Device for manufacturing concrete parts

A device for manufacturing concrete parts, particularly concrete pipes, and based on the principle of sinking mold whereby a molding bottom ring together with a jacket are continuously lowered relative to a stationary mold core while concrete mixture is poured from above and distributed into the emerging molding space by a radial pressing device mounted on the top end of the mold core. Simultaneously with the lowering of the mold jacket and the molding bottom ring a supply device for delivering the concrete material is also lowered such as to keep a constant distance from the open top end of the mold jacekt. The radial pressing device is designed to compact the incoming concrete material in radial direction without imparting any torque thereto. In this manner any stress in the finished part, particularly between the concrete and reinforcing wire mesh is effectively avoided.

BACKGROUND OF THE INVENTION 
The present invention relates to a device for manufacturing concrete parts, 
particularly tubular parts in a sinking mold of the type which includes an 
upright holding fixture, preferably in the form of a central vibrator, 
secured to a stationary support, a mold core releasably mounted on the 
holding fixture, a mold jacket, a molding bottom ring and means for 
supplying concrete material. 
In a known manufacturing device of this kind operating with sinking mold 
jacket or rising mold core it is possible to produce concrete pipes, and 
also steel concrete pipes provided with a reinforcing wire mesh. If the 
device is operated according to the method of a rising mold core, very 
deep underfloor pits are necessary. If instead it is operated according to 
the known method of a sinking mold jacket, then the concrete material is 
supplied from a stationary supply device situated above the mold and 
concrete material is dropped from above into an open molding space. Due to 
the fact that in the device using the sinking mold method the mold jacket 
is continuously lowered relative to the mold core, the distance between 
the top end of the mold jacket and the supply device keeps increasing and 
accordingly there is a growing risk that the falling concrete material 
splinters to all sides and thus pollutes the parts of the molding machine 
and impairs the operation. 
When the filling of the molding space is completed then the excessive 
concrete material must have been removed by hand because there has been no 
possibility to remove it and also to smoothen the upper end of the 
concrete part by the machine. In the processing of tubular parts by means 
of a radial pressing device the upper end of the concrete pipe has been 
shaped by a radial pressing and compacting action which has been found as 
inadequate. In summary, the following difficulties have been encountered: 
If it is desired to produce steel concrete pipes there occurs for example 
the problem that during the filling process the introduced concrete 
material is catched in the reinforcing wire mesh and immediately compacted 
whereby cavities can result within the concrete part and a uniform filling 
and compacting of the concrete material is not guaranteed. When the mold 
is completely filled up and an additional comptacting is caried out by 
vibrations then stresses in the reinforcing wire mesh can be caused 
because the concrete material pulls the wire mesh downwards. Such stresses 
may lead to the formation of cracks during the subsequent removal of the 
mold jacket. Moreover, it may happen that the wires at the low side of the 
reinforcing mesh do not contact the concrete material but form therewith a 
cavity. Another substantial disadvantage is in that due to circular 
vibrations of the central vibrator a turning of the reinforcing wire mesh 
may occur such that further strain develops between the reinforcement and 
the concrete material in the completed tubular concrete part. This strain 
may lead to crack formations during the subsequent mold shell removal and 
in addition, to bending of the concrete parts, for example pipes. When 
using hydraulic compression with simultaneous vibration of the upper 
molding ring, the introduced pressing forces can also strain the 
reinforcing wire mesh which upon the removal of the molding shell are 
released and again may cause great damage in the finished concrete part. 
SUMMARY OF THE INVENTION 
It is therefore a general object of the present invention to overcome the 
aforementioned disadvantages. 
More particularly, it is an object of the invention to provide an improved 
device for manufacturing concrete parts wherein the danger of the crack 
formation in the completed parts especially during and after the removal 
of the mold jacket are at least substantially eliminated. 
In keeping with these objects and others which will become apparent 
hereafter, one feature of this invention resides in the steps of placing 
the molding bottom ring in a first level above the mold core, depositing 
the mold jacket on the molding bottom ring, sinking the mold jacket 
together with the molding bottom ring to a second level at which the mold 
core enters the mold bottom ring, supplying the concrete material at a 
third level above the mold jacket and discharging the concrete material at 
a discharge point above the open top end of the mold jacket, continuing 
the sinking of the mold jacket together with the mold bottom ring while 
distributing the concrete material to the molding interspace emerging 
between the mold core and the mold jacket, and at the same time, lowering 
the level of supplying of the concrete material to keep a substantially 
constant distance between the discharge point and the open top end of the 
mold jacket. 
Since during the filling and compacting process the entire concrete 
material supply device follows the downward movement of the mold jacket, 
the supply device and thus the discharge point of the concrete material 
remain always at the same relative position closely above the open upper 
end of the mold jacket. In this manner the danger that during the charging 
some concrete material is splattered in the range outside the mold jacket 
and thus is missing in the molding interspace, is counteracted and the 
inadequate filling of the molding space and the resulting disadvantages 
are substantially eliminated. The risk of the inadequate filling and 
compacting of the concrete material in the mold is eliminated also in the 
case when concrete parts reinforced by a steel wire mesh are being 
manufactured. At the same time it is achieved that the charged concrete 
material in the area of filling is more uniformly distributed and 
compacted and therefore a more homogenous filling of the molding 
interspace is obtained. A further advantage is in the fact that any 
fouling of the molding machine and of the adjacent environment due to the 
splattered concrete material is substantially eliminated and as a result a 
disturbance free operation is guaranteed. By virtue of a short path of 
fall of the concrete material a correspondingly shorter pouring time 
results. This has the advantage of shorter processing times in machine 
operations and in simpler as well as more accurate control. 
