Note: Descriptions are shown in the official language in which they were submitted.
CA 02509069 2005-06-07
VIBRATING PLATE
The invention relates to a vibrating plate according to the preamble of the
claim 1
with a baseplate that can be set in vibration by a driver device.
Usually such a baseplate comprises a bottom plate, the bottom side of which is
flat and
has vibrating effect on the material to be compressed. Due to the high dynamic
load,
most of the baseplates are produced from massive thick steel plates, which are
stabilized further through welded supports.
A soil compaction plate is known from DE 4307993 C2, in which the baseplate is
constructed as a ribbed hollow plastic part, which is filled with sand or
water before
application. This plastic baseplate, which is loaded with ballast, are alleged
to have only
low noise development during the soil compaction and more convenient to
fabricate. In
particular, the ribs extend from a cover plate above up to the bottom plate
and are built
in particular as an open-cell web structure. The web structure serves thereby
the
purpose of increasing the mechanical strength of the plastic component, and
the open-
celled form enables the filling and distribution of water or sand to ballast
the baseplate.
Such familiar vibration plates are used successfully in many areas of soil
compaction applications. However, it was found that during the compaction of
uniform
and close-stepped sand, the use of the conventional plates leads, among other
things, to
grain refinement due to breaking up of the grains and abrasions.
Disadvantageous
thereby is that the grain refinement due to the mechanical action, changes the
soil
mechanical properties of the mixture, for example, the permeability,
sensitivity to frost,
compaction properties, during its emplacement.
CA 02509069 2005-06-07
18-02-05 2 EP0314012
[0004] Problematic is also the quietness of the run of the known vibration
plates. Thus, it
can happen that with increasing compaction of the soil, the traditional
vibration plates
execute irregular vibrations and rocking motions.
[0005] The underlying task posed by the invention is therefore to devise a
vibrating plate
with a baseplate that can be set in vibration by a driver device, such that
during its
application no more heavy grain refinement takes place and the quietness of
the run is
improved at the same time.
[0006] This task is solved with a vibrating plate according to claim 1 and a
baseplate
according to claim 22. Further advantageous embodiments are described in the
dependent claims.
[0007] The vibrating plate according to the invention has a baseplate that can
be set in
vibration by a driver device, and as supporting components it has at least a
bottom plate,
an upper plate and a cell structure that reinforces the baseplate, arranged
between the
bottom and the upper plate, whereby the supporting components form a baseplate
with a
rigidity, for which the lowest eigenfrequency of the baseplate is at least 2
to 5 fold,
preferably 3 to 4 fold, the frequency of its oscillations.
[0008] Therefore, with this new vibration plate, the supporting components are
now
connected with each other in such a fashion that they form a body with very
specific
oscillation properties. The characteristics of a vibrating plate during a run
always
improve significantly if the supporting components reinforce at least the
bottom plate in
such a fashion that the lowest eigenfrequency of the baseplate lies in the
aforementioned range of frequencies of its oscillations during the soil
compaction. As a
rule, high stiffness together with low weight generates high eigenfrequencies,
whereby
the lowest eigenfrequency of the bandwidth of the eigenfrequencies of the
baseplate
should have a certain minimum value. Such a baseplate swings harmonically over
a
longer period with the increasing compaction of the soil before developing
irregular and
undesired wobbly and tilting motion.
[0009] For that, in contrast to DE '993, the baseplate must be very light,
particularly
during the compaction. To that end, the known supporting components used in
aircraft
construction for reinforcement in the known manner are used for lightweight
construction. Thus, a particularly stiff and yet light baseplate is
constructed, which has
eigenfrequency values according to the invention.
[0010] In particular, a cell structure is used, so as to enable use of bottom
plates or
upper plates that are considerably thinner than the ones used hitherto.
According to the
invention, this construction allows use of 4 to 8 mm thick steel sheet metal
plates, which
enable considerable weight reduction compared to the known vibration plates
made from
steel.
