[0001] The present invention relates to a machine intended for the automated manufacture
of filter bags filled with infusionable substances, for example tea, herbal powders
and similar products.
[0002] The adoption of filter bags as a means of preparing individual beverages by infusion,
both in the home and in catering, is now general practice the world over: it is indeed
by virtue of their simplicity and ease of use that filter bags have become so widely
accepted.
[0003] In the light of this increased popularity, attempts naturally have been made to maximize
the appeal of the single bag, especially by those who distribute the product on the
market; one has seen improvements in retention of the particulate substance, in the
rate of interaction with liquids during the time allowed for infusion, in shelf life,
in ease of final packaging, and so forth...
[0004] For example, one has seen a change from the original bag, appearing as a single envelope
with a finger tab label or tag attached by a thread, to the now familiar pattern incorporating
two envelopes (also with thread and finger tab label, and in some cases individually
wrapped), which is fashioned from a tubular blank of filter paper filled with two
distinct measures of the substance and folded double (thereby obtaining a more effective
release of the substance due to the larger surface area in contact with the liquid),
also to the simpler type of bag consisting in a plain rectangular or circular envelope
with no thread or label, which is packed generally in boxes containing one or more
rows and without any additional wrapping.
[0005] Reference is made in the present specification to a machine for the manufacture of
this latter type of filter bag, and in particular to individual or one-cup bags consisting
in single envelopes of rectangular or circular outline, fashioned generally in pairs
side by side from a pair of plain filter paper strips placed one against another and
sealed along the edges, each containing a measure of the infusionable substance.
[0006] In their current form, automatic machines of the type in question (see also Italian
patent n° 1 199 414 in the name of the present applicant) comprise a series of stations
arranged along a substantially horizontal pass line, by which single bags of the infusionable
substance are fashioned and made ready for packaging into boxes.
[0007] At a decoiling station located first in sequence along the pass line, a continuous
strip of filter paper is drawn from a roll and divided longitudinally into two halves;
the first half is directed beneath a station from which measures of the infusionable
substance are dispensed singly, or alternatively in pairs arranged two abreast, whilst
the second half is made to by-pass the dispensing station and then assume a position
over the first half, covering the single or paired measures of the substance already
deposited on the paper.
[0008] The station next in sequence, or rather positioned following the dispenser along
the pass line, comprises means by which to heat seal the external border of the two
joined halves and, where the bags are fashioned in pairs, also the mid-line dividing
the measures of the infusionable substance lying two abreast on the first half; such
heat seal means will consist, typically, in a pair of rollers counter-rotating about
respective horizontal axes and positioned one directly above the other.
[0009] The continuous strip of bags fashioned in this way is advanced along a table toward
a station at which it is severed longitudinally by means of a special cutter, and
thereafter through a further station at which it is divided transversely by a second
rotary cutter into a plurality of single bags. The discrete bags are then stacked
in pairs at a station immediately beyond the transverse cutting station. More exactly,
the bags are stacked in a given predeterminable number internally of a vertical duct,
then, after descending vertically, released onto a moving horizontal surface and conveyed
toward subsequent stations either incorporated into or separate from the machine,
by which the end product is packed into boxes.
[0010] Each machine unit operating at the various stations mentioned above (dispenser, heat
seal rollers, cutters and stackers) is set in motion by a drive system which normally
will be centralized, and connected with the single units by way of mechanical transmission
links comprising gears, chains or belts; the drive ratios and proportions of these
are selected according to the output required from each unit, so as to maintain the
production of bags steady and correct, or according to the dimensions of the end product.
In other words, the machine operates to certain key parameters, namely the size of
the filter bag, which if changed will require adaptation or replacement of the heat
seal rollers and the dispenser, and the final packaging format, i.e. the number of
bags or pairs of bags destined to make up one box.