In the device of this invention almost no forces in circumferential 
direction are applied on the charged in concrete material. By lowering a 
top molding ring and pressing the same against concrete material in the 
molding interspace, the desired length of the concrete part is determined 
in a reproducible manner, and precisely shaped ends, especially the top 
ends of the concrete parts are obtained whereby a homogenous texture is 
achievable because the shaping is carried out by the axial compression and 
not by the conventional radial compacting from the inside toward the 
outside. Another advantage results from the fact that by means of the top 
molding ring the completed concrete part remains under load even after the 
removal of the mold jacket and the top molding ring acts as a press pad so 
that a reliable, disturbance-free process for removing the mold jacket is 
made possible and the risk is precluded that the completed concrete part, 
such as for example a completed tube does not crack or is not damaged by 
the formation of cracks in the range of shaped ends, for example of the 
top ends. The method of this invention creates a among others the 
condition for designing manufacturing devices which are extraordinarily 
verstile and suitable for the production in an automatic process almost of 
all products needed for the construction at underground level. This 
applies mostly for the non-reinforced concrete parts such as for example 
concrete pipes and for steel concrete parts for example steel reinforced 
concrete pipes and the like. The invention enables the production in an 
assembled mold for example, of shafts, cones, pipes and the like concrete 
parts, also with embedded components such as for example climbing irons, 
inner lining and the like. 
The device of this invention is characterized by upright guiding means 
secured to the stationary support to guide the concrete supplying means in 
opposite, substantially vertical directions relative to the top end of the 
sinking mold jacket. The device is applicable for the manufacturing of 
practically all concrete products needed in the underground construction. 
For example the device of this invention can produce in an automatic 
process shaft rings, shaft legs, small pipes for example up to 1,000 mm of 
total height, pipes up to 2,500 mm of total height, street drain pipes, 
rectangular tubular elements and the like whereby reinforcing wire meshes 
to produce steel concrete pipes are readily applicable. The device enables 
a uniform filling of the molding space with concrete material thus 
providing a uniform texture of the final product whereby in the steel 
concrete parts any cavities between concrete and reinforcing wire mesh are 
avoided. As mentioned before, any tension or stresses between the 
reinforcing wire mesh and the concrete are also eliminated. In summary, 
the danger of crack formation during the mold jacket removal is prevented. 
The device of this invention includes also a radial pressing device by 
means of which the filled in concrete material is compacted in radial 
direction toward the mold jacket. For a mold having a jacket only without 
mold core a pressing device is known having a bottom cylindrical smoothing 
piston provided on its periphery with rollers rotatable about vertical 
axes and being arranged at equal angular distances one from another. The 
rollers function as pressing rollers. Originally the entire roller 
assembly was driven by a single shaft. However, this arrangement has the 
disadvantage that strong torque was exerted on the concrete material and 
particularly when manufacturing steel concrete parts, on the inserted 
reinforcing wire mesh. For this reason, the roller assembly or head was 
modified into a counterrotational roller head in which the rotary movement 
of the soothing piston was opposite to that of the remaining rotary parts. 
This measure had reduced to a certain degree the effect of the torque. 
Nevertheless a rotation of the inserted reinforcing wire mesh could be 
completely eliminated. Another disadvantage is also the high degree of 
wear of the pressing rollers, the need of frequent cleaning of the latter 
and susceptibility to interference due to the concrete which may have 
deposited between individual rollers. It is also difficult to seal the 
bearings of the rollers. Due to high wear and high friction the entire 
roller head necessitates a very large driving power input and therefore 
costly driving motors with high power consumption are needed. Consequently 
the prior art pressing device is heavy and costly to manufacture. Moreover 
the control for the parts of the roller head rotating in opposite 
directions is complicated. 
All these disadvantages are avoided by the provision of a pressing device 
arranged for movement in a radial plane transverse to the longitudinal 
axis of the mold and driven by a separate motor to exert pressure on 
concrete material in the molding interspace. The pressing head of this 
invention is preferably exchangeably mounted on the top end face of the 
mold core. Alternatively it can replace the prior art roller head on the 
soothing piston. It will be understood that in the following description 
the term "mold core" may also denote the soothing piston in a modified 
version of the mold or a similar supporting part. The pressing device 
includes a circumferential pressing ring which is brought into a 
continuous radial pressing movement; the ring itself, however, is not 
directly rotated but is coupled to an eccentric shaft by a bearing which 
introduces a relative rotary movement between the eccenter and the ring. 
Only a concrete distributing member on the top side of the pressing device 
is jointly rotated by the driving motor to uniformly convey the incoming 
concrete material radially outwardly and uniformly distribute the same in 
such a manner that the radial pressing head continuously compacts the 
concrete material. In this manner no torque is introduced into the 
concrete material under process. Consequently, any stresses and 
particularly any relative rotations of the inserted reinforcing wire mesh 
are prevented. Without exception the radial pressing movement does not 
impart any rotary motion to the concrete material. In addition, the device 
of this invention is subject to a very small wear leading to a reduced 
driving power consumption and to reduced operational costs. The pressing 
head requires only a single central bearing resulting also in a further 
cost reduction. The bearing is installed in the interior of the pressing 
head and protected against fauling or damage from the outside. It will be 
understood that the pressing head of this invention is either a part of 
the mold core or alternatively can be designed as a separate unit 
exchangeably attached to a conventional mold core. Since the radial 
pressing force exerted by the pressing head of this invention is 
sufficient for the complete compression of the concrete material then in 
principle any additional vibrators for the mold that means also the 
central vibrator in the mold core can be dispensed with. 
