Note: Descriptions are shown in the official language in which they were submitted.
TREATMENT FITTING FITTING FOR THE TREATMENT OF AQUEOUSLY
SUSPENDED FIBROUS MATERIAL
The invention comprises a fitting for the treatment of
aqueously suspended fibrous material in a treatment gap
bounded by two treatment surfaces rotating relative to
each other about an axis of rotation and formed by
fittings, comprising a base body with elongated treatment
elements facing the gap and at least one directional
component extending radially, produced by the method
according to the invention.
Fittings of said type are intended to be suitable for the
mechanical treatment of suspended fibrous material. This
primarily means the refining of paper fibers, dispersion
of contaminants and fibers and deflaking, that is to say
the disintegration of fiber agglomerates.
Fittings are installed, for example, in refining machines
- so-called refiners. The suspension in refiners has a
solids content of about 2-8%.
Similar consistencies are also run in deflakers.
In machines for higher consistencies, reference is made,
for example, to high consistency refiners, dispergers or
kneaders.
The mechanical treatment taking place therein can cover
the whole of the fibrous material, therefore also the
dispersion of contraries contained therein.
Such machines have at least one rotor and at least one
stator with either disk-like or wedge-like surfaces, to
which the fittings are attached, so that gaps can be
formed between them. Many fittings have webs and grooves
on the working surfaces, for which reason mention is also
made of "blade fittings". Other fittings have the shape
of toothed rings.
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It is known that, in addition to the shape of such webs,
grooves and teeth, the material of which they are
composed also has effects on the processing of the
fibrous material.
The fittings are subjected to wear and must therefore be
replaced at specific intervals. In addition, the wear can
lead to the processing action changing during the service
life.
A considerable part of the operating costs which arise
during the mechanical treatment of fibrous materials in
the pulp and paper industry originates from the energy
costs. Therefore, there have always been attempts to
construct and operate fittings and the machines used in
such a way that - measured by the desired success - an
excessively high input of energy is not required.
It is therefore understandable that, for the development
of fittings, a considerable amount of effort is expended,
which is reflected in the configuration of the shape and
in the selection of the material.
In order to reduce the expenditure on manufacture of the
fittings, it is proposed, for example in DE 10 2004 016
661 Al, to assemble the fittings from a plurality of
elements and then to weld or to braze these to one
another.
It is known from FR 2 707 677 Al that the knife surface
of the set is to be covered with an abrasive material by
means of a laser.
The object of the invention is to widen the freedom of
configuration in such fittings with economically
tolerable outlay.
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Ac co r di ng to the invention, the object has been
achieved in that the treatment elements are applied at
least partly as layers of a liquid or solid material
and are subjected to a physical or chemical curing or
fusing process.
As a result of the application as layers, material and
shape of the treatment elements can be adapted more
simply and more comprehensively to the specific
requirements.
It is advantageous if in each case a core of the
treatment elements is connected in one piece to the
base body, and at least one outer region, preferably
the outer part of the treatment elements facing the
treatment gap, is applied as layers of a liquid or
solid material and is subjected to a physical or
chemical curing or fusing process.
In this way, the treatment elements can be provided
with a wear layer. If, here, the
color of the core
should differ from that of the outer part of the
treatment elements, then conclusions can be drawn about
reaching the wear limit via the color change.
In addition, the reconditioning of worn fittings is
possible by the application of the wear layer.
The core of the treatment elements not only functions
as a connecting element to the base body but also
reduces the quantity of required and normally
expensive, wear-resistant material.
However, should the arrangement and configuration of
the treatment elements be given more freedom, it is
advantageous if the treatment elements as a whole are
applied as layers of a liquid or solid material and are
subjected to a physical or chemical curing or fusing
process.
This also permits the use of universally usable base
bodies.
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Since the material applied as layers is normally
expensive, in this way a cheaper, different material
can be used in the base body.
Because of the high loading in such machines for
refining, dispersing or deflaking fibrous materials,
the material applied as layers should be powdery and/or
comprise one or more metals or metal compounds.
