Information
-
Patent Grant
-
6643996
-
Patent Number
6,643,996
-
Date Filed
Friday, May 10, 200222 years ago
-
Date Issued
Tuesday, November 11, 200321 years ago
-
Inventors
-
Original Assignees
-
Examiners
- Rada; Rinaldi I.
- Desai; Hemant
Agents
- Marshall, Gerstein & Borun LLP
-
CPC
-
US Classifications
Field of Search
US
- 053 461
- 053 466
- 053 416
- 053 3762
- 053 3778
- 053 228
- 053 230
- 053 232
- 053 234
-
International Classifications
-
Abstract
A method of overwrapping packets in the form of a rectangular prism, whereby a packet, as it is fed continuously along a wrapping path, is first centered with respect to a relative conveying seat, and is then paired with a relative sheet of wrapping material, which is folded about the packet to form a tubular wrapping projecting axially from the packet in the form of two tubular appendixes, which are folded to form a closed overwrapping; each tubular appendix being at least partly folded onto the relative packet before the relative tubular wrapping is completed.
Description
The present invention relates to a method of overwrapping packets.
The present invention may be used to advantage in the tobacco industry for overwrapping packets of tobacco products, in particular packets of cigarettes, to which the following description refers purely by way of example.
BACKGROUND OF THE INVENTION
More specifically, the present invention relates to a method (for example as disclosed in EP 0135818) of overwrapping packets substantially in the form of a rectangular prism defined axially by two opposite end surfaces, and laterally by two major lateral surfaces and two minor lateral surfaces parallel to a longitudinal axis of the rectangular prism; the packets being overwrapped as they are fed, in a given feed direction, along a given wrapping path; and the method comprising, for each packet, a pairing step to pair the packet with a relative sheet of wrapping material; a first folding step to fold the sheet of wrapping material into a U about the packet so that the sheet has two projecting lateral portions, each projecting from a respective said end surface; a second folding step to further fold the sheet of wrapping material about the packet and form, about the packet, a tubular wrapping comprising two tubular appendixes projecting from respective said end surfaces of the packet and defined by said two projecting portions of the sheet; a sealing step to stabilize said tubular wrapping; and a third folding step to fold each said tubular appendix onto the respective end surface of the packet to obtain a closed overwrapping; said packet being fed continuously along said wrapping path; and each said projecting lateral portion of the sheet of wrapping material being folded at least partly onto the relative said end surface prior to said second folding step.
SUMMARY OF THE INVENTION
It is an object of the present invention to perfect the above known method to speed up the wrapping procedure, and to minimize and at the same time simplify the devices required to perform the wrapping procedure.
According to the present invention, there is provided a method of overwrapping packets substantially in the form of a rectangular prism defined axially by two opposite end surfaces, and laterally by two major lateral surfaces and two minor lateral surfaces parallel to a longitudinal axis of the rectangular prism; the packets being overwrapped as they are fed, in a given feed direction, along a given wrapping path; the method comprising, for each packet,
a pairing step to pair the packet with a relative sheet of wrapping material;
a first folding step to fold the sheet of wrapping material into a U about the packet so that the sheet of wrapping material has two projecting lateral portions, each projecting from a respective said end surface;
a second folding step to further fold the sheet of wrapping material about the packet and form, about the packet, a tubular wrapping comprising two tubular appendixes projecting from respecttive said end surfaces of the packet and defined by said two projecting lateral portions; a sealing step to stabilize said tubular wrapping;
and a third folding step to fold each said tubular appendix onto the respective end surface of the packet to obtain a closed overwrapping;
said packet being fed continuously along said wrapping path; and each said projecting lateral portion of the sheet of wrapping material being folded at least partly onto the relative said end surface prior to said second folding step;
the method being characterized by comprising, prior to said pairing step,
a centering step to center the packet with respect to said wrapping path; the centering step being performed by gripping said packet, by means of a first gripper, by two of said lateral surfaces; feeding the packet axially along a respective portion of said wrapping path by means of said first gripper; rotating said first gripper about a turn-around axis crosswise to said wrapping path and to said longitudinal axis so as to position the packet with a first of said two lateral surfaces forward; and transferring said packet to a second gripper, which grips the packet by said two end surfaces.
