Vibratory conveyors and methods for conveying bulk materials

Abstract

The invention relates to a vibration arrangement with a vibrating machine, which has a conveying trough (1) arranged along a longitudinal direction (L) for receiving bulk material and a drive system (2) for generating a vibrating motion of the conveying trough (1). According to the invention, a damping system (10) is provided for at least partial compensation of dynamic forces acting on a foundation (9), which consists of at least two rotatably arranged unbalanced drives (12).

Description

The present invention relates to a vibration arrangement having a vibration machine which has a conveying trough arranged along a longitudinal direction for receiving bulk material and a drive system for generating a vibration movement of the conveying trough.In such vibration arrangements, a conveying trough is set into a vibration movement via the drive system, so that as a result the bulk material arranged thereon is set into movement with each vibration.The vibrating machines can be provided, for example, exclusively for conveying bulk material, wherein such a vibrating conveyor then throws the bulk material over a comparatively small distance along the longitudinal direction with each vibration. Such a throw is therefore also referred to as a micro throw, wherein the conveying process is a sequence of a plurality of microturns arranged one behind the other.In order to realize a conveying process with the aid of such a micro throw, the drive exciter force must act obliquely on the conveying trough, wherein the oblique position is decisive for the throw angle of the micro throw. Against this background, this oblique position is also referred to as the angle of attack, wherein the magnitude of the angle of attack is obtained in particular on the basis of the material to be conveyed.Alternatively, vibrating machines of the type in question of vibration arrangements can also be designed as a screening machine with a conveying trough designed as a vibrating screen, wherein the bulk material is then classified in the course of the vibration. Combinations are of course also conceivable, wherein both classification and conveying of the classified bulk material then take place in a corresponding vibrating machine.For driving such oscillating machines, thrust crank, magnetic or imbalance drives are usually used. The VDI Directive 2333 provides a systematic listing of the embodiments. A vibratory machine with a push crank drive is shown, for example, in DE 20 2013 004 050 U1.Regardless of the specific embodiment of the vibratory machine, accelerations greater than the falling acceleration are required due to function. The machine identification number K is used to identify the acceleration. The machine code indicates the ratio of the maximum acceleration to the falling acceleration. In the normal case, oscillating machines operate with machine characteristics K<5, in special cases values up to approximately K=10 can also be achieved. In conjunction with the mass of the oscillating conveyors, this results in large mass forces which can be transmitted to the environment only in exceptional cases. Usually, however, vibration isolation is performed to reduce the forces introduced into the foundation.Within the scope of the invention, the foundation is the substructure on which the vibration arrangement is set up. These can usually be concrete foundations, a concrete slab, a steel frame structure or other types of support structures.In such a case, the vibrating machine is then not placed directly on the foundation, but rather is supported on the foundation via elastic spring elements. The vibratory machine can be designed as a single-mass system, two-mass system or multi-mass system. In a two- or multiple-mass system, the forces transmitted to the foundation are already reduced within the vibrating machine by the relative movement of the masses with respect to one another.A two-mass system has in principle proved its worth in practice and also makes possible a certain compensation of the dynamic forces transmitted to the foundation.DE 891 974 B describes how the dynamic forces can be reduced with the aid of a mass balance. The drive system is arranged between the conveying trough and a countermass and brings about a movement of the masses in the opposite direction, whereby the mass forces are ideally completely compensated. The counter mass is connected to the foundation via spring elements and thus forms the displacement of the vibrating machine. The movement of the countermass deforms the spring elements accordingly, whereby dynamic forces are produced which are transmitted to the foundation. While the movement of the conveying trough is predefined as a function of the function, the movement of the countermass can be kept as small as possible by selecting the countermass to be very large.For this purpose, DE 1 013 221 B proposes pouring out the countermass with concrete, as a result of which a mass ratio of conveying trough and countermass of 1:4 is achieved. A disadvantage of this is that the overall machine weight thereby increases extremely. In this construction, the swinging movement of the counter mass resting on the elastic stay springs becomes small and thus also the dynamic forces introduced into the foundation.DE 4 