Machine for grading ground grain products

Abstract

The machine for grading the ground cereal product is e.g. A plansifter or purification machine. It comprises a plurality of pairs of screen stacks arranged next to one another, each having an upper screen stack (3) and a lower screen stack (4). A drive module (20) is assigned to the screen stack pair, the drive module (20) comprising an electric motor and an inertial weight drivable in rotational movement by the electric motor. A drive module (20) is arranged between an upper screen stack and a lower screen stack of a respective screen stack pair. The upper screen stack pair (3) and the lower screen stack (4) may be substantially equal in size, i.e. The number of screens of the upper and lower screen stacks may be substantially equal or differ, for example, by a maximum of 50% or a maximum of 30%.

Description

Technical Field

[0001] The present invention relates to machines for grading ground cereal products, such as flat sifters or clarifiers. Background Art

[0002] Machines for grading ground cereal products are used to separate the components of the ground product into components of coarse or finer particle size and in some cases also into components of different density and / or for removing foreign bodies from the ground product. The separation of the ground product into components of different particle size is also expressed as "grading" or "classification". Flat sieves are generally used in the milling industry to grade ground cereal products between and after passages through the roller mills of a cereal mill. They can also be applied to so-called controlled sieving, i.e. the sieving of flour ready for sale per se.

[0003] The plansifter comprises a stack of screens acting as a flat screen, which is enclosed in a so-called "screen chamber" or "screen box" with side walls and a cover. These are set into horizontal oscillating movement, in particular circular oscillations in the screen plane, by a drive mechanism.

[0004] According to the state of the art, the drive functions as follows: an even number of screen boxes are coupled to each other and arranged in two rows. A drive module is located between the rows, which drive module comprises an inertial weight which is driven in a circular motion via a belt drive. The screen box group with the drive module is mounted in this context in a suspended manner, so that the inertial weight on the one hand and the center of gravity of the screen box on the other hand together form a flywheel mass system and are offset from each other by up to 180° around a common axis of rotation (orbital axis).

[0005] Firstly, this tried and trusted system has the disadvantage that there must be distances between the rows of screen boxes for the drive modules, which involves a considerable space requirement. Secondly, there is the disadvantage of limited adjustment capabilities: in order to be able to increase or decrease the number of screen boxes, a drive dimensioned for the maximum number of screen boxes must always be used, i.e. the drive is overdimensioned for many applications. Thirdly, the forces when installing such inertial weights are considerable and the requirements are correspondingly high.

[0006] Independent flat screens consisting of a single screen chamber with a single drive are also known. FR 1 426 099 and FR 840 946 each show an embodiment of such an independent flat screen with a drive module which is arranged in the middle, thus between the upper screen stack and the lower screen stack. GB 201013 discloses a flat screen with one or two screen chambers, wherein the drive module is in the middle, wherein, with respect to the embodiment with two screen chambers, there is a common drive module for both screen chambers.

[0007] In EP 2 114 582 it is suggested to provide a separate drive for each sieve chamber so that a flat screen can have not only an even number of sieve chambers but also an odd number of sieve chambers. The drive comprises a drive device on the cover and on the base, respectively, wherein the drive device consists of an annular crown gear which interacts with coils arranged on an outer ring and forms a reluctance motor with these. The inlet opening and the outlet opening are arranged in the interior of the crown gear. This solution allows a flexible arrangement of the sieve chambers. However, the power capacity of the drive unit is limited, and the necessity of a drive unit on the cover and the base makes the design more cumbersome.

[0008] The object of the present invention is to provide a machine for grading ground cereal products, in particular a flat sifter or clarifier machine, which overcomes the disadvantages of the state of the art and which is flexible, robust and simple in design. Summary of the invention

[0009] According to an aspect of the invention, a machine for grading ground cereal products comprises a plurality of screen stack pairs arranged next to each other, each screen stack pair having an upper screen stack and a lower screen stack. A drive module is assigned to each of the screen stack pairs, the drive module comprising an electric motor and an inertial weight that can be driven by the electric motor for rotational movement, i.e. a mass arranged eccentrically relative to the axis of rotation of the rotational movement. In this context, the drive module is arranged between the upper screen stack and the lower screen stack of the respective screen stack pair. The upper screen stack and the lower screen stack may be approximately equally large, i.e. the number of screens of the upper screen stack and the lower screen stack may be equal or differ, for example by a maximum of 50% or a maximum of 30%.

[0010] The machine is, for example, a flat screen or a cleaning machine for separating the ground product from contaminants.

