Note: Descriptions are shown in the official language in which they were submitted.
6~
1 APP4~ATUS FOR ~ONV~YING A STRIP O~ RAW
M.4TERI~L IN A BAG PRODUCIN~ MACHINE
BACKGROU~ OF THE INVENTIGN
FIELD OF THE INVENTION
The present in~ention relates to an apparatus
-Eor conveying a strip of raw material for
producing bags in a bag producing machine,and
more particularly to improvemen-t of cr relating
to an apparatus for intermi-ttently conveying a
~0 strip o~ film ~inclusive ~lattened tube) made of
thermoplas-tic synthetie resin such as polyethylene,
polypropylene or the like so as to conduct various
s-~eps of processin~ such as bag forming,
perforating, punching, cutting, packing and others
while the s-trip is kep-t i.~lovable~
DESCRIPTION O~ THE PRIOR ART
A hitherto known processing machine such as
bag producing machine of the above-mentioned type
is construc-ted such tha-t a strip of raw material
such as ~ilm, flattened tube or the like held on
a so-oalled roll stand is unreeled by means o~
an opposing pair of continuously operating
conveyors ~ineluding rollers),and it is then
con~eyed by means of an opposing pair of
æ
2~
1 intermittently operating conveyors (including
rollers~ in such a manner that part of the strip
îs loosened in the elliptical form in th~ strip
loosening section disposed between both the con-
veyors. The looserled part of the strip is
displaceably supported on an inclined conveyor
of which upstream side end assumes an elevated
position and downstream side end does a descended
position,as disclosed in Japanese Patent NO.
1,114~094 (Patent Publication NO. 3581/82).
In the first mentionecl case where a 3.oosened
part o the strip is not ~upported during its
conveyance~there is tendenc:y of causing the strip
to float up in the loosening section due to
impulsive conveyance carried out by means o:E the
intermittently operating conveyors disposed at
the downstream side of the processing machineO
Especially when a strip of film has a thickness
less than 15 microns, the above-mentioned
tendency bec~mes remaxkable. On the other hand,
in the last mentioned case where a loosened part of
the strip is supported on th- inclined surface
of the belt conveyor,there is seen less tendency
~f causing the strip to float up. Particularly
~5 in case where static electricity is generated
-- 2 --
.. . .
1 due -to friction between the inclined belt conveyor
and ~he strip and they are electrified in different
polarity,the aforesaid phenomenon of floating-up
is completely inhibited owing to attractive
function given by static electricity.
However, it has been found with respect to the
conventional apparatus that the inclined belt
conveyor and the strip are electrified in the same
polarity in dependence on correlation among material of
1~ the str~p,material employed for ink printed on
strip and material of inclined belt conveyor,
resulting in the s-trip failing to come in contact
with the conveyance surface of the inclined belt
conveyor. Thus, the s~rip is caused to float up
above the inclined bel-t conveyor. In an extreme
case the strip is turned over or wrinkled and
therefore any subsequent step of processing cannot
be performed.
To obviate the foregoing drawback of the
conventional apparatus~the applicant developed
an apparatus for conveying a strip of raw material
for producing bags with the aid of an inclined
belt conveyor which serves as attractive means
(as illustrated in Fig. 83 and filed an application
for registration of utility model under Japanese
~Z~ 6
1 Utility Model Application N0. 170343/82. However,
it has been found that the newly developed
apparatus has still the following drawbacks.
As is apparent from Fig. 89 a strip of raw
material F is intermittently co~eyed in the
working area be-tween the processing section A
disposed at the downstream side of a bag pro~ucing
machine and the inclined belt conveyor ~ as an
opposing pair of intermittently opera-ting conveyors
~ are rotated intermittently~ while an amoun-t of
loosening of the strip increases or decrease 9 .
Due to the ~aot that no guide roller :LS disposed
at the position located in the proxim^lty of the
upper surface of the inclined belt co~veyor,it
lS happens that the strip is li-E-ted up in the
direction ~t a right angle to the wor'~îng surface
o~ the inclined belt conveyor when an amount of
loosening o~ the strip varies9 causing the latter
to flutter under the influenc0 of air resistar,ce.
