FI67898C - SPIRALVIRA OCH FOERFARANDE FOER DESS TILLVERKNING - Google Patents

Description

67898

The present invention relates to a helical wire, in particular to a paper machine drying wire, which consists of - transverse yarn spirals arranged side by side in the longitudinal direction of the wire, the threads of the adjacent helices being interleaved with each other, and - fillers located in the free interior of the wire spirals to limit the air permeability of the wire.

The helical wire, which is made by connecting the wire spirals in pairs with connecting wires in a web, is very open due to the structure, whereby the air permeability may be 18000 m / m h at a measuring pressure of 100 Pa. Such a wire is not suitable for all paper machines due to its high air permeability. Namely, a wire that is too open causes it to be easily blown on a paper machine, which means that so much wire passes through the wire that the web comes off the surface of the wire. This easily causes the web to break. As a result, the wire manufacturer 25 often has to reduce the permeability of the wire to make it suitable for a paper machine drying wire.

It is previously known from DE-A-3 039 873 and 2 419 751 to reduce the air permeability of a spiral wire by filling the free ti-30 lats remaining inside the wire spirals with a filling material. This can be done by winding the wire around the wire-like filling material already at the stage of manufacturing the spiral, or alternatively either by inserting relatively rigid strips into the interior of the wire spirals or by drawing relatively soft yarns into said spaces. Pulling is best done with a hook into which wire 2 67898 is threaded twice. Rigid strips, on the other hand, are obtained inside the wire spirals simply by feeding the strip between two rolls, whereby the strip threads itself through the spiral.

5 Rigid filling strips may have different cross-sections, but they are all characterized by the preservation of the original shape. Such filler strips are arranged between adjacent interleaved threaded portions projecting from opposite sides into a wire spiral so that the longitudinal full edges of the strip at most lightly contact the folds of these threaded portions. In order for the filling tape to be insertable into the wire spiral, the tape must fit quite loosely inside the spiral to avoid excessive insertion friction. As a result, the filling strip can substantially cover only the part of the free interior of the wire spiral 15 which is located between the folds of the opposite threaded parts. With the known filling strips, the permeability of the wire can be reduced 3 2 to a value of about 7000 m / m h.

With soft filling wires, the air permeability of the spiral wire can be reduced to a maximum of 3000 m / m h.

However, it is often necessary to seal the wire either to the full width or at least from the edges to a value of less than 3000 m / m h. In addition, it is difficult to reduce the permeability of the wire in practice, because the filling yarns have to be pulled separately by a hook through the wire spiral, which requires separate equipment and makes the filling operation slow.

The object of the present invention is to provide a spiral wire which avoids the above-mentioned disadvantages and which makes it possible to achieve a remarkably low air permeability with simple filling strips. This object is achieved by a spiral wire according to the invention, characterized in that - the filling elements are in the form of strips in which the distance between the longitudinal edges of the strip corners between the threaded parts.

The invention is based on the idea that a strip is used as the filling material, which has a cross-sectional shape such that the strip flattens and widens when the wire is subjected to thermal stretching of the so-called wire. fikseerauk-Sessa. Thus, the strip can be shaped so that it can be inserted relatively loosely and easily into the wire spiral, but after flattening, it spreads from the edge of the thread to the edge inside the thread spiral and thus seals the interior of the wire spiral more widely than has been possible with filler tape. The heat treatment of the wire, in which the connected wire coils are stretched by heat, is a normal operation for all drying fabrics to fix the wire to the final customer size.

With the spiral wire according to the invention, air permeability values of 500-1000 m / m h can be achieved.

The invention also relates to a method for producing a spiral wire as described above, and this method is characterized by what is set forth in claim 9.

The method is rapid because it does not require any separate equipment to pull the filler strips into the wire spirals 25, but the strips can simply be inserted into the spirals at the same time as the spiral wire is made and the same technique used to feed the spiral binder wires into the wire.

The invention will be described in more detail below with reference to the accompanying drawing, in which Figure 1 shows a top view of a portion of a spiral wire, Figures 2 and 3 show a larger side view of the wire before and after thermal stretching of the wire, and Figures 4-6 show alternative profile strip profiles.

4 67898

The helical wire shown in Fig. 1 of the drawing consists of a plurality of transverse wire spirals 1 arranged side by side in the longitudinal direction of the wire so that the threads 2 of the adjacent spirals extend interleaved centrally. A transverse tie wire 3 is threaded through the interleaved parts 2a of the paired wire spirals, which acts as an interconnecting articulated shaft between the spirals. The helical wire further comprises filling strips 5 inserted into the free interiors 4 of the wire spirals.

The filling strip 5 has a V-shaped cross-sectional shape in the embodiment shown in Figures 2 and 3. The shape of the filling strip is designed so that the distance A between the longitudinal edges 5a of the strip, FIG. 2, increases to B, FIG. 3, when the strip is flattened against the plane 15 passing through the longitudinal edges in a direction perpendicular to C.

Such flattening is effected in the strip when the wire is stretched by heat to fix the wire, whereby the initially circular threads of the spirals become flat in shape as shown in Figures 2 and 3.

