System for controlling lamina size in raw material treatment process for tobacco leaves

A system for controlling the lamina size in a raw material treatment process for tobacco leaves comprising measuring means for measuring the production rate of the laminae larger than a given size in the raw material treatment process in which the tobacco leaves which have been provided with a water content and temperature by a humidity controller are stripped into laminae and ribs by means of rib removing machines capable of changing a mechanical impact force applied upon the tobacco leaves by changing the rotational number of grid or threshing gear and are then separated by means of separating machines, and operational control means for receiving measurement signals from said measuring means as a feedback signal for searching a water content, temperature and rotational number of grid or threshing gear which minimize the production rate of the laminae not larger than a given size by a hill-climb method using the water content and temperature provided by the humidity controller and the rotational number of grid or threshing gear as manipulation factors.

BACKGROUND OF THE INVENTION 
The present invention relates to a system for controlling the lamina size 
in a raw material treatment process for tobacco leaves. 
In general tobacco production process, tobacco leaves raw materials are 
separated each other and then are provided with a flexibility by the 
addition of water and steam from a humidity controller. Thereafter they 
are stripped into parenchyma (hereafter referred to as laminae) and veins 
(hereafter referred to as ribs) and separated into the laminae and ribs by 
separating machines. The luminae are dried to possess 12% of water content 
for avoiding change in quality and molding during a long term storage and 
then packed in a barrel or other container (abovementioned process be 
referred to as a raw material treatment process). The packed laminae are 
stored for a long time for maturing. The laminae which have finished 
maturing are threshed into cut cigarette after the steps of leaf 
orientation, blending and flavoring. 
During the raw material treatment process, the tobacco leaves are stripped 
into laminae and ribs. The degree of this stripping gives a large 
influence upon a raw material yield and product quality. That is, the 
tobacco leaves are subjected to a great mechanical action when they are 
stripped into laminae and ribs. Accordingly insufficient separation 
between laminae and ribs is accomplished, or conversely excessive 
separation is accomplished so that the tobacco leaves are finely divided 
depending upon the physical properties possessed by the tobacco leaves. 
The physical properties depend largely on the water content and 
temperature. 
Accordingly, it is important to control the factors which give influence 
upon the quality, that is, the water content and temperature of the 
tobacco leaves supplied to rib removing machines so that they are suitable 
for the tobacco leaves and to control the mechanical impact force upon the 
tobacco leaves in the rib removing machines to a suitable value for the 
tobacco leaves. 
These controls have heretofore been manually carried out. This manual 
technique includes adjusting the water content and temperature of the 
tobacco leaves supplied to the rib removing machines to suitable values by 
controlling control valves of water and steam of the humidity controller 
in accordance with a predetermined preset manipulation condition table and 
adjusting the mechanical impact force given to the tobacco leaves in rib 
removing machines by replacing a basket with that having a different pitch 
of grid. 
It is however very difficult to manually control the quality of the tobacco 
leaves while suppressing the production of the laminae not larger than a 
given size since preliminary determination of the water content and 
temperature suitable for rib removal and the mechanical impact force 
applied to the tobacco leaves in the rib removing machine is time and man 
power consuming due to the fact that the specific physical properties of 
the tobacco leaves largely varies with the production place, weather 
conditions of the production year and the like and since it is practically 
impossible to replace the basket of the rib removing machine depending 
upon the character of the tobacco leaves which constantly changes. 
SUMMARY OF THE INVENTION 
It is therefore an object of the present invention to provide a novel 
system for controlling the lamina size in a raw material treatment process 
for tobacco leaves, which is capable of decreasing the production of the 
lamina not larger than a given size as low as possible. 
