EP1590140B1 - Device for moulding mixtures - Google Patents

Abstract

The invention relates to a device for moulding mixtures, preferably concrete mixtures for producing blocks. The device comprises a mould for receiving the concrete mixture, a table, to which the mould is coupled by means of brace elements, a vibration generation system, mounted on the table, for generating harmonic vibrations and for transmitting the latter to the table, a load in the form of a ram for exerting a force on the concrete mixture, first spring elements for elastically supporting the table and second spring elements for elastically supporting the load. A device of this type is equipped with at least eight rotating unbalanced shafts with parallel rotational axes in the vibration generation system. The unbalanced shafts are coupled in pairs for their rotational motion, each pair of unbalanced shafts having a common rotational axis and being driven independently of the other pairs.

Description

Field of the invention

The invention relates to a device for shaping mixtures, preferably of concrete quantities for stone production, comprising a mold for receiving the concrete amount, a table with which the mold is coupled via bracing elements, a vibration generating system attached to the table for generating harmonic oscillations and their transmission to the Table, a load in the form of a punch for applying the concrete amount with a force, first spring elements for elastic storage of the table, second spring elements for elastic storage of the ballast, and refers to the problem of concrete block production by means of harmonic vibration.

State of the art

For the production of small-scale concrete products in industrial production nowadays devices are mostly used, which exploit the principle of shock vibration to compact the concrete amount. In such devices systems are used for vibration generation based on electric motor driven unbalanced shafts, such as in the article "Increasing product quality through efficient compaction" by Berthold Schlecht and Alexander Neubauer, published in the magazine "Betonwert + Fertigteil-Technik", Issue 9 / 2000, pp. 44-52, in detail. At the bottom of the table, on which the receiving mold is stored with the concrete amount, but not firmly clamped, two imbalance shafts or two pairs of unbalanced shafts are attached, in the latter case, the imbalance shafts are mechanically synchronized mechanically by gears or electronically. The recording form is usually made of a so-called range - for example, a board, a plastic plate or a steel sheet - and a molding box, which defines the side walls of the concrete products and rests on the pallet. This has mainly production reasons, since the removal of the finished concrete goods takes place on these pallets, but also significantly influences the behavior of the shock vibration.

However, such devices have disadvantages: for optimum compaction of the concrete, high instantaneous accelerations of more than 200 m / s ² are generally required. With the known devices, however, only imbalance forces of up to 200 kN can be provided, inter alia, because the bearings of the rotating imbalances would otherwise be exposed to unacceptably high loads, along with very short bearing lives. Since the required high accelerations can not be provided by means of the harmonic vibrations generated by imbalance excitation of the table, they must be generated in other ways. This is done with the help of so-called shock vibration. The necessary high accelerations are each briefly generated by so-called bounce between the not firmly interconnected components table, pallet and molding box. The generation of the bounce blows also occurs via knock strips, which are arranged stationary parallel to the table. The setting of these knock strips is purely empirically by the coordination of different machine parameters and thus does not always guarantee the optimum setting and optimal compression. The use of another mixture or another form therefore entails extensive adjustment work. Other disadvantages of the shock vibration are the high noise emissions associated with the bounce blows, the high machine load and high wear of the device. The latter also means that the optimal setting of the machine is lost and the product quality is worse.

If you do not want to miss the shock vibration, the absence of the acceleration peaks generated by the bounce impacts must be replaced by correspondingly higher forces in the harmonic vibration. However, these high forces can not be generated with the known motor-driven unbalance exciters. If, however, instead of motor-driven unbalance exciter one or more hydraulically actuated servo cylinder, so can the required generate high forces and exploit the principle of harmonic vibration. Devices based on hydraulic drive for the production of concrete blocks are also described in the above-mentioned articles by Schlecht and Neubauer as well as in the document WO 01/47698 A1 described. One of the benefits of harmonic vibration is that wear is significantly reduced, noise emissions - the pallet, mold box and table are firmly clamped together - can be reduced, cement consumption reduced and production times reduced.