The central vibrator used in the preferred embodiment of this invention 
sets the mold core into vibrations at a relatively high frequency and with 
small amplitudes for example in the order of 1 to 4 mm. The pressing head 
in contrast oscillates at a relatively lower frequency, for example in the 
range between 100 to 800 oscillations per minute and at large amplitudes 
for example between 10 and 15 mm. By means of an elastic support, such as 
for example at least one rubber block provided between the mold core and 
the pressing head, the two different amplitude values are made possible 
and the mutual interaction between the two oscillating parts is kept low. 
With advantage, the direction of rotation of vibrations imparted to the 
mold core by the vibrator is opposite to the direction of rotation of the 
unbalanced arm of the pressing head whereby the possibility of imparting 
any torque to the concrete material is further reduced. Due to the low 
rotary speed of the drive for the unbalanced arm the same driving shaft 
can be employed also for the distributing device. In addition, the elastic 
support device between the pressing head and the mold core provides an 
excellent protective seal. In a modification of this invention, the 
housing of the pressing head is utilized as a distributing member, 
preferably by the provision of a stepped plate on the upper wall of the 
housing so that the wear on the distributing device is further reduced.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
FIGS. 1 through 3 show schematically a device 10 designed for the 
production of concrete parts 11 according to this invention. In the 
illustrated example the concrete parts are steel concrete pipes provided 
with a reinforcing wire mesh 12. It will be understood that the device is 
suitable for the production of other kinds of concrete parts for example 
pipes without reinforcing wire mesh such as residential or street drain 
pipes, shaft rings, shaft butts and the like. In this embodiment the 
device 10 is constructed as an underfloor machine supported in an embedded 
pit 13. The concrete parts 11 are produced in a mold consisting of a mold 
core 14 and a mold jacket 15 which surrounds the mold core with a radial 
spacing to delimit a molding interspace 16. In this example, the mold core 
14 is constructed as so-called vibrating core. It has the configuration of 
a cylindrical shell mounted on an upright central vibrator 17. The bottom 
side of the vibrator is secured to a base support 18 which is rigidly 
connected to the bottom of the pit 13. The upright vibrator 17 projects 
into the interior of the mold core 14 and extends up to the region of its 
upper end portion. In the top end region, the mold core 14 is releasably 
connected to the end of the vibrator 17 by means of a clamping device 19. 
The top end face of the mold core 14 is provided with a schematically 
indicated radial pressing device 20 which is an integral part of the mold 
core and its detailed construction will be explained later on. 
The device of this invention includes a stationary upright guide 21 which 
is for example integrally connected to the machine frame at the bottom of 
the pit 13. The upright guide 21 supports and guides for a sliding 
movement in the vertical direction a schematically indicated mold ejector 
22. The mold ejector has an L-shaped cross-section whose upright part 
forms a carriage 23 guided along the upright guide 21. The horizontal part 
of the mold ejector 22 carries a lower machine table 24 in the form of an 
exchangeable plate having a central opening 25 which slightly exceeds the 
outer diameter of the mold core 14 to pass the core therethrough. The 
lower machine table 24 serves as a seat for supporting the bottom mold 
ring or lower socket 26 which is a component part of the mold. The molding 
bottom ring 26 in this example rests on a vertical spacer 27 which engages 
the lower machine table 24. The molding bottom ring 26 serves for shaping 
the lower end portion of the concrete pipe 11 being produced. In this 
example, the lower end of the concrete part to be produced has a bell 
shaped configuration whereby the flared parts of the bell adjoining the 
lower end face of the concrete pipe is determined in conventional manner 
by the shape of the molding bottom ring 26. 
The vertical part of the mold ejector 22 is provided with vertical guide 
track 28 for slidably supporting a guiding carriage 29. The horizontal 
part of carriage 29 holds the top end of the mold jacket 15 such that the 
latter is moved in vertical direction along the guide track 28. 
The vertical guide track 28 of the mold ejector 22 projects relatively high 
above the upright guide 21 and is provided at its upper end with a 
horizontal arm 30 which supports a vertical translation drive 31, for 
example in the form of a cylinder and piston unit whose downwardly 
directed piston rod 32 is terminated with a disc 33. The disc 33 carries a 
molding top ring 34 which serves for shaping the upper end portion of the 
concrete part 11 being produced, for example the shaping of a spigot end 
of the pipe. By means of the translation drive 31 the molding top ring 34 
is moved in vertical direction to and from the molding interspace 16. In 
addition, the translation drive 31 imparts to the top ring 34 a 
reciprocating rotary motion about its center axis. 
The device 10 of this invention further includes at least one charging or 
supply device 35 for concrete material. As schematically illustrated the 
supply device 35 includes a storage container 36 for the concrete material 
and at least one conveying device 37, for example in the form of a 
horizontally directed conveyor band arranged below the storage container 
36. The transporting or conveying device 37 extends in horizontal 
direction from storage container 36 toward a discharge point 40' above the 
open top of the mold jacket 15 in the carriage 29 and is arranged on a 
retractable support 38 which is movable by a non-illustrated drive in two 
opposite horizontal directions indicated by a double arrow. The free end 
portion of the retractable support 38 is connected with a downwardly 
directed wiping device 39, for example in the form of a wiper ring 
surrounding the discharge point 40' of the layer of concrete material 40 
conveyed by the conveying device 37 and fed by a free fall into the mold 
jacket 15 (FIG. 2). The entire charging or supply device 35 is movable in 
vertical direction parallel to the center axis of the stationary mold core 
14. Preferably the entire charging or supply device 35 is guided along a 
vertical track. In the illustrated example, the supply device 35 is firmly 
connected to the vertical part of the mold ejector 22 and is guided along 
the upright guide 21 which forms a part of the machine frame. 
