DE4341387A1 - Vibrating table for vibrating a mass to be compacted and vibrating method for compacting concrete - Google Patents

Description

The invention relates to a vibrating table for vibrating a to be compacted Mass - especially concrete - its main level in operation essentially is arranged horizontally and the one containing the mass to be compressed Form carries, and at least one unbalanced, driven (Excitation) shaft for generating an excitation force is stored.

It is not under a vibrating table in the sense of the present invention to understand only one table in the classic sense, d. that is, one continuous Table-top device, but it should also all those Types of construction are understood here, which correspond to those to be compressed Use the concrete-containing mold as part of the vibrating table. So are For example, vibrating tables are known which only have one resting on supports Have frames to accommodate the shape or completely without a frame get along and require a correspondingly rigid form, which on two trestles or similar. The term vibrating table in the sense of the present In general, the invention is intended to encompass all devices intended for shaking an overlying shape are suitable.

The invention further relates to a method for compacting concrete.

In many areas of technology it is necessary to have containers Compact masses. This can be bulk goods, for example  act whose volumes are to be reduced; in particular this occurs Task on when concrete for the production of prefabricated components in Molds is shed. In order to achieve high strength values, it is available Setting the concrete is absolutely necessary, a high compaction too achieve. Various processes and Devices for compacting liquid concrete used, which all in the basic idea of the concrete to be compacted is essentially the same impress an oscillating or orbiting movement which leads to shear stresses in the concrete. This way, in the concrete contained air expelled and the concrete compacted accordingly.

The process of moving the liquid concrete over the mold walls Imprinting is referred to as shaking, vibrating or shaking. The for this Devices used are mainly used Frequency range and the vibration amplitude as vibration tables or Vibrating beams are sometimes referred to as vibration tables. In the spirit of this Invention, these terms are to be understood as used synonymously, d. that is, for the purposes of this invention, the only decisive factor is that one too Containers containing a compacting mass, in particular a container containing concrete Shape, undergoes a recurring movement.

The vibrating tables used in concrete plants either work with so-called Imbalance exciters, in which a rotating unbalance is an excitation force generates the table top and the shape stretched on it Vibrations excited, or with linear drives, such as Hydraulic cylinders or the like, which are periodically controlled by an appropriate control be operated. Known and commonly used unbalance exciters consist of a shaft mounted on the vibrating table, on the a weight is attached eccentrically. The shaft becomes electrical, pneumatic, driven hydraulically or via V-belts or similar.  

The linear drives have established themselves as the state of the art, in two directions lying perpendicular to each other in the table plane in the Table level, d. H. in the horizontal to shake. Because of this, there are two Hydraulic cylinder with control, two push crank drives or similar are necessary. The The shaking movement is carried out consecutively, i.e. that is, it will for example, first shaken in the direction of an X axis, then in Direction of the Y axis. The people working in the horizontal plane Excited vibrating tables are also called horizontal vibration tables designated. A treatise on the cheapest vibration parameters such vibration tables and the achievable compaction results himself in Bauzeitung 1973, 10th edition, p. 510 ff.

In order for concrete masses compacted using horizontal vibrating tables To achieve the necessary compression, it is necessary to use waves with high To generate energy density in the liquid concrete mass. For this, the most high-known vibrating tables known from the prior art Frequencies excited because the energy density is proportional to the square of the Frequency is. The frequency range commonly used extends from 25-300 Hz, i.e. that is, it is in the audible range. There is therefore one strong noise development, which is a problem for workers employed in concrete plants Represents health hazard. It is therefore a great effort been made to have the same compression effect in the To be able to realize a frequency range of less than 15 Hz, d. H. in one Frequency range that is hardly detected by the human ear. So are For example, devices have been constructed that range between 3 and Work at 10 Hz. To the required to compact concrete Achieving minimum acceleration are, however, to compensate for the lower frequencies require higher amplitudes, for example at a frequency of 5 Hz an amplitude of 5-6 mm. Because the ones to be made Precast concrete parts and thus the total mass of the liquid concrete containing form is very large, for example in the range of 10-20 t, is  Generation of appropriate parameters due to the high forces to be introduced difficult.

