FI109816B - Press jacket and method of making a press jacket - Google Patents

Description

109816

Compression diaper and method for making a compression diaper

BACKGROUND OF THE INVENTION The present invention relates to a press diaper for a press device for removing water from a pulp web, in particular to remove water from a paper web at press 5 of a papermaking machine having a belt having an inner layer facing elastomeric matrix material disposed therein wear resistant layer. Such a compression jacket is known from US-A-4 978 428.

Such press nappies are used, in particular, in a press machine for a paper machine to remove water from a moving pulp web, an aqueous paper web. Such a clamping device has two clamping portions (e.g., two clamping rollers or one clamping roller and one clamping shoe) which form a clamping point with one another. Through this press point, the pulp web to be dried passes along with the press diaper and possibly with one or two felt belts. The compression sheath is generally endless and may have a different length when viewed in the direction of travel of the web. In the case of long press diapers such as GB-A-2 106 555, the press diaper extends beyond the press point over the guide rollers. On the other hand, if the compression sheath is relatively short in the direction of rotation, it forms a tubular compression sheath which circulates a substantially circular path outside the clamping point.

20 These types of press diapers are subjected to heavy stresses in use. Compression-. '' *: High compression and swelling stresses occur, leading to ··· premature wear of the compression sheath. In particular, considerable abrasion occurs on the upper surface of the compression sheath facing the i · · t: mass path. With conventional rollers, this results in a change in the compression of the press sheath at the press point and hence the drying power • »25. With shoe press clamps, this results in a change in pressure • | »':. 'As well as changing drying conditions.

In addition, ribbed compression shells are known (US-A-4 559 106, WO-A-92/02678, US-A-4 478 428, US-A-5,062,924) to improve dewatering capability. ' ''; in the pinch area. Also, such grooved clamping diapers are subject to the same stresses as above, so that due to the weakening of the grooves and the 'tensile and shear stresses occurring in the larger groove area, an even greater 1 · · ·' wear occurs in the groove area. .

For this reason, according to the aforementioned US-A-4 978 428, the outer layer facing up to the pulp web has a higher hardness than the layer below it.

It has turned out that in such a structure, where the harder layer is placed on a softer layer, there is a danger of the two layers being separated from each other and hence the risk of the compression mantle breaking.

It is therefore an object of the invention to provide an improved compression sheath which avoids the drawbacks of the prior art and in particular has a high durability and low abrasion. Further, a suitable method for preparing such is provided.

With respect to the compression sheath, this task is solved according to claim 1, wherein in the above-mentioned type of compression sheath, the wear-resistant layer is made of the same or similar matrix material as the inner layer and is reinforced with embedded wear-resistant particles.

The fact that the wear-resistant layer consists of the same or chemically similar matrix material as the inner layer ensures a good bond between the two layers so as to avoid detaching the outer layer from the inner layer even under long-term use. The insertion of wear-resistant particles of this matrix material strongly increases the wear resistance of the joint thus formed, whereby other mechanical properties, in particular spring-resistance and strength, are substantially determined by the properties of the matrix material. • ... * This requires that only a small amount of wear-resistant particles be introduced so that, overall, an insertion structure is formed which: ; rice forms the matrix material. In the case of wear-resistant particles less than 50% by volume ·: ·:% is basically such a case. In general, only less abrasive particles are used, preferably in the range of about 1% ·. ·. % by volume - 30% by volume, whereby the optimum mixing ratio can be determined experimentally and influenced by the operating conditions and the properties of the matrix material ..., and the embedded wear-resistant particles.

As matrix material, for example, polyurethane can be used, whereas wear can be used. The durable particles may consist of, for example, rock flour, especially granite flour, · · ·. ceramic powder, in particular alumina powder, or glass material.

In a preferred embodiment of the invention, the reinforcing wires have a pulp current transversely; longitudinal yarns with respect to the skeleton, on which are laid helically 3 109816 transverse yarns extending substantially in the flow direction of the pulp and extending to the periphery of the belt.

Although the present pressing diapers, which are pulled at their edges on the carrier discs, have the greatest possible flexibility due to the attachment to the carrier disks, especially at the periphery (cf. DE-A-3 909 936), according to the invention in a direction so that the clamping jacket of the invention can be advantageously used on the carrier discs to ensure a better passage of the pulp web at the point of compression.

In another preferred embodiment of the invention, the abrasion-resistant layer extends only between the two lateral edge regions over a limited belt compression area.

This achieves that the belt has a high strength at the periphery to enable operation with the support discs, but on the other hand the belt's central compression region provides the necessary reinforcement to increase wear resistance so as to provide sufficient flexibility at the periphery as well as before tensioning the carrier discs.

As to the process, the object of the invention is solved by the method of applying a first layer of the first elastomeric matrix material to the casting and then wrapping the reinforcing yarns, and then, before curing the first layer of the first layer of the second layer. a mixture of matrix material and wear - resistant particles;

. '. Since the second layer is applied in the casting process before the first layer is cured, a durable connection on the surfaces between the two layers is guaranteed, so that the separation of the two layers, even during long-term operation at high stresses, is excluded.

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. '' '; In a preferred embodiment of this process, the second matrix material and the first matrix material are identical or chemically similar.

• »·: \\: 30 With these steps, the connection between the two layers is still improved so that it will work. When identical matrix materials are deposited on both layers, a practically single continuous layer is formed, with only wear-resistant particles being deposited on the outer layer.