232 010 A1 proposes placing the placement points of the vibrating machine into the movement nodes which arise when two masses move in opposite directions. Ideally, this is achieved in that no dynamic forces are introduced into the foundation. In this respect, it is also customary to fasten these vibrating machines to the foundation without elastic set-up springs at the movement nodes by means of a rigid connection. This type of vibrating machine is, however, very sensitive to mass couplings which are produced by the bulk material to be conveyed and, particularly in the case of a rigid connection, lead directly to the introduction of dynamic forces into the foundation.When using elastic spring elements for setting up the vibrating machine, the dynamic forces at the set-up points are introduced substantially perpendicularly into the foundation. Due to the transverse rigidity of the spring elements, force lines with a direction inclined relative to the vertical are also possible as a result of the non-vertical movement of the vibratory machine. In the case of vibrating machines with circular or elliptical vibrating movements, elliptical foundation loads are also possible.The object of the invention is to specify a vibratory machine which enables particularly flexible compensation of the dynamic loads.The object and solution of this object is a vibratory machine according to claim 1. Accordingly, a damping system is provided for at least partially, but preferably completely compensating the dynamic forces acting on the foundation, which consists of at least two rotatably configured imbalance drives.With the aid of the rotatably configured imbalance drives, it is possible to generate an oscillating compensation force, the magnitude, frequency and direction of action of which is determined on the basis of the oscillation of the oscillating machine, in particular of the conveying trough. The compensating force is adjusted in its time-dependent course such that it counteracts the dynamic foundation force of the vibratory machine and thus the remaining total dynamic force introduced into the foundation is as small as possible and in the ideal case assumes the value zero.The damping system according to the invention can be adjusted and controlled particularly flexibly on account of the imbalance drives, so that rapid and effective damping can always take place depending on the operating point. Accordingly, the dynamic residual forces which are transmitted to the environment via the foundation can be minimized.A particularly preferred embodiment provides that the foundation is designed as an uprighting device, in particular as a transportable uprighting device. In particular, this is a frame structure, e.g. a steel frame structure. The damping system and at least the conveying trough, but in particular the entire vibrating machine, are then arranged on the common setting-up device.The at least two imbalance drives can furthermore be configured to rotate in the same direction or to rotate in opposite directions. The rotation in the opposite direction makes it possible for in particular the revolving forces generated by the individual imbalance drives to compensate one another in one direction, as a result of which a linearly oscillating compensation force is generated.A rotation in the opposite direction is also particularly expedient if the at least two imbalance drives form a common damping unit. According to such a configuration, a plurality of damping units, e.g. two, three, four or more, can then also be provided, which are preferably arranged one behind the other in the longitudinal direction. In particular, the damping units are arranged on the plane of symmetry or in rows symmetrically to the plane of symmetry of the vibrating machine in the longitudinal direction.Alternatively, the damping system can also have an odd number of imbalance drives, for example three, five, seven or more. The imbalance drives are preferably arranged one behind the other in the longitudinal direction and are configured to be rotatable alternately in the opposite direction.The imbalance drives can preferably all be arranged on a horizontal plane, wherein this means that the axes of rotation of all imbalance drives lie in a common horizontal plane. Of course, however, it is also within the scope of the invention for the imbalance drives to be arranged in different horizontal planes.Preferably, the conveying trough, in particular the entire vibrating machine, can be supported on the foundation via at least two support struts arranged one behind the other in the longitudinal direction. The support struts are preferably spring elements.Starting from such a configuration, each support strut can then be assigned an imbalance drive or else a damping unit in order to compensate for the dynamic forces directly at the introduction points. Within the scope of the invention, an assignment means that a compensation force generated by the imbalance drives can generate an action line which is introduced directly on the support strut. This ensures that the compensation force is generated where support is also provided on the foundation.However, it can of course also be provided within the scope of the invention that the imbalance drives or the damping units are not directly assigned to a support strut. In this case, the