DEVICE AND METHOD FOR SPREADING A NONWOVEN FABRIC ON A FORMING BELT

Description

[0001] The present invention relates to a device for scattering a nonwoven fabric on a forming belt, in particular during the production of material panels, according to the preamble of patent claim 1. Furthermore, the invention relates to a method for scattering a nonwoven fabric on a forming belt according to the preamble of patent claim 8.

[0002] In the production of material boards from spreadable material, a mixture of particles or fibrous substances and a binding agent is spread onto a forming or conveyor belt to form a nonwoven fabric. After any necessary pretreatment, this spread mat is then subjected to continuous or discontinuous pressing, which can be carried out using pressure and / or heat. For example, material boards such as MDF (medium-density fiberboard) or OSB (oriented strand board or coarse particle board) can be produced in this way. Pressing usually takes place in a continuous belt press, in which a spread mat is fed to the press by means of a rotating flexible belt, particularly a steel belt. Typically, a plurality of press cylinders exert pressure on the spread mat via the belt, while the spread mat is heated by heating plates.Roller bars are usually arranged between the belt and the press cylinders to reduce friction and to transfer pressure.

[0003] For decades, one of the fundamental challenges of this technology has been the optimal production of nonwovens, also known as pressed material or spread mats, on the aforementioned forming belt. In this process, emphasis is placed on maintaining the specified area weights in width and length as optimally as possible to avoid over- or under-spreading. Over-spreading results in unnecessary material loss for the producer, while under-spreading results in the product's standard values ​​not being met. However, due to current raw material developments and legal requirements, panel producers are now required to use as little material as possible while maintaining consistent properties.In addition to a very precise and uniform scattering, it is also possible to set predetermined density profiles lengthwise and crosswise in the continuously moving fleece in order to be able to produce, for example, a lightweight material panel with predetermined high-density edges or particularly suitable areas of higher density for fittings.

[0004] Suitable methods and devices for producing such nonwovens are known from EP0069162B1, EP0109456A1, EP0230483B1 and EP0292581B1. What all of these disclosures have in common is that a device is arranged between a metering device and a forming belt receiving the nonwoven, in which device the material flow emerging from the metering device is distributed and deposited onto the forming belt to form a nonwoven by means of suitable machine elements. Furthermore, these devices disclose discharge devices which, during the production of the nonwoven and with an adjustable profile across the width of the continuously circulating forming belt, branch off material from the material flow in a targeted manner in order to achieve the predetermined density properties of the nonwoven. Some of these discharge devices also have options for feeding the discharged material to the nonwoven in a metered manner, preferably at a different location or in a more uniform manner.

[0005] It has now become apparent that the devices and the proposed processes are no longer able to meet the requirements of the manufacturing industry for material panels.

[0006] The present invention is based on the object of improving the adjustability of the device for producing a nonwoven fabric compared to the prior art. In an extension of this object, it is particularly intended to prevent the material to be removed from accumulating in front of the openings of the discharge devices or from interfering with each other, thereby making control difficult.

[0007] The invention relates to a device for spreading a nonwoven fabric on a forming belt which circulates endlessly below the device, in particular during the production of material boards from free-flowing material such as fibres or chips, the device comprising an upper inlet opening for feeding the material and a lower outlet opening for discharging the material onto the forming belt, at least one distribution roller and one spreading roller transversely to the transport direction of the forming belt and a discharge device for removing material in sections, wherein a plurality of openings which are adjustable in size are arranged on the discharge device transversely to the transport direction and which are operatively connected to a conveying device for the material passing through the openings in order to separate material from the device.

[0008] The solution to the problem for the above-mentioned device consists in that a cover plate and adjacent to it a plurality of slides with an opening are arranged in the discharge device, wherein in order to adjust the size of the opening the cover plate partially covers the opening and the cover plate and / or the slides are arranged displaceably by means of at least one actuator.

[0009] This solution is based in particular on the realization that it is advantageous if the adjustable openings increase in size in the direction of fall of the material, i.e. preferably have a fixed upper limit and an expanding opening opens downwards towards the forming belt. Conversely, to reduce the opening, the lower limit (on the forming belt side) will move upwards, away from the forming belt. Particularly preferably, an opening will be arranged in the device in such a way that a material flow hitting the discharge device or the openings hits an opening with its upper region and the lower region of the material flow is proportionally deflected downwards towards the forming belt.