BRIEF DESCRIPTION OF THE DRAWINGS
A non-limiting embodiment of the present invention will be described by way of example with reference to the accompanying drawings, in which:
FIG. 1
shows a schematic side view, with parts removed for clarity, of a preferred embodiment of a machine implementing the method according to the present invention;
FIG. 2
shows a larger-scale, partial view in perspective of a first detail in
FIG. 1
;
FIG. 3
shows a larger-scale front view of a second detail in
FIG. 1
;
FIG. 4
shows a larger-scale, partial axial section of a third detail in
FIG. 1
in a succession of operating steps;
FIG. 5
shows a larger-scale, partial axial section of the
FIG. 4
detail in a further succession of operating steps;
FIG. 6
shows a temperature-time operating graph of a detail in
FIGS. 1 and 5
;
FIGS. 7
,
8
and
9
show larger-scale, partial axial sections of the
FIG. 4
detail in a further succession of operating steps;
FIG. 10
shows a larger-scale view of a fourth detail in
FIG. 1
;
FIGS. 11 and 12
show larger-scale plan views of a detail in
FIGS. 1 and 10
;
FIG. 13
shows, in perspective, a sequence for folding a sheet of wrapping material.
DETAILED DESCRIPTION OF THE INVENTION
Number
1
in
FIG. 1
indicates as a whole a machine for cellophaning packets
2
of cigarettes in the form of a substantially rectangular prism and comprising a longitudinal axis
3
; two major lateral surfaces
4
parallel to each other and to longitudinal axis
3
; two minor lateral surfaces
5
parallel to each other and to longitudinal axis
3
, and perpendicular to major lateral surfaces
4
; and two parallel end surfaces
6
perpendicular to longitudinal axis
3
.
Machine
1
comprises a substantially horizontal input belt conveyor
7
for feeding an orderly succession of packets
2
on edge, i.e. with a minor lateral surface
5
resting on input conveyor
7
, in an axial direction
8
; and a centering unit
9
in turn comprising a turn-around wheel
10
substantially tangent to input conveyor
7
and for successively removing packets
2
off input conveyor
7
in direction
8
and turning each 90° about a turn-around axis
11
perpendicular to relative longitudinal axis
3
and to relative minor lateral surfaces
5
, and a folding conveyor defined by a folding wheel
12
for successively receiving the turned-around on-edge packets
2
from turn-around wheel
10
, and respective sheets
13
of wrapping material, normally polypropylene, from a feed unit
14
, and for folding sheets
13
of wrapping material into an L about respective packets
2
.
Machine
1
also comprises a further folding conveyor defined by a folding wheel
15
for receiving the on-edge packets
2
and respective L-folded sheets
13
of wrapping material, and for forming about each packet
2
a tubular wrapping
16
coaxial with longitudinal axis
3
of respective packet
2
. Each tubular wrapping
16
comprises a minor lateral wall defined by two superimposed, sealed end portions
17
and
18
of respective sheet
13
of wrapping material; and two tubular axial appendixes
19
, each of which is defined by a respective lateral portion
33
of respecttive sheet
13
of wrapping material projecting axially from relative end surface
6
of relative packet
2
, and comprises two minor walls
20
and
21
substantially coplanar with relative minor lateral surfaces
5
of relative packet
2
, and two major walls
22
and
23
substantially coplanar with relative major lateral surfaces
4
of relative packet
2
.
Machine
1
also comprises an output conveyor
24
for feeding packets
2
successively to an output of machine
1
and for closing the ends of relative tubular wrappings
16
; and a transfer unit
25
for feeding packets
2
and relative tubular wrappings
16
successively from folding wheel
15
to output conveyor
24
.
Input conveyor
7
, centering unit
9
, folding wheel
15
, transfer unit
25
and output conveyor
24
define, along machine
1
, a substantially sinusoidal wrapping path P.
Turn-around wheel
10
is fitted to a frame (not shown) over the output end of input conveyor
7
to rotate continuously clockwise, in
FIG. 1
, about a respective axis
26
crosswise to feed direction
8
. Turn-around wheel
10
comprises a powered disk
27
coaxial with and rotating about axis
26
; and a number of gripping heads
28
equally spaced about axis
26
and fitted to disk
27
to oscillate, with respect to disk
27
and under the control of a known cam device (not shown), about respective axes
29
parallel to axis
26
. Each gripping head
28
comprises a respective gripper
30
, which extends along an axis
31
located radially with respect to relative axis
29
, projects outwards of disk
27
, and comprises two jaws
32
movable, with respect to each other in a direction crosswise to relative axis
31
and by virtue of a known cam actuating device (not shown), to and from a closed position in which the two jaws
32
define a relative seat
34
for a relative packet
2
positioned with a minor lateral surface
5
facing axis
26
, and with major lateral surfaces
4
contacting jaws
32
. Each gripper
30
is connected to the rest of relative gripping head
28
to rotate in 90° steps about relative axis
31
by virtue of a known cam actuating device (not shown).
