Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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BASE PLATE, IN PARTICULAR FOR
PREPARATION OF CONCRETE PRODUCTS
BACKGROUND OF THE INVENTION
l. Field of the Invention
The invention rela-tes to a base plate and particularly
a plate for use in production of concrete products.
2. Description of the Related Technology
As show in Fig. 1 and 2, an empty base plate 20 taken
from a plate storage 30 is introduced into a molding machine 10
during production of concrete products (composite blocks,
plates, blocks, curbstones. The molding machine 10 includes a
vertically movable mold ll, a press plunger 12 and a die plate
13. The base plate 20 is placed onto a vibrating table 14,
which may be vibrated by an eccentric wheel or cam 15 or the
like. Following the insertion of the base plate 20, the mold
11 is lowered onto the plate 20 and filled from above with a
mixture of cement and sand. The mixture is then densified by
the pressure of the press plunger l~ lowered from above and the
vibration of the table 14. Subsequently the press plunger 12
and the mold ll are ràised and the plate 20, with the molding,
is pushed from the molding machine 10 onto conveyer rails 40.
The plate 20 and the molding, are optionally moved by a
stacking carriage 50 to a drying room 60 on. The molding is
hardened in the drying room 60 conveyor rails 40. In a
discharge station 70, the hardened molding is taken as a
finished concrete product 80 from the base plate 20. The base
plate is then returned to plate storage 30 for drying.
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If the base plates are equipped, on their bottom side,
with stacking feet the base plates 20 may be stacked directly
on rails in place of a stacking carriage 50. In this case, the
mutual distance of the stacking feet is sufficiently large so
that when stacked a lower molding fits between the stac~ing
feet of a plate 20 stacked above the lower molding. The
bending rigidity of the base plate 20 must be high even when in
extended storage and with the potential application of drying
heat as the loaded base plate 20 rests on only two border areas
on rails 40, the rails of the stacking carriage 40, the control
rails of the drying room 80 or on stacking feet- If the base
plate 20 is not entirely flat, hair cracks will develop during
the hardening of the hardened concrete-sand mixture which
render the finished concrete product useless.
Solid wood plates have been used heretofore to satisfy
the aforementioned requirements of high base plate bending
rigidity. The plates were assembled of individual planks,
drawn together with steel reinforcing bars and protected on the
frontal sides with metal profiles. As the wood, Spruce, larch
or tropical hard woods have been used, with dimensions of 1400
mm x 900 mm x 50 mm, variable depending on the surface area
required and on the strength of the wood used (hard or soft
wood). Due to their assembly from individual planks, wooden
base plates have joints at the contact locations of the planks
which interrupt the smoothness of the surface- Surface-changes
also occur over time due to the unavoidable abrasion and
climatic effects on the wood. Furthermore, wooden base plates
must be carefully maintained (regular oiling or spraying with
impregnatlng agents and regular turning, so that both surfaces
are used), in order to extend their useful life over a period
of 2 to 5 years (depending on the type of wood)~
The replacement of wooden materials by a plastic has
been heretofore unsuccessful because the plastics considered
suitable for high loads would be significantly more expensive
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than wood. The increasing public criticism of the destruction
of tropical rain forests further converts the use tropical hard
woods into an environmental problem, whch cannot be solved by
the exclusive use of the spruce and larch wood, as soft woods
may be used up to certain loads only.
SUMMARY OF THE INVENTION
It is an object of the invention to create a base
plate, which provides a permanent smooth surface requiring no
maintenance even under very high loads, without being
appreciably more expe.nsive than conventional base plates.
This object is attained according to the invention by
a base plate prepared from contaminated plastic wastes composed
of between 70 and 90% polyolefins by weight, between 0 and 15%
polystyrene by weight, between 0 and 10% polyvinylchloride by
weight and a residual proportion of other plastics and
contaminants, plasticizing and extruded in the thermoplastic
containing plastic components.
The material may include fiber-containing material is
added in a loose or continuous form. The fiber-containing
material may be glass, wood, textile and/or plastic fibers,
The fiber containing material may be added in the form of a
fabric, a knit or a mat. According to the invention, the edge
zones of the body of the plate may exhibit embedded reinforcing
pipes or rails. Alternatively, the plate may exhibit surface
mounted reinforcing rails on the plate edges. The height of
the reinforcing rails may be equal to or smaller than the
height of the body of the plate. The reinforcing plates may
have an essentially C shaped profile. Free ends of the C
shaped profiles may include hook like projections cast into the
body of the plate.
According to a further feature of the invention,
stacking feet may be molded on the bottom side of ~:^~ body of
the plate, or on both the top and bottom side.
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The base plate according to the invention may be
produced from recycled plastic materials in a single piece and
may optionally include molded stacking feet. Abutting joints
and other changes in the flat surface, such as those found on
wooden base plates, are eliminated. Furthermore, no
maintenance is required and unlimited storage period are
possible. The abrasion strength of the recycled plastics is
considerably higher than that of wood, which altogether results
in a significantly longer useful life than that of wooden
materials. The utilization of plastic wastes as the raw
material rather than tropical hard woods render the base plate
of the invention especially friendly to the environment. The
production costs of the base plate according to th~ invention
are comparable with or even lower than those of wooden plates
due to the use of plastic wastes as the initial material. The
base plate according to the invention has been found highly
suitable in view of the aforementioned advantages.