In the choice of a hydraulic drive medium but also a big disadvantage. Servohydraulik requires an extreme purity of the oil, which can be maintained in the environment of a concrete plant only with great effort. In addition, the energy requirement of a hydraulic-based device is significantly higher than in conventional electric motor-operated shock vibration devices. In addition, the cost of such a servo-hydraulic system are significantly higher than for an electric motor drive.

In Scripture WO 01/47698 A1 Although it is proposed to generate the harmonic vibrations mechanically, but no way is shown to overcome the known and above-mentioned disadvantages of the prior art.

In the EP 0 51 5 305 A1 is in Fig. 2 shown a vibrating device with eight unbalanced shafts. Each two unbalanced shafts are coupled together, each of the unbalanced shaft pairs has its own drive. The vibrating device consists of two vibrating tables. In Fig. 3 The above-mentioned script also describes a two-part vibrating table, but here the eight unbalanced shafts are not coupled, each of the unbalanced shafts has its own drive.

In the DE 38 39 556 A1 a device for the production of concrete parts is described, according to the preamble of Ansprüchs 1. This device has a device for locking a mold with a vibrating table. On each of two opposite sides of the mold frame one of these devices is provided. In the device is a symmetrically formed, driven by a hydraulic multi-link transmission with seven links, which operates on the toggle lever principle. The upward force generated by the hydraulics is transmitted through the joints directed to plungers that press on the mold and press it to the table.

Description of the invention

The object of the invention is therefore to develop a device for compressing mixture, in particular of concrete quantity for concrete block production, based on harmonic vibration, which manages without the disadvantages of shock vibration and the hydraulic drive and yet provides sufficiently high accelerations or forces available.

In a device of the type described above, the object is achieved in that at least eight rotating unbalanced shafts are provided with mutually parallel axes of rotation in the vibration generating system. The unbalanced shafts are coupled in pairs in their rotational movement and each pair of unbalanced shafts has a common axis of rotation and is driven independently of the other pairs. Compared to a conventional device thus an imbalance shaft is replaced by a coupled pair of unbalanced shafts. This inevitably requires that the unbalanced shafts must be constructed squat and shorter. In order to produce the required total force of 600 kN, a force of at least 75 kN must be provided per individual imbalance, which is achieved by a higher imbalance U = m _u r _u , with the imbalance mass m _u and the imbalance radius r _u , compared to conventional unbalanced shafts can be. The transmission of a significantly higher total force is made possible by the fact that eight instead of four unbalanced shafts are used: Since usually each unbalanced shaft is mounted in two mounted on the table bearings, the total force can thus be divided into 16 instead of eight bearings. In this case tension members with hydraulic or pneumatic tension are provided for bracing the form and table as bracing elements. These are attached with their one end to the table and with its other end in the clamped state positively connected to the mold. Alternatively, the tension members may also be attached with one end to the mold and be frictionally connected with its other end in the clamped state with the table. As a result, the pivot point of the tension on the table can be lowered in the height level. The usage of tension members over the conventionally used Verspannhebeln in the amount of the form connections has the advantage that on far projecting parts, as they were previously necessary for the tensioning mechanism, and at high vibration accelerations, as they arise when using harmonic vibrations and resonances, especially against breakage are at risk, can be dispensed with.

In a preferred embodiment of the invention, the tension members are attached with their one end at an angle of more than 0 ° with respect to the perpendicular to the table, preferably at an angle between 10 ° and 30 °. This has the advantage that the tension contours, d. H. the means by which the frictional connection is made, are extended when relaxing from the collision space of the Formhubbewegung and the form can be easily removed and changed.

In a preferred embodiment of the invention are provided as bracing elements at the table wedges and on the form tie rods with matching for the wedges openings, wherein in the clamped state, the wedges are driven into the openings of the tie rods. For the preparation and solution of the tension, a hydraulic or pneumatic forward and reverse drive is expediently provided for the wedges.

