Method of and apparatus for ascertaining the hardness of rod-shaped articles of the tobacco processing industry

The reliability of mechanical testing of the hardness of cigarettes with one or more pivotable weights is enhanced by modifying the results of such testing on the basis of signals which are obtained by optically scanning the diameters of successive cigarettes prior to mechanically induced deformation. Optical scanning is carried out by triangulation with a fixedly mounted measuring head. The signals which are obtained with mechanical testing can be further influenced by taking into consideration the moisture content and/or the temperature of tobacco in tested cigarettes.

CROSS-REFERENCE TO RELATED CASE 
The method and apparatus of the present invention constitute an improvement 
over and a further development of the method and apparatus disclosed in 
commonly owned copending patent application Ser. No. 07/857,733 filed Mar. 
26, 1992 by Reinhard Hoppe and Rolf Lindemann for "Method of and apparatus 
for ascertaining the diameters of rod-shaped articles". 
BACKGROUND OF THE INVENTION 
The invention relates to improvements in methods of and in apparatus for 
ascertaining the hardness of elastically deformable rod-shaped articles of 
the tobacco processing industry. More particularly, the invention relates 
to improvements in methods of and in apparatus for mechanically testing 
plain or filter cigarettes, cigars, cigarillos, cheroots and/or other 
rod-shaped articles of the tobacco processing industry for the purpose of 
ascertaining their hardness. 
Commonly owned U.S. Pat. No. 4,974,443, granted Dec. 4, 1990 to Uwe 
Heitmann for "Method of and apparatus for ascertaining the hardness of 
cigarettes and the like" discloses the utilization of one or more 
pivotable levers which act not unlike weights and subject successive 
cigarettes of a series of such rod-shaped articles to a radially oriented 
deforming action. The extent of mechanically induced deformation is 
measured, and the results of such measurement are utilized to regulate the 
operation of the cigarette rod making or filter tipping machine in order 
to ensure that the hardness of cigarettes will match an optimum value. The 
articles to be tested are moved sideways, i.e., substantially at right 
angles to their longitudinal axes, and each lever can simultaneously 
deform two or more cigarettes of such series. 
As used herein, the term "hardness" is intended to denote the resistance of 
rod-shaped articles of the tobacco processing industry (hereinafter 
referred to as cigarettes or filter cigarettes but intended to embrace all 
kinds of rod-shaped articles of the tobacco processing industry which 
contain filter material for tobacco smoke and/or natural, reconstituted 
and/or substitute tobacco) to elastic deformation of their fillers in 
response to the application of mechanical stresses to the external 
surfaces of their wrappers. For example, such mechanical stress will be 
applied by the fingers of a person who is about to light or who is in the 
process of smoking a cigarette. The hardness of cigarettes is a function 
of the so-called filling power of shreds or filaments of tobacco or filter 
material. The filling power is the ability of a predetermined quantity of 
tobacco or filter material to fill the tubular wrapper of a rod-shaped 
article of the tobacco processing industry. Thus, the filling power is 
clearly related to the hardness of cigarettes. 
A plain or filter cigarette is likely to be subjected to a number of 
mechanical and/or other deforming stresses before it reaches the hardness 
testing station. For example, a filter cigarette is likely to be 
mechanically deformed (so that its cross-sectional outline is not an ideal 
circular outline) during subdivision of a continuous cigarette rod into 
plain cigarettes of unit length or multiple unit length, during the 
application of uniting bands of tipping paper which are used to connect 
plain cigarettes with filter plugs (such application involves rolling the 
uniting bands around coaxial plain cigarettes and filter plugs), during 
severing of filter plugs to divide filter cigarettes of double unit length 
into filter cigarettes of unit length, as well as during repeated transfer 
of cigarettes and their components from conveyor to conveyor which often 
involves attracting the cigarettes by suction and/or pressing the 
cigarettes against the peripheries of rotary conveyors by shrouds and/or 
other mechanical means. Each such treatment is likely to affect the 
cross-sectional outline of the cigarettes ahead of the mechanical hardness 
testing station. A frequent deformation is that which imparts to the 
cigarettes an oval shape and is likely to greatly affect the accuracy of 
mechanical hardness measurements which are based on the presumption that a 
cigarette to be tested has an ideal circular cross-sectional outline. An 
oval cigarette is held on its conveyor or conveyors in a predetermined 
orientation which does not change ahead of or at the hardness testing 
station because, as a rule, the cigarettes are attracted to their 
conveyors by suction. In other words, an oval cigarette is not likely to 
change its cross-sectional outline on the way toward the mechanical 
hardness testing station because it is not permitted to roll, i.e., to 
perform a movement which would be likely to at least partially restore its 
desirable circular cross-sectional outline. As a rule, testing of hardness 
is carried out while the cigarettes are confined in axially parallel 
peripheral flutes of a rotary drum-shaped conveyor having suction ports 
which communicate with the flutes and attract the cigarettes to the rotary 
conveyor, An oval cigarette which has entered a flute of such conveyor 
will remain oval during advancement past the mechanical hardness testing 
instrumentality or instrumentalities. 
