Apparatus for detecting a gap in the junction area on a folded box

An apparatus for detecting a gap in the junction area on a folded box which is made of a sheet of smooth corrugated fiberboard by folding the latter while both the folded ends are located opposite to one another with the gap interposed therebetween. The apparatus includes detectors which are disposed along the moving track of the folded box. Each of the detectors includes a slit formed on the moving track at a substantially right angle relative to the latter, the width of the slit being dimensioned more than that of the gap in the junction area on the box, two inclined passages formed in the detector to reach the slit, each of the inclined passages having the substantially same inclination angle relative to the moving track, a light beam emitting mechanism disposed in one of the inclined passages to emit light beam toward the slit and a number of optical fibers longitudinally disposed in the other inclined passage so as to allow reflected light beam to be transmitted therethrough. According to the invention it is possible to detect abnormality relative to quality of the folded box and moreover carry out monitoring in the course of many steps of production. When an incorrectly folded box is detected, it is removed from the production line by operating a removing device which can be operatively associated with an automatic control system. Thus, maintaining high quality of products and saving of manpower are assured.

BACKGROUND OF THE INVENTION 
(i) Field of the Invention 
The present invention relates to a detecting apparatus for monitoring 
abnormality during the step of producing a folded fiberboard box in a 
fiberboard box making machine and more particularly to an apparatus for 
detecting abnormality relative to quality of a folded box at the 
production stage where a sheet of corrugated fiberboard is folded while 
both the folded ends are located opposite to one another with a certain 
gap interposed therebetween. 
(ii) Prior Art Statement 
The conventional box making machine is constructed so as to make a 
fiberboard box by folding a square sheet of smooth corrugated fiberboard 
which is cut to predetermined dimensions by means of a corrugator which 
serves as a preprocessing line. Specifically, it has many functions which 
comprise cutting of unnecessary corners, scribing of contour lines, 
printing, folding, gluing and preforming prior to assembling. Due to fact 
that the conventional box making machine has various processing functions 
as mentioned above, each of processing functions is achieved by operating 
a specially designed unit and a series of fiberboards are successively 
conveyed while a certain distance is maintained between the adjacent 
fiberboards at every time when a certain function is completed in a series 
of processing units. 
FIG. 6 is a fragmental schematic side view of the conventional box making 
machine. In the drawing reference numeral 1 designates a folded fiberboard 
box which is made of a sheet of smooth corrugated fiberboard by folding 
the latter in a folding unit. After completion of making of the folded box 
1 the latter is discharged from the folding unit by rotating a pair of 
guide rolls 3 and thereafter thus discharged boxes 1 are piled one above 
another in the space as defined between both retaining plates 4 in the 
layered structure. After a number of folded boxes 1a are piled one above 
another in the above-described manner, the lowermost folded box 1b is 
conveyed away from the layered structure to reach the next processing unit 
6 such as a counter unit or the like and this step of operation is 
repeated successively. 
However, it is found with respect to the conventional box making machine 
that abnormality relative to quality as corrugated fiberboard box tends to 
take place in the area located in vicinity of the above-mentioned units in 
the following manner. FIG. 7 shows a folded box 1b as seen in the 
direction as identified by an arrow mark VII in FIG. 6, wherein FIG. 7(A) 
shows a normally folded box by way of perspective view and FIG. 7 (B) 
shows a corrugated fiberboard box which is incorrectly folded in the 
so-called fishtail shape with some projection from the folded part 
recognized. In the case as shown in FIG. 7(B) the gap in the junction area 
has a dimension of G.sub.1 at the upper part but it has a different 
dimension of G.sub.2 at the lower part of the folded box as seen in the 
drawing. 
This abnormality in shape takes place when folding lines, that is, working 
lines are scribed incorrectly. In some case it takes place because of 
incorrect relative displacement of the folded part which is caused under 
the influence of shearing force which is developed during conveyance of 
the folded box 1b while the latter is depressed by many other folded boxed 
1a. Once such an incorrectly folded box is produced, this leads to 
reduction of commercial value thereof. In addition it is necessary to keep 
some inspectors in a stacker section in order to inspect quality of all 
products to remove incorrectly folded boxes. 
SUMMARY OF THE INVENTION 
Hence, the present invention has been made with the foregoing background in 
mind and its object resides in providing an apparatus for detecting 
abnormality relative to quality of folded boxes which is entirely free 
from the drawbacks inherent to the conventional apparatus as mentioned 
above. 
Another object of the present invention is to provide an apparatus for 
detecting abnormality appearing in the junction area on a corrugated 
fiberboard folded box immediately after completion of folding or adhering 
operation in a box making machine. 
To accomplish the above objects there is proposed according to the 
invention an apparatus of the earlier-mentioned type which is constructed 
in the following manner. 