In accordance with the present invention, there is provided a system for 
controlling the lamina size in a raw material treatment process for 
tobacco leaves comprising 
measuring means for measuring the production rate of the laminae larger 
than a given size in the raw material treatment process in which the 
tobacco leaves which have been provided with a water content and 
temperature by a humidity controller are stripped into laminae and ribs by 
means of rib removing machines capable of changing a mechanical impact 
force applied upon the tobacco leaves by changing the rotational number of 
grid or threshing gear and are then separated by means of separating 
machines; and 
operational control means for receiving measurement signals from said 
measuring means as a feedback signal for searching a water content, 
temperature and rotational number of grid or threshing gear which minimize 
the production rate of the laminae not larger than a given size by a 
hill-climb method using the water content and temperature provided by the 
humidity controller and the rotational number of grid or threshing gear as 
manipulation factors.

DETAILED DESCRIPTION OF THE EMBODIMENTS 
The present invention will be described by way of an embodiment with 
reference to the drawings. 
Referring now to FIG. 1, there is shown a process for treating raw material 
of tobacco. The tobacco leaves supplied from a supplier 1 are controlled 
by a flow rate controller 2 so that they are conveyed at a predetermined 
flow rate and then are supplied to a humidity controller 3. In the 
humidity controller the tobacco leaves are provided with a flexibility 
necessary for rib removal by addition of water and steam which is sprayed 
from water and steam nozzles 25 and 26 respectively. The tobacco leaves 
which have finished humidity control are separated into laminae and ribs 
by means of rib removing machines 5, 9, 12 and 14 and furthermore 
separated by separating machines 6, 7, 8, 10, 11, 13, 15, 16 and 18. 
In FIG. 1 reference numerals 4 and 21 represent feeders; 17 a conveyer 
assembly; 20 a sampler; 22 a device for measuring the size of laminae; 23 
and 24 silos; 27 and 28 weight meters for measuring the flow rate of 
laminae. 
Each of the aforementioned rib removing machines 5, 9, 12 and 14 comprise a 
cylindrical grid member 30 having grids 29 disposed at given intervals 
therein, a truncated core member 32 within the grid member 30 having a 
plurality of threshing gears 31 disposed on the outer periphery thereof 
and a casing which encloses the grid member 30 as shown in FIG. 2. When 
the tobacco leaves are charged into a spacing between the grid member 30 
and the core member during the rotation of the grid member 30, a 
mechanical impact force acts upon the tobacco leaves from the grids 29 and 
threshing gears 31. The tobacco leaves are separated into the laminae and 
the ribs when they come out from the space between grids 29 and enter into 
the space between the grid member 30 and the casing 33. 
The rib removing machines 5, 9, 12 and 14 are capable of changing the 
mechanical impact force acting upon the tobacco leaves by changing the 
rotational number of the grid member 30 (the grid rotational number) 
and/or relative grid pitch (relative spacing between the grids 29 and the 
threshing gears 31). In other words, the threshing rate can be adjusted by 
changing the grid rotational number and/or relative grid pitch (refer to 
FIG. 3). A term threshing rate herein means a value which is obtained by 
multiplying the ratio of the laminae produced by the first rib remover 5 
to the total laminae (lamina production ratio) with a constant determined 
by the separating machines. For example, 75 per cent of threshing rate 
means that 75 percent of the total lamina is stripped by the first rib 
removing machine 5. 
The grid member 30 may be secured and the core member 32 may be rotated. In 
this case, the threshing rate is changed by changing the rotational number 
of the core member 32 (threshing gear rotational member). 
Referring to FIG. 4, there is shown an embodiment of the control system of 
the present invention. Detectors 101, 102 and 103 for detecting the water 
content, temperature and flow rate of the tobacco leaves respectively are 
disposed at the entrance of the humidity controller 3. The water content, 
temperature, and flow rate of the tobacco leaves conveyed to the humidity 
controller 3 are measured so that the measurements are applied to an 
operational device 105. The operational device 105 calculates the amount 
of water to be added upon the basis of the measurement and a preset value 
of the water content given to the tobacco leaves, which is stored in a PiD 
adjuster 106. The calculated value is a cascade preset value for a PiD 
adjuster 107. 
On the other hand, a detector 104 for detecting the water content is 
disposed at the exit of the humidity controller 3 so that the water 
content of the tobacco leaves which have been provided with water is 
measured and the measurement is applied to the PiD adjuster 106 as a 
feedback signal. 