In actual use, each gripper
30
approaches input conveyor
7
in a radial position with respect to axis
26
and with jaws
32
in an open position and parallel to feed direction
8
. On nearing a transfer station
35
where packets
2
are transferred from input conveyor
7
to turn-around wheel
10
, each gripper
30
is accelerated angularly with respect to disk
27
by rotating relative gripping head
28
about relative axis
29
in the same direction as disk
27
; which rotation is inverted on gripper
30
reaching transfer station
35
, so as to maintain gripper
30
substantially stationary with respect to relative packet
2
on input conveyor
7
, and so enable packet
2
to penetrate transversely between jaws
32
. At this point, gripper
30
is closed onto major lateral surfaces
4
of relative packet
2
, and is reaccelerated to remove packet
2
off input conveyor
7
and feed it to a further transfer station
36
where packet
2
is transferred from turn-around wheel
10
to folding wheel
12
.
As relative packet
2
is fed between transfer stations
35
and
36
, each gripper
30
is turned 90° about relative axis
31
to turn relative packet
2
from an initial position in which packet
2
travels, as on input conveyor
7
, with an end surface
6
forward, to a final transfer position in which relative packet
2
travels with a major lateral surface
4
forward.
Folding wheel
12
is fitted to a frame (not shown) in a position substantially tangent to turn-around wheel
10
so as to rotate continuously anticlockwise, in
FIG. 1
, about a respective axis
37
parallel to axis
26
. Folding wheel
12
comprises a powered disk
38
coaxial with and rotating about axis
37
; and a number of gripping heads
39
equally spaced about axis
37
and fitted to disk
38
to oscillate, with respect to disk
38
and under the control of a known cam device (not shown), about respective axes
40
parallel to axis
37
. Each gripping head
39
comprises a respective gripper
41
, which extends along an axis
42
located radially with respect to relative axis
40
, projects outwards of disk
38
, and comprises two jaws
43
movable, with respect to each other in a direction parallel to relative axis
40
and by virtue of a known cam actuating device (not shown), to and from a closed position in which the two jaws
43
define a relative seat
45
for a relative packet
2
positioned with a minor lateral surface
5
—opposite the one formerly facing axis
26
of turn-around wheel
10
—facing axis
37
, and with end surfaces
6
contacting jaws
43
.
From a lateral surface of each gripping head
39
, located frontwards with reference to the rotation direction of folding wheel
12
, a transverse plate
46
, parallel to relative axis
40
and located between relative seat
45
and relative axis
40
, projects frontwards and acts as a stop for a front edge of a relative sheet
13
of wrapping material fed by feed unit
14
to a supply station
47
, downstream from transfer station
36
, substantially synchronously with the passage of a gripping head
39
through supply station
47
.
More specifically, feed unit
14
, of known type, comprises a plate
48
parallel to and positioned radially with respect to axis
37
, and which is substantially C-shaped with the concavity facing the periphery of folding wheel
12
to define a passage
49
for grippers
41
and relative packets
2
; and two belts
50
, which are permeable to air and provide for feeding sheets
13
of wrapping material along a surface
51
of plate
48
, located frontwards in the traveling direction of gripping heads
39
and having suction holes for retaining sheets
13
of wrapping material in contact with belts
50
and in a position closing passage
49
.
Each gripping head
39
comprises a further gripper
52
defined by a fixed jaw in turn defined by a body of gripping head
39
, and by a movable jaw
53
which pivots about relative axis
40
to oscillate, with respect to the body of relative head
39
, between an open position and a closed position in which an end pad
54
of jaw
53
is positioned radially outwards of relative plate
46
and contacting, at relative seat
45
, the major lateral surface
4
of relative packet
2
located frontwards in the rotation direction of folding wheel
12
.
Folding wheel
12
is also provided with a fixed folding and guide plate
55
extending, coaxially with axis
37
, between supply station
47
and a transfer station
56
where packets
2
and relative sheets
13
of wrapping material are transferred to folding wheel
15
. At the end facing supply station
47
, plate
55
has a rounded edge
57
for folding each sheet
13
of wrapping material onto the outer minor lateral surface
5
—opposite the one facing axis
37
—of relative packet
2
; and, on the side facing the periphery of folding wheel
12
, plate
55
has a suction surface
58
for braking and smoothing sheets
13
of wrapping material onto said relative outer minor lateral surfaces
5
.
