1. Field of the Invention
The present invention relates to a system and a method for manufacturing cigarettes, suited for the manufacture of cigarettes of higher hardness.
2. Description of the Related Art
In general, a cigarette manufacturing machine comprises a cut tobacco supply section, a wrapping section, and a cutting section. The wrapping section is supplied with a paper web, which travels in one direction in the wrapping section. The supply section feeds cut tobacco onto the paper web at the starting end of the wrapping section. As the cut tobacco, along with the paper web, passes through the wrapping section, it is wrapped in the web to form a continuous cigarette rod. Thereafter, the formed cigarette rod is delivered from the wrapping section to the cutting section. As it passes through the cutting section, the cigarette rod is cut into individual cigarettes with a predetermined length.
An example of the supply section of a cigarette manufacturing machine is disclosed in Jpn. Pat. Appln. KOKOKU Publication No. 40-14560. This conventional supply section is provided with an endless suction band, that is, a tobacco band as it is called. The tobacco band extends toward the wrapping section, and has one surface formed as a suction surface. Cut tobacco is attracted in a layer to the suction surface of the tobacco band. As the tobacco band travels, the cut tobacco layer is transported toward the wrapping section. The tobacco layer is released from the attraction at the starting end of the wrapping section, whereupon the cut tobacco is continuously fed from the tobacco band onto the paper web at the wrapping section.
As shown in FIG. 1, a cut tobacco layer T.sub.L is formed of individual tobacco shreds K.sub.T which are stacked on a suction surface of a tobacco band 1. Thereafter, the tobacco shred K.sub.T of the layer is fed onto a paper web at the wrapping section.
As the paper web 2, along with the tobacco shreds K.sub.T, passes through the wrapping section, it is first bent in the shape of a U, as shown in FIG. 2. Thereafter, both sides of the U-shaped web 2 are successively bent in a circular arc, whereupon a continuous cigarette rod is formed.
FIG. 3 shows a filter cigarette which is formed of a cigarette obtained by cutting the cigarette rod and a filter connected to the cigarette. FIG. 4 shows an end face of the filter cigarette. In FIGS. 3 and 4, reference numeral 3 denotes a lap portion which combines both side edges of the paper web 2.
As is evident from the foregoing description of the process for forming the cigarette rod, the tobacco shreds K.sub.T on the paper web 2 are kept substantially in layers even though they are wrapped in the web 2. Also, most of the tobacco shreds K.sub.T in the cigarette are oriented in one direction.
More specifically, most of the tobacco shreds K.sub.T are obtained by cutting tobacco leaves. As shown in the exaggerated view of FIG. 5, these tobacco shreds K.sub.T are rectangular fragments each having a pair of long sides K.sub.le with a length L and a pair of short sides K.sub.se with a length S.
Most of these fragments K.sub.T tend to be attracted to the tobacco band 1 with an orientation such that their respective long sides K.sub.le extend along the traveling direction of the tobacco band 1. As shown in FIGS. 1 and 2, therefore, most of the stacked fragments K.sub.T are oriented so that their short sides K.sub.se extend parallel to the cross section of the tobacco band 1 or the paper web 2, and their long sides K.sub.le at right angles to the cross section.
As viewed from the end face of the cigarette shown in FIG. 4, most of the individual tobacco shreds K.sub.T are wrapped in the paper web 2 in a manner such that their short sides K.sub.se extend parallel to the lap portion 3 of the cigarette.
The tobacco shreds K.sub.T more easily undergo elastic deformation when their opposite surfaces K.sub.F (see FIG. 5) are subjected to external forces than when their long and short sides K.sub.le and K.sub.se receive external forces.
Thus, if the cigarette is subjected to external forces in the direction A--A, as shown in FIG. 5, these forces act on the opposite surfaces of most of the tobacco shreds K.sub.T in the cigarette, so that the outer peripheral surface of the cigarette is easily deformed.
If the cigarette is subjected to external forces in the direction B--B, on the other hand, these forces act on the long sides K.sub.le of most of the tobacco shreds K.sub.T in the cigarette, so that the outer peripheral surface of the cigarette cannot be easily deformed.
This hardness characteristic of the cigarette is also indicated by the result of an experiment. More specifically, the hardness of the cigarette is 5% higher in the direction B--B than in the direction A--A.
If the hardness of the cigarette is thus irregular with respect to the circumferential direction thereof, the outer peripheral surface of the cigarette is easily deformed.