[0011] Screen stack pairs arranged next to one another are mechanically coupled to one another in the context of which they can perform a common, in particular horizontally rotating, oscillation.

[0012] In the present text, "screen stack" means an arrangement of screens arranged on top of each other. In this context, the screens do not necessarily need to be placed on top of each other, but can also be held by an external carrier structure (such as a box) with slide-in grooves for the screens.

[0013] Due to the rotational movement of the inertial weight, the machine is configured to drive the screen elements of the screen stack to oscillate, for example in the form of a circular movement. In the context of the present text, when people talk about "oscillations", these are also to be understood as circular movements.

[0014] The arrangement with the drive module between the upper and lower screen stacks has the advantage that it is distributed in a discrete manner into the inertial weight to the locations where mass forces also occur for each screen stack pair. The force flow is discrete and minimized by this. The necessary bearings are accordingly loaded to a lesser extent and can be dimensioned smaller and / or the service life can be increased. The total weight also becomes smaller, which in turn has a positive effect on the installation. In addition, additional space for a central drive unit between the screen stacks is not necessary. In addition, the procedure according to the invention also allows the machine to be constructed from a virtually arbitrary number of screen stack pairs, wherein the drive is always dimensioned in a suitable manner according to the design, and the energy consumption and material wear are also adjusted to the number of screen stack pairs.

[0015] As known per se, the screen stack can be arranged in a screen box. Alternatively, one can also proceed without using such a closed box by means of screen elements shaped so that they can be stacked on each other and without using an external housing structure.

[0016] The screens of the screen stack are in particular flat screens, ie they are aligned horizontally. The screen plane is therefore in particular parallel to the oscillation plane.

[0017] In particular, the machine is configured to synchronously oscillate the inertial weight of the drive module.

[0018] The drive modules can each comprise a shaft which can rotate relative to a body, such as a housing, and to which inertial weights are fastened. The mounting of the shaft relative to the body can be achieved in a manner known per se by bearings, such as ball bearings, at both end sides of the shaft. The dimensions of the bearings are adapted to the constant load which acts during operation due to the rotating inertial weights thereon and which is significantly smaller than the load on the corresponding bearings of a central drive module according to the state of the art.

[0019] In an embodiment, the shaft is driven directly by the electric motor via its rotor, which is connected to it in a rotationally fixed manner, or is even formed by, for example, a magnetic part of the shaft. Such a solution without gears or other elements converting the rotation speed, such as, for example, belts, etc., is particularly compact and, moreover, particularly low-maintenance.

[0020] The motor may be a synchronous motor, in particular a synchronous motor with permanent magnets. Inner rotor motors as well as outer rotor motors are conceivable, wherein an arrangement with an inner rotor comprising permanent magnets may be particularly efficient.

[0021] The drive modules can each include a plurality of through-channels for the product to be screened. Thus, it is possible for the portions of product envisaged for this purpose to pass from the upper screen stack to the lower screen stack and from there to the positions provided for this purpose. Due to the through-channels, separate devices for guiding through these portions do not need to be present on the screen chamber and / or on the drive modules outside. This facilitates a compact construction.

[0022] Due to the provision of through-going channels, the screen stack pairs form functional units which correspond functionally to screen stacks / screen chambers of flat screens (or purifying machines) according to the state of the art which comprise approximately the same number of screens as upper and lower screen stacks together.

[0023] The through-channels can be placed radially outside the path of the inertial weights in particular. This makes it possible to construct a shaft in which the inertial weights are fixedly fastened to the drive module. The through-channels can be designed as elongated slots. Given the rectangular layout of the drive module, they can extend parallel to the radial outside. The number of through-channels can be, for example, 8.

[0024] A rectangular (eg square) arrangement of the drive modules can be particularly advantageous, since, taking this into account, the drive modules can be arranged next to one another in a simply constructed support.

[0025] Independently of the shape of the drive module, such a common support can be advantageous. It can form the mechanical carrier structure of the machine and also include structures for a suspension device, by which the machine can be suspended (the object here is the part of the machine that is to be driven in circular oscillations, so of course without control components or power electronics). The support can also receive the upper screen stack by placing this on the support directly or indirectly (for example via the drive module on which they are placed), while the lower screen stack is suspended from it.

