[0001] The present invention relates to an adhesive paper sealing machine for parallelepiped
boxes with turn-down flaps.
[0002] It is known that ecological problems have caused a return to favour of adhesive paper
sealing tapes (paper tapes provided with a small layer of adhesive applied to one
of the faces), that for years had been abandoned in favour of plastic adhesive tapes.
[0003] In the European patent application No. 0558122 a sealing machine was described using
an adhesive paper taping device that comprises a plurality of individual separately
dismantable units, among which a unit for supporting a roll of adhesive paper tape,
units for controlling, centering and feeding the tape itself, a contrasting unit co-operating
with the feeder unit, a unit for shearing and a unit for moistening the tape, and
lastly a unit for applying the tape to the top of the box to be sealed. A similar
taping device can also be provided for sealing the bottom of the box.
[0004] During the operation of such a machine, a box to be sealed is made to advance by
a pair of lateral belts along a set of rollers, and it presses in sequence a first
and a second microswitch.
[0005] The operation of the first microswitch determines the operation of the tape feeder
unit of each taping device, that causes the tape itself to advance, unwinding it from
the roll, by an amount of a predetermined length; during the tape advance, its surface
provided with glue is made to become adhesive through the action of the moistening
unit, so that, when the box arrives, it can glue itself on the front surface of the
same box, by exploiting the pressure of a roller forming part of the tape application
unit. The further advance of the box determines the operation of the second microswitch,
that releases the movement of the tape inside the machine, so that the advance of
the box causes the free unwinding of the tape from the roll, to allow the tape to
be glued on the upper surface of the box and possibly also the lower one. At the end
the tape is sheared off, and the machine is ready to start a new cycle.
[0006] The problem exhibited by the described machine is linked with the fact that, especially
with tapes whose adhesive is of poor quality, the resistance offered to the action
of unwinding the tape could, during the advancement of the box, cause the section
of the tape that is not yet perfectly glued on the front surface to come unstuck,
determining the failure of the entire sealing operation.
[0007] In view of the described state of the art, the object of the present invention is
to provide an adhesive paper sealing machine that is not affected by the abovementioned
problem.
[0008] According to the present invention such object is attained thanks to an adhesive
paper sealing machine for parallelepiped boxes with turn-down flaps, comprising a
supporting base for the boxes to be sealed, means for the advancement of the boxes
associated with said supporting base, a head that can be displaced vertically at a
variable distance with respect to said supporting base, at least one taping device
supported by said head and comprising a unit for supporting a roll of tape of adhesive
paper, a unit for feeding the tape, a contrasting unit co-operating with the unit
feeding the tape, a unit for shearing the tape, a unit for moistening the tape and
a unit for applying the moistened tape on the box to be sealed, said machine also
comprising sensor means, excited by the boxes during the advancement, for the activation
and disactivation of said feeder unit and said contrasting unit and for the activation
and disactivation of said shearing unit, characterized in that said roll of tape is
mounted in the supporting unit in a freely rotatable manner so that, following the
activation and subsequent disactivation of the feeder and contrasting units for unwinding
the initial section of the tape from the roll, the roll continues its rotation due
to inertia so as to obtain, between the supporting unit and the feeder unit, a section
of loose tape that is subsequently recovered by the advancing box without opposing
any resistance, said supporting unit also comprising braking means controlled by said
sensor means to stop the inertial rotation of the roll of tape when the operation
of sealing a box has been completed.
[0009] In a sealing machine according to the invention, the presence of the loose section
of adhesive paper tape (an abundance of tape) is such that, at least initially and
until such abundance has not exhausted itself, the tape recovered by a box to be sealed
is not held back by the inertia and by the roll rotation friction, thus preventing
the initial tape section just applied to the front of the box from coming unstuck
from the box itself.
