FIELD OF THE ART
[0001] The present invention relates to a conveyor system for carrying planar objects by
way of a conveyor belt and the like.
BACKGROUND OF THE INVENTION
[0002] Corrugated cardboard boxes have been designed with a variety of sizes, shapes and
in a variety of multicolor printings these days, and in coping with such designs,
there have been presented a variety of functions of the machine for manufacturing
the corrugated cardboard boxes, accordingly. Now, referring to the conventional construction
of the corrugated cardboard box manufacturing machine with reference to FIGS. 1 through
4, there are shown provided a blank board supply station 1, a first printing machine
2, a second printing machine 3, printing cylinders 4, a transfer conveyor 5, a rotary
die cutting station 6, a anvil cylinder 7, a die-cut cylinder 8, a die element 9,
a board delivery conveyor (a scrap conveyor; a conveyor for a planar object) 10, a
sheet of corrugated board 11, a died board 11' (through the single-cutting process),
a died board 11" (through the double-cutting process), a stacker-conveyor 12, a counter-stacker
13, a board stopper 14, a spacing 16, a lifter 17, and a counting photoelectric tube
18, wherein a sheet of corrugated cardboard 11 is fed for printing by the board supply
station 1 with such a rate of delivery of a sheet per single rotation of the printing
cylinders 4 in the printing machines 2, 3, thereafter is delivered outwardly by the
transfer conveyor 5 for having the printing ink put in the surface of a carboard 11
dried up, and then is died to a shape of cardboard box by way of the rotary die cutter
6. The die element 9 comprises a cutting knife edge or the like implanted around the
circumferential surface of a curved veneer board of a specified thickness, which is
to be mounted onto the die-cut cylinder 8 by using bolts, and is adapted to cut and
die a sheet of carboard 11 to be fed from the foregoing step into the nip with the
anvil cylinder 7, which is wrapped with a layer of urethane rubber or the like for
making the cutting easier and preventing the wear of cutting edge, with a predetermined
timing of cuting and dieing. The delivery conveyor (scrap conveyor) 10 is formed by
a plurality of such carrier members as V-shaped belts or ropes having a circular section
in an attempt to promote the dropping of chippings and cuttings from the product at
the area where there is provided a specific means such as an air blower or a vibrator,
and is constructed in a duplex structure for carrying the died board 11' in a sandwiched
relationship over to a stacker-conveyor 12. There is provided a suction equipment
in the stacker-conveyor 12. which is adapted to attract by sucking and deliver the
died cardboard 11' at a slow speed in the attempt to reduce a impact shock of the
board against the cardboard stopper 14 provided in the counter-stacker 13 when hit,
thus obviating a possibility of damages and/or irregular stacking of the cardboards
from occurring when stacked upon the lifter 17. Also, the cardboard stopper 14 is
designed shiftable back and forth by way of a hydraulic cylinder or the like in accordance
with a given width of the died board 11' as schematically shown in FIGS. 1 and 2.
[0003] The cardboard box manufacturing machine is of the type that a sheet of cardboard
11 may be set either for one-piece cutting or for longitudinal double-piece cutting
according to the size of a box to be died by using the die element 9 of the rotary
die cutter 6. FIG. 3(111) shows the case of the single-piece cutting process, FIG.
4(111) shows the longitudinal double-piece cutting, and FIG. 4(IV) shows the four-piece
cutting process (double-cuttings in the transversal and longitudinal ways making four
pieces of boards), respectively. The die element 9 is to be set in the circumferential
surface of the die cut cylinder 8, with a single-piece or double-piece cutting knife
element implanted in working position in accordance with the size of a product box
to be manufactured, and with a spacing 16. This spacing 16 is provided for the reduction
of conveying speed in consideration of a too great shock to be given to the died cardboard
11' when hit against the cardboard stopper 14, which is taken in the following manner;
when a series of died cardboards 11' after being died by the die cut cylinder 8 are
stacked upon the lifter 17 by using the stacker-conveyor 12, as the carrying speed
of the stacker-conveyor 12 will, when the single-piece cutting is conducted (FIG.
