularly advantageous in separating steam from the lignocellulosic material, thus ensuring that grinding in the grinding mill gap becomes particularly efficient.

[0041] In some embodiments, only one fine grinding mill slurry baffle 16 on the grinding disc 1 includes a through hole 18, but in the first embodiment, multiple fine grinding mill slurry baffles 16 each include such a through hole 18. In fact, in the first embodiment, at least 50% of the fine grinding mill slurry baffles include a through hole 18.

[0042] In some embodiments, all the through-holes 18 in the grinding mill baffle 16 are arranged between the peak region 17 and the inner periphery 11 to ensure that the steam flow toward the inner periphery 11 does not interfere with the flow of lignocellulosic material toward the peak region 17. The grinding mill baffle 16 between the peak region 17 and the outer periphery 12 is instead solid and without through-holes 18 to ensure maximum strength of the grinding mill baffle 16. Because the steam and lignocellulosic material flow in the same direction, i.e., toward the outer periphery 12, after passing through the peak region 17, the steam does not impede the grinding efficiency in the grinding mill gap.

[0043] Advantageously, at least one polishing slurry baffle 16 without through holes 18 is provided near the outer periphery 12, i.e., it is configured as a solid polishing slurry baffle 16. In this way, both steam and lignocellulosic material are lifted by the polishing slurry baffle 16 to the outer periphery 12 and discharged together from the grinding disc 1. In the first embodiment, each polishing slurry baffle 16 adjacent to the outer periphery 12 is solid and without through holes 18. This means that for a circular grinding disc, the polishing slurry baffles 16 distributed at the outer periphery 12 in the circumferential direction surrounding the grinding disc 10 are solid.

[0044] Figure 4 A plan view of the grinding disc 10, showing the through-hole 18 more clearly, viewed from the inner periphery outwards, is disclosed. In a first embodiment, the through-hole 18 is located at the bottom 19 of the groove 15, while the polishing mill baffle 16 then extends upwards to the upper end 20 of the polishing mill teeth 14. Therefore, the polishing mill baffle 16 has a baffle height dh that is substantially the same as the tooth height bh (within manufacturing tolerances, or at least differing by no more than 10%). This means that when the grinding disc 10 is used in a polishing mill, the polishing mill baffle 16 is able to lift the lignocellulosic material all the way up to the polishing mill gap, i.e., up to the upper end 20 of the polishing mill teeth 14.

[0045] In some embodiments, at least one, and preferably at least some, mill dams 16 are alternatively subsurface dams, i.e., mill dams 16 having a dam height dh that is lower than the tooth height bh. The dam height dh of such a subsurface dam is less than 80% of the tooth height bh, preferably less than 65% of the tooth height. This means that these subsurface dams can lift the lignocellulosic material toward the upper end 20 of the mill dam teeth 14, but they do not extend all the way to the upper end 20 themselves.

[0046] In the first embodiment, the through-hole 18 has a width w, which is substantially the same as, or at least no more than 10% different from, the groove width gw of the groove 15 in which the through-hole 18 is disposed (i.e., the groove in which the grinding mill baffle 16 including the through-hole 18 is disposed). Typically, the grinding mill teeth 14 are wider at the bottom 19 of the adjacent groove 15 and taper towards the upper end 20, meaning that the groove width gw is smaller at the bottom 19 and increases towards the upper end 20 of the grinding mill teeth 14. Therefore, when it is stated that the width w of the through-hole 18 is the same as the groove width gw, it means that at any given height from the bottom 19 of the groove, the width of the through-hole 18 is the same as the groove width gw at that height.

[0047] Figure 5aA fine grinding mill slurry baffle 16 with a through hole 18, according to a first embodiment, is disclosed, having a width w the same as the groove width gw. The through hole 18 has a height h, which is less than half of the slurry baffle height dh, preferably less than one-third of the slurry baffle height dh, and extends to the bottom 19 of the groove 15.

[0048] Figure 5b A polishing mill slurry baffle 16 is disclosed in which the width w of the through-hole 18 is smaller than the groove width gw. In this embodiment, the through-hole has a width that is less than 80%, preferably less than 60%, and more preferably less than 40% of the groove width gw. This makes the polishing mill slurry baffle 16 more stable and improves its ability to withstand the flow of steam and lignocellulose material without breaking.