This leads to occurence o~ wrinkles over the
surface of the strip and thereby the la-tter is
brought în a snaking motion.~urther9 the working -
area on the inclined ~elt conveyor where -the s-trip
is attrac-ted varies as an amount of loosening of
-the strip varies. ~hus9 a larger volume o* air
-- 4 --
. . .
1 permeates through the non-working area o~ the
inclined belt conveyor where no strip is heldO
This means that -the strip fails to be attracted
onto the inclined belt conveyor under constant
attractive force at a~l time and therefore it i5
di.fficult to con~ey the strip in the stable
posture.
Sl~ ~Y O~ THE INVEN~ION
Thus7 -the presen~ invention has been made
l o with the -foregoing baokground in mind.
It is a major object c)f the present in~n-tion
to provide an improved apparatus for conveying a
strip of raw materia~ for producing bags in a bag
producing machine which assures tha~ -the ~-trip is
oonveyed wi-thout oc~urence o~ flutterin~ and snake
movement o~ the strip during its conveyance while
i~ is attracted onto the inclinea belt conveyor .
over -the subs~antially whole surface thereof at
all times.
It is another object of the present in~entio~
to provide an improved apparatus for conveying a
strip of raw material for producing bags in a bag
producing machine of which improvement is achieved
by sïmple arrangemen~
_
"~
1 It is another object of the present invention
-to provide an improved apparatus for conveying a
strip of raw material for producing bags in a bag
producing machine of which improvement brings very little
i~crease in cost of the bag producing machine.
To accomplish the above objects,there is
proposed in accordznce with -the pres~nt invention
an im~roved apparatus ~or conveying a strip o~
raw material for producin~ bags in a bag producing
mach-ine o f the type including an o~osing pair of
contirluously operating conveyors disposed at the
ups~ream side) an opposing pair of intermittentl~
operating conveyors disposed at the downstream
side of the bag proclucing machine,and.an inclined
belt conveyor for displaceably holding the
loosened part of the strin on the inclined upper
surface thereo~, the inclined belt conveyor
being disposed in the in-termediate working area
between both the upstream and downstream conveyors
in such a manner that i-ts upstream end part
assumes an elevated position and its downstream
end part has a descended position, so that the
strip is conveyed throu2h the bag producing machine,
~herein the improvement comprises the inclined
25 . belt conveyor including a belt made of air
~z~
1 permeable material; a suction device disposed
below the inclined belt conveyor to suck air
throvgh ~he air ~ermeable belt and a large number
of holes or slits f`ormed thereon,so as to allow
the strip to be attracted onto the workin.g surface
of the inclined belt conveyor under the influ&nce
of reduced pressure, the suction device being in
communica-tion with a vacuum pump; and a ~uide
roller for guidin~ movement of the turnover part
. 10 o~ the strip towar~ the do~stream conveyors, the
guide roller being located above the inclined belt
conveyor a~ the position l.ocated in -the proxi~ity
of the upper surface of the latter in the
working area extending from the middle ~art to
the ups~e~m ~nd part o-E th.e belt con~eyor ~hile
i-ts axis assuming -the horizon~al posture.
In a ty~ical embodiment of the învention,
the inclined be~t con~eyor includes a plurality
of endless plain bel~s extPnding in parallel with
one ano~her in the direction of conveyance.
The suction device i~ preferably designed
in the form of ~ flat box of which width is
dimensioned same às the working width of the
inclined belt conveyor~
The suction device may be cons~rueted by a
~ 7 --
,, `'' , , .
~Z~6~ 6
1 plurality of ~erforated cylindrical rollers ext-
endin~ at a righ-t angle relative to the direction
o~ conve,~ance of the inclined belt conveyor.
Further, the suction device ma~ be constructed
by a ~lurality of tubes with a large number of
holes or tubes -formed thereon, -the tubes extending
în the direc~ion OL conveyance ol tne inclined
belt conveyor.