OBJECTS OF THE INVENTION 
An object of the invention is to provide a novel and improved method which 
ensures more reliable measurements of the hardness of cigarettes or like 
rod-shaped articles of the tobacco processing industry. 
Another object of the invention is to provide a method of correcting 
mechanical measurements of the hardness of cigarettes for the purpose of 
compensating for eventual deviation of the shapes of cigarettes to be 
mechanically tested from an optimum shape. 
A further object of the invention is to provide a method which renders it 
possible to accurately determine the hardness of oval or otherwise 
deformed cigarettes. 
An additional object of the invention is to provide a novel and improved 
method of scanning cigarettes or analogous rod-shaped articles of the 
tobacco processing industry ahead of the mechanical hardness testing 
station. 
Still another object of the invention is to provide a method which renders 
it possible to correct the results of mechanical hardness testing in one 
or more respects. 
A further object of the invention is to provide a novel and improved 
apparatus for the practice of the above outlined method. 
An additional object of the invention is to provide an apparatus which 
constitutes an improvement over and a further development of the apparatus 
disclosed in commonly owned U.S. Pat. No. 4,974,443 to Heitmann. 
Another object of the invention is to provide the apparatus with novel and 
improved means for correcting signals which are obtained as a result of 
mechanical determination of the hardness of cigarettes or other rod-shaped 
articles of the tobacco processing industry. 
Still another object of the invention is to provide an apparatus which can 
correct signals denoting the results of mechanical testing of cigarettes 
or the like on the basis of parameters other than the shape of articles 
prior to mechanical testing. 
A further object of the invention is to provide a rod making machine which 
embodies an apparatus of the above outlined character. 
An additional object of the invention is to provide a filter tipping 
machine which embodies an apparatus of the above outlined character. 
Another object of the invention is to provide a production line for the 
making of filter cigarettes or analogous rod-shaped articles of the 
tobacco processing industry which embodies one or more apparatus of the 
above outlined character. 
SUMMARY OF THE INVENTION 
One feature of the present invention resides in the provision of a method 
of ascertaining the hardness of elastically deformable rod-shaped articles 
of the tobacco processing industry. The improved method comprises the 
steps of advancing a series of articles in a predetermined direction along 
a predetermined path wherein the longitudinal axes of the articles are at 
least substantially normal to the predetermined direction, subjecting the 
articles of the series to elastic deformation in a first portion of the 
path including applying to the articles a predetermined deforming force 
substantially radially of the articles whereby the articles develop 
depressions and the extent of elastic deformation is indicative of the 
hardness of deformed articles, monitoring the extent of elastic 
deformation and generating first signals which denote the monitored 
deformation, optically scanning at least one characteristic of the 
articles of the series in a second portion of the path upstream of the 
first portion and generating second signals which denote the at least one 
characteristics, and modifying the first signals in dependency upon the 
respective second signals. 
The scanning step can include determining a variable reference point as a 
function of the thickness of the respective article, and the monitoring 
step of such method can include utilizing the reference point as a 
starting point for measurement of the extent of deformation of the 
respective article in the first portion of the path. 
The scanning step can include measuring the distance of the external 
surfaces of articles from a predetermined fixed reference point, and the 
second signals then indicate the measured distance and hence the diameters 
of the respective (undeformed) articles. The advancing step of such method 
can comprise conveying the articles along the first portion of the path on 
a mobile support, and such method can further comprise the step of 
measuring the distance of the support from the fixed reference point. This 
is indicative of the diameter (thickness) of an article in the second 
portion of the path plus the distance of the external surface of such 
article from the fixed reference point. Thus, the diameter (thickness) of 
an article prior to deformation in the first portion of the path can be 
calculated by the simple expedient of deducting the distance between the 
variable reference point and the fixed reference point from the distance 
between the fixed reference point and the support. 
The monitoring step can include determining the thickness of deformed 
articles in the first portion of the path, and the scanning step can 
comprise determining the thickness of yet to be deformed articles in the 
second portion of the path. The modifying step of such method can comprise 
determining the difference between the thicknesses of an article in the 
first and second portions of the path because such difference corresponds 
to the extent of deformation of the article and is thus indicative of the 
hardness of the respective article. 
If the articles contain tobacco, the moisture content of such tobacco (and 
more particularly fluctuations of the moisture content) can influence the 
hardness of the articles. Therefore, the method can further comprise the 
steps of monitoring the moisture content of tobacco in the articles, 
generating third signals which denote the monitored moisture content, and 
modifying the second and/or first signals in dependency on the third 
signals. 
Changes in temperature of tobacco in the articles can also influence the 
hardness of the articles. Therefore, the improved method can further 
comprise the steps of monitoring the temperature of tobacco in the 
articles, generating additional signals which denote the monitored 
temperature, and modifying the second and/or first signals in dependency 
on the additional signals. 
