Apparatus for fabrication of concrete brick

Apparatus for making a concrete brick, the brick having at least one visible surface having a texture similar to that of natural stone. The brick may be made by filling a mold with concrete, vibrating the mold, and using a descending plunger to compress the concrete in the filled mold. At least one interior surface of the mold has a textured surface used to form the texture in the brick. Following compression of the concrete, a movable sidewall of the mold is moved laterally away from the brick a distance sufficient for the textured surface of the mold wall to clear the textured surface of the brick when the mold is raised. With the plunger remaining in place, the mold is raised, following which the plunger is raised.

BACKGROUND OF THE INVENTION 
Many different cast concrete moldings are known. Such pre-cast bricks are 
used to build free-standing or retaining walls. The present invention 
concerns a new pre-cast brick of this type and a process and apparatus for 
the industrial manufacture of the brick. The conventional manner of 
manufacturing such concrete elements is to cast them in varied shapes by 
means of a special apparatus. This is principally done using a box-shaped 
mold with the negative shape of the finished element on the inside. This 
mold is placed on a support board, the board being pushed onto a vibrating 
table by a special board carriage running on tracks. The table functions 
as a main vibrator and is located beneath the support board. The mold 
cavity is then filled with concrete. This is done by a mobile hopper which 
is loaded automatically from a storage tank containing ready-mixed 
concrete. Concrete passes from the storage tank into the mobile hopper 
through a spout. As soon as the mold is full of concrete, the mobile 
hopper is moved back into position beneath the storage tank spout, and a 
plunger descends upon the concrete in the mold. The cross-section of the 
plunger is identically matched to the top outside surface of the finished 
molding. Usually the plunger is hydraulically pressed down on the concrete 
in the mold. Simultaneously, it also works as a vibrator at the top of the 
mold, while a main vibrator located under the bottom of the mold. i.e., 
beneath the board carriage, works together with the vibrations from the 
plunger. Thus, vibration comes from both above and below at the same time 
as the plunger is being pushed down, resulting in substantial compression 
of the concrete in the mold. Every angle and corner of the mold is thus 
optimally filled with concrete. As a result of the compression, the 
concrete reaches a level of hardness that permits immediate de-molding of 
the finished element. To this end, the mold is raised vertically along the 
plunger and over it, while the plunger itself remains in position, 
pressing down the concrete. As soon as the lower edge of the mold has been 
raised above the plunger surface, the plunger is carried along by the mold 
and raised with it. The finished pre-cast brick now remains in its 
de-molded form on the support board and is pushed away by the board 
carriage for onward transportation by a conveyor system. The empty board 
carriage is then moved back into position. On its return journey, it 
pushes another support board onto the main vibrator. Now, the box mold is 
lowered back onto the support board and re-filled with concrete. In this 
conventional process, the pre-cast element is always vertically de-molded 
by raising the mold perpendicularly. It is the inside surfaces of the mold 
that determine what kind of external side and visible upper surfaces the 
finished element will have, with the exception of the top. Due to the 
vertical movement of the mold during de-molding, it is not possible to 
shape any surfaces of the finished casting other than those listed above. 
To build retaining walls at varying angles of incline, special retaining 
wall elements in the shape of an open trough, for example, may be used. 
The individual elements are built into the slope which is to be retained 
starting from the bottom and working up. The layers of these elements 
usually recede somewhat, which means that each succeeding level is 
slightly further back than the one beneath it by a distance determined by 
the steepness of the slope. The elements themselves have stops which 
effectively prevent one element from being pushed out in front of the one 
below it. At the same time, these stops determine the maximum angle of 
incline that can be retained with elements of that particular kind. It 
would be especially desirable for the purpose of building up retaining 
systems for slopes to have elements with an overhanging front, because 
this would make it possible to retain much steeper slopes. 
Conventional pre-cast elements have smooth sides due to the manner of the 
fabrication process, because the mold scrapes along these sides during 
de-molding. If these smooth sides remain visible in a retaining wall, 
their appearance is bare, artificial and unattractive. 
It is desirable, therefore, to make pre-cast elements with variously 
textured visible surfaces, which would give a general appearance of 
natural stone. Until now, it has not been possible to manufacture a 
pre-cast concrete brick with, for instance, an overhanging and textured 
visible front, due to the fact that the mold is removed vertically 
upwards. 