The air permeable belt on the inclined belt
conveyor is made oE air per~eable ma~erial
selected preIerably from a group comprising cloth~
~et, mul-ti-string and porous syn~hetic rubber~
Other objec-ts, ~eatures and advantages of
,the present invention will become more clearly
apparent from reading of the ~ollowin~ descrip~t-
ion which has been prepared in conjunction o~
the accom~anying drawings~
~RIEF DESCRIPTION OF THE DP.A~'IINGS
The accom~anying drawings will be briafly
2Q described below.
Fig. 1 is a side ~iew of a bag producing
machine with an ap~aratus of'the invention
incorpora~ed therein, schematically illus-trating
how the apparatus is arranged for the machineO
26
1 Fig. 2 is a sid~ view of the inclined belt
conveyor constituting essential components of the
apparatus, schematically illustrating how it is
constructed in association with a vacuum system.
Fig. 3 is a perspec~ive view o~ the inclin~d
belt conveyor, of which part is cut away for the purpose
of illustration of a suction box.
Fig. 4 is a fragmental ver-tical sectional view of
the inclined belt conveyor including a suction device,
which comprises a plurality of perforated cylindrical
rollers.
Fig~ 5 is a vertical sectional. front view of the
cylindrical roller, taken at line 5 - 5 in Fig. 4.
Fig. 6 is a perspective view of the inclined helt
conveyor showing a suction device comprising a
plurality of perEorated tubes.
Fig. 7 is a perspective view of an inclined belt
conveyor including two lines of endless belts
extending in parallel with one another, and
20 Fig. 8 is a side vi.ew of a bag producing machine
with a conventional apparatus incorporated therein,
schematicall~ illustrating how the apparatus is
arranged for the machine~
1'.~
1 DESCRI TI~N OF T~E PREF~RRE~ Er~B~DII~ENTS
Now, the present invention will be described in
a greater detail hereunder with reference to the
accom~anying drawings which illustrate preferred
embodiments thereof.
In ~igs. 1 to 7 re~erence numeral 10 designates
a roll stand for rota-tably holding a roll of raw
material. A strip o~ raw material ~ for producing
bags is normally wound on a core tube ln the form of
a roll through which a support shaft 11 is extended.
A roll of raw material is then rotatably held on the
roll stand 10. In case whare the roll has no ~u~port
shaft, it is placed on an uncoiling machine so that
a strip of raw ma-terial is uncoilsd therefrom~
A strip of raw material F uncoiled from the roll
stand 10 is ~irst delivereld to an oppos3ng pair o~
continuously operating con-~eyors 12 (including rollers3
which are disposed at ~he working area located
upstream of the bag producing machine. After leaving
~0 the conveyors 12, the s-trip moves through a proc~ssing
SectiQn 13 such as welding apparatus,and it is then
delivered to an opposing pair o~ intermittently
operating conveyors 14 ~including rollers) which are
disposed at the working area located downstream of
~he bag produoing maohine~ An inclined belt conveyor
-- 10 --
. .
1 15 is arranged below the loosening section for a
strip of raw material F located between the conveyors
12 and the processing section 13,in such a manner that its
upstream end assumes the elevated position and its
downstream end has the descended position. Woxking
speed of the inclined belt conveyor 15 is determined to
be 10 to 50 % higher than that of the conv~yors 12.
The above-described arrangement of the bag
producing machine is substantially same as that of
the conventional machine. Essentially, the pres~nt
invention consists in that the belt conveyor 15
includes a belt 16 made of air permeable material.
Roughly woven cloth is typically employable for
the belt 16. Alternatively, net, p~ain rubber belt
with a large number of small holes distributed over
the whole surface,and a numlber of strings or narrow
hands extending in the parallel relation may be
employed.
