EP0515305B1 - Vibrator - Google Patents

Abstract

A vibrator includes a vibrating table; a plurality of driven unbalanced shafts disposed within the vibrating table and arranged in pairs; and a plurality of unbalanced bodies. A separate unbalanced body is connected to each unbalanced shaft. The unbalanced bodies can assume various vibrating frequencies and angular positions. An adjustment device varies the vibrating frequencies and angular positions of the unbalanced bodies relative to one another. Each shaft is driven by a separate motor; the motors are adapted to rotate in synchronism with one another at a predetermined rotational speed. The adjustment device includes an electronic controller for regulating each of the motors. The electronic controller includes an arrangement for changing the vibrating frequencies of the unbalanced bodies by briefly varying a rotational speed of the unbalanced shafts; and an arrangement for changing the angular positions of the unbalanced bodies relative to one another by briefly varying a rotational speed of at least one driven unbalanced shaft of a pair of driven unbalanced shafts.

Description

Technical field:

The invention relates to a vibrating device with a vibrating table, with unbalanced shafts arranged in the vibrating table, assigned to one another in pairs and each having an unbalance body, each of which is individually driven by a motor which rotates at a predetermined speed in synchronization with the other motors, and with one electronic controller as an adjusting device, via which the vibrating frequency and the angular position of the unbalanced bodies can be changed with respect to one another, and each motor can be controlled in an angle-synchronized manner so that the rotational speed of the unbalanced shafts for changing the vibrating frequency and the rotational speed of at least one of the two for changing the angular position of the unbalanced bodies associated unbalanced shafts can be changed briefly.

An adjustable and controllable vibrating device of the type mentioned serves the purpose of optimally compacting concrete elements during their production. This is achieved by program-controlled adaptation of the operating parameters of the vibrating device to the product-specific requirements during the production process.

State of the art:

The following solutions for program control can be found in the prior art: A mechanical adjustment of an unbalance mass from the zero position to a maximum value takes place in the case of external or counter-rotating vibrators by arranging braces which move transversely on the unbalanced shafts and which are connected via an helical connecting rod to an outside the vibrating actuator are connected (DE magazine "Betonwerk + Fertigteil-Technik" issue 10/1988 pp. 48 to 50). A phase adjustment is by means of an electromechanically adjustable superposition gear (DE-A-3 708 922); or possible using a phase adjustment mechanism (DE-C-3 709 112).

An adjustment device for unbalance vibration generators is also known (EP-A-0 092 014), which has the following features: two unbalanced shafts, each assigned to one another and provided with a swing piece, are arranged on a vibrating plate. The vibrating frequency and the angular position of the unbalanced bodies relative to one another can be changed, each unbalanced shaft being driven individually by a drive means. The drive means rotates at a predetermined speed in synchronization with the other drive means. The setting device is a Electronic controller is provided, via which each drive means can be controlled in an angle-synchronized manner so that the rotational speed of the unbalanced shafts can be changed to change the vibrating frequency and the rotational speed of one of the two unbalanced shafts can be changed briefly to change the angular position of the unbalanced bodies.

Presentation of the invention:

• a) Veränderung der Rüttlerfrequenz durch Änderung der Rüttlerwellendrehzahl;
• b) Veränderung der Rüttelkraft zwischen Null und Maximum durch Phasenverstellung von mindestens zwei umlaufenden Unwuchtmassen zueinander;
• c) Veränderung der Schwingungsamplitude durch Kombination der unter a) und b) genannten Maßnahmen.

The invention is based on the following consideration:
Concrete elements are optimally compacted with a vibrating device if the following adjustment and control tasks are carried out:

• a) change of the vibrator frequency by changing the vibrator shaft speed;
• b) changing the vibrating force between zero and maximum by phase adjustment of at least two rotating unbalanced masses to one another;
• c) Change in the vibration amplitude by combining the measures mentioned under a) and b).

Accordingly, the object of the invention is to carry out the adjustment of the operating parameters required for generating the optimal vibrating effect in accordance with a new principle in a vibrating device of the type mentioned at the outset. According to the invention to achieve this object, a vibrating device according to the preamble of claim 1, characterized in that at least four unbalanced shafts are arranged in the vibrating table, each of which is individually driven by one of the motors, that one of the motors as a master drive for the in Depending on the selected speed a fixed one Setpoint specification is provided, and the other motors are provided as slave drives, for which the setpoint is calculated using a PI actuation algorithm from their deviation from the setpoint position.

