From DE 1 103 216 a device for distributing cut tobacco to cigarette-making machines is known, wherein the cut tobacco is fed from a conveyor onto a rotary table from which the tobacco is drawn by stationary sucking pipes spaced at the periphery of a table constituting a distributing element, the cut tobacco fed from the conveyor falling onto a cone located centrally relative to the rotary table. The cut tobacco slides down along the cone onto the rotary table gravitationally and then it is transported due to the centrifugal force as a layer towards the periphery of the table, from where it is sucked by vertical pipes to deliver the cut tobacco to the cigarette-making machines.
DE 198 23 873 presents a similarly operating device for feeding cut tobacco to many machines. The cut tobacco is fed via a vertical channel onto a bowl performing a composed, rotary and circulating, motion. The sucking channels, picking up the cut tobacco from the uniformly formed layer, are arranged vertically within the bowl cover at the bowl periphery.
In GB 959 343 a device is described in which the cut tobacco is fed, as previously, from above onto a rotary distribution disk and is directed by the centrifugal force towards receiving channels arranged radially in the side wall of the distribution chamber.
In a slightly different arrangement, known from DE 300 90 000, cut tobacco is fed through a charging hopper onto a linear vibrational conveyor. The vibrational conveyor transfers the fed cut tobacco to a place above which sucking pipes are situated. The cut tobacco is transported in the form of a layer and the sucking pipes are arranged vertically just above the surface of this layer.
Usually the bottom of the distribution chamber is flat or has the shape of a bowl and it is a surface of revolution and posses a centrally located rotational cone.
The process of feeding the cut tobacco to the cigarette-making machines is discontinuous, the result of which is that the more receiving channels are connected, the more frequent changes of the flow rate of the tobacco through the distributing device will occur. The discontinuity of the feeding process results from the fact that after filling the cut tobacco container located within the machine, the feeding is stopped until the amount of the cut tobacco in the container drops below a certain predefined level, afterwards the feeding is started again. Devices for distributing cut tobacco, employed in the tobacco industry, usually feed a lot of cigarette-making machines. Every change in a total throughput of the receiving channels will result, as a consequence, in a change of the efficiency of the conveyor feeding the distributing device.
All the solutions presented above relate to devices for distributing cut tobacco to cigarette-making machines using gravitational feeding, usually in the form of a feeding channel and a couple of pneumatic receiving channels transferring the cut tobacco to the cigarette-making machines, the receiving channels being connected to the distributing chamber or being located at the periphery of the distributing element for uniform distributing the cut tobacco into the inlets of the receiving channels. For proper operation of all the above devices it is necessary to collect some amount of the cut tobacco in the distribution chamber, which is transferred to the space from which it is received by the receiving channels. During transferring the layer of the cut tobacco gains its optimal thickness in order to ensure repeatable conditions of receiving the cut tobacco by the receiving channels. Therefore the receiving channels are distant from the feeding channel. In each of the devices in the case of temporary stopping the process of feeding the cigarette-making machines, the amount of the cut tobacco, which has been already delivered to the distributing device but has not been yet received, is an excess of the cut tobacco present in the device relative to the amount necessary for its operation. The cut tobacco tends to agglomerate, i.e., to create bundles, the effect of the agglomeration being particularly strong if the cut tobacco is stored in a high layer, as in the vertical channel feeding the distributing device.
If the process of receiving the cut tobacco by the cigarette-making machines, connected to a single distributing device, is stopped, one must stop the conveyor feeding the device, which was operating with a rate adjusted for feeding all the cigarette-making machines. However, due to inertia of the system, the distribution chamber will be filled anyway as well as, partially or fully, then vertical feeding channel. Restarting the device after a longer downtime may occur difficult, since the bulk density of the cut tobacco collected and stored under a pressure within the feeding channel increases and it is significantly more difficult to form a uniform layer of the cut tobacco and to suck the agglomerated tobacco through the receiving channels. Sometimes, in order to restart the feeding system the agglomerated tobacco must be removed from the lower portion of the feeding channel and partially from the distribution chamber.
If a couple of receiving channels will be shut off simultaneously, i.e., in the case of a rapid drop of the received amount of the cut tobacco, an excess of the cut tobacco will arise within the distribution chamber. The efficiency of the conveyor feeding the distributing device will be adjusted to the throughput of the cigarette-making machines that are still working, and the excess of the collected cut tobacco will be used by those machines, however if the excess is relatively large, disturbances in the receiving process may arise.
Frequently, cigarette manufacturers must face the task of producing short series of new cigarette brands. Large distributing devices with rotary tables or vibrational conveyors are expensive and there is no economical justification for using them in the case of frequent changes of the brand of tobacco fed to one or two cigarette-making machines.