[0010] In an advantageous embodiment, the lower end of the cover plate is positioned as the upper limit of the opening in the direction of the material's fall, and the aperture of a slide gate is positioned as the lower limit of the opening. Thus, in the direction of the material's entry into the discharge device, the cover plate is positioned in front of the slide gate.

[0011] In a further advantageous embodiment, in the case of a fixed cover plate for adjusting the opening, the slide with its opening is arranged to be movable essentially opposite to the material flow direction in the device (i.e. from top to bottom in the direction of the forming belt) in order to reduce the opening and in the material flow direction in order to enlarge the opening.

[0012] Alternatively or cumulatively, at least one nozzle for pneumatically cleaning parts of the discharge device, in particular the openings, can be arranged in the discharge device.

[0013] As an alternative to a cover plate, the cover plate can also have an opening and preferably be arranged in a size that essentially covers the movement range of the slides. This essentially covers the slide, and buildup between the slide and the cover plate can be scraped off by sliding them relative to each other.

[0014] Alternatively, an additional cover plate can be arranged opposite the first cover plate to the openings, with the additional cover plate preferably exposing the area of ​​the adjustable openings but covering the remaining area of ​​the slides. A cleaning effect can also be achieved here. At the same time, a predetermined lower drop edge is provided across the width of the forming belt and extending from the discharge device, at which the material remaining in the device is guided toward the forming belt. This eliminates the irregular discharge edges at the lower end of the discharge device, which was previously the case with the prior art.

[0015] The discharge device can preferably be movable to adjust the position or orientation of the openings in the device. In particular, it can also be arranged so that its height is adjustable relative to the forming belt. This allows for improved control depending on the type and / or density of the material or the material mixture. Material mixtures with a high proportion of recycled wood are now increasingly being used, which can exhibit different throwing and distribution characteristics in the device. Changes in the grain size distribution may also make it necessary to reposition the discharge device or change the angle of the discharge device relative to the distribution rollers.

[0016] A preferred control or regulation device will provide a measuring device for the basis weight or the density distribution of the fleece at a predetermined distance from the device and, via the measurement result or a control algorithm interpreting the measurement result, will change the device or the position of the discharge device and / or the slider / cover plates relative to one another in order to achieve the predetermined target value.

[0017] A generic method for spreading a nonwoven fabric on a forming belt which circulates endlessly below a device for spreading material, in particular during the production of material boards from free-flowing material such as fibres or chips, essentially consists in that material is fed into the device through an upper inlet opening and onto the forming belt via a lower outlet opening, and the material is essentially distributed by a distribution roller in the device and transferred to the forming belt by means of at least one spreading roller, and material is removed in sections by a discharge device in the device transversely to the transport direction of the endless forming belt, in that a number of openings which are adjustable in size feed the material passing through to a conveyor device for removal from the device.

[0018] The invention for the method consists in that the adjustable openings of the discharge device are formed by a cover plate and a plurality of slides with openings, wherein the opening of a slide is partially covered by the cover plate to reduce the opening by moving the cover plate and / or the slides towards each other by means of at least one actuator.

[0019] Preferably, in the direction of fall of the material, the lower end of the cover plate is used as the upper limit of the opening and the opening of a slide is used as the lower limit of the opening.

[0020] In order to adjust the opening, it is particularly preferred that the slide with its opening be displaced substantially opposite to the material flow direction to reduce the opening and in the material flow direction to enlarge the opening.

[0021] In order to avoid blockages, at least one nozzle for pneumatic cleaning of parts of the discharge device, in particular the openings, can be used in the discharge device.

[0022] Alternatively, the cover plate can also have an opening and preferably be used in a size that allows the movement range of the slides to be substantially covered.

[0023] On the other hand, a further cover plate can be placed opposite the first cover plate to the openings, whereby the further cover plate exposes the area of ​​the adjustable openings but covers the lower area of ​​the sliders.

[0024] Alternatively or cumulatively, in order to adjust the position or location of the openings in the device, the discharge device can be arranged to be movable, in particular height-adjustable relative to the forming belt.

[0025] It is particularly preferred that the flow of material striking the discharge device is guided to the openings in such a way that the upper part of the flow facing away from the forming belt is guided into the opening and, depending on the size of the opening, the lower region of the flow is deflected, for example held back by the slide and guided downwards in the direction of the forming belt.

[0026] It is understood that the features mentioned above and those to be explained below can be used not only in the combination specified in each case, but also in other combinations or on their own, without departing from the scope of the present invention.