[0011] Machines structured after this fashion by now have a long pedigree and are able to
combine high output per unit of time with an appreciable guarantee of quality in respect
of the finished product, but tend at the same time to betray a certain lack of "flexibility"
as regards the material requirements of the manufacturer, typically the need to change
quickly to a different packaging format (number of bags per box) for a given market,
and possibly to make minor alterations to the size and/or shape of the bag. To change
the setup of such a machine, it becomes necessary on each occasion to alter the drive
ratio for each one of the stations affected by the change, making manual adjustments
to the transmission link between the drive system and the machine unit and thus changing
the positions occupied by the units at the start of the cycle. This is done for example
with the aid of a circular graduated scale fitted to each gear, which can be used
to set a new "zero" or starting point for the unit, or perhaps by changing the transmission
link wholly or in part.
[0012] However, this operation inevitably dictates a stoppage that may keep the machine
idle for some considerable time and in consequence can have a negative impact on its
overall productivity each time the need for such a changeover happens to arise.
[0013] Accordingly, the object of the invention is to provide a machine for the automated
manufacture of filter bags containing infusionable substances, designed in such a
way that the output per unit of time and the ultimate packaging format can be changed
automatically without the machine itself having to stand still for prolonged periods
and with no need for mechanical adjustments to made directly to any of its component
parts, beyond the obvious replacement of machine units or assemblies directly influenced
by the shape and size of the bag, namely the dispenser, heat seal rollers etc.; instead,
the angular position of the shafts driving the various machine units is controlled
directly in such a manner that the motors can be retimed in a few moments and the
operating cycle of the machine restarted without delay.
[0014] The invention will now be described in detail, by way of example, with the aid of
the accompanying drawings, in which:
- fig 1 illustrates a machine according to the present invention for the automated manufacture
of filter bags containing infusionable substances, seen in a general schematic elevation;
- fig 2 illustrates the succession of steps involved in fashioning a filter bag using
the machine of fig 1, starting from a strip of filter paper and terminating with the
emergence of a single bag, viewed partly in plan and partly in a side elevation;
- fig 3 is a block diagram of the elements making up the control system to which the
drives of the machine disclosed are interlocked;
- fig 4 is an enlarged detail of the machine shown in fig 1, illustrating the manner
in which longitudinal and transverse cutters and a stacking station are connected
to respective drives, viewed schematically and in elevation with certain parts omitted
better to reveal others.
[0015] As discernible from the accompanying drawings, and in particular fig 2, the present
invention relates to an automatic machine for the continuous production of filter
bags 1 containing an infusionable substance (typically tea leaves, camomile flowers,
etc.).
[0016] The bag 1 (see fig 2) is of the type fashioned from two breasted strips 2 and 3 of
filter paper enveloping a measure 4 of the substance and heat sealed together at the
edges. Fig 2 shows a continuous strip of such bags 1 which in the particular example
illustrated are generated in pairs two abreast by the various units of the machine
for reasons concerned purely with output, albeit the principle clearly would stay
the same were the bags to be generated in a single file utilizing two narrower strips:
in short, the inventive concept underlying the machine remains unaffected.
[0017] The machine in question incorporates a succession of stations (see fig 1) arranged
along a horizontal pass line indicated by the arrow denoted A.
[0018] Located first in sequence along the pass line A is a station 5 at which a continuous
film F of filter paper is decoiled from a bulk roll 6 secured to a freely revolving
pivot 37; the film can be fed initially in one piece and then divided as in the example
of the drawings, or alternatively, two separate rolls might be utilized.
[0019] The decoiling film F is directed by way of transfer rollers 38 toward longitudinal
cutting means 7, shown in the drawings as a circular cutter 7c anchored to a fixed
structure 36 of the machine, and divided into two films F2 and F3 of identical width
that will be heat sealed together ultimately to fashion the bag 1 (as discernible
from fig 2).
[0020] Thereafter, the first strip 2 or first film F2 is directed into a second station
8 from which measures 4 of the infusionable substance are dispensed through the agency
of metering means 9 embodied as a revolving drum 39 and set in motion by a relative
motor 8m; the measures 4 are deposited pair by pair in succession on the advancing
strip 2, two abreast (see fig 2). The drum 39 in turn receives the substance from
a hopper unit 40 (conventional in embodiment and therefore illustrated only in part)
mounted above and connected to the drum.