In another, non-illustrated embodiment there is provided a separate upright 
guide for the supply device 35 which is also an integral part of the 
machine frame and is provided with a separate vertically movable sliding 
carriage which supports the component parts of the supply device 35 and is 
driven by its own driving device for example by a pressure fluid actuated 
hydraulic drive. 
The method of operation and of the production of concrete parts in the 
device 10 is as follows: 
In a preliminary operational stage the carriage 29 with the suspended mold 
jacket 15 is lifted along the vertical guide track 28 from the position 
illustrated in FIG. 1 into its uppermost position close to the horizontal 
arm 30 in which the mold jacket 15 is completely withdrawn from the 
previously completed concrete part 11 and the part is removed. The 
carriage 29 with the mold jacket 15 then remains in the uppermost 
position. Thereafter a new molding bottom ring is provided with the 
reinforcing wire mesh 12 and deposited on the ejector plate of the lower 
machine table 24 either by hand or with advantage by means of an automatic 
device. In this example, it is assumed that only a single concrete part 11 
is produced in an operational cycle. In principle, it is possible to 
produce a plurality of concrete parts having the same or different size in 
the same production cycle. In this case a corresponding number of molding 
bottom rings 26 are deposited side-by-side on the ejector plate of the 
lower table 24. 
Then the drive of the carriage 29 is activated to move the mold jacket 15 
downwardly along the guide track 18 until the lower end of the mold jacket 
engages the rim of the molding bottom ring 26 in the position illustrated 
in FIG. 1. During the downward movement of the mold jacket 15 the mold 
ejector 22 remains in its initial position illustrated in FIG. 1. 
After the mold jacket has been seated on the molding bottom ring 26, the 
drive for the carriage 23 of the mold ejector 22 is actuated to move the 
carriage 23 and hence the mold ejector 22 downwards along the upright 
guide 21 until the top side of the mold core 14 together with radial 
pressing device 20 enter through the inner opening of the molding bottom 
ring 26 the lower part of the mold jacket 15. Then the supply device 35 
for concrete material is activated to move the support 38 together with 
the conveying device 37 from its retracted position illustrated in FIG. 3 
into its operative position illustrated in FIG. 1 in which the discharge 
point 40' of the conveying device is above the open top end of the mold 
jacket 15 and a layer 40 (FIG. 2) is transported by the conveying device 
37 from the storage container 36 and discharged from above into the 
molding interspace 16. Simultaneously, the central vibrator 17 and the 
radial pressing device 20 are activated. As a consequence, the concrete 
material present on the top end of the mold core 14 is continuously 
displaced in radial direction into the molding interspace 16 and is 
compacted therein by combined actions of the vibrator 17 and radial 
pressing device 20. As mentioned before, the device 10 operates according 
to the so-called sinking mold method. That means that as soon as at the 
beginning of the operating cycle when the molding interspace 16 is filled 
with concrete material first in the region of the molding bottom ring 26 
and the concrete is compacted into the lower bell-shaped interspace around 
the bottom ring 26, the entire mold ejector 22 together with the carriage 
29 and the mold jacket 15 mounted thereon and further together with the 
supply device 35 for the concrete material are moved downwardly in 
vertical direction along the upright guide 21, preferably at a constant 
speed while continuously feeding by conveying device 37 a layer of 
concrete material 40 into the mold. By a non-illustrated dosing device the 
amount of concrete material 40 supplied by the supply device 35 is 
controlled in dependency on suitable operational parameters, such as for 
example, the power consumption or the torque of the radial pressing device 
20. The torque can be determined for example from the input power required 
by driving aggregates or by pressure medium such as a pressure fluid in a 
hydraulic drive for the radial pressing device 20. According to the sensed 
power values the conveying device 37 is continuously controlled to convey 
a corresponding amount of concrete material 40. The charging proceeds in 
this manner while the mold ejector 22 together with the carriage 29, the 
mold jacket 15 and the supply device 35 keep sinking at a constant speed 
toward the bottom of the mold core 14. As soon as the top end of the mold 
core 14, namely the radial pressing device 20 mounted thereon, is 
approximately flush with the upper edge of the mold jacket 15 then the 
downward movement of the mold ejector 22 is stopped and the charging of 
the conveyor device 37 is interrupted. The support 38 together with the 
conveying device 37 is retracted to the left whereby the wiping device 39 
attached to the bottom side of the free end of the support 38, wipes off 
excessive concrete material 40 at the upper end of the mold. 
Subsequently, by means of the vertical translation drive 31 the molding top 
ring 34 is displaced from above into the top part of the molding 
interspace 16 until the top ring 34 reaches a predetermined level within 
the mold jacket 15. At this predetermined level the downward movement of 
the translation drive 31 is stopped and simultaneously a reciprocating or 
oscillatory rotary movement about the center axis of the mold is imparted 
to the top ring 34. Now the mold ejector 22 together with the carriage 29, 
the mold jacket 15 and the molding top ring 34 are slowly moved downwards 
whereby the top ring 34 is moved further into the molding interspace 16. 
