diagonal net former
By arranging the outlet gap above the horizontal section in the inclined wire forming machine and combining it with dewatering elements and a steam blowing box, the problem of fiber material suspension backflow was solved, enabling the production of high-quality long-fiber paper webs and wet-laid nonwoven webs.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- VOITH PATENT GMBH
- Filing Date
- 2023-08-18
- Publication Date
- 2026-05-12
AI Technical Summary
When using existing inclined wire forming machines to manufacture long fiber paper webs or wet-laid nonwoven fabric webs, the fiber material suspension flows back in the inclined section of the wire, resulting in a decrease in quality and making it difficult to meet high-quality requirements such as small holes, uniform thickness, and surface quality.
The outlet gap of the headbox is arranged above the basically horizontal extension section of the net, and a dewatering element is set below it. The water line position is adjusted by a fixed suction device. Combined with the steam blowing box and the upper net, uniform deposition and rapid dewatering of the fiber material suspension are ensured.
It effectively prevents the backflow of fiber material suspension, improves the quality of fiber material webs, and achieves small holes, uniform thickness and surface quality, meeting the high-quality requirements for the production of battery separator paper and aramid paper webs.
Smart Images
Figure CN117604802B_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to an inclined wire forming device for manufacturing fibrous material webs, particularly long-fiber paper webs or wet-laid nonwoven webs, from a suspension of at least one fibrous material. The inclined wire forming device has a wire that travels over a peripheral region of a breast roll and subsequently extends at least partially in the direction of travel at an angle inclined relative to the horizontal before turning in a substantially horizontal direction at a turning point. In this inclined extension section of the wire, at least one headbox applies at least a portion of the suspension of at least one fibrous material to the wire on its upper side, and at least one dewatering element is arranged on its lower side for dewatering at least a portion of the suspension of at least one fibrous material applied to the wire. The headbox includes a front wall that, together with the wire, defines an outlet gap for the suspension of at least one fibrous material.
[0002] The present invention also relates to the use of such a slant wire forming apparatus for manufacturing long fiber paper webs or wet-laid nonwoven webs, especially battery separator paper webs or aramid paper webs or capacitor paper webs. Background Technology
[0003] Such a slanted mesh forming device is known, for example, from German publication DE 10 2004 047 518 A1, and is manufactured and sold by the applicant under the name "Hydroformer". It is primarily used for manufacturing long-fiber paper and wet-laid nonwoven fabrics, wherein fibers and fiber mixtures of different materials with lengths ranging from 1 mm to 40 mm are used in the forming of such sheets.
[0004] Some long-fiber paper webs or wet-laid nonwoven webs, such as battery separator paper webs, aramid paper webs, or capacitor paper webs, have very high quality requirements. Typically, they should have the lowest possible weight per unit area, without any so-called "pinholes," i.e., small pores. This assumes very good forming. Fiber agglomeration must be prevented, and the web should have the most uniform thickness and the most uniform lateral distribution of surface quality. In this case, there is still potential for further improvement in known oblique wire forming machines. Summary of the Invention
[0005] The objective of this invention is to improve the type of inclined wire forming machine described above, thereby enabling the achievement of high quality requirements for specific long fiber paper webs or wet-laid nonwoven webs, such as battery separator paper webs, aramid paper webs, or capacitor paper webs.
[0006] This task is accomplished by the oblique mesh forming device according to independent claim 1 and the application of such an oblique mesh forming device according to independent claim 10. Advantageous improvements of the invention are the subject of the dependent claims.
[0007] Specifically, the task is solved by a long net former, described at the beginning, which is categorized by type, wherein the front wall of the headbox extends beyond the turning part of the net in the direction of net travel, such that the outlet gap is arranged over a substantially horizontally extending section of the net.
[0008] The inventors recognized an advantage in that the quality of long-fiber paper webs or wet-laid nonwoven webs produced on conventional inclined wire forming machines is negatively affected by the fact that a portion of the fibrous material suspension escaping from the outlet gap flows back due to gravity in the inclined extension section of the web. This backflow can be reliably prevented by arranging the outlet gap over a substantially horizontally extending section of the web.