Here, it is advantageous if the material applied as
layers is sintered or fused by means of lasers.
Ceramic layers can also be produced in this way.
Furthermore, the surface roughness of the treatment
element can be influenced by the grain size of the
powder.
The production method according to the invention makes
it possible to select materials in accordance with the
specific requirements, for which reason at least part,
preferably the whole, of the surface of the treatment
elements respectively formed by two side surfaces and
the upper side located in between and directed towards
the gap should consist of a material which differs from
the material of the base body. Thus, the treatment
elements can be configured to be very wear-resistant
with the minimal use of expensive materials such as
tungsten carbide.
Because of the generally higher loading of the
treatment elements with regard to the base body, at
least the plurality, preferably all, of the treatment
elements should in particular consist entirely of a
material which differs from the material of the base
body.
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B y means of material selection, but in particular by
means of the application as layers, it is possible to
form at least the surface of the treatment elements
that faces the gap in a profiled manner, which improves
the fibrillation of the fibers.
It is advantageous if this profile of the upper side of
the treatment elements is formed by recesses, which are
bounded by webs extending between them and, at the edge
of the upper side, also by webs forming part of the
side surface of the treatment elements.
Because of the high stress on this profile during the
rotation of the treatment surfaces and during the
treatment of the fibrous material suspension, at least
along a side surface of the treatment elements which
preferably points in the direction of rotation in the
case of a rotating treatment surface and points counter
to the direction of rotation in the case of a
stationary treatment surface (the other, rotating
treatment surface), the webs should have a greater
width than the webs extending between the recesses.
Comprehensive protection of the profile independently
of the direction of notation can be ensured in that,
along both side surfaces of the treatment elements, the
webs which form a part of the side surfaces have a
greater width than the webs extending between the
recesses.
With regard to the production method preferred here, in
the interests of simplification of the same, it has
proven to be advantageous for at least the outer region
of the treatment elements, lying below the profile, to
be filled completely with the appropriate material over
a thickness of at least 2 mm, preferably at least 4 mm,
the density of this material in the sections with the
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webs located above being higher than in sections with
recesses located above.
This thus permits a flat application of the in
particular powdery material as layers over the entire
cross section of the treatment element, the applied
material then being subjected to a fusing process,
preferably by means of lasers, only or particularly
intensively in the region of the webs.
Because of the small dimensions of the recesses and
webs, in the region of normally substantially less than
1 mm, this is extremely simplifying for the production.
If the profile of the treatment elements is abraded as
a result of wear, then material is also increasingly
detached or washed out of the recesses, so that a
specific profile depth remains ensured over a long
operating period. The detached material is not critical
to the fibrous material treatment process, because of
the small quantity of material in relation to the
quantity of fiber treated.
Alternatively or additionally, it can likewise be
advantageous if the profile of the webs changes at
least partly at right angles toward the upper side of
the treatment elements. In this way, it is possible to
implement recesses under the upper side of the
treatment elements which are opened towards the upper
side only with increasing wear. Therefore, permanent
closure of the recesses via fibrous materials or fines
can be countered effectively and the stability of the
treatment elements can be increased.
In general, treatment machines for fibrous material
preparation have circular or annular treatment surfaces
which are assembled from a plurality of fittings. Here,
the advantages of the production method according to
the invention with regard to production feasibility and
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ec onomy manifest themselves, in particular when the
base body has the shape of a circular segment or an
annular segment and the product of segment angle (in )
and the circular diameter (in cm) is greater than 6000,
preferably greater than 6500. The production process
according to the invention permits larger fittings and
thus reduces their number per treatment area, which
improves the homogeneity of the treatment.
The circular diameter of the base body should lie
between 35 and 150 cm.
As distinct from the previously usual casting of the
fittings, the method according to the invention makes
it possible to reduce the thickness of the base body
and therefore also its material requirement and weight.