4, 109816

It will be appreciated that the above-mentioned features, which will be further described below, are applicable not only to the particular combination in question, but also to other combinations or individual settings without departing from the scope of the present invention.

Other features and advantages of the invention will be apparent from the following description of the preferred embodiment. In the drawings: Figure 1 is a cross-sectional view of a press diaper according to the invention; Fig. 2 is an enlarged sectional view of the compression jacket of the invention of Fig. 1; Fig. 3 shows a simplified representation of a press device in the area of a press point, and Fig. 4 shows a simplified schematic sectional view of a device for making a press jacket.

The compression sheath according to the invention is marked in its entirety in Figures 1-3 as 10.

Figure 3 illustrates the conditions at the press point 34 of a known type of shoe press in which the press sheath 10 rotates about the press shoe 28 between the counter roll 26, whereby the pulp web 30 in the form of an aqueous paper web is passed between the counter roll 26 and the felt web 32. Due to the high pressure "···" at the press point 34, water from the pulp web 30 is discharged at the press point 20, whereby the web 32 receives water.

.,.,: According to Figures 1 and 2, the clamping mantle 10 has an endless tubular belt 11 which is reinforced in its central region, the clamping region 11. The belt 11 consists of a first inner layer 20 and a radially outer second layer 22, which is located only in the compression region 12, the inner layer 20 extending across the entire cross-section of the belt 11 to both edge regions 14.

• · · ": The belt 11 is reinforced with reinforcing yarns 16, 18 in the following manner, in more detail.

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: "T>: The reinforcing wires 16, 18 of the belt 11 consist of a radially inner mass web, '. 30 of mutually parallel longitudinal yarns 16 extending at about equal distances between the two edges of the belt 11 and transversely extending, also substantially in the direction of mass flow, of the yarns 18, is spirally wound on the longitudinal yarns 16, as will be explained in more detail later with reference to FIG.

Both the first layer 20 and the second layer 22 consist of an elastomeric matrix material, preferably polyurethane, with the second layer 22 further comprising approximately 10% by volume of particles 24 consisting of granite flour.

In the second layer 22, prior to the placement of the matrix material, a flowable, homogeneous mixture of the matrix material and approximately 10% by volume granite flour 24 is prepared in the casting process. The manufacture of a press jacket is carried out in a manner known per se as described separately in DE-A-37 15 153.

The device 50 for manufacturing the clamping mantle 10 has a cylindrical casting member 38 with longitudinal threads 16 tensioned parallel to each other at predetermined distances from the upper surface thereof. The first tube 46 is fed along the top of the first polyurethane casting nozzle 40 through 15 while the molding 44 is rotated in the arrow direction around the central axis 52 and the casting die 40 is mounted on the support parallel to the central axis 52, so that a continuous casting stage, to gradually form a cylindrical envelope surface. The casting material then passes through the longitudinal yarns 16 to the casting member 38 and forms the inner layer 20 of the compression sheath.

At the same time, at the same time, a transverse strand 18, which is long - * ...: on the outside of the threads 16, is wound spirally.

Thus, in a manner known per se, the first inner layer 20 of the pressing diaper 10 is formed.

In accordance with the invention, the second outer layer 22 is applied simultaneously through a second lance nozzle 42, which is relatively less distant from the first lance nozzle 40. Through this second lance nozzle 42, a tube is fed: of the matrix material as the first tube. '1': 46 feed material replaced by 10% by volume granite flour.

In that the second outer layer 22 consists of the same matrix material as the first layer 20 and is applied over the first layer 20 by molding before '. once this has cured, an optimal bond is formed between the two layers 20, 22. At the same time, the wear-resistant particles 24 embedded in the second layer 22 are at the same time assured of high wear resistance of the compression sheath 10.

Claims (4)

A press jacket for a press device for dewatering a pulp web (30), in particular dewatering a paper web at the press point (34) of a paper machine, the press mantebi having a belt (10) with an inner layer (20) of an elastomeric mat. rice material turned away from the pulp web (30), in which embedded reinforcement trees (16, 18) and on which is placed an outer wear resistant layer (22) facing the pulp web (30), characterized in that the wear resistant layer (22) consists of the same or similar material. matrix material such as the inner layer (20) and it has been reinforced with incorporated wear resistant particles (24), that in the reinforcing trees longitudinal trees (16) are found transversely to the direction of movement of the pulp (36), on which are placed helical transverse trees (18). runs substantially in the direction of movement of the pulp (36) and all the way to the rim area (14) of the belt (10) and that the wear-resistant layer reaches only above the pressing area (12) of the belt (10) between the two lateral peripheral regions. Press jacket according to claim 1, characterized in that the wear-resistant particles (24) consist of stone flour, ceramic powder or glass material. Method for making the press jacket according to claim 1 or 2, wherein the first layer (20) of a first elastomeric matrix material is cast on a casting piece (38) and the reinforcing trees (16, 18) are then wound, characterized in that before the first layer ( 20) is cured, the second layer (22) is cast on the first layer (20) which consists of a mixture of a second matrix material and wear resistant particles (24). Method according to claim 3, characterized in that the second matrix material ..!: 'And the first matrix material are identical or chemically similar. • · • »» · • · • * t lit · I i <»*