The PiD adjuster 106 which stores a preset value of the water content given 
to the tobacco leaves compares the preset value with the measured value, 
carries out PiD compensation and provides a signal when there is a 
deviation therebetween. The output signal is added to the signal 
(calculated value) of the aforementioned operational device 105 so that 
the cascade preset value of the PiD adjuster 107 is corrected. 
The water nozzle 25 is provided with a control valve 109 which is 
controlled by an output signal from the PiD adjuster 107. The amount of 
water which is controlled by the control valve 109 is measured by the flow 
rate detector 108. When there is a deviation between the measured value 
and cascade preset value the PiD compensation is carried out by the PiD 
adjuster 107. 
A temperature detector 110 as well as the water content detector 104 is 
disposed at the exit of the humidity controller 3. The temperature of the 
tobacco leaves discharged from the humidity controller 3 is measured. The 
measurement is applied to a PiD adjuster 112 as a feed back signal. 
The preset value representative of the temperature imparted to the tobacco 
leaves is stored in the PiD adjustor 112 where the preset value is 
compared with the measurement. If there is a deviation therebetween the 
PiD adjustor PiD compensates for the deviation and outputs a signal. The 
output signal provides a cascade preset value for the PiD adjustor 113 
which controls the control valve 115 disposed at the steam nozzle 26. The 
flow rate of the steam which is controlled by the control valve 115 is 
measured by the flow rate detecting portion 114. If there is a deviation 
between the measurement and the cascade preset value, PiD compensation for 
the deviation is accomplished by the PiD adjustor 113. 
The rotational number of the grid of the first rib removing machine 5 is 
measured by a rotary meter 116. The measurement is input to a PiD adjustor 
117. 
An optional rotation number of the grid necessary for rib removing is 
stored in the PiD adjustor 117. If there is a deviation between the preset 
value and the measurement, the PiD adjustor then PiD compensates for the 
deviation and outputs a signal to a rotational number controlling motor 
118. 
The laminae which have been stripped from the tobacco leaves in the rib 
removing machine 5, 9, 12 and 14 are separated from the ribs by the rib 
removing machines 6, 7, 8, 10, 11, 13, 15, 16, 18 and then fed to a 
vibration type sifter 120. The vibration type sifter 120 comprises two 
sifters 121 and 122 having different meshes which are stacked. For 
example, the laminae not less than 25 mm are sifted by the sifter 121 and 
13-25 mm laminae are sifted by the sifter 122. The flow rate of the 
laminae which are sifted by the sifters 121 and 122 is measured by a 
measuring devices 124, 125 and 126. The measurements are input to a lamina 
size meter 22 in which the rate of production of the laminae not larger 
than 13 mm is calculated. 
The calculated value from the lamina size meter 22 is input as a feedback 
signal to an operational control device 127 in which an optimum value 
which is to be preset in the PiD adjustors 106, 112, 117 is calculated 
upon the basis of the feedback signal. 
Before the detailed description of the operation of the operational 
controller 127, the relation between the tobacco leaves charged into the 
rib removing machines 5, 9, 12, 14 and the production rate of laminae not 
larger than 13 mm and the relation between the threshing rate of the first 
rib removing machine 5 and the production rate of, the laminae not larger 
than 13 mm are described with reference to FIGS. 5 and 6 respectively. 
Referring to FIG. 5, the production rate of the laminae not larger than 13 
mm varies according to a parabolic curve. In this case, the production 
rate of the laminae not larger than 13 mm is minimal at a humidity of 
about 17%. The relation between the temperature and the production rate of 
laminae not larger than 13 mm shows the same tendency. The production rate 
of the laminae larger than 13 mm is minimal at temperature of 60.degree. 
C. 
Referring to FIG. 6, when the threshing rate of the first rib removing 
machine 5 is increased the production rate of the laminae not larger than 
13 mm in the rib removing machine 5 is increased, the production rate of 
the laminae not larger than 13 mm in the rib removing machine 5 is 
increased, but the load imposed upon the second and following removing 
machines 9, 12, 14 is decreased so that the laminae not larger than 13 mm 
produced in the rib removing machine 9, 12 and 14 is decreased. 