imbalance drives or the damping units are distributed along the longitudinal direction in order to enable a distribution of the force application points. In this case, the distribution takes place such that all imbalance shafts are parallel to one another and are perpendicular to the plane of symmetry of the oscillating machine formed in the longitudinal direction. The positioning and the distances of the imbalance shafts are selected such that no resultant tilting moment arises and the line of action of the resultant compensation force corresponds to the line of action of the resultant dynamic foundation force of the vibratory machine.In principle, it is sufficient within the scope of the invention if the conveying trough is supported on the foundation via at least two support struts. However, it is also possible to provide more than two support struts, e.g. three, four or more, one behind the other in the longitudinal direction. This is particularly useful in the case of long and / or particularly heavy delivery troughs. In addition, a plurality of support struts can also be provided along the transverse direction. In particular, it is provided in this regard that a first and at least a second group of support struts arranged one behind the other in the longitudinal direction are provided in the width direction of the conveying trough.In the following, in the design and arrangement of the imbalance drives, reference is always made to a group of imbalance drives, wherein the designs can of course also be transferred to two or more groups, wherein all groups are then of identical design.Preferably, each support strut is assigned at least two imbalance drives, which form a common damping unit of the damping system. Accordingly, the compensation force is generated on this support strut by the movement of at least two imbalance drives, wherein the compensation force is accordingly dependent on the direction of rotation and the phase position of the imbalance drives of a damping unit. The balancing drives each have an imbalance rotatable about an axis of rotation. The axis of rotation is preferably arranged in the width direction of the conveying trough.The imbalance drives of a damping unit and / or all imbalance drives of the damping system are preferably designed and configured such that they generate a compensation force of equal magnitude. Accordingly, the imbalance drives of a damping unit and / or all imbalance drives of the damping system have the same imbalance. The imbalance of the imbalance drives can be formed either via an eccentrically selected imbalance shaft or via imbalance masses arranged on an imbalance shaft.Of course, however, it is also within the scope of the invention that the imbalance drives differ from one another at least partially with regard to their imbalance. In particular in the case of an odd number of imbalance drives of the damping system, the outer drives have a smaller imbalance than the inner drives in each case. In particular, the imbalance of the outer drives is halved in comparison with the imbalance of the inner drives.It is also possible for the imbalance drives, in particular the imbalance drives of a damping unit, to rotate with a phase offset. Since in particular the phase offset can be adjusted during operation, a rapid and flexible adjustment is possible not only between the imbalance drives of the various support struts but also within a damping unit.The phase offset here denotes the time offset at which the imbalance of the imbalance drives respectively pass a specific reference position, for example the perpendicular below the respective shaft center point. In this position, a corresponding pick-up can be attached to each imbalance drive, which pick-up detects the passage of the reference position. With respect to one revolution, the individual pick-ups detect the passage of the reference position at different time intervals, as a result of which the phase offset can be determined. To set the phase offset, the imbalance of the individual imbalance drives can then be adjusted via a control or regulation.Starting from an embodiment with damping units, the assignment to individual support struts is determined on the basis of the compensation force generated by the imbalance drives of a damping unit.Furthermore, the imbalance can also be adjustable before and / or during operation, so that the control of the vibratory machine can be carried out in a particularly flexible manner.The advantage of the damping system according to the invention is above all that the rotatably configured imbalance drives can have an adjustable phase offset, wherein with the aid of this phase offset the acting compensation force can be adjusted both in magnitude and in the direction of action. Elliptical encircling compensation forces can also be realized in this way.According to a preferred embodiment, the adjustment is effected in that all imbalance drives of the damping system or of a damping unit, which have a common first rotational direction, are adjusted with a second rotational direction with respect to the imbalance drives that can rotate in opposite directions. Alternatively, all imbalance drives of one damping unit can also be adjusted with respect to the imbalance drives of another damping unit.For adjusting the phase offset, a control and / or regulating unit is preferably provided, which correspondingly brings about the adjustment of the imbalance.Furthermore, it can be provided that the conveying trough is connected to an insulating frame, wherein the insulating frame again connects to the foundation via the support struts. If the support struts are designed as spring elements, they form a first spring arrangement. The conveying trough then preferably connects to the insulating frame via a second spring arrangement.A part of the dynamic forces generated by the conveying trough can already be compensated by the insulating frame before they are passed on to the foundation.The drive system of the delivery trough and / or of the damping system is formed in particular by electric motors, in particular asynchronous motors.The drive system of the conveying trough can be arranged, for example, directly on the conveying trough. In this case, the drive system is also formed from unbalanced drives which can rotate in opposite directions and whose axis of rotation runs parallel to the desired angle of attack.Alternatively, the drive system of the conveying trough can also be a crank drive. In this case, the direction of action of the oscillation is substantially effected by link springs which are arranged between the conveying trough and the foundation or between the conveying trough and the insulating frame. The crank drive can be connected to the conveying trough via a third spring arrangement in order to decouple the movement of the conveying trough from the movement of the crank drive by a certain distance.The drive system of the damping system is preferably arranged directly on the foundation. However, it is also conceivable to drive the imbalance drives of the damping system via a coupling device, so that the drive system can be arranged outside the foundation.According to a preferred embodiment, the conveying trough can have a closed base for conveying bulk material. Accordingly, with the aid of the vibrating machine, only a conveyance of the bulk material takes place from one point of the conveying trough to another point of the conveying trough. Alternatively, the bottom can also have a plurality of perforations, so that not only conveying but also screening of bulk material is then made possible.The subject matter of the invention is furthermore a method for conveying bulk material according to claim 14 with an oscillating machine according to the invention, wherein bulk material is applied to the conveying trough and is set in motion under an oscillating movement of the conveying trough, and wherein the damping system at least partially compensates the forces generated by the conveying trough by rotating the imbalance drives. Accordingly, the imbalance drives of the damping system are thus operated in order to generate a compensation force.According to a preferred method, the compensation force can be generated by imbalance drives rotating in opposite directions and / or in the same direction. In particular, two imbalance drives, in particular counter-rotating imbalance drives, each form a damping unit, wherein imbalance drives of two damping units, which are preferably adjacent to one another in the longitudinal direction, rotate in the same direction.If the imbalance drives are not combined to form damping units, all imbalance drives preferably rotate alternately in opposite directions in the longitudinal direction.In the embodiment in which in each case two imbalance drives are combined to form a damping unit, imbalance drives of two damping units adjoining one another in the longitudinal direction preferably rotate in the same direction. Accordingly, adjoining damping units can be operated mirror-symmetrically to one another.A further development of the method provides that the bulk material is transported and / or classified along the longitudinal direction as a result of the oscillating movement of the oscillating chute.In addition, the imbalance drives can rotate at least partially with a phase offset with respect to one another, wherein the damping system can be adjusted before and / or during operation by changing the phase offset.The invention is now explained in more detail below with reference to an exemplary embodiment. The following are shown: FIGS. 1, 2 show schematic representations of oscillating machines from the prior art, FIG. 3 is a longitudinal view of a vibratory machine with a damping unit, FIG. 4 shows the vibratory machine according to FIG. 3 in a transverse view, FIG. 5 is a longitudinal view of an alternative swing machine with imbalance drives on each support strut, FIG. 6 shows the vibratory machine according to FIG. 5A in a transverse view, FIGS. 7A, 7B are longitudinal views of an alternative vibratory machine with damping units on each support strut at two different operating points, FIG. 8 shows a longitudinal view of an alternative vibrating machine according to FIGS. 7A, 7B, FIG. 9 is a longitudinal view of an alternative swing machine with an odd number of imbalance drives, FIG. 10 shows a longitudinal view of a vibratory machine according to FIG. 7A in an oblique placement.FIGS. 1 and 2 show vibratory machines from the prior art, each having a conveying trough 1 arranged along a longitudinal direction L for receiving bulk material, a drive system 2 for generating a