[0026] Therefore, such a common support usually receives the drive module. Due to this, the drive modules comprise a common mechanical carrier structure and are mechanically coupled to each other. The machine is therefore not only a group of a plurality of individual screens arranged next to each other, but a larger mechanical unit. It was found that, by the concept of having a common mechanical carrier structure (so that each screen stack pair has a centrally arranged drive module), the advantages of the individual flat screens (flexibility) can be combined with the advantages of a larger machine (in particular a higher efficiency), and in particular with always optimized drive power and with minimal space requirements.

[0027] Such a common support is in particular arranged centrally with respect to a vertical line, thus between the upper and lower screen stacks. The drive modules, ie their electric motors and the inertial masses with the housing, are received by the common support. In particular, they can be received by the support in a direct manner, ie they do not rest on the screens of the screen stack.

[0028] Additionally or alternatively, the support can also receive electrical leads for supplying the electric motor, for example in the interior of a frame part forming the support.

[0029] In an embodiment, a plurality of electric motors of a drive module are suspended on a common power stage, i.e. they are supplied by a common power stage. This makes it possible to dispense with power electronics components as well as cables etc. Even if there is a drive module and therefore an electric motor per screen stack pair and therefore more electric motors are required than according to the state of the art, the electric motors can be operated and supplied with a common power stage like a single electric motor per group, which is very economical.

[0030] If there are several electric motor groups and correspondingly several power stages in the machine, the control of the power switches in the power stages can be achieved by a common control module.

[0031] Alternatively, each driver module may have a separate power stage.

[0032] In an embodiment, the machine is configured so that the speed of the electric motor is selectable and can be read out. Thus, by selecting a suitable speed, for example depending on the material to be screened, the screening efficiency can be optimized particularly well.

[0033] In particular, in the case of an embodiment with at least one electric motor group having a common power level, the drive module can furthermore be provided with a mechanical stop which limits movement opposite to the envisaged direction of rotation of the inertial weight (rearward rotation) without preventing movement in the forward direction (envisaged direction of rotation).

[0034] The machine can be configured to perform the following method at startup: First, the inertial weights are moved slowly in the backward direction until they finally appear on the mechanical stop. The motors are therefore first moved backward very slowly and with very little current until the mechanical stop. If the motor is on the mechanical stop, the rotating electric field will continue to rotate and exceed the stall torque. The rotating field rotates further so that the other motors can also rotate further in the direction of the stop. This backward movement occurs until all motors are at their mechanical stops. This can be ensured by the rotating field to withstand a rotation of approximately 360° or more.

[0035] As appropriate, the method may be performed specifically for each power level.

[0036] In particular, the mechanical stop can be formed by a swinging element which can be deflected between an original position and a deflected position relative to the inertial weight. If the swinging element is in the original position, then in the case of a movement in the rearward direction, it appears on the stop element when the inertial weight has reached the angular position defined by the stop element. In the case of a movement in the forward direction, the swinging element is deflected by the inclined portion so that the stop element does not prevent the movement in the forward direction. In addition, the swinging element can be designed so that, taking into account the position of its center of gravity, when the inertial weight rotates sufficiently quickly, the swinging element is deflected by the centrifugal force into the deflected position so that it does not come into contact with the inclined portion in each rotation.

[0037] As an alternative to the previously outlined procedure, alternative ways of aligning the inertial weights are also considered. For example, the motors within the group can be controlled individually using switches ("contactors") instead of using mechanical stops. To this end, the motors will be driven into a defined position (for example in a continuous manner) by encoders or resolvers. In some cases, means (for example friction brakes) can be provided to maintain the position of the motors before the motors are then all driven to perform a synchronous rotational movement with each other (by supplying them with current accordingly).

[0038] Alternatively, for example per drive mass there may be a sensor which detects the position of the inertial weight, for example by means of which it is determined in each case when the inertial weight is directly adjacent to the sensor position.

[0039] In embodiments involving each drive module having its own power stage, such sensor signals may be sufficient for alignment. Synchronization of the rotational movement may then also be achieved during running operation—or in particular during start-up operation.

[0040] In addition to the machine, a method for operating the machine is also a subject of the invention. In addition to providing a machine as defined above, the method comprises, with or without the specific features of an embodiment of the invention, a step of synchronously driving the inertial weight of the drive module in order to drive the sieve chamber to oscillate. For this purpose, the machine - or more precisely the mechanical coupling unit of the sieve stack and the drive motor and possibly the support (without the control components and power electronic components of the machine) can be mounted or suspended so that it can oscillate in a horizontal circle.