CA 02509069 2005-06-07
WO 2004/053232 3 PCT/EP2003/014012
[0011 ] The vibration plates according to the invention have therefore
significantly less
swinging mass. This has the advantage that the amplitude necessary for
ensuring
adequate compaction with less centrifugal force can be generated. Therefore,
less
flyweights can be used, which, on their part, can be driven with less power.
Thus the
undesired grain refinement is reduced and, at the same time, the driver device
can be
operated more economically.
[0012] Moreover, it is just this significant reduction in the weight, which
enables use of
vibration plates for compaction of a heap of debris of a general sort. A heap
of debris in
the present context means a loose storageable aggregate, built from more or
less
unequally large and loosely lined up single grains with large porous cavities
in between.
Through compaction, these loose storageable aggregate can be transformed into
a
dense, storageable aggregate with pore-filling gradations, with fewer
cavities. Thereby
the grains can be, for example, sand or gravel grains, as well as also snow
and ice
crystals. Thus the vibrating plate according to the invention can also be used
in the
maintenance and preparation of the ski runways, ski circuits or ski-jump
landing runs, for
achieving longer service lives, without the risk of its submerge into the
snow. This area
of application has not been explored in the conventional vibration plates due
to the
massive or ballast-loaded embodiments of the bottom plates and the heavy
weights
resulting from that.
[0013] The excitation of the vibrations of the bottom plate takes place
thereby with the
help of a driver device. It can, for example, be a circular drive or an
aligning vibrator
mounted on the baseplate. Thinkable in this connection is the excitation by
means of a
single driver or several hydraulically or mechanically synchronized drivers.
Alternatively,
continuous waves with one or more driver weights can also be used as circular
drive or
as an aligning vibrator. Also, eccentrically supported waves can also be used
here.
[0014] In a further preferred embodiment, the supporting components are welded
on
each other to form a self-supporting body. By welding the bottom plate with
the cell
structure on the upper plate, an extraordinarily sturdy body with further
improved
vibration properties is obtained, which can be handled easily during the
production itself.
[0015] This light design also enables a significantly broader embodiment of
the plates in
the direction orthogonal to the direction of work. Thus, baseplates from thin,
high-
strength steel, with widths of about 2.25 m and contact surface of about
10,000 cm2, can
be built, which lead to vibration plates with less than 400 kg weight. The
corresponding
surface pressure of such a vibrating plate amounts then only just 0.4 N/cm2
instead of
the usual 5 N/cm2. As a rule it is advantageous, if the surface pressure of
the vibrating
plate due to its own weight lies between 0.1 N/cm2 and 3 N/cm2.
CA 02509069 2005-06-07
WO 2004/053232 4 PCT/EP2003/014012
Own weight of the vibrating plate means here the total weight of the ready-to-
use
vibration plate. To that counts, among other things, the weight of the
baseplate, the
weight of the driver device including the weight of possibly present drives
and / or
suspension devices of the vibration plate. Thereby, the surface pressure due
to own
weight is the force of weight resulting from its own weight, which the
vibrating plate
exerts on the plane surface of the soil contacted by it.
[0016] According to the invention, the oscillation of the baseplate is
adjustable by
selection of a frequency between 30 Hz and 60 Hz. Thus, from the frequency of
30 Hz,
higher frequency values can be set in continuous or graduated steps or in a
fixed single
step. This frequency adjustment is necessary particularly in the compaction of
heaps of
debris, whereby the sand is compacted at about 60 Hz.
[0017] In an another embodiment, the oscillation of the baseplate can
selectively be set
with an amplitude of greater than 0.1 mm and less than 10 mm, preferably 5 mm.
The
setting of the amplitude of 0.1 mm to higher amplitude values can take place
in
continuous, graduated steps or in a fixed single step.
[0018] Another enhancement is a reinforced baseplate, such that it comprises,
as
another supporting component, at least one longitudinal girder welded with the
cell
structure. This component extends parallel and over a significant part of a
longitudinal
side of the baseplate. Here, the longitudinal side of the baseplate means the
longest
side of the baseplate. Significant in this embodiment is that the longitudinal
girder
considerably reinforces the flexural and torsional strength of the baseplate.