[0010] The features of the present invention will be made more evident by the following
detailed description of an embodiment thereof, illustrated as a non-limiting example
in the enclosed drawings, wherein:
Fig. 1 is a plan view of a supporting base of a sealing machine according to the invention;
Fig. 2 is a cross-sectional view of said sealing machine taken along the vertical
longitudinal plane II-II of Fig. 1, in a first operational condition;
Fig. 3 is similar to Fig. 2, with the machine in a second operational condition;
Fig. 4 is similar to Figs. 2 and 3, with the machine in a third operational condition;
Fig. 5 shows in detail a taping device of said machine, in the operational condition
of Fig. 2;
Fig. 6 is similar to Fig. 5, but it refers to the operational condition of Fig. 3;
Fig. 7 is similar to Figs. 5 and 6, but it refers to the operational condition of
Fig. 4;
Fig. 8 is a cross-sectional view of a unit for supporting a roll of tape taken along
the line VIII-VIII of Fig. 2;
Fig. 9 shows said supporting unit in a rear view with respect to Fig. 2;
Fig. 10 is a plan view of the supporting unit;
Fig. 11 is an overall diagramme of a pneumatic circuit for operating some of the units
of the taping device of Figs. 5-7.
[0011] With reference to the drawings, and in particular to Figs. 1-4, a sealing machine
according to the invention comprises a supporting base 1 that defines a set of rollers
2 for the boxes to be sealed, and a pair of lateral advancement units 4, provided
with respective belts 5, superimposed over said supporting base 1 and that can be
moved reciprocally closer to one another, by rotating a crank 6, to allow the belts
5 to engage with opposite sides 7 of a box 3 with the purpose of causing the latter
to advance along said supporting base 1 in the direction of the arrow A. Along one
of the advancement units 4 there are in succession a first microswitch M1 and a second
microswitch M2, both provided with an operating lever 201 extending above the set
of rollers 2 in a direction orthogonal to the direction in which the boxes advance.
[0012] The machine also comprises a head 8 (Figs. 2-4) fastened to two lateral pillars 9
in a position equidistant from them; the pillars 9 can slide vertically within respective
guides 10 to arrange the head 8 at a variable distance from the supporting base 1,
so as to allow the passage of boxes to be sealed having variable height.
[0013] An upper taping device 11, designed for feeding sections of tape of adhesive paper
13 from a roll 14, is fastened to a pair of arms 12 protruding from the head 8. A
similar lower taping device is housed under the set of rollers 2 of the supporting
base 1, and is accessible through an opening 130 in the set of rollers (Fig. 1).
[0014] The taping device 11 is constituted by a plurality of individual units, separately
dismantable to allow for maintenance of the device itself, fastened to a lateral supporting
shoulder 15 to which on the opposite side there corresponds a lower containment shoulder
16; the two shoulders 15 and 16 are loosely fastened to the two protruding arms 12
(or to special supports 200 in the supporting base 1, in the case of the lower feeder
unit).
[0015] The units of the device 11 are: a unit 17 for supporting the roll 14 of the tape
13 of adhesive paper; a unit 99 for tightening the tape; a unit 18 for centering the
tape 13; a pair of co-operating plates 19 and 20 for the guidance and movement of
the tape 13; a unit 21 for feeding the tape 13 and a contrasting unit 22 associated
with the two plates 19 and 20, respectively, to determine the intermittent advancement
of the tape 13 in relation to the operating cycle of the machine; a shearing unit
23 to separate sections of the tape 13 having a pre-determined length from the continuous
tape taken from the roller 14; a moistening unit 24 for moistening the face of the
tape 13 provided with adhesive; and an application unit 25 suitable for executing
the application of the separated and moistened section of tape 13 on the box 3 to
be sealed.
[0016] As shown in Figs. 5-10, the supporting unit 17 consists of an arm 90, fastened to
the lateral shoulder 15, at the upper end of which a horizontal hub 91 is fastened.
On the hub 91 there are mounted two plates 92 and 93, of which the first is fixed
and the second is freely slidable, for the lateral containment of the roll 14 of adhesive
paper, having a diameter just larger than the diameter of the latter; the plate 93
can be removed from the hub 91 to allow the installation of the roll 14; on the inner
face of the plate 92, thanks to two screws 94 placed in diametrically opposed positions,
a flexible disc 95 is fastened. The plate 92 is also provided with a circular opening
96 located along a radial direction orthogonal to the direction joining the two screws
94; such opening allows the passage of a piston 97 of a pneumatic cylinder 98 fastened
to the plate 92. Such piston 97, when operated, pushes up against the disc 95 and
elastically deforms it (Fig. 10), to allow, as will be shown later, a braking of the
roll 14. To the plate 92 there is also fastened a pivot 107 that supports an idle
coaxial roller 108 for returning the tape 13 toward the tape tightening unit 99. The
roll 14 is mounted on the hub 91, inside the two plates 92 and 93, in a freely rotatable
manner and with the face provided with adhesive facing toward the outside of the roll,
so that said face provided with adhesive faces toward the moistening unit 24 and toward
the front wall of the box 3 advancing along the supporting base 1.
