Note: Descriptions are shown in the official language in which they were submitted.
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PROCESS OF MANUFACTURING INTERMEDIATE
CONCRETE PRO~UCTS, FORM FOR ~L~NUFACTURIN~ SAID PRODUCTS,
AND APPARATUS FOR CARRYING OUT SAID PROCESS
The present invention relates to a process or manufacturing
intermediate concrete products, sUch as tiles, to a form for manufacturing
said products and to an apparatUs for carrying oUt said process.
In building construction, roofing tiles made of clay or concrete are
used. Since, ln a primary sense, the production of clay tiles is locally
restricted to areas where a basic stock of raw materials exists, and
preferably to large stationary plants characterized by high power
consumption on production, there are used more and more concrete tiles
uhich correspond to clay tiles, both in form and quality.
The concrete tiles are manufactured according to a known process in
such a manner that Concrete of dry to damp consistency, having as a rule no
additional dyes, is fed onto a horizontal form and consolidated into the
correspondin~ form by means of vibrating and compressing. Further, raw
tile formed in such a manner proceeds into a heating chamber in which there
prevail specified climatic conditions (humidity of 95~ and temperature of
up to 65 C) and reposes there until achieving approximately 50~ of its
ultimate strength. Only then can the tile be lifted out of the horizontal
form for further treatment, e.g., sorting, colouring, storage.
Due to the technologic~l characteristics of concrete of dry to damp
consistency, there exists, with the known process, a problem of how to
attain good homogeneity and mixing of the components of the concrete,
particularly those which appear in small quantities (from 0.5% to 5~ by
veight of cement) in a concrete mixture This problem is particularly
obvious in chemical admixture for improving the strength of the concrete
product and in adding dyes to the concrete mixture. Said problems result
in a variable quality of product, both in a technological and in a visual
sense. A disadvantage of the concrete of said consistency is also a
relatively high sensitivity to changes in volume in loose and consolidated
states, which results in a change of quality of the product, even with the
slightest change of input material, e.g., humidity.
A further disadvantage of the kno~n process lies in a high sound
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pressure level occurring when consolidating the concrete by means of
vibration. Due to intensive vibrating of the concrete, there also appear
powerful vibrations in the surrounding tile producing machinery. During
consolidation of the tiles, deformation of the horizontal metal forms takes
place, which results in the necessity of frequently replacing the forms to
avoid deformed products.
Another disadvantage of the known process lies in the fact that the
side of the concrete product - tile facing away from the form is open,
i.e., unprotected, wherefore damages can occur to the tile. During the
time in which the tile lies in the chamber, even the entire surface of the
tile which, in use, is exposed to the weather, can be damaged due to
possible changes in humidity or temperature.
A further disadvantage lies in the fact that a great amount of space
is needed for the aforementioned process for manufacturing tiles, as the
daily production of, e.g., 100,000 tiles, requires approximately 12,000 m3
of room which, in addition, should be heated to a temperature of
approximately 65 C, which results in a relatively high power consumption.
The present invention provides a process for manufacturing concrete
products, preferably tiles, in which the aforementioned disadvantages can
be eliminated.
The invention can also provide a form for manufacturing concrete
products, preferably tiles.
Also, the invention can provide an apparatus for carrying out said
process.
Other features of the process and form for manufacturing the
intermediate concrete products, as well as of the apparatus for carrying
out the process according to the invention, are evident from the disclosure
below. It is understood that the present invention can be used for
different intermediate concrete products too, although it is specifically
described for the manufacture of concrete tiles.
The invention is further described in the following preferred
embodiment, reference being made to the accompanying drawings, wherein:
Fig. 1 is a schematic diagram of an apparatus for carrying out the
process according to the invention:
Fig. 2 is a side elevation of a charging head of an apparatus
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according to the invention;
Fig. 3 is a view of the charging head of Fig. 2;
Fig. 4 is a vertical sectional view of the charging head:
Fig. 5 is a view in the direction of an arrow V oi Fig. 4;
Fig. ~ is a detail of a blocking unit in closed position:
Fig. 7 is a detail of a blocking unit in open position:
Fig. 8 is a plan view of a form for manufacturing tiles according to
the invention:
Fig. 9 is a sectional view of a form taken along the line IX-IX of
Fig. 8: and
Fig. 10 is an element of a form according to the invention.
