Technical data

Principles of Vibration Conveyor Technology – Alignment of the units
7–2
l
The support plate of the drive unit is firmly bolted to the working unit. Toge-
ther they form a continuous mass unit within the resonance system (1).
l
The counterweight is the mass of the housing below. Both masses are con-
nected by leaf springs (3).
l
Rubber feet (6) support the system with respect to its environment.
Smaller drives: each voltage cycle exerts a pulling force on the vibration system.
On a 50Hz supply, the unit will operate with 6,000 vibrations per minute.
Larger drives: For noise protection reasons, every second half cycle is suppressed
(3,000 vibrations per minute at 50 Hz).
By changing the voltage from the controller, the vibration width and hence the
throughput may be adjusted during operation from close to 0 to 100 %. The path
completed during a full vibration cycle, i.e., twice the amplitude, is called the wor-
king vibration width.
7.2 Alignment of the units
7.2.1 Two-body resonance system
Vibration drives are spring-mass resonance systems that exploit the resonance of
the vibration system. If the system is excited, it continues to oscillate with its
eigenfrequency, with a decaying amplitude depending on its attenuation proper-
ties.
If a sinusoidal force acts on this system with a frequency different from the eigen-
frequency (frequency of oscillation or drive frequency), the entire system will no
longer oscillate at eigenfrequency (resonance frequency), but will follow the
rhythm of the force exerted on it (forced oscillation).
The closer eigenfrequency and vibration frequency (drive frequency) are, the lar-
ger the vibration width. However, for magnetic vibration drives, operation in the
immediate vicinity of the resonance frequency is not feasible:
l
Changes in the attenuation that are caused by different properties of the
transported material lead to significant variations in vibration width.
l Exploiting large vibration widths close to resonance requires a wide air gap.
As the magnetic attraction is inversely proportional to the square of the width
of the air gap, the driving force does not remain constant.
Furthermore, for a stable operation of the resonant system, a well-defined
distance from the resonance frequency is required. In this case, the eigenfre-
quency may be lower or higher than the drive frequency.
7.2.2 Implementation in practice
In practice, the tuning may be accomplished by changing the working weight
(adding plates for additional weight):