vibratory movement of the conveying trough 1 and having supporting struts 3 for placing the vibratory machine on a foundation 9, wherein the foundation 9 is designed in this case as a concrete plate.The oscillating machines shown in FIGS. 1 and 2 have a drive system 2 which differs from one another, wherein according to FIG. 1 two unbalanced drives which are rotatable in opposite directions and are not shown in more detail are provided, which have an axis of rotation 4 which is arranged obliquely to the longitudinal direction L. The exciter force generated by the drive system 2 with the axis of rotation 4 acts at an angle of attack α with respect to the longitudinal direction L.In contrast, the drive system 2 according to FIG. 2 is designed as a crank drive, which acts on the conveying trough 1 via a spring arrangement 5.The crank drive is set up on an insulating frame 6. Furthermore, link springs 7 are arranged between the insulating frame 6 and the conveying trough 1, which are likewise arranged at an angle β with respect to the insulating frame 6 and with respect to the conveying trough 1 and specify a direction of oscillation of the conveying trough 1, so that here too a conveying of the bulk material in the longitudinal direction L can be effected.In both cases, the vibrating machines shown in FIGS. 1 and 2 generate a vibrating movement of the conveying trough 1, which correspondingly, in the erected state of the vibrating machine, lead to dynamic force effects on the foundation 9. By using support struts 3, these dynamic loads are reduced. According to the invention, the remaining dynamic loads are further reduced by damping units 11 arranged on the foundation 9.FIGS. 3 to 10 show embodiments according to the invention of the vibrating machine with an active damping system 10.FIGS. 3 and 4 show a vibratory machine in various views, wherein the damping system 10 consists of a damping unit 11 which is formed from two imbalance drives 12. The imbalance drives 12 of a damping unit 11 are designed to be rotatable in opposite directions and serve to at least partially compensate for the dynamic foundation forces generated by the conveying trough 1. For this purpose, the damping unit 11 is set up on the foundation 9 in the vicinity of the line of action of the resultants of the dynamic foundation forces. The shafts of the imbalance drives 12 are perpendicular to the plane of symmetry of the oscillating machine. In order to generate a perpendicular compensation force, a different orientation of the imbalance drives 12 of a group arranged parallel to one another in the installation plane is also possible.FIG. 6 shows an alternative arrangement with two groups of imbalance drives 12 which are spaced apart from one another in the transverse direction and wherein the imbalance drives 12 of one group are spaced apart from one another by a large distance. The imbalance drives 12 are arranged in the vicinity of the front and rear support struts 3.Direct local assignment is also possible with respect to the transverse direction Q, wherein, according to FIG. 6, the imbalance drives 12 project in the transverse direction with respect to the spring elements 14.According to FIGS. 4 and 6, the imbalance drives 12 are each formed with 2 imbalance masses 15 a, 15 bon the imbalance motor shaft. This is the construction of an imbalance drive 12 known from the prior art. The imbalance masses in turn consist of imbalance disks that can be rotated relative to one another, whereby the total imbalance acting can be adjusted, in particular, in the stationary state. Of course, the imbalance masses 15 a, 15 bmay also be designed as an imbalance mass.According to FIGS. 5 and 6, an imbalance drive 12 is attached to each installation point of the oscillating machine.FIGS. 7A and 7B show an embodiment with two damping units 11 arranged one behind the other in the longitudinal direction L. As a result, a surface distribution of the compensation force can be carried out in the case of long conveying troughs 1. The size of the imbalance and the distances between the damping units 11 and between the imbalance drives 12 of each damping unit 11 are selected such that no rotational angle-dependent tilting moment is generated.FIGS. 7A and 7B also differ in operating point. According to FIG. 7A, a phase position with a perpendicular line of action of the compensation force is provided, and according to FIG. 7B, a phase position with an inclined line of action of the compensation force is provided.Whereas, according to FIGS. 7A and 7B, each support strut 3 is assigned a damping unit 11, FIG. 8 shows an embodiment with a total of four damping units 11, wherein the damping units 11 are not directly assigned to a support strut 3.FIG. 9 shows an embodiment with an odd number of imbalance drives 11 a, 11 b, wherein the outer imbalance drives 11 ahave a smaller imbalance than the inner imbalance drives 11 b. Furthermore, the imbalance drives 11 a, 11 bare configured to be rotatable alternately one behind the other in the longitudinal direction L.FIG. 10 shows an alternative placement of the vibrating machine according to FIG. 7A of the damping units in parallel horizontal planes. This arrangement is useful when the vibrating machine is set up at an inclination, which is frequently chosen in the case of screening machines.