It has proven to be particularly advantageous that the
thickness of the base body is lower than the height of
the treatment elements and in particular makes up less
than 85%, preferably less than 75%, of the height of
the treatment elements.
When considering the thickness of the base body,
locally limited thickenings, for example for fixing in
the housing or the like, remain disregarded.
As a result of the deliberate use of very wear-
resistant materials, the height of the treatment
elements, starting from the base body, can be reduced
with the same operating time, which in turn simplifies
its application as layers. Added to this is a reduced
idling power of the machine, a low height of the
treatment elements being advantageous.
Therefore, the height of the treatment elements should
at least partly, preferably wholly, lie below 5 mm,
preferably below 4 mm.
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In order to intensify the treatment, the production
method according to the invention, as distinct from the
previously usual casting, permits very narrow treatment
elements and likewise short distances between adjacent
treatment elements. For this reason, the treatment
elements should have an elongated cross-sectional shape
parallel to the base surface and, at least partly,
preferably wholly, have a width between 0.1 and 5 mm,
in particular between 0.1 and 1 mm, and/or the distance
between adjacent treatment elements should at least
partly, preferably wholly, lie between 0.1 and 5 mm, in
particular between 0.1 and 2 mm.
Furthermore, it is advantageous if the radius at the
transition between base body and treatment element is
less than 1 mm, preferably less than 0.3 mm, and the
treatment elements can be implemented without any
molding draft. This leads to a larger open useful
surface, an improved conveying action of the fittings
and to optimal utilization of the treatment area.
The method according to the invention now also permits
undercuts in the treatment elements. Thus, for example,
it may be advantageous for at least one side surface of
the treatment elements to be inclined in relation to a
normal to the direction of rotation of the treatment
surface.
In order to produce a conveying action with regard to
the fibrous material to be treated, in the case of a
rotating treatment surface, the side surface of the
treatment elements pointing in the direction of
rotation should be inclined counter to the direction of
rotation in relation to a normal to the direction of
rotation.
In the interests of an optimal arrangement of the
treatment elements, it is often advantageous if, at
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least in some sections, the elongated treatment
elements extend non-rectilinearly, i.e. are curved or
have a bend.
By means of the preferred production method, this is
now also possible in conjunction with inclined side
surfaces.
The invention is to be explained in more detail below
by using a number of exemplary embodiments.
In the appended drawing:
Figure 1 shows a schematic cross section through a
refining arrangement;
figure 2 shows a plan view of a fitting 2, 3 of the
refining arrangement;
figures 3-6 show cross sections through different
fittings 2, 3 and
figures 7-9 show plan views of two different treatment
elements 6.
In the housing of the refining arrangement, according
to figure 1, a refining gap 4 is formed by a stationary
refining surface coupled to the housing and a refining
surface rotating about an axis of rotation 15.
The two annular refining surfaces (treatment surfaces)
extend parallel to each other, the distance between
these normally being adjustable.
The rotating refining surface here is moved in the
direction of rotation by a shaft 16 rotatably mounted
in the housing. This shaft 16 is
driven by a drive,
likewise present in the housing.
The fibrous suspension 1 to be refined in the example
shown here reaches the refining gap 4 between the two
refining surfaces via a feed through the center.
However, a feed via openings in the fitting is also
possible.
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The fibrous suspension 1 passes the interacting
refining surfaces radially toward the outside and
leaves the adjacent annular chamber through a
discharge.
Not illustrated are the means, known per se, with which
a force is produced in order to press the two refining
surfaces toward each other.
The two refining surfaces are each formed by a
plurality of refining fittings 2, 3 in the form of
circular segments or annular segments according to
figure 2, which each extend over a circumferential
segment of the corresponding refining surface.
In the circumferential direction beside one another in
a row, the fittings 2 result in the stationary refining
surface, and the other fittings 3 result in the
rotating refining surface.
As shown in figure 2, the fittings 2, 3 are each formed
by a base plate 5 having a multiplicity of bar-like
treatment elements 6 extending substantially radially
and grooves 9 located in between.