In the invention, the synchronization of the individual unbalance shafts is achieved by electronic, angularly synchronous control of the unbalance drives. The intensity of the vibrating effect is controlled by an electronic change in the rotor position angle of the individual unbalance drives.

Refinements and developments of the invention are described in the subclaims.

Brief description of the drawings:

Fig. 1

einen Rütteltisch mit vier Unwuchtwellen und Einzelantrieb für jede Welle;

Fig. 2

einen zweiteiligen Rüttteltisch mit acht Unwuchtwellen, von denen je zwei Wellen miteinander gekuppelt sind, und mit Einzelantrieb für jede Welle, wobei auch der Regelkreis für die Einzelantriebe dargestellt ist;

Fig. 3

einen zweiteiligen Rütteltisch mit acht Unwuchtwellen und Einzelantrieb für jede Welle;

Fig. 4

die Wirkungsweise der Phasenverstellung der Unwuchtmassen;

Fig. 5

als Ausschnitt aus Fig. 2 den Regelkreis für einen der Einzelantriebe mit Angabe des Signalflusses.

An embodiment of the invention is shown in the drawing and is described in detail below. They show in the representation with circuit symbols

Fig. 1

a vibrating table with four unbalanced shafts and individual drives for each shaft;

Fig. 2

a two-part vibrating table with eight unbalanced shafts, two of which are coupled to each other, and with individual drives for each shaft, the control circuit for the individual drives also being shown;

Fig. 3

a two-part vibrating table with eight unbalanced shafts and individual drives for each shaft;

Fig. 4

the mode of operation of the phase adjustment of the unbalanced masses;

Fig. 5

2 shows the control loop for one of the individual drives with an indication of the signal flow.

Way of carrying out the invention:

Four unbalanced shafts W1 to W4 arranged in a vibrating table 1 are individually driven by associated motors M1 to M4 via cardan shafts G1 to G4. The unbalanced shafts W1 to W4 are supported in the vibrating table 1 with the aid of roller bearings L1 to L4. A resolver R1 to R4 is mechanically connected to each motor M1 to M4 via a coupling C1 to C4. Couplings are also provided between the shafts of the two-part vibrating table 1 in FIG. 2. Each motor M1 to M4 and each resolver R1 to R4 is electrically connected to a drive converter A1 to A4, which is part of a motor control circuit K1 to K4. A rotor position controller 2 is superordinate to the motor control circuits K1 to K4.

All four motors M1 to M4 rotate continuously at a given speed in absolute synchronism. Imbalance bodies U1 to U4 fastened on the shafts are positioned so that the centrifugal forces cancel each other and there is no vibrating effect - Fig. 4, Fig. 1 -. If vibrations are required, the unbalance bodies U1 to U4 must be phase-adjusted to a value that corresponds to the desired vibrating effect. This is done in such a way that the motors M3 and M4 rotate briefly at a reduced speed compared to the motors M1 and M2, but in synchronism with one another, until the desired phase adjustment is reached - Fig. 4, e.g. 100% in Fig. 3 and 70% in Fig. 2 - in order to then immediately rotate again at the same speed as the motors M1 and M2, so that the set position of the unbalances U1 to U4 is retained for the duration of the vibrating process. The reset to the zero position takes place in the opposite manner. The arrangement shown in Fig. 3 enables the simultaneous operation of the vibrating table halves with different frequencies and vibrating forces.

Each unbalanced shaft W1 to W4 is individually driven by one of the motors M1 to M4. The motor M1 to M4 runs at the specified speed in synchronism with the other motors. An electronic controller is provided as an adjusting device, by means of which the vibrating frequency and the angular position of the unbalance bodies U1 to U4 can be changed. Each motor M1 to M4 can be controlled in an angle-synchronous manner via the electronic controller in such a way that the Vibration frequency, the rotational speed of the unbalanced shafts W1 to W4 and to change the angular position of the unbalanced bodies U1 to U4 relative to one another, the rotational speed of at least one of the two unbalanced shafts W1 to W4 assigned to one another can be changed briefly.

