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Description  |
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CROSS REFERENCE TO RELATED APPLICATIONS
This is a national phase application corresponding to PCT/DE 92/00425 filed
May 21, 1992 and based in turn upon the German application P 41 25 889.4
filed Aug. 5, 1991 under the International Convention.
The invention relates to a device as well as a method for temporary
attachment of holding or fastening means to a surface having
irregularities, whereby the vacuum principle used in suction attachments
is applied.
BACKGROUND OF THE INVENTION
There are known devices having a suction attachment connected to a vacuum
pump and which is applied to workpiece in order to be used as load hook.
Further known are suction attachments in connection with drilling devices,
whereby these suction attachments serve as equipment holders (DE 35 01
753, DOS 27 44 463). From French Patent 1 595 727 a suction cup with a
compressible pad made of porous rubber is known.
Finally, vacuum holding devices are known which work with plate-shaped or
cup-shaped suction elements, which on the side facing away from the
workpiece to be held are provided with sealing lips or a sealing ring,
whereby the latter is made of a very soft, elastically deformable material
and is designed as special, separate part and connected with the suction
element (DE-AS 27 23 16).
The task of these known devices is to hold or to transport loads, such as
drilling equipment. A precondition for the acceptable operation of these
devices is a basically even, smooth, dense and homogeneous surface of the
load to be transported. The suction elements known from DE-AS 27 23 616
and French Patent 1 595 727 can also be used on a substrate which is not
completely even, but provided a predetermined negative pressure is
constantly maintained.
OBJECTS OF THE INVENTION
It is the object of the invention to provide a device based on the vacuum
principle for the temporary attachment of holding or fastening means which
can be affixed to a surface having irregularities and/or which is
inclined;
Still another object is to provide such device that continues to have
sufficient holding power after the negative pressure has been reduced or
eliminated; and
Yet another object is to provide a method for mounting the device according
to the invention.
SUMMARY OF THE INVENTION
Such tasks have to be frequently performed not only in industry, trades,
but also in private life. For instance, in construction it is a matter of
creating support for a concrete encasing, of fastening scaffolding, of
affixing a mounting on an inclined roof surface or simply of securing a
freely set cable in several points at a corresponding height.
In order to solve this problem, the invention stems out from such a known
device as described in French Patent 15 95 727. The device consists of a
mounting plate traversed by vacuum passages and bearing on one side the
holding or fastening element, and of other side of the plate which serves
sealing purposes and is provided with a closed roll of compressible
material.
According to the invention, the mounting plate is designed as a
plane-parallel and stiff holding plate, on whose sealing side a roll is
applied as a plastically deformable sealing mass.
Thereby it is advantageous to use a corrosion-resistant plastic material
with surface adhesion for the holding plate, whereby polypropylene proves
to be particularly suitable as a plastic material.
This holding plate can have one or more vacuum connections running in the
plane of the plate or vertically to the plate plane. In the first instance
they run as channels ending in suction openings. Several vacuum
connections in such the plate offer the possibility to create several
vacuum chambers by mounting several closed rolls of a plastically
deformable sealing mass, therefore limiting the unsealed areas of the
substrate.
In order to maintain a sufficient volume of vacuum when the holding plate
is affixed to an uneven surface, it is advisable to insert one or more
limiters in the sealing side of the holding plate as spacers with its
length suitably adjustable. For this purpose it is possible to insert in
the holding plate an inner thread consisting of metallic parts, which, for
instance, would serve for receiving the spacers. Such inner threads can be
provided also on the outside of the holding plate, for optional fastening
of holding elements.
Furthermore the sealing side of the holding plate can be provided with a
surface structure enhancing the adhesion forces. For instance this surface
can be provided with milled ribs or simply be sandblasted.
Finally the holding plate can be provided with lateral grip ledges, which
would facilitate its application onto and removal from a substrate. These
grip ledges or optionally additional recesses can serve for the
application of a corresponding tool for the removal of the holding plate.
As the plastically deformable sealing mass of the holding plate
polyisobutylene is used, whose characteristics are ideal for the present
purpose. This plastic material, for instance in the form of a roll, is
placed around the rim of the holding plate and is easily pulled off the
uneven surface as well as the holding plate, without leaving residues.
This way this material can be used again repeatedly when such a holding
plate is used. When vacuum is created between the holding plate and the
surface, it has the particular feature of fitting itself vacuum tight to
the irregularities of the latter. Besides, as a result of its excellent
adhesion characteristics a surprising effect results in that even after
the elimination of the vacuum existing between the holding plate and the
uneven surface, the holding plate remains attached under load for a longer
period of time, sometimes up to weeks. This holding or adhesive effect can
even be permanent. This surprising effect represents an essential
advantage over the previously mentioned known suction attachments, which
work with sealing lips or sealing rings of rubber or a rubber-like
material, as well as over the ones provided with a roll of compressible
elastic material according to French Patent 15 95 727. In these known
suction attachments, when the vacuum is eliminated, the object carried by
the suction plate falls down instantly.