[0017] The tape tightening unit 99, visible in Figs. 5-7, consists essentially of a lever
100 hinged at 102 to a metal housing 103 in turn fastened with screws and nuts to
a box-like metal casing 37 containing the feeder unit 21; the upper end of the lever
100 has an idle roller 101 for moving the tape 13, while a spring 104 urges the same
lever 100 to a position suitable for ensuring, at rest and during the taping operation,
the tension of the tape 13 fed from the roll 14. On the housing 103 there are also
two other idle rollers 105 and 106 to return the tape 13 toward the centering unit
18.
[0018] The centering unit 18, known in itself, is identical to the centering unit of the
machine described in the European patent application No. 0558122; it comprises an
external support 26 fastened to the lateral shoulder 15 and an internal support 27
fastened to the first in an adjustable manner thanks to a bolt 203 and also fastened
to the shoulder 15 thanks to a pivot 29 having one threaded end (not visible in the
drawings), on which there is rotatably mounted an idle roller 29 provided with lateral
shoulders 30 for holding and guiding the tape 13. By loosening the bolt 203 and screwing
up the pivot 29, the internal support 27 slides inside the external support 26, it
moves the idle roller 29 and thus guiding the tape 13 of adhesive paper to the desired
position.
[0019] The pair of co-operating plates 19 and 20 consists of a lower fixed plate 20 separably
fastened to the lateral shoulder 15, and by an upper movable plate 19 rotatable with
respect to a horizontal pivot 31 separably fastened to the shoulder 15, that also
acts as the support for an idle roller 32 for returning the tape 13. The two plates
19 and 20 are at angle of about 40° to allow an easier movement of the tape 13, and
they have respective central openings 33 and 34, whose purposes will be explained
later in connection with the description of the feeder and contrasting units 21 and
22.
[0020] Two chutes 35 and 36 located at the exit from the plates 19 and 20 co-operate for
a fixed contrasting guide 65 to displace the tape 13 at an angle so as to present
it orthogonal to the moistening unit 24 and to the direction of translation of the
box 3.
[0021] The feeder unit 21 of the tape 13 comprises, as already said, the box-like metal
casing 37 fastened through nuts and screws to a corresponding casing of the underlying
shearing unit 23. Inside the box-like casing 37 there is a twin-action pneumatic cylinder
38, whose stem is connected by means of an articulated joint to a pivot 39 protruding
frontally in an eccentric position from a semicircular gearwheel 40 that directly
meshes with a toothed wheel 41 with a lower diameter to which there is eccentrically
and integrally fastened a unidirectional wheel 42 that passes through the opening
33 of the plate 19.
[0022] An abutment screw with a knob 43 fastened in an adjustable manner to the casing 37
allows the adjustment of the stroke of the cylinder 38 to be made, and thus the angular
stroke of the wheel 42, and as a consequence the length of the section of the tape
T that, due to the operation of the feeder unit 23, protrudes vertically in front
of the application unit 25 (Fig. 6).
[0023] The contrasting unit 22 comprises a box-like metal casing 44 wherein there is a single-action
pneumatic cylinder 45 with an elastic return stroke, whose stem is coupled by means
of an articulated joint with a pivot 46 that extends between two bracket levers 47
hinged at 60 on the casing 44. On the abovementioned levers 47 a rubber wheel 49 is
rotatably mounted that protrudes through the opening 34 of the plate 20 to exert a
contrasting action with the wheel 42 of the feeder unit 21 for the advancement of
the tape 13.
[0024] The linear movement of the cylinder 45 is transformed in a movement whereby the wheel
49 is moved closer to or farther away from the wheel 42, thus allowing the movement
or otherwise of the tape 13 of adhesive paper in synchronisation with the operation
of the unit 21.
[0025] The unit 23 for shearing the tape 13 comprises a box-like metal casing 50 to which
there is separably fastened the casing 37 of the feeder unit 21 of the tape and which
is in turn separably fastened to the movable plate 19. Inside the casing 50 there
is a twin-action pneumatic cylinder 51, whose stem is coupled by means of an articulated
joint to a pivot 52 that extends between two connecting rods 53 hinged at 54 on a
pair of levers 55 hinged at 56 and integrally holding a shearing blade 57 co-operating
with a fixed counterblade 58 under the thrust of a spring 59 acting on the blade holding
levers 55. Under the thrust of the cylinder 51 the connecting rods 53 push the blade
57 to shear the tape 13 of adhesive paper with the assistance of the counterblade
58 agains which the blade 57 is pressed by the spring 59.