Further, due
to the welding of the support on the cell structure, it holds better, which on
its part
increases the overall sturdiness of the baseplate further. Especially suitable
supports are
those fabricated with a closed ring-shaped or box-shaped hollow profile.
[0019] It is more effective if the longitudinal girder is arranged below the
driver device.
Thus the baseplate is strengthened additionally especially in the high-load
region below
the driver device and, furthermore, an alternative for fastening the driver
device to the
baseplate, for example through screws, welding or rivets, is provided.
[0020] In order to further increase the overall rigidity of the vibration
plate, and in
particular of the baseplate, the longitudinal girder is built as a frame
fitted on the bottom
plate. Through that, a significantly greater spatial reinforcement of the
longitudinal girder
itself is achieved, which can be increased still further by welding the cell
structure to be
reinforced in the intermediate space enclosed by the frame. Further, as
already
described above, the cell structure is welded around the frame. This design of
the
support enables fastening of relatively broader driver devices on the
vibration plate.
CA 02509069 2005-06-07
WO 2004/053232 5 PCT/EP2003/014012
[0021] In an especially preferred enhancement of the embodiment, each of the
individual
cells of the cell structure have a base area, whose maximum lateral extension
lies
between 20 mm to 200 mm, preferably between 56 mm and 162 mm. These very fine-
celled cell structure enables, due to the narrow supporting distances of the
cell walls, to
design very thin bottom plates, without the risk of a severe dent in the only
4 to 8 mm
thin bottom plates.
[0021] Usually, the cell structure has at least partially closed cells with
multicornered
base area. The embodiment of the cell structure from in part closed cells
leads to further
reinforcement. The embodiment with different multicornered base areas has the
advantage that the cell structure can be adapted even to complicated
geometries of the
base plan of the bottom plate. Advantageous thereby are three, four, five or
six and
multicornered regular or even irregular shapes.
[0023] In a preferred embodiment, the cell structure exhibits cells with at
least an
areawise round base. Through that, it is possible to equip even rounded base
areas of
the bottom plate with a cell structure. Advantageous thereby is also that the
cell structure
is made from pipes, whereby individual pipe segments are simply joined
together. For
that, circular cylindrical pipes, for instance, can also be used.
[0024] In an advantageous enhanced embodiment, the cell structure exhibits at
least
partially different cell forms. This has the advantage that the strengthening
effect of the
cell structure can be distributed with variations over the bottom plate. This
can be done
for the adjustment of the rigidity in dependence of the load situation. Thus a
cell
structure with many small cells can be used, especially in the regions that
are
particularly exposed to greater stress, for example the borders of the bottom
plate or in
the region of the oscillation excitation. Different cell forms with
complicated geometries
of the baseplate can also be fabricated. Thus, for example, the cell structure
can be
adapted to a drop-shaped cross section of the baseplate.
[0025] Preferably the cell structure has closed cell sidewalls. With that,
high rigidity and
mechanical strength of the cell structure in the respective cell wall planes
is achieved. At
the same time, it enables a continuous welding of the cell structure with the
adjacent
supporting components, such as the bottom plate, the upper plate or the
longitudinal
girders. The welding seams are longer than in an open-celled construction, in
which the
cell walls have recesses in the areas of the feet of the walls. This increases
the firmness
and enables use of thinner cell walls. Thereby the walls of the longitudinal
girders or the
side sheets of the baseplate enclosing the cross section can also serve as
cell walls.
CA 02509069 2005-06-07
WO 2004/053232 6 PCT/EP2003/014012
[0026] In order to achieve a good and uniform load drainage and fabricability
of the cells,
they are so designed that the cells parallel to the base have each the same
form and
area as the base. To be specific, this means that, for instance, the
rectangular cells rnay
have side walls that are arranged at an oblique angle with respect to the base
area, but
the opposite cell sidewalls run parallel to each other. Preferably, the cells
are so built,
that the cell sidewalls are essentially exposed to load due to normal forces.
For that, it is
best if the cell sidewalls are arranged at right angle to the supporting
bottom plate or the
upper plate and from there have a course straight ahead.