Another feature of the present invention resides in the provision of an 
apparatus for ascertaining the hardness of elastically deformable 
rod-shaped articles of the tobacco processing industry. The improved 
apparatus comprises means for advancing a series of articles in a 
predetermined direction along a predetermined path wherein the 
longitudinal axes of the articles are at least substantially normal to the 
predetermined direction, a combined mechanical monitoring and deforming 
unit having means for subjecting the articles of the series to elastic 
deformation in a first portion of the path including means for applying to 
the articles a predetermined deforming force radially of the articles 
whereby the articles develop depressions and the extent of elastic 
deformation is indicative of the hardness of deformed articles, means for 
monitoring the extent of elastic deformation of articles including means 
for generating first signals denoting the monitored deformation, means for 
optically scanning at least one characteristic (such as diameter, i.e., 
thickness) of the articles of the series in a second portion of the path 
upstream of the first portion including means for generating second 
signals which denote the at least one characteristic, and signal 
processing means including means for modifying the first signals in 
dependency on the respective second signals. 
The advancing means preferably comprises at least one rotary conveyor 
having peripheral article-receiving flutes. The scanning means can include 
means for measuring the thickness of the articles radially of the at least 
one rotary conveyor, and the second signals are preferably indicative of 
variable reference values, such as the distance of the external surface of 
the scanned article from a fixed reference point on the scanning means, 
and the means for generating first signals can include means for utilizing 
the reference values as starting points for monitoring the extent of 
elastic deformation of articles in the first portion of the path. Thus, if 
the starting point is the distance of the radially outermost portion of a 
yet to be elastically deformed article from the fixed reference point on 
the scanning means, the difference between such distance and the distance 
of the bottom of the flute from the fixed reference point is indicative of 
the thickness or diameter of the article prior to deformation. 
The scanning means can comprise a measuring head which defines the fixed 
reference point adjacent the first portion of the path. The means for 
generating second signals can comprise means for generating signals which 
denote the distance of the surfaces of articles in the second portion of 
the path from the fixed reference point and means for converting signals 
which denote such distances into signals which denote the thickness of the 
respective articles. The rotary conveyor is disposed at a predetermined 
distance from the fixed reference point on the measuring head. The signal 
converting means of the modifying means in such apparatus preferably 
includes a memory for a third signal which denotes the predetermined 
distance and means for generating further signals which denote the 
differences between the third signal and the signals denoting the 
distances of the surfaces of articles in the second portion of the path 
from the fixed reference point. The measuring means can include means for 
directing at least one beam of radiation upon articles in the second 
portion of the path whereby the articles reflect at least a portion of the 
at least one beam. The measuring means (such as the aforementioned 
measuring head) can include means for intercepting the reflected portion 
of the at least one beam. The measuring means is preferably designed to 
triangulate the at least one characteristic of articles in the second 
portion of the path. 
The signal processing means of the improved apparatus can comprise means 
for evaluating the first signals and means for evaluating the second 
signals. The modifying means of such signal processing means can comprise 
a computer which has inputs for the evaluated first and second signals and 
serves to generate signals denoting the differences between the evaluated 
first signals and the respective evaluated second signals. 
If the articles contain moist tobacco, fluctuations of the moisture content 
are likely to distort the results of determination of the hardness. 
Therefore, the apparatus can further comprise means for generating third 
signals which denote the moisture content of tobacco, and the signal 
processing means of such apparatus then comprises means for modifying the 
second and/or first signals as a function of third signals. 
The temperature of tobacco in the rod-shaped articles is also a parameter 
which is likely to affect the accuracy of determination of the hardness of 
such articles. Therefore, the improved apparatus can be further provided 
with means for generating signals denoting the moisture content of tobacco 
in the articles, and the signal processing means of such apparatus further 
comprises means for modifying the second signals and/or the first signals 
as a function of signals which denote the temperature of tobacco. 
The novel features which are considered as characteristic of the invention 
are set forth in particular in the appended claims. The improved apparatus 
itself, however, both as to its construction and its mode of operation, 
together with additional features and advantages thereof, will be best 
understood upon perusal of the following detailed description of certain 
presently preferred specific embodiments with reference to the 
accompanying drawing.

DESCRIPTION OF PREFERRED EMBODIMENTS 
The construction and mode of operation of the combination of a cigarette 
rod making machine and a filter tipping machine shown in FIG. 1 are as 
follows: 
The cigarette rod making machine comprises a gate 1 which serves to 
discharge batches of tobacco particles into a first distributor 2. The 
latter is adjacent a rotary evacuating member 3 having vanes or paddles 
which transfer tobacco particles at a controlled rate into the main 
magazine 4 of a second or main distributor (also called hopper). One 
sidewall of the magazine 4 is constituted by the upwardly moving reach of 
an endless elevator conveyor 5 which delivers accurately metered portions 
or batches of tobacco particles into an upright gathering duct 6. The open 
lower end of the duct 6 is adjacent a carded drum 7 which draws a 
continuous layer of tobacco particles past a rapidly rotating picker 
roller 8. The pins of the picker roller 8 expel tobacco particles from the 
carding of the conveyor 7 and propel the thus liberated particles against 
a suitably configurated guide 9 simultaneously with pneumatic segregation 
of heavier tobacco particles (such as fragments of tobacco ribs). 