In order to reduce wear, it is advantageous to provide for the unbalanced shafts a bending stiffness of EI ≥ 2 * 10 ⁵ Nm ² , where E denotes the modulus of elasticity of the material used for the unbalanced shafts and I the area moment of inertia of the imbalance shaft. The unbalanced steel shaft with a diameter of at least 80 mm is expediently made for this purpose.

In a further embodiment of the invention for mounting the unbalanced shafts mounted on the table mounts are provided with cylindrical roller bearings. In a particularly preferred embodiment, two cylindrical roller bearings are provided with a bearing distance of about 150 mm for the storage of each unbalanced shaft. Cylindrical roller bearings have the advantage of a higher load capacity compared to the commonly used spherical roller bearings. Due to the smaller distance between the roller bearings in conjunction with the higher bending stiffness of the imbalance shafts, the angular deviations in the bearings are minimized, so that the edge load is lower at the camps. The life of the bearings is increased in this way over conventional devices.

The coupling in the rotational movement of two combined unbalanced shafts in a pair can be configured as an electronic clutch, wherein the imbalance shafts are driven synchronized and the synchronization takes place via an electronic control. Easier and cheaper, and therefore preferable, is the pairwise coupling of two unbalanced shafts by means of an elastic coupling. This must be as stiff as possible against rotation, with respect to misalignment, which may occur due to deviations of the current local position of the axes of rotation of both unbalanced shafts to each other in the clutch, but be formed as tolerant. Suitably, the elastic coupling has a torsional stiffness of at least 10 ⁴ Nm / rad and a radial spring stiffness of at most 2 * 10 ⁷ N / m.

The table with shape and amount of concrete can be harmonically vibrated particularly effectively if the vibrations generated by the unbalance exciters with the natural frequency of the vibrating bandage on the first spring elements, which are used for elastic storage of the table, agree: In this case, their resonance can be used , For this purpose, the first spring elements must be carried out in the rule very stiff. This has the disadvantage that in the case of resonance, a significant vibration transfer to the environment takes place. The same situation also applies to the ballast and the second spring elements for elastic mounting of the ballast. However, a good vibration isolation from the environment can be achieved only with soft first and second spring elements. The only usable resonant vibrations would be in this case the mediated by the concrete amount relative movement between the table and ballast. However, the concrete spring acting in this way is heavily dependent on the mixture and the progress of the compression, making it difficult to exploit the resonance.

In a particularly preferred embodiment of the invention, therefore, table and ballast are coupled via third spring elements. Preferably, mechanical or hydraulic springs, each with variable spring forces, are provided as third spring elements. These third spring elements can then be tuned to a predetermined operating frequency, so that changes in the spring force of the concrete spring in the sum of all springs significantly lower impact and even, with variable spring forces of the third spring elements, can be compensated.

As bracing elements also attached to the table electromagnets can be provided. This is of course required that the mold consists of a magnetizable material. This is usually the case since the molds are usually made of steel. If a two-part mold is used, not only the molding box but also the pallet between the molding box and the table must be made of magnetizable material, for example steel sheet. When the magnets are switched on when the mold is lying on, they attract the mold by means of electromagnetic force and clamp it in this way.

Brief description of the drawings

Fig.1

eine Vorrichtung zur Formgebung von Gemengen in einer Seitenansicht,

Fig.2

die Realisierung eines erfindungsgemäßen Verspannungsmechanismus,

Fig.3

eine Unwuchtwelle, wie sie aus dem Stand der Technik bekannt ist, und

Fig.4

ein Paar von gekoppelten Unwuchtwellen entsprechend der Erfindung.

The invention will be explained in more detail with reference to an example. In the accompanying figures shows

Fig.1

a device for shaping mixtures in a side view,

Fig.2

the realization of a tensioning mechanism according to the invention,

Figure 3

an imbalance shaft, as known from the prior art, and

Figure 4

a pair of coupled imbalance shafts according to the invention.