[0021] Following the longitudinal cut, the second strip 3 or second film F3 advances toward
the second station 8, which it joins at a given point beyond the revolving drum 39:
in practice the second strip 3 is caused to by-pass the second station 8, being diverted
instead through transfer means 10 afforded by a set of idle rollers 10r positioned
above the drum 39, thereafter descending and covering the first strip 2 with the measures
4 already in place.
[0022] The two joined strips 2 and 3 advance toward a third station 11 at which they are
heat sealed together in the longitudinal and transverse directions. This third station
comprises a pair of contrarotating rollers 11a and 11b set in motion by a drive comprising
a single motor 11m and a timing belt 41; the two rollers 11a and 11b present a contoured
and heated contact surface (conventional in embodiment and therefore indicated only
in part) such as will seal a peripheral area of the strips 2 and 3 circumscribing
each measure 4 (the outline will be selected on the basis of packaging and marketing
requirements) and thus generate a plurality of single bags 1, still united in a continuous
strip and advancing in pairs two abreast (as indicated to advantage in fig 2).
[0023] Referring to fig 1, the two contrarotating rollers 11a and 11b are mounted overhung,
each rotatable about a pivot coinciding with the relative horizontal axis of rotation,
denoted 11ay and 11by. The pivots 11ay and 11by are associated permanently, to the
front of the machine, with relative moving arms 42 associated in their turn at the
rear of the machine with respective ends of a pair of rods 25 and 26; the two rods
combine to create a toggle mechanism 27, connected pivotably to the end of a pneumatic
actuator 28 (a cylinder in practice) disposed horizontally and anchored to the aforementioned
fixed structure 36, by which the two rollers 11a and 11b can be drawn together and
spread apart respectively at the start of a cycle and when the cycle is interrupted,
in response to control media that will be described more fully in due course.
[0024] Continuing along the pass line beyond the heat seal rollers 11a and 11b, the advancing
strip of bags 1 is cut longitudinally at a sixth station 12 through the agency of
a second circular cutter 13 and divided into two halves, with the result that two
parallel files of bags 1 are generated (the numbering of the stations is derived from
the chronology of the appended claims, hence the slight discrepancy in terms of descriptive
sequence when reading the specification).
[0025] More exactly, the second longitudinal cutter 13 (see figs 1 and 4) is positioned
beneath the pass line A followed by the continuous strip of bags 1, whilst the station
12 also comprises a reaction wheel 29 located above the cutter 13 and the strip, mounted
rotatably to a block 30 secured to the fixed structure 36 of the machine. 29a denotes
a pair of pinch wheels positioned immediately preceding the cutter 13.
[0026] The strip of bags 1 (not separated longitudinally as yet) can be restrained by means
of a clamp element 31 located between the two wheels 29 and 29a and anchored to the
selfsame block 30, of which the operative end portion is capable of movement vertically
between an inactive raised position, distanced from the strip in such a manner as
to allow its advance, and an active lowered position of stable contact in which the
strip is prevented both from advancing any further and from returning toward the third
station 11 in the event of the operating cycle being interrupted.
[0027] Once beyond the sixth station 12, the two continuous strips of bags 1 are severed
transversely at a fourth station 14 comprising a first cutter 15, consisting in a
roller 15r fitted with a double edged blade, in such a way as to generate the discrete
bags (see fig 2); the cutter 15 is driven by a relative motor 14m, which also transmits
rotation to the second cutter 13 by way of a further timing belt 14c.
[0028] The cut bags 1 are collected and stacked at a fifth station 16 through the agency
of means 17 by which the stacks are formed according to subsequent packaging requirements
and in predetermined number.
[0029] More exactly, the means 17 in question are embodied as a vertical duct 32 with open
top and bottom ends by which the single bags 1 are accommodated two abreast, one on
top of another (creating a pair of stacks P1 and P2 each composed of single bags),
and supported initially on two bearers 48 before dropping down onto a movable platform
denoted 33.
[0030] It is by these two bearers 48, disposed one on either side of the duct 32, that the
bags 1 are divided and sorted into the number per relative stack P1 and P2 required
to make up the final package. The bearers 48 are essentially C-shaped, and positioned
facing one another with the active top finger ends insertable through respective slots
afforded by the walls of the duct 32; the bottom ends are pivotably associated with
a support 49 which is secured in its turn to a belt 50 driven by a further motor 48m,
in such a way that the bearers 48 can be set in motion along the duct 32.