In actual use, each gripping head
39
approaches transfer station
36
with grippers
41
and
52
in the open position to enable jaws
43
to receive a relative packet
2
fed to transfer station
36
by a corresponding gripper
30
on turn-around wheel
10
; and, at transfer station
36
, jaws
43
are moved into the closed position contacting respective end surfaces
6
of relative packet
2
to clamp packet
2
in an axial position in which the longitudinal axis
3
of packet
2
is parallel to axis
37
, one of minor lateral surfaces
5
of packet
2
faces axis
37
, and the two major lateral surfaces
4
of packet
2
are positioned substantially radially with respect to disk
38
. Turn-around wheel
10
and folding wheel
12
are located such a distance apart that each jaw
43
in the closed position only cooperates with part of the length of relative end surface
6
of relative packet
2
, and leaves exposed an outer portion of relative end surface
6
of a length, measured along axis
42
, at least equal to the length of a tubular appendix
19
.
In connection with the way in which each packet
2
is fed by input conveyor
7
to folding wheel
12
as described previously, it should be pointed out that, when a packet
2
is gripped by a relative gripper
30
on turn-around wheel
10
, the position of the packet with respect to relative gripper
30
is undoubtedly correct in a radial direction with respect to disk
27
, but may be slightly incorrect in a circumferential direction with respect to disk
27
, so that, when packet
2
reaches transfer station
36
, its position with respect to relative seat
45
is undoubtedly correct in a radial direction with respect to disk
38
, but may be slightly off-center with respect to relative seat
45
in a direction parallel to axis
37
. Any axial position error, however, is corrected upon relative gripper
30
opening and relative gripper
41
simultaneously closing, so that each packet
2
, once transferred onto folding wheel
12
, is perfectly centered radially, axially and circumferentially with respect to disk
38
.
On receiving relative packet
2
, each gripping head
39
moves towards supply station
47
supplying sheets
13
, and gripper
41
engages passage
49
of plate
48
. At the same time, a relative sheet
13
of wrapping material is supplied by feed unit
14
so that, as relative gripper
41
engages passage
49
, the front edge of sheet
13
of wrapping material is arrested on plate
46
and remains in this position as sheet
13
contacts the front major lateral surface
4
of relative packet
2
and relative gripper
52
simultaneously closes to clamp sheet
13
onto front major lateral surface
4
of relative packet
2
and so enable relative gripping head
39
to detach sheet
13
from front suction surface
51
of plate
48
and insert it, together with relative packet
2
, beneath plate
55
.
As the part of sheet
13
projecting outwards of relative packet
2
contacts folding edge
57
of plate
55
, sheet
13
is folded into an L about relative packet
2
so that a first portion projects inwards, with respect to front major lateral surface
4
of relative packet
2
, to form relative end portion
18
; a second portion centrally contacts front major lateral surface
4
of relative packet
2
; a third portion centrally contacts the outer minor lateral surface
5
of relative packet
2
; and a final portion, indicated
13
a
, projects rearwards with respect to outer minor lateral surface
5
, is retained by suction on suction surface
58
of plate
55
, and is therefore braked by plate
55
to smooth sheet
13
perfectly onto front major lateral surface
4
and outer minor lateral surface
5
of relative packet
2
.
Each sheet
13
is maintained in this position until relative gripping head
39
reaches transfer station
56
.
Folding wheel
15
is fitted to a fixed frame (not shown) in a position substantially tangent to folding wheel
12
to rotate continuously clockwise, in
FIG. 1
, about an axis
59
parallel to axis
37
, and comprises a powered disk
60
coaxial with axis
59
and having a succession of radial pockets
61
open both-radially and axially outwards and each for receiving a relative packet
2
with relative sheet
13
of wrapping material.
Each pocket
61
is defined by a fixed wall
62
parallel to and positioned radially with respect to axis
59
and at the front in the rotation direction of folding wheel
15
, and by a movable wall
63
, which pivots on disk
60
to rotate, about a respecttive axis
64
, to and from a closed position in which movable wall
63
is separated from relative fixed wall
62
by a distance approximately equal to but no less than the distance between major lateral surfaces
4
of packet
2
. Two fixed folding devices
65
are provided across pocket
61
, and are each defined by a plate between fixed wall
62
and movable wall
63
, in a plane perpendicular to axis
59
, and separated from the corresponding plate of the other fixed folding device
65
by a distance approximately equal to but no less than the distance between end surfaces
6
of packet
2
. Each fixed folding device
65
is of a width, measured radially with respect to axis
59
, smaller than the length of tubular appendixes
19
, and is defined by a rounded outer edge, and by a flat inner edge, which, together with the flat inner edge of the other fixed folding device
65
, defines a surface
66
parallel to axis
59
, perpendicular to relative fixed wall
62
, and defining an end surface of relative pocket
61
.
A pusher
67
is mounted to slide along each pocket
61
, and is movable radially along relative pocket
61
to and from a withdrawn position in which an end surface of pusher
67
is positioned facing outwards and coplanar with surface
66
.