[0049] In this embodiment, the height h of the through-hole 18 is less than one-third of the height dh of the slurry baffle. In this embodiment, the through-hole 18 does not extend to the bottom 19 of the groove 15, but instead has a lower end 21 whose height H from the bottom 19 of the groove 15 is less than 50%, preferably less than 20%, and more preferably less than 10% of the slurry baffle height dh. Although steam flow is most efficient when it is allowed to pass unobstructed through the bottom 19 of the groove 15, it is sometimes desirable to arrange the through-hole 18 higher than it is on the slurry baffle 16 of the polishing mill, particularly to prevent the through-hole 18 from becoming clogged due to the fibers of the lignocellulosic material.

[0050] Figure 5c Another design is disclosed, which combines the width w of the through-hole 18 of the first embodiment with a through-hole located at a height H from the bottom 19 of the trench 15. Advantageously for all embodiments described herein, the height h of the through-hole 18 is greater than one-quarter of the baffle height dh, as this enables a high steam flow rate. Meanwhile, some embodiments may have a smaller height h, where only a smaller steam flow rate is required.

[0051] It should be noted that, in addition to the differences explicitly pointed out above, Figures 5a to 5c The implementation methods are similar or identical in all respects.

[0052] It should also be noted that the grinding disc 10 according to any embodiment disclosed herein may include a plurality of through holes 18 that are different from each other, such that some through holes 18 can conform to Figure 5b The embodiment shown, while other through holes 18 conform to Figure 5c and / or Figure 5aThe implementation methods are as follows. Similarly, in some implementations, the size of the through-hole 18 can be freely varied from one type of through-hole 18 to another, thus allowing the use of multiple different designs on the same grinding disc 10. In other implementations, all through-holes 18 can have the same size, thus allowing only one design or implementation to be represented on the grinding disc 10.

[0053] Figure 6a A first embodiment of the grinding mill slurry baffle 16 is shown from the side, wherein a through-hole 18 is provided at the bottom 19 of the groove 15, and arrow S indicates the steam flow direction of the grinding disc 10 during use. The grinding mill slurry baffle 16 according to this design is provided with an outer baffle surface 22, which is substantially perpendicular to the radial direction from the inner periphery 11 to the outer periphery 12. The grinding mill slurry baffle 16 also has an inner baffle surface 23, which is angled relative to the radial direction to form an upward slope, thereby effectively lifting the lignocellulosic material along the inner baffle surface 23. Arrow M indicates the flow direction of the lignocellulosic material upon reaching the grinding mill slurry baffle 16.

[0054] Figure 6b A second embodiment is shown, in which the inner baffle surface 23 maintains an upward slope, but the outer baffle surface 22 shows a downward slope, thereby guiding steam into the through-hole 18. This can be represented as the mill baffle 16 extending downward into the groove 15 at an angle α with respect to the flow direction along the groove, wherein this angle α is less than 90°. Figure 6b In the design, the angle α is less than 60°, and preferably less than 45°, to further improve the guidance of steam S into the through hole 18.

[0055] Figure 6c A third embodiment is shown, wherein the inner slurry baffle end 23 has an upward slope, while the outer slurry baffle end 22 has a downward slope, but the angle α is less than 90° but not less than 60°. Compared to Figure 6b The design provides guidance for steam to enter the through-hole 18 to a lesser extent, but at the same time ensures greater stability of the mill slurry baffle 16.

[0056] Figure 6d A fourth embodiment is shown, wherein the inner slurry baffle end 23 has an upward slope, while the outer slurry baffle end 22 is inclined away from the through hole 18. The polishing mill slurry baffle 16 of this design is a sub-surface slurry baffle, so that the polishing mill slurry baffle 16 does not reach the upper end 20 of the polishing mill cutter teeth 14.

[0057] It should be noted that, in addition to the differences explicitly pointed out above, Figures 6a to 6d The implementation methods are similar or identical in all other respects. Additionally, the grinding disc 10 may include only those based on… Figures 6a to 6dOne or more embodiments of the slurry baffles, so that any number of designs of the fine grinding mill slurry baffles 16 can appear on the grinding discs 10.

