Patent Application
20230235493
The present invention relates to an air laying device for producing a fibrous mat, including, at least partially, wood pulp fibers and/or cellulose fibers.
Devices of this type are known. Initially, individual fibers or fiber agglomerates are produced and are distributed uniformly by way of an air stream on a forming fabric in order to form a fibrous mat. Air laying devices for laboratory operations are operated in batch mode. Individual fibrous mats, so-called fibrous mat sheets, are produced in a laboratory successively for further examination with respect to properties, for example mechanical properties. Such devices operate very slowly and must be hand-fed. The provision of single fibers by way of breaking down fiber agglomerates is particularly expensive.
Air laying devices which produce fibrous mat webs in continuous operation are also known. The provision of single fibers by way of breaking down fiber agglomerates is expensive also in this case.
The known devices also have the disadvantage that aggregates, for example powder, are difficult to mix uniformly with the fibers in the air stream. Secondly, it is difficult to process fibers with a large fiber length spectrum.
What is needed in the art is an air laying device which improves the known devices in regard to the described disadvantages.
The present invention provides an air laying device for producing a fibrous mat, consisting at least partially of wood pulp fibers and/or cellulose fibers, the air laying device including a ring distributor having a fiber feed, a ring channel with an outlet element forming a section of the ring channel, wherein said section is arranged within a calming channel extending in downward direction toward a forming fabric, and wherein the outlet element has openings through which fibers supplied by the fiber feed can exit from the ring channel into the calming channel and can move to the forming fabric to form the fibrous mat on said forming fabric.
The ring channel of the ring distributor is designed advantageously so that the fibers and possibly the fiber agglomerates and the aggregates move in an annular flow produced by an air stream. A portion of the fibers and, if present, a portion of the aggregates leave the ring channel via the outlet element and pass directly into the calming channel and then onto the forming fabric to form a fibrous mat or a fibrous mat web. In the annular flow the fiber agglomerates are broken down into individual fibers. Before the fibers leave the ring channel, they are optionally transported several times in a circle by the annular flow. The multiple circulations improve the breakdown of fiber agglomerates on the one hand and achieve a homogeneous mixture of the solids in the air stream on the other hand.
Wood pulp fibers and/or cellulose fibers and/or aggregates are fed advantageously into the air stream by the fiber feed.
In the area of the fiber feed, an air nozzle can be used as a propulsion jet nozzle to generate a negative pressure in the fiber feed.
In an advantageous embodiment, several air nozzles open into the ring channel to generate an air stream and to break down fiber agglomerates. On the one hand, this maintains and propels the annular flow, and on the other hand, the air jets of the air nozzles generate pressure pulses on the fiber agglomerates so that they are broken down.
In a possible further development of the present invention, cleaning nozzles are arranged outside of the ring channel for the purpose of cleaning the openings of the outlet element. These are optionally in the embodiment of air nozzles.
The air nozzles and/or cleaning nozzles can be supplied with a pulsating or oscillating air stream.
The air nozzles and/or the cleaning nozzles can be mounted fixed or movably. This allows the impetus of the annular flow as well as the cleaning effect to be adjusted. The movably mounted nozzles can be designed for oscillating movement.
The calming channel may terminate, providing a seal with the forming fabric or can be spaced at a distance from the forming fabric.
The calming channel can be supplied with an overpressure.
A suction device can be assigned to the forming fabric. This supports the deposit of fibers and a more compact fibrous mat can be produced.
The openings of the outlet element can have a maximum width of 10 mm.
The openings may be designed as a slot or can be round.
In a possible further development, the ring channel may contain mixing particles for mixing the fibers and breaking down of fiber agglomerates.
The air laying device can be designed to be suitable for laboratory use and the forming fabric can be arranged statically. The feed can be designed to be closable for this case. Thus, the production of a fibrous mat can be carried out in batch operation.
The air laying device can also be designed to be suitable for continuous production of fibrous mat webs, wherein the forming fabric can be movable in machine direction. Optionally, it is designed as a circulating belt guided over several rollers.
Additional characteristics and advantages of the present invention result from the following description of design examples with reference to the drawings.
The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become more apparent and the invention will be better understood by reference to the following description of embodiments of the invention taken in conjunction with the accompanying drawing, wherein:
Corresponding reference characters indicate corresponding parts throughout the several views. The exemplifications set out herein illustrate at least one embodiment of the invention, and such exemplifications are not to be construed as limiting the scope of the invention in any manner.
Corresponding elements in the drawings are identified with same reference numbers. The functions of such elements in the individual drawings correspond with each other unless otherwise described and no contradictions occur. A repeated description is therefore dispensed with.
While this invention has been described with respect to at least one embodiment, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2020 125 404.0 | Sep 2020 | DE | national |
This is a continuation of PCT application no. PCT/EP2021/076003, entitled “AIR-LAYING DEVICE”, filed Sep. 22, 2021, which is incorporated herein by reference. PCT application no. PCT/EP2021/076003 claims priority to German patent application no. 10 2020 125 404.0, filed Sep. 29, 2020, which is incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/EP2021/076003 | Sep 2021 | US |
| Child | 18127854 | US |
