Vibratory bowl feeder
Vibratory feeder (often shortened to bowl feeders ) are vibratory conveyors for vertical promotion . Powdery to coarse-grained bulk goods as well as lumpy goods are conveyed . In addition to transport, they are often used to sort small parts in bulk (e.g. screws, electronic components) or to make them available in the correct position for automatic further processing.
functionality
The basic functionality of a vibratory bowl feeder corresponds to that of all vibratory feeders . The conveyor element, here the spiral track, is set in vibration by means of an electromagnetic oscillating drive. As a result, the product lying on top is thrown in the conveying direction in small throwing movements, the micro throw, and thus moved or transported.
The oscillation is generated by the magnetic field of a coil ( electromagnet operated with alternating current ). The amplitude and the oscillation frequency and thus the conveyor speed can be set by a control device. The body vibrates around its center. In the small vibratory motion in the conveying direction (with or counterclockwise, depending on type) is determined by the mechanical structure of the conveyor, depending on the throw code performs an upward movement ( micro-litter ). The items to be sorted are thus moved along with them. During the vibration movement against the conveying direction, there is a small downward movement and the material to be sorted has little or no mechanical contact with the path of the vibratory conveyor. Due to the inertia of the material to be sorted, it remains and is moved a little further to the outlet by the next vibration movement in the conveying direction (micro-throwing principle). The amplitude of the vibration movement is limited by the air gap of the magnet and depends on the size.
Electromagnetic vibratory drives are available in sizes from approx. 60 mm to 1000 mm (drive or seat diameter).
For smaller devices with a drive diameter of up to 400 mm, an oscillation frequency of 100 Hz (full-wave operation) is usually used. The air gap is usually between 0.1 and 1.2 mm. This oscillation frequency of 100 Hz is used to achieve smooth and gentle conveying of smaller or lighter workpieces.
An oscillation frequency of 50 Hz ( half-wave operation ) is used for devices with sizes from around 500 mm and up to 1000 mm drive diameter . In this case, the air gap can be up to 3.5 mm and more.
The spiral conveyors work most efficiently when they are excited precisely with the mechanical resonance frequency resulting from the structure . Often this is only a few Hertz below or above the nominal frequency. The resonance frequency changes depending on the load of the material being conveyed. Some frequency regulators specially developed for this purpose ("fully automatic frequency regulators") can automatically readjust this frequency change in order to produce constant vibrations.
The conveying effect and wear can be influenced by various materials and coatings. (e.g. plastic coatings of the steel body). The use of special conveyor brush covers has proven effective for oily conveyed goods.
The sorting tops of vibratory spiral conveyors have the shape of a pot with a firmly connected helical conveyor track ( spiral ), which is often widened towards the top. A distinction is made between cone shape, step shape and cylinder shape. Each vibrating bowl can only convey one sorting product of a certain size and mass. By exchanging components, similar products can be sorted and conveyed, but never different products at the same time. The body is usually prefabricated by machine. The adjustments (tracks, harassment) are usually done by hand. Most vibratory bowl feeders are therefore unique pieces.
With additional sorting elements (so-called "baffles"), the items to be sorted are oriented in the correct position and can thus be further processed. Parts that are not in the correct position and cannot be rotated get back into the pot through further baffles.
use
- They are mostly used in industry to gently transport bulk goods from bottom to top.
- Since the helical arrangement of the conveyor track results in a long, effective conveyor route, the bulk material remains on the conveyor track for a relatively long time. If the product is fed in hot, it cools down during this dwell time on the conveyor belt, usually without having to use additional cooling units. Appropriate technical designs can also be used to cool with water or air. One then speaks of a spiral cooler, vibrating spiral cooler or cooling spiral conveyor. If, on the other hand, there is additional heating (e.g. with water or thermal oil), it is referred to as a heating coil conveyor.
- In smaller sizes, the spiral conveyor is mostly used for sorting screws, turned parts, electronic parts, etc. This function is achieved by installing various sorting elements (so-called baffles). The items to be sorted are then oriented in the correct position and fed to a further work process.
Other names
In practice there are various other names for bowl feeders. These each emphasize certain aspects of the bowl feeder or its application and partially delete information about other aspects. They are therefore imprecise and, in actual use, are only fully determined from the technical context and are therefore problematic.
For a spiral conveyor with the main purpose of transporting parts, the term "parts conveyor" can also be used in general (neglecting the functional principle) in accordance with its purpose. However, this general term also applies to linear conveyors and the like. a. to.
Under the aspect of the pot shape and the conveying task, the term "pot conveyor" occurs, which excludes other designs (such as the linear conveyor). The term does not provide any information about whether sorting takes place at the same time during the transport process. If necessary, it must be determined separately whether such a double application exists.
For a spiral conveyor used to sort parts, the term "automatic sorting machine" can also be used. Since such a spiral conveyor usually has the shape and size of a pot, the term "sorting pot" is also used for it.
Under the aspect of the vibrating movement in connection with the shape of the pot, the term "vibrating pot" (which neglects all other aspects) is also used. A vibrating bowl could also have a purpose other than sorting parts (deleting the information as to whether sorting should actually be carried out or something else).