(I) An apparatus for detecting a gap in the junction area on a folded box 
which is made of a sheet of smooth corrugated fiberboard by folding the 
latter while both the folded ends are located opposite to one another with 
the gap interposed therebetween, characterized in that the apparatus 
includes detectors disposed along the moving track of the box in the 
spaced relation, wherein each of the detectors includes a slit formed on 
the moving track at a substantially right angle relative to the latter, 
the width of the slit being dimensioned more than that of the gap in the 
junction area on the box, two inclined passages formed in the detector to 
reach the slit, each of the inclined passages having the substantially 
same inclination angle relative to the moving track, a light beam emitting 
mechanism disposed in one of the inclined passages to emit a light beam 
toward the slit and a number of optical fibers longitudinally disposed in 
the other inclined passage so as to allow reflected light beam to be 
transmitted therethrough. (II) An apparatus for detecting a gap in the 
junction area on a folded box which is made of a sheet of smooth 
corrugated fiberboard by folding the latter while both the folded ends are 
located opposite to one another with the gap interposed therebetween, 
characterized in that the apparatus includes detectors disposed along the 
moving track of the box in the spaced relation, wherein each of the 
detectors includes a slit formed on the moving track at a substantially 
right angle relative to the latter, the width of the slit being 
dimensioned more than that of the gap in the junction area on the box, two 
inclined passages formed in the detector to reach the slit, each of the 
inclined passages having the substantially same inclination angle relative 
to the moving track, a light beam emitting mechanism disposed in one of 
the inclined passages to emit light beam toward the slit, a number of 
optical fibers longitudinally disposed in the other inclined passage so as 
to allow reflected light beam to be transmitted therethrough and output 
processing means for converting thus transmitted light beam into electric 
signal, calculating the electric signal and generating output in response 
to thus calculated signal. 
According to the invention the apparatus is so constructed that it includes 
detectors each of which is formed with a slit on which a gap in the 
junction area on a folded box is adapted to move, the width of the slit 
being determined more than that of the gap, wherein each of the detectors 
includes two inclined passages both of which are extended at a 
predetermined inclination angle to reach the slit, one of the inclined 
passages having a bundle of optical fibers and/or a light source disposed 
therein so as to allow light to be emitted toward the slit and the other 
one having another bundle of optical fibers disposed therein through which 
reflected light beam is transmitted toward the output processing means. 
Thus, when light beam projected on the gap in the junction area on a 
folded box through the slit fails to be received by means of the bundle of 
optical fibers through which reflected light beam is transmitted, this 
leads to no generation of output in response to receipt of reflected light 
beam, resulting in the gap in the junction area being detected. 
It should be noted that receipt of reflected light beam and failure of 
receipt of the same are converted into electric signal which is then 
calculated to generate output. 
Owing to arrangement of the apparatus of the invention the following 
advantageous features are assured. 
The apparatus of the invention makes it possible to detect abnormality 
relative to quality of folded boxes made of smooth corrugated fiberboard 
and moreover carry out monitoring during the steps of production. Thus, 
any incorrectly folded box can be removed from the box production line by 
operating a removing device or the like which is operatively associated 
with an automatic control system. As a result, high quality of products 
and saving of manpower are assured.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Now, the present invention will be described in greater detail hereunder 
with reference to the accompanying drawings which schematically illustrate 
preferred embodiments thereof. 
FIG. 1 is a fragmental side view of a box making machine in which a 
detecting apparatus in accordance with an embodiment of the invention is 
incorporated. FIG. 2 is a fragmental plan view of the machine as seen in 
the direction as identified by an arrow mark II in FIG. 1. FIG. 3(a) is an 
enlarged sectional side view taken on line III--III in FIG. 2, 
particularly illustrating how a light beam emitting section and a light 
beam receiving section are arranged. FIG. 4 is another sectional view 
taken in line IV--IV in FIG. 3(a). FIG. 5 is an enlarged sectional side 
view similar to FIG. 3(a), particularly illustrating the detecting 
apparatus in accordance with another embodiment of the invention. 
In the drawings reference numerals 7 and 7a designate a detecting block 
respectively which is located at the position in the proximity of a gap 
which appears in the junction area of a folded corrugated fiberboard box 
(hereinafter referred to as folded box or box). The detecting block 7 
serves as a detector which is located just behind a folding unit 2 in 
which folding operation is performed for a series of corrugated 
fiberboards, whereas the detecting block 7a serves as a detector which is 
located behind a piling section in which a plurality of folded boxes 1a 
are piled one above another in the layered structure while certain 
adhesive force is imparted to each of the boxes. It should be noted that 
the present invention should not be limited only to their arrangement as 
shown in the drawings. Alternatively, they may be located at any properly 
determined position. As is apparent from FIG. 2, the detector 7 is formed 
with a slit 8 of which width is dimensioned more than the distance of the 
gap G in the junction area of the box 1. Further, as shown in FIG. 3(A), 
the detector 7 includes a light beam emitting passage 9 and a light beam 
receiving passage 10 both of which extend toward the slit 8 in the 
inclined state until they intersect one another there. A bundle of optical 
fibers 11 are inserted through the light beam emitting passage 9 and one 
end of the optical fibers 11 is jointed to a light source 12 from which 
light beam is emitted. On the other hand, a bundle of optical fibers 13 
are inserted through the light beam receiving passage 10 and one end of 
the optical fibers 13 is jointed to an output processor 14. 
