FI80093C - AVVATTNINGSELEMENT FOER VAOTPARTIET I EN PAPPERSMASKIN. - Google Patents

Description

80093

The present invention relates to a strip-shaped dewatering element for a wire or felt part of a pulp dewatering machine, in particular a paper machine, such as a wire table, foil, chest, squeegee, wet wiper, the coating in sliding contact with the individual consists of individual segments of hard material, such as sintered alumina, silicon carbide or the like, located opposite the impact surfaces (5) and with a stop on the wire-side side, the individual segments being fixed to the machine its transverse direction of the Prof.Carbon, which in turn is mounted on the support structure of the dewatering machine and the individual segments are joined together by gluing (US-A-4,047,993).

List-shaped dewatering elements for the wire or felt part of a pulp dewatering machine, consisting of individual segments which are in hard material communication with other materials, are known. The introduction of dewatering elements with hard materials has enabled the advantageous high operating speeds of mass dewatering machines in use today.

The structure of the dewatering elements from the individual segments is necessary because the pieces of hard materials cannot be made in one piece with an arbitrary size of surface, as is possible in the case of plastics, for example.

One crucial disadvantage of a segmental structure is that the joints between the individual segments can damage the wire and felt and cause defects in the paper being produced, such as water streaks - especially when there are manufacturing clearances between the individual segments. This disadvantage can be eliminated by over-grinding the pre-assembled drainage element by the manufacturer. Nevertheless, cracks may occur at the joints when the dewatering element is stressed due to bending, torsion and / or thermal expansion.

EP 00 00 691 discloses the gluing of segments of hard material with a lower part of steatite, the steatite lower parts being displaced relative to the elements of hard material. The adhesive used is an artificial resin which is so elastic that it is able to compensate for various thermal expansions without being destroyed. In practice, a gap is formed between the individual elements in the hard material, into which the adhesive forms a convex bridge, but which nevertheless extends below the contact point of the ceramic strip and the wire so as to act on the vacuum behind the strip. The same phenomenon is even more pronounced in the solution disclosed in GB A 1 232 681, which can also consist of individual segments with longitudinal ends with stepped mounting surfaces stepped over the entire width of the segment, where the wire-supporting hard material parts are located in non-brittle plastic such as polyethylene. Polyethylene expands more strongly as a hardener when heated and grinds against the wire. If the machine then cools down due to different operating conditions, there is a lack of abraded material in the butt seam and thus this structure is also detrimental to the vacuum and thus leads to paper streaks.

It is now an object of the present invention to provide a strip-shaped dewatering element for a wire or felt part of a pulp dewatering machine which does not form any shoulders, steps or cracks in the longitudinal direction of bending stress, torsional stress or thermal expansion. , which is simple to install and safe and simple to handle.

The task is solved according to the invention according to the appended claim 1.

The advantage of the present invention is that due to the overlapping gluing fastenings of the individual segments, a structure is created which, from the point of view of strength, can be considered as a self-supporting dewatering element and which as such can be handled safely. Since the top and the response are materials with the same coefficient of thermal expansion, there are no forces due to thermal expansion in this assembly as the temperature fluctuates, which would lead to deformation or distortion, especially at stepped interfaces, and thus failure of the component.

Compared to the butt adhesive joint, the force- and shape-resistant overlapping adhesive fastenings make it possible to considerably increase the surfaces to be connected to one another and thus to reduce the specific surface stress.

Since the critical shear strength of the adhesive joint is higher than the critical static strength of the selected ceramic hardeners, no plastic or elastic deformation or associated deformation of the strip-shaped dewatering element occurs at the stepped interfaces.

Commonly known materials can be used to perform the gluing operation when they reach the required high strength. Particularly suitable for this use are 2 component adhesives based on epoxy resin, whereby the joints thus made, due to the required curing time of the adhesive, still allow the individual segments to be re-oriented after joining.

According to the invention, the segments of hard material are not one part and are not treated by grinding, but are formed of separately made tops and stops, which are joined together by an overlapping adhesive seam. The top and the response are preferably of the same material, in which case they have the same material properties.

However, the response is not subject to the same requirements in terms of grain size distribution, surface hardness, pore volume, pore distribution, grindability and polishability as the top. Thus, it is advantageous to use raw materials which only satisfy the requirements in terms of strength and coefficient of thermal expansion, while the top in contact with the wire or felt should have as few pores as possible so that no filler particles can accumulate, which in turn lead to the wire. - or felt damage. The pores in the response, on the other hand, are even preferred because they improve the adhesion of the adhesive. The response can be made, for example, from waste obtained during the processing of raw parts.