[0041] Optionally, the method further comprises the step of starting the machine by means of inertial weights which, on start-up, first move slowly rearwards until they reach a mechanical stop and only subsequently are driven by their electric motors into a rotational movement in the forward direction. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In the following, examples of embodiments of the present invention are described by means of the figures. In the figures, the same reference numerals denote equal or similar elements. The figures show elements that partially correspond to each other in size, the size being different from figure to figure. In the following, it is shown:

[0043] Figure 1 : View of the flat screen;

[0044] Figure 2 :according to Figure 1 A view of a planscreen with the screen stack partially removed and with two drive modules removed;

[0045] Figure 3 : Lower view of the bracket;

[0046] Figure 4 :Used according to Figure 1 A view of a drive module of a flat screen;

[0047] Figure 5 : Figure 4 A plan view of the drive module;

[0048] Figure 6 : Figure 4 and Figure 5 An illustration of a cross section along plane VI-VI of a driving module;

[0049] Figure 7 and Figure 8 : Detail of the drive module with two different positions of the swing tab;

[0050] Fig. 9 :according to Figure 1 A schematic diagram of the electric motors of the eight drive modules of the flat screen; and

[0051] Fig.10 : Multiple possible arrangements of screen stack pairs. DETAILED DESCRIPTION

[0052] Figure 1 The flat screen 1 is shown when used in a grain mill. Figure 2 The planscreen is shown with the screen stacks partially removed and the drive module partially removed. The planscreen comprises a plurality of upper screen stacks 3 and lower screen stacks 4, which are only schematically shown, which are assembled via a common suspension device so that a common horizontal swinging movement is possible. Furthermore, the planscreen comprises a flexible supply duct as screen material inlet and an equally flexible outlet duct as screen material outlet. Figure 1 In the figure one sees an upper inlet 6, to which the supply duct is connected, and a lower outlet 7 for the outlet duct. As an alternative to a configuration without an additional outer sieve chamber housing, a sieve stack 3, 4 can also optionally be present in each sieve box.

[0053] The support 11 serves as a mechanical carrier structure. It forms a carrier frame and receives drive modules, which are described in more detail below. The screen stack is fastened to the drive modules and thus indirectly to the support 11, for example by a clamping system of rods and / or belts and / or other means; the clamping system is not Figure 1 and Figure 2 Medium picture.

[0054] The support 11 may comprise a fastening structure 12 for the suspension means, which is formed, for example, in a manner known per se, by a flexible rod. Furthermore, it may form a cable supply for the drive module 20, i.e. the support 11 may also receive electrical leads, for example in a hollowed-out portion in the interior of the element forming the carrier frame.

[0055] For example, one can also, in particular, Figure 3 As seen in the lower view of the support 11 of FIG. 1 , the support is essentially open. It comprises a bracket 13 on which the drive modules 20 can be placed and against which they can also be fastened. The brackets 13 are arranged so that the drive modules 20 are placed on them in the region of the lower corners of the bracket.

[0056] exist Figure 3 Also visible in FIG. 1 is the possibility of an electrical supply 18 , which connects the electric motor of the drive module 20 to a supply duct in the support 11 and which is guided here along the underside of the drive module.

[0057] Figure 4 The drive module 20 is shown in an oblique view from above. The drive module, which is defined by the housing 22, has a rectangular, in particular substantially square, layout. For the function to be effective, an inertial mass 23 is important, which is constructed here from a plurality of plate elements 24 (other embodiments, such as a monolithic or other component embodiments are also possible) and which can be driven in a circular motion by an electric motor (which is described in more detail below). The direction of rotation 28 is Figure 4 The block arrows are shown in FIG. 1 and the rotation axis 29 is also shown in FIG. Figure 4 . In this text, terms such as "radial", "axial" etc. refer to this axis of rotation 29, insofar as a different meaning is not explicitly indicated. Of course, the way the invention functions does not depend on the direction of rotation. The direction of rotation and everything that this involves can also be reversed, wherein then a mechanical stop (which is described in more detail below) would then possibly be installed at the other side. The direction of rotation can be configurable, for example.

[0058] The drive mass 20 also comprises eight through-channels 25, along each side, outer through-channels and inner through-channels 25. All through-channels 25 and therefore also the inner through-channels are arranged radially outside the path described by the inertial weight 23. The inertial weight is constructed so that it has a large mass and is arranged as far to the outside as possible within the space available to it, which is why it has approximately the shape of a ring segment, the axial (vertical) extension of which corresponds substantially to the completely vertical extension of the drive mass.

