The complete electromagnet consists of the core bearing the winding and the corresponding armature (I Piece). The electromagnet, the armature and the leaf springs form the drive system of the vibratory feeder. The weight differential between the resting mass, the oscillating mass and the spring force result in a resonant vibration system. Vibratory feeders can therefore only work in a relatively small frequency range around the resonance point. All components of the entire drive system must be adjusted to this frequency. It is therefore important that the electromagnet is constructed for the correct frequency otherwise the total power of the magnet cannot be utilised or it could become overheated due to increased losses. Due to conventional control systems, most vibratory feeders work with the same or double vibration frequency of the connection power. 50 Hz or 100.
Low frequency vibration systems
Low frequency systems with vibration frequencies of approximately 15 Hz and 25 Hz are used for particular applications (bulk conveying or product with special feeding characteristics); these systems must be operated with special frequency converters (REOVIB MFS).
In addition to the frequency specification in Hz, also the terms “full wave” (6000 vibrations/ minute) or “half-wave” (3000 vibrations/minute) have become customary for specificationof the vibration frequency. The terms “full wave” and “half-wave” are derived from the sinusoidal wave of the power frequency:
- With half-wave = 50 Hz (60 Hz) a sinusoidal half-wave isblocked by a diode or a triac
- With a full wave = 50 Hz (60 Hz) the positive and negativehalf-waves each produce vibration
- 33000 vibrations/min = 50 Hz (50 x 60 sec), or
- 6000 vibrations/min = 50 Hz (100 x 60 sec) are comparable with the specification of revolutions per minute (rpm) for a motor
It is important that the mechanical vibration frequency of the feeder system, the air gap as well as the type of drive control (output voltage and output frequency) are considered in the electrical design of the electromagnets.