Vibrating conveyor

Abstract

For tuning a vibrating conveyor with an electric vibrator unit (4) driving a vibrating element (5) connected with a conveying unit (3) of the vibrating conveyor (1) so that the conveying unit (3) is oscillated to a mechanical resonance frequency f R of the vibrating conveyor (1), it is provided that the electric drive unit (10) changes the frequency f V of the alternating drive voltage (u V ) in a given frequency range, that the current consumption of the electric vibrator unit (4) is measured at different applied frequencies f V of the alternating drive voltage (u V ) and that the electric drive unit (10) uses the frequency f V with the lowest current consumption of the electric vibrator unit (4) as the frequency f V of the alternating drive voltage (u V ) to operate the vibrating conveyor (1).

Description

TECHNICAL FIELD

[0001] The invention relates to a vibrating conveyor having an electric vibrator unit driving a vibrating element, which is connected to a conveying unit of the vibrating conveyor to oscillate the conveying unit; and further having an electric drive unit supplying an alternating drive voltage with a frequency f V to the electric vibrator unit to oscillate the conveying unit, wherein the frequency f V of the alternating (AC) drive voltage is tuned to a mechanical resonance frequency f R of the vibrating conveyor. The invention further relates to a method of operating such a vibrating conveyor. BACKGROUND

[0002] Conveyor systems are commonly used machines in production, handling or assembly plants for moving articles from one location to another. Conveyor systems are often used in many industries for conveying a wide variety of parts and materials. For conveying bulk materials, often vibrating conveyors are used.

[0003] Vibrating conveyors are machines having a solid conveying unit, which is linearly or rotationally oscillated. The articles to be conveyed are placed on the oscillating unit and follow the oscillating movement of the conveying unit. The oscillating conveying unit is driven by at least one electromagnetic vibrator, which is connected to the conveying unit and transmits the oscillating movement of the vibrating element of the vibrator to the conveying unit. To support the oscillation, also at least one spring can be connected to the conveying unit.

[0004] Different embodiments of electromagnetic vibrators are conceivable. The vibrator can be designed as an electric coil with a core or as a magnetic element as vibrating element, which moves in response to an electromagnetic field generated by the coil. When an oscillating voltage, for example a sinusoidal voltage with a certain frequency, is applied to the coil, the vibrating element oscillates with the same frequency.

[0005] Furthermore, piezoelectric actuators, in particular amplified piezoelectric actuators, can be used as vibrators. Applying a voltage to a piezoelectric actuator causes a stroke of the piezoelectric element. An amplified piezoelectric actuator usually amplifies the very small movement (elongation) of the piezoelectric element to a larger movement by means of a mechanical transmission. In this way, the stroke of the piezoelectric element is converted into a larger stroke. The stroke of the amplified piezoelectric actuator then follows the stroke of the piezoelectric element. Such piezoelectric actuators are sufficiently well known and are available in various embodiments.

[0006] Furthermore, other types of electromagnetic vibrators are possible. All electromagnetic actuators have in common that an oscillating voltage or current applied as power supply to the vibrator is converted into a vibrating movement of the vibrating element of the vibrator. Usually, but not necessarily, the frequency of the vibrating element corresponds to the frequency of the oscillating supply voltage or current.

[0007] Operating the vibrator at or near the mechanical resonant frequency of the oscillating system, i.e., the vibrating element and the vibrating conveyor unit, is advantageous, thereby achieving a large oscillation amplitude with minimal energy supplied by the power source and with small movements of the vibrating element. For this purpose, the frequency of the vibrating element (driving the oscillation) must match or be close to the resonant frequency of the oscillating system.

[0008] To excite a vibratory conveyor with its mechanical resonant frequency, the vibrator can be mechanically tuned to a specific frequency, or the drive system can be adapted to the mechanical resonant frequency.