[0009] In the context of this invention, "a substantially horizontally extending section of the net" means that this section of the net either extends exactly horizontally or has a small angle relative to the horizontal line, i.e., less than 20°, preferably less than 10°, and more preferably less than 5°. In each case, the angle relative to the horizontal line of the "substantially horizontally extending section of the net" is smaller in absolute value than the angle relative to the horizontal line of an inclined section of the net.
[0010] Alternatively, the present invention can be described as a special combination of an inclined wire mesh forming device and a long wire mesh forming device, wherein the fiber material suspension is applied to the wire mesh in the region of the inclined wire mesh section and only a small portion of the wire mesh in the substantially horizontally extending wire mesh section by the special forming device.
[0011] Preferably, at least one dewatering element, arranged on the underside of the inclined extension section of the net, extends beyond the turning point of the net in the direction of net travel, thereby terminating below the substantially horizontally extending section of the net. In this way, it can be ensured that in all areas where the fibrous material suspension is applied to the net, dewatering also occurs through the net via at least one dewatering element.
[0012] Advantageously, the front wall of the headbox has an arch or bend in the area where the net turns, such that the distance between the front wall of the headbox and the net preferably decreases continuously in the direction of net travel. Because of this decreasing distance in the direction of net travel, the flow rate of the fibrous material suspension applied to the net can be kept approximately constant.
[0013] Advantageously, a fixed suction device is arranged below the substantially horizontally extending wire section, which allows the position of the waterline of at least one fiber material suspension to be defined on the substantially horizontally extending wire section. Immediately following the outlet gap, a large amount of fiber material suspension remains on the wire, allowing a high proportion of the material suspension to move further on the formed nonwoven fabric. The fibers still possess turbulent energy from the headbox and therefore may be deposited in the paper structure while still in motion. A side-view plan view toward the substantially horizontally extending wire section clearly shows the water content in the paper forming area and reveals a luminous specular reflective surface. This phenomenon is interrupted almost abruptly at the so-called "waterline," and subsequently, the surface appears relatively dull in the direction of wire travel. The position of the waterline can be adjusted using the fixed suction device.
[0014] Here, after the suction device is fixed, at least one additional dewatering element, particularly a suction box, can be arranged below the substantially horizontally extending web section, through which the fibrous material web can be further dewatered. The goal is to achieve a preset dry content of the fibrous material web before it is removed from the web.
[0015] To achieve the desired dryness as quickly and efficiently as possible, at least one steam blower can be arranged above a substantially horizontally extending web section. The viscosity of water in the fibrous material web can be reduced due to the steam, which is facilitated, for example, by a suction box arranged below the web for dehumidification of the fibrous material web.
[0016] Alternatively or additionally, for this purpose, at least one upper net may also be arranged above the substantially horizontally extending net section. This allows the fiber material web to be dewatered both downwards through the net and upwards through the upper net. This not only shortens the required dewatering path but also results in an improved surface finish of the fiber material web.
[0017] The web can have low air permeability (less than 410 CFM) and / or high retention value (greater than 100 FSI). Thus, fiber material webs can be reliably produced and transported at low stoffice levels.
[0018] To prevent the fibrous material suspension escaping from the outlet gap (which remains very flexible before reaching the waterline) from flowing laterally downward from the substantially horizontal net section, it is advantageous that the substantially horizontally extending sections of the net are at least laterally surrounded by edge limiters.
[0019] Another aspect of the invention relates to the use of the previously described oblique wire forming device according to the invention for manufacturing long-fiber paper webs or wet-laid nonwoven webs, particularly battery separator paper webs, aramid paper webs, or capacitor paper webs. The advantages of the oblique wire forming device according to the invention are particularly evident for these webs and their high quality requirements.
[0020] Here, it is preferable to operate the inclined mesh forming device according to the invention such that at least one water line of fibrous material suspension appears on the substantially horizontally extending mesh section. This thus avoids backflow of the fibrous material suspension.