Each pocket
61
is provided with a fold-and-seal device
68
located on the fixed wall
62
side of relative seat
61
, and which comprises a sleeve
69
hinged in a substantially radial position to disk
60
to oscillate about a respective fixed axis
70
parallel to axis
59
, and a rod
71
mounted to slide along sleeve
69
and having a portion projecting outwards from sleeve
69
. Rod
71
is controlled by a respective powered connecting rod
72
, which is hinged to disk
60
to oscillate about an axis
73
parallel to axis
59
, and is fitted on the free end with a pin
74
parallel to axis
59
and engaged in transversely sliding manner inside a slot
75
extending longitudinally along said projecting portion of rod
71
. In normal working conditions, a spring
76
, stretched between an inner end of rod
71
and a point on disk
60
, maintains rod
71
in a normally withdrawn position with respect to sleeve
69
and with pin
74
resting transversely on the outer end of slot
75
.
The portion of rod
71
projecting outwards from the outer end of relative sleeve
69
is fitted on the free end—located along the periphery of disk
60
, at a distance from relative surface
66
substantially equal to the distance between minor lateral surfaces
5
of packet
2
when rod
71
is in the normal withdrawn position—with a crosspiece
77
facing relative pocket
61
and fitted, at the end of its surface facing axis
59
, with a sealing bar
78
extending parallel to axis
59
along the whole of relative pocket
61
, and substantially of the same length as tubular wrapping
16
. Rod
71
, together with relative sleeve
69
, is oscillated by relative connecting rod
72
about axis
70
to slide crosspiece
77
, along a peripheral surface of disk
60
, between a position opening and a position substantially closing an inlet
79
of relative pocket
61
, and in which sealing bar
78
is positioned as described below.
The oscillating movements of movable walls
63
and connecting rods
72
, and the radial movements of pushers
67
are controlled by relative known cam actuating devices (not shown) fitted to disk
60
.
In actual use, as an empty pocket
61
approaches transfer station
56
to receive a respecttive packet
2
from a respective gripping head
39
on folding wheel
12
, relative crosspiece
77
is set to the position opening relative inlet
79
, relative movable wall
63
is set to the open position, and relative pusher
67
is set to the withdrawn position with its outer end on a level with relative surface
66
. As it is fed through transfer station
56
, said packet
2
, still retained by relative gripper
41
, is eased inside pocket
61
, together with relative sheet
13
of wrapping material, by oscillating relative gripping head
39
in known manner about relative axis
40
. As packet
2
is inserted inside relative pocket
61
, relative sheet
13
of wrapping material is folded into a U about packet
2
so as to contact the two major lateral surfaces
4
of packet
2
and the minor lateral surface
5
formerly facing plate
55
and now facing axis
59
of folding wheel
15
.
At the same time, pusher
67
is moved outwards to contact and ease relative packet
2
down inside relative pocket
61
. In this connection, it should be stressed that the main purpose of pusher
67
is to hold relative sheet
13
of wrapping material in place on relative packet
2
and prevent it from sliding out of position with respect to packet
2
.
As packet
2
moves down inside relative pocket
61
, the two minor lateral walls
20
of sheet
13
of wrapping material projecting from end surfaces
6
of packet
2
encounter relative fixed folding devices
65
, by which they are folded onto and retained on respective end surfaces
6
.
Once packet
2
is-inserted completely inside relative pocket
61
, with inner minor lateral surface
5
coplanar with surface
66
, and with outer minor lateral surface
5
tangent to a peripheral surface of disk
60
, grippers
41
and
52
are opened to release packet
2
onto folding wheel
15
, and relative movable wall
63
is moved into the closed position to secure packet
2
and relative sheet
13
of wrapping material inside relative pocket
61
, with sheet
13
of wrapping material folded into a U about packet
2
so that relative end portions
17
and
18
project radially outwards of inlet
79
of relative pocket
61
.
Packet
2
is then fed by folding wheel
15
to a folding station
80
, where an outer folding device
81
, guided cyclically in known manner by a known actuating device (not shown) along an endless path P
1
having a branch tangent to the outer periphery of disk
60
, folds end portion
17
—located behind relative end portion
18
in the traveling direction of relative packet
2
—forward onto outer minor lateral surface
5
of relative packet
2
. At the same time, before folding device
81
moves back after releasing the folded end portion
17
, fold-and-seal device
68
is moved into the closed position to fold relative end portion
18
onto outer minor lateral surface
5
of relative packet
2
, with an end portion of end portion
18
overlapping relative end portion
17
and directly beneath sealing bar
78
, which seals end portions
17
and
18
to form relative tubular wrapping
16
before packet
2
reaches a transfer station
82
where packet
2
, together with relative tubular wrapping
16
, is extracted from relative pocket
61
by transfer unit
25
and transferred to output conveyor
24
.
