Link conveyor especially for paper-making machines

A link conveyor (1, 11), in particular, for paper-making machines, has hinged wires (2, 12) that extend in the lateral direction and link elements (3, 13) that extend in the longitudinal direction and that in each case enclose at least two hinged wires (2, 12), while link elements (3, 13) are shifted over the widths of the link conveyor (1, 11), in the longitudinal direction, by at least one hinged wire (2, 12). According to the invention, the link elements are made as ring elements (3, 13) with one single ring opening (4, 14) that will enclose at least two adjacent hinged wires (2, 12).

This invention relates to a link conveyor, especially for paper-making 
machines, with hinged wires that extend in the lateral direction and with 
link elements that extend in the longitudinal direction and that enclose 
at least two, each, neighboring hinged wires, with the link elements being 
shifted over the width of the link conveyor, in the longitudinal 
direction, by at least one hinged wire. 
Such a link conveyor is disclosed in U.S. Pat. No. 4,469,221. It has a 
plurality of laterally extending hinged wires that have a circular 
cross-section and that are connected via link elements. A plurality of 
differently shaped link elements is shown here and all of them have 
passage openings at their ends to receive two, each, adjoining hinged 
wires. The passage openings are slit so that the passage openings can be 
widened. This makes it possible to allow the link elements to snap 
together with the hinged wires by means of a motion perpendicularly to 
their longitudinal axes. Therefore, one can also exchange individual link 
elements within one and the same complete link conveyor. 
Only limited stability in the direction of traction can be achieved in this 
link conveyor on account of the slit openings. There is a danger that the 
passage openings may be widened and the arches of the link elements that 
limit the passage openings may break. This can spread like a crack so that 
even damage to individual link elements can lead to the complete rupture 
of the link conveyor. It is furthermore disadvantageous that air 
permeability cannot be essentially influenced. But it is precisely air 
permeability that is an essential property in the area in which a link 
conveyor is used for the most part, that is to say, in the dry portion of 
a paper making machine; this is why it must be possible to adjust the air 
permeability to an optimum value. 
Also known are so-called wire link conveyors, such as can be found, for 
example, in U.S. Pat. No. 4,395,308, EP-A-0 050 374, EP-A-0 128 496, 
EP-B-0 292 700, EP-A-0 112 432, EP-A-0 472 072, EP-A-0 171 891, EP-B-0 211 
471, and DE-A-24 19 751. Such wire link conveyors also have a plurality of 
hinged wires extending in the lateral direction, with the hinged wires 
having not only circular, but also flat oval or rectangular or bone-shaped 
cross sections. The hinged wires are connected in the case of wire link 
conveyors by wire spirals that, in each case, grasp two adjoining hinged 
wires and that extend progressively in a spiral fashion in the direction 
of the hinged wires. In the process, they engage particular adjoining wire 
spirals. 
In the case of these wire link conveyors, it is possible to install filler 
elements in the space surrounding the wire spirals, in order thus 
specifically to reduce the air permeability which is generally too great 
(cf., EP-A-0 050 374, EP-B-0 292 700, EP-A-0 128 496, DE-A-24 19 751). A 
disadvantage in the case of wire link conveyors is represented by the fact 
that they are not simple to make. The wire spirals are made by means of 
plastic deformation with exposure to heat so that only thermoplasts can be 
used for this purpose. Besides, left-hand and right-hand spiraling wire 
spirals must be kept ready and must be connected in the proper order so 
that they will engage each other. It is also disadvantageous that the 
damage to one wire spiral can lead to the damage of the entire wire link 
conveyor being torn. 
The object of the invention is so to design a link conveyor of the kind 
mentioned initially that it will be particularly traction-resistant, that 
the air permeability can be adjusted, and that it can be manufactured in a 
simple manner using materials that are not thermoplastic. 
This problem is solved according to the invention in that the link elements 
are made as ring elements with one single ring opening in each case that 
will enclose at least two adjoining hinged wires. 
The basic idea behind the invention is to use ring elements as link 
elements that can be pushed behind each other upon the hinged wires and 
that in each case enclose at least two adjoining hinged wires. Compared to 
the link elements of link conveyors of the kind involved and the wire 
spirals of wire link conveyors, the ring elements according to the 
invention offer a high degree of stability, especially in the direction of 
traction of the link belt. Damage to one of the link elements is not 
critical because the damage cannot be propagated. The ring openings of the 
ring elements furthermore make it possible to receive filler elements in 
order thus to adjust the air permeability of the link conveyor at a 
desired value. In addition, there is the fact that such link conveyors can 
be made in a very simple manner and that one is not confined to particular 
materials for certain parts of the link conveyor. It is therefore also 
possible to use duromers, where the ring elements can be made by punching 
up of a tape or by cutting correspondingly shaped pipes off. In this way, 
one can provide highly-resistant link conveyors at relatively low cost. 