Nor is the invention obviated by DE-OS 34 25 853 which teaches how to
produce mountings or hooks on an even wall by generating a vacuum between
the mountings and wall and by subsequently injecting sealing masses. This
known mounting can carry a load only after the sealing mass has hardened
and therefore does not solve the problem of the invention.
The plastically deformable sealing mass can have its profile preshaped
before it is attached to the holding plate. For producing a preshaped
profile an extruder can be used. This profile can be shaped like sealing
lips in order to achieve a quick sealing. The application of the extruded
profile onto the holding plate is thereby facilitated by a guide element
which is guided along in a groove of the holding plate.
It has already been mentioned that the sealing mass can be applied as a
closed rim in the desired shape. This shape can be selected so that
unsealed areas of the substrate can be excluded. The amount and cross
section of the sealing mass can be adjusted to the respective purpose of
use, in order to achieve the respective desired adhesion force.
Depending on circumstances the sealing mass can be selected from so-called
polar masses (used between -30.degree. to +5.degree. C.), standard masses
(used at 0.degree. to +40.degree. C.) and tropical masses (used between
+15.degree. to +70.degree. C.). A combination of these masses are also
possible. With the assistance of pressure or suction, the introduction of
liquids or gases of various temperatures is advantageous for easy assembly
and disassembly.
An essential advantage resulting from the use of a plastically deformable
sealing mass consists also in the fact that it is self-sticking and can be
affixed onto an uneven surface even before generating vacuum--by
mechanical contact pressure--since indentations occur between the sealing
mass and the uneven surface.
The use of plastically deformable sealing masses offers such a further
advantage as the vacuum sealing of the holding plate can be fixed at any
time with additional sealing masses, if there are still unsealed spots.
The use of thinned glue or paste can make advantageous substrates
airtight, without thereby noticeably changing the substrate.
In order to enhance safety and for an easier supervision of the device of
the invention it is proposed to provide an optic or acoustic alarm
triggered by the failure of the vacuum generator, i.e. due to current
interruption or when the vacuum decreases due to other reasons.
A further improvement of the device of the invention consists in the fact
that an additional vacuum tank with a sufficient vacuum chamber is
provided, which is interposed between the required vacuum pump and the
vacuum duct traversing the holding plate. This vacuum tank, which has a
cylindrical shape and is provided with one or more perforated intermediate
walls or with external peripheral ribs for reinforcement, maintains the
vacuum over a longer period of time, even after the vacuum pump was turned
off. This vacuum tank is supposed to be equipped with a fluid meter as
well as with a discharge valve for the aspired fluid.
BRIEF DESCRIPTION OF THE DRAWING
The above and other objects, features, and advantages will become more
readily apparent from the following description, reference being made to
the accompanying drawing in which:
FIG. 1 is a top sectional view of a holding plate according to the
invention;
FIG. 1a is a rear sectional view of this holding plate;
FIG. 2 is a lateral view of the holding plate assembled on the wall;
FIG. 1b is the holding plate affixed to a wall;
FIG. 2a is a cross sectional elevated view of another embodiment of the
holding plate according to the invention;
FIG. 2b is a frontal view of the plate seen in FIG. 2a;
FIG. 3 is a sectional view of a further embodiment of the holding plate,
assembled on the wall;
FIG. 4 is a longitudinal sectional view of an additional vacuum tank;
FIG. 4a is a longitudinal sectional view of an additional vacuum tank
according to another embodiment of the present invention;
FIG. 5 is a top view of the vacuum tank shown in FIG. 4a;
FIG. 6 is a diagrammatic view of the holding plate according to the
invention mounted to hold a work platform;
FIG. 7 is a diagrammatic view of the holding plate according to the
invention along with the assembly of finished construction components;
FIG. 8 and FIG. 9 are diagrammatic views of the holding plate according to
the invention mounted to hold protection scaffolding;
FIG. 10 is a diagrammatic view of the holding plate according to the
invention and supporting framework for single-headed casings;
FIG. 11 is a diagrammatic view of the holding plate according to the
invention mounted on an inclined storage surface (clarifying basin), and;
FIG. 12 is a diagrammatic view of the holding plate according to the
invention used to hold traffic signs.