[0058] In some embodiments, all the grinding mill baffles 16 of the grinding disc 10 include at least one through hole 18. This improves the flow of steam on the grinding disc during use and also distributes the pressure more evenly on the grinding disc.

[0059] In some embodiments, all grooves 15 are interconnected. This is achieved by through-holes 18, but it can also be achieved by grinding mill teeth 14 designed not to extend uninterruptedly from the inner periphery 11 to the outer periphery 12. Therefore, the grinding mill teeth 14 can be arranged to be shorter than the distance from the inner periphery 11 to the outer periphery 12, or alternatively, can be arranged with interruptions, thereby enabling the connection of the grooves 15 on either side of the grinding mill teeth 14. By connecting the grooves 15 to each other in this way, the pressure distribution on the grinding disc is improved, thereby avoiding or at least minimizing localized pressure maxima.

[0060] In the above-described embodiments, it is particularly advantageous to provide through holes 18 in the slurry baffle 16 of the fine grinder to promote the flow of steam, as this reduces the risk of local pressure maxima and improves fine grinding by ensuring that the lignocellulosic material can flow smoothly and efficiently toward the peak region 17.

[0061] The grinding disc 10 of the present invention is a circular grinding disc, but it can also be configured as a grinding disc portion having a central angle of less than 360°, most preferably in the range of 10° to 360°, the upper end of which is the circular grinding disc 10. When the grinding disc 10 is configured as a grinding disc portion having a smaller central angle (commonly referred to as a segment), multiple grinding disc portions are provided to form a circular grinding disc when mounted in a fine grinding mill.

[0062] When using the grinding disc 10 in a fine grinding mill, it is particularly advantageous to arrange the grinding disc 10 of the present invention as a rotor-side grinding disc, because it has been found that steam is mainly transported along the rotor-side grinding disc. However, the grinding disc 10 can also be arranged as a stator-side grinding disc, thereby achieving a more efficient flow of steam along the stator-side grinding disc.

[0063] Now refer to Figure 7 A method for manufacturing grinding discs according to the present invention is described.

[0064] The method includes providing production data for the grinding disc 10 according to any embodiment disclosed herein.

[0065] Typically, in this disclosure, production data can be provided in any suitable data type. Generally, 3D printable models can be created using computer-aided design (CAD) software, via a 3D scanner, or by a common digital camera and photogrammetry software. 3D printing models created with CAD result in fewer errors and can be corrected before printing, allowing for verification of the design before the object is printed. Therefore, CAD data is preferred in this disclosure.

[0066] In one specific embodiment of this disclosure, a 3D model of a grinding mill segment is produced using a CAD package, wherein the 3D model of the grinding mill segment created by the CAD program is a mathematical representation stored in a first data file having a suitable file format, such as an STL file. Suitable CAD packages include, for example, Pro / Engineer and SolidWorks. Optionally, but preferably, the data in the first and second data files is checked for errors and defects using a suitable software package, such as one provided by EOS Electronic Manufacturing Solutions. In addition to correcting errors in the data files, it is important that all geometry in the grinding mill segment model is reproducible and applicable to subsequent manufacturing steps. Depending on the geometry incorporated into the grinding mill segment and the specific 3D printer and 3D printer software selected, the data contained in the data file is mathematically sliced ​​into layers, which may have a virtual thickness of, for example, 0.01 mm.

[0067] The method also includes feeding production data to the 3D printer.

[0068] Typically, in this disclosure, the printing step can be performed by any suitable type of 3D printer. Preferred printing materials are selected from metals or metal alloys. However, the invention is not limited to specific printing materials.

[0069] The method also includes 3D printing a model of the 103 grinding disc 10.

[0070] Therefore, the mathematically sliced ​​data file is input into a suitable 3D printer software package, and the 3D printer is used to print the polishing disc. Different 3D printing technologies can be used, but the preferred technology is the so-called Direct Metal Laser Sintering (DMLS), which utilizes a ytterbium (Yb) fiber laser emitted into a bed of metal powder.