[0021] The consistency of at least one fibrous material suspension can be less than 0.3%, preferably less than 0.02%. Low consistency is particularly advantageous for battery separator paper webs, aramid paper webs, or capacitor paper webs. Similarly, long-fiber paper webs or wet-laid nonwoven webs with a consistency of less than 20 g / m³ are also suitable. 2 Weight per unit area. Attached Figure Description
[0022] The invention will be further explained below with the aid of illustrative and non-to-scale drawings. Wherein:
[0023] Figure 1 The embodiments known from the prior art are shown, and
[0024] Figure 2 An embodiment according to the present invention is shown. Detailed Implementation
[0025] Figure 1 A schematic diagram illustrates an inclined wire forming machine 10' known from the prior art, which has a headbox 20' and a wire 30'. In normal operation, the wire 30', configured as a circulating wire loop, moves counterclockwise on a series of rollers. One of these rollers is configured as a breast roller 32'. In the wire travel direction, the wire 30' moves upward from the breast roller 32' at an angle inclined relative to the horizontal direction. In this inclined wire section, the headbox 20' applies a suspension of fibrous material onto the wire 30' on the upper side. To dewater the fibrous material suspension, a dewatering element 40' is arranged on the lower side in the inclined wire section.
[0026] The headbox 20' has a front wall 22' that, together with the net 30', defines an outlet gap 24' for the fiber material suspension. A fixed suction device 50' is located behind the dewatering element 40', by means of which the water level of the fiber material suspension can be adjusted. The outlet gap 24', the dewatering element 40', and the fixed suction device 50' are arranged here in an inclined region of the net 30'. The net 30' is then turned in a substantially horizontal direction by means of a first steering roller 34'. In the region between the first steering roller 34' and the second steering roller 36' in the direction of net travel (where the net 30' moves substantially horizontally), a further dewatering element 60' is arranged below the net 30' to further dewater the fiber material web.
[0027] Figure 2 An embodiment of the oblique mesh forming machine 10 according to the present invention is now schematically shown. Here, with Figure 1 Components shown that are similar to or identical to those described above are given the same reference numerals but without apostrophes. The differences between the two embodiments will then be discussed primarily, and reference will be made elsewhere to the above description. Figure 1 The implementation plan.
[0028] A key feature of the inclined wire mesh forming machine 10 according to the invention is that the outlet gap 24 is arranged over a substantially horizontally extending section of the wire mesh 30. For this purpose, the front wall 22 of the headbox 20 extends beyond the turning point, where the wire mesh 30 transitions from the inclined wire mesh section to the substantially horizontally extending wire mesh section. This reliably prevents the backflow of a portion of the fibrous material suspension escaping from the outlet gap onto the wire mesh 30, which would be detrimental to the quality of the fibrous material web to be manufactured. Here, the front wall 22 is curved in the region of the turning point such that its distance from the wire mesh 30 preferably decreases continuously in the wire mesh traveling direction.
[0029] The dewatering element 40, arranged below the net 30, also extends beyond the turning section until it reaches below the substantially horizontally extending net section. Because the upper side of the dewatering element 40 is arched, it guides the net 30 and defines the turning section. Therefore, the turning roller can be omitted here.
[0030] The fixed suction device 50, which follows the dewatering element 40 in the direction of net travel, is therefore arranged below the substantially horizontally extending section of net 30. Consequently, the waterline of the fibrous material suspension escaping from the outlet gap 24 is also located on the substantially horizontally extending section of net 30. Net 30 is preferably laterally positioned at least in the region between the outlet gap 24 and the waterline. Figure 2 The edge limiter (not shown) restricts the flow of the fibrous material suspension laterally downward from the net 30.
[0031] Optionally, the steam blower 70 and / or the upper mesh 80 can be arranged above a substantially horizontal mesh section. In this way, dehumidification of the fibrous material web can be effectively performed after the water line, or the structural length of the inclined mesh forming device 10 can be reduced to the length required to transfer the fibrous material web with a predetermined dry content to the section of the manufacturing machine adjacent to the inclined mesh forming device 10. Preferably, in the region of the steam blower 70 and / or the upper mesh 80, an additional dewatering element 60 is arranged below the mesh.