BRIEF DESCRIPTION OF THE DRA~INGS
Figure 1 shows a block diagram of a production plant
for composite concrete blocks and plates.
Figure 2 shows a schematic view of a molding machine
in the plant according to Fig. 1 for the production of
composite concrete block and plates.
Figures 3a-3d show perspective cross sections through
four different embodiments of a base plate according to the
invention, used in a production plant accordin~ to Figure 1 and
inserted into the molding machine according to Figure 2.
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DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The production plant according to Figure 1 and the
molding machine 10 according to Figure 2 are already explained
in the preceding introduction- The base plate 20a shown in
Fig. 3a includes of a prism shaped plate body, produced
according to the preferred embodiment essentially from
contaminated plastic wastes (recycled plastics). The plastic
wastes contain a high proportio~ of thermoplastics, which when
charged into an extruder, in particular a roll extruder with
inlet, compression and metering zones according to
DE 2,332,803, are melted essentially by the heat o~ friction
and homogenized. The non-melting proportion of the plastic
wastes charged in a comminuted form, is further comminuted or
ground and is incorporated in the thermosplastic mass in the
form of granules. The plastic melt exiting from the extruder
(together with thP residual non-melting granules embedded in
it) is filled into a plate mold and hardened therein.
Corresponding to the material system described abo:e
for the production of plate bodies, plastic wastes are used
with the following composition:
70-g0% by weight polyolefins,
0-15% by weight polystyrene,
0-10% by weight polyvinylchloride, and
residual components of other plastics and impuritie
Although in many cases such a base plate made of
recycled plastics has adequate mechanical properties, in
particular an adequate bending strength, fiber containing
material may be added to the plasticized plastic mass before or
during the filling of the plate mold, in a loose, irregular
form. The fibers 21 (Fig. 3a) are then present in the plate
cross section in a random distribution, which improves the
mechanical strength, in particular the bending rigidity. In
order to improve the b~nding properties of the plate 20a even
more specific~lly it is also possible to provide the fibers
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only in zones of the plate subject to a high mechanical stress
or to enrich them in these zones. The concentration of the
fibers 21 is such that all of the fibers 21 are embeddced in
the thermoplastic material, in order to create an active
combination with said thermoplastic materials in the sense of
an increase in mechanical properties.
In place of or additionally to the loose fibers, such
materials may be added in a contiguous form. The materials may
be embedded in the form of a fabric designated 22 in Fig. 3b,
or a knit or a fiber mat, into th~ mass to produce a base
plate. The fiber layer (fabric, knit or mat) 22 in Fig. 3b is
located in the neutral bending zone, i.e. in the center plane
of the base plate 20b.
The fibers, in all embodiments (Fig. 3a, 3b) may be
glass, textile, natural or plastic fibers may be used. Suitable
natural fibers are wood or sisal fibers. The length of the
fibers should be coordinated with the strength of the plate
desired.
Additionally to or in place of the addition of fibers
according to Fig. 3a and 3b, the strength of the base plates
may be increased by embedding reinforcing pipes or bars 2s
(Fig. 3d) in the body of the plate or by casting reinforcing
rails onto longitudinal edges of the body of the plate. In the
embodiment according to Fig. 3d, the reinforcing pipes 25 are
located parallel to the longitudinal edges o the plate body.
The reinforcing pipes may be provided at least in the area of
the edge zones of the plate body. In the embodiment shown in
Fig. 3d, an additional reinforcing pipe or rod 25 may be
provided in the longitudinal axis of the plate body. The
number of reinforcing pipes or rods 25 and their diameter
depend on the thickness of the plate body and the mechanical
properties desired of the finished base plate 20d. In any
case, care must be taken that the reinforcing pipes 25 are
surrounded sufficient thermoplastic materials in order to
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insure an active connection between the thermoplastic material
and the reinforcing pipes. As the material ~or the reinforcing
pipes, structural steel is preferred, with the pipes 2s
provided in the a solid or a ho].low shape. In the case of
hollow profiles thermosplastic material may be poured into the
reinforcing pipes.
In the embodiment according to Fig. 3c, the
reinforcing pipes or rails 23 located on the longitudinal edges
exhibit an essentially C-shaped profile. The free ends of the
C profile may be provided with hook like extensions 23e to
anchor them on the body of the plate. The reinforcing rails 23
may be inserted during the molding of the plate body into the
mold and cast in, so that they are positively connected to the
thermoplastic material of the plate body, thereby enhancing the
mechanical properties of the latter. The thickness (height) of
the plate body may be chosen so that the top and bottom side of
the finished base plate 20c projects past the top and bottom
sides of the reinforcing rails 23, as shown at an enlarged
scale in Fig. 3c. This projection of the plate body insures
that only the plastic surfaces of the base plate 20c are active
in the production of concrete products.
Integral stacking feet may easily be molded together
with the plate bottom side or bottom and top side of the plate
body in casting in all of the embodiment according to Fig. 3a
and 3c as shown in Fig. 3c. This eliminates the step of
screwing stacking fest on to wooden plates. The stacking feet
contribute to the increased mechanical strength of the base
plates 20a to 20d as the result of their single piece molding.
It is possible to use the base plates for purposes other than
production of concrete products, for example as transport
pallets or cladding plates, such as those used in construction.
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