Claims

Vibration arrangement with a vibration machine, which has a conveying trough (1) arranged along a longitudinal direction (L) for receiving bulk material and a drive system (2) for generating a vibration movement of the conveying trough (1), characterized in that a damping system (10) is provided for at least partially compensating dynamic forces acting on a foundation (9), which damping system consists of at least two rotatably configured imbalance drives (12).Vibration arrangement according to Claim 1, characterized in that the foundation (9) is designed as a transportable mounting device.Vibration arrangement according to Claim 1 or 2, characterized in that the at least two imbalance drives (12) are designed to be rotatable in opposite directions.Vibration arrangement according to one of Claims 1 to 3, characterized in that the at least two imbalance drives (12) together form a damping unit (11) of the damping system (10).Vibration arrangement according to Claim 4, characterized in that the damping system (10) is formed from at least two damping units (11).Vibration arrangement according to one of Claims 1 to 3, characterized in that the damping system (10) has an odd number of imbalance drives (12), the imbalance drives (12) being configured such that they can be rotated alternately in the opposite direction in the longitudinal direction.Vibration arrangement according to one of Claims 1 to 6, characterized in that the conveying trough (1) is supported on the foundation (9) at least via two supporting struts (3) arranged one behind the other in the longitudinal direction (L).Vibration arrangement according to Claim 6, characterized in that each supporting strut (3) is assigned an imbalance drive (12) or a damping unit (11).Vibration arrangement according to 7 or 8, characterized in that the supporting struts (3) are designed as spring elements (14).Vibration arrangement according to one of Claims 1 to 9, characterized in that the imbalance drives (12) of a damping unit (11) and / or all the imbalance drives (12) of the damping system (10) are designed with the same imbalance.Vibration arrangement according to one of Claims 1 to 9, characterized in that the imbalance drives (12) of the damping system (10) differ from one another at least partially in terms of their imbalance.Vibration arrangement according to one of Claims 1 to 11, characterized in that the imbalance drives (12) of a damping unit (11) have an adjustable phase offset with respect to one another.Vibration arrangement according to Claim 12, characterized in that a control and / or regulating unit is provided for setting the phase offset.Method for operating an oscillating arrangement according to one of Claims 1 to 13, - wherein bulk material is applied to the conveying trough (1) and is set into movement under an oscillating movement of the conveying trough (1), - and wherein the damping system (10) at least partially compensates the dynamic forces generated by the conveying trough (1) by rotating the imbalance drives (12).Method according to claim 14, wherein the bulk material is transported and / or classified along the longitudinal direction (L) as a result of the oscillating movement of the conveying trough (1).Method according to Claim 14 or 15, wherein the imbalance drives (12, 13) rotate at least partially with a phase offset with respect to one another.Method according to claim 16, wherein the damping system (10) is adjusted before and / or during operation by changing the phase offset.

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