Satisfactory tobacco particles form a thin layer which is propelled 
against the underside of the lower reach of a foraminous stream building 
conveyor 10. This conveyor cooperates with a suction chamber 11 to build a 
continuous tobacco stream which contains a surplus of tobacco particles. 
The surplus is removed by a conventional adjustable trimming or equalizing 
device 12 serving to convert the stream into a rod-like filler which is 
caused to advance onto the upper side of a running web 13 of cigarette 
paper or other suitable wrapping material. The web 13 is drawn off a 
bobbin 14 which stores an expiring supply of cigarette paper, and such web 
is caused to pass through an imprinting mechanism 15 before it reaches an 
endless belt conveyor 16 (known as garniture) which draws the web and the 
tobacco filler through a wrapping mechanism 17 having means for draping 
the web around the filler to thus form a partly finished cigarette rod 
wherein one longitudinally extending marginal portion of the convoluted 
web 13 projects from the other marginal portion substantially tangentially 
of the rod. The projecting marginal portion of the draped web 13 is coated 
with a suitable adhesive which is discharged by a paster (not shown), and 
the adhesive-coated marginal portion is folded over the other marginal 
portion to form therewith a longitudinally extending seam. Such seam is 
heated by a tandem sealer 18 in order to promote setting of the adhesive 
and to strengthen the seam before the thus finished cigarette rod 19 is 
caused to pass through a density measuring apparatus 20 of any known 
design. The leader of the finished rod 19 is severed at selected intervals 
by a so-called cutoff 21 so that the rod 19 yields a succession of 
discrete plain cigarettes 22, e.g., plain cigarettes of double unit 
length. 
Conveyor belts 28, 29 are provided to transport trimmed off surplus tobacco 
from the trimming device 12 into a collecting receptacle 30 beneath the 
magazine 4 of the main distributor or hopper so that the returned surplus 
can be entrained by the elevator conveyor 5 for renewed delivery into the 
gathering duct 6. 
Successive plain cigarettes 22 of double unit length are grasped by the 
controlledly movable arms 23 of a rotary transfer mechanism 24 which 
deposits the plain cigarettes in successive axially parallel peripheral 
flutes of a rotary drum-shaped conveyor 25 forming part of the filter 
tipping machine 26. The conveyor 25 delivers the cigarettes 22 into the 
flutes of a rotary drum shaped severing conveyor 27 cooperating with a 
rotary circular knife (not shown) which divides each cigarette 22 into two 
plain cigarettes of unit length. 
The severing conveyor 27 of the filter tipping machine 26 delivers pairs of 
plain cigarettes of unit length to two aligning and spreading conveyors 31 
which deposit pairs of axially spaced apart coaxial plain cigarettes into 
successive axially parallel peripheral flutes of a rotary drum-shaped 
assembly conveyor 32. The filter tipping machine 26 further comprises a 
magazine 33 for a supply of filter rod sections of six times unit length. 
The magazine 33 discharges such filter rod sections into the flutes of a 
rotary drum-shaped severing conveyor 34 which cooperates with two rotary 
circular knives 35 serving to subdivide each filter rod section of six 
times unit length into a row of three coaxial filter rod sections or plugs 
of double unit length. The filter plugs of successive rows are staggered 
on a staggering conveyor 36 and are thereupon shuffled on a shuffling 
conveyor 37 which converts them into a single file of parallel filter 
plugs, and successive plugs of such single file enter successive flutes of 
a combined rotary cylindrical drum-shaped accelerating and inserting 
conveyor 38. The latter inserts discrete filter plugs of double unit 
length into the spaces between pairs of plain cigarettes of unit length on 
the assembly conveyor 32 so that the flutes of the conveyor 32 accumulate 
groups of three coaxial rod-shaped articles each (group) including a 
filter plug of double unit length flanked by two plain cigarettes of unit 
length. The assembly conveyor 32 delivers such groups into successive 
flutes of a rotary drum-shaped condensing conveyor 39 whereon the plain 
cigarettes are caused to abut the adjacent ends of the respective filter 
plugs. 
A bobbin or reel 41 on the frame of the filter tipping machine 26 stores a 
supply of expiring web 40 of tipping paper one side of which is coated 
with adhesive ahead of a cutting drum 42 cooperating with a rotary knife. 
A supply of fresh tipping paper (note the bobbin or reel 41a) is 
maintained in a state of readiness, and its leader is spliced to the 
expiring web 40 (supplied by the reel 41) as soon as the supply of web 40 
is nearly exhausted. 