FIGS. 3(B) and (C) schematically show other examples of the output 
processor 14. Referring to FIG. 3(A) again, the output processor 14 has a 
plurality of light beam receiving elements 15 such as photo-transistor, 
photo-diode or the like which are connected to the optical fibers 13 
through which received light beam is transmitted thereto and the light 
beam receiving elements 15 are electrically connected to a calculator 17 
via a plurality of amplifiers 16. Specifically, the calculator 17 is so 
constructed that recognizing is digitally effected with the aid of 
function to be described later as to whether light beam is received or 
not, conversion of thus obtained result to an amount of gap G in the 
junction area of a single box is carried out and moreover fluctuation in 
amount of gap in the junction area is checked so as to generate a signal 
which represents abnormality relative to quality. 
Next, the output processor as shown in FIG. 3(B) is so constructed that the 
bundle of optical fibers 13 are jointed to a single light beam receiving 
element 18 which is in turn electrically connected to the calculator 20 
via a single amplifier 19. In this case the calculator 20 is so 
constructed that electrically converted signal relative to an intensity of 
received light beam is analogically recognized with the aid of function to 
be described later and conversion of thus recognized signal to an amount 
of gap G in the junction area is then carried out so as to generate signal 
which represents abnormality relative to quality. On the other hand, the 
output processor as shown in FIG. 3(C) is so constructed that light beam 
which is received via a plurality of longitudinally arranged optical 
fibers 13 is collected by means of a lens 21 and thus collected light beam 
is detected by means of an image sensor 22 which is in turn electrically 
connected to the calculator 24, via a single amplifier 23. Received light 
beam is analogically recognized in the calculator 24 in the same manner as 
in the case shown in FIG. 3(B) whereby it is processed therein in the form 
of signal. 
Next, FIG. 5 schematically illustrates a detecting apparatus in accordance 
with another embodiment of the invention in which another type of light 
beam section is employed. Instead of the light beam emitting optical 
fibers in the foregoing embodiment the combination of lamp 25 such as 
tungsten lamp or the like and lens 26 is incorporated in the light beam 
emitting passage 9. 
Next, operation of the detecting apparatus of the invention as constructed 
in the above-described manner will be described below. 
A smooth corrugated fiberboard (hereinafter referred to simply as 
fiberboard) is processed by way of the steps of printing in a printing 
unit (not shown), slitting in a slotter unit (not shown), folding in the 
folding unit 2 to form a box 1, piling in the piling section in the 
layered structure and then moving to the next unit. During the steps of 
processing as mentioned above the box 1 or 1b moves past the detector 7 or 
7a. At the time when it moves past there the gap G in the junction area of 
the box 1 or 1b is caused to move across the slit 8 of the detector 7 or 
7a. At this moment the gap G is exposed to light beam which is transmitted 
from the light source 12 or the lamp 25 via the optical fibers 11 or the 
lens 26 in the light beam emitting passage 9. As shown in FIGS. 3(A) and 
4, light beam projected on the area excluding the gap is reflected in the 
direction as identified by an arrow mark P and thus reflected light beam 
is then transmitted through the optical fibers 13. However, light beam 
projected on the gap area is reflected in the direction as identified by 
an arrow mark Q, resulting in thus reflected light beam failing to be 
transmitted through the optical fibers 13. 
Thus, light beam reflected from the area excluding the gap in the junction 
area is transmitted through the optical fibers 13 and it is then 
represented by the word of "brightness", whereas light beam from the gap 
area is represented by the word of "darkness". Brightness and darkness as 
mentioned above are identified by means of the light beam receiving 
elements 15 in the output processor 14 in FIG. 3(A) and the result of 
identification is transmitted to the calculator 17 in the form of ON-OFF 
signal which is an output signal from the amplifiers 16. Thus transmitted 
signal is converted to an amount of gap G in the junction area in the 
calculator 17 whereby fluctuation of an amount of gap G in the junction 
area of a single box can be checked easily and reliably. When it is found 
that amounts of gaps G.sub.1 and G.sub.2 exceed a predetermined allowable 
value, an alarm signal which represents abnormality relative to quality of 
the box is generated, as is the case shown in FIG. 7(B). 
In the case of the output processor as shown in FIG. 3(B), output from the 
optical fibers 13 relative to brightness and darkness is received by means 
of a single light beam receiving element 18 and an intensity of received 
light beam is electrically converted to signal in the form of analogical 
signal which corresponds to an amount of gap in the junction area. On the 
other hand, in the case of the output processor as shown in FIG. 3(C), 
resolution is improved remarkably compaired with the case in FIG. 3(B). 
Owing to this a reduced amount of received light beam along the boundary 
of the gap in the junction area can be clearly resolved and identified. In 
this case the calculator 24 functions in the same manner as the 
first-mentioned calculator 20. 
While the present invention has been described above only with respect to a 
few preferred embodiments, it should of course be understood that it 
should not be limited only to them but various changes or modifications 
may be made in any acceptable manner without departure from the spirit and 
scope of the invention as defined by the appended claims.