EP0116894B1 - Method for manufacturing a link belt made of spiral elements - Google Patents

Abstract

Double helices each comprising two helix elements made from plastic wire with the longitudinal axes of the two helix elements extending in parallel and with the windings of the two helix elements intertwined, the double helices being formed by winding two plastic wires in parallel and without twist on a mandrel and being used to assemble a spiral belt by interengaging in zipper fashion a multiplicity of helices via meshing the windings of one helix with the windings of the next helix, and by inserting a pintle wire into the passage formed by the overlapping windings.

Description

The invention relates to a method for producing a spiral tape, in which the spiral elements are partially engaged with each other in the manner of a zipper and are secured by a plug-in wire, and in part the turns of the spiral elements loop around one another, the spiral elements being produced by winding two wires onto a mandrel, the coiled spirals are mutually offset perpendicular to their longitudinal axis and then the one of the two spiral elements with a preceding spiral and the other with a subsequent spiral zipper-like engagement and connected by inserting a plug wire.

Spiral belts are used for transport purposes and as paper machine clothing. The manufacturing cost of spiral tapes is heavily influenced by the manufacturing cost of spirals, and likewise the manufacturing capacity for spiral tapes depends primarily on the spiral production. The production capacity of a machine which assembles the spirals into a spiral band is generally so great that a very large number of spiral production machines which run at top speed are required in order to utilize a system for further processing the spirals into a spiral band. It is therefore important to keep the manufacturing costs of the spirals as low as possible and to increase the output of a single spiral machine as much as possible.

An increase in capacity of the spiral manufacturing machines can be achieved by winding double spirals instead of spiral elements. A double spiral and a method for its production is known from DE-B 3003344. With this method, the two spiral elements of the double spiral can be easily separated by pulling them apart after manufacture. This is achieved by a complicated process in which the two wires wound on the winding mandrel alternately cross each other. As a result of these crossings, however, the spirals have an asymmetrical cross-sectional shape, which makes them unsuitable for producing spiral strips with a smooth surface. It is also not specified how these spirals can be processed into a sieve belt.

Double spirals are also known from EP-A 18200. However, the double spirals are used in a spiral band without lateral displacement, i.e. with overlapping longitudinal axes.

Spiral tapes made from a large number of spirals, the turns of the individual spirals wrapping around one another, are known from DE-C 54525, 77 147 and 80763, and additional plug-in wires can be inserted between the wrapping bindings. The manufacture of these spiral bands is screwed. Such spiral tapes are, however, much more complex to manufacture than e.g. spiral tapes known from DE-A 2 938 221, in which the spirals are inserted into one another perpendicular to the longitudinal axis and secured by plug-in wires.

The object of the invention is to simplify the production of a spiral link belt and in particular to reduce the cost share of spiral production in the total costs of a spiral belt.

This object is achieved in a method of the type mentioned at the outset in that the winding of the two wires onto the mandrel is carried out by parallel application of these wires to the mandrel, so that the turns of the spiral elements produced in this way loop around each other to form a double spiral and the two Spiral elements are secured in the staggered state.

Preferred embodiments of the invention are the subject of the dependent claims.

The advantages which can be achieved by the invention consist in particular in increasing the capacity of the spiral winding machines, the previous spiral winding machines being able to be converted in a simple manner to the production of double spirals.

In the manufacture of the double spiral, the two plastic wires are preferably wound tightly, so that each spiral element has a pitch equal to twice the diameter of the plastic wire.

During the further processing of the double spiral to form a spiral band, the two spiral elements of a double spiral are offset relative to one another perpendicular to their longitudinal axis, so that their turns wind around each other. Without additional measures, the two spiral elements would immediately slide back into a double spiral. The offset of the spiral elements against each other must therefore be ensured. This is preferably done by applying an adhesive strip to the offset spiral elements.

The spiral elements can be offset against one another in such a way that the spirals are guided over two wires which are located within the cavities of the spiral elements. So that the wires are not carried along by the spirals, they have a curved shape, e.g. U shape. By means of rollers acting on the outside of the spirals, in particular in the concave regions of the curvatures, it is thereby achieved that the wires cannot be carried along by the spiral elements moving further, but slide inside their cavities. Before the spiral elements leave the wires, the adhesive tape is applied.

The two coherent spiral elements are joined together with other such spirals to form a screen belt Lichen way in which the turns are inserted and a plug wire is inserted through the channel formed. The sieve belt is then heat-set as in DE-A 2 938 221. The temperature and the tension exerted on the sieve belt are selected so that the turns of the spirals penetrate somewhat into the material of the plug wires and thereby deform them in a wave shape. The spirals lie closely together without tension spring tension, so that the wavelength of the wavy plug wire is approximately equal to twice the diameter of the plastic wire of the spirals.

With such a spiral belt, openings of different sizes result, which can be disruptive when used as a covering for the paper machines. This disadvantage can largely be eliminated by inserting a plug wire between the wrapping turns of the spiral elements of a double spiral. Since the turns of the spiral elements on this plug wire engage at the same point in the longitudinal direction of the plug wire and only on opposite sides, this plug wire is not deformed in a wave shape during the heat setting.

• Fig. 1 eine Spirale nach dem Stand der Technik;
• Fig. 2 eine aus zwei Spiralelementen bestehende Doppelspirale;
• Fig. 3 eine Doppelspirale mit zwei gegeneinander versetzten Spiralelementen;
• Fig. 4 ein Gerät zum Versetzen der beiden Spiralelemente einer Doppelspirale gegeneinander;
• Fig. 5 im Schnitt die beiden über Drähte laufenden Spiralelemente von Fig. 4 und
• Fig. 6 und 7 Spiralbänder aus Doppelspiralen.