Vibrating tables are also known, in which those on the table surface superimposed, vertical form containing the concrete to be compacted Direction is vibrated. With only non-positive on the Table-mounted form can cause bumps if namely the acceleration of the mold is greater than 1 g. With form-fitting with the table connected form can avoid the bumps to To achieve a good compression effect, however, are high frequencies necessary with the already described significant noise pollution and health damage for the workers employed in the concrete plants accompanied.

From DE-PS 41 16 647 a vibrating device is known in which four horizontally arranged excitation shafts, each with one eccentrically arranged Weight, d. H. are unbalanced. Each of the four excitation waves points own drive, which is connected to a controller. One of four drives works as master drive, and the phase position of the unbalance of the three other drives are corrected with respect to the first drive, so that by superimposing the centrifugal forces of the four rotating Unbalanced masses a resulting excitation force in the vertical direction (Z axis) can be generated, the amplitude of which by adjusting the Relative phase position of at least two rotating unbalance masses can be influenced to each other.

This embodiment is of comparatively high structural complexity disadvantageous, which is only used to excite one-way to generate, therefore only a vibration pattern, which is too partial unsatisfactory compression results.  

While the vertically working vibrating tables the horizontally working Inferior to vibrating tables, especially with regard to noise development are, are the previously known horizontal vibration method with the The disadvantage is that the compression time is greater than that of vertical ones Process or vibrating tables.

The invention is therefore based on the object of a horizontal vibrating table to design, with a high compression effect within a shorter time is made possible with low noise pollution, and which is characterized by a simple construction. The invention is also the Task based on developing a horizontal vibrating table so that ever a variety of waveforms is possible to achieve a good compaction of the concrete or other masses to be compacted favor. The basic idea according to the invention provides a solution a generic horizontal vibrating table before that the at least one Excitation shaft is arranged vertically.

In a preferred embodiment of the invention, several can also Excitation waves, for example two or four, rotationally symmetrical to each other be stored on the vibrating table.

In general, this basic idea according to the invention, i. H. perpendicular to provide stored exciter shafts with unbalance, the problem that due to the rotating masses of the center of gravity Entire system occur, the moments around the Y axis or around the X axis generate, which in turn lead to the occurrence of vertical amplitudes. A disadvantage of this vertical generated by the moments mentioned Vibrations is in particular that these are torsional vibrations the X-axis or the Y-axis, whereby naturally the vertical Amplitudes in the outer area of the shape are larger than in or near the axis, which leads to the fact that the compression effect in the  Outside areas of the shape is relatively good, close to the center of gravity or axis however insufficient.

In addition to the uneven compaction effect, there is the occurrence of vertical vibration components the big problem that the Natural frequency of the entire system in the vertical direction so close to the Excitation frequencies can lie that the entire system, consisting of Vibrating table, attached shape with concrete to be compacted and the Total weight of the excitation waves resonates, with the occurring large amplitudes can then let the concrete spill out of the mold and damage the vibrating table.

The invention therefore lies in terms of its device-related part Sub-task based on the task of using a horizontal vibrating table According to the invention arranged vertically arranged excitation shaft so that suppresses the vibrations mentioned with vertical vibrations become.

From a vibration point of view, this subtask is comparable to that Task, the overall system, consisting of a horizontal vibrating table, overlying form containing the concrete to be compacted and the vertical form Shafts arranged on the vibrating table must be designed in such a way that in a vertical direction Direction at the frequencies in question, i. H. in the Frequency range below the hearing threshold, no resonances occur.

The solution to the second subtask is included in the generic vibrating table exciter shaft (s) arranged vertically according to the invention characterized in that the table is mounted so that it has two in the main level has perpendicular degrees of freedom (X, Y direction), in However, the direction of the earth's gravitational field is essentially rigid.  

With regard to a device-related part, the object of the invention based on a method for shaking (shaking, vibrating compaction) of in a form of concrete to be compacted so that the Compaction effect compared to the prior art improved or is at least maintained, but the noise is reduced and the process is based on a comparatively simple design Can carry out vibrating table.