Accordingly when the threshing rate of the first rib removing machine 5 is 
increased the laminae not larger than from all the rib removing machines 
5, 9, 12, and 14 varies according to a parabolic curve. In this case, when 
the threshing rate of the first rib removing machine 5 is 75%, the 
production rate of the laminae not larger than 13 mm from all the removing 
machines 5, 9, 12, and 14 is minimal. 
Since the relations change according to the production place, weather 
conditions, physical properties, etc. the operational controller 127 
searches optimum values for the water content, temperature, grid 
rotational number to be preset to the PiD adjustors 106, 112 and 117 
respectively by a symplex method one of hill-climb methods which determine 
the optimal manipulation conditions upon the basis of feed back signal 
(production rate of laminae not larger than 13 mm) from the lamina size 
measuring device 22. 
FIG. 7 is a flow chart showing the operation of the operational controller 
127. In accordance with the FIG. 7 the manipulating conditions X.sub.ij 
(water content, temperature, grid rotational number) which are determined 
optimum from the past operation conditions are preset in step 1. At this 
time, the levels are combined not to intersect the results. 
The variation range (.delta..sub.j) of the manipulation condition taken 
from the graphs of FIGS. 3, 5, 6 and 8 which gives no extremely adverse 
influence to the operation conditions as determined from FIGS. 3, 5 and 6, 
is preset in step 2. The other manipulating conditions, such as optimum 
manipulation condition, are calculated in step 3 in accordance with the 
following formula. 
EQU X.sub.ij =X.sub.lj .+-..delta..sub.j 
wherein 
i represents a level (i=1.about.3), 
j represents a manipulation factor (j=1.about.3) j=1 represents a humidity, 
j=2 represents a temperature j=3 represents a grid rotational number. 
The level 1 is preset in next step 4 to carry out the experiments from 
level 1 to level 3. Manipulation condition (X.sub.ij) in step 5 is fed to 
PiD adjustors 106, 112, 117. The lamina size measuring device 22 waits the 
time until the response of the step 5 happens and the lapsed time is 
obtained in step 6. After the passage of such lapsed time, the measurement 
is input from the lamina size measuring device 22 into step 7 (the 
sampling interval of the measurements is one second and the number of 
samplings is 180). Average value and variations are calculated upon the 
basis of the measurements in step 8. The steps 5 to 8 are repeated in step 
9 a second third time. Significant test (F test) of the results after 
steps 5 to 8 have been repeated three times is carried out in step 10 by a 
statistic approach. Discrimination whether or not there is a significant 
difference among the averaged values is carried out in step 11. If these 
is a significant difference the program will go to next step 14. If there 
is not any significant difference it will go to next step 12. 
Number one is added in step 12 to the number of the times (N) and steps 4 
to 8 are repeated. The resultant number of experiments (N+1) is then 
compared with the preliminarily number of repeats preset step 13. When the 
number (N+1) is smaller than the preset number of experiments, the 
experiment is repeated from the step 1 (the steps 5 to 8 is executed so as 
to levels 1, 2 and 3). In this case, past data graphs of FIGS. 3, 5, 6 and 
8 is used again to carry out a static test. On the other hand the system 
is stopped when the number (N+1) exceeds the preset number of repeats 
experiments. Thereafter a maximum is determined from the average values of 
the level 3 (the average value under a manipulation condition which gives 
the most adverse response) in step 14. The manipulation condition which 
gives the most adverse response is omitted and a new level is calculated 
in accordance with a following formula in step 15. 
EQU X.sub.l =(1+.alpha.)X.sub.i -X.sub.i mm 
wherein 
X.sub.i is a new manipulation condition of i factor; 
X.sub.i is an average of the manipulation condition of the factor i of the 
lost time except for the manipulation condition giving the most adverse 
response; 
x.sub.i mm is the manipulation condition giving the most adverse response 
of the factor of the lost time; and 
.alpha. is a constant. 