[0031] The bearers 48 are designed to spread apart and draw together respectively into open
and closed positions, utilizing the pivotable association mentioned above (see fig
4): anchored by their bottom ends to the piston rod 48a of a vertically disposed actuator
48p associated rigidly with the support 49, the bearers 48 can be distanced from one
another by the actuator 48p (as illustrated in fig 4) when the stack of bags 1 is
due to drop onto the platform 33, then drawn together to create a temporary second
platform above and thus separate the stacked bags 1, already deposited on the movable
platform 33 and descending toward the bottom of the duct 32, from the cut bags continuing
to enter above and destined to make up the next package.
[0032] The platform 33 is capable of ascending and descending movement within the duct 32,
its operation timed in relation to the opening and closing movement of the bearers
48 in such a way that bags 1 can be assembled in the numbers required for subsequent
packaging steps at other stations.
[0033] To obtain this same ascending and descending movement, the platform 33 is rigidly
associated with a support element 43 capable of sliding along a rod 44 anchored to
the fixed structure 36 of the machine; the support element 43 is set in motion by
way of a lever arm 45 pivotably associated at one end with the element and at the
opposite end with the fixed structure 36, and coupled also to a crank mechanism comprising
a rod 46 of which one is anchored to a slot 45a afforded by the arm 45 and the remaining
end to a wheel 47 driven by a motor denoted 16m. In this way, the arm 45 is invested
with alternating motion and the platform 33 supporting the bags 1 will rise and fall
with each revolution of the power driven wheel 47.
[0034] Each time the movable platform 33 reaches its lower travel limit, a diverter 51 located
at the bottom of the duct 32 directs the two stacks P1 and P2 of bags 1 in a horizontal
direction toward the aforementioned packaging stations (not illustrated in the drawings,
being conventional in embodiment and no more than incidental to the present invention).
[0035] The diverter 51 is set in motion by a rod 52 connected via a transmission link, denoted
53 in its entirety, to a cam 47c which is also connected to the motor 16m driving
the platform in such a way that the diverter and platform 51 and 33 are permanently
synchronized.
[0036] Located at the top end of the stacking station 16 is an arm 34 by which the bags
1 are directed forcibly into the duct 32; disposed transversely to the duct and anchored
by way of a fulcrum pivot 35 to the fixed structure 36 of the machine, the arm 34
is caused to alternate in time with the movements of the remaining stations, being
connected likewise to the motor 14m driving the first cutter 15, and to move in a
vertical direction V in such a way that its free end 34a will impinge firmly on the
bags 1 advancing from the first cutter 15, thus favouring and ensuring their correct
entry into the duct 32.
[0037] The main machine units at the majority of the stations described thus far, and in
particular the dispensing station 8, the heat seal station 11, the transverse cutting
station 14 and the stacking station 16, are driven by dedicated motors, i.e. 8m, 11m,
14m and 16m respectively, also 48m in the case of the bearers 48; each motor operates
both independently of and in timed coordination with the remainder, providing e.m.f.
for a respective machine axis 8x, 11x, 14x, 16x and 48x of which the angular position
is controlled electrically.
[0038] In other words, each single axis 8x, 11x, 14x, 16x and 48x performing a given work
cycle in the machine is controlled independently in respect of predetermined operating
parameters (described in due course) by way of elements connected directly and indirectly
to the movement of the selfsame axis.
[0039] More exactly, one of these electrically controlled axes, and in particular the axis
14x driving the first or transverse cutter 15, provides the master axis to which all
remaining axes are referred: in this way, it becomes possible to establish operating
parameters for the start of the cycle or for changing these selfsame parameters during
the cycle.
[0040] All axes of the machine, the term "axis" signifying the electric motor together with
the unit 8g, 11g, 14g, 16g and 48g by which its operation is controlled (as indicated
in the diagram of fig 3) are interlocked to a monitoring and control unit 21 (e.g.
utilizing printed circuit modules) such as will keep track of their angular positions
one relative to another on the basis of variable operating parameters, i.e. the type
of cycle adopted in manufacture of the filter bags 1, the number of bags per package,
also the pattern and size of the single bag.
