DE2922025A1 - Paper making fourdrinier wire - has stitched longitudinal reinforcement seams at the side zones - Google Patents

Abstract

The fourdrinier wire for a paper making machine is fitted with a number of stitched longitudinal seams as a reinforcement,at a narrow gap from the side edges. They are formed from abrasion resistant material or narrow strips of plastics applied while molten. Pref. a multi-filament polyamide, impregnated with resins such as formaldehyde or acrylic resin is used as the sewing thread for the seams. Pref. the lower thread is of a material which has a higher resistance to abrasion than the upper thread. Pref. the seaming is applied after the fourdrinier wire has been mfd. The construction provides a reinforcement for the fourdrinier wire at the zones where there is the greatest risk of tearing and shearing, so that its useful life is increased.

Description

Screen for paper machines and processes

for the production of such a sieve " The invention refers to a screen for paper machines, consisting of a synthetic fabric Fibers. Werner is the subject of the invention a method for producing a such sieve.

It is a known problem that the runtime resp.

Service life of synthetic sieves due to greatly increased abrasion in certain zones of the web, mostly in the area of the format limit, is limited. This Sanding down can sometimes be more than twice as high as in the sheet-forming part of the screen is usually limited to a strip width of about lo to 50 mm and can at these points lead to the formation of longitudinal cracks, which change the Make sieves necessary.

The invention has set itself the goal of a sieve of the initially to create the type mentioned, in which in a simple way the endangered zones in such a way are reinforced so that no premature cracking is to be feared at these points, so that the service life of the sieve is extended. This is achieved by the invention underlying goal by keeping the sieve a short distance from its edges Reinforcements in the form of several quilted longitudinal seams made of wear-resistant material or a narrow strip of plastic applied in a molten state having.

These made of wear-resistant material and quite close together delay lying reinforcements essentially the grind of the sieve. The paper web is not adversely affected because they are at risk Zones are mostly outside or at most in the spray edge. When using Change strips in the form of plastic applied in a molten state the strips do not touch the paper side of the screen at all, as the strips are only on the running side protrude beyond the tissue level.

A variety of materials can be used as the sewing thread, provided that it is used they are sufficiently wear-resistant.

However, polyamide multifiles are particularly advantageous.

To prevent these yarns from fraying, you can use resins e.g. formaldehyde, acrylic resin or similar materials.

Fabrics made from synthetic fibers often have to undergo post-treatment processes after weaving are subjected, which are often associated with a heat treatment. In the course of This post-treatment can, also through targeted stretching, the width of the sieve change. It is therefore advantageous for the production of a sieve according to the invention, to apply the longitudinal seams after the other completion of the screen. Since the Longitudinal seams are therefore applied as the last work step, there is a guarantee that that these longitudinal seams actually run in the desired area.

Below is the invention with reference to the accompanying drawings explained in more detail. 1 shows schematically one with reinforcements according to the invention provided sieve and FIG. 2 shows a cross-section on a greatly enlarged scale through this sieve.

The screen 2 running over rollers 1 consists of a synthetic fabric Fibers. According to FIG. 2, this fabric has transverse threads 3 and longitudinal threads 4.

At a small distance from the edges 5 and 6 of the sieve there are 2 now according to the invention several reinforcements 7 applied, which are close to one another. According to Pig. 2, the reinforcements 7 are designed as longitudinal seams, the one Have bobbin thread 8 and an upper thread 9. The bobbin thread 8 can be made of more wear-resistant Material exist as the upper thread 9. The lower threads protrude over the through the transverse threads 3 and longitudinal threads 4 before certain surface of the screen 2 and therefore act as before all stressed wear parts. The extent to which the bobbin threads protrude can be can be varied by the tension of the longitudinal seams. When the tension is greater, it will be the bobbin threads are pressed further into the cross threads.

The reinforcements 7 can, however, also take the form of relatively thin strips consist of plastic, which is in a molten state by means of nozzles on the sieve 6th was applied. The plastic used here is e.g.

Polyamide, polyester, polyvinyl chloride and the like.

Claims (5)

P a t e n t a n s p r ü c h e Screen for paper machines, consisting of from a fabric of synthetic measles, characterized in that the sieve (2) at a small distance from its edges (5,6) reinforcements in the form of several quilted ones Longitudinal seams (7) made of wear-resistant material or narrow strips made of molten material Has state applied plastic. 2. Sieve according to claim 1, characterized in that the sewing thread for the longitudinal seams (7) are polyamide multifilaments. 3. Sieve according to claim 2, characterized in that the polyamide multifile are impregnated with resins e.g. formaldehyde, acrylic resin or similar materials. 4. Sieve according to one of claims 1 to 5, characterized in that that the lower threads (8) of the longitudinal seams (7) made of a more wear-resistant material exist as the upper threads (9). 5. A method for producing a screen according to any one of the claims 1 to 4, characterized in that the longitudinal seams after the rest of the finishing of the screen are applied.