The cutting drum 42 supplies a series of adhesive-coated uniting bands 
(sections of web 40) which are attached to successive groups in the flutes 
of the conveyor 39 before the latter delivers the groups, and the 
respective uniting bands, onto a rolling drum 43. The drum 43 convolutes 
the uniting bands around the respective filter plugs and the adjacent 
inner end portions of the respective plain cigarettes to form filter 
cigarettes of double unit length, and the drum 43 delivers finished filter 
cigarettes into the flutes of an intermediate conveyor 44 which is used to 
expel moisture from the convoluted uniting bands. The thus dried filter 
cigarettes are transferred onto a severing drum 45 cooperating with a 
rotary circular knife (not shown) to divide each filter cigarette of 
double unit length into two filter cigarettes of unit length. Each filter 
cigarette of double unit length is severed midway across the respective 
filter plug and the convoluted uniting band. 
The thus obtained two rows of filter cigarettes of unit length are caused 
to advance with the rotary drum-shaped conveyors of a turn-around device 
46 which inverts the filter cigarettes of one row and places them into the 
gaps between successive (non-inverted) filter cigarettes of the other row 
to form a single row of filter cigarettes wherein the filters of all 
cigarettes face in the same direction. The last conveyor of the 
turn-around device 46 delivers successive filter cigarettes of the single 
row into the axially parallel peripheral flutes 55 (FIG. 2) of a testing 
conveyor 47 and thence into the flutes of an ejecting conveyor 48 serving 
to segregate defective filter cigarettes from satisfactory articles. The 
ejecting conveyor 48 further comprises or cooperates with means for 
monitoring the tobacco-containing ends or heads of successive filter 
cigarettes of unit length. A rotary drum-shaped conveyor 49 accepts 
satisfactory filter cigarettes from the ejecting conveyor 48 and deposits 
them on the upper reach of an endless take-off conveyor 50. 
The heretofore described parts of the production line including the 
cigarette making and filter tipping machines shown in FIG. 1 are known and 
form no part of the present invention. The cigarette rod making machine 
can be of the type known as PROTOS which is distributed by the assignee of 
the present application, and the filter tipping machine 26 can be of the 
type known as MAX (also distributed by the assignee of the present 
application). 
The testing conveyor 47 cooperates with a monitoring device 51 which serves 
to ascertain the hardness of filter cigarettes 54 (FIGS. 2 and 3) of unit 
length. The monitoring device 51 comprises at least one lever 53 which is 
pivotable about the axis of a shaft 52 and bears, at least with its own 
weight, against a series of successive filter cigarettes 54 while the 
cigarettes advance along an arcuate path in the direction of arrow 56 
shown in FIG. 2. The cigarettes 54 which are being acted upon by the 
illustrated lever 53 in the radial direction of the conveyor 47 are 
received in the axially parallel peripheral flutes 55 each having the same 
depth and each receiving, for example, approximately one-half of the 
respective filter cigarette. The cigarettes 54 are elastically deformable, 
and the extent of their deformation (i.e., the depth of depressions 
provided therein by the lever 53) is indicative of their hardness. 
The monitoring device 51 is adjacent a first portion of the arcuate path 
for the filter cigarettes 54 in the flutes 55 of the conveyor 47, namely 
downstream of a second portion which is adjacent an optical scanning 
device 57. The latter includes a so-called measuring head or range finder 
58 which is designed to emit a beam 100 of radiation (e.g., visible light) 
against the external surfaces 54a of tubular wrappers of successive (yet 
to be deformed) filter cigarettes 54 advancing along the second portion of 
their path toward the first portion, i.e., toward the monitoring device 
51. The purpose of the optical scanning device 57 is to ascertain certain 
dimensions (particularly the thickness or diameter A) of each cigarette 54 
which is on its way toward the monitoring device 51. The diameters A of 
all cigarettes 54 which reach the scanning device 57 are not the same. 
This is due to certain deformation of cigarettes 54 during making of plain 
cigarettes in the cigarette rod making machine as well as during assembly 
of plain cigarettes and filter plugs into filter cigarettes of double unit 
length and unit length. In many instances, the cigarettes 54 which reach 
the measuring head 58 of the scanning device 57 are slightly oval, i.e., 
their cross-sectional outline departs from an ideal circular outline. If 
the cigarettes 54 are out of round before they reach the lever 53 of the 
monitoring device 51, and particularly if their deformation is pronounced 
in the radial direction of the conveyor 47 (i.e., in the direction of 
action of the lever 53 upon the adjacent cigarettes 54), deformation which 
is detected while the cigarettes 54 are acted upon by the lever 53 is 
likely to be misleading, i.e., it will not be truly indicative of the 
hardness of the respective cigarettes. 
The measuring head 58 of the scanning device 57 is fixedly mounted adjacent 
the second portion of the path for filter cigarettes 54 in the respective 
flutes 55 of the conveyor 47 and establishes a fixed reference point FRP 
at a predetermined distance AR from the deepmost portion of that flute 55 
which is nearest to the measuring head 58. The distance AM of the fixed 
reference point FRP from the nearest cigarette 54 can vary from cigarette 
to cigarette because it is indicative of the distance of the fixed 
reference point FRP from the radially outermost portion of the external 
surface 54a of the tubular wrapper of cigarette 54 at the scanning station 
60 (best shown in FIG. 3). The measuring head 58 is mounted on a fixedly 
installed carrier 59 for the shaft 52 of the lever 53 forming part of the 
monitoring device 51. 