[0041] To this end, still referring to fig 3, each axis 8x, 11x, 14x, 16x and 48x is equipped
with respective first means 18 (typically conventional encoders keyed directly to
the relative motor shaft) by which to monitor the position of the axis both as an
angular value and in relation to the corresponding station 8, 11, 14, 16 and 48, also
second means 19 (typically conventional proximity sensors connected indirectly to
the relative motor shaft) by which to determine the absolute position in space of
the machine components associated with the single axes 8x, 11x, 14x, 16x and 48x,
i.e. the drum 39, heat seal rollers 11a and 11b, first cutter 15, platform 33 and
bearers 48.
[0042] In short, each machine component is monitored in terms both of its expected position
at a given moment in the context of the operating cycle, and of its prescribed absolute
position in the light of the aforementioned operating parameters, which are pre-programmable
by way of the monitoring and control unit 21.
[0043] As discernible from fig 3, the monitoring and control unit 21 might comprise one
circuit module 22 for each one of the axes 8x, 11x, 14x, 16x and 48x, which will monitor
and control the respective angular position on the basis of values Va and Va' received
by the module from the first and second position sensing means 18 and 19, and of values
Vb and Vb' derived from the master axis 14x. Alternatively, use could be made of multiple
modules controlling a plurality of axes (i.e. depending on the design of the modules)
as indicated in fig 3, where a single module 22 controls two axes.
[0044] In addition, the monitoring and control unit 21 will comprise means 23 by which to
vary the speed of the master axis 14x and as a result obtain a simultaneous adjustment
in speed of the subordinate axes driving the remaining stations of the machine, by
virtue of their connection through the respective modules 22. To provide control over
speed variations, the monitoring and control unit 21 is connected in turn to a unit
24 such as will display and allow manual or programmable changes to the variable operating
parameters utilizing suitable software.
[0045] With a machine structured in this way, a manufacturer can bring about swift changes
in the operating cycle without necessarily stopping the machine for lengthy periods
to allow adjustments, and without any loss of control over the machine units as regards
their normal operation. In the case of a straightforward variation in the operating
speed and therefore the output of the machine, the act of simply entering a new output
value gives place to a direct variation in the speed of the master motor; as a result,
all of the modules 22 will take up the new value from the master and pilot the control
unit of the connected motor (see arrows C in fig 3) to adjust and adapt the speed
of the relative shaft to the new value. Again, in the slightly less simple case of
a change to a new packaging format, for example with stacks P1 and P2 comprising a
different number of bags, the relative combination is selected by way of the unit
denoted 24; this then generates an instruction by way of the interlocked modules 22
to run the relative motors (16m and 48m in this instance) at new angular velocities
such as will produce the new format. Accordingly, with the various motors and the
corresponding axes controlled electrically, changes of speed and format can be effected
swiftly, with machine down times having very little influence on output.
[0046] The solution of first sensing means 18 keyed directly to the motor shafts is instrumental
in enabling the monitoring and control unit to recognize the angular position of the
relative machine axis at any given moment, whilst with second absolute position sensing
means 19 applied preferably to the low speed axes or located along the trajectory
of the components driven by them, the monitoring and control unit is able to establish
the position in space of a given component without reference to the number of revolutions
that must be completed by the shaft of the relative motor per operating cycle, i.e.
information dependent upon the cycle.
[0047] Another example of the flexibility afforded by the machine disclosed is reflected
in the ease with which the lines of the heat seal can be varied in relation to the
subsequent transverse cut, so as to obtain a correct alignment between the heat seal
and the cut; the operation is simple, and effected by way of the relative motor 11m.
This same flexibility is similarly evident in the process whereby the measures 4 of
the substance are dispensed onto the strip 2, inasmuch as the position of the measures
in relation to the stroke made subsequently by the transverse cutter 15 can be altered
by piloting a corresponding adjustment of the motor 8m which drives the dispensing
means 9.