[0059] exist Figure 4 In the figure, one can also see the swing lug 41 and the stop plate 42, which are used to bring the inertial weight 23 into a defined position before the start operation, which will be described below by Figure 7 and Figure 8 Explain in more detail.

[0060] Figure 5 The drive module is shown in a view from above, and Figure 6 Shown through Figure 5 In addition to the through-channel 25, Figure 6 In particular, one sees the shaft 31 which is rotatably mounted relative to the housing 22 by means of a retainer 33 with respective ball bearings 32 at the upper and lower sides. The inertial weight 24 is fastened to the shaft 31 (fastening means 34).

[0061] The shaft 31 is connected to the rotor of the electric motor in a direct manner (i.e. without gears, belts, gear wheels or other transmission means that could convert the rotation speed), or forms the rotor. In the illustrated embodiment, permanent magnets 35 attached to the shaft 31 at the outside form the rotor of the electric motor, while a stator 36 with coils and soft magnets for generating a magnetic rotating field is fastened to the housing.

[0062] Figure 7 and Figure 8 The possibility of bringing the inertial weights into a defined position before the machine is started is shown. This may be necessary, for example, if in the event of an interruption in operation the inertial weights of different drive modules end up at different distances. If the inertial weights 23 of the drive modules 20 are brought into a defined position in a common procedure before starting, synchronous operation is possible, and in particular even if a plurality of motors are operated with a common power stage (with a common power electronic converter).

[0063] For this purpose, a swinging tab 41 is fastened to the inertial weight 23, said swinging tab interacting with a stop plate 42, in the case of a slow backward rotation (corresponding to Figure 7 and Figure 8 to the observer) so as to form a stop without preventing movement in the opposite forward direction (in Figure 4Rotation in the direction of rotation 28).

[0064] The swing tab is mounted pivotably about an axis 43 . Figure 7 The state is shown in which the end 44 of the swinging tab abuts against a stop 45, which is formed by a stop plate 42 - this can be fastened, for example, to a Figure 7 and Figure 8 Move back more than the Figure 7 The location is impossible.

[0065] In contrast, the forward movement is not blocked by the stopper plate 42 because the radially inner narrow side of the stopper plate 42 forms an inclined portion 48 which deflects the swing tab 41 in the event of movement in the forward direction.

[0066] In order that the tip 44 of the swing tab 41 does not come up on the inclined portion 48 in each revolution and the swing tab deflects in the case of a rapid rotation in the forward direction, the center of gravity of the swing tab 41 is arranged below the axis 43. In the example shown, this is achieved by a weight portion 47 of the swing tab 41 below the axis 43. If the inertial weight is stationary or only moves slowly, the swing tab 41 is tilted according to Figure 7 Vertically aligned. Under fast rotation, centrifugal force is achieved Figure 8 4. The deflection in the position depicted in FIG. 4 shows that the tip 44 of the swing tab is radially inside the stop plate 42 and does not contact the stop plate 42 at any point in time.

[0067] The machine can now be programmed so that at start-up it can first slowly move the motors in the rearward direction for at least about a full revolution so that all the inertial weights are securely pressed against the stops. They are then all in a defined position. The motors are then all brought into rotation in the forward direction in a synchronized manner.

[0068] Fig. 9 The principle of supplying several of the motors 51 of different drive modules via a common power stage 53 is shown. Fig. 9 8 motors are shown, wherein each motor belongs to one of the drive modules 20 and is a synchronous motor, for example, as shown by a rotor having at least one permanent magnet 35. Figure 6 Described. Fig. 9 In the embodiment of the invention, four motors are assigned to one of the two power levels 53 and thus form a common motor group - with regard to closed-loop control technology, they correspond similarly to a single motor. In operation, the motors with a common power level 53 themselves run synchronously by the same rotating field generated in each of the motors and the rotor following this rotating field.

[0069] The power switches in the power stages 53 are controlled by a common control module 52. For the absolute position, the common control module 52 comprises a position sensor for each power stage 53.

[0070] When physically realizing the machine, and as an alternative to the depicted configuration, the controller may also be an integral part of the power stage 53 .

[0071] In an embodiment, the machine is configured to precisely specify the speed and also display the speed for this purpose through the control module 52. The screening efficiency can be optimized by selecting the appropriate speed.

[0072] exist Fig. 9 An input and / or output unit 55 is schematically drawn in, via which the speed can be set and from which the speed can be read. The input and / or output unit 55 is Fig. 9 Schematically shown in FIG is a computer which communicates with the control module via an interface. However, other solutions are also conceivable, such as an operating panel on the control module, an operating element with readout possibility (slide control, knob).