The unbalance bodies U1 to U4 of unbalanced shafts W1 to W4 assigned to one another have an angular position of 180 ° to one another. Via one of the two mutually assigned unbalanced shafts W1 to W4, motors M1 to M4, the one unbalanced shaft is briefly driven at a reduced speed, after reaching the desired new angular position that deviates from 180 °, again at the same speed as the motor driving the assigned unbalanced shaft.

und $\text{cosωt}$

aus dem Resolver R1 bis R4 und Sollwertsignalen aus dem Rotorlageregler 2 über die Betriebsfrequenz f die Drehzahl des Motors M1 bis M4. Dem Rotorlageregler 2 sind aus den Motorregelkreisen K1 bis K4 Istwerte der Rotorlagen der Motoren M1 bis M4 und Betriebsparameter zugeführt. Zu den Betriebsparametern gehören beispielsweise Sollwinkel, Rütteldauer und Stellzeit.The motors M1 to M4 are controlled via the motor control circuits K1 to K4 and the rotor position controller 2. The rotor position control is superior to the motor control circuits K1 to K4. Each motor M1 to M4 is assigned one of the mechanically coupled resolvers R1 to R4 and, as part of one of the motor control circuits K1 to K4, one of the drive inverters A1 to A4. The drive converter A1 to A4 changes depending on output signals $\text{sinωt}$

and $\text{cosωt}$

from the resolver R1 to R4 and setpoint signals from the rotor position controller 2 via the operating frequency f the speed of the motor M1 to M4. Actual values of the rotor positions of the motors M1 to M4 and operating parameters are fed to the rotor position controller 2 from the motor control circuits K1 to K4. The operating parameters include, for example, the desired angle, vibrating time and actuating time.

   mit

Y_n

= Stellgröße für den Zyklus n

X_dn

= Regeldifferenz im Zyklus n

X_{dn - 1}

= Regeldifferenz im Zyklus n - 1

T_A

= Abtastzeit

T_N

= Nachstellzeit

T_V

= Vorhaltezeit

K_p

= Proportionalkonstante.

One of the motors M1 is designed as a master drive, the other motors M2 to M4 are provided as slave drives. Depending on the selected speed, a fixed setpoint is provided for the master drive, and the setpoint for the slave drives is calculated using a PI actuation algorithm from their deviation from the setpoint. The PI positioning algorithm is:

With

Y _n

= Manipulated variable for cycle n

X _dn

= Control difference in cycle n

X _{dn - 1}

= Control difference in cycle n - 1

T _A

= Sampling time

T _N

= Reset time

T _V

= Retention time

K _p

= Proportional constant.

Commercial usability:

The invention can be used commercially in the production of concrete elements that are compacted.

Claims (5)

1. Vibrator comprising a vibrating platform (1) with vibrating shafts (W1 to W4), arranged in pairs and each fitted with an eccentric body (U1 to U4), each shaft being driven by its own motor (M1 to M4), the motors rotating synchronously at a preset speed, and with an electronic regulator as an adjustment device by means of which the vibrating frequency and the angular position of the eccentric bodies (U1 to U4) can be altered relative to each other and in which each motor (M1 to M4) can be regulated at synchronised angles in such a way that, in order to change the vibrating sequences, the rotational speed of the vibrating shafts (W1 to W4) and in order to change the angular position of the eccentric bodies (U1 to U4) to each other, the speed of at least one of the two vibrating shafts (W1 to W4) in each pair can be briefly altered, characterised by the fact that at least four vibrating shafts (W1 to W4) are arranged in the vibrating platform (1) each of which is individually driven by one of the motors (M1 to M4), and by the fact that one of the motors (M1) is provided as main drive for which a fixed setpoint is determined relative to the selected speed, and the remaining motors (M2 to M4) are provided as following drives, for which the preset value is calculated from the deviation from the setpoint position via a PI adjustment algorithm.
2. Vibrating device as in Claim 1 characterised by the fact that the eccentric bodies (U1 to U4) have vibrating shafts (W1 to W4) arranged at an angle of 180° to each other and by the fact that, via the motors (M1 to M4) driving one of the two relatively positioned vibrating shafts (W1 to W4), the one shaft is briefly driven at a reduced speed and, after reaching the new position deviation from 180°, is again driven at a speed that corresponds to that of the shaft allocated to the driving motor.
3. Vibrating device as in Claim 1 or 2 characterised by the fact that the motors (M1 to M4) are regulated by the motor regulating circuits (K1 to K4) and a rotor position regulator (2) arranged above the motor regulating circuits.
4. Vibrating device as in Claim 3 characterised by the fact that each motor (M1 to M4) is allocated a mechanically coupled resolver (R1 to R4) and a drive converter as a component in the motor regulating circuits (K1 to K4) that changes the speed of the motor (M1 to M4) in proportion to the output signal (sin ωt; cos ωt) from the resolver (A1 to A4) and the setpoint signals from the rotor position regulator (2) via the operating frequency (f).
5. Vibrating device as in Claim 4 characterised by the fact that from the motor regulating circuits (K1 to K4), the actual rotor positions of the motors (M1 to M4) and operating parameters are fed to the rotor position regulator (2).

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