[0048] With machine units interlocked to an automatic control system as described and illustrated,
positioning and timing adjustments can be made with a simplicity not afforded by prior
art machines having all-mechanical transmission linkages. Furthermore, in the event
of an interruption occasioned by a stall in the cycle or a change to a different style
of bag 1, this is handled directly by the monitoring and control unit 21 which, when
the machine restarts, will readjust the axes as required according to the relative
position occupied by each one at the moment when the stoppage occurred, and according
to the absolute position in the context of the operating cycle.
[0049] In addition, the opening and closing movement of the heat seal rollers 11a and 11b
could be automated so as to prevent any damage to the strips 2 and 3 occupying the
station 11 at the moment when a stoppage occurs.
[0050] As the rollers 11a and 11b open, the monitoring and control unit 21 will detect the
movement and cause the clamp element 31 to descend, restraining the strips of bags
1 currently advancing through the longitudinal cut; these would otherwise be pulled
back toward the heat seal rollers 11a and 11b and the already formed bags 1 consequently
lost.
[0051] A further advantage afforded by the machine disclosed is that the components of one
or more stations could be embodied as interchangeable modular assemblies and selected
on the basis of the aforementioned variable operating parameters. When changing to
a different size of film F2 and F3 utilized for a given pattern of bag 1, for example,
the heat seal rollers 11a and 11b might easily be released from the arms 42 and replaced
with others; the arms thus provide means by which the assembly is associated removably
with the respective electric motor 11m, this being a non-interchangeable part.
1. A machine for the automated manufacture of bags (1) containing infusionable substances,
in particular a bag of the type fashioned from two joined strips (2, 3) of filter
paper enveloping at least one measure (4) of the substance,
characterized
- in that it comprises a plurality of stations ordered along a pass line (A):
a first station (5) at which a first film (F2) of filter paper serving to establish
a first strip (2) is decoiled from a roll (6) and directed toward a second station;
a second station (8) at which a measure (4) of the infusionable substance is dispensed
onto the advancing first strip (2) by metering means (9) positioned along the pass
line (A), and at which the selfsame first strip (2) is joined and covered at a point
beyond the metering means (9) by a second film (F3) constituting the second strip
(3);
a third station (11) at which the united strips (2, 3) are heat sealed longitudinally
and transversely by a pair of contrarotating rollers (11a, 11b), thereby generating
a continuous strip of bags (1) ordered in linear succession;
a fourth station (14) at which the continuous strip is divided by a first transverse
cutter (15) into a plurality of discrete bags (1);
a fifth station (16) at which bags (1) advancing from the fourth station (14) are
taken up by stacking means (17) and allowed to accumulate in predetermined number
as required for subsequent packaging;
- in that at least the second, third, fourth and fifth stations (8, 11, 14, 16) are
set in motion by drive means (8m, 11m, 14m, 16m) operating independently of and synchronously
with one another, each identifiable as a relative machine axis (8x, 11x, 14x, 16x)
of which the angular position is electrically controlled;
- in that at least one of the electrically controlled axes (8x, 11x, 14x, 16x) functions
as a master axis to which all the remainder are subordinate; and,
- in that all the electrically controlled axes (8x, 11x, 14x, 16x) are interlocked
to a monitoring and control unit (21) such as will verify their angular position one
in relation to another on the basis of variable operating parameters, namely the number
of bags (1) manufactured per unit of time, the number of bags per single package and
the size and/or pattern of the individual bag.
2. A machine as in claim 1, wherein the bags (1) of the continuous strip are arranged
in pairs, two abreast and ordered in linear succession: comprising a sixth station
(12) located between the third and fourth stations (11, 14) and comprising a second
cutter (13) by which the continuous strip is cut longitudinally into two parts in
such a way as to create two parallel lines of bags advancing one alongside the other.
3. A machine as in claim 1, wherein the master axis (14x) to which the remaining axes
are subordinated coincides with the drive means (14m) of the first transverse cutter
(15) operating at the fourth station (14).