By way of a further development of the invention, it is provided that the 
height of the ring openings is constant over their extent in the 
longitudinal direction, so that the height of the ring openings should 
correspond to the height of the hinged wires. But other to designs of ring 
openings are also conceivable. 
It is furthermore proposed that the ring elements have a straight, 
preferably flat surface on top and/or underneath. Deviating from that, it 
is possible to make the surface also convex or concave in order to achieve 
better adaptation to the particular conditions. 
Basically, all possible cross-sections can be considered for the ring 
elements, for example, round or oval cross-sections. But it may also be 
practical to give the ring elements a square or rectangular cross-section, 
in particular, if one wants a flat surface. 
The hinged wires can have a circular cross-section in the known manner. In 
this cross-section shape, the hinging capacity, and thus the divertability 
of the link conveyor, is particularly pronounced. But it is also possible 
to make the hinged wires oval or as flat wires (see all U.S. Pat. No. 
4,395,308), so that their flat sides will extend parallel to the plane of 
the conveyor belt. Such hinged wires improve the traction-strength of the 
link conveyor or, in case of identical, constant traction resistance, it 
is possible to make particularly flat link conveyors. The air permeability 
can also be influenced in the desired manner by setting the height-width 
ratio. It is recommended that the hinged wires be rounded on the front 
regardless of their cross-section to support the hinging function. 
In this particular link conveyor, one can also make provision to the effect 
that the support of the ring elements on the hinge wires is so made that 
the ring elements will be swung around the hinge axes that are shifted 
with respect to the mid-plane of the link conveyor. This design, known in 
the case of wire link conveyors (EP-B-0 472 072, which will be made 
reference to as to its full content) offers the advantage that the actual 
hinge axis, in the direction of the contact surface, is shifted between 
the track to be transported and the link conveyor and that the relative 
motion between the link conveyor and the track is reduced as the ring 
elements are swung. 
According to the invention, it is also provided that the particular 
adjoining ring elements are shifted with respect to each other by one 
hinged wire. In this way, one gets a particularly uniform structure of the 
link conveyor. 
By way of a further development of the invention, it is proposed that the 
ring elements have broadened segments on one or both flat sides of the 
link conveyor, where the segments preferably extend in the longitudinal 
direction up to a point close to the hinged wire that is enclosed by the 
particular pertinent ring element. Such widened segments are known in 
connection with wire link conveyors from EP-A-0 112 432, EP-A-0 171 891 
and EP-B 0 211 471. With the help of these widened segments, one can 
adjust the air permeability of the link conveyor to a desired degree, 
something that is useful particularly for use from the dry portion of a 
paper making machine sic!. Besides, this way one can enlarge the 
supporting surface for the paper track, specifically, in particular, if 
the segments of laterally adjacent ring elements are so wide that they 
form an essentially compact surface in the area of the segments. 
The link conveyor according to the invention can also have a layer on at 
least one of the flat sides, for example, a fiber layer, a fabric, a 
knitted material, a folded material and/or a foil, as is known in 
connection with wire link conveyors particularly in combination with the 
above-described widened segments (cf, EP-A-0 171 891, EP-B-0 211 471). In 
this way, one can adapt the surface conformation of the link conveyor in 
accordance with particular requirements. In the process, one can also 
consider a combination of such layers, for example, a fabric or a knitted 
material with a fiber layer pinned on. 
According to the invention, it is further provided that the hinged wires 
are made up of one or several monofilaments, multifilaments, and/or yarns 
embedded in a casing, such as this, has already been proposed in 
connection with wire link conveyors (cf, EP-B-0 292 700, to which 
reference will be made in full). 
The ring elements can be made of whole plastics, so that the plastic 
material used can be adapted to the particular requirements corresponding 
to its properties. In case of higher requirements, particularly as regards 
mechanical strength, one can also consider ring elements that are made of 
a plastic provided with a reinforcement. The reinforcement can consist of 
fibers, threads, knitted material, fabrics, and/or folded threads. 
In the simplest embodiment, the ring elements enclose two, each, adjoining 
hinged wires. But it is also possible to have the ring elements enclose 
three or more successive hinged wires so that, by correspondingly 
staggering the ring elements, one can keep the interval of the hinge bars 
constant also in this particular design.