It should be pointed out that sealing bar
78
is designed for minimum thermal inertia, is maintained, for most of the time taken to make a complete turn about axis
59
, at a relatively low working temperature, preferably about 80° C., and, as soon as relative fold-and-seal device
68
moves into the closed position, is brought to a higher sealing temperature, preferably about 120° C., for a constant time period T independent of the rotation speed of folding wheel
15
, so as to prevent any variation in the rotation speed of folding wheel
15
from resulting in nonsealing of tubular wrappings
16
or in singeing of sheets
13
of wrapping material.
Just before reaching transfer station
82
, fold-and-seal device
68
is moved into the open position to permit withdrawal of relative packet
2
and relative tubular wrapping
16
from relative pocket
61
. To prevent relative crosspiece
77
, as it moves into the open position, from detaching relative end portion
18
just folded and sealed onto relative end portion
17
, crosspiece
77
, before moving into the open position, is attracted outwards, in opposition to relative spring
76
and so that relative pin
74
cooperates transversely with the inner end of relative slot
75
, by a permanent magnet
83
located outwards of the outer periphery of disk
60
, immediately upstream from transfer station
82
, so that crosspiece
77
is detached from relative tubular wrapping
16
before moving into the open position, and is kept detached throughout the opening movement.
Output conveyor
24
comprises an endless belt
84
extending about a pulley
85
, which is substantially tangent to disk
60
of folding wheel
15
, is fitted to a frame (not shown) to rotate continuously anticlockwise, in
FIG. 1
, about an axis
86
parallel to axis
59
, and defines, on belt
84
, a substantially horizontal conveying branch
87
and a substantially horizontal return branch
88
. Teeth
89
project outwards from belt
84
to define a succession of conveying pockets
90
, each for receiving, on conveying branch
87
, a packet
2
complete with relative tubular wrapping
16
and positioned with a major lateral surface
4
facing conveying branch
87
, and with longitudinal axis
3
crosswise to the traveling direction
91
of conveying branch
87
.
At one axial end, pulley
85
has an annular flange
92
forming part of a transfer wheel
93
, which, together with pulley
85
, defines transfer unit
25
. In addition to flange
92
, transfer wheel
93
also comprises a number of grippers
94
equally spaced about axis
86
and which oscillate on flange
92
about respective hinge axes
95
parallel to axis
86
.
Each gripper
94
comprises two jaws
96
, each of which is defined by a relative metal strip bent substantially into an S and preferably narrower than half the distance between the two major lateral surfaces
4
of a packet
2
. Each jaw
96
comprises an inner portion
97
pivoting on flange
92
; and an outer portion
98
of a length substantially equal to the distance between the minor lateral surfaces
5
of a packet
2
minus twice the length of one of the two tubular appendixes
19
of tubular wrappings
16
. Inner and outer portions
97
and
98
of each jaw
96
are substantially parallel to each other, are crosswise to relative axis
95
, and are connected to each other by an intermediate portion
99
substantially parallel to relative axis
95
, extending from an outer end of relative inner portion
97
towards the other jaw
96
, and longer than one of tubular appendixes
19
of tubular wrappings
16
. The two jaws
96
of each gripper
94
are movable, along relative axis
95
, between a closed position in which relative outer portions
98
are separated by a distance substantially equal to the distance between end surfaces
6
of a packet
2
, and an open position in which relative outer portions
98
are separated by a distance greater than the length of a tubular wrapping
16
.
In actual use, as soon as relative crosspiece
77
moves into the open position opening relative inlet
79
, each pocket
61
inserts relative packet
2
and relative tubular wrapping
16
between the outer portions
98
of open jaws
96
of a relative gripper
94
fed by transfer wheel
93
to transfer station
82
in time with said pocket
61
. Jaws
96
of gripper
94
being open, the whole of tubular wrapping
16
of relative packet
2
can be inserted between jaws
96
without tubular appendixes
19
engaging relative outer portions
98
. At this point, packet
2
and relative gripper
94
are fed together to transfer station
82
, while gripper
94
, oscillating in known manner about respective axis
95
by means of a known cam device (not shown), is kept aligned with relative pocket
61
, with the outer portion
98
of each jaw
96
facing a respective end surface
6
of relative packet
2
adjacent to the major lateral wall
23
of relative tubular appendix
19
. At transfer station
82
, pusher
67
begins moving outwards to insert relative packet
2
completely inside relative pocket
90
. When packet
2
is inserted fully inside relative pocket
90
, outer portion
98
of each jaw
96
is positioned with an outer end portion facing the portion of minor lateral wall
20
of relative tubular appendix
19
projecting from relative fixed folding device
65
, and with its inner end separated from the minor lateral wall
21
of relative tubular appendix
19
by a distance greater than the length of relative minor lateral wall
21
.
