WO2000005449A2

WO2000005449A2 - Belt jointing apparatus

Info

Publication number: WO2000005449A2
Application number: PCT/GB1999/002321
Authority: WO
Inventors: Nevin John Black
Original assignee: Scapa Group Ltd; Madison Filter 981 Ltd
Current assignee: Scapa Group Ltd; Madison Filter 981 Ltd
Priority date: 1998-07-21
Filing date: 1999-07-19
Publication date: 2000-02-03
Anticipated expiration: 2001-01-21
Also published as: AU5051899A; WO2000005449A3; GB9815719D0

Abstract

A belt (10) has ends (11, 12) upon each of which are secured edge strips (19, 13) having female connectors (23) for receiving male connector elements (26, 27) on the longitudinal edges of a connector strip (25). The connectors are joined by sliding the connector strip longitudinally into the female connectors, and the male connectors may be barbed to cooperate with corresponding lips of the female connectors to prevent pulling apart of the connectors in the machine direction. The male connectors may be in the form of solid beads, to be received in hollow beads forming the female connectors, which may be double-lobed, and the connector strip may be formed on its opposite edges with a male and a female connector for connection with a female and a male connector on the edge strips.

Description

BELT JOINTING APPARATUS

This invention relates to apparatus for jointing belts, particularly for

forming belts such as filter belts into endless bands. The term 'belts'

includes filter belts for belt filter presses, horizontal belt filters and vacuum

drum filters, and may also extend to papermaking fabrics.

Filter belts may be made from fabrics including woven, needlefelt and

spiral link structures, and most commonly woven structures of e.g. single

or double layer design, comprising polyester or polypropylene monofilament

or multifilament yarns. Examples of such fabrics are disclosed in EP-A-

0 273 892 and US 5,244,543.

It is not practical to use endless woven filter belts due to their great

length and the non-cantilevered construction of the machinery on which the

belts are used. This makes the fitting of a endless belt extremely difficult

or impossible. Consequently, filter belts for such machinery need to be

woven flat and provided with a seam construction to render the belts

endless when fitting onto the machine.

The most commonly employed technique is to use a so-called clipper

seam, which comprises a large number of metal hooks which are pressed

into each end of the fabric and held in place by adhesive. A pintle wire is

inserted into the tunnel formed by the interdigitated loops formed by the

hooks to form an endless fabric. In a modified version of this method,

hooks are pressed into strips of canvas cloth which are glued or stitched to the edges of the fabric, and the hooks are interdigitated and joined by a

pintle wire as before.

An example of a clipper seam is described in US 4,344,209, in

relation to a papermachine dryer fabric.

Despite being quick and simple to produce and join together, clipper

seams have several disadvantages. The metal hooks are susceptible to

corrosion and rust, and driving hooks into the fabric damages the yarns.

The proudness of the hooks, protruding beyond the fabric surface planes on

both sides causes the loops of the hooks to abrade against scrapers or

rollers in the machinery of the filter apparatus. Being of rigid metal, the

hooks are inflexible, and this creates problems in guiding the fabric seam

around rollers and the flexing of the fabric relative to the hooks causes wear

in the seam region which is usually the main reason for belt failure. In

filtration of high value substances, there is also the problem of loss of solids

through the large voids between the interdigitated hooks.

Spiral link fabrics, e.g. as disclosed in GB-A-2,051 , 154 can be used

without a clipper seam, but the only feasible spiral material which is not

prohibitively expensive is polyester, which is unsuitable for use in

applications where the filter belt is compacted, as in belt filter presses. It

can also be difficult and cumbersome to reduce the large open area of the

spiral link structure using stuffer yarns or expansible yarns for example,

which also add to the material cost of the belt. A recent development has been to use pin seams in woven fabrics,

which are prepared similarly to these used in papermaking fabrics, as set

out for example in GB-A-1 ,488,815. However these seams are extremely

laborious and time consuming to prepare, and they are thus very expensive.

The joining of pin seam loops can be a very difficult and time consuming

task.

An object of the present invention is to provide a belt jointing

apparatus which can substantially overcome at least some of the problems

of known jointing apparatus set out above.

According to the present invention, therefore, belt jointing apparatus

comprises an elongate male or female edge connector member extending

along each belt edge to be joined, and an elongate strip member, having

female of male connectors matching the edge connector members provided

on the belt edges.