[0009] A given power grid, such as a 50 Hz or 60 Hz AC mains power supply, can be used as the power supply for the vibrator. In such an implementation, the frequency originates from the power grid, and the amplitude of the vibration can be controlled by adjusting the amplitude of the supply voltage, for example, using phase shift control. For resonance, the mechanical resonant frequency must be tuned to the excitation frequency (the frequency derived from the supply voltage). This is typically done manually using a mechanical regulator in the oscillation system, for example, by changing the mechanical stiffness (damping) or spring characteristics. However, this is inconvenient and requires a trained operator. Furthermore, the mechanical resonant frequency usually changes during the operation of the vibratory conveyor. The mechanical resonant frequency depends on the conveyed items (size, weight, shape), the quality of the items on the conveyor surface (fill level, number of items), mechanical wear, etc. Therefore, permanent manual adjustment of the mechanical resonant frequency is required to optimally operate the vibratory conveyor over time.

[0010] To avoid manually adjusting the mechanical resonant frequency, controlled electromagnetic vibrators have been proposed. These vibrators allow for changes in the frequency of the supplied voltage or current, thereby altering the frequency of the vibrating element. Therefore, it is possible to match the frequency of the vibrating element to the changing mechanical resonant frequency of the oscillating system. Such controlled electromagnetic vibrators are known from WO 2018 / 069819 A1. In WO 2018 / 069819 A1, the phase difference between the oscillation of the conveying surface and the supplied voltage is used to control the frequency of the supplied voltage. Resonance is achieved when the phase difference is zero. An accelerometer is used to detect the oscillation of the conveying surface. This means that an additional accelerometer is required on the vibrating conveyor. The sensor output is processed in the control unit according to a specific control algorithm. Therefore, the vibrating conveyor must be equipped with special electronics with an interface to cover the control unit (e.g., for controlling the throughput or conveying rate of the vibrating conveyor), and machine manufacturers wanting to use vibrating conveyors in their machines rely on vibrator manufacturers because the special electronics must be integrated into the machine control. Summary of the Invention

[0011] Therefore, the object of the present invention is to provide a vibratory conveyor that can be used more flexibly and more easily.

[0012] This objective is achieved through the features of the independent claims. By automatically (discretely or analog) scanning to identify the natural resonant frequencies of the vibratory conveyor and its oscillating mechanical components, operation of the vibratory conveyor can be achieved by exciting it at its mechanical resonant frequencies. The complete technology can be embedded in an electric drive unit that can be used with various vibratory conveyors. External special electronics or sensors are no longer required. Machine manufacturers are no longer dependent on the manufacturers of the vibratory conveyors.

[0013] To tune the vibratory conveyor to the drift resonant frequency, the system can be easily retuned periodically or as needed. Retuning can be achieved by repeatedly performing frequency scans and measuring current consumption. The frequency of the supply voltage can also be changed by a given frequency increment. Attached Figure Description

[0014] In the following text, see references Figures 1 to 4 To describe the invention in more detail, Figures 1 to 4 An illustrative and non-limiting advantageous embodiment of the invention is shown by way of example. In the accompanying drawings:

[0015] Figure 1 and Figure 2 A possible embodiment of a vibrating conveyor is shown.

[0016] Figure 3 An amplified piezoelectric actuator as a vibrator is shown, and

[0017] Figure 4 An embodiment of the electric drive unit is shown. Detailed Implementation

[0018] Figure 1 and Figure 2 An exemplary embodiment of the vibrating conveyor 1 is shown, in Figure 1 The middle one is a linear vibrating conveyor, in Figure 2 The present invention is a rotary vibrating conveyor. However, the direction of the oscillation (indicated by the double arrows) is irrelevant to the present invention. The vibrating conveyor 1 includes a vibrator 2, which is connected to and drives a conveying unit 3. Goods 6 to be conveyed are arranged on the conveying unit 3, for example, as shown in the figure, bulk materials are arranged. The goods 6 are conveyed by the oscillating motion of the vibrating conveyor 3.

[0019] At least one spring 7 connected to the conveying unit 3 may also be provided to support the oscillating motion of the conveying unit 3.

[0020] The vibrator 2 includes an electric vibrator unit 4 and a vibrating element 5 that interacts with the vibrator unit 4. The vibrating element 5 is typically mechanically connected to the conveying unit 3 of the vibrating conveyor 1. When an AC drive voltage u is supplied... V At this time, the electric vibrator unit 4 causes the vibrating element 5 to oscillate. Due to the connection between the vibrating element 5 and the conveying unit 3, this oscillation is also applied to the conveying unit 3. The electric vibrator unit 4 can have different embodiments.