At this point, gripper
94
is closed to secure relative packet
2
to transfer wheel
93
, and to keep the minor lateral walls
20
of tubular appendixes
19
of packet
2
in the folded position. At the same time, movable wall
63
of relative pocket
61
is moved into the open position to release and enable removal of relative packet
2
by relative gripper
94
.
On gripping relative packet
2
, gripper
94
continues oscillating about relative axis
95
and rotating about axis
86
to feed relative packet
2
, complete with relative tubular wrapping
16
, to the input of conveying branch
87
in such a position that a major lateral surface
4
is substantially coplanar with conveying branch
87
, and to insert packet
2
inside a relative pocket
90
at a release station
100
where gripper
94
is opened to release the packet onto output conveyor
24
.
In the course of the above operation, and before relative packet
2
is inserted fully inside relative pocket
90
, gripper
94
inserts packet
2
between two folding rods
101
extending along opposite sides of conveying branch
87
, parallel to traveling direction
91
, and separated by a distance approximately equal to but no less than the distance between end surfaces
6
of packet
2
. More specifically, each folding rod
101
comprises a relatively narrow initial portion
102
located entirely upstream from release station
100
and for interfering with a portion of relative end surface
6
left exposed by outer portion
98
of relative jaw
96
; and a following wider portion
103
, which commences immediately upstream from release station
100
and is wide enough to interfere with the whole of relative end surface
6
.
In actual use, each initial portion
102
of each folding rod
101
interferes with part of minor lateral wall
21
of relative tubular appendix
19
to fold minor lateral wall
21
at least partly onto relative end surface
6
of relative packet
2
and subsequently secure in position the relative minor lateral wall
20
already folded by fixed folding devices
65
. Just before reaching release station
100
, portion
103
intervenes to fold relative minor lateral wall
21
completely and perfectly, and the gripper
94
is opened just before the inner end of outer portion
98
of relative jaws
96
reach a sloping input edge of portion
103
.
At this point, each tubular appendix
19
has been reduced to two straightforward wings
104
defined by part of respective major lateral walls
22
and
23
, and which are folded one on top of the other in known manner by respective cylindrical spiral folding devices
104
and
105
, and sealed to each other by a respective known sealing device (not shown) to form a closed overwrapping
107
.
Claims
- 1. A method of overwrapping packets substantially in the form of a rectangular prism defined axially by two opposite end surfaces (6), and laterally by two major lateral surfaces (4) and two minor lateral surfaces (5) parallel to a longitudinal axis (3) of the rectangular prism; the packets (2) being overwrapped as they are fed, in a given feed direction, along a given wrapping path (P); the method comprising, for each packet (2),a pairing step to pair the packet (2) with a relative sheet (13) of wrapping material; a first folding step to fold the sheet (13) of wrapping material into a U about the packet (2) so that the sheet (13) of wrapping material has two projecting lateral portions (33), each projecting from a respective said end surface (6); a second folding step to further fold the sheet (13) of wrapping material about the packet (2) and form, about the packet (2), a tubular wrapping (16) comprising two tubular appendixes (19) projecting from respective said end surfaces (6) of the packet (2) and defined by said two projecting lateral portions (33); a sealing step to stabilize said tubular wrapping (16); and a third folding step to fold each said tubular appendix (19) onto the respective end surface (6) of the packet (2) to obtain a closed overwrapping (107); said packet (2) being fed continuously along said wrapping path (P); and each said projecting lateral portion (33) of the sheet (13) of wrapping material being folded at least partly onto the relative said end surface (6) prior to said second folding step; the method being characterized by comprising, prior to said pairing step, a centering step to center the packet (2) with respect to said wrapping path (P); the centering step being performed by gripping said packet (2), by means of a first gripper (30), by two (4) of said lateral surfaces (4, 5); feeding the packet (2) axially along a respective portion of said wrapping path (P) by means of said first gripper (30); rotating said first gripper (30) about a turn-around axis (11) crosswise to said wrapping path (P) and to said longitudinal axis (3) so as to position the packet with a first of said two lateral surfaces (4) forward; and transferring said packet (2) to a second gripper (41), which grips the packet (2) by said two end surfaces (6).