Detailed description of the drawings

In Fig.1 is the basic structure of a device according to the invention for shaping mixtures, in particular for the production of concrete blocks shown. On a table 1 rests a mold 2 containing concrete amount 3. The mold 2 can be made in one piece, but usually bottom and side surfaces of the concrete blocks are defined by different, separable parts of the mold 2, which is made clear in the drawing by a broken line in the mold 2. The side surfaces are defined by a molding box made of steel, to define the bottom surfaces may serve a so-called range, such as a board or a steel sheet, on which the finished concrete blocks can also be removed. Above the mold 2 a load 4 is arranged. On the underside of the table 1 first spring elements 5 are arranged, which serve the elastic storage of the table 1 from the environment. At the ballast 4 second spring elements 6 are mounted, the elastic bearing of the attached elements 6, which serve the elastic bearing of the ballast 4. Table 1 and load 4 are coupled via third spring elements 7. Below the table 1, eight rotating unbalanced shafts 8 are arranged, wherein the unbalanced shafts 8 are coupled in pairs in their rotational movement and each pair of unbalanced shafts 8 has a common axis of rotation. The axes of rotation of the unbalanced shafts 8 extend in Fig.1 perpendicular to the viewing plane. About the rotationally driven unbalanced shafts 8, the table 1 is set with the mold 2 and the concrete amount contained therein 3 in harmonic oscillations. He swings against the ballast 4, which is coupled to the table on the concrete amount 3 and the third spring elements 7 and in turn is also vibrated.

The third spring elements 7 are designed as a function of the concrete quantity so that the resonance of the mutually oscillating system from table 1 and 4 load can be exploited as efficiently as possible over the entire compression process, ie the dependence of the resonant frequency of the compression state of the concrete amount, without the use of third spring elements 7 would be very strong, as far as possible is reduced. The third spring elements 7 must also be designed so that they allow the relative movements that occur between table 1 and 4 Auflast during compression and demoulding. This can be z. B. be realized by means of hydraulic cylinders. Another possibility is, the third spring elements 7 only temporarily, when table 1 and 4 load on each other, is coupled. Here are steel, rubber or air springs.
During the vibration process, the mold 2 is held by bracing on the table. In Fig.1 the bracing elements are designed as hydraulically operated tie rods 9, which are pivotally mounted with its one end to the table about an axis perpendicular to the plane of the drawing. To clamp the mold 2 on the table 1, a pull of the form 2 is applied downward by the hydraulic tie rods 9, for loosening the upper ends of the tie rods 9 are pushed by the hydraulic up and folded out laterally, so that the shape can be easily changed can.

Alternatively, the hydraulically operated tie rods can also be arranged at the same time with a small angle of about 10 ° to 30 ° to the vertical. You then do not have to be folded out laterally, because by the oblique arrangement, the tension contours when relaxing due to the design of the Collision space of the Formhubbewegung be extended and the shape so easier to take out and be changed.

In Fig. 2 another alternative tensioning mechanism is shown. On the mold 2, here designed in one piece, a pull rod 10 is attached. The lower end of the pull rod 10 projects into a recessed area of the table 1 provided for this purpose. The hatched areas of tie rod 10 and table 1 in Fig.2 indicate a cross section through both elements. At the lower end of the tie rod 10 is an opening into which a wedge 11 attached to the table is hydraulically driven. The wedge 11 can be withdrawn by means of hydraulics from the opening of the pull rod 10 and the mold 2 are removed from the table 1.

Figure 3 shows an imbalance shaft 12 of conventional design, as it is not suitable for concrete block production by means of harmonic vibration. The imbalance shaft 12 is driven by a drive 13 which is decoupled from vibrational reasons stored by the table 1. Under the table 1 brackets 14, which are shown here in cross section, mounted with spherical roller bearings 15 for supporting the imbalance shaft 12. In this design, the unbalanced mass and the imbalance forces generated therewith are set narrow limits of up to 50 kN per unbalanced shaft, otherwise the bearings would be exposed to unacceptably high loads, along with very short bearing life.