3(111)), bring a too large shock on the died sheet 11' when hit against the cardboard
stopper 14, if V
1 V
2 (the circumferential speed of the die cut cylinder 8 and the carrying speed of the
delivery conveyor 10 are V
2, and the carrying speed of the stacker-conveyor 12 is V
1 , as shown in FIG. 3(I)), the speed V
1 of the stacker-conveyor 12 is then reduced by using the spacing 16 as shown in FIG.
3(II) to:
However, in the case of the double-piece cutting process (FIG. 4(III)), when the carrying
speed V
1 of the stacker-conveyor 12 is reduced down to V = V
2 ×ℓ/L as shownin FIG. 4(II), since the sheet 11" died for the double-cutting process
is cut to the shape in which the foregoing piece and the following piece are left
connected with each other by the die cutter, it would not be feasible to have normal
cutting operation as these died sheets 11" may come to overlap one upon the other,
and consequently, the carrying speed V
1 of the stacker-conveyor 12 is forcibly made V
1 V
2 as shown in FIG. 4(1) (identical with FIG. 3(1)), then resulting in such undesirable
problems that the leading edges of the died sheet 11" would be damaged by a too large
shock load when hit against the cardboard stopper 14 in stacking, or the died sheets
11" would be stacked irregularly.
DISCLOSURE OF THE INVENTION
[0004] In consideration of the problems noted above, it is an object of the present invention
to provide an improved conveyor system for planar objects which can obviate such a
possibility of damages to be received while being stacked or an inconvenience of irregular
stacking in the step following the die-cutting process.
[0005] In the conveyor system according to the present invention, there are provided a detecting
device adapted to detect the current end position of a planar object fed from the
preceding step, a delivery member adapted to deliver the planar object while having
it sandwiched therebetween, and a speed change device adapted to change the delivery
speed of the delivery member in accordance with the timing of the following step on
the basis of the signal from the detecting device, and as the conveying speed of the
following stacker-conveyor can be made as slow as V
I = 2ℓ/L even with the died sheet processed in the double-piece cutting operation,
there is attained such advantageous effects as avoiding the risk of damaged rendered
at the leading edge of a died sheet or the inconveniences of irregular stacking while
being stacked upon the stacker-conveyor in the following step, accordingly.
[0006] In addition, there are required only such simple delivery members as two small-diametered
sandwiching rolls to be driven for the delivery of the processed sheets, which would
have a relatively small inertia value GD
r and therefore require a relatively small capacity driving motor, thus contributing
to the curtailment of cost, and which is proven to be adaptable to the double-sheet
cutting operation and so useful in the application to the general purpose machine
for manufacturing the corrugated cardboard boxes.
[0007] The present invention will now be described taking the reference to preferred embodiments
thereof shown in the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008]
FIG. 5 is a schematic diagram illustrating the mutual relationship of a series of
planar objects aligned on the delivery to the delivery member according to the present
invention;
FIG. 6 is a side elevational view showing a preferred embodiment of the conveyor system
for the planar objects according to the present invention;
FIG. 7 is an illustrative diagram for depicting the function of the conveyor system;
FIG. 8 is a front elevational view showing the speed change device and parts relative
thereto of the conveyor system;
FIG. 9 is a front elevational view showing the same speed change device and parts
relative thereto by way of another embodiment; and
FIG. 10 is a general side elevational view showing the delivery member construction
by way of another embodiment.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0009] Shown in FIG. 6 are an anvil cylinder 7, a die-cut cylinder 8, a die element 9, a
sheet delivery conveyor (scrap conveyor) 10, a died sheet (through the double-piece
cutting process) 11", a stacker-conveyor 12, a counter-stacker 13, a spacing 16, an
photoelectric tube 32, and a sandwiching roll section 31, and shown in FIG. 8 are
sandwich (rubber) roll elements 34, 34, a bearing 35, gears 36, and a DC (variable
speed) motor 37. Also, FIG. 5 is a schematic diagram showing a series of died sheets