Exemplary embodiments of the invention are explained in more detail below with reference to the drawing. Show it:

• Figure 1 shows a spiral according to the prior art.
• 2 shows a double spiral consisting of two spiral elements;
• 3 shows a double spiral with two mutually offset spiral elements;
• 4 shows a device for displacing the two spiral elements of a double spiral relative to one another;
• Fig. 5 in section the two spiral elements of Fig. 4 and running over wires
• 6 and 7 spiral bands made of double spirals.

Fig. 1 shows a spiral according to the prior art. The gradient of the spiral is shown larger than it actually is for the spirals used for the production of a screen belt. The spirals usually have a pitch equal to the wire diameter up to a maximum of twice the wire diameter.

Fig. 2 shows a double spiral 3, which consists of two intertwined spiral elements 1, 2. In the spirals shown in FIGS. 1 and 2, the winding spacing is the same. In the case of the double spiral, each spiral element 1 or 2 per se has a double slope and the slope angle is also correspondingly larger. As a result, double spirals cannot be combined into a spiral band in the same way as single spirals. Because of the larger pitch angle of the turns, the double spirals that are joined together immediately push apart, i.e. separate spontaneously and do not allow the insertion of a plug wire. Double spirals would have to be held together with suitable means so that a plug-in wire can be inserted. However, this would complicate the manufacturing process for the spiral belt in such a way that the cost reduction gained by increasing the capacity of the spiral machines would be lost again. It should be taken into account here that a double spiral would first have to be pulled apart so that there is a distance between the turns that is at least equal to the wire diameter, so that each spiral element 1, 2 would have a pitch equal to four times the wire diameter.

Fig. 3 shows a double spiral 3, in which the two spiral elements 1 and 2 are offset from each other, so that their windings loop around each other. Two such double spirals can be inserted into one another, since each of the offset spiral elements 1 or 2 has only one pitch equal to twice the wire diameter. During manufacture, the double spiral can thus be wound without a turn spacing, i.e. turn after turn. However, there is the problem that the two spiral elements 1, 2 immediately slide together again, i.e. assume the position shown in Fig. 2, in which the longitudinal axes of the spiral elements 1, 2 coincide when the forces displacing the spiral elements laterally are canceled.

Fig. 4 shows a device for laterally displacing the spiral elements 1, 2 and for securing this displacement. The device has a roller 11 and a pair of rollers 12 which are driven at the same peripheral speed. Around the roller 11 and through the gap of the roller pair 12, two U-shaped, rigid wires 13 are placed. Each spiral element 1 or 2 runs onto one of the two wires 13 in such a way that the spiral elements 1, 2 are pulled apart perpendicularly to their longitudinal axis and thus two spiral elements with winding turns are obtained. This process is comparable to the process described in DE-A 3 220 517. The spiral elements are driven by means of the roller 11 and pushed over the U-shaped wires 13. The arrangement of the rollers and the shape of the wires 13 are such that the wires 13 cannot be carried along by the spirals being conveyed on.

FIG. 5 shows a section through the offset spiral elements 1, 2 running on the wires 13. The shape and dimensions of the cross section of the wires are adapted to the free cavity within the connected spiral elements.

In this laterally offset state, an adhesive tape 14 is fed into the nip of the pair of rollers 12 and applied to the two spiral elements 1, 2. The adhesive tape 14 prevents the spiral elements 1, 2 from sliding together again. The spiral elements provided with the adhesive tape are now placed in a jug and can slide in the same without any difficulty Chen how simple spirals are put together to a sieve belt. After joining and inserting the plug wires, the adhesive tape can be removed again.

The device for laterally displacing and securing the displacement of the spiral elements is simple in construction and allows a high working speed, so that the double spirals produced by approximately ten spiral winding machines can be processed with a single device of this type. Removing the adhesive tape is also easy and does not involve any significant costs.

Fig. 6 shows a section of a spiral band, which is made of double spirals with offset spiral elements. The turns of a spiral element of a double spiral are inserted between the turns of a spiral element of the following double spiral and a plug wire 6 is pushed through the channel formed in the overlap region of the turns of the two spiral elements. Because of the different sizes of the openings remaining between the spiral elements, the permeability of the spiral band shown in FIG. 6 is not uniform. It can therefore sometimes be expedient to insert additional plug wires 7 between the mutually wrapping turns of the spiral elements 1, a double spiral. This significantly improves the uniformity of the permeability of the spiral band.

Claims (3)

1. Method of producing a spiral belt in which spiral elements (1, 2) are partly engaged with each other in zipper fashion and are secured by a pintle wire (6, 7) and the windings of the spiral elements (1, 2) are partly intertwined, the spiral elements (1, 2) being produced by winding two wires onto a mandrel, the spirals wound together being mutally offset perpendicularly to their longitudinal axis and then one of the two spiral elements (1, 2) being engaged with'a preceding spiral and the other spiral element engaged with a succeeding spiral in zipper-like fashion and connected by inserting a pintle wire (6, 7), characterized in that the winding of the two wires onto the mandrel is effected by parallel application of those wires onto the mandrel so that the windings of the thus produced spiral elements are intertwined forming a double spiral (3) and in that the two spiral elements (1, 2) are secured in the mutually offset state.

2. Method according to claim 1, characterized in that the two spiral elements (1, 2) are mutually offset by pushing each of the spiral elements (1, 2) onto a piece of wire (13).

3. Method according to claim 1 or 2, characterized in that the mutually offset spiral elements (1, 2) are secured in their offset state by application of an adhesive tape (14).

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