[0027] It is not always necessary to support the upper plate exactly like the
bottom plate,
for example, when the cell structure is used only for areawise reinforcement
of the
bottom plate. In that case it is advantageous if the cell structure layout
that does not lead
from the bottom plate to the upper plate, thus enabling further reduction in
weight. In
such a case, it makes sense to have the cell structure that is open above.
[0028] Preferably the cell structure is areawise closed at the top by the
upper plate. This
only areawise covering is done as a rule, if the other components of the
vibrating plate
do not the cover the cell structure at the top. In any case, the cell
structure should
however be protected, possibly through other covers, from infiltration of the
material to
be compacted.
[0029] Independent of this, the upper plate with a solid connection with the
cell structure
leads to further reinforcement of the base plate. The cell structure is also
covered at the
top, so that the material to be compacted cannot accumulate within the cell
structure.
With that the weight of the vibrating plate or the baseplate remains constant
even in an
application of longer duration. Thus, the changes in the weight due to
accumulation of
the material to be compacted cannot lead to changes in the vibration
properties of the
vibration plate. Further, the upper plate facilitates cleansing of the
vibration plate.
Advantageous thereby is a detachable upper plate.
[0030] In another enhanced embodiment, the lower side of the bottom plate is
provided,
at least areawise, with a protection against wear. This has the advantage that
due to the
desired weight reduction, the very thin embodiment of the bottom plate does
not get
obstructed or damaged due to friction with the material to be compacted. Such
a
protection against wear can, for instance, be a coating of a suitable
synthetic material
glued on the bottom plate or even a plastic or a metal plate chucked on the
bottom plate,
which can be easily replaced. The fastening can take place, for example, by
means of
screws, rivets or clamps attached to the baseplate.
CA 02509069 2005-06-07
WO 2004/053232 7 PCT/EP2003/014012
[0031 ] In another embodiment, profile strips are fixed on the bottom plate.
This leads,
on one hand, to further reinforcement of the baseplate and, on the other hand,
to a
profiling of the soil bed. Thereby different profiles, such as for example,
trapezoidal,
triangular or even wave profiles can be used. Here also, the fastening, can,
for example,
be in the form of screws, rivets or clamps or through gluing of the bottom
plate.
[0032] In principle, the vibrating plate itself can be driven and provided
with a grip, so
that it can pushed or drawn, in general vibrating in the known manner, on the
ground by
a single person. It is then called a self-propelled vibration plate. In an
advantageous
embodiment, the vibrating plate comprises, however, an oscillation-proof
suspension for
hooking to a self-propelled support device, which is connected with a
supporting
component of the baseplate. It has to do then with a non-automotive vibration
plate. It is
best if the suspension is connected with the longitudinal girder or through
the cell
structure with the baseplate. Due to the direct connection with the cell
structure, it is
possible to dispense with further fastening elements. The isolation of the
suspension
from the oscillations can thereby take place, for instance, by means of a
rubber or shock
absorber elements, with the result that the oscillations of the vibrating
plate are not
transmitted to the automotive support device. Such an automotive support
device can,
for instance, be a tractor, a snowcap, a road construction vehicle or even a
rolling mill
drive for tilling soil.
[0033] In a further embodiment according to the invention, the driver device
is fastened
at least to a supporting component of the baseplate. Usually, and especially
practically,
the driver device is attached to the longitudinal girder, as already described
above.
Useful are also other forms of embodiments, in which the driver device is
attached
immediately to a possibly specially reinforced cell structure.
[0034] Normally a separate drive is provided for the driver device, for
example a gasoline
motor on the vibration plate. However, in case of an especially light
vibration plate, a
drive arranged on the vibrating plate is dispensed with. Instead, the driver
device can be
coupled on the drive of an automotive support device and can be driven by it.
In that
case, the driver device is driven in the usual manner through a hydraulic or a
mechanical
drive. For that, the driver device is provided with couplers, for example for
the hydraulic
pipelines, or a primary shaft, which can be connected with the corresponding
reciprocal
couplers of the automotive support device.