[0026] The moistening unit 24 consists of a bowl 60 with a lateral hole 61 to which a water
feeder line 62 is connected. On the bowl 60 there is an electrical resistance 63 to
heat the moistening water so as to obtain a better activation of the glueing mass
associated with the tape 13 of adhesive paper. There is a brush 64 in the bowl's water
that by capillarity brings water into contact with the tape 13 against the contrasting
guide 65, inside which there is also an electrical resistance 66.
[0027] The unit 25 for the application of the moistened tape consists of a first lever 67
with an idle rubber-coated roller 68, a second lever 69 with an idle rubber-coated
roller 70, a centre of rotation 71 that is common to the two levers 67 and 69, and
a spring 72 that when at rest keeps the levers 67 and 69 in the close-up position
shown in Fig. 5.
[0028] A gearwheel 73 integral with the lever 67 and rotatable with the same on the centre
of rotation 71 is connected to a toothed wheel 74 centred at 75 through a chain 76,
to which the stem of a pneumatic cylinder 78 hinged at 79 on the shoulders 15 and
16 is fastened at 77. On the lever 69 there is also mounted a pneumatic valve 80.
[0029] In the at rest position the cylinder 78 is activated and its stem is retracted so
as to keep the levers 67 and 69 in the starting position, as shown in Fig. 5.
[0030] Moved by the belts 5 the box 3 acts on the roller 70 of the lever 69, causing the
rotation of the latter on the centre of rotation 71 sufficient for the disactivation
of the valve 80, that releases air from the cylinder 78.
[0031] Once the box 3 has cleared completely, the lever 67 under the action of the spring
72 is again joined together with the lever 69 determining through the chain 76 the
extension of the stem of the cylinder 78 and thus reactivating the valve 80, that
operates the retraction of the stem of the cylinder 78, that acting on the chain 76
through the connecting point 77 takes the levers 67, 69 back to the starting position.
[0032] With the tape application unit 25 there is associated a brush 81 for pressing the
tape over the box 3, that is fastened to a lever support 82 hinged at 83 on the shoulders
15 and 16 and urged in the position shown in Fig. 5 by a spring 84 reacting against
a fixed pivot 85.
[0033] With the assembly consisting of the shearing unit 23, of the feeder unit 21, of the
movable plate 19 and of the tape tightening unit 99 there co-operates a release unit
206 consisting of a pneumatic cylinder 207 hinged at 208 on the lateral shoulder 15
and with stem connected at 209 by means of an articulated joint to a bracket 210 fastened
to the metal casing 37 of the feeder unit 21. The operation of the cylinder 207, suitably
timed, allows, after a preset time has elapsed after the end of the last operating
cycle completed by the machine, to execute the opening of the path of the tape 13
between the plates 19 and 20 (the units 99, 21 and 23 rotate together with the movable
plate 19 round the centre of rotation 31), so as to prevent or in any case to eliminate
any possible jammings of the tape 13. Such opening can also be used for purposes of
periodic maintenance of the feeder unit 11.
[0034] Between the shoulders 15 and 16 there is lastly mounted a support 86 on which there
is a plurality of solenoid valves E to operate the various pneumatic cylinders described
above during the cycle of operation of the machine. A few solenoid valves of said
plurality are shown in the overall diagramme of Fig. 11. In particular, one solenod
valve E1, interlocked with the first microswitch M1, controls the flow of air in the
twin-action cylinder 38 to determine the extension or retraction of the corresponding
stem; a second solenod valve E2, interlocked with the second microswitch M2, controls
the flow of air both in the twin-action cylinder 51 and in the single-action cylinder
with an elastic return stroke 98; a third solenod valve E3, also interlocked with
the second microswitch M2, controls the flow of air in the single-action cylinder
with an elastic return stroke 45. With the cylinder 38, and with the cylinder 98 as
well, there are associated flow regulators 300 for regulating the sliding speed of
the corresponding stems; with the cylinder 51, on the othr hand, there is associated
a quick-action element 301 that allows the sharp extension of the stem necessary to
execute the shearing of the tape 13.
