SIEBTECHNIK banana screening machines are freely vibrating machines, that is, their vibrating circle diameter freely adjusts to suit the mass ratio of screen box and unbalance mass. Banana screening machines are designed to enable selection of a steep (approx. 75°) or shallow throw angle (approx. 40°). This flexibility enables different screen panel tilt angles, from steeply downwards (approx. 40°) through horizontal to gently upwards (approx. 5°) to be achieved on a single screening machine. Examples are combined classifying and dewatering screens in the salt industry (thin-layer screening followed by dewatering).
Their operational behaviour makes SIEBTECHNIK banana screening machines high-speed screens. The steep screen-panel tilt enables a high transport speed to be reached.
A very thin layer forms, with most of the fine material being separated out through the long mesh holes. The screen tilt decreases in the middle and discharge sections, resulting in a reduced transport speed. In these sections excellent near-mesh-sized grain screening is achieved.
For example, the screen panel in the steep section can be tilted downwards at 25° to 40°, in the middle section at 15° to 25° and in the shallow section at 0° to 15° or upwards at + 5°. The number of tilt stages and their angles can be fixed individually, as required (e.g. in the case of restrictions because of existing steel designs).
Our BHG (double unbalance gear unit), BV (circular-motion screen) and BHR (unbalance motor) series screening machines offer separation sizes of 0.5 to 150 mm and a screen area of between approx. 1 and approx. 40 m². The machines can be set up for a vibration amplitude of 2 – 14 mm, depending on the product to be processed. The screen set-up can comprise between one and two screen decks.
Speed and vibration amplitude on the banana screening machine can be varied to suit the product and so ensure a lastingly perfect screening outcome.
The screen box is optionally set up to hold screen panels tensioned lengthways or for level screen decks and naturally also for system screen cloths by different screen cloth manufacturers.
The screen box, which consists of side walls and cross-members, can withstand all static and dynamic forces. On the circular-motion variant the vibration generating system is arranged at the centre of gravity. On double unbalance gear units or unbalance motors, however, it is not arranged at the screen box’s centre of gravity but mounted on a drive bridge. The important thing is that the resulting force direction runs through the centre of gravity.
The banana screening machine is driven by a V-belt drive with intermediate transmission or by a direct drive through a universal joint shaft. Double unbalance gear units have an oil filling. Unbalance motors are grease-lubricated for life. Circular-motion screens are optionally oil- or grease-lubricated.
The screen box is supported elastically against the substructure on 4 spring elements. Here various systems of spiral compression springs, rubber buffers, vibration elements or air bellows are possible and, if necessary, combinable (hybrid suspension).
For dusty screening material we can, if required, supply linear-vibrating screening machines with a dust cover or an enclosed dustproof box. Also available are individually adaptable screening aids in the form of beating devices or spraying systems.
The robust construction using and combining standard component parts ensures high flexibility and customer-focused solutions, on the one hand, and, on the other, enables the construction of machines with low-maintenance running time and a long service life.