The strip member may be adapted for connecting the edge connector

members by being slidingly inserted into engagement therewith from one

end, or preferably for easy insertion of the male members into the female

members, but for example barbed in cross-section to prevent unwanted

withdrawal after insertion.

The edge connector members may be in the form of strips attached

to the respective edges of the fabric by stitching, welding or adhesive, and

may be of semi-hard plastics or material or synthetic rubber. The elongate strip member may be of semi-hard plastics or natural or

synthetic rubber, or of a suitable metal, such as steel.

The top and/or bottom surfaces of the male and female edge

connections may be flush with the corresponding top and/or bottom surface

of the elongate strip.

In one embodiment, the edge connector members may be formed

with a hollow cylindrical bead, with a slot, so that the walls of the bead

form relatively flexible lips, and the strip member has rigid solid edge beads

which can be pushed into the hollow beads on the edge connector

members.

In another embodiment, the strip member may be formed with

barbed, for example arrow-shaped cross-sectional formations along each

side which can be inserted into correspondingly shaped grooves in the

exposed ends of the edge connector members, including lips for

engagement with the barbs.

The connections can be heterogenous, that is with different shaped

male and female elements, or one edge connector may have a male

connector and the other a female connector, the strip member being

provided with a corresponding female connector on one edge and a male

connector on the other edge.

To assist with longitudinal insertion of the strip member, the hollow

beads may be formed as double lobed hollow beads, with one lobe being sufficiently larger than the solid beads to allow easy movement

longitudinally thereof, and the other lobe providing a snug fit about the solid

bead. Preferably, the larger lobe is an inner lobe and the snug fitting lobe

is an outer lobe, so that on completion of insertion, tension on the belt may

draw the solid bead into the snug fitting lobe.

The edge connectors and/or the strip member may be perforated if

desired, but an impermeable structure is preferred to prevent loss of

vacuum and leakage of product. Making the connectors impermeable also

eliminates the need for cloth flaps to cover the seam region.

The invention will now be further described by way of example with

reference to the accompanying drawings, which show some examples of

embodiments of the invention.

In the drawings:-

Figure 1 is a machine-direction cross-sectional view of a belt jointing

apparatus according to the invention wherein barbed

connections are used;

Figure 2 is a machine-direction cross-sectional view of a belt jointing

apparatus according to the invention wherein bead and slotted

channel connectors are used;

Figure 3 is a machine-direction cross-sectional view of a belt jointing

apparatus similar to Fig. 2 but with heterogenous connectors;

and Figure 4 is a machine-direction cross-sectional view of a belt jointing

apparatus of the invention which is a variant on the Figure 2

embodiment.

Referring to Fig. 1 , a filter belt 10 has ends 1 1 , 12 which can be

brought close together for joining the belt into an endless loop, in situ after

mounting the belt on a filtration machine.

End 1 1 of the belt has an edge connector member 13 secured along

the edge, laterally across the machine width. This member 13 comprises

a body having two flaps 14, 15 between which the end 1 1 of the belt is

received. The edge connector member 13 is secured to the belt by use of

stitching, welding or adhesive to attach the flaps 14, 15 to the end 1 1 . The

edge connector member 13 has a wider exposed end 16 with an end face

provided with a slot 17, with flaps 18 which define an inwardly directed

arrow shaped cross section for the slot 17.

End 12 of the belt has an edge connector member 19 secured there

along which is congruent with the member 13 described above. It has flaps

20, 21 secured to the belt end 12, a wider exposed end 22, and a slot 23,

with flaps 24 which define an inwardly directed arrow shaped cross section

for slot 23.

The edge connector members 13, 19 are joined by a strip member

25, having its edges formed into arrow shaped cross section barbs 26, 27.

The members 13, 19 are joined either by pushing the strip member 25 into the slots 17, 23 from one end, or causing the barbs 26, 27 to enter the

slots 17, 23 to be retained against pulling out by the flaps 18, 24 depending

upon the relative flexibility or hardness of the members and strip.