CA 02509069 2005-06-07
WO 2004/053232 8 PCT/EP2003/014012
[0035] It is of special advantage, if the baseplate has a working width that
essentially
corresponds to its longitudinal side, which is at least so wide as the
automotive support
device. In particular, the working width should be broader than the lane of
the support
device. Thus the vibrating plate smoothens the traces left behind by the
support device,
if the vibrating plate is drawn behind the automotive support device. For that
the
vibrating plate is oriented with its longitudinal side at right angle to the
direction of the
travel. Along the working width, the vibrating plate has compacting action on
the material
lying below it. Due to the especially wide form of the embodiment, it results
in an
especially effective method of working by the vibration plate.
[0036] Especially well suited for the compaction of a heap of debris is a
vibration plate,
the baseplate of which has a cross section, such that the region of the bottom
plate,
which lies at the front in the working direction is bent upwards together with
the front
area of the upper plate. The bending up of the bottom plate in front side in
the working
direction hinders digging in of the plate into the material to be compacted.
Due to the fact
that the upper plate is also bent up, a cell structure can be arranged between
the two
plates. This gives both of these very thin metal sheets, bent upward, good
spatial
stab i l ity.
[0037] In order that the parts of the material to be compacted, that possibly
get
deposited on the vibration plate, also do not accumulate there, the baseplate
(2) has
preferably a cross section, in which the area of the upper plate lying at the
back side in
working direction is inclined with a declining slope inclined with a declining
slope toward
the bottom plate. Thus, the snow or sand rests for example, will simply slide
down from
the back of the surface of the baseplate.
[0038] In the following the invention is explained on the basis of a drawing
of an
illustrative embodiment. Shown schematically are:
Fig. 1 A section A-A through a vibrating plate reinforced with a cell
structure;
Fig. 2 Top view on a part of the vibrating plate shown in Fig 1, with a view
of the
interior cell structure
Fig. 3 Segmentwise view of the section B-B of the vibrating plate shown in
Fig.
1 and Fig. 2
Fig. 4 A cell structure with rectangular base; and
Fig. 5 A cell structure with triangular base.
[0039] Fig. 1 shows in detail the section A-A of a vibrating plate 1 for
compacting and
smoothening of the ski runway. This includes a baseplate 2, which is
reinforced with a
cell structure 5, a driver device 9 for generation of vibrations, and a device
support 10,
which is attached to the automotive support device.
CA 02509069 2005-06-07
WO 2004/053232 9 PCT/EP2003/014012
[0040] In the embodiment shown here, the baseplate 2 contains, as support
components, a bottom plate 3, an upper plate 4, a cell structure 5 lying in
between and a
longitudinal girder 8, which are all made of steel. The driver device 9 is
fastened on the
frame-shaped longitudinal girder 8, which is welded, on its part, on the
bottom plate 3.
The longitudinal girder 8 runs thereby above the entire longitudinal side of
the baseplate
2.
[0041 ] In this embodiment, the cell structure 5 consists of continuous and
orthogonal,
longitudinal cell walls 6 and transverse cell walls 7, arranged mutually at
right angles,
which are welded together firmly with the baseplate 2 and the upper plate 4.
Thereby the
cell walls have wall distance of 50 mm to 150 mm and do not have any openings.
Therefore, it has to do with a close-celled cell structure with high cells,
which have a
cuboid shape in the middle region of the baseplate. In the region enclosed by
frame-
shaped longitudinal girder 8, and along the side sheets 14, the cell walls 6,
7 are
arranged close together, because this region is exposed to especially heavy
stress due
to the driver device. At the same time, the cell structure 5 welded to the
supports 8
stabilizes the supports 8, and thus forms, together with the bottom and the
upper plates,
which are also welded, a light, self-supporting body with high torsional and
flexural
strength.