The material of the filling strip is then chosen such that the strip has a mechanically rigid basic shape, which, however, is able to deform when the shape of the spiral changes under thermal stretching and to open when compressed by the spiral. The material may be plastic, either thermoplastic, in which case the heat is softened, or thermoset, in which case only mechanical compression molding the material. The filler tape may also be relatively hard rubber or metal.

When the filler tape is flattened in the thermal stretching of the wire and the longitudinal edges of the tape are spaced apart, the longitudinal edges 30 protrude below the threaded interleaved portions 2a, i.e. at the corners between the threaded interleaved portions 6. The strip thus effectively blocks the spiral openness. To facilitate this, the longitudinal edges 5a of the strip are preferably tapered towards the tip.

Figures 4-6 show filling strips 15, 25 and 35 according to alternative embodiments, all of which have

II

5 67898 is characterized in that the distance between their longitudinal edges increases as the strip is flattened.

Example

A wire was made with 225 wire spirals per 5 meters. The spirals were made of 0.7 mm diameter polyester yarn and the binding yarns were 0.9 mm diameter polyester yarns.

In making the wire, the filler tapes of Figure 2 made of a rigid 0.2 mm polyester tape were loosely fed into the spirals.

The wire was stretched to 20% of its original length at 190 ° C. At that time, the spirals stretched so much that their number decreased to 190 spirals per meter. As a result of the deformation of the spirals, the filler strips 15 flattened so much that their longitudinal edges protruded tightly under the interlaced parts of the spirals.

The heat treatment is selected so that the heat is in the softening temperature range of the filler material used, e.g. polyester 180-200 ° C and polyamide 160-170 ° C.

The drawing and the related explanation are only intended to illustrate the idea of the invention. The details of the spiral wire according to the invention and the method for its production can vary considerably within the scope of the claims. The filler strips may also be a bicomponent material whose components expand differently in heat. This different thermal expansion component of the components can be utilized to effect the flattening of the filling strip, i.e. the deformation required by the invention, by means of heat, so that the filling material blocks the interiors of the spirals as effectively as possible. It is also possible to use a perforated filler strip if it is desired to adjust the permeability of the wire to a value between the low permeability of the fully open 3a. The filler strips may extend across the entire wire or only over a defined area thereof, e.g., both edge-35 areas. The spiral wire may also be designed for use as a filter or transport wire.

Claims (10)

A spiral wire, in particular a paper machine drying wire, which wire consists of transverse yarn spirals (1) arranged side by side in the longitudinal direction of the 5th wire, the threads (2) of adjacent spirals interleaved with each other, - 10 yarns (3), and - filler members (5) located in the free interior (4) of the yarn spirals for limiting the air permeability of the wire, characterized in that the filler members are in the form of a strip and (5) in which the longitudinal edges (5a) of the strip ) increases as the strip flattens against the plane of the longitudinal edges in the transverse direction, and - that the longitudinal edges (5a) of the strip (5) press against the corners (6) between the 20 interlaced threaded parts (2a). Spiral wire according to Claim 1, characterized in that the filling strip (5) contacts the thread (2) of the wire spiral (1) at at least three points. Spiral wire according to Claim 2, characterized in that the filling strip (5) has a U-, V-, M- or similar open profile shape. Spiral wire according to Claim 2 or 3, characterized in that the filling strip (5) has a cross-sectional shape such that it flattens under the effect of mechanical compression or compression and heat. Spiral wire according to Claim 2 or 3, characterized in that the filling strip (5) is a bicomponent material whose components have different thermal expansions and has a cross-sectional shape such that it flattens under the effect of heat. 7 67898 Spiral wire according to one of the preceding claims, characterized in that the longitudinal edges (5a) of the filling strip (5) are sharp. 6 67898 Spiral wire 5 according to one of the preceding claims, characterized in that the length of the filling strips (5) is less than the length of the interior (4) of the wire spiral (1). A method for producing a helical wire, in particular a drying machine for a paper machine, according to which - a plurality of wire spirals (1) are arranged side by side so that the threads (2) of adjacent spirals overlap, - through interlocking spiral portions (2a) of paired wire spirals the bonding yarn (3), - the yarn spirals are stretched under heat in the transverse direction in the plane of the bonding yarns to make the helical threads (2) flat, and - a filling material (5) is fitted to the free interiors (4) of the yarn spirals (4) before stretching, inserting a filling strip (5) in the shape of which the distance (A) between the longitudinal edges (5a) increases as the strip is flattened against the plane of the longitudinal edges in the transverse direction, and - the filling strips (5) are flattened by thermal spiral stretching the longitudinal edges (5a) of each filling strip protrude into the interleaved threads to the intermediate corners (6) of the rows (2a). Method according to Claim 8, characterized in that the filling strips (5) are flattened by means of mechanical compression provided by the wire spirals (1). Method according to Claim 8, characterized in that the filling strips (5) are flattened by means of the heat generated in the thermal stretching of the wire spirals (1). 67898 8