The gluing interface must be identical to the neutral axis of the overall cross-section or may be located above the neutral axis. If the interface is located on the neutral shaft, no tensile, compressive or other stresses are generated. If the interface is located above the neutral axis, only the compressive stresses will stress the adhesive layer. In this way, a high level of connection safety is guaranteed. If the adhesive layer were to be subjected to peeling, the safety of the joint would be only a fraction of that of the push or shear stress.

The following drawing further illustrates the invention without limiting the invention to the embodiments shown, in which:

Fig. 1 shows a side view of a dewatering element according to the invention in the transverse direction of use of the machine.

Fig. 2 shows a section along the plane of the line V-V in Fig. 1.

Fig. 3 is a perspective view of another dewatering element according to the embodiment.

Fig. 4 shows a section of a dewatering element provided with a profile strip and a support structure of a pulp dewatering machine.

Figure 1 shows a two-part segment 1 comprising a top part 2 and a stop 3, which can be manufactured individually and are easy to machine. The upper part 2 and the stop 3 are of equal length and are each time displaced relative to each other by half the length and are fastened by their horizontal adhesive mounting surfaces 4 by means of an adhesive layer 8. The upper part 2 is joined by an adjacent upper part 2. This is again connected to both components by means of a horizontal and vertical connecting surface 4 and 5 by means of an adhesive layer 8. This structure is repeated by alternately setting the stop 3 and the upper part 2 until the desired length of the dewatering element is reached.

Fig. 2 shows a section of the dewatering element in a plane corresponding to the section line IV-IV in Fig. 1. The top 2 is foil. The connection to the stop 3 is made by means of an adhesive layer 8. The stop 3 is T-shaped in cross section. The dewatering element is connected to the support structure by means of the profile strip 9 shown in Fig. 4.

Figure 3 is a perspective view of a dewatering element according to another embodiment. The structure consists of another two-part yksittäissegmenteistä of travel of the wire 1. 6 80 093 6 by the arrow direction indicated. The upper part 2 is a foil and is wider than the stop 3. The stop 3 is provided with a dovetail cross-section for joining the profile strip not shown. The thickness of the abutment part 3 in the vertical direction is greater than the thickness of the upper part 2. 2 the upper part of the structure is the same length as the response of three, and has been rakennepituu the half-way with response 3 and is fixed thereto by means of eight liimaker-layer.

Figure 4 shows a vertical section of the dewatering element when it is mounted on the support structure of the mass dewatering machine. 2 the upper part of the contact surface 11 contacts the wire or felt, whose direction of travel is indicated by arrow 6 by means of. A stop 3, which has a trapezoidal cross-section, regularly connected to the upper part 2, engages a profile strip 9 made of plastic, fiberglass-reinforced plastic or metal. The profile strip 9, in turn, adheres to the T-shaped metal profile 12 of the pulp dewatering machine structure 10. The dewatering segment, the stop 3 of which is in the recess of the profile strip 9, can move freely only in the transverse direction of the wire. In the same way, the profile strip 9 can only move in the transverse direction of the wire with a T-shaped metal profile 12 with its support structures 10. This structure compensates for thermal expansions in the assembled structure by sliding so that the dewatering elements are not subjected to bending stresses.

Il

Claims (3)

1. Shaped dewatering element for the wire or felt part of a dewatering machine for fiber material, in particular a paper machine, such as wire table, foil, support table, liquid vacuum cleaner, vacuum cleaner, vacuum cleaner, felt vacuum cleaner, which in sliding contact with the wire or felt Standing coating consists of individual segments (1) of hardeners, such as sintered aluminum oxide, silicon carbide and the like, which with their abutment surfaces (5) lying next to each other on the side facing away from the wire side have a ledge (3) and wherein the individual the segments (1) are fixed to a profile bar (9) extending transversely to the running direction of the machine, which is also arranged on the side structure of the drainage machine (10) and the individual segments (1) are connected to each other by means of adhesive. characterized in that the segments (1) consist of a separately sintered upper part (2) and a similarly sintered lower part (ledge 3) which have the same coefficient of thermal expansion that they with the other joined vertical impact surfaces (5) and the horizontal contact surfaces (4), respectively, are arranged such that the upper part (2) and the ledge (3) are displaced relative to each other in the longitudinal direction of the dewatering machine. 2. Shaped dewatering element according to claim 1, characterized in that the upper part (2) and the ledge (3) are reinforced with the same material. 3. Shaped dewatering element according to one of Claims 1 or 2, characterized in that the cross-section of the overall profile consisting of the ledge (3) and the upper part (2) is chosen so that the neutral axis of the total cross-section extends parallel to the longitudinal axis of the dewatering machine and in the plane of the horizontal adhesive joint (touch surface 4).