[0035] In operation, a box 3 to be sealed is placed on the rollers 2, and is made to advance
by the belts 5 under the head 8 of the machine. Before the box 3 operates the first
microswitch M1 (Fig. 2), the upper taping unit 11 (as well as the lower one) is in
the condition shown in Figs. 2 and 5.
[0036] The front wall of the box 3, advancing along the rollers, operates the lever 202
of the first microswitch M1 (Fig. 3). The latter triggers the solenoid valve E1 associated
with the feeder unit 21; the solenoid valve E1 operates the cylinder 38 so as to determine
the return of its stem; through the semicircular gear 40 and the toothed wheel 41,
this causes the rotation of the wheel 42 which, thanks to the contrasting action executed
by the rubber wheel 49, determines the advancement of the tape 13 toward the chutes
35 and 36 by an amount whose length is preset by the knob screw 43; the tape 13, having
gone through the chutes 35 and 36, runs between the guide 65 and the brush 64, which
moistens the adhesive on the same tape 13, and exits under the feeder unit 11 so that
a section T of moistened tape 13 hangs vertically at a given point of the path of
the advancement of the box 3 (Figs. 3 and 6).
[0037] The rotation of the two co-operating wheels 42 and 49 unwinds some tape 13 from the
roll 14; the resistance opposed by the latter to the unwinding of the tape 13 determines
an urge on the lever 100 that rotates slightly on its fulcrum 102 and moves closer
to the roll 14. When the rotation of the wheels 42 and 49 is complete, the lever 100
is returned to the at rest position by the spring 104, while the rotation of the roll
14, freely rotatable on the hub 91, continues by inertia so as to determine a looseness
205 of tape 13 that is not tight between the roll 14 and the entry to the plates 19
and 20.
[0038] With a further advancement along the rollers, the box 3 meets the section of hanging
moistened tape 13, that adheres to the front wall of the same box 3, exploiting the
pressure exerted by the roller 70 on the lever 69, urged, as already said, by the
spring 72.
[0039] At this point the box 3 operates the lever 202 of the second microswitch M2 (Fig.
4) which, activating the solenoid valve E3, determines the release of the air from
cylinder 45; this returns elastically to the at rest position, causing the rotation
of the levers 47 and as a consequence the displacement of the rubber wheel 49 away
from the wheel 42. The tape 13 can thus run freely between the plates 19 and 20 (Fig.
7).
[0040] The subsequent forward movement of the box 3 calls for tape 13; this initially determines
the elimination of the looseness 205, and only later the unwinding of tape 13 from
the roll 14. In this way the tape required initially by box 3 does not exert any resistance
to the traction on the part of the box 3, thus preventing the section T glued on the
front wall of the box 3 from coming unstuck. When, having eliminated the looseness
205, the tape 13 called for by the box 3 must be unwound from the roll 14, the resistance
to traction must no longer be overcome by the mere section of tape glued on the front
surface, but also by a section of tape glued to the upper surface of the box 3. This
naturally also holds for the section of tape glued to the lower surface of the box.
[0041] The tape 13 called for by box 3 passes in front of the brush 64, that moistens the
adhesive present on the face of the same tape.
[0042] When the box 3 is beyond the first microswitch M1 (Fig. 4) releasing the respective
operating lever 202, the solenoid valve E1 operates the extension of the stem of the
cylinder 38, to return the feeder unit 21 to the starting position (Fig. 7).
[0043] When the second microswitch M2 is also released by the box 3, this determines the
operation of the solenoid valve E3, that returns the wheel 49 to the contrasting position
with the wheel 42 (Fig. 5), and simultaneously the operation of the solenoid valve
E2 that controls both the flow of air to the cylinder 51, and consequently the operation
of the blade 57 to execute the shearing of the tape 13, and the flow of air to the
cylinder 98 so as to operate the piston 97 to determine, through the deformation of
the disc 95 (Fig. 10), a braking action on the rotation of the roll 14, which would
otherwise continue to rotate by inertia and feed further sections of tape 13 that
would create an undesired looseness.
[0044] The rear edge of tape is applied to the rear wall of the box 3 by the roller 68,
urged by the spring 72 to adhere to said rear wall.
[0045] When the box has moved past the brush 81, the cylinder 78 returns the levers 67 and
69 to the initial position of Fig.5, in the manner already described.
[0046] At this point the machine is ready to start a new operating cycle.