The measuring head 58 is designed to emit the at least one beam 100 of 
radiation, and at least a portion (shown at 100a) of such beam is 
reflected back toward the measuring head by the external surface 54a of 
the tubular wrapper of the filter cigarette 54 advancing through the 
scanning station 60. The operation of the measuring head 58 is based on 
the triangulation principle, and the purpose of this measuring head is to 
ascertain the fixed distance AR from the deepmost portion of the nearest 
flute 55 to the fixed reference point FRP (prior to actual testing of 
cigarettes 54) as well as to ascertain the distance AM between a variable 
reference point RP and the fixed reference point FRP, i.e., the shortest 
distance from the external surface 54a of the tubular wrapper of a 
cigarette 54 at the scanning station 60 from the head 59. The difference 
between the distances AR and AM equals the diameter A of the filter 
cigarette 54 in that flute 55 which is nearest to the fixed reference 
point FRP. 
A presently preferred measuring head or range finder 58 is that known as 
type LC-ML-AT 30/3/10K which is distributed by the Firm Laser Components 
at D-8038 Grobenzellt Federal Republic Germany. 
The filter cigarettes 54 which advance through the scanning station 60 are 
attracted to the surfaces bounding the respective flutes 55, e.g., by 
providing the conveyor 47 with suction ports which are customary in 
conveyors for the transport of rod-shaped articles of the tobacco 
processing industry. The path of flutes 55 and of the cigarettes 54 
therein is a circular path, and the fixed distance AR is known; such 
distance can be calculated (and a corresponding signal stored in a 
suitable memory of the signal processing unit 63 (FIG. 1) of the improved 
apparatus) by triangulation (i.e., by resorting to the measuring head 58) 
prior to start of the actual scanning operation, i.e., prior to 
determination of the diameters A of yet to be deformed filter cigarettes 
54. 
The signal generating component or components of the monitoring device 51 
transmit signals denoting the reduced diameters or thicknesses B (FIG. 2) 
of successive deformed cigarettes 54 to a first evaluating circuit 61 of 
the signal processing unit 63 shown in the lower left-hand portion of FIG. 
1. The measuring head 58 of the scanning device 57 transmits signals 
denoting the diameters A of filter cigarettes 54 to a second evaluating 
circuit 62 of the signal processing unit 63. The first signals which are 
supplied by the signal generating means of the monitoring device 51 are 
indicative of the extent of deformation (indicated in FIG. 2, as at D) of 
successive filter cigarettes 54, namely of the depth of radial depressions 
which are made by the lever 53 of the monitoring device 51. The signal 
generating means of the measuring head 58 transmits signals which are 
indicative of the diameters A of the articles 54 ahead of the monitoring 
device 51, i.e., of differences AR minus AM for successive cigarettes 54. 
The diameters A are measured in the radial direction of the conveyor 47. 
The evaluating circuit 62 can be designed to average the signals denoting 
the diameters A of a certain number of successively conveyed filter 
cigarettes 54 and to make the thus obtained averaged second signals 
available for modification of the corresponding first signals furnished by 
the signal generating means of the monitoring device 51. The averaged 
first signals at the output of the evaluating circuit 61 are indicative of 
the average hardness of a selected number of successively monitored filter 
cigarettes. Analogously, the signal generating means of the monitoring 
device 51 can be designed to average selected numbers of successive first 
signals (denoting the diameters B or the extent of radial deformation of 
cigarettes 54 at the monitoring station downstream of the scanning station 
60). 
The outputs of the evaluating circuits 61, 62 are connected to the 
corresponding inputs of a computer 64 which forms part of the signal 
processing unit 63 and is designed to modify the first signals (from 61) 
in dependency upon the corresponding second signals (from 62) in order to 
take into consideration the fact that the diameters A of the cigarettes 54 
reaching the scanning station 60 do not always match an optimum or desired 
diameter such as would be necessary to ensure that the lever 53 of the 
monitoring device 51 will subject each and every article 54 at the 
monitoring station to identical deforming action. 
The temperature of tobacco in the filter cigarettes 54 is likely to vary 
while the filter tipping machine 26 is in operation. Variations of tobacco 
temperature are likely to result in a distortion of measurements which are 
carried out by the monitoring device 51. Therefore, the apparatus of the 
present invention preferably further comprises a temperature monitoring 
device 65 which transmits signals denoting the temperature of tobacco, and 
such signals are transmitted to the computer 64 which modifies the first 
signals accordingly. As a rule, heating of tobacco to an elevated 
temperature is likely to influence the operation of the monitoring device 
51 in such a way that the first signals transmitted to the evaluating 
circuit 61 are indicative of a lesser hardness (i.e., of a hardness which 
is less than actual hardness), and that the presence of relatively cool 
tobacco will induce the device 51 to generate signals which indicate that 
the hardness of cigarettes 54 exceeds the actual hardness. The computer 64 
modifies the first signals in dependency on the intensity and/or other 
characteristics of signals which are transmitted by the temperature 
monitoring device 65 so that the hardness signals at the output of the 
computer 64 more accurately reflect the actual hardness of the monitored 
cigarettes 54. The device 65 can be of the type known as KT15 distributed 
by the Firm Heimann, Federal Republic Germany. This device is installed in 
or adjacent the conveyor 47. 