With regard to the procedural part, the invention is thereby characterized in that the form containing the concrete to be compacted a vibrating table for circular vibrations in the horizontal Main table level is excited.

It has surprisingly been shown that sufficient to achieve Shear forces in the concrete for a sufficient compacting effect it by no means it is necessary to shake in mutually perpendicular directions, but that a uniform and circular movement to produce Shear stresses in the concrete to be compacted is sufficient, leading to the desired sufficient compaction of the concrete.

In an advantageous embodiment of a vibrating table according to the invention the vibrating table has exactly one excitation shaft, which is below the center of gravity the vibrating table is arranged. This embodiment is characterized by their simple structure and allows the implementation of the method according to the invention for vibrating or compacting concrete, namely the induction of a circular vibration of the form containing compacting concrete. Such a table is preferred or the only vertically arranged excitation wave at a frequency of 0- 10 Hz operated, d. H. in the area of poorly audible or not audible at all Frequencies.  

In order for the practical implementation of the storage provided according to the invention the vibrating table, d. H. with two perpendicular to each other Degrees of freedom (X, Y axis) in the main plane, but one in the essentially rigid bearing in the direction of the earth's gravitational field (Z axis) provided according to the invention, at least three, but preferably four or to use more monovalent bearings, which are preferably rotationally symmetrical are arranged to each other.

A monovalent bearing means a bearing that only can absorb forces in the direction of an action line in other planes but can not absorb bearing forces. Such monovalent bearings are preferably carried out in the form of tension elements, which in a particular simple embodiment are ropes. These ropes can, for example at least three points, but preferably four points on the vibrating table be arranged and for example on the hall ceiling of the respective Factory room. This arrangement or embodiment of the monovalent bearings are, however, disadvantageous in that the one above the Available space is used for the vibrating table and thus the free space Passage from other manufacturing facilities, material feed paths etc. is hindered.

In a particularly preferred embodiment, it is therefore preferred provided that the vibrating table above one in a factory floor recessed pit is arranged and that the bearings and the at least one vertical excitation shaft arranged below the table level in the pit are. In this way, one is compared to the last described Embodiment compact and space-saving arrangement of vibrating table and Storage and drive implemented.

It can further be provided that the unbalance weight consists of two Imbalance weights are composed, which are circular sector-shaped in cross section  are executed and one of which is rotatable on the excitation shaft is arranged and arranged by one on the other unbalance weight Driving pin is taken. The driver pin runs in one Groove so that different depending on the direction of rotation of the excitation shaft Cover angle of the two circular sector-shaped in cross section Unbalance weights result. If there is more overlap, the unbalance is correspondingly larger, so that at a certain speed of the excitation shaft a greater centrifugal force and thus excitation force is generated. In this way can create two different excitation torques at the same speed realize what is advantageous if, for example, molded concrete parts in several Layers are poured. When vibrating or vibrating the first one applied layer is then with a lower moment, i.e. H. with a less excitation force than when applying the second layer of concrete, which increases the total mass of the system accordingly.

In such an arrangement with one above a pit The vibrating table is preferably in the four corner areas of the vibrating table provided camp executed such that from the bottom of the Vibrating table extending downward substantially L-shaped trained brackets are arranged that from the bottom of the pit extending essentially L-shaped carrier so above are arranged so that their shorter (transverse) legs each have a shorter (Cross) leg of the bottom of the vibrating table down extending L-shaped brackets are arranged overlapping, and that the monovalent bearings in the form of elements that absorb tensile forces are formed, each between two overlapping (Cross) legs are stretched vertically.

With this embodiment according to the invention, it is compared simple construction measures created a vibrating table with which Compact heavy concrete masses effectively at low frequencies  leave without causing noise and without Center of gravity shift of the vertically arranged excitation waves vertical vibrations or torsional vibrations around the X and Y Generate axis that leads to resonances and thus a disturbance of the whole Systems can lead.

It is preferably provided in particular that the tensile forces absorb Elements are tension rods. Opposite also possible ropes as Tension elements have the advantage that they are also opposite Pressure load have a certain inherent stiffness, whereby the Resonance frequency of the entire system continues in the vertical direction is moved up, d. H. from the preferred operating range below the Hearing threshold outside the preferred range of the excitation frequency.