New manipulation conditions are preset into the PiD adjustors 106, 112 and 
117 in step 16. The lamina size measuring device 22 waits the time until 
the response of the step 16 happens and the lapsed time obtained in step 
17. After the passage of lapsed time, the measurement is input from the 
lamina size measuring device 22 in step 18 (the sampling interval of the 
measurements is one second and the number of samplings is 180). Average 
value and variations are calculated upon the basis of the measurements in 
step 19. Significant test is then carried out by using the results of the 
repeats at this time and the result of repeats of the aforementioned level 
2 in step 20. The program will go back to the step 14 if there is a 
difference. It will go back to the step 12 if there is no difference. 
Stripping the laminae is repeated each time when changing the preset values 
which are to be preset to the PiD adjustors 106, 112 and 117 so that the 
preset value minimizes the production rate of the laminae not larger than 
13 mm (refer to FIG. 8). 
When the optimum values of the water content, temperature, and mechanical 
impact force to be applied are determined by the operational device 127 
and preset to the PiD adjustors 106, 112 and 117 and the tobacco leaves 
are stripped into laminae and ribs, the production rate of laminae not 
larger than 13 mm may be lowered, by about 2% compared with the 
conventional method using man power. 
Since the production rate of the laminae not larger than 13 mm is 
determined from the laminae stripped by all rib removing machines 5, 9, 12 
and 14, the response is low while the convergence to an optimal point is 
fast. Therefore in order to make the response high, the production rate of 
the laminae not larger than 13 mm is determined from the laminae stripped 
by the rib removing machine 5. That is, the laminae which have been 
stripped by the rib removing machine 5 is fed to the sifter 128 in which 
the laminae not larger than 13 mm are sifted and the flow rate of the 
sifted laminae is measured by means of weight meters 129a and 129b. Upon 
basis of the measurements the production rate of the laminae not larger 
than 13 mm is measured by a lamina size metering device 130. In this case, 
the production rate of the laminae not larger than 13 mm at the all rib 
removers 5, 9, 12 and 14 is inversely increased as shown in FIG. 6 even if 
the production rate of the laminae not larger than 13 mm is lowered by 
reducing the threshing rate at the first rib removing machine 5. Therefore 
the final target value of the production rate of the laminae not larger 
than 13 mm is preset in the operational device 127. The water content, 
temperature and grid rotational number is searched to approach the final 
target value. 
The aforementioned operational device 127 receives a signal from the 
operational device 131 as a feedback signal and has a function of 
retrieving the optimal values such as water content, temperature and grid 
rotational number. The operational device 131 receives the result of 
measurement of the weight meter 27 (the flow rate of the laminae stripped 
by the second and subsequent rib removing machines 9, 12, and 14) and the 
result of measurement of the weight meter 28 (the flow rate of the laminae 
stripped by all the rib removing machines 5, 9, 12 and 14) and calculates 
the ratio of the flow rate of the laminae stripped by all rib removing 
machines to the flow rate of the laminae stripped by the first rib 
removing machine 5 (the production ratio of laminae). 
In the aforementioned embodiment, the operational device 127 which 
determines the optimum value in accordance with the symplex method is 
used. However an operational device which determines the optimal value in 
accordance with evop method may be used. 
There is shown the case in which the production rate of the laminae not 
larger than 13 mm is measured by the lamina size measuring devices 22 and 
130. The present invention is not limited to such numerical value. The 
main object is to measure the production rate of the laminae which gives 
adverse influence upon the quality in the subsequent steps. 
The present invention includes means for measuring a production rate of the 
laminae not larger than predetermined size and means for retrieving a 
water content, temperature and mechanical impact force applied which 
minimize the production rate of laminae not larger than a predetermined 
size by a hill-climb method using water content and temperature imparted 
to the humidity controller and mechanical impact force as manipulating 
factors, said retrieving means being adapted to receive the result of 
measurement of the former measuring means. Therefore the quality control 
is possible while decreasing the production rate of the laminae not larger 
than a predetermined size as low as possible. 
Furthermore the production rate of the laminae not larger than a given size 
(13 mm) may be lowered in comparison with that obtained by the 
conventional method.