In the link conveyor shown in FIG. 1, the longitudinal extent and thus also 
the provided running direction of the link conveyor 1 is symbolized by the 
double arrow A. In this direction, link conveyor 1 forms a compact endless 
belt. 
Link conveyor 1 has a plurality of hinged wires that extend in the lateral 
direction and that are labeled, by way of example, with the number 2. The 
hinged wires have a flattened cross section that is very wide and, in 
contrast to that, they have a low height, with a width-height ratio of 
about 5:1. Hinged wires 2 are level on top and underneath and are rounded 
in a semicircular fashion along the front and rear sides looking in the 
direction of movement. They are in each case at equal intervals from each 
other. 
Two adjoining hinged wires 2, each time, are enclosed by a ring element, 
labeled 3, by way of example, together in a single opening, labeled 4. 
Ring elements 3 are adapted to the shape of hinged wires 2 in such a way 
that ring openings 4 will be oval and will throughout have a height that 
corresponds to the height of the hinged wires 2. On the front and rear 
edges, looking in the direction of motion, the ring elements are bent in a 
semicircular fashion so as to adapt to the rounded portions of hinged 
wires 2. 
Ring elements 3 in this embodiment have a square cross section and extend 
straight, both on top and underneath. In this way, one can form planer 
surfaces, labeled 5, by way of example. 
Two adjoining ring elements 3, in each case, are arranged around a hinged 
wire 2, in a manner shifted longitudinally with respect to each other. 
This means that a first ring element 3 will enclose two specific hinged 
wires 2, while the two adjoining ring elements 3 are so staggered that the 
first ring element of the two above-mentioned hinged wires 2 will enclose 
only one and, additionally, the hinged wire 2 that follows next in the 
longitudinal direction of the other ring element 3 that lies behind it in 
the longitudinal direction of the two above-mentioned hinged wires 2, will 
enclose only the other and, additionally, the hinged wire 2 that adjoins 
on the other side. This pattern is continued in a steady sequence so that 
two adjoining hinged wires 2, looking in the lateral direction of link 
conveyor 1, will be enclosed, together, only by every other ring element 
3. 
In the above-described pattern, ring elements 3 can be pushed upon hinged 
wires 2 in a simple manner. This process can also be mechanized so that 
one can make big link conveyors 1 in a simple and fast fashion, such as 
these link conveyors are needed, for example, in the dry portion of paper 
making machines. In the process, ring elements 3, between hinged wires 2, 
enclose ducts 6 that extend in the lateral direction over the entire width 
of link conveyor 1 into which one can insert filler elements such as can 
be found, for example, in EP-A-0 050 374 or EP-A-0 128 496. In this way, 
one can reduce the air permeability of the link conveyor to a desired 
value. 
Link conveyor 11, shown in FIG. 2, whose direction of movement is 
symbolized by double arrow B, also has a plurality of hinged wires that 
extend in the lateral direction and that are labeled 12, by way of 
example, and that, in this particular case, have a circular cross section. 
Two adjoining hinged wires 12, each, are enclosed by one ring element, 
labeled 13, by way of example. Ring elements 13 are so fashioned that an 
oval ring opening 14 is formed and it has the same height throughout, so 
that the height will correspond to the diameter of the hinged wires 12. On 
the front and rear ends, looking in the direction of movement, ring 
elements 13 are bent in a semicircular fashion so as to adapt to the 
hinged wires 12. 
Ring elements 13 have a rectangular cross section and extend straight, both 
on top and underneath. In this straight sectors, ring elements 13 have 
widened segments--labeled 15 and 16, by way of example--that protrude 
toward both lateral sides on top and underneath; segments 15, 16, of 
laterally adjoining ring elements 13, are practically placed against each 
other so that, in the sector of these segments 15, 16, one gets an almost 
compact surface. 
As for the rest, the arrangement of ring elements 13 with respect to each 
other corresponds to the embodiment shown in FIG. 1, that is to say, in 
the area of hinged wires 13, a first ring element 13 that encloses two 
specific hinged wires 12, will, in each case, alternate with an adjacent 
ring element 13 which is shifted by one hinged wire 13 in the longitudinal 
direction (arrow B). In this way, two adjacent hinged wires 12--looking in 
the lateral direction of link conveyor 11--will be enclosed together only 
by every other ring element 13. 
In this link conveyor 11, likewise, ducts 17 are formed and extend 
laterally over the entire width. Naturally, one can also insert into these 
ducts 17 filler elements such as they are known, from EP-A-0 050 374, 
EP-A-0 128 496, DE-A-24 19 751, and EP-B-0 292 700. As a rule, however, 
because of the presence of segments 15, 16, one can get along without such 
filler elements in this particular embodiment.