[0027] The invention is described and explained in more detail below using selected embodiments in conjunction with the accompanying drawings. They show: Fig. 1 a longitudinal section through the device according to the invention along the transport direction of the forming belt and Fig. 2 an enlarged view of the discharge device.

[0028] In Figure 1 In a longitudinal section through the device 10 along the transport direction 13 of the continuously circulating forming belt 12, the material flow of the material 1 through the device and the production of the fleece 11 on the forming belt 12 is schematically shown. The material 1 enters the device 10 in the direction of fall 9 through an upper opening, is spread and distributed within the device by at least one distribution roller 14 and finally reaches at least one spreading roller 15 via optional rakes 7, which deposits the material 1 onto the forming belt 12. The optional rakes 7 serve to deflect part of the material and allow part to pass through in the throwing or falling direction in order to enable a predetermined distribution within the device.

[0029] At least one discharge device 2 is arranged in the device 10, which in an exemplary position in the device 10 in Figure 1 is shown and in Figure 2is explained in detail by an enlarged illustration. In the device 10, various material flows are formed by the direction of fall 9 and / or the distribution rollers 14, which can also be controlled accordingly by the optional rakes 7 if necessary. If a part of the material 1 now hits the discharge device 2 as a material flow, the material flow is proportionally deflected downwards in the direction of the forming belt 12 or the spreading rollers 15 and another part is fed through the openings 3, if these are open, in the discharge device 2 to a conveyor device 21, which removes the material 1 from the device 10. As the conveyor device 21, a conveyor screw (not shown) can be arranged along an axis 16 transverse to the forming belt 12 in a screw trough 19 which collects the material 1 and transports the material 1 in the screw trough.

[0030] According to one embodiment, the opening 3 is formed by an opening 6 in a slide 5 and is covered by a cover plate 4 to adjust the size of the opening 3. If the size of an opening 3, which is arranged in a plurality across the width of the device 10, or transversely to the transport direction 13 of the forming belt 12, is to be changed, the corresponding slide 5 with its opening 6 and / or the corresponding cover plate 4 associated with this opening can be moved. The more the cover plate 4 covers the opening 6 of the slide 5, the smaller the opening 3 will be.

[0031] It has surprisingly been found through tests that the adjustability of the device 10 can be significantly improved if the opening 3 is formed from two different movable sheets which together form an adjustable opening 3.

[0032] During operation, adjustability is outstandingly ensured when the upper limit of the opening 3 is arranged substantially at the height of the incoming material 1, and only the lower limit of the opening 3 is adjusted in height, wherein the material 1 preferably only impacts the lower limit of the opening 3 and is deflected in the direction of the forming belt 12. This prevents material 1 impacting above the opening 3 from falling downwards and hindering or even blocking the passage of the material 1 in the passage direction 8 at the height of the opening 3.

[0033] In the exemplary embodiment, an actuator 17 is shown with a connection 18 to a slide 5 in order to move the slide 5. The opening 3 is reduced by the movement of the slide 5 from bottom to top and vice versa enlarged accordingly when the slide 5 is moved downwards by the actuator 17.

[0034] In a further embodiment, an additional cover plate 4' can be arranged, which covers the lower area of ​​the slide 5 and simultaneously prevents material 1 from entering the interior (outside the screw trough 19) of the discharge device 2. The additional cover plate 4' can also be arranged on the other side of the slide 5 in order to avoid any unnecessary friction points for the material 1 sliding along the slide 5.

[0035] A pneumatic nozzle 20 can be arranged within the discharge device 2 in order to convey, in particular, clogging material 1 back into the device 10 or into the screw trough 19. Reference symbol list P1588:

[0036] 1Material 2Discharge device 3Opening 4Cover plate 5Slide 6Breakthrough 7Rake 8Passage direction 9Drop direction 10Device 11Fabric 12Forming belt 13Transport direction 14Distribution roller 15Spreading roller 16Axle 17Actuator 18Connection 5 / 17 19Screw trough 20Nozzle 21Conveyor device

Claims

1. Device for scattering a nonwoven (11) on a continuously circulating forming belt (12) below the device (10), in particular in the course of the production of material boards from free-flowing material (1) such as fibers or chips, wherein the device (10) comprises - an upper inlet opening for feeding the material (1) and a lower outlet opening for discharging the material (1) onto the forming belt (12), - at least one distributing roller (14) and one scattering roller (15) transverse to the transport direction (13) of the forming belt (12), and - a discharge device (2) for removing material (1) in sections, wherein a plurality of openings (3) whose size can be adjusted are arranged on the discharge device (2) transverse to the transport direction (13), which are operatively connected to a conveying device (21) for the material (1) passing through the openings (3) in order to separate material (1) from the device (10), characterized in that a cover plate (4) and a plurality of slides (5) with an aperture (6) are arranged in the discharge device (2), wherein the cover plate (4) partially covers the aperture (6) to adjust the size of the opening (3) and the cover plate and / or the slides (5) are arranged to be displaceable by means of at least one actuator (17).