The proposed storage also has the advantage that it compared to the abrasive stone dust that is always present in concrete plants is insensitive.

On the other hand, the device according to the invention can also be used with others monovalent bearings can be realized, such as plain bearings or Bearings.

An alternatively provided storage according to the invention provides that each a bearing from one below the bottom of the vibrating table vertically in the pit arranged support is one at its upper and lower ends Disc made of elastomer material absorbing shear stress has that is designed so pressure-resistant in the vertical direction that the Complete system, consisting of a vibrating table and exciter shafts, one Natural frequency in the vertical direction of 25 Hz. Do it the elastomer discs in the direction of the X-Y plane through their Slidability and because of the long lever arm, the supports such as joints,  so that the desired shaking movement of the table in the horizontal plane is not hindered.

In addition, it can advantageously be provided that a total of two or four vertically arranged unbalanced shafts are rotationally symmetrical to each other are arranged. Such an arrangement offers the advantage that on the one hand the Circular shaking movement preferred according to the invention easily generated can be corrected by all two or four imbalances with the same Phase position are operated, but on the other hand by phase angle between linear vibration patterns are generated in the two or four imbalances can.

So when four unbalanced shafts are operated, they are rotationally symmetrical to each other in the four quadrants that are divided by the X and Y axes Main table level are arranged, an operation possible such that a and consequent movement of the vibrating table in the X direction or in the Y direction is produced. In addition, it is an arrangement of four excitation waves also conceivable, two excitation waves each, diagonally opposite, shut down and the two rotating excitation shafts with to operate a differential phase position of the unbalances, so that Vibration directions can be achieved that are at an acute angle to the X- or Y axis.

The excitation shafts are preferably driven by three-phase asynchronous motors driven, one of the motors being operated as a master drive and the other motors can be regulated as slave drives so that the desired Difference phase position of the unbalance on the rotating unbalance of the Master drive is defined.

The invention is described below with reference to one in the drawing Embodiment explained in more detail. The drawing shows:  

Figure 1 is a schematic representation of a vertical section through a vibrating table according to the invention, arranged in a pit of a factory floor, with an excitation shaft arranged perpendicularly below the center of gravity of the table main plane;

Fig. 2 is a plan view of a schematic representation of an alternative embodiment of the vibrating table shown in Fig. 1 with four rotationally symmetrical to each other arranged excitation shafts in a schematic illustration, wherein the phase position of the unbalance is equal to all four shafts,

Fig. 3 phase position and the direction of rotation of the four excitation shafts for translational excitation in the X-axis,

Fig. 4 phase position and the running direction of the four excitation shafts for translational excitation in the direction of the Y-axis,

Figure 5 is a schematic representation of phase angle and direction of rotation of two diagonally opposed shafts for translational excitation at an angle of 45 ° to the X- and Y-axis in a schematic representation. and

Fig. 6 shows an alternative embodiment of a bearing for a vibrating table according to the invention.

Fig. 1 shows a schematic representation of a vertical section through a vibrating table 10 according to the invention with a table top 12 which is mounted on four bearings 14 . The bearings 14 stand on the floor 16 of a pit 20 embedded in a factory floor 18 or are screwed there or fastened in another form.

On the table top 12 there is a shape 22 , indicated schematically by broken lines, which can be fixed by form-fitting holding means 24 . The form 22 contains concrete to be compacted, which is to bind to a prefabricated concrete component.

Each of the four bearings 14 initially has an L-shaped bracket 28 , which extends vertically downward from the underside 26 of the table top 12 and whose longer leg extends vertically downward. The shorter leg 30 runs horizontally to the horizontal, ie parallel to the bottom surface 16 of the pit 20 of the factory floor 18 . A likewise L-shaped support 32 extends vertically upwards from the pit floor 16 , the shorter leg 34 of which is arranged such that the respectively shorter (transverse) legs 30 of the holder 28 which extends vertically downward from the underside 26 of the vibrating table and the shorter (transverse) leg 34 of the support 32, which extends upwards from the pit floor 16 , is arranged to overlap one another. Between the two (transverse) legs 30 and 34 , a tensile force absorbing element 36 is stretched, which can be, for example, a wire rope, or preferably a tie rod. The pull rod can have threaded areas at its upper and lower ends, with which it can be screwed by means of attached nuts 38 .