During this downward movement of the top ring 34 the upper end of the 
concrete part 11 is shaped, for example to form the spigot end of the 
concrete tube. The length of the concrete tube is determined by the final 
position of the top ring 34 in the mold. The final position is constant in 
each working cycle because the top ring 34 does not exert any compacting 
pressure during its downward movement but merely provides a displacement 
of the concrete material. Only at the end of this process step the central 
vibrator 17 and the radial pressing device 20 are inactivated. To remove 
the mold jacket the carriage 29 together with the mold jacket 15 is moved 
upwards whereby the molding top ring 34 acts as a backing and remains in 
contact with the top end of the completed concrete part 11 to serve as a 
press pad. This arrangement enables a reliable shelling off process 
without the risk that the completed concrete part 11 such as a pipe, 
cracks or that the shaped end, for example the spigot end of the concrete 
part becomes damaged. Alternatively, it is also possible to move the mold 
ejector 22 upwards simultaneously with the mold jacket 15 whereby the top 
ring 24 again serves as a press pad. The device 10 enables a novel method 
of manufacturing concrete parts 11 such as pipes, shaft rings and the like 
which can be employed particularly when steel concrete pipes with embedded 
reinforcing wire mesh are to be manufactured, to operate according to the 
principle of the sinking mold. The method of this invention is 
characterized in that the mold ejector 22 and/or the reinforcing wire mesh 
12 are first put on the molding bottom ring 26 situated above the mold 
core 14. Then the bottom ring 26 together with the reinforcing wire mesh 
12 and the mold jacket 15 are moved down to such an extent until the upper 
end of mold core 14 and the radial pressing device 20 arranged on the top 
end enters the bottom ring 26 and the mold jacket 15. Thereafter a layer 
of concrete material 40 is fed into the molding interspace 16 from above 
while the vibrator 17 and the radial pressing device 20 are activated to 
distribute and compact the charged concrete material until the mold jacket 
and the bottom ring 26 are lowered to their final position at the bottom 
of the mold core 14. The charging or supply device 35 is lowered 
substantially in synchronism with the sinking of the bottom ring 26 and 
mold jacket 15 such that the discharge point 40 of the concrete material 
remains always at the same distance from the open end of the mold jacket 
15. Due to this simultaneous downward movement of the supply device 35 and 
the mold jacket 15, the discharged layer of concrete material 40 thus 
falls into the mold substantially within the height range of the latter. 
As mentioned before, the supply device 35 can be moved together with the 
mold ejector 22 which also carries the mold jacket 15 and the bottom ring 
26 or by a separate guided drive independently of the mold jacket. In both 
cases, the mold jacket 15 and the supply device 35 are lowered at the same 
constant speed. Then when the bottom ring 26 and the mold jacket 15 have 
reached the lower end position the conveying device 37 in the supply 
device 35 is retracted laterally away from the top end of the mold jacket 
15 whereby the wiper device 39 on the support for the conveying device 
wipes off excessive concrete material at the top end of the mold. After 
this wiping step has been completed, the top ring 34 is moved from above 
into the open end of the molding interspace 16 to reach a predetermined 
level therein. At this level, the top ring 34 can be rotated back and 
forth about its center axis. Thereafter the bottom ring 26 together with 
the mold jacket 15 and the top ring 34 are simultaneously, that means as a 
single unit further lowered whereby the top ring 34 shapes the top end of 
the concrete part 11, for example to form a spigot end without exerting 
any compacting pressure with its disadvantageous consequences. 
The device for the manufacturing of concrete parts according to this 
invention has the following advantages: The device 10 enables an automatic 
production almost of all concrete products needed for the construction 
below ground level, that means concrete parts of diversified types and 
sizes, such as shaft rings, shaft butts, small pipes up to 1,000 mm 
height, pipes up to 2,500 mm height, street draining pipes, rectangular 
pieces, steel concrete pipes and the like. Consequently, the device 10 is 
extremely versatile. It permits a substantially improved utilization by 
its user. Furthermore, it is also of advantage that in the manufacture of 
pipes especially of those provided with the reinforcing wire mesh 12, any 
stresses which hitherto resulted between the wire mesh and the concrete 
material are eliminated. In conventional devices of this kind there has 
been the problem that in the course of the filling process the concrete 
material was catched on the reinforcing wire mesh and the remaining part 
was immediately compacted so that cavities resulted within the concrete 
part, particularly within a steel concrete pipe, because a uniform filling 
and compacting could not be guaranteed. Furthermore, when the mold was 
filled up and a further compacting was followed by vibrations, there 
resulted stresses in the reinforcing wire mesh because the concrete tends 
to draw the wire mesh downwards. Such stresses during the subsequent 
removal of the mold jacket may lead to the formation of cracks in the 
completed concrete part 11. Moreover, it happens that the wires of the 
reinforcing mesh are surrounded by cavities at their lower sides. 
Furthermore, the known devices have the serious drawback that due to 
circular motions or rotary vibrations of the vibrator an angular 
displacement or turning of the reinforcing wire mesh occurred so that 
between the wire mesh and the charged concrete material additional 
stresses developed. In the subsequent removal of the mold jacket the 
additional stresses again may cause cracks and/or an arching of the 
finished concrete part, for example a pipe. In addition, compacting 
pressures introduced in conventional devices by molding upper or top ring 
in combination with the superposed vibrations have produced additional 
stresses in the reinforcing wire mesh which again after the removal of the 
shell lead to the crack formation. 