In Fig. 2, filter belt 30 has ends 31 , 32 which can be brought close

together to be joined into an endless loop. Edge connector members 33, 34

are connected to the ends of the belt as in Fig. 1 above. Each end of the

edge connector members however comprises a hollow tubular bead 35,

with a slot 36, 37 in the exposed end. A strip member 38 has cylindrical

beads 39, 40 which are received in the tubular beads 35, 36 of the edge

connector members 33, 34 by being pushed into the beads 35, 36 from one

end.

Fig. 3 shows a variant of Fig. 3, wherein one edge member 41 has

a hollow tubular bead 42, and the other 43 has a cylindrical solid bead 44.

A strip member 45 is provided having a solid bead 46 along one edge, and

a tubular bead 47 along the other edge, for engagement with the respective

tubular bead 42 and solid bead 44 of the edge members 41 and 43.

The edge connector members are mounted on the ends 48, 49 of

filter belt 50 in the same way as in Figs 1 and 2.

Fig. 4 shows a further variant on the Figure 2 embodiment wherein

each edge member 51 , 52 mounted on the ends 53, 54 of a filter belt 55

are connected by a strip member 56 having solid edge beads 57, 58 which

are received in respective two-lobed or hourglass-sectioned hollow tubular beads 59, 60, one formed integrally with each of the edge members 51 , 52

respectively. The inner lobe 59a, 60a of each hollow bead 59, 60 is of

larger diameter than the outer lobe 59b, 60b the former being at least

sufficiently larger than the bead 57, 58 on the connector strip 56 to allow

free movement of the bead in the inner lobe, whilst the outer lobe is of a

diameter to snugly fit the head 57, 58. This allows the connector strip 56

to be easily inserted by feeding the strip 56 with its beads 57, 58 in the

larger inner lobes of the edge members as shown in Figure 4. When fully

inserted, due to tension on the belt 55, the beads 57, 58 are pulled into the

snugly fitting lobes 59b, 60b to hold the connector 56 firmly in position.

The edge connector members in each embodiment may be made of

natural or synthetic rubber, thermoplastic material, thermoset resin or steel,

as may be respective strip members.

Specific materials include Santoprene, Thermoplast K, polypropylene

and nylon. The materials may have hardnesses of between 60 and 70 on

the Shore A scale.

The female connectors may be more flexible than the male

connectors if desired.

Claims

1 . Belt jointing apparatus comprising an elongate male or female edge

connector member extending along each belt edge to be joined and

an elongate strip member having female or male connectors matching

the edge connector members provided on the belt edges.

2. Belt jointing apparatus according to claim 1 wherein the strip member

is adapted to connect the edge connector members by being slidingly

inserted into engagement therewith from one end.

3. Belt jointing apparatus according to claim 2 wherein the male

members are barbed in cross-section for easy insertion into the

female members yet to prevent unwanted withdrawal in the running

direction of the belt, after insertion.

4. Belt jointing apparatus according to claim 1 wherein the edge

connector members comprise strips attached to the respective belt

ends.

5. Belt jointing apparatus according to claim 4 wherein the edge

connector members and the elongate strip member are of semi-hard

plastics material, natural or synthetic rubber or a suitable metal.

6. Belt jointing apparatus according to claim 1 wherein said female

connector members each comprise a hollow cylindrical bead with a

slot, so that walls of the bead form relatively flexible lips, and the

male connector members comprise rigid solid edge beads which can be pushed into the hollow beads.

7. Belt jointing apparatus according to claim 1 wherein said male

connector members comprise barbed arrow-shaped cross-sectional

formations along each respective edge and said female connector

members comprise correspondingly shaped grooves, including lips for

engagement behind the barbs.

8. Belt jointing apparatus according to claim 6 or 7 wherein said male

connector members are provided on said elongate strip member, and

said female connector members are provided on said edge connector

members.

9. Belt jointing apparatus according to claim 6 or 7 wherein one edge

connector member has a male connector member and the other a

female connector member, and said elongate strip member has a

female connector member along one edge and a male connector

member along the other edge.

10. Belt jointing apparatus according to claim 6 wherein said female

connector members each comprise double-lobed hollow beads, with

one lobe sufficiently larger than the male connector beads to allow

easy longitudinal movement, and the other lobe providing a snug fit

about the solid male bead.

1 1 . Belt jointing apparatus according to claim 10 wherein the larger lobe

constitutes an inner lobe, and the snug fitting lobe is an outer lobe, the latter providing a slot with lips for passage of the body of the

strip member.