U.S. patent application number 09/776320 was filed with the patent office on 2001-09-13 for screen and process for manufacturing a screen of this kind.
Invention is credited to Gabl, Helmuth, Pichler, Axel.
Application Number | 20010020600 09/776320 |
Document ID | / |
Family ID | 3653467 |
Filed Date | 2001-09-13 |
United States Patent
Application |
20010020600 |
Kind Code |
A1 |
Gabl, Helmuth ; et
al. |
September 13, 2001 |
Screen and process for manufacturing a screen of this kind
Abstract
A flat or cylindrical screen includes rods and rod-bearing
supporting elements. The rods have protrusions in the side walls
which are received into inversely shaped recesses in a supporting
element. The screen is manufactured by bending the supporting
elements open elastically and inserting the rods, whereupon the
supporting elements spring back, encircle the rods positively and
form a screen mat.
Inventors: |
Gabl, Helmuth; (Graz,
AT) ; Pichler, Axel; (Graz, AT) |
Correspondence
Address: |
Alix, Yale & Ristas, LLP
750 Main Street
Hartford
CT
06103-2721
US
|
Family ID: |
3653467 |
Appl. No.: |
09/776320 |
Filed: |
February 2, 2001 |
Current U.S.
Class: |
210/342 ;
210/323.1; 29/450; 29/896.6 |
Current CPC
Class: |
B07B 1/24 20130101; B01D
33/722 20130101; B01D 29/86 20130101; Y10T 29/4987 20150115; B01D
29/58 20130101; B01D 29/908 20130101; B01D 33/42 20130101; Y10T
29/496 20150115; B01D 29/115 20130101; B01D 33/11 20130101; B01D
29/6476 20130101; B01D 29/902 20130101; B01D 33/466 20130101; B01D
33/68 20130101; B01D 33/727 20130101; B01D 33/073 20130101; B07B
1/20 20130101; D21D 5/16 20130101; B01D 29/118 20130101 |
Class at
Publication: |
210/342 ; 29/450;
29/896.6; 210/323.1 |
International
Class: |
B23P 011/02; B01D
024/00 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 3, 2000 |
AT |
A 165/2000 |
Claims
What is claimed is:
1. A screen comprising a plurality of rods, each of the rods having
side walls, at least one of the side walls defining at least one
protrusion; and at least one rod-bearing supporting element having
at least one recess having a shape which is complementary to the
protrusion of the rod; wherein each protrusion of the rod is
received within a recess of the supporting element.
2. The screen according to claim 1, wherein each protrusion has a
circular or elliptic shape.
3. The screen according to claim 1, wherein each of the rods has an
imbedded end and at least one of the rods has a plurality of
protrusions, the protrusions being positioned at a distance h.sub.1
from the imbedded end of the rod, wherein 0.1 mm<h.sub.1<6
mm.
4. The screen according to claim 1, wherein the supporting element
has at least one side wall and at least one of the rods has three
or more protrusions received within recesses in one side wall of
the supporting element.
5. The screen according to claim 1, wherein each of the rods has
oppositely disposed first and second sidewalls, each having at
least one protrusion, the first sidewall having a different number
of protrusions than the second side wall.
6. The screen according to claim 1, wherein the supporting elements
each have a T-shape.
7. The screen according to claim 1, wherein each of the rods has a
total height H and an imbedded portion protruding into the
supporting element having a height h, where the ratio of h to H is
greater then 0.5.
8. The screen according to claim 1, wherein each of the rods has an
imbedded portion pressed together with the supporting element.
9. Process for manufacture of a screen according to claim 1
comprising the steps of: bending open the supporting elements
elastically; inserting a portion of each rod into one of the open
supporting elements; and allowing the supporting elements to spring
back, wherein the supporting elements encircle the portion of each
rod and form a screen mat.
10. Process according to claim 9, comprising the additional step of
rolling the screen mat to form a cylinder.
11. The screen according to claim 2, wherein the protrusions have a
radius r of 0.1 mm<r<2 mm.
12. The screen according to claim 1, wherein the supporting
elements each have an I-shape.
Description
BACKGROUND OF THE INVENTION
[0001] This invention relates generally to apparatus for cleaning
pulp suspensions. More particularly, the present invention relates
to screens for cleaning pulp suspensions process for manufacturing
screen of this kind Various types of screen are known. For example
WO 98/14658 discloses a screen which comprises a number of rods and
supporting elements, where the supporting elements have slots. In
this case the supporting elements take the shape of a U-shaped
profile, which means that part of these rods must undergo plastic
deformation in order to secure the rods to the supporting elements.
A different kind of screen is known from DE 44 35 538 A1 which
discloses rods secured with positive locking by clamping due to
plastic deformation of the rod-supporting elements. In addition
flat or cylindrical (centripetal or centrifugal) screens are known,
where the rods are attached by welding to the rod-supporting
elements. This form of fastening, however leads to a series of
disadvantages because considerable welding stress is transferred to
the components during welding and this causes distortion of the
entire screen body. Furthermore, the fastening effect is not always
guaranteed because the welds may begin to break up under certain
circumstances and in the course of time due to signs of wear. The
manufacturing process itself is actually very complicated and time
consuming, and it Is very difficult in particular to set the
supporting width precisely between two adjacent screen rods.
SUMMARY OF THE INVENTION
[0002] The aim of the invention is thus to create a screen that
does without plastic deformation of the rods and/or supporting
elements and without welds. In addition, a simple manufacturing
process for this type of screen is to be developed.
[0003] The invention is thus characterized by the rods having
protrusions in the side walls which extend into inversely shaped
recesses in the supporting element. Thus, a fixed connection can be
created with form closure without the need for welding or plastic
deformation.