SUMMARY OF THE INVENTION 
In a process according to the current invention, a box-shaped mold is 
positioned on a support surface. The mold has at least one movable 
sidewall having a textured surface disposed interior of the mold. The mold 
is filled with concrete. Then, the concrete in the filled mold is pressed 
from above with a plunger and is vibrated in order to form a concrete 
brick. The sidewall is then moved away from the brick, and the mold is 
raised while the plunger retains the concrete brick on the support 
surface. Then the plunger is raised, releasing the brick. 
Apparatus according to the current invention comprises a box-shaped mold 
for receiving concrete, the box being adapted to rest on a support 
surface. The mold has a plurality of sidewalls, at least one of which is 
movable, and a textured interior surface. A plunger is provided and 
disposed so as to press the concrete in the mold from above. At least one 
vibrator is provided for vibrating the concrete in the mold. Means are 
provided for moving the mold vertically to and from the support surface 
while the plunger is stationary. 
The invention also includes a concrete brick made according to the 
inventive process, the brick being characterized by at least one visible 
surface having a texture similar to that of natural stone. 
A purpose of this invention is to create a casting of the said type and a 
process and the apparatus for the fabrication thereof which would make 
possible the manufacture of a pre-cast brick with a textured front or an 
overhanging front, or both. 
The pre-cast concrete brick according to the invention and the process 
according to the invention are explained with reference to the drawings. 
The drawings also illustrate the description of an example of an apparatus 
for the execution of the said process.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The main components of the apparatus according to the invention for 
executing the process according to the invention are portrayed in FIG. 1. 
Movable sidewall 4 of a box mold can be seen on a support board 13, which 
rests on a so-called board carriage and can thus be moved horizontally 
from side to side. In the figure, sidewall 4 can be moved sideways from 
left to right in the drawing and vice versa at a right angle to its wall 
surface. It is connected to two bolts 10, which are fitted into and guided 
by a bolt bearing plate 6 having bearing bushes 14 that slidingly receive 
the bolts 10. 
At the end of each bolt, there is a sliding cap 12, each of which touches a 
control element 9. The base shape of the control elements 9 on both sides 
is such that they form a curved guide track for the bolts 10. (See, for 
example, the curved guide tracks shown in the embodiment of FIG. 2.) A 
slide plate 8 links the two control elements 9 and can be slid at a right 
angle to the leaf plane. 
Pressure springs 11 are disposed around the bolts 10 between the bolt 
bearing plate 6 and the sliding caps 12. These pressure springs ensure 
that the bolts 10 with their sliding caps 12 are kept pressed firmly 
against the control elements 9. If the sliding plate 8 is now operated, 
the sides of the control elements 9, each of which forms a curved guide 
track for the bolts 10, slide past the sliding caps 12 of the said bolts. 
The bolts 10 move back and forth correspondingly inside their bushings 14 
and move the sidewall 4 of the box mold. 
A removable texture plate 5 is attached to the inward-facing side of this 
wall 4. The texture 18 of the said texture plate is an imitation of any 
kind of natural stone as desired. It is, therefore, irregular, in order to 
give a nearly-natural appearance to the concrete moldings. 
A wide variety of materials is suitable for making the said texture plate 
5. The most suitable are, for example, polyurethane, so-called nodular 
iron or a common type of cast aluminum, steel or grey iron. The material 
for the texture plate 18 must in all events be capable of withstanding 
substantially high pressures, the poured concrete must not adhere to it, 
and the structure 18 must not be gradually eroded when the mold is filled 
with concrete. The newly-finished molding 1 is shown (hatched) in cross 
section to the left of the texture plate 5. 
Inside the mold, there is a mold insert 2, which is also a negative mold 
for the internal surfaces visible from above when the molding 1 is 
finished. This insert 2 consists of steel plates having the appropriate 
shape, and a lid which prevents liquid concrete from entering the hollow 
part during mold-filling. The mechanical system described above for moving 
the wall 4 and the texture plate 5 are protected by a special cover plate 
7 so that concrete cannot get into this area. 
The plunger 3 operates upon the free area at the top of the mold. The said 
plunger 3 functions at the same time as a surcharge vibrator. The main 
vibrator works from beneath the support board. 
The process according to the invention using the apparatus as portrayed 
above will now be described. The position at the start is that the support 
board 13 is free of all the devices shown in the drawing. It is disposed 
on a so-called board carriage preferably moved on rails. This board 
carriage is first moved into position beneath the apparatus so that the 
support board 13 is pushed onto a main vibrator and is positioned directly 
underneath the mold. 
Now, the mold is lowered onto the support board. This is mostly done with 
the help of hydraulic piston-cylinder units or by purely mechanical means. 