[0032] List of reference numerals
[0033] 10' 10' Inclined Mesh Forming Machine
[0034] 20, 20' headbox
[0035] 22, 22' Anterior wall
[0036] 24' Exit Gap
[0037] 30, 30' Net
[0038] 32, 32' breast roller
[0039] 34' First steering roller
[0040] 36, 36' Second steering rollers
[0041] 40' Dehydration element
[0042] 50, 50' Fixed suction device
[0043] 60, 60' additional dehydration elements
[0044] 70 Steam blowing box
[0045] 80 Upper Net
Claims
1. A slant wire forming device (10) for manufacturing fibrous material webs from a suspension of at least one fibrous material, the slant wire forming device having a wire (30) traveling over a peripheral region of a breast roller (32), and subsequently extending at least partially in the direction of wire travel at an angle inclined relative to the horizontal before turning in a substantially horizontal direction at a turning point, wherein, Basically horizontal means having an angle of less than 5° relative to the horizontal line, wherein, in the inclined extension section of the net (30), at least one headbox (20) applies at least a portion of at least one fiber material suspension to the net (30) on the upper side and at least one dewatering element (40) is arranged on the lower side for dewatering at least a portion of the at least one fiber material suspension applied to the net (30), wherein the at least one headbox (20) includes a front wall (22) that, together with the net (30), defines an outlet gap (24) for the at least one fiber material suspension. The feature is that the front wall (22) of the at least one headbox (20) extends beyond the turning portion of the net (30) in the direction of net travel, such that the outlet gap (24) is arranged over a substantially horizontally extending section of the net (30).
2. The oblique mesh forming device (10) according to claim 1. Its features are, At least one dewatering element (40) disposed on the underside of an inclined extended section of the net (30) extends beyond the turning portion of the net (30) in the direction of net travel, thereby terminating the dewatering element below a substantially horizontally extending section of the net (30).
3. The oblique mesh forming device (10) according to claim 1 or 2. Its features are, The front wall (22) of at least one headbox (20) has an arch or bend in the region of the turning part of the net (30), such that the distance between the front wall (22) of at least one headbox (20) and the net (30) decreases in the direction of net travel.
4. The oblique mesh forming device (10) according to claim 1 or 2. Its features are, A fixed suction device (50) is also arranged below the substantially horizontally extending net section, by means of which the position of the water line of at least one fibrous material suspension can be defined on the substantially horizontally extending net section.
5. The oblique mesh forming device (10) according to claim 4. Its features are, After the fixed suction device (50), at least one additional dewatering element (60) is arranged below the substantially horizontally extending web section, by means of which the fibrous material web can be further dewatered.
6. The oblique mesh forming device (10) according to claim 1 or 2. Its features are, At least one steam blowing box (70) is arranged above a generally horizontally extending mesh section.
7. The oblique mesh forming device (10) according to claim 1 or 2. Its features are, At least one upper network (80) is arranged above a network segment that extends substantially horizontally.
8. The oblique mesh forming device (10) according to claim 1 or 2. Its features are, The mesh (30) has low air permeability of less than 410 CFM and / or high retention value of greater than 100 FSI.
9. The oblique mesh forming device (10) according to claim 1 or 2. Its features are, The substantially horizontally extending segments of the net (30) are at least laterally surrounded by edge limiters.
10. The oblique mesh forming device (10) according to claim 3. Its features are, The distance between the front wall (22) of the at least one headbox (20) and the net (30) decreases continuously in the direction of net travel.
11. The oblique mesh forming device (10) according to claim 5. Its features are, The at least one additional dehydration element (60) is a suction box.
12. The oblique mesh forming device (10) according to claim 1. Its features are, The fiber material web is a long-fiber paper web or a wet-laid nonwoven fabric web.
13. The use of the oblique wire forming machine (10) according to any one of claims 1 to 11 for manufacturing long fiber paper webs or wet nonwoven webs.
14. The use according to claim 13, Its features are, The inclined mesh forming machine (10) is operated so that the water line of at least one fiber material suspension appears on a substantially horizontally extending mesh section.
15. The use according to claim 13 or 14, Its features are, The consistency of at least one fiber material suspension is less than 0.3%.
16. The use according to claim 13 or 14, Its features are, The long-fiber paper web or wet-laid nonwoven fabric web has a content of less than 20 g / m². 2 Weight per unit area.
17. The use according to claim 13, Its features are, The inclined wire forming machine (10) is used to manufacture battery separator paper webs or aramid paper webs or capacitor paper webs.
18. The use according to claim 15, Its features are, The consistency of at least one fiber material suspension is less than 0.02%.