[0021] In an advantageous embodiment, the electric vibrator unit 4 is an electromagnetic coil, and the vibrating element 5 is a magnetic element, such as... Figure 1 and Figure 2 As shown. The magnetic element can be made of any magnetic material, such as ferromagnetic material, or, for example, the magnetic element can also be the magnet itself, such as a permanent magnet or an electromagnet. The magnetic element 5 interacts with the electromagnetic field generated by the electromagnetic coil 4 and moves in response to the electromagnetic field. The vibrating element 5 can also be designed as the moving core of the electromagnetic coil (e.g., Figure 2 (As shown). When an AC drive voltage u is supplied to the electromagnetic coil... V At that time, the vibrating element 5 oscillates in response to the electromagnetic field. The oscillation frequency of the vibrating element 5 is related to the AC driving voltage u. V The frequency corresponds to this. Therefore, the AC drive voltage u can be changed. V The frequency of the vibration element 5 is adjusted by adjusting the frequency of the vibration.

[0022] In another advantageous embodiment, the vibrator 2 is a piezoelectric actuator, preferably an amplified piezoelectric actuator 9. An alternating current driving voltage u is applied to the piezoelectric actuator. V The oscillating stroke of the piezoelectric element that causes the piezoelectric actuator. The piezoelectric actuator 9 typically amplifies the very small movement (elongation) of the piezoelectric element 15 into a larger movement by means of a mechanical transmission device 16. Figure 3 An amplified piezoelectric actuator 9 is schematically shown. In this embodiment, a mechanical transmission device 16 serves as a vibrating element 5, which is connected to the conveying unit 3 of the vibrating conveyor 1, and a piezoelectric element 15 serves as an electric vibrator unit 4. The oscillation of the piezoelectric element 15 is related to the AC drive voltage u. V This corresponds to the frequency. This can be related to the AC drive voltage u. V The frequencies are the same as or have a fixed relationship with each other. Therefore, the AC drive voltage u can be changed. V The frequency of the vibration element 5 is adjusted by adjusting the frequency of the vibration.

[0023] Typically, the oscillation frequency f of the vibrating element 5 O With AC drive voltage u V frequency f V Correspondingly. This could be related to the AC drive voltage u. V frequency fV The same frequency or frequencies with a fixed relationship. Therefore, it can be achieved by changing the AC drive voltage u. V frequency f V To adjust the oscillation frequency f of the vibrating element 5 O So that the oscillation frequency f of the vibrating element 5 is made O The mechanical resonance frequency f with vibrating conveyor 1 R Matching. The mechanical resonant frequency f of vibrating conveyor 1. R Defined by the oscillating components of the vibrating conveyor 1, namely, the vibrating element 5, the conveying unit 3 (loaded with articles), (one or more) springs 7 (if present), and possibly other oscillating components of the vibrating conveyor 1.

[0024] A controllable electric drive unit 10 is provided, which generates a motor with a controllable frequency f. V AC drive voltage u V Typically, the AC drive voltage u V The amplitude can also be controlled by the electric drive unit 10. The electric drive unit 10 can be implemented as a controlled power converter, for example, as a frequency converter when the electric drive unit 10 is connected to the AC power grid 11, or as an inverter when it is connected to the DC power grid 11.

[0025] like Figure 4 As shown, the electric drive unit 10 includes a power electronic device unit 12, which converts the supply voltage u from the power grid 11 into voltage. S (AC or DC) converted to a frequency of f V The required AC drive voltage u V The power electronic device unit 12 is typically an analog circuit comprising multiple semiconductor switches, usually arranged in multiple half-bridge circuits. The power electronic device unit 12 is controlled by the control unit 13, causing the power electronic device unit 12 to generate a frequency f. V and / or the amplitude of the AC drive voltage u V .