[0042] In this form of embodiment, the base plate 2 is bent upwards on the
front side in
the working direction, in order to press the snow, which collects before the
vibration
plate, and to be able to slide on unevenness of the soil. In order to support
the 4 mm-
thick upper plate and the equally thick bottom plate, both the plates are bent
upwards
and the interior space lying in between is reinforced with a cell structure 5
made of 3
mm-strong steel sheets. The bottom plate 3 and the upper plate 4 converge
thereby at a
sharp angle to one another, whereby a fold 15 of the bottom plate 3 forms the
pointed tip
of the base plate 2 and, at the same time, a support for the upper plate 4. In
the
backside of the baseplate, the upper plate 4 falls to the bottom plate 3,
whereby a very
narrow fold 16 of the bottom plate 3 forms the rear side support for the upper
plate 4.
[0043] The bottom plate 3 is provided on its bottom side with a protection 12
against
wear by means of an abrasion-proof plastic. The latter is screwed on the
bottom plate 3
and hinders damage to the bottom plate 3, for example due to stones with sharp
peaks
protruding from snow. At the backside of the bottom plate 3, there is a
profile strip 13
mounted below the bottom plate 3, over the entire width, transversal to the
direction of
the direction of travel. It is also mounted in a replaceable manner, and
serves as a
further reinforcement of the end segment of the bottom plate 2, as also for
the profile of
the compacted snow and for the stabilization of the situation of the vibrating
plate during
the sliding on the snow.
CA 02509069 2005-06-07
WO 2004/053232 10 PCT/EP2003/014012
[0044] The vibrating plate 1 is suspended to an automotive support device,
traversing
before it, like a snowcap in this case. For the hooking of the suspension
serves the
device support 10 of the snowcap. It is attached, without modifications in the
support
device, onto the oscillation-proof suspension 11 of the vibration plate 1. The
vibrating
plate 1 does not have own drive for the driver device 9. Instead, the driver
device 9 has
a shaft 18 provided with a coupling 17, with which the driver device can be
coupled to a
drive of the snowcap and then can be driven by it. A hydraulic hose 19, with
the coupling
20, serves to connect the driver device 9 with the hydraulic system of the
snowcap.
[0045] In the top view, shown in Fig. 2, of a part of the vibrating plate
shown in Fig 1, the
variations in the size, form and cross sectional dimensions of the cell
structure 5 can be
recognized. In the region below the driver device 9, the longitudinal cell
walls 6 as well
as the transversal cell walls are arranged close to one another. The border of
the base
plate 2 is also provided with closely arranged transversal cell walls 7. The
remaining
regions of the cell structure 5 exhibit cells, which are built with thinner
longitudinal cell
walls 6 and in which the support walls 8 or the bottom plate 3, which is bent
at the front
and back, form the transversal cell walls 7.
[0046] The cell structure 5 is limited at the side borders of the vibrating
plate 1 by the
sidewalls 14, as it can be seen from the section B-B shown in Fig. 3. In this
embodiment,
the profile strips 13 have a trapezoid profile for fabrication of a corrugated
runway
surface. The oscillation-proof suspension elements 11 are arranged in this
illustration of
the embodiment between the multicomponent driver devices 9 and are connected
directly with the cell structure 5.
[0047] (n the Figures 4 and 5, two sections from the two different cell
structures 5 are
shown, whereby the cell shown in Fig. 4 has a rectangular and orthogonal base
area
and the one shown in Fig. 5 has a triangular area. The maximum lateral
extension 22 of
the base 23 enclosed by the cell walls 6 and 7 corresponds in Fig. 4 to the
distance of
the outer sides of the mutually opposite cell side walls 6, which are
farthermost from
each other. In Fig. 5, the maximum lateral extension 22 of the base area 23 is
the
outside length 22 of the third and the longest cell wall 21, tying diagonally
in this case. In
the example of the cell shown in Fig. 4, it means, to be specific, for cell
wall thickness of
3 mm and the open wall distance between the two mutually opposite cell
sidewalls 6 of
50 mm thickness, that the maximum lateral extension 22 of the cell has a value
of 56
mm. Therefore, in case of a cell with a pipe-shaped base, not shown here, the
maximal
lateral extension corresponds to the inner diameter plus the twice the wall
thickness of
the cell walls.