① through ⑥ before delvered from the sandwich roll elements 34, 34, in which L depicts
the circumferential length of the die-cut cylinder 8. Also in FIG. 7 there is shown
a timing chart showing the changes of rotating speed of the sandwich roll elements
34, 34. The sandwich roll elements 34, 34 shown in FIG. 8 are fixed in operative position
on a single roll shaft 33 disposed with a given gap, and are arranged opposedly to
respectively form a pair of rolls in the sandwiching roll section 31. Each of these
sandwich roll elements 34 is formed with a layer of soft rubber sheet in its circumference
so that it may not squeeze and crush the corrugated cardboard sheets while passing
therethrough, and also may be worked with slitting. The upper and lower roll shafts
33 are held rotatably by using the bearings 35 and operatively in such a manner that
the cardboard sheet may be carried in a sandwiching manner by the engagement of the
sandwich roll elements 34, 34, and on one sides of these roll shafts 33 there are
fitted the gears 36 meshing with each other at the ratio of 1:1. On the extension
of one end of the roll shaft 33 there is installed a pulley, which is connected operatively
to another pulley on the DC motor 37 by using a V-shaped belt or the like; with this
arrangement, any change in the rotating speed of the sandwich roll elements 34, 34
may be accomplished by detecting the current edge position of a cardboard sheet to
be fed at or near the central portion of the upper and lower sandwich roll elements
34, 34, and by feeding thus-obtained signal into the DC motor 37, and thus changing
the rotating speed of the DC motor 37, accordingly.
[0010] Next, referring to the operation of the delivery conveyor 10 according to FIG. 5
which shows the state before the died cardboard 11' reaches the sandwich roll elements
34, the sheets ①, ②; ③, ④; ⑤, ⑥ depicts respectively the state of sheets fed from
the blank cardboard supply station 1, or in other words the state that these sheets
are disposed in a discrete relationship with each other. The spaces between the sheets
② and ③, and between @ and 6 represent a difference in the circumferential length
of the die cut cylinder 8 and the overall extension of the died sheets ① and ②. △ℓ
represents a small gap produced between each of the adjacent died sheets. The rotating
speed (the circumferential speed of the roll surface) V
3 of the sandwich roll element 34 (or the rotating speed of the DC motor 37), which
may be known by detecting the timing that the edge of the died cardboard 11' passes
by using the photoelectric tube 32, is changed as shown in the timing chart of FIG.
7. FIG. 7 shows the relationship between the timing of detecting the passage of the
died cardboard 11' by the photoelectric tube 32 (that is, the case that the gap between
the adjacent sheets is detected is defined to be the light receiving state, while
the case that a sheet is detected being defined to be the light blocking state.) and
the current rotating speed of the sandwich roll element 34. The sandwich roll element
34 is driven at the rate V
3 = V
2 while the sheet ① passes the photoelectric tube 32, and then, upon the blocking of
the photoelectric tube 32 by the leading edge of the sheet ②, is reduced down to V
3 = V
i , or the level of 2ℓ/L x V
2 . Thereafter, the photoelectric tube 32 functions to detect the gap between the sheets
② and ③, and the sandwich roll element 34 are again driven with an increased speed
of V
3 = V
2 . With the repetition of such operation, a series of died cardboard 11' may be delivered
on the stacker-conveyor 12 at a generally equal interval of △ℓ' one after another,
accordingly. The driving speed of the upper and lower sandwich roll elements 34, 34
is increased or reduced with the same speed rate in proportion to the rotating speed
V
2 of the die cut cylinder 8.
[0011] FIG. 9 shows another embodiment of the invention wherein the rotating speed of the
sandwich roll element 34 is changed by shifting a first electromagnetic clutch 40,
etc. incorporated or installed otherwise in a motor 38 and a pulley and a second electromagnetic
clutch 41, etc. incorporated or installed otherwise in a second motor 39 and a pulley,
with which embodiment there is attainable an equivalent effect and function to that
of the previous embodiment.
[0012] FIG. 10 shows a further embodiment of the invention, wherein the sandwich roll elements
and the speed change device are replaced with a conveyor belt 44, a conveyor roll
45 and a motor 42, with which there is also attainable an equivalent effect and function
to that of the embodiment described hereinbefore.