[0026] The purpose of vibrator 2 is to utilize its mechanical resonant frequency f R Or close to its mechanical resonant frequency f R This is to excite the vibrating conveyor 1, or more precisely, the oscillation system having the oscillating component of the vibrating conveyor 1, thereby maximizing the oscillation amplitude of the conveying unit 3. For this purpose, the oscillation frequency f of the vibrating element 5 is... O It must be tuned to the mechanical resonant frequency f of the vibrating conveyor 1. R However, the mechanical resonant frequency f of the vibrating conveyor 1 RIt is usually unknown and may drift over time. Drift may be caused by mechanical wear in the mechanical parts of the vibrating conveyor, load changes (mass changes) of the conveying unit 3, temperature changes, etc.

[0027] In order to achieve the oscillation frequency f of the vibrating element 5 O Tuning to the mechanical resonant frequency f of vibrating conveyor 1 R A current measurement sensor 14 is provided, for example, in such a case... Figure 4 In the electric drive unit 10 shown, the current measuring sensor 14 measures the AC drive current i supplied to the electric vibrator unit 4. V The current consumption of the electric vibrator unit 4 was measured accordingly. This was done to determine the mechanical resonant frequency f. R AC drive voltage u V The frequency f changes, for example, by scanning a certain frequency range (discrete or analog), and the current consumption is measured in this way. This can be done by the control unit 13. The AC drive voltage u that causes the lowest current consumption. V frequency f V That is, the AC drive current i that causes the measurement V The lowest frequency, and the mechanical resonance frequency f R Correspondingly, when the oscillation frequency of the vibrating element 5 is related to the AC drive voltage u... V frequency f V When they are the same, then the frequency f V It is equal to the mechanical resonance frequency f R If the oscillation frequency of the vibrating element 5 is related to the AC drive voltage u... V frequency f V If there is a fixed relationship, then the mechanical resonant frequency f can be determined using the known relationship. R However, it is usually not necessary to know the mechanical resonant frequency f. R The value of f is required. All that is needed is to supply the vibrator unit 4 of vibrator 2 with a frequency f. V AC drive voltage u V This ensures that the vibrating conveyor 1 operates at its mechanical resonant frequency f. R Motivated.

[0028] AC drive voltage u V frequency f V For example, the oscillation can be tuned to resonance by changing a range within a control unit 13; this range can be preset or settable. Frequency f V It can vary in sufficiently small increments, such as 0.5 Hz or 1 Hz, or even smaller increments, or it can vary continuously. For example, for a known mechanical resonant frequency f... RFor a 100 Hz vibrating conveyor 1, a frequency scan can be set, for example, between 95 Hz and 105 Hz.

[0029] In order to tune the vibratory conveyor 1 to resonance, the control unit 13 can generate pulses with different frequencies f to supply the electric vibrator unit 4. V AC drive voltage u V These AC drive voltages u are measured using current measurement sensor 14. V Each of them has an alternating current i V Current consumption in the form of [formula missing]. Control unit 13 collects and measures the AC drive current i. V The measured AC drive current i V The lowest value corresponds to the frequency f V Used to drive the electric vibrator unit 4.

[0030] The control unit 13 can be designed as microprocessor-based hardware that runs certain software installed on the hardware (to implement tuning and control functions). However, the control unit 13 can also be implemented as a programmable logic controller (PLC) or an integrated circuit (IC), such as an application-specific integrated circuit (ASIC) or a field-programmable gate array (FPGA). Furthermore, it can be conceived as an analog circuit or analog computer implementation. Combinations of such hardware devices and circuits are also possible.

[0031] AC drive voltage u V or its frequency f V More precisely tuned to the actual mechanical resonant frequency f of the vibrating conveyor 1 R This can be repeated periodically or as needed to adjust to the mechanical resonant frequency f. R Possible drift. This can be done completely automatically, without the need for any trained personnel.

[0032] AC drive voltage u V The amplitude can be preset or set during the setting process of the vibrating conveyor 1, or it can be changed when needed.