As is apparent from the drawings, a suction
device comprising a single suction box 18a or a
plurality of suction tubes 18b with a large number Gf
suction holes or slits 17 formed thereon is arranged
below the working area of the belt 16 constituting
the inclined belt conveyor 15. The suction box 18a
or the suction tubes 18b are conne~ted to a va~uum
pump lgo
~f~l6~
1 When plural strips of raw material F are used,
it is preferable that -the same number of belts 16 as -
at o:E the strips -are extended between a pair o~
rolls 15a and 15b eonstituting the belt conveyor 15
in the parallel relation, each of the belts 16
having the same width as that o~ strips and being
formed with a large ~umber of equally spaced suetion
holes 16a along both the side edges,which are
located in vertical align~ent with sueti.on holes or
slits 17 on the suction box 18a or the suction
tube~ 18b.
In a pre~erred embodiment as illustrated in
Fig. 3,the suction box 18a is designed irl the ~orm
o~ a ~lat box having the a~ubstantially same wid*h
as that nf the inclined bellt conveyor 15. In an~ther
embo~iment as illustrated in Figs. 4 and 5,the
suction tubes 18b are repl.aced with a plurality of
per~ora~ed rollers 18c of which axes extend in the
hori~on-tal direction at a right a~gle relative to
the direction o~ conveyance of the inclined belt
conveyor 15. The perforated rollers 18c are adapted
to rotate at the same peripheral speed as the
travelling speed of the belt 16,and each of ~hem is
fitted with an inner tube 21 with an axially
extending slit 20 ~ormed at the upper part thereof,
6~
1 the inner tube 21 being fixedly seeured to a frame
structure of -the machine. Thus, suction is effected
only from the upper part of each of the perfora~ed
rollers 18c. In -the ~ig,5 drawiny reference numeral 23
designates a driving gear ~including a sprocket
gear) fixedly mounted on both the end parts o~ the
perfor2ted roller 18c.
Fig~ 6 illustrates a plurality of suction tubes
18b ex-tending in the direction of convey~nce of the
inc]lined belt conveyor 15~ each o~ the suction tubes
18b being formed with a ~umber of suction holes 17
at the upper part thereof. The suction holes 17
may be replaced with a single slit extending in th~
longitudinal direction.
Referri.ng to Figs. 1 and 2 again, reference
numeral 24 designates a guide roller disposed in the
proximi-ty of the upper surface of the belt 16
constituting the inclined belt conveyor 15~ The
horizontally extending axis of the ~uide roller ?4
is 7Ocated at the position in the area extending
between the middle part and ths upper e~d part of
the belt 160 The guide roller 24 ser~-es to guide
mo~ement o~ the strip F through a zigzag passage 25
in cooperation with other guide rollers after the
ætrip F is turned rearwardly at the turnover point Fo
- 13 -
.. ~
~L2~6i~2~i
1 loca-~ at the downstream end of the belt conveyor 15.
The strip F is then del.ivered to the processing section
13 and after completion of the intended proce~sing, it
moves to the intermittently operating conveyors 14.
In the Figs. 1 and 2 drawings, reference numeral 26
designates a sensor for detecting a turnover length o
the strip F. When it is detected by the sensor 26 that the
turnover length of strip F is shorter than a predetermined
length, the continuously operating conveyors 12 at the
upstream side of the machine are caused to rotate at a
higher rotational speed. An optical sensor 26 is
.preferably employable. Alternatively, an inexpensive
microswitch may be used for the sensor 26
Next, operation of the conveyance apparat.us of
the invention as constructed in the above~described
manner will be des~ribed below.
A strip of raw material F for produclng bags
loosened between both the conv~yoxs 12 and 14 is
attracted to th~ substantially whole area o~ the
inclined belt conveyor 15 and it is then turned
rearwardly at the turn point Fo at the downstream
end of the latter. Thereafter, it is processed in the
form of bags while it is intermittently delivered
to the conveyors 14 with the aid of the guide
~ 14 -
~ ,, ~ . .
1 rol]er 24.