The device 10 of this invention makes it possible to completely eliminate 
any stresses between the reinforcing wire mesh 12 and the remainder of the 
finished concrete part 11, thus avoiding the formation of cracks during 
the withdrawal of the mold. Any angular displacements of the reinforcing 
wire mesh about the longitudinal axis of the mold are counteracted. Since 
the feeding of the concrete material from the supply device 35 takes place 
always from a constant height with respect to the mold jacket 15, namely 
closely to its top end, any splattering or spraying of the concrete 
material during its filling is avoided. The charging of the mold proceeds 
more uniformly and constantly and consequently any formation of cavities 
between the wire mesh and the concrete is also avoided. Moreover, it is 
also of advantage that by means of the wiping device 39 in the supply 
device 35 an automatic wiping off of the concrete material in excess at 
the top end of the mold and thereby a smoothing of the top end is made 
possible. Since the upper end of the concrete part 11 is shaped by the 
axial movement of the molding top ring 34 from above into the molding 
interspace, a substantially exacter and smoother shape of the end surfaces 
of the concrete part are achieveable than those produced only through the 
radial pressure exerted by the radial pressing device 20. Another 
advantage is that the device 10 in addition to the above-described mode of 
production of tubular concrete parts, is suitable also for other types of 
concrete parts such as for example of shaft rings. This versatility 
results from the vertical shiftability of the entire supply device 35 
which for example when manufacturing shaft rings is movable in vertical 
direction down to the ground level as required for the molding of shaft 
rings. Also the molding top ring 34 with its separate driving device also 
contributes to the improved production of shaft rings. In general the 
device 10 and its control of individual working cycles is simple. The 
device 10 is readily adaptable for the manufacture of a great assortment 
of diversified concrete parts 11 of different sizes. 
In the embodiment illustrated in FIGS. 4 and 5, the component parts 
corresponding to the embodiment of FIGS. 1 to 3 are referred to by the 
same reference numerals preceded by 1. 
In this embodiment the mold core 114 is again mounted on a stationary 
upright holding fixture 141 by means of a schematically indicated clamping 
device 119. In this example, the clamping device is a component part of 
the top outer surface of a central vibrator 117 and is designed such as to 
releasably clamp and center the inner wall of the mold core 114. 
The upper end face of the mold core 114 is provided with a radial pressing 
device 120. The device 120 includes a pressing head 143 supported for a 
rotary wobbling movement within the confines of the top end face 142 of 
the mold core 114 to exert a radial pressure on the incoming concrete 
material. The pressing head 143 is set into wobbling rotary motion by an 
eccentric 149 driven by a motor 144 centrally arranged within the mold 
core 114. The motor 144 is attached to the upper cover plate 146 of the 
mold core 114 and the eccenter shaft passes through a central opening of 
the cover plate. 
In another non-illustrated embodiment the pressing head 143 is driven by an 
external drive arranged such that the pressing head 143 is mounted as a 
separate supplementary element on a smoothing piston or on another mold 
core and is driven from above by a driving shaft. 
The vibrator 117 is driven preferably in counter direction to the direction 
of rotation of the driving motor 144. The driving motor 144 has a drive 
shaft 147 which is coaxial with the longitudinal center axis 145 of the 
mold core 114. The eccenter 148 for driving the pressing head 143 is 
formed on the coaxial drive shaft 147 and its center axis 151 is offset by 
a distance e relative to the center axis 145 of the mold core 114. The 
eccentric 149 supports by means of ball bearings 152, 153 a ring-shaped 
body 150 of the pressing head 143 for free rotation about the center axis 
151 of the eccentric. The free rotation of the ring-shaped body 150 is not 
necessary but is advantageous in that it introduces no torque in the 
concrete material during its compression. The bearings 152, 153 engage the 
inner wall of central bearing box 154 which is firmly connected to the top 
disc 155 of the ring shaped body 150. The top disc 155 thus represents a 
cover of the pressing head 143. In a modification, the top cover disc can 
be provided with radial spokes extending between the ring shaped body 150 
and the bearing box 154. The distance between the top disc 155 of the 
pressing device above the upper surface of the cover plate 146 of the mold 
core 114 is determined by the height of the bearing box 154. A ring-shaped 
body 150 together with the top disc 155 has the configuration of a 
reversed cup. The lower annular side of the ring shaped body 150 slidably 
engages the top surface of the cover plate 146 of the mold core 114 and is 
set into a wobbling rotary motion in the radial plane 142 of the upper 
surface by the driving motor 144. 
The radial pressing device 120 further includes a distributing device 156 
arranged above the top disc 155 of the pressing head 143. In this 
embodiment, the distributing device is formed by at least one distributing 
arm 157 which slidably engages the upper surface of the top disc 155. One 
end of the distributing arm 157 is firmly connected to the free end of the 
drive shaft 147 of the motor 144 to continuously rotate about the center 
axis 145 of the mold core 114. As indicated in dashed lines in FIG. 5, the 
distributing arm 157 can be offset relative to the rim of the top disc 155 
of the pressing head 143. 
In another non-illustrated embodiment, the eccentric 149 projects through 
the center opening of the top disc 155 and the distributing arm 157 is 
secured to the projecting end of the eccenter shaft. 
When the driving motor 154 is switched on, the eccenter shaft 159 imparts 
to the radial free wheeling pressing head 143 a continuous pressing 
movement in radial direction. Due to the bearings 152, 153 a relative 
rotation between the eccenter shaft and the pressing head 143 is made 
possible whereby the pressing head 143 need not rotate during its radial 
movement. If this condition is not desired, then a rigid connected between 
the eccentric 149 and the pressing head 143 is provided. In the 
illustrated embodiment the driving motor 144 directly rotates in one or 
the opposite direction the distributing arm 157 only which displaces the 
concrete material discharged from above in radial direction outwardly into 
the molding interspace where the concrete is continuously compressed by 
the radially oscillating ring shaped body 150. Due to the idling rotation 
of the pressing head 143, no torque is imparted to the concrete and 
consequently any angular displacement of the reinforcing wire mesh 12 
(FIG. 1) is reliably prevented. 
In the illustrated embodiment, the central vibrator 117 through which the 
mold core 114 is set into a vibratory movement whereby a further 
compression is imparted to the concrete material in the molding space. 