4. A machine as in claim 1, wherein each one of the electrically controlled machine axes
(8x, 11x, 14x, 16x) is equipped with first means (18) by which to monitor the angular
position of the axis in relation to the corresponding station (8, 11, 14, 16), and
second means (19) by which to monitor the absolute position in space of the machine
units (9, 11a, 11b, 15, 17) set in motion by the respective axes (8x, 11x, 14x, 16x),
the absolute position being a function of variable operating parameters programmable
by way of the monitoring and control unit (21).
5. A machine as in claim 4, wherein the monitoring and control unit (21) comprises one
circuit module (22) governing each of the electrically controlled axes (8x, 11x, 16x)
subordinate to the master axis (14x), such as will monitor and control the angular
position of the corresponding axis on the basis of values (Va, Va') received by the
module from the first and second position sensing means (18, 19), and of values (Vb,
Vb') generated by the master axis (14x).
6. A machine as in claim 4, wherein the monitoring and control unit (21) comprises one
circuit module (22) governing at least two of the electrically controlled axes (8x,
11x, 16x) subordinate to the master axis (14x), such as will monitor and control the
angular position of the corresponding axes on the basis of values (Va, Va') received
by the module from the first and second position sensing means (18, 19), and of values
(Vb, Vb') generated by the master axis (14x).
7. A machine as in claim 1, wherein the monitoring and control unit (21) comprises means
(23) by which to vary the operating speed at least of the master axis (14x), and is
connected also to a unit (24) such as will both display and allow manual or programmable
changes to the variable operating parameters.
8. A machine as in claim 1, wherein the first station (5) comprises a roll (6) from which
a single film (F) is decoiled and divided successively into two parts (F2, F3) by
longitudinal cutting means (7) to create the two strips (2, 3), of which the part
(F3) providing the second strip (3) is caused to by-pass the second station (8) through
the agency of transfer means (10) and joined thereafter to the first strip (2) at
a given point on the pass line (A) beyond the metering means (9).
9. A machine as in claim 1, wherein any one or any number of the stations (5, 8, 11,
14, 16) comprises machine units (6, 9, 11a, 11b, 15, 17) consisting in modular assemblies
that are interchangeable according to the variable operating parameters and associated
removably with the relative electric drive means (8m, 11m, 14m, 16m), which are non-interchangeable.
10. A machine as in claim 1, wherein the rollers (11a, 11b) of the third station (11)
are contrarotatable about respective horizontal axes (11ay, 11by) and disposed one
above the other, each associated at the rear of the machine with respective ends of
a pair of rods (25, 26) combining to create a toggle mechanism (27) connected pivotably
to one end of a horizontally disposed pneumatic actuator (28) by which the two rollers
(11a, 11b) can be drawn together and spread apart, in response to a command from the
monitoring and control unit (21), respectively at the start of a cycle and when the
cycle is interrupted.
11. A machine as in claim 2, wherein the continuous strip of bags (1) is divided longitudinally
by a second cutter (13) located beneath a pass line (A) followed by the strip, directly
under at least one reaction wheel (29) mounted rotatably to a block (30) secured to
the machine above the pass line (A), and the sixth station (12) further comprises
a clamp element (31) occupying a position following the reaction wheel (29) and preceding
the cutter (13) relative to the pass line, anchored slidably to the block (30) and
capable of movement vertically between an inactive raised position, distanced from
the strip in such a manner as to allow its advance, and an active lowered position
of contact assumed in response to a command from a monitoring and control unit (21)
in the event of the operating cycle being interrupted, whereby the strip is prevented
both from advancing any further and from returning toward the third station (11).
12. A machine as in claim 1, wherein stacking means (17) at the fifth station (16) consist
in at least one vertical duct (32) with open top and bottom ends designed to accommodate
the single bags (1) one on top of another and resting on a platform (33) located within
and capable of movement along the duct (32), into which the bags (1) are directed
forcibly by an arm (34) disposed transversely and adjacent to the open top end, anchored
by way of a fulcrum pivot (35) to a fixed structure (36) of the machine and capable
thus of alternating movement synchronously with the movements of the remaining stations
and in a vertical direction (V), in such a way that its free end (34a) will enter
into contact with the bags (1) advancing from the fourth station (14) and favour their
entry into the duct (32).