Do you need extremely accurate dosing when filling a large number of packs, bags or boxes in a specific cycle time? In which case, mechanical coarse-fine dosing is an excellent option. Coarse dosing delivers the required high capacity. Once the required quantity is about to be reached, fine dosing delivers the accurately measured, precise dosing. Optional retractable screws make it easy to meet strict hygiene requirements.
Custom-made double dosing screw conveyors are available from Van Beek. Every double dosing screw conveyor we supply is based on the same principle. For fast coarse dosing, the large and small screws rotate. When the required weight has almost been reached, the large screw stops. The refill valve closes. The fine dosing screw then tops up the content to precisely the required pack weight. Next, the refill valve of the fine dosing closes.
Coarse dosing is performed by the large dosing screw. For flour or other fine powders, a agitator creates activation, in other words, an efficient product flow. The rotation speed determines the speed at which the screw rotates, and how much product is dosed. Hence the name volumetric dosing. The setpoint specifies the quantity per pack or box. For example, for a 20 kg pack, this can be 19 kg. The large screw stops when this set weight is reached. A refill valve then shuts off the screw. As a result, no more product can flow out. The small dosing screw then tops up the pack. This process usually takes only a matter of seconds.
The small screw is used to accurately top up the final amount into the pack. After the required weight has been reached, e.g. 20 kg, the screw will stop and the pneumatically operated refill valve closes. In combination with the large dosing screw, you can quickly and accurately fill packs mechanically.