[0073] One advantage of the approach according to the invention which has already been mentioned above is the fact that the number and arrangement of screen stack pairs can be configured essentially freely and also an uneven number of screen stack pairs is possible. Fig.10 Various possibilities are shown. Each of the Figures AI schematically illustrates an arrangement of a screen stack pair 3, 4 and furthermore shows a possible position of a fastening structure 12 for a suspension device.

[0074] According to arrangement A, the machine may comprise only a single screen stack pair. Arrangements BD show 2, 3 and 4 screen stack pairs, respectively, arranged in a row, and longer rows are also conceivable. Arrangements EH each comprise two rows of screen stack pairs. One can also see that, contrary to the state of the art, a distance between adjacent rows is essentially unnecessary, whereas in the state of the art, drive modules are generally present between two rows, which is why these need to be at a greater distance from each other, as is also the case in arrangement I, for example. Arrangements with two (or even more) rows and with a greater distance between the rows, such as Figure 1 Each row also has a ratio Fig.10 Fewer or more screen stack pairs than those shown in the figure are also an option for the machine according to the invention. If necessary, the space between the rows can then be used in a suitable manner, since it does not require larger drive modules spaced horizontally from the screen stack pairs, as is the case in the screen stacks in the state of the art.

[0075] Many other arrangements are conceivable. For example, in Figure 3In the case of the support illustrated in the figure, a single position can also remain vacant. Alternatively, an arrangement with three rows of screen stacks or even an irregular arrangement is conceivable if the suspension is adjusted accordingly.

Claims

1. A machine for grading ground cereal products, comprising a plurality of screen stack pairs, the screen stack pairs being arranged next to each other, the screen stack pairs each having an upper screen stack (3) and a lower screen stack (4), and a drive module (20) each between the upper screen stack (3) and the lower screen stack (4) of the plurality of screen stack pairs, wherein: Each of the drive modules (20) includes an electric motor and an inertial weight (23) that can be driven by the electric motor to perform rotational movement.

2. The machine according to claim 1, configured to drive the inertial weights (23) of the drive modules (20) synchronously.

3. A machine according to claim 1 or 2, wherein: The drive modules (20) each comprise a shaft (31) rotatable relative to a base body, wherein the electric motors each comprise a stator (36) and a rotor (35), and wherein the rotor (35) is connected to the shaft (31) or is formed by the shaft (31) in a rotationally fixed manner.

4. A machine according to any one of the preceding claims, wherein: The electric motor is a synchronous motor with permanent magnets.

5. A machine according to any one of the preceding claims, wherein: The drive modules (20) each comprise a plurality of through-channels (25) through which portions of ground cereal product can pass from the upper sieve stack (3) to the lower sieve stack (4).

6. A machine according to any one of the preceding claims, wherein: The drive modules (20) each include a housing (22) having a rectangular, in particular square, layout.

7. Machine according to any one of the preceding claims, comprising a support (11) in which the drive module (20) is received.

8. The machine according to claim 7, wherein: The support (11) comprises a fastening structure (12) for a suspension device for suspending the machine, and wherein: The upper screen stack (3) is placed directly or indirectly on the support (11), and the lower screen stack (4) is directly or indirectly suspended on the support (11).

9. A machine according to claim 7 or 8, wherein: The bracket receives electrical leads for supplying an electric motor of the drive module (20).

10. A machine according to any one of the preceding claims, wherein: The electric motors (51) of a plurality of drive modules (20) are supplied by a common power stage (52).

11. Machine according to any of the preceding claims, configured to move the inertial masses, at start-up, in a direction opposite to the envisaged direction of rotation until they come upon a mechanical stop and only then to bring them into rotational movement in the envisaged direction of rotation.

12. The machine according to claim 11, wherein: The mechanical stop is formed by a swinging element which, in the event of a rotational movement of the inertial weight in the envisaged direction of rotation, is deflected from a basic position into a deflected position in which it does not inhibit the rotational movement.

13. A machine according to any one of the preceding claims, wherein: The speed of the inertial weight (23) is selectable and wherein the machine is configured such that the speed can be read out.

14. A method for operating a machine according to any one of the preceding claims, wherein: The inertial weight of the drive module is brought into synchronous rotational movement, while the unit with the screen stack and the drive module is mounted so that they can oscillate horizontally in circles.

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