GB2083431A - Link belts - Google Patents

Abstract

A link belt structure formed from interdigitated coils (11) joined by hinge wires (12) is provided with tape- like elements (13) within the individual coils to reduce the permeability of the total structure and/ or to introduce some requisite character therein appropriate to the nature of the elements and their relationship to the coils within which the same are located. <IMAGE>

Description

SPECIFICATION Link belts The invention concerns link belts, and has more particular reference to link belts of the kind comprising a multiplicity of helical coils of a thermoplastic material arranged in adjacent interdigitated disposition.

A link belt of this general kind is disclosed in German Auslegeschrift No. 24 19 751, whilst an improved form thereof is the subject matter of British Patent Application No. 8015965 (20511 54A).

The link belts as aforesaid, the adjacent coils of such belts usually being connected together by means of hinge wires engaged with the interdigitated turns thereof, are thought to have application as support structures in the context of papermaking and like machines. However, the extent of their application in this context is believed to be limited having regard to the high degree of permeability of the belt, the inherent permeability of the belt per se substantially exceeding that required for some papermachine dryer fabric applications and rendering the belt per se unsuitable for these applications.

It has been proposed to reduce the permeability of a link belt by introducing yarns into the space within a given coil and between the opposing bights of the coils existing at either side of the given coil and interdigitated therewith, but this proposal has proved unsatisfactory in that difficulty is experienced in locating a sufficient mass of yarn within the space and throughout the full axial extent thereof materially to affect permeability.

The object of the invention is to provide a link fabric structure having a substantially lesser permeability than the inherent permeability of the link belt per se and of a weight per unit area not substantially different from that of such link belt per se.

According to the present invention there is proposed a link belt structure comprising a multiplicity of helical coils of a thermoplastic material arranged in interdigitated side-by-side disposition to define a link belt, characterised by a strip or strips of a tape-like material arranged in some at least of the respective spaces within each coil and existing between the opposed bights of those coils at either side thereof and arranged in interdigitated disposition therewith and the inside of the said coil.

According to a preferred feature, the coils are of flattened form, the minor internal dimension thereof being less than the space between opposing bights of respective coils engaged with a given coil at each side thereof.

According to a further preferred feature, the or each strip is of a width at least equal to the internal dimension of the coil measured in a direction perpendicular to the plane of the said structure.

Preferably the or each strip is of a width approximating to but less than the spacing between the opposed bights.

According to a still further preferred feature, the tape has a reflective surface at one face at least thereof.

Typical tape-like strips comprise the reflective strip aforesaid, a monofilament polyester or other yarn of flat form wherein the width/thickness ratio is of the order of 2 or more to 1, or a split film tape wherein the width/thickness ratio is approximately 75 :1. The tape may be wholly impermeable or may be of braided form and hence of limited permeability.

The invention will now be described further, by way of example only, with reference to the accompanying drawings illustrating two embodiments thereof and in which: Fig. 1 is a plan view of a link belt structure embodying the invention; Fig. 2 is a sectional view of the structure of Fig. 1, drawn to a larger scale; and Fig. 3 is an end elevation of a part of the link belt structure of Fig. 1, drawn to a larger scale.

Referring now to the drawings, a link belt comprises a multiplicity of individual, helical coils 11 arranged in interdigitated side-by-side disposition and connected together by respective hinge wires 12 threaded through the interdigitated turns of adjacent coils. The coils 11 are of a synthetic thermoplastic monofilament material, as too are the hinge wires 12, and the link belt as thus far described is produced in accordance with the teaching of the specification of British Patent Application No. 8015965 (20511 54A) to which reference is directed for further detail.

As provided for by the present invention each coil of the link belt as aforesaid includes a respective moisture impermeable tape-like element 13, the tape-like element 1 3 being located in that space 14 within a given coil existing between the opposed bights 1 5, 16 of the turns of the coils existing at either side of the given coil and engaged therewith. The longitudinal edges of the link belt are sealed to hold the strips in the respective coils.

In a typical example, the coils are produced from a monofilament yarn having a diameter of 0.7 mm and the major and minor dimensions of the flattened interior form of the coil are respectively 6 mm and 1 mm. The tape-like element 13 comprises a metallised plastics film strip approximately 3 mm wide.