Fluctuations of the moisture content of tobacco in the cigarettes 54 are 
also likely to adversely influence the accuracy of first signals from the 
monitoring device 51 to the evaluating circuit 61 and thence to the 
computer 64. A higher moisture content of tobacco will induce the device 
51 to generate first signals which are indicative of lesser than actual 
hardness, and a lower moisture content of tobacco will induce the device 
51 to generate signals which are indicative of greater than actual 
hardness. Therefore, the improved apparatus further comprises a device 66 
which determines the moisture content of tobacco (e.g., adjacent the 
gathering duct 6 of the cigarette rod making machine) and transmits 
appropriate signals to the computer 64 which processes such signals to 
modify the first signals from the evaluating circuit 61 and to thus ensure 
that the signals at the output of the computer are more accurately 
indicative of the actual hardness of tested articles 54. The device 66 can 
be of a type well known in the tobacco processing field, e.g., a moisture 
measuring device of the type distributed by the assignee of the present 
application. 
Signals which are transmitted by the output of the computer 64 are 
displayed at 67 and/or utilized to control the operation of the surplus 
removing trimming or equalizing device 12 and to thus automatically 
compensate for deviations of actual hardness from desirable optimum 
hardness of the rod-like filler which is converted into the tobacco 
containing portion of the cigarette rod 19. 
The mode of operation of the improved hardness ascertaining apparatus is as 
follows: 
The beam 100 at the scanning station 60 of FIG. 3 is used first while the 
flutes 55 of the conveyor 47 are empty, namely to ascertain the fixed 
distance AR from the fixed reference point FRP to the deepmost portion of 
the flute 55 at the scanning station 60, i.e., of the flute nearest to the 
measuring head 58. A corresponding signal is transmitted to and is stored 
as a reference signal in a memory of the signal processing unit 63. 
The conveyor 47 thereupon begins to transport discrete filter cigarettes 54 
in successive flutes 55, and the measuring head 58 proceeds to determine 
the distances AM, i.e., the distances of the fixed reference point FRP 
from the (non-fixed) reference points RP denoting the radially outermost 
portions of external surfaces 54a of tubular wrappers of cigarettes 54 at 
the scanning station 60. In order to enhance the accuracy of determination 
of the distance AM (which can vary from cigarette to cigarette), the 
measuring head 58 is preferably designed to store a series of signals 
denoting different distances of an article 54 advancing through the 
scanning station 60 from the fixed reference point FRP. This is indicated 
in FIG. 3 by a curve 68 within a window 69 of the measuring head 58. The 
measuring head 58 can select an extreme value (e.g., the value 68a 
denoting the shortest distance of an article 54 at the station 60 from the 
measuring head 58) for transmission of a corresponding (second) signal to 
the evaluating circuit 62 in the signal processing unit 63. The evaluating 
circuit 62 further receives the reference signal denoting the fixed 
distance AR and determines the distance AR-AM=A. A corresponding signal, 
denoting the diameter or thickness A of the article 54 at the station 60, 
is transmitted to the respective input of the computer 64 for use to 
modify the corresponding first signal from the evaluating circuit 61. 
As mentioned above, the cigarettes 54 in the flutes 55 are preferably 
attracted to the conveyor 47 by suction (or are mechanically urged against 
the surfaces bounding the respective flutes 55) so that the orientation of 
cigarettes 54 relative to the conveyor 47 does not change during 
advancement from the scanning station 60 (measuring head 58) to the 
monitoring station (device 51). This ensures, that the lever 53 of the 
monitoring device 51 deforms the cigarettes 54 radially in the same 
direction in which the diameters A of the cigarettes were ascertained at 
the scanning station 60. Therefore, the ascertained distance AM or the 
variable reference point RP is preferably utilized as a starting distance 
or reference point for determination of the extent of radial deformation 
of successive cigarettes 54 by the lever 53. Otherwise stated, the 
monitoring device 51 can ascertain the distance between the radially 
outermost portions (point RP in FIG. 3) of the external surfaces 54a of 
the tubular wrappers of yet to be deformed cigarettes 54 and the flats D 
of the same cigarettes at the monitoring station. The corresponding 
(first) signals are transmitted to the evaluating circuit 61 which also 
receives the reference signal denoting the fixed distance AR so that it 
can transmit to the computer 64 signals denoting the radial thicknesses B 
of cigarettes 54 at the monitoring station adjacent the lever 53. The 
computer 64 thereupon ascertains for each filter cigarette 54 the 
difference A-B which is indicative of the extent of radial deformation of 
cigarettes by the lever 53 and of the hardness of the respective 
cigarettes. As mentioned above, the computer 64 can influence the 
difference A-B in dependency on signals from the temperature monitoring 
device 65 and/or from the moisture detector 66 to further reduce the 
likelihood of departure of indications at 67 from actual hardness of the 
respective filter cigarettes. 