In still another non-illustrated embodiment, the central vibrator 117 is 
dispensed with. In this case, the mold core 114 is releasably clamped by 
the clamping device 119 to a holding fixture 141 and the compacting or 
compression of the concrete material is performed exclusively by the 
pressing head 143. Since in this case only a radial compressing movement 
takes place no torque is introduced into the concrete. As a consequence, 
the pressing head is subject only to a minute wear and requires a reduces 
driving power so that the driving motor 144 can be smaller and of lower 
power input. Accordingly, the operational and construction costs are 
reduced. The design of the pressing head 143 inclusive of the bearings is 
inexpensive. It is also of advantage that the pressing head 143 can be 
mounted on the top end face of the mold core 114 of if desired can be 
applied as a separate element on another part, for example on a radial 
press where it is driven from above by a driving shaft. 
In a second embodiment of the pressing head 243 the ring shaped body 250 is 
secured to the top disc 255 at a distance above the cover plate 246 of the 
mold core 214 so that the bottom side of the ring shaped body 250 does not 
contact the cover plate 246. In this manner the movement of the pressing 
head is facilitated and the wear is reduced. The space between the cover 
plate 246 and the top plate 255 is sealed off by a circumferential sealing 
socket 260 of a resilient material. The sealing socket has an 
approximately C-shaped cross-section whereby its lower side engages the 
top cover plate 246 and is firmly attached thereto by means of a fastening 
ring 263 whose groove 264 engages an annular bulge 265 in the sealing 
socket. In a similar fashion, the upper side 266 of the sealing socket 
sealingly engages an annular groove in the ring shaped body 250. The ring 
shaped body is releasably fastened top the top ring 255. The sealing 
socket 260 is made preferably of rubber, synthetic rubber, resilient 
plastic material and the like which have a high degree of wear resistance 
when contacted with the concrete. For example, a commercially available 
wear resistance sealing material has the trademark "VULKOLLAN". 
Similarly as in the example of FIG. 4, the pressing head 243 is driven by 
the driving motor 244 via an eccentric 249 whose center axis 251 is offset 
relative to the center axis 245 of the mold core. In this embodiment, the 
distributing arm 257 is firmly connected to a protruding part 267 of the 
drive shaft which is coaxial with the axis 251 of the eccentric and 
therefore is offset with respect to the longitudinal center axis 245. 
In this embodiment the provision of the elastic sealing socket 260 ensures 
a complete seal-off of rotary parts arranged in the inner space 262 of the 
pressing head 243 from the molding space. Since the ring shaped body 250 
does not sit directly on the top cover plate 246 its motion is facilitated 
and frictional losses and wear are reduced. Consequently, the power 
requirements of the driving motor are further reduced and so is the 
overall wear. 
The third embodiment of the pressing head 343 illustrated in FIG. 7 differs 
from that of FIG. 6 only by a different arrangement of the distributing 
device. Instead of the rotating distributing arm, there is provided a cone 
shaped lid 368 covering the top disc 355 of the pressing head 343. The 
center axis of the conical lid 368 coincides with the eccenter axis 351. 
In this manner, the sloping surfaces of the lid 368 act as distributing 
device 356 which provides a uniform distribution of the incoming concrete 
material into the molding space. This embodiment is particularly 
advantageous for the production of concrete parts having a small nominal 
width. 
In a fourth embodiment of the pressing head 443 in FIG. 8 the eccentric 448 
is formed by an eccentric unbalance arm 469 which is at one end firmly 
connected to the drive shaft 447 of driving motor 444. The unbalance arm 
thus forms a heavy duty eccentric. Pressing head 443 has a closed housing 
470 enclosing the rotating unbalance arm 469. The housing 470 is supported 
on the top cover plate 446 of the mold core by means of an elastic 
supporting device 471 which includes at least one silent block 472 whose 
construction is similar to conventional vibration dampers. For example the 
silent block includes an annular rubber layer 475 sandwiched between an 
upper ring 473 and a lower ring 474. The unbalance arm 469 is supported 
for rotation in an axial bearing 477 arranged in the lower base 476 of the 
housing around the driving shaft 447. Similarly as in the embodiment of 
FIG. 4, a distributing arm 457 is attached to the drive shaft 447 above 
the end face of the housing 470. Also in this embodiment the driving 
direction of the vibrator 417 is preferably opposite to the direction of 
rotation of the unbalance arm 469 to counteract the possibility of turning 
the reinforcing wire mesh. The unbalance arm 469 is driven by the driving 
motor 444 at a relatively low speed at which the distributing arm 457 is 
also rotated. After switching on the driving motor 444 and the vibrator 
417, the concrete material is distributed by the arm 457 from the top of 
the housing into the molding space. By the action of the vibrator the mold 
core 414 vibrates at a relative high frequency and at small amplitudes for 
examples between 1 to 4 mm. The pressing head 443 on the other hand, 
oscillates at a low frequency, for example in the order of 100 to 800 
oscillations per minutes and at higher amplitudes for example between 10 
to 15 mm. The two different amplitude ranges are made possible by the 
rubber block 472 between the mold core 414 and the pressing head 443 which 
keeps the mutual influencing of the two frequencies at minimum. Due to the 
low rotary speed of the drive of the unbalance arm 469 the distributing 
arm 457 can be directly connected to this drive to rotate at the same 
speed. The elastic support device 471 has the additional advantage in the 
provision of excellent seal between the pressing head 443 and the top side 
of the mold core 414. The driving motor 444 is fastened to the base plate 
476 of the housing. 