The cross section of the treatment elements 6, also
called knives, is generally rectangular, as illustrated
in figures 3, 4 and 6, but there are also other shapes.
Thus, according to figure 5a-c, one or both of the side
surfaces 18 of the treatment elements 6, usually
extending approximately at right angles to the
direction of rotation 17 of the refining surface, can
also be inclined in or counter to the direction of
rotation 17. A delivery action in the refining gap 4
and therefore also an intensification of the fiber
treatment is achieved if, as shown in figure 5a-c, in
the case of a rotating refining surface the side
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surface 18 of the treatment elements 6 that points in
the direction of rotation 17, is inclined counter to
the direction of rotation 17 in relation to a normal to
the direction of rotation 17.
According to figure 5c, both sides of the treatment
elements 6 are inclined in the same direction.
In order in particular to reinforce the upper region of
the treatment elements 6 because of its high wear,
according to figure 5a the side surface 18 that points
counter to the direction of rotation 17 can be inclined
counter to the direction of rotation 17 or, as in
figure 5b, extend at right angles to the direction of
rotation 17. However, the variation in the inclinations
of the side surfaces 18 is not restricted thereto but
can also be carried out depending on the intended
action, for example even in the case of stationary
refining surfaces.
Parallel to the base surface 5, the treatment elements
6 have an elongated cross-sectional shape, the upper
side 19 of the treatment elements 6, facing the
treatment gap 4, generally extending parallel to the
outer surface of the base body 5.
For the purpose of optimizing the arrangement and its
action, the treatment elements 6 frequently run non-
rectilinearly, at least over a radial section, i.e. in
a curve, in a wavy form or, as can be seen in figure 2,
in a bent form.
This is now possible in conjunction with the following
production method, even in the case of inclined side
surfaces 18.
In order to reduce production costs of the fittings 2,
3, only the treatment elements 6 of the fittings are at
least partly applied as layers of a liquid or solid
material and thereby subjected to a physical or
chemical curing or fusing process.
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Th i s means that the materials can be selected in
accordance with the specific stresses and requirements.
Thus, in particular, the base body 5 can be cast from
an inexpensive metal and have the same shape for
differently configured fittings 2, 3. Even re-use of
the base body 5 is possible.
Since the base body 5 is not subjected to any increased
wear during operation, there are no specific
requirements on its wear resistance either.
By contrast, the treatment elements 6 are subjected to
increased wear, for which reason at least part of the
surface of the treatment elements 6 respectively formed
by two side surfaces 18 and the upper side 19 formed in
between and directed toward the gap 4 consists of a
wear-resistant material which differs from the material
of the base body 5.
Because of the extremely high stress in machines for
the treatment of fibrous material 1, the application as
layers of powdery material, which comprises ceramic or
one or more metals or metal compounds, is particularly
suitable. This material applied as layers can then be
sintered or fused by means of lasers after each layer.
In figure 3 and 5, the arrangement of the treatment
elements 6 on the base body 5 can be chosen as
required.
This is made possible by the fact that all the
treatment elements 6 consist wholly of a material which
differs from the material of the base body 5.
Therefore, the treatment elements 6 as a whole can be
applied as layers of a liquid or solid material and be
subjected to a physical or chemical curing or fusing
process.
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Differing from this, the treatment elements 6 in figure
4 and 6 each have a core 7 connected in one piece to
the base body 5. Therefore, although the arrangement of
the treatment elements 6 is predefined, on the other
hand very strong fixing to the base body 5 is also
ensured by the cores 7.
Accordingly, also only an outer region of the treatment
elements 6 is applied as layers of a liquid or solid
material and subjected to a physical or chemical curing
or fusing process.
Whereas in figure 4 the complete surface of the
treatment elements 6 is produced as layers, in figure 6
this is carried out only on the upper side 19 facing
the treatment gap 4.
In this case, for example, tungsten carbide is suitable
as an outer wear layer for the layered structure, a
thickness of this wear layer of 1 mm normally being
adequate.