[0033] The mechanical resonant frequency f can be detected by monitoring the current consumption of the electric vibrator unit 4. R The drift. When the actual AC drive current i is measured. V When the deviation from the known or given expected current (which may be the current with the lowest value in the tuning step) becomes large, the AC drive voltage u of the vibratory conveyor 1 can be required. V frequency f VRetuning is then performed. This can be done by setting or specifying an allowable current difference, and retuning occurs when the deviation exceeds this specified allowable current difference. For retuning, the process described above for finding the resonant frequency f can be repeated. V The steps are as follows. To readjust the resonant vibrating conveyor 1, the frequency f can also be slightly adjusted. V For example, by using a given frequency increment, one can better approach the resonant frequency f. R For smaller deviations, the frequency f can be adjusted in a given frequency increment. V For larger deviations, retuning can be requested. The values ​​for these “small” and / or “large” deviations can be preset in the control unit 13, or they can be set before operation begins or during operation of the vibrating conveyor 1.

Claims

1. A method for controlling the oscillation of a vibrating conveyor (1), the vibrating conveyor having an electric vibrator unit (4) that drives a vibrating element (5) connected to an oscillating conveying unit (3) of the vibrating conveyor (1), wherein a frequency f is supplied to the electric vibrator unit (4). V AC drive voltage (u) V ), and the AC drive voltage (u V The frequency f V Tuned to the mechanical resonant frequency f of the vibrating conveyor (1) R Its characteristics are, In order to convert the AC drive voltage (u) V The frequency f V Tuned to the mechanical resonant frequency f of the vibrating conveyor (1) R , so that the AC drive voltage (u) V The frequency f V The frequency varies within a given range, and the electric vibrator unit (4) is measured at the AC drive voltage (u). V Different application frequencies f V The current consumption below, and wherein the frequency f with the lowest current consumption of the electric vibrator unit (4) is... V Used as the AC drive voltage (u) V The frequency f V To operate the vibratory conveyor (1).

2. The method of claim 1, wherein, The alternating driving voltage (u V ) has a frequency f V which varies in increments of a given frequency.

3. The method according to claim 1 or 2, characterized in that, periodically or when a deviation of the actual alternating current drive current (i C ) from a given desired current flow exceeds a given permissible current difference, a retuning of the frequency f V of the alternating current drive voltage (u V ) is initiated.

4. The method of claim 3, wherein, For retuning, the steps of claim 1 are repeated.

5. The method of claim 3, wherein, For retuning, the frequency f V of the alternating driving voltage (u V ) is varied in given frequency increments.

6. A vibrating conveyor with an electric vibrator unit (4) driving a vibrating element (5) which is connected to a conveying unit (3) of the vibrating conveyor (1) to oscillate the conveying unit (3) and with an electric drive unit (10) supplying the electric vibrator unit (4) with an alternating drive voltage (u(t)) having a frequency f(t) to cause the conveying unit (3) to oscillate, wherein the frequency f(t) of the alternating drive voltage (u(t)) is tuned to a mechanical resonance frequency f of the vibrating conveyor (1), characterized in that V the electric drive unit (10) is designed to supply the electric vibrator unit (4) with the alternating drive voltage (u(t)) having a frequency f(t) which is tuned to the mechanical resonance frequency f of the vibrating conveyor (1) and which is variable in a range of 0 < f < f V . V V R The electric drive unit (10) changes the AC drive voltage (u) within a given frequency range. V The frequency f V The current measurement sensor (14) is provided to measure the AC drive voltage (u) V Different application frequencies f V The current consumption of the electric vibrator unit (4) is described below, and the electric drive unit (10) will have the lowest current consumption frequency f of the electric vibrator unit (4). V As the AC drive voltage (u V The frequency f V , used to operate the vibrating conveyor (1). ​​​ 7. The vibratory conveyor of claim 6, wherein, An electric coil is provided as an electric vibrator unit (4).

8. The vibratory conveyor of claim 7, wherein, A moving core of the electric coil or a magnetic element interacting with the coil is provided as a vibration element (5).

9. The vibratory conveyor of claim 6, wherein, An amplifying piezoelectric actuator (9) with a piezoelectric element (15) and a mechanical transmission (16) is provided, the mechanical transmission (16) serving as a vibration element (5) and the piezoelectric element (15) serving as the electric vibrator unit (4).

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