[0004] An advantageous further development of the invention is
characterized by the protrusions being circular or elliptical and
preferably having a radius r of 0.1 mm<r<2 mm. As a result,
it is possible to mount the rods easily without deformation of the
supporting elements, which also permits manufacture at low cost.
The rods can be inserted easily, whereby the circular or elliptical
formed protrusions lead to a more even area pressure and therefore
to a good fixed connection with the supporting elements.
[0005] An advantageous configuration of the invention is
characterized by the spacing h.sub.1 between the protrusions and
the imbedded end of the rod preferably measuring at least 0.1
mm<h.sub.1<6 mm. This makes the rod more resistant to
vibration.
[0006] A favorable configuration of the invention is characterized
by three or more protrusions with the respective recesses being
provided on one side wall. This means that a secure form closure
can be achieved.
[0007] A favorable further development of the invention is
characterized by a different number of protrusions being provided
on either side of the rods. This guarantees a better fastening
effect en the event of one-sided inflow.
[0008] An advantageous further development of the invention is
characterized by the supporting elements having a T or I shape.
These shapes provide a larger screen area.
[0009] A favorable configuration of the invention is characterized
by the rods, which have a total height H, protruding into the
supporting element to a height h, where the relationship of h to H
is preferably greater than 0.5. This protects the rod more
effectively against flow forces.
[0010] An advantageous configuration of the invention is
characterized by the bottom part of the rod being pressed together
with the supporting element. This provides even better stability at
higher forces.
[0011] The invention also refers to a process for manufacturing a
screen of this kind, characterized by the supporting elements being
bent open elastically and the rods inserted, whereupon the
supporting elements spring back, encircle the rods positively and
form a screen mat. Thus, a screen mat can be formed easily without
welding or pressing, where it is possible to position the rods
exactly and thus, obtain low tolerances.
[0012] An advantageous further development of the invention is
characterized by the screen mat being rolled together to form a
cylinder
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] The present invention may be better understood and its
numerous objects and advantages will become apparent to those
skilled in the art by reference to the accompanying drawings in
which:
[0014] FIG. 1 is a cross section view of a screen in accordance
with the invention; and
[0015] FIG. 2 is a cross section view taken along line II-II of
FIG. 1.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0016] FIG. 1 illustrates an example of three rods 1, mounted in
supporting elements 2. The right-hand rod 1 shows that it has
several protrusions 3 with a radius r on both side walls. The
supporting element contains recesses 4 with exact inverse shaping
and the necessary clearance distances in relation to the screen
basket diameter. The present illustration shows two protrusions and
two recesses on each side, however there can also be three or more
such protrusions and recesses if necessary. The number of
protrusions on either side may also differ. These protrusions with
a circular or elliptical segment shape have a radius r to which 0.1
mm<r<2 mm applies. The rods can be inserted easily, whereby
the circular or elliptical formed protrusions lead to a more even
area pressure and therefore to a good fixed correction with the
supporting elements.
[0017] The middle rod in FIG. 1 shows the length measurements of
the rod, which has an overall height H. The protrusions are spaced
at a distance h.sub.1 to which 0.1 mm<h.sub.1<6 mm applies,
from the imbedded end of the rod. The rod 1 projects into the
supporting element with a height h, where the ration of h to H
should preferably be larger than 0.5. The projecting section of the
rod on the side facing away from the flow can be pressed together
with the surfaces 5 of the supporting element to obtain better
fastening. This applies if the supporting element 2 is made in a T
shape. If an I shape is used, the rod 1 is not pressed together.
The supporting element 2 can also be made in other shapes than a T
or I, e.g. square. rectangular. square with rounded corners,
rectangular with rounded corners, with the rounding on only one or
on several corners. The protrusions provided in the supporting
element 2 to hold the rod 1 can have clearance equivalent to the
angle .alpha. on the side facing away from the flow. With the
cylindrical shape of the screen basket this avoids plastic
deformation in the supporting element 2.
[0018] FIG. 2 shows a section through the line marked II-II in FIG.
1, where the T shape of the supporting element 2 and one rod 1 are
visible. On the surface 5 this rod 1 can be pressed together with
the supporting element 2 if necessary.
[0019] The connection between rods and supporting elements is
essentially positive, i.e. without plastic deformation of the
individual components or additional connecting links, such as weld
seams. A screen of this type can be made, for example, by pressing
the rods together with the supporting elements until they lock into
place. Another form of manufacture is to bend the supporting
elements open elastically so that the recesses 6 for the rods
expand and the individual rods 1 can be inserted. When the
supporting elements have sprung back into place, a level screen mat
is formed by the clamped profile rods. Thanks to the above
mentioned design as snap connection, this process permits the rods
1 to be inserted precisely into the supporting elements 2, thus
lowering the slot width tolerances. If this level screen is then
shaped into a screen basket, the clamping effect is increased
further due to the bending radios when the screen is rolled up.
Pressing the protruding ends of the rods together with the
supporting elements 2 increases the stability of the screen mat
further. The supporting elements 2 can also be shaped as rings with
the protrusions 6 according to the invention worked into these
rings, where the dimensions are somewhat smaller than specified,
i.e. the protrusions 6 are slightly smaller than the rods 1.
Subsequently the rings are nicked at one point and bent open far
enough for the rods to lock into place. When the rings have bent
back into place, they can be welded together to form a basket.
[0020] The invention is not limited to the examples presented. On
the contrary, the protrusions 3 in the rods 1 can be shaped at will
as long as they engage in the inversely identical recesses in the
supporting element. The rods 1 can also take any shape from a
rectangle to a triangle.
[0021] While preferred embodiments have been shown and described,
various modifications and substitutions may be made thereto without
departing from the spirit and scope of the invention. Accordingly,
it is to be understood that the present invention has been
described by way of illustration and not limitation.
* * * * *