In the particular example under consideration, at least one side of the tape is metallised, but the surface characteristics of the strip will be determined having regard to the specific requirements of the context in which the link belt structure, that is to say the link belt per se and the tape-like elements applied thereto, is to be used, be it in the field of paper-machine clothing or otherwise. The thickness of the strip is not thought to be in any way critical, subject to the proviso that the strength thereof is adequate to enable satisfactory introduction of the strip into the space as by drawing a length, say 10 metres, of the same longitudinally of the coil.

Indications are that, by means of the tape-like elements as herein proposed, we are able to reduce the permeability of the link belt as measured on a Frazier Standard Air Permeability Testing Machine from, say 16000 cubic metres per square meter per hour at 100 pascals pressure difference to, say, 3200 cubic metres per square metre per hour at the same difference, and thereby provide a structure of a permeability appropriate to that of a dryer fabric for a presentday high speed newsprint machine.

Conveniently, the tape-like element is of a width in excess of the minor dimension of the coil and approximating to the separation of the bights 15, 16, the tape being entered flat as shown in Fig. 3 of the drawings and extending in continuous form throughout the full axial extent of the coil.

Whilst generally, the width of the strip will be at least 1.25 times the minor internal dimension of the coil, it may be found convenient, in some instances, for the strip to be of a width approximating to the minor internal dimension of the coil and for the strip to be twisted slightly about the longitudinal axis thereof. If desired, sideby-side strips may be provided in each space. As an alternative to having the strip (or strips) extend continuously throughout the full axial extent of each coil, short strips of a length substantially less than the full axial extent of the coil may be provided in spaced end-to-end disposition within the coil, or strips (or pluralities thereof) may be provided in respect of some only of the coils.

The invention is not limited in its application to coils of the flattened form shown in Fig. 3, and may be applied to the context of coils of circular or oval transverse cross-section, the strips conveniently being of a width to extend in contact with the inner surface of the coil with the longitudinal edges thereof in contact with the surface of the respective bights where the same cross the coil inner surface.

It is to be observed that, by providing the strip in the form of a coloured element, thereby to render a hue to the fabric, a permeability colourcode characteristic can be introduced. In an alternative arrangement the strips are of such cross-sectional dimension as to be capable of movement, whether as translational or pivotal motion, in the direction of the minor internal dimension of the coils, such movement being used to control the flow of air through the fabric.

Claims (12)

1. A link belt structure comprising a multiplicity of helical coils of a thermoplastic material arranged in interdigitated side-by-side disposition to define a link belt, characterised by a strip or strips of a tape-like material arranged in some at least of the respective spaces within each coil and existing between the opposed bights of those coils at either side thereof and arranged in interdigitated disposition therewith and the inside of the said coil.

2. A link belt structure as claimed in claim 1, wherein the coils are of flattened form, the minor internal dimension thereof being less than the space between opposing bights of respective coils engaged with a given coil at each side thereof.

3. A link belt structure as claimed in claim 1 or 2, wherein the or each strip is of a width at least equal to the internal dimension of the coil measured in a direction perpendicular to the plane of the said structure.

4. A link belt structure as claimed in claim 3, wherein the or each strip is of a width equal to at least 1.25 times the said internal dimension of the coil.

5. A link belt structure as claimed in any one of the preceding claims, wherein the or each strip is of a width approximating to the spacing between the opposed bights.

6. A link belt structure as claimed in any one of the preceding claims, wherein a single strip only is provided in a respective coil.

7. A link belt structure as claimed in any one of the preceding claims, wherein at least one strip is provided in each respective coil.

8. A link belt structure as claimed in any one of the preceding claims, wherein the strip or strips provided in a respective coil extend or collectively extend throughout the full longitudinal extent of such coil.

9. A link belt structure as claimed in any one of the preceding claims, wherein each strip is impermeable to moisture.

10. A link belt structure as claimed in any one of the preceding claims, wherein each strip is metallised to provide a reflective characteristic thereto.

11. A link belt structure as claimed in any one of the preceding claims, wherein the width/thickness ratio of each strip lies within the rangeof2:1 to 75:1.

12. A link belt structure substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.