The sixth embodiment of the distributing device 556 illustrated in FIG. 9 
distinguishes from the embodiment of FIG. 8 in that the housing 570 
performs both distributing and compressing functions. The jacket 578 of 
the housing 570 is formed as a stepped cone having annular steps 580, 581 
and 582 whose widths decreases from top to the bottom. Due to the strong 
oscillatory movement of the pressing head 543 and thus of the steps 580 to 
582 on the housing 570, the concrete material is conveyed outwardly in the 
direction of the molding space. In the manner any wear which might occur 
in the distributing arm 457 in FIG. 8 is avoided. 
FIG. 10 illustrates a modification of the device 610 of this invention 
which in principle corresponds to the device 10 in FIGS. 1 to 3. The 
difference resides in the provision of a mold jacket 615 which is 
cylindrical also at its bottom end and is provided at its lower edge with 
locking means in the form of a flange or ring 683 welded to the mold 
jacket in proximity to its bottom edge. Another centering ring 684 is 
screwed on the outer rim of the molding bottom ring 626 and abuts against 
the lower side of the welded ring 683. In addition, between the mold core 
614 and the bottom ring 626 is arranged an adjustable sealing device 685 
which is firmly connected to the mold ejector 622. The sealing device 685 
consists of a retaining ring 686 of an approximately S-shaped 
cross-section whose lower side is secured to the ejector plate 624 of the 
mold ejector and whose upper half serves for receiving a flexible hollow 
body 687 for example in the form of a rubber hose. The outer sides of the 
rubber hose 687 engage the inner walls of the upper part of the retaining 
ring 686 whereas the free inner side engages the outer surface portion of 
the mold core 614. The interior 688 of the rubber hose 687 is connected 
via a feeding conduit 689 to a source of pressure medium. If it is desired 
to activate the sealing device 685 then pressure medium is introduced into 
the inner space 688 of the hose to inflate the same at a pressure which is 
adjustable at will. In this manner the seal between the molding space and 
the mold core is readily adjustable so that even after the hollow elastic 
body or rubber hose 687 has been subject to a wear a constant compressing 
force of the hose against the mold core can be achieved. Normally the 
sealing device 685 is activated only during the filling and compressing 
steps when the rubber hose 687 is sealingly pressed against the outer 
surface portion of the mold core 614. During the removal of the mold 
jacket the rubber hose 687 is pressure released and the friction between 
the sealing body 687 and the mold core 614 is minimized and the core can 
be easily withdrawn. With activated sealing device 685 any leakage of 
concrete mixture between the mold core and the bottom ring is effectively 
prevented. 
The sixth embodiment of the distributing device 756 shown in FIGS. 11 and 
12 is similar to that of FIGS. 4 and 5 with the exception that instead of 
a distributing arm there is provided a distributing disc 790 secured to 
the eccentric shaft or eccentric 749 whereby the center axis of the disc 
790 coincides with the center axis 751 of the eccentric. The distributing 
disc 790 rotates a minute distance above the top surface of the cover 
plate 755 of the ring shaped body 750 of the compression head so that the 
distributor disc substantially covers the top surface of the disc 755. In 
a non-illustrated modification the distributing disc 790 is larger in 
diameter than the top disc or alternatively the diameter of the 
distributing disc is smaller than that of the top disc 755. 
In the illustrated embodiment, there is a minute clearance between the 
bottom side of the distributing disc and the top side of the cover disc of 
the pressing head. The circumference of the distributing disc is provided 
with an outwardly directed flange 791 which slidably engages a 
corresponding annular groove 792 in the upper side of the pressing head 
743. In this manner, a labyrinth-like seal is created which prevents the 
entry of concrete mixture between the ring shaped body 750 and the 
distributing disc 790. The distributing disc 790 is secured to the 
eccenter shaft eccentric 749 by a center screw 793 and as mentioned before 
rotates concentrically with the free rotary movement of the ring shaped 
body of the pressing head. In this embodiment the distributing disc 790 is 
provided on its upper side with equidistant, radially directed strips 794 
integrally connected to the distributing disc. The radial strips extend up 
to the circumferential edge of the distributing disc 790. As indicated by 
dashed lines in FIG. 12, the outer ends of the distributing radial strips 
794 are provided with radially projecting rounded projections 795. 
Additional convex projections 796 are provided on the upper surface of the 
distributing disc between the radial strips. In another, non-illustrated 
modification the upper surface and/or the circumferential side of the 
distributing disc 790 is provided with differently shaped projections such 
as webs, strips, cams and the like or recesses such as grooves, pits and 
the like. 
This embodiment of the distributing device 756 has the advantage of an 
extremely low susceptibility to wear because any entry of concrete mixture 
between the ring shaped body 750 and the distributing device 756 is 
completely eliminated. During the charging, the concrete material falls on 
distributing disc 790 and is rotated thereon. Due to this rotary movement 
a centrifugal acceleration of the concrete is created which swings the 
concrete outwardly to the molding space. By radial strips 794 or 
projections 795 and 796 the acceleration of the concrete is still 
increased. If the mold is overcharged, for example too much concrete 
mixture is present on the distributing disc 790, the torque increases 
accordingly. In the preferred embodiment the torque is measured and 
employed for the regulation of the operation, for example of the feeding 
rate of the supply device 35 (FIG. 1). In this manner the distributing 
device 756 provides a sensor for the overload regulation. 
While the invention has been illustrated and described as embodied in 
specific examples of the manufacturing device, it is not intended to be 
limited to the details shown, since various modifications and structural 
changes may be made without departing in any way from the spirit of the 
present invention. 
Without further analysis, the foregoing will so fully reveal the gist of 
the present invention that others can, by applying current knowledge, 
readily adapt it for various applications without omitting features that, 
from the standpoint of prior art, fairly constitute essential 
characteristics of the generic or specific aspects of this invention.