22 May, 2009
What is a vibratory bowl feeder, its uses and working?
Vibrations have fascinated human beings since a very long time. Virbatory Bowl Feeders are around since the early part of the Twenthieth Century. No major alternative to a Vibratory Bowl Feeder has been invented in the meantime. Rotary Feeder which uses a motorised drive is a very poor cousin of the Vibratory Bowl Feeder. (We will discuss the advantages / disadvantages of using a Rotary Feeder vis a vis Vibratory Feeder in another write up).
What are Vibratory Bowl Feeders used for?
Vibratory bowl feeders are commonly used for aligning and feeding of small parts. They are the very versatile and widely used for feeding of parts in an automatic assembly.
What is a Vibratory Bowl Feeder? And how does it work?
Vibratory Bowl Feeders are used for feeding of components to various Machines. The actuation / Vibrations take place by electromagnets. The Vibratory Bowl Feeder is a device that converts Electro-magnetically produced vibrations into mechanical vibrations. These mechanical vibrations are utilised for movement of the workpiece along the track of the Bowl Feeder.
Magnetic coil, which is fixed to the counter mass is energised with supply of electric current, producing a force, which in turn attracts and releases the magnet armature. As the magnet is rigidly fixed to the top spring holder and bowl feeder, the vibrations are transferred to the spiral-conveying track of the bowl. Depending on the angle of gradient of the leaf springs and lead angle of the helix of conveying track, the workpieces move with every vibration above the track in small jumps.
During one period of 50 cycle AC mains the magnet attains its maximum attraction twice since the magnetic force is not dependent on the direction of current flow. Thus the magnet produces a vibrating frequency of 100 cycles, which is necessary for smooth & reliable movement of small & light weight workpieces. Some Bowl Feeder manufacturers use 50 Cycles / HALF WAVE Bowl Feeders too. The biggest advantage of a 100 cycle / FULL WAVE Vibratory Feeder is that it consumes almost 40% less energy as compared to a HALF WAVE Vibratory Feeder. Secondly, as the vibrations are smooth and reliable, the parts being fed do not get damaged, which is a possibility in case of HALF WAVE bowl feeders.
Thus a vibratory bowl feeder consists of a bowl mounted on a base by three or four inclined leaf springs or packs of springs. The springs constrain the bowl so that, as it travels vertically. As the components move up an inclined track along the edge of the bowl, the tooling in the bowl orients the components into the required orientation or rejects the misaligned parts into the center of the bowl where they begin their travel up the track again. One to six electromagnets, mounted on the lower counter weight / heavy base, generates the force to drive the bowl feeder. The Counter weight rests on rubber feet, which serve to isolate the vibration of the Vibratory feeder.
The components are conveyed in the bowl by one of two modes: sliding or hopping. In the sliding mode, motion is produced from friction between the part and the bowl. As the bowl rises and turns, the friction between the track and the part pushes the part forward with the track. When the track descends and turns backward, the force of friction is smaller and the part slides forward relative to the bowl. In the hopping mode, the part moves forward with the bowl as it rises and turns, but it experiences freefall when the bowl’s downward acceleration exceeds the acceleration of gravity. During free-fall, forward motion is created as the bowl moves backward relative to the part.