The step of the lowering of the mold gives the situation as shown in FIG. 
1, except for the molding 1 and the plunger 3, which have to be excluded 
at this stage. All the other devices, the mold insert 2, the texture plate 
5 and the sidewall 4, the bolts 10, their bearing plate 6 and the pusher 8 
with the control elements 9, are firmly attached to the mold. 
In the situation as shown, in which the texture plate 5 is at the extreme 
left due to the position of the control elements 9, and the shape inside 
the mold is a reversal of the finished concrete molding, the mobile hopper 
moves across the lowered mold. The said mobile hopper, consisting 
basically of an open frame, moves across the covered parts of the mold as 
well as its cavities. A storage tank containing liquid ready-mixed 
concrete is located above the site of fabrication. The said storage tank 
has a movable segment at its lower end in the shape of a snout with an 
aperture, through which the concrete is poured. The snout is opened by the 
mobile hopper as it passes underneath the storage tank. Next occurs the 
movement of the mobile hopper to and fro across the mold, filling the said 
mold with concrete as it moves. 
The plunger 3, which can be moved perpendicularly to the mold, now descends 
upon the concrete in the mold. In this position, as shown in FIG. 1, 
substantial pressure is applied to the said plunger and it begins to 
vibrate at the same time. From below the support board 13, the main 
vibrator begins to shake, together with the plunger 13 working as a 
surcharge vibrator. The concrete 1 in the mold is thus given ideal 
compression and vibration to ensure that it reaches all the angles and 
corners of the mold and completely fills them. 
At this stage, the molding 1 is ready for de-molding. Until now, the mold 
was simply lifted off vertically. This is no longer possible, however, 
because of the textured side 18 of the concrete molding 1. Moreover, the 
textured side 18 of the concrete molding 1 in the example shown in FIG. 1 
has an outward overhang at the top. For this reason, the next step 
comprises retracting the movable sidewall 4, to which the texture plate 5 
is attached, at least as far to the right as the distance between the 
highest and lowest points of the textured structure as measured 
horizontally. This retraction is done in the example shown by means of 
moving the control elements 9. When this happens, the sliding caps 12 of 
the bolts 10 slip along the lateral surfaces of the said control elements 
9, so that the said surfaces function as a curved guide track. The control 
elements 9 are moved by the slide plate 8 by means of a hydraulic 
cylinder-piston unit. 
The pressure springs 11 press the bolts 10 as far to the right as the 
sliding caps 12 permit, so that the bolts pull back the sidewall 4 to the 
right with the texture plate 5 attached to it. The maximum height 
difference of the curved guide track on control element 9 must, therefore, 
correspond to the distance desired due to the texture of the plate 5. The 
retraction of the texture plate 5 releases the newly-pressed and 
compressed molding enough to enable the next step of the process to be 
carried out, which is the raising of the entire mold. The important thing 
here is that the bottom edges of the mold must be raised a little higher 
than the bottom edge of the plunger 3 so that the mold peels cleanly off 
the upper edges of the newly-finished molding 1. 
The final step is the raising of the plunger 3, finally freeing the 
finished molding. The support board 13 holding the molding is pushed away 
from the main vibrator by the board carriage until it reaches the conveyor 
leading to a stacking ladder, a board storage unit which is unloaded by a 
special vehicle. This carries the finished moldings to special curing 
chambers where they are stored for curing. As soon as the board carriage 
has fetched a new board from a board-store and pushed it onto the 
vibrator, the process begins over again. 
FIG. 2 shows a plan of the apparatus identical in principle to that shown 
in FIG. 1. In this case, however, it is a multiple mold 17, enabling 
several moldings 1 to be fabricated simultaneously in one cycle. The 
drawing shows only a section of this multiple mold, i.e., one of its four 
corner sections. It can be repeated in the same way to the left and 
upwards as desired, and extended as required. The left half of the diagram 
shows a two-way mechanical device for simultaneously moving two of the 
retractable sidewalls 4 facing each other. Each of these sidewalls 4 has a 
texture plate 5 attached to it. The control pieces 9 are arranged 
symmetrically along the axis of the sliding movement. There are several of 
these symmetrical control elements 9 in sequence, and one sliding cap 12 
of a bolt 10 touches the side of each one. When the slide plate 8 is moved 
all the bolts to the left and right of it are displaced sychronously. This 
is very important because otherwise, the movable sidewalls 4 of the 
multiple mold 17 would jam. On the other hand, this mechanism can easily 
absorb pressure from the sidewalls 4 with the utmost simplicity. This 
pressure is generated during the compression of the concrete and works 
indirectly on the texture plates. The control elements 9 can absorb the 
reaction forces, since the said forces work on both sides thereof in 
opposite directions. 