FIG. 1 shows a signal processing unit 63 in the form of a block diagram. 
Such illustration has been selected for convenience of description of the 
mode of operation of the signal processing unit 63. In actual practice, 
especially in sophisticated modern production lines for the making of 
plain or filter cigarettes, cigars, cigarillos or other rod-shaped 
articles of the tobacco processing industry, the signal processing unit 63 
constitutes an integrated circuit of a computer which does not exhibit 
discrete components in the form of evaluating circuits, memories and/or 
others but performs all of the above functions with the same results. 
The present invention is based on the recognition that the radial dimension 
(diameter A in FIG. 3) of a cigarette 54 prior to mechanical hardness 
testing at the station for the lever 53 is of considerable importance for 
the accuracy of mechanical determination of hardness because the lever 53 
deforms successive cigarettes 54 in the same direction (radially of the 
conveyor 47) in which the measuring head 58 operates to measure the 
diameters A of cigarettes which are about to be deformed during 
advancement past the monitoring device 51. Thus, if each of the cigarettes 
54 approaching the monitoring device 51 would have an ideal circular 
cross-sectional outline, advance determination of the diameters A ahead of 
the device 51 would be unnecessary because mechanical deformation of each 
cigarette 54 would start at the same distance (matching the ideal diameter 
of a cigarette 54) from the deepmost portion of the flute 55 at the 
mechanical monitoring station. However, and since this is not the case 
because each cigarette 54 approaching the lever 53 is likely to be at 
least slightly out of round, optical determination of the diameters A 
ahead of the monitoring device 51 ensures that the signals denoting the 
extent of mechanical deformation of successive cigarettes by the lever 53 
can be corrected by taking into consideration the actual diameters A of 
successive cigarettes before they reach the mechanical hardness testing 
station. It can be said that the measuring head 58 ascertains a variable 
reference point RP ahead of the lever 53 to thus enable the signal 
processing unit 63 to determine the exact extent of radial deformation of 
cigarettes 54 by the lever 53 in that the signal which are transmitted by 
the evaluating circuit 61 and are modified by the computer 64 denote the 
actual extent of radial deformation of each cigarette 54 regardless of the 
initial diameters A of such cigarettes. In other words, the reference 
points RP are the starting or zero points for determination of the extent 
of radial deformation of successive cigarettes 54 during travel past the 
lever 53. The construction of signal generating means forming part of the 
monitoring device 51 can be the same as that of the monitoring device 
which is disclosed in the aforementioned commonly owned U.S. Pat. No. 
4,974,443 to Heitmann. 
An advantage of the computer 64 is that, in its simplest form, this 
component of the signal processing unit 63 can be designed to furnish 
signals which denote the differences between the diameters A and B of 
successive optically scanned and mechanically tested cigarettes 54 whereby 
the difference A-B accurately denotes the extent of radial deformation of 
the cigarettes by the lever 53 and hence the actual hardness of tested 
articles. Thus, the number of steps which must be carried out to correct 
the signals from the signal generating means of the monitoring device 51 
on the basis of optical scanning at the station 60 can be reduced to a 
minimum without affecting the accuracy and reliability of information 
which is displayed at 67 and/or of signals which are transmitted from the 
computer 64 to the trimming or equalizing device 12 in order to alter the 
hardness if the monitored and corrected hardness does not match an optimum 
value. 
As described hereinabove, the signal processing unit 63 is or can be 
designed to ascertain a corrected hardness value for each of a short or 
long series of successively tested cigarettes 54. However, it is often 
preferred to avoid individual correction of mechanical testing of each and 
every cigarette 54 of the series by designing the evaluating circuit 61 
with a view to furnish first signals each of which is indicative of the 
average (mechanically determined) hardness of two or more successive 
cigarettes 54, and by designing the signal generating means of the optical 
scanning device 57 with a view to furnish second signals each of which is 
indicative of the average diameter A of a number of successive cigarettes 
54 advancing past the measuring head 58. 
Referring again to FIG. 3, the optical scanning operation at the station 60 
can be simplified by designing the measuring head 58 in such a way that it 
generates a single signal during advancement of a cigarette 54 past the 
fixed reference point FRP. However, the results of determination of the 
diameter A of a cigarette 54 at the scanning station 60 are much more 
accurate and reliable if the optical testing involves the generation of a 
set of signals (as denoted by the curve 68 in the window 69) and by 
selecting the weakest or the strongest signal (particularly the signal at 
68a denoting the minimum distance of an article 54 from the point FRP) as 
that (second) signal which is transmitted to the evaluating circuit 62 and 
thence to the computer 64. 
Without further analysis, the foregoing will so fully reveal the gist of 
the present invention that others can, by applying current knowledge, 
readily adapt it for various applications without omitting features that, 
from the standpoint of prior art, fairly constitute essential 
characteristics of the generic and specific aspects of our contribution to 
the art and, therefore, such adaptations should and are intended to be 
comprehended within the meaning and range of equivalence of the appended 
claims.