2. Device according to claim 1, characterized in that, in the direction of fall (19) of the material (1), the lower end of the cover plate (4) is arranged as the upper boundary of the opening (3) and the aperture (6) of a slide (5) is arranged as the lower boundary of the opening (3).

3. Device according to claims 1 or 2, characterized in that, in the event of a stationary cover plate (4) for adjusting the opening (3), the slide (5) is arranged with its aperture (6) so as to be movable substantially counter to the material flow direction for reducing the opening (3) and in the material flow direction for enlarging the opening (3).

4. Device according to one or more of the preceding claims, characterized in that at least one nozzle (20) for pneumatic cleaning of parts of the discharge device (2), in particular the openings (3), is arranged in the discharge device (2).

5. Device according to one or more of the preceding claims, characterized in that the cover plate (4) also has an aperture and is preferably arranged in a size that substantially covers the movement range of the slides (5).

6. Device according to one or more of the preceding claims, characterized in that a further cover plate (4') is arranged opposite the first cover plate (4) with respect to the openings (3), wherein the further cover plate (4') preferably exposes the region of the adjustable openings (3) but covers the further region of the slides (5).

7. Device according to one or more of the preceding claims, characterized in that, in order to adjust the position or the location of the openings (3) in the device (10), the discharge device (2) is arranged so as to be movable, in particular so as to be adjustable in height relative to the forming belt (12).

8. Method for scattering a nonwoven (11) on a continuously circulating forming belt (12) below a device (10) for scattering material (1), in particular in the course of manufacturing material boards from free-flowing material (1) such as fibers or chips, wherein material (1) is conducted into the device (10) through an upper inlet opening and the material (1) is conducted onto the forming belt (12) via a lower outlet opening and the material (1) is distributed substantially by a distributing roller (14) in the device and transferred to the forming belt by means of at least one scattering roller (15) and wherein material (1) is removed in sections by a discharge device (2) in the device (10) transversely to the transport direction (13) of the endless forming belt (12), in that a plurality of openings (3) whose size can be adjusted feed the material (1) passing through to a conveying device (21) for removal from the device (10), characterized in that the adjustable openings (3) of the discharge device (2) are formed by a cover plate (4) and a plurality of slides (5) with apertures (6), wherein the aperture (6) of a slide (5) is partially covered by the cover plate (4) to reduce the size of the opening (3) by moving the cover plate (4) and / or the slides (5) by means of at least one actuator (17).

9. Method according to the preceding method claim, characterized in that, in the direction of fall (9) of the material (1), the lower end of the cover plate (4) is used as the upper boundary of the opening (3) and the aperture (6) of a slide (5) is used as the lower boundary of the opening (3).

10. Method according to one of the preceding method claims, characterized in that, to adjust the opening (3), the slide (5) is displaced with its aperture (6) substantially against the material flow direction to reduce the opening (3) and in the material flow direction to enlarge the opening (3).

11. Method according to one of the preceding method claims, characterized in that at least one nozzle (20) is used in the discharge device (2) for pneumatically cleaning parts of the discharge device (2), in particular the openings (3).

12. Method according to one of the preceding method claims, characterized in that the cover plate (4) also has an aperture and is preferably used in a size which allows it to substantially cover the movement range of the slides (5).

13. Method according to one of the preceding method claims, characterized in that a further cover plate (4') lies opposite the first cover plate (4) to the openings (3), wherein the further cover plate (4') exposes the region of the adjustable openings (3) but covers the lower region of the slides (5).

14. Method according to one of the preceding method claims, characterized in that, in order to adjust the position or the location of the openings (3) in the device (10), the discharge device (2) is arranged so as to be movable, in particular so as to be adjustable in height relative to the forming belt (12).

15. Method according to one of the preceding method claims, characterized in that the stream of material (1) striking the discharge device (2) is guided onto the openings (3) in such a way that the upper part of the stream facing away from the forming belt is guided into the opening (3) and, depending on the size of the opening (3), the lower region is held back by the slide (5) and guided downwards in the direction of the forming belt (12).