When it is detected by the sensor 26 that the
turnover length of str~p becomes shorter than the
predetermined one during intermittent conveyance
of the strip, the conveyors 12 are caused to rotate
at a higher rotational speed so that a turnover
length of strip increases. It should be noted that
a strip of raw material is always attracted to the
whole area o~ the inclined bel~ conveyor 15 under
the influence o reduced pressure in the suction
box while the apparatus is operated.
As will be readily ~mderstood rom -the above
description, arrangement of the guide roller 24
causes increase or decrease in ~oosening of the
strip F, that is, increase or dec~ease in turnover
length of the same to occu;r as a result of change
in length of the strip which is attracted to the
upper surface of the inclined belt conveyor 15,as
well as length o~ the strip which moves ahead
after completion of turnover. Thus, an amount of
loosening o~ strip changes only due to movement
of the strip in the longitudinal direction.
This means that a proper amount of loosening
of strip can be obtained without any occurence
of air resistance, fluttering of strip
l during intermittent conveyance, snaking mo-tion
and excessive stre-tching of strip. ~urther,
there is no fear of causing the strip F -to ~loat
up above the inclined belt convey~r 15/ turn over
and wrinkle e~en when i-t i3 impulsively pulled by
the intermit-tently operating conveyors 14. It
sh~uld be added tha~ ~ulling operation of the
con~eyors 14 is accompanied by little resistance.
Thus, the apparatus of -the invention assures
tha.t a str.ip of very thin film is conveyed :
reliably a-S all tim~ irres~ective o~ material of
the film,and conveyance is e~ected at any inelin~
ation angle of the inclined belt conveyor 15
owing to the ~act -that the strip F is attracted
to -the latter under the influence of reduced
pressure in the suctionbo~ .l8a. Another advan-tageous
feature of the invention is that -the apparatus
can be installed on a reduced area on the floor~
Nex-t, characterizing features of the apparatus
of the inven-tion will be summari3ed below.
In case where the suc-tion device co~prises a
single *la-t suction box 18a as illustrated in Fi~s~
2 and 3,the apparatus of -the invention is simple
in s~ruc-tu~e and has no trouble in operation.
In case where the suction de~ice comprises a
-- 1~
1 plurality of perforated tubes adapted to rotate in the
same direc-tion as that of movement of the belt 16, as
illustrated in Figs. 4 and 5, the belt 16 is brought in
rolling contact with the suction tubes 18b and thereby no
frictional resistance appears. With respect *o the per-
forated tubes 18c, the inner tubes 21 on which they are
rotatably held are formed with a slit 20 respectively and
therefore suction is effected within the limited area
where each of the slits 21 comes in contact with the
belt 16~ resulting in excellent suction efficiency
being assured.
In the embodiment as illustrated in Fig. 6
a plurality of suction tubes 18b serving as a
suction device are arranged in the direction ~f
conveyance. In the illustrated case thexe are provided
4 to 6 suction tubes and therefore little contact
resistance appears. ~hus, the apparatus is simple
in st.ructure and has no troubl~3 in operation. When
6 or 12 suction tubes 18b are used, two or three
strips of raw material F are preferably caused to
extend in the parallel relation, so as to allow the
number of suction tubes 18b per one strip of raw
material F to be same as that of the foregoing case. As a
:, . . .
~2~
1 result -there is no fear of causing a soecific
strip of raw material F to be attracted very
intensively.
','~en eacn o~ the belts 16 are formed with
a number of small ho~es 16a along both the side
edges in such a manner that they are located in
vertic21 ali~rmen~ h suction holes or sli-t~
17 on each of the suction tubes l~b as illustra-ted
in Fig. 7, a ~lural stri~s of raw material F
c~n be conve~ed in the stable ~osture while
both ~he side edges o* eac'h of the strips are
a~tracted on~o the outer surface of the belts
16.
'.'~ile the ~resent inven-tion has been described
~bove with resp0ct to a few ~referred embodiments,
i~ should o-E cource be understood that it should
not be'limited only to them and various changes
or modifications may be made in a suitable
manner withou~ any departure from the spirit and
scope o~ the in~lention~