Since the material applied as layers often differs in
terms of color from the material of the base body 5,
complete abrasion of the material applied as layers on
the upper side 19 of the treatment elements 6 that
points toward the gap 4 can easily be detected.
This primarily applies to the treatment elements 6 with
core 7, which are particularly well suited to
reconditioning of worn treatment elements 6.
In order to improve the fibrillation of the fibres, at
least the upper side 19 of the treatment elements 6
that points toward the gap 4 can be configured so as to
be profiled. This profile substantially comprises
recesses 20 on the upper side 19, which are delimited
via webs 21 extending between the recesses 20 and, at
the edge of the upper side 19, also by webs 22 forming
part of the side surface 18 of the treatment elements
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6. In figure 7 and 9, the recesses 20 are formed by
slots open toward the gap 4 and, in figure 8, by open
honeycombs.
Since the profile is subjected to high stress, in
figure 8 the webs 22 along a side surface 18 of the
treatment elements 6 have a greater width than the
other webs 21, in particular those extending between
the recesses 20.
The reinforced webs 21 are located on the side pointing
in the direction of rotation 17 in the case of a
rotating refining surface and, in the case of a
stationary refining surface, on the side pointing
counter to the direction of rotation 17 (the opposite,
rotating refining surface).
Differing from this, in figure 7 the webs 22 along both
side surfaces 18 of the treatment elements 6 have a
greater width than the webs 21 extending between the
recesses 20.
It is also important here that the outer region of the
treatment elements 6, located under the profile, is
filled completely with the appropriate material over a
thickness of at least 4 mm, the density of this
material in the sections with webs 21, 22 located above
being higher than in sections with recesses 20 located
above.
Whereas this density difference in figure 3b extends by
way of example over a substantial part of the treatment
element 6, in figure 6a it is to be found as far as the
core 7.
This simplifies the production, since the powdery
material for the treatment element 6 no longer has to
be applied exactly only for the webs 21, 22 but can
also come to lie in the region of the recess 20 located
above in the direction of the gap 4.
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Howe ve r , the sintering of this material following the
application of each layer is then carried out to the
greatest extent only in the region of the webs 21, 22
located above in the direction of the gap. While the
part of the material that is fused on is relatively
hard and wear-resistant, the part of the material not
treated or treated only slightly by the laser is
porous. With increasing wear of the profile, this
porous material is washed out, which leads to a
deepening of the original recess 20. As a result, the
fitting 2, 3 remains usable for substantially longer.
Figure 9 shows an embodiment in which the profile of
the webs 21, 22 changes at right angles toward the
upper side 19 of the treatment elements 6. With
increasing abrasion of the profile as a result of wear,
new recesses 20 are opened. In practical terms, the
treatment elements 6 here consist of a plurality of
layers arranged one above another toward the refining
gap 4, the webs 21 of one layer extending substantially
over the slot-like recesses 20 of the layer located
underneath.
In this way, the action of the profile can be
maintained over a long operating time.
Since the whole fitting 2, 3 is no longer cast, the
thickness 11 of the base body 5 can be lower than the
height 10 of the treatment elements 6, which has a
positive effect on the weight and the ability to handle
the fitting 2, 3. This in turn likewise permits the
segment angle 8 of the fitting 2, 3 to be chosen to be
greater than usual, so that the product of segment
angle 8 (in ) and the circular diameter (in cm) is
greater than 6000, preferably greater than 6500. Here,
the circular diameter of the base body 5 lies between
35 and 150 cm.
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Fo r example, the height 10 of the treatment elements 6
is less than 5 mm here, the width 12 of the treatment
elements 6 is between 0.1 and 1 mm, and the distance 13
between adjacent treatment elements 6 is between 0.1
and 2 mm.
The new production method additionally permits smaller
radii 14 of less than 0.3 mm at the transition between
base body 5 and treatment element 6, which is positive
for the conveying action.