In Fig. 1, a Cartesian coordinate system is further located, with the X-axis extends in the direction of the plane of the drawing to the right, while the Y-axis is perpendicular to the drawing plane. The positive coordinate direction on the Z axis faces the earth's gravity field. It is immediately obvious that, when the vibrating table is at rest, each pulling element 36 has to absorb a quarter of the total weight, as long as the additional weight of the unbalance of the excitation shaft is not taken into account.

Vertically below the center of gravity, ie arranged in the Z axis, there is an excitation shaft 40 which carries an unbalanced mass 42 which is arranged offset by an eccentricity e above the Z axis. The excitation shaft 40 is mounted in bearings 44 which are supported by a bearing tube 46 and are connected to the table top 12 . The excitation shaft 40 is driven by a drive, not shown in FIG. 1, which can be, for example, an electric motor directly connected to the shaft, a belt drive or the like.

When the exciter shaft rotates, the unbalanced mass 42 accelerated on a circular path generates a centrifugal force mrω 2, which generates the desired shaking movement in the XY plane. In addition, the unbalance creates an undesirable moment, which also rotates. In the position shown in FIG. 1, the unbalance 42 generates a static moment of size mge around the Y axis, which would lead to tilting of the table top 12 around the Y axis, ie in the direction indicated by arrows, in a conventional vibrating table . Due to the fact that it is a rotating moment, the moment acting around the Y-axis fluctuates periodically, so that there is a risk of resonance. Due to the bearing 14 according to the invention, the table top 12 of the vibrating table is mounted so stiffly with respect to movements about the Y axis and about the X axis that the resonance frequencies are so high that the entire vibrating table is in the Z axis, ie in the direction of the earth's gravitational field , can be regarded as essentially rigid at the rotational frequencies of the unbalanced shaft 40 in question. At the same time, the bearing 14 according to the invention of the vibrating table according to the invention ensures that a vibrating or oscillating movement in the XY plane is possible without any problems.

The vibrating table according to the invention thus enables a circular for the first time Vibration movement for the compaction of concrete for precast concrete elements, the has been found to be particularly advantageous since they are both excellent  Compaction results, as well as low noise pollution enables.

Although according to the invention the circular shaking movement has been found to be the most expedient for concrete, it may under certain circumstances be desirable to also generate translatory movements. From this viewpoint, a second embodiment of a vibrating table according to the invention is shown in Fig. 2 schematically shows 40 a- 40 d are arranged rotationally symmetrical to each other in which four excitation shafts. Fig. 2, the table top 12 is a schematic of the vibrating table, and four tension elements 36 of the bearing 14 not illustrated in detail. FIG. 2 further shows schematically the operation of the four excitation shafts 40 a- 40 d to generate the same circular shaking movement as is made possible by means of a single, larger imbalance in the embodiment shown in FIG. 1. In this operating mode, the four unbalances 42 a- 42 d of the four excitation shafts 40 a- 40 d rotate with the same phase position and direction of rotation. The load case shown in FIG. 2 with regard to the tension elements 36 is therefore essentially the same as in FIG. 1, ie the center of gravity of the overall system is shifted in the positive direction of the X axis, a positive moment being generated about the Y axis which is essentially absorbed by a higher load on the tension elements 36 lying on the right in FIG. 2. There are no torsional vibrations about the Y axis, since bearings of the embodiment as shown in FIG. 1 with reference to the bearing 14 are used according to the invention.

According to the invention, it is provided that the four excitation shafts are driven by four individual three-phase asynchronous motors; it is further provided according to the invention that one of the three-phase asynchronous motors, in the present case, for example, that assigned to the excitation shaft 40 a, functions as a master drive, ie that the rotating unbalance 42 a as rotating coordinate system is seen, on which the phase difference angles of the other excitation waves are defined and regulated.