SPECIFIC DESCRIPTION
The basic principle of the invention results for instance from the
illustrations according to FIG. 1 and 2. These figures show the holding
plate 1 which is made of a light-weight plastic material which does not
distort, shrink, corrode or absorb humidity. This holding plate 1 of
plastic material is pressed against the substrate 7 having an uneven
surface by providing an intermediate plastic sealing mass 5 which has been
previously applied to the backside of holding plate 1 along its edges. In
order to maintain a predetermined volume of vacuum between the holding
plate 1 and the substrate 7, through the holding plate 1 one or more
longitudinally adjustable dividers 3 traverse the plate in a vacuum tight
manner and rests against the substrate 7. Further the holding plate 1 has
passages for a vacuum gauge 4 as well as for a vacuum hose connection 6.
Further the holding or fastening means 2 can be seen on the outside of the
holding plate 1.
This holding plate has a size of approximately 30.times.30 cm and a
thickness of 3 to 5 cm.
If such a holding plate 1 is pressed against a wall with rough finish, all
that has to be done is to establish and maintain a vacuum between the
substrate 7 and the holding plate 1 through the vacuum connection 6, in
order to be able to use the holding and fastening means 2 according to
their purpose. With the aid of a vacuum pump a vacuum of approximately
-0.7 or -0.8 bar is generated, which can be read on the vacuum gauge.
FIG. 1a shows a rear view of the holding plate 1 represented in FIG. 1 with
the plastic sealing mass 5 applied to its rim. Besides a bar 5a provided
on this backside is shown, which facilitates the application of the
plastic mass 5 on the rim area of holding plate 1. Under certain
circumstances, this bar 5a can make the divider 3 superfluous.
FIG. 1b shows the fastening of holding plate 1 to unplastered brickwork.
Since the individual bricks consisting of an airtight material are
separated from each other by air-permeable gaps, first several rolls 1c of
a plastically deformable material are applied to the sealing face of
holding plate 1, so that after the holding plate 1 is pressed against the
brickwork 7 a corresponding number of vacuum chambers can be established.
For this purpose suction openings connected with these vacuum chambers are
connected with the laterally mounted vacuum connections 6a.
In FIGS. 2a and 2b a holding plate of different execution is shown in cross
section and in a frontal view. Its sealing face is provided with a surface
41 which has been roughened by milling or sandblasting, this way
contributing to the enhancement of the adhesion forces. Besides in the
representation in cross section according to FIG. 2a a gripping bar 40 can
be seen, which serve for an easier handling of the holding plate.
In FIG. 3 a further embodiment of the device of the invention corresponding
to FIG. 2 is represented, which affords increased safety. In this case the
holding plate consists of two interfitting plates 1a and 1b, which form
separate vacuum chambers with the substrate or wall 7. The vacuum chamber
between the holding plate 1a and the wall 7 is defined by the plastic
sealing mass 5a, the vacuum chamber between the holding plate 1b and the
wall 7 is defined by the plastic sealing mass 5b. Both vacuum chambers are
connected to separate vacuum generators, so that for instance when the
vacuum generator assigned to holding plate 1a fails, this holding plate 1a
continues to be held by the holding plate 1b.
In FIGS. 4 and 5 an additional vacuum tank 8 is shown, whose vacuum chamber
is connected in series via vacuum hoses with the vacuum generated by the
devices shown in the preceding figures. This vacuum tank consists of a
plastic tube which is closed in a vacuum tight manner on both ends by
cover plates 9. These cover plates 9 are again sealed with the plastic
sealing mass 12. In order to keep up its buckling resistance this plastic
tube is provided with one or more perforated dividing walls 10, which are
also kept in place by the plastic sealing mass. The sealing points are
marked 12, the holes are marked 11. The cover plates 9 of this vacuum tank
8 have connections 13 for the vacuum line, further there is a vacuum gauge
14 in one of the cover plates.
A modified embodiment of such a vacuum tank 8a is shown in FIG. 4a. In
order to achieve sufficient buckling resistance, this tank 8a is provided
with peripheral external ribs 42. In addition, this tank is provided with
a display fixture 43 showing the level of aspired liquid, as well as with
a liquid valve 44 for the evacuation of the aspired liquid. It would be
suitable to provide these fixtures also in the embodiment of FIG. 4.
Depending on their purpose, such vacuum tanks as shown in FIGS. 4 and 4a
can have a height of 50 cm to 5 m, a diameter of 10 cm to 50 cm and a wall
thickness of 7 to 12 mm.
In FIGS. 6 to 12 embodiment examples for the use of the device of the
invention are shown, whereby identical or corresponding parts are marked
with the same reference numerals as in the preceding figures. In these
shown examples only the mounting of the holding plate is partially shown,
without the required implements for the vacuum generation or maintenance.