The feature of the present process according to the invention lies in
the use of concrete of a casting consistency, which ensures uniformity of ;,
the composition and unsegregatability of the concrete, the possibility of -
forwarding under pressure to the charging head and filling up a row of
forms during one production cycle with exact material dosing. Cast
concrete possesses the features of good and quick homogeneity, even in the
ca~e when very small quantities of chemical or mineral additives are added.
Thus, by obtaining a high degree of uniform quality, there iS ensured the
durability of the material, e.g., resistance to freezing and chemical
influence, and a high quality of pigmentizing of the concrete mass.
Components of the cast concrete, ensuring the necessary characteristics oi
the fresh concrete admixture, are as follows:
- cement, preferably highly active cement:
- stone aggregate with size gradation of at most 3.2 mm and sifting of
15~ to 202 through a 0.25 mm sieve;
- known chemical admixture for lowering the surface tension of the
~ater:
- known chemical admixture for introducing microporosity into the
cement paste:
- mineral fine-grained admixture for preventing micro-mixing (micro-
segregation) of concrete and decreasing permeability of the concrete
admixture to water:
- mineral fine-aggregate admixture for volume reduction of concrete
mass:
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- water; and
- mineral dyes.
The process according.to the invention will be further described in
detail referring to Flg. 1 showing a schematic diagram of an apparatus for
carrying out said process. Concreta of ~he aforementioned composition and
consistency is prepared in a known counterflow concrete plant. Concrete
prepared in SUCh a manner is delivered into a storage bin 1 o~ a screw pump
2, by means of which it is conveyed through a pipe line 3 to a charging
head 4 of an apparatus according to the invention. In the given case, the
charging head 4 is arranged for filling up a row of forms 5 whereby
concrete is contractionally discharged into each form 5 by means of
discharging nozzles 6. Pressure required for operation of the system is
maintained by means of automatic synchronized working of the pump 2 and of
the unit for opening and closing the stops and unit for lowering and
liftine the head 4, whereby it is particularly important that in all
nozzles 6 for filling up the forms 5 the same pressure is ensured. Its
value at the outlet of each nozzle 6 equals from 0.1 bar to 0.5 bar,
preferably 0.2 bar. Due to the characteristics of concrete, said forms
must be water-impermeable and made of thermally insulating material, e.g.,
polyurethane resin. Each nozzle 6 of the charging head 4 is thrust to the
area of the bottom of each form 5 and then concrete is conveyed therein.
When the form 5 is fllled essentially one third in height, the charging
head 4 and the nozzles 6 are lifted up with a constant velocity until the
forms 5 are completely filled. The nozzles 6 should not be lifted over the
level of the concrete being cast. The lifting velocity of the charging
head 4 and thereby of the nozzles 6 is adjusted to the largest cross-
section of the product being cast, and in this particular case equals from
0.05 ms~l to 0.2 ms~l, preferably 0.1 ms~l.
When the forms 5 are filled up, they are transferred to a setting
location. As said forms are made of thermally insulating material, the
intrinsic heat energy of hydration of the cement that is released is
exploited during the setting of the concrete. In such a manner, the
concrete is aBed practically in adiabatic conditions and, after
approximately 24 hours, reaches a temperature of approximately 55 C above
ambient temperature which, in this particular case, was 20 C, without
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additional heating whereby any further thermal treatment is superfluous.
Figs. 8, 9 and 10 show a form 5 for casting concrete tiles. Said forM
comprises a pair of frames 7,8 clamping together a plurality of elements 9
made of water-impermeable and thermally insulating material, e.g.,
polyurethane resin, the form of which corresponds to a product desired and,
in this particular case, corresponding to a tile. Each element 9 is, along
both vertical sides, provided with a pair of enlargements 10,11 w~ereby
facing sides of each enlargement 10,11 of two adjacent elements 9 are
parallel, abutting slitlessly, each other. The element 9 is at its first,
in this particular case, its lower, end provided with a web 12 being
essentially perpendicular to said element and running between the
enlargements 10,11. In the form assembled to a block of elements 9, said
web slitlessly rests against the adjacent element 9 forming a bottom 13 of
the form 5 in essence. The elements 9 are formed in such a manner that
their first flat side 14 corresponds to the first side of the tile, their
second flat side 15 corresponding to the second side thereof. In the form
5 the elements 9 are arranged vertically, i.e., concrete is cast from the
upper side. Two elements 9 are needed to produce one tile and n ~ 1 of
said elements are needed to produce n tiles.