As indicated in Fig. 2 by the dashed line 43 , in the event that only a circular movement is to be generated, a mechanical synchronization of the four excitation shafts in the form of a rotating toothed belt 43 or the like can take the place of the synchronization by means of electrical control means to step.

Fig. 3 shows an alternative operation of the four excitation waves, in which the lower two excitation waves 40 c and 40 d continue to operate in the mathematically positive sense of rotation, while the excitation waves 40 a and 40 b rotate in opposite directions. Two shafts rotate in one direction of rotation without a phase difference angle, while a difference angle of π is set between the two shaft pairs. In this way there is a translational excitation in the direction of the X axis. If one imagines the unbalance rotated from the position shown in FIG. 3 by an angle of rotation of π / 2, a static moment about the Y axis is generated which corresponds to that shown in FIG. 2. This is in turn supported by the bearing so that there are no undesirable vertical vibrations due to torsional vibrations around the Y axis.

Fig. 4, the operation of the four excitation shafts for translational excitation correspondingly shows the vibrating table according to the invention in the Y-axis.

As shown in FIG. 5, the arrangement according to the invention of four vertical excitation waves also opens up the possibility of stopping two diagonally opposite waves, for example, as indicated schematically in FIG. 5, the excitation waves 40 a and 40 d. If the two remaining excitation waves 40 b and 40 c are then rotated in opposite directions with a phase difference angle of π, there is a translational excitation, the line of action of which runs at an acute angle to the Y and X axes.

Fig. 6 shows an alternative embodiment of a bearing for a vibration table according to the invention. The table top 12 of the vibrating table rests on tubular supports 48 which stand on the hall or pit floor 16 . An elastomer washer 50 is arranged between the table top 12 and the tube support 48 and between the tube support 48 and the pit floor 16 . In the event of a vibration in the XY plane, the elastomer disks 50 are subjected to shear stress and thus enable a circular or translatory shaking movement in the XY plane. In the direction of the Z axis, the elastomer disks are compressed by the weight of the vibrating table 12 and the shape lying thereon with the concrete to be compacted. With a suitable selection of the hardness, the diameter and a small height of the disks 50 , the vertical natural frequency can be dimensioned such that it is far above the drive frequency of the unbalance 40 or the 4 excitation shafts 40 a- 40 d. In a preferred embodiment, the elastomer washers consist of an elastomer with a hardness of 90 ° Shore and have a diameter of 62 mm and a height of 10 mm. A vertical deflection of less than 1 mm results with a load of 700 kg per bearing point, the natural frequency in the direction of the Z axis, ie in the vertical, being 33 Hz. This value is significantly larger than the target operating range of the drive frequency of 0-10 Hz.

These supports or this form of storage for the invention Vibrating table for circular vibrating of concrete to be compacted has the Advantage on that it is inexpensive and easy to assemble. The disadvantage is that Safety stops must be attached to the side.  

The vibrating table according to the invention allows circular vibrations compacting concrete without this jarring movement by vertical Vibration components are disturbed.

Reference list

10 vibrating table
12 table top
14 bearings
16 pit floor
18 hall floor
20 pit
22 form
24 holding means
26 bottom (of 12 )
28 (first) L-shaped bracket
30 short (transverse) legs (of 28 )
32 (second) L-shaped bracket
34 short (transverse) legs (of 32 )
36 tension element
38 mother
40 excitation shaft
40 a- 40 d four excitation waves
42 unbalance
42 a- 42 d imbalances (from 40 a- 40 d)
43 timing belts
44 bearings
46 bracket
48 tubular support
50 elastomer washers

Claims (21)