De-molding is also trouble-free, even though the entire mechanism is 
substantially jammed by the heavy pressure of the plunger 3. It is no 
problem for a hydraulic cylinder-piston unit to shift the slide plate 8 
and release the blockage. 
A mechanism working on one side only is shown on the right of FIG. 2. Here, 
the pressure forces are given off to the external walls of the multiple 
mold 17. To make the slide plates 19 easier to move, they are mounted on 
special sliding bearings 16 on the sidewall. The multiple mold permits 
simultaneous fabrication of a number of castings 1 with differing facing 
textures, so that, as in natural conditions, various surfaces can be 
produced. When prefabricated castings with various surface textures of a 
similar kind are built into a structure, the general appearance gives an 
impression of irregularity reminiscent of natural stone, and the castings 
are hardly recognizable as prefabricated units. 
The same apparatus as just described in FIG. 2 is shown in FIG. 3 in 
cross-section. The plunger 3, the support board 13 and the lids 7, which 
prevent concrete from being poured onto the mechanisms during casting into 
the mold, can be seen in addition to the components already described 
above. 
FIG. 4 shows a casting molded according to the process of the invention as 
an example of the type used for building an ordinary wall. This brick has 
a visible surface 20 with a texture hardly distinguishable from hewn 
natural stone. As the multiple mold can be used to manufacture a whole 
range of castings with similar but varied textures, a wall built of such 
castings does, indeed, have a strikingly natural appearance. In FIG. 5, a 
wall built of such castings is shown. It is made up of several bricks of 
different sizes. (The bricks may be identical in size, if desired.) A 
range of different-sized castings like this can be produced with one 
multiple mold in one working cycle. If the castings are laid in varying 
sequence as shown here, and even inverted or placed at an angle of 
90.degree., the already varied texture of the facings is made even more 
naturally irregular. A wall of this type can hardly be recognized as 
consisting of industrially pre-fabricated castings. However, this kind of 
structural element is much cheaper than hewn natural stone. Moreover, the 
remaining sides of the castings are nice and smooth for laying. 
The casting portrayed in FIG. 6 is used specially for retaining walls. It 
is a hollow cuboid in shape and overhangs at the front, which is textured. 
The front edge is raised slightly higher than the other sides to form a 
protuberance 21, which functions as a stop for the casting above it when 
they are stacked up. The cuboid has one opening in the base. However, at 
least one third of the base is closed at the front with a partial floor 
22. The purpose of this floor is made clear by FIG. 7(a). 
FIG. 7(a) shows a stacked structure of castings according to the invention 
for retaining a slope. The front facing of each casting is pushed forward 
above the one below until it reaches the stop. Stacking bricks of the 
proportions shown here in this way makes it possible to retain an 
acclivity with a slope of up to 80.degree.. The cavities of the castings, 
which are like plant troughs, are filled with humus. The soil settles 
under the bricks, which have a partial floor, in such a way that a free 
space remains at the upper front of the casting below, allowing plants to 
be set in the earth. FIG. 7(b) shows a front view of the said structure. 
Each row of bricks is set halfway across the one below, leaving spaces for 
planting. 
FIGS. 8(a) and 8(b) show a retaining wall constructed with the same bricks, 
but where the latter are laid close together with a half repeat in 
relation to the row below. The peculiarity of this wall is the fact that 
no horizontal joints are visible. Instead of horizontal joints, each row 
juts out a little in front of the one above it, causing the wall to recede 
by the thickness of what protuberance in each succeeding row. These little 
steps have an unusual appearance, especially when viewed from the front, 
and relieve the austerity of a conventional vertical wall pattern. 
FIG. 9 shows a wall similar to that shown in FIGS. 8(a) and 8(b), but seen 
from above, a bird's eye view. It illustrates clearly how the bricks 
recede from one row to the next and are laid in a half repeat. The wall 
can easily be filled with soil or concrete even after completion, although 
it has proved better in practice to fill it as work progresses. 
Of course, it should be understood that a wide range of changes and 
modifications can be made to the preferred embodiments described above. It 
is therefore intended that the foregoing detailed description be regarded 
as illustrative rather than limiting, and that it be understood that it is 
the following claims, including all equivalents, which are intended to 
define the scope of this invention.