Further, referring to Figs. 1 to 7, is described an apparatus for
carrying out the process of manufacturing concrete products, preferably
tiles, An apparatus according to the invention comprises a storage bin 1
arranged on a screw pump 2. The latter is through a gearbox 2' driven by
means of a drive 2", A pipe line 3 fixed on a stand 3' is connected to the
discharge end of the pump 2. The other end of the pipe line 3 is connected
to an essentially trapezoidal charging head 4 to which a row of discharging
nozzles 6 is interconnected. Said nozzles are removably fixed to a bottom
7 of the head 4 which is in the area of penetration of each nozzle 6
therethrough proYided with a wear resisting plate 8. Sides of the plate 8
facing away from the bottom 7 lie in a plane parallel thereto. A blocking
unit 8' is slidingly and movably arranged on the plates 8 of each row of
the nozzles 6. Said unit comprises closures 9 being mutually rigidly
connected by means of a linkage 10 which is interconnected with the air- or
hydraulic-working cylinder 11. The latter enables simultaneous moving of
all closures 9 over the plates 8 and closing and opening the nozzles 6
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respectively.
In the area above each closure 9, there are throttle knives 12
arranged slidingly and movably in the same plane as said closure and
extending over the entire length of each row of nozzles 6. The throttle
knives 12 are, with respect to the closure 9, staggered in their plane in
the direction away from the working cylinder 11, the closures 9 being
provided with a lug 9' cooperating with the knives 12, The side of the
knives 12 facing away from the working cylinder 11 is shaped as a half-wave
of a sinusoldal curve 13, the curvature of which is determined by the
mutual distance between the two utmost nozzles 6, by material cast and by
the pressure for pressing material into the noz71es 6. On their side
facing away from the bottom 7, the throttle knives 12 are reinforced by
means of a brace fillet 14 and mutually connected by means of a linkage 15.
On the linkage 10 there is provided a back stop 16 meshing with the linkage
15. The latter penetrates the wall 4' of the head 4 on the side facing
avay from the working cylinder 11 whereby the linkage 15 is between the
said wall and a limit stop 17 provided with a tension-compression spring 18
which enables moving of the throttle knives 12. To a part of the linkage
15 projecting through the wall 4', a nut 18' is screwed thereon, the stroke
of the throttle knives 12 being regulated therewith.
The operation of the blocking unit is further described with reference
to Figs. 6 and 7. In the starting position, the nozzles 6 are closed by
means o~ closures 9. The lugs 9' arranged on said closures hold the
throttle ~nives 12 in a closed position. Moving the closures 9 by means of
the linkage 10 and the working cylinder 11 in the direction towards the
cylinder 11 results in an opening of the nozzles 6. The spring 18, which
is compressed in the starting position, repulses the throttle knives 12 by
means of the limit stop 17 and the linkages 15 in the same direction as the
closures 9 are moving. The spring 18 acts on the throttle knives 12 until
the nut 13' rests against the wall 4' of the head 4. Thus, the closures 9
continue to move so that they completely open the entrance into the nozzles
6. Between that side of each throttle knife 12 lying in front of the curve
13, and the lug 9' of each closure 9, there is a distance a at nozzles 6
completely open, in dependence upon the material cast. Thus, entries into
the nozzles 6 due to curve 13 on the knives 12, overlap in a different
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degree when the closures 9 are in the open position, The more the entrance
of each nozzle 6 lies away from the place of supply of the concrete mass
into the charging head 4, the smaller the de8ree of overlapping. In such a
manner, the same pressure is ensured at the entrance into each nozzle 6
and, therefore, at the outlet thereof, the smaller the degree of
overlapping, the lower the pressure drop. The degree of overlapping thus
reflects the fùnction of the mutual distance apart of the utmost two
nozzles 6, of the material cast, and of the pressUre for pressing material
into the nozzles 6.
The entrance into the nozzles 6 is closed by means of the working
cylinder 11 pushing the closures 9 through the linkage 10 and the lug 9' of
each closure 9 pushing the throttle knives 12 into the starting position.
The spring 18 is therefore compressed and the blocking unit 8' is ready for
the next working cycle.
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