1. vibrating table ( 10 ) for vibrating a mass to be compacted - in particular concrete - the main plane ( 12 ) of which is arranged substantially horizontally during operation and which carries a mold ( 22 ) containing the mass to be compacted and on which at least one imbalance ( 42 , 42 a-d) supporting, driven (excitation) shaft ( 40 , 40 a-d) for generating an excitation force,
characterized,
that the excitation shaft ( 40 , 40 a-d) is arranged vertically and
that the table ( 10 ) is mounted so that it has two perpendicular degrees of freedom in the main plane ( 12 ) (X, Y axis), but is mounted essentially rigidly in the direction of the earth's gravity field (Z axis). 2. Vibrating table according to claim 1, characterized in that the vibrating table ( 10 ) has exactly one excitation shaft ( 40 ) which is arranged under the center of gravity of the vibrating table ( 10 ). 3. Vibrating table according to one of the preceding claims, characterized in that the vibrating table is mounted on at least three monovalent bearings ( 14 ). 4. vibrating table according to claim 3, characterized in that the vibrating table ( 10 ) is mounted on four monovalent bearings ( 14 ) which are arranged substantially rotationally symmetrical to each other. 5. Vibrating table according to one of claims 3 or 4, characterized in that the monovalent bearings are designed in the form of tension elements ( 36 ). 6. Vibrating table according to claim 5, characterized in that the tension elements ( 36 ) are ropes. 7. vibrating table according to one of claims 1-5, characterized in that the vibrating table ( 10 ) above a in a factory floor ( 18 ) recessed pit ( 20 ) is arranged and that the bearings ( 14 ) and the at least one vertical excitation shaft ( 40 , 40 a-d) are arranged below the table level ( 12 ) in the pit ( 20 ). 8. vibrating table according to one or more of the preceding claims, characterized in that from the underside ( 26 ) of the vibrating table ( 10 ) extending downward substantially L-shaped brackets ( 28 ) are arranged that from the pit floor ( 16 ) from upward extending essentially L-shaped supports ( 32 ) are arranged such that their shorter (transverse) legs ( 34 ) each have a shorter (transverse) leg ( 30 ) from the underside of the vibrating table ( 26 ) downwardly extending L-shaped brackets ( 28 ) are arranged to overlap, and that the monovalent bearings are designed in the form of elements ( 36 ) which absorb tensile forces and are each stretched vertically between two overlapping (transverse) legs ( 30 , 34 ) are. 9. Vibrating table according to claim 8, characterized in that the tensile force absorbing elements ( 36 ) are tension rods. 10. Vibrating table according to claims 4, 6 and 8, characterized in that the tensile force absorbing elements ( 36 ) are ropes. 11. Vibrating table according to one of claims 2-4, characterized in that the monovalent bearings ( 14 ) are plain bearings. 12. Vibrating table according to one of claims 2-4, characterized in that the monovalent bearings ( 14 ) are roller bearings. 13. Vibrating table according to one or more of claims 2-4 and 7, characterized in that in each case one bearing ( 14 ) consists of a support ( 48 ) arranged vertically below the underside of the vibrating table ( 26 ), which at its upper and lower ends each has a disc ( 50 ) consisting of shear stress absorbing elastomer material, which is designed so pressure-resistant in the vertical direction that the overall system, consisting of vibrating table ( 10 ) and excitation shafts ( 40 , 40 ad), has a natural frequency in the vertical direction of 25 Hz. 14. Vibrating table according to one of the preceding claims, characterized in that a total of four vertical excitation shafts ( 40 a-d) are arranged rotationally symmetrically to one another. 15. Vibrating table according to claim 14, characterized in that the four excitation shafts ( 40 a-d) arranged vertically are driven by three-phase asynchronous motors. 16. Vibrating table according to the preceding claim, characterized characterized in that the three-phase asynchronous motors with a Control are connected that one of the motors as master drive and the other motors are regulated as slave drives and that the Control can be programmed so that by overlaying the Four vibrations can be generated with four rotating unbalance forces are.   17. Vibrating table according to claim 16, characterized in that the control can be set so that all four unbalanced shafts ( 40 a-d) revolve with the same phase angle and so a circular vibrating movement is generated. 18. Vibrating table according to claim 14, characterized in that the four Excitation shafts mechanically through a rotating traction mechanism are synchronized with each other. 19. Method of shaking (shaking, vibrating compaction) in one Form to be compacted concrete, characterized in that the form on a vibrating table for circular vibrations in the horizontal table top level is excited. 20. Vibration method according to claim 19, characterized in that the Frequency of the shaking movement is between 0-10 Hz. 21. Use one to create a circular motion designed vibration table for compacting in a mold poured concrete.