DE803085C - Method and device for the production of thick-walled molded fibrous material - Google Patents

Description

(WiGBl. P. 175)

property

German Patent Office

ISSUED FEBRUARY 26, 1951

p 24188 VII154e D

Heinz Tönniges in Krefeld

has been named as the inventor

Fibrous briquettes

It is known to attach thick-walled fibrous material moldings to sieve molds using mold punches to produce, which are introduced into the sieve mold either from above or from below, thereby Press the pulp in front of you and finally part of the fiber deposit from the Squeeze out the water in it. Due to the direct contact between the forming die and Fiber precipitation creates a smooth inner surface. The disadvantage of the process is the high Costs for the molding die, their precise guidance and control.

Attempts have therefore already been made to produce thick-walled molded fibrous articles without the use of molding punches by feeding the pulp slurry from above to the sieve mold under pressure and after precipitation has taken place, a certain amount of postpressing or partial drying of the molding takes place by a supplied air-like medium (compressed air, steam, gas). This procedure ao but requires special care when feeding the pulp. With that namely the The molding does not adhere to the sieve mold in an impermissible manner, it is necessary to do this before it is let in to fill the pulp with water so that the first part of the pulp is caught in it and an immediate impact of the fabric on the wire is avoided. The latter would become As a result, damage to its surface occurs when the molding is removed from the mold and that the fibers which have penetrated the pores of the screen contaminate the same.

The present invention is a method and an apparatus in which neither

a molding die or pre-fill water are required and moldings can still be produced, which do not adhere to the forming screen and have good internal smoothness.

The method consists in that the pulp slurry from below without predilution at first low, but then strongly increased pressure into the interior of a sieve mold that is open at the bottom is introduced and that after reaching

ίο the desired wall thickness of the molding that is in Residual amount of fibrous material that has not yet been precipitated inside the mold at essentially maintained pressure while supplying an air-shaped Medium is quickly drained downwards, whereupon the pressure medium precipitates the fibers penetrates itself and thereby removes part of the fibrous water to the outside.

The slow rise of the undiluted pulp according to the invention from below at the beginning

ao the supply of material means that the fibers that reach the sieve first have no reason to to penetrate significantly into the pores of the sieve shape, all the more so than they so to speak among themselves are bound. So they behave more favorably than when they are strong with pre-fill water would be diluted. One obtains therefore moldings, which are particularly easy and undamaged from the Take out the mold and the sieve molds used will stay clean for a long time.

According to the invention, it is also important that the remaining amount of pulp that is still in the after reaching the desired wall thickness Located inside the mold, so that it can be removed quickly and without vortices downwards, on the one hand no rinsing or other damage to the then still sensitive inner layer of the fiber deposit can occur, and that on the other hand there is no time during which the discharged Substance residue due to its further precipitation reduces the wall thickness of the molding downwards increase noticeably and thus disturb the uniformity of the walls. For the purpose is, as already stated, the air-shaped medium supplied under a pressure that the Pressure under which the pulp was immediately before the residual quantum was released, almost equals or even exceeds it.

When applying sufficiently high pressure "during and after the deposition of the substance on the sieve mold according to the invention moldings are produced which largely pre-dewatered with high wet strength are so that they can be removed without difficulty and further processing, e.g. B. Post-pressing, final drying, impregnation, etc., can be supplied.

The drawing shows a simple embodiment of the device according to the invention. This means ο the shape of the sieve, b the fiber deposit formed on it, c a feed line for the pulp, d a feed line for the air-shaped medium, e a discharge line for the pulp residue. All lines are located on the pot /, from which the shape α can be lifted off after the molding b has been formed, so that it can be pivoted to the side, for example, to remove the molding. The opening g through which the air pressure medium enters the pulp is shaped according to the invention in such a way that flushing effects are avoided. For example, the line head can be designed in such a way that the air enters with eddy-free rotation, with only tangential but not radial forces acting on the sensitive inner skin of the molded article as a result of the resulting rotation of the pulp residue.

The line d can also be raised and lowered so that it is in the uppermost part of the mold at the beginning of the entry of the air-shaped medium at h , with disruptive flushing effects being particularly effectively prevented.

Claims (5)

Patent claims: 1. A process for the production of thick-walled fibrous material moldings on sieve molds, thereby characterized that pulp from below under initially weak, but then vigorously increased pressure is introduced into the interior of a sieve mold that is open at the bottom and that after reaching the desired wall thickness of the molding inside the Remaining amount of fibrous material that has not yet been precipitated in the form, with the addition of an air-shaped one Medium is quickly drained, whereupon the latter continues to penetrate the fiber precipitate and thereby part of the water contained therein removed to the outside. ■ 2. The method according to claim 1, characterized in that that the pressure of the gaseous medium during the removal of the residual amount of fibrous material the pressure under which the pulp was before the remainder was discharged, is almost equal to or exceeds it. 3. Device for performing the method according to claim 1 or 2, characterized through a sieve form open at the bottom, a vortex-free feed of the pulp from below upwards and a supply line for an air-shaped medium, which is connected to such an opening is provided that the exiting medium does not remove the already molded fiber deposit can damage it through the flushing action. 4. Apparatus according to claim 3, characterized in that the outlet opening for the air-shaped medium is shaped so that the exit takes place under rotation. 5. Apparatus according to claim 3 or 4, characterized in that the supply line for the air-shaped medium can be raised and lowered. 1 sheet of drawings 1 3590 2.