As a rule there are always pertaining vacuum generators, a special
supplementary vacuum tank, a vacuum switch and the required vacuum lines,
which have not been illustrated for the sake of simplicity. Thereby the
vacuum switch has the task to automatically turn on the vacuum generator
(and also to turn it off again) when the vacuum surpasses a certain
preselected value.
However, in this connection it has to be pointed out that for a temporary
attachment of holding or fastening means to an uneven or inclined wall it
is not absolutely necessary to include a vacuum generator in the circuit.
It can be absolutely sufficient to connect the vacuum passages through the
holding plate with a vacuum tank under vacuum, after the holding plate has
been affixed to the uneven wall, as shown in FIGS. 4, 4a and 5. The vacuum
contained in this tank is then sufficient for the evacuation of air
contained in the space between holding plate and the wall with uneven
surface, thereby strongly pressing the holding plate against the wall.
Now in FIG. 6 one wall 7 is shown, which can be for instance a shaft wall,
a staircase or a tank wall having an extraordinarily uneven surface. To
this uneven surface a work platform 15 has to be affixed. This is takes
place with the holding plate 1, which is first coated in the
aforedescribed manner with the plastic sealing mass 5 and then pressed
against the wall 7. Then over the vacuum connection 6 the vacuum is
produced in the intermediate space. The holding means consist in this case
of carrier plate 16 fitted onto the holding plate and wherein next the
square timber 17 and thereon the deals 18 are positioned.
In FIG. 7 it is shown how the invention can be applied in the assembly of
finished parts, providing assistance for directional accuracy. In this
case two holding plates 1 are used which are fastened on the one side to
the foundation anchor block 19 and on the other side to the support 20 for
the finished concrete component and which in turn are connected by a
screw-adjustable support 21. The vacuum chambers underneath these two
holding plates 1 are connected via vacuum hoses 23 to the vacuum tank 8,
which in turn is connected via vacuum line 27 with the vacuum generator
26. The vacuum generator 26 is controlled by vacuum switch 24; the network
connection is marked 25.
In this embodiment example all devices for vacuum generation and vacuum
maintenance are used twice.
In FIGS. 8 and 9 two embodiment examples are explained, which also pertain
to the field of construction. In FIG. 8 a brick wall is shown, which is
covered by a rough finish 28. The holding plate 1 is set against this
roughly finished wall, this plate being supposed to carry in turn the
scaffolding console 30 with the work surface 29. In this example the
holding plate 1 with the scaffolding console 30 and the work surface 29
form a unit, which at the same time carry the vacuum tank 8 as well as the
vacuum generator 26 and the vacuum switch 24. Via vacuum line 23 the
vacuum generator 26 is connected with the vacuum passages of the holding
plate 1. This described unit can be transported as a whole and can be used
as such at any desired construction site.
The construction shown in FIG. 9 is similar, it differs from the
construction in FIG. 8 in that a total of two holding plates 1 are
provided, which form a constructive unit with the scaffolding console 30
and the work surface 29, as well as with the other shown devices.
Finally FIG. 10 shows the fastening of the support framework 34 with the
aid of the holding plate 1 of the invention. On an existing building 31
after an insulation 32 a concrete wall 33 has to be erected, and for this
purpose it is necessary to install the support framework 34.
FIG. 11 shows how the invention can be applied in a clarifying basin which
has inclined concrete walls, to which frame supports have to be affixed
with the aid of the holding plate of the invention.
The embodiment example according to FIG. 12 illustrates the erection of
traffic signs 36 which are supposed to be affixed to the asphalt so that
they rest securely on their base. The holding plate 1 of the invention is
again used in this instance in accordance with the representation in the
drawing.
It has already been mentioned that the invention finds application
possibilities in industry, trade or in private life. So for instance the
vacuum holding plate of the invention can be used as a cable holding
plate, shop accessories holding plate, as a holding plate for clothes, as
a drilling devices holding plate, as a holding plate for diamond cutting,
as a holding plate for light sources, as a holding plate for measuring
instruments, a holding plate for filming and photo cameras, for shows and
fairs, as advertisement displays for images, inscriptions or sensors, for
antennas or receivers, as a holding plate for wall and ceiling recesses,
for sealing against liquids, fresh concrete or fresh plaster.
Further utilizations would be holding plates for cantilever scaffolding,
overhung constructions, for securing to facade walls for purposes of
cleaning or inspecting parts of the facade wall, for roofing work, as a
bannister post holder, holding plates on concrete supposed to be covered
with wall hangings and where drilling is not allowed, as securing plates
for cable attachment and further as securing plates in assembly
operations.
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