[0071] It should be noted that, unless explicitly stated that such a combination is inappropriate, the features of the various implementation methods described herein can be freely combined.

Claims

1. A grinding disc for a fine grinding mill, the grinding disc (10) comprising a plurality of fine grinding mill teeth (14) separated by grooves (15), and further comprising a plurality of fine grinding mill baffles (16) arranged across the grooves (15) to connect the fine grinding mill teeth (14) on either side of the grooves (15) to each other, and further comprising at least one through hole (18) in at least one of the fine grinding mill baffles (16) for allowing steam to flow through the baffles (16) along the grooves (15).

2. The grinding disc according to claim 1, characterized in that, The through hole (18) has a width that differs from the width of the groove (15) by no more than 10%.

3. The grinding disc according to claim 1, characterized in that, The through hole (18) has a width (w) that is less than 80%, preferably less than 60%, and more preferably less than 40% of the width (gw) of the groove (15).

4. The grinding disc according to any one of the preceding claims, characterized in that, The through hole (18) has a lower end (21), the height (H) of the lower end from the bottom of the groove (15) is less than 50% of the slurry baffle height (dh), preferably less than 20% and more preferably less than 10%.

5. The grinding disc according to any one of the preceding claims, characterized in that, The through hole (18) has a through hole height (h) that is less than half the height (dh) of the slurry baffle (16) of the fine grinding mill, preferably less than one-third of the height (dh) of the slurry baffle.

6. The grinding disc according to any one of the preceding claims, characterized in that, The through hole (18) has a through hole height (h) that is at least one-quarter of the height (dh) of the slurry baffle (16) of the fine grinding mill.

7. The grinding disc according to any one of the preceding claims, characterized in that, The plurality of the aforementioned fine grinding mill slurry baffles (16) include through holes (18).

8. The grinding disc according to claim 7, characterized in that, At least 50% of the polishing mill slurry baffles (16) include at least one through hole (18).

9. The grinding disc according to claim 7 or 8, characterized in that, Multiple grinding mill baffles (16) are arranged along a groove (15) and include through holes (18) aligned to create channels along the groove (15).

10. The grinding disc according to any one of the preceding claims, characterized in that, At least one fine grinding mill slurry baffle (16) at the outer periphery (12) of the grinding disc is solid and has no through hole (18).

11. The grinding disc according to claim 10, characterized in that, Each fine grinding mill baffle (16) adjacent to the outer periphery (12) of the grinding disc is solid and has no through holes (18).

12. The grinding disc according to any one of the preceding claims, characterized in that, At least one of the grinding mill baffles (16) extends downward into the groove (15) such that the outer baffle surface (22) forms an angle with the steam flow direction along the groove, the angle being less than 90°, preferably less than 60°, and more preferably less than 45°.

13. The grinding disc according to any one of the preceding claims, characterized in that, At least one grinding mill slurry baffle (16) has a slurry baffle height (dh) that is less than 80% of the grinding mill cutter tooth height.

14. The grinding disc according to any one of the preceding claims, characterized in that, It also includes a peak region (17) located between the inner periphery (11) and the outer periphery (12) of the grinding disc (10), and wherein each of the through holes (18) in the fine grinding mill baffle (16) is arranged between the peak region (17) and the inner periphery (11).

15. The grinding disc according to any one of claims 1 to 9 or 12 to 14, characterized in that, All polishing mill slurry baffles (16) include at least one through hole (18).

16. The grinding disc according to any one of the preceding claims, characterized in that, All the grooves (15) are connected to each other.

17. The grinding disc according to any one of the preceding claims, characterized in that, The grinding disc (10) is a portion of the grinding disc having a central angle of 10° to 360°.

18. A grinding mill for finely grinding lignocellulosic materials, said grinding mill comprising at least one grinding disc (10) according to any one of claims 1 to 17.

19. The fine grinding mill according to claim 16, characterized in that, The grinding disc (10) according to any one of claims 1 to 17 is arranged as a rotor-side grinding disc in the fine grinding mill.

20. A method for manufacturing a grinding disc according to any one of claims 1 to 17, comprising: Provide the production data of the grinding disc (10), The production data is supplied to the 3D printer, and A 3D printed model of the grinding disc.

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