With the in Figure 4 shown arrangement and execution of unbalanced shafts 8 can be achieved much higher forces. Here are two unbalanced shafts 8 coupled via a flexible coupling 16 to a pair. The drive 13 for the unbalanced shafts 8 is also decoupled for reasons of vibration technology from the table 1 stored. Each imbalance shaft 8 is held by two holders 14 fixed to the table 1 with cylindrical roller bearings 17. The distance between the two cylindrical roller bearings 17, in which an imbalance shaft 8 supports, is about 1 5 cm along the axis of rotation of the imbalance shaft 8.

In this way, a product of imbalance mass and imbalance radius of 0.7 kgm can be realized, so that can be achieved at an excitation circuit frequency of Ω = 2 * π * 60Hz Einzelunwuchtkräfte or exciter force amplitudes of about 100 kN per individual imbalance, without causing the Life of the cylindrical roller bearings 17 would be impaired.

LIST OF REFERENCE NUMBERS

1

table

2

shape

3

concrete mixture

4

ballasted

5

first spring elements

6

second spring elements

7

third spring elements

8th

unbalanced shafts

9

hydraulic pull rods

10

pull bar

11

wedge

12

unbalanced shaft

13

drive

14

bracket

1 5

Spherical roller bearings

16

elastic coupling

17

Cylindrical roller bearings

Claims (13)

1. A device for molding mixtures, preferably concrete mixtures (3), for the manufacture of stone, comprising

   - a mold (2) for receiving the concrete mixture (3),

   - a table (1) to which the mold (2) is coupled via bracing elements,

   - an oscillation-generating system mounted to the table (1) for generating harmonic oscillations and transmitting them to the table (1),

   - a superimposed load (4) in the form of a ram for applying a force to the concrete mixture (3),

   - first spring elements (5) for elastically supporting the table (1), and second spring elements (6) for elastically supporting the superimposed load (4),

   - characterized in that

   - at least eight rotating, unbalanced shafts (8) with mutually parallel axes of rotation are provided in the oscillation-generating system, and

   - the unbalanced shafts (8) are coupled in pairs in their rotary movement, each pair of unbalanced shafts (8) having a common axis of rotation and being driven independently of the other pairs,

   - and traction members with hydraulic or pneumatic traction are provided as bracing elements, having their one end mounted to the table (1) and having their other end connected with the mold (2) in a force-locking manner in the braced condition.
2. Device according to claim 1, characterized in that the traction members are mounted to the table (1) at an angle of more than 0° to vertical, preferably at an angle of between 10° and 30°.
3. Device according to claim 1, characterized in that, as bracing elements, there are provided wedges on the table (1) and tie rods (10) on the mold (2), said tie rods having openings adapted to the wedges (11), said wedges (11) being driven into the openings of the tie rods (10) in the braced condition.
4. Device according to claim 3, characterized in that a hydraulic or pneumatic forward and reverse drive is provided for the wedges (11) to generate and release said bracing.
5. Device according to any one of the aforementioned claims, characterized in that the unbalanced shafts (8) have a bending resistance of at least 2-10⁵ Nm².
6. Device according to any one of the aforementioned claims, characterized in that unbalanced shafts (8) of steel having a diameter of at least 80 mm are provided.
7. Device according to any one of the aforementioned claims, characterized in that supports (14) mounted to the table (1) and comprising roller bearings (17) are provided to support the unbalanced shafts (8).
8. Device according to claim 7, characterized in that two roller bearings (17) with a distance between bearings of approximately 150 mm are provided to support each unbalanced shaft (8).
9. Device according to any one of the aforementioned claims, characterized in that each pair of unbalanced shafts (8) is driven in a synchronized manner by means of an electric coupling.
10. Device according to any one of the aforementioned claims 1 to 8, characterized in that an elastic coupling (16) is provided for coupling pairs of two unbalanced shafts (8).
11. Device according to claim 10, characterized in that an elastic coupling (16) having a torsion spring rigidity of at least 10⁴ Nm/rad and a radial spring rigidity of no more than 2-10⁷ N/m is provided.
12. Device according to any one of the aforementioned claims, characterized in that the table (1) and the superimposed load (4) are coupled via third spring elements (7).
13. Device according to claim 12, characterized in that mechanical or hydraulic springs with variable spring forces are provided as third spring elements (7).

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