- 2. A method as claimed in claim 1, wherein said packet (2) is rotated around about said turn-around axis (11), as the packet (2) is fed along the wrapping path (P).
- 3. A method as claimed in claim 2, wherein said two lateral surfaces (4) are said major lateral surfaces (4).
- 4. A method as claimed in claim 3, wherein said first folding step comprises a first substep in which said sheet (13) of wrapping material is folded into an L; and a second substep in which the L-folded said sheet (13) of wrapping material is further folded into a U.
- 5. A method as claimed in claim 4, wherein said first substep is performed by securing said sheet (13) of wrapping material with respect to said packet (2) so that a central portion of an intermediate portion of the sheet (13) of wrapping material is positioned contacting a first said lateral surface (4) facing forward in said feed direction, a first end portion of the sheet (13) of wrapping material projects from said first lateral surface (4), and a remaining portion (13a) of the sheet (13) of wrapping material projects from said first lateral surface (4), on the opposite side to said first end portion (18); and by folding said remaining portion (13a) of the sheet (13) of wrapping material squarely and rearwards with respect to said feed direction.
- 6. A method as claimed in claim 5, wherein, once folded squarely, said remaining portion (13a) is braked to smooth said sheet (13) of wrapping material onto said packet (2).
- 7. A method as claimed in claim 6, wherein said remaining portion (13a) is braked by suction.
- 8. A method as claimed in claim 7, wherein said remaining portion (13a) is folded squarely and rearwards by feeding the packet (2) along said wrapping path (P) and by interference with a fixed folding member (55) comprising a folding edge (57) for folding said remaining portion (13a) rearwards, and a following suction surface (58) extending along said wrapping path (P) and cooperating with the folded said remaining portion (13a) to smooth said sheet (13) of wrapping material onto the packet (2).
- 9. A method as claimed in claim 8, wherein said second substep is performed by transferring the packet (2) and the L-folded said sheet (13) of wrapping material from a first (45) to a second (61) seat, which move along respective portions of said wrapping path (P) and are positioned facing each other during transfer; the U-folded said sheet (13) of wrapping material being arranged inside said second seat (61) so that a first (18) and a second (17) end portion of the sheet (13) of wrapping material project from an inlet (79) of said second seat (61) and towards said first seat (45), and each said projecting lateral portion (33) of the sheet (13) of wrapping material projects from said second seat (61) crosswise to said first and said second end portion (18, 17).
- 10. A method as claimed in claim 9, wherein said projecting lateral portion (33) of the sheet of wrapping material is folded at least partly onto the relative said end surface (6) in the course of said second substep.
- 11. A method as claimed in claim 10, wherein the U-folded said sheet (13) of wrapping material is arranged contacting a first and a second said lateral surface (4, 4) and a third said lateral surface (5) between the first and second said lateral surface (4, 4); a portion of each said projecting lateral portion (33), coplanar with said third lateral surface (5), being folded onto the relative said end surface (6) in the course of said second substep.
- 12. A method as claimed in claim 11, wherein each said projecting lateral portion (33) of the sheet of wrapping material is folded at least partly onto the relative said end surface (6) by interference with a respective folding device (65) fixed to said second seat (61).
- 13. A method as claimed in claim 12, wherein, in the course of said second substep, a portion of said sheet (13) of wrapping material is secured to said packet (2).
- 14. A method as claimed in claim 13, wherein each said projecting lateral portion (33) of the sheet of wrapping material is folded partly onto the relative said end surface (6) by transferring the packet (2) and said sheet (13) of wrapping material from a first (45) to a second (61) seat, which move along respective portions of said wrapping path (P) and are positioned facing each other during transfer; said first seat (45) cooperating with said packet (2) at said end surfaces (6) and so that each said end surface (6) has a projecting portion projecting outwards of said first seat (45) by a length at least equal to a width of the relative said projecting lateral portion (33); a portion (20) of each said projecting lateral portion (33), located at a respective said projecting portion of the relative end surface (6), being folded onto the relative end surface (6) as the packet (2) and the relative sheet (13) of wrapping material are transferred from said first (45) to said second (61) seat.
- 15. A method as claimed in claim 14, wherein said portion (20) of each projecting lateral portion (33) is folded onto the relative projecting portion of the relative end surface (6) by interference with a respective folding device (65) fixed to said second seat (61).
- 16. A method as claimed in claim 15, wherein said packet (2) and the sheet (13) of wrapping material are inserted inside said second seat (61) while maintaining a portion of said sheet (13) of wrapping material secured in place on said packet (2).
- 17. A method as claimed in claim 16, wherein said portion of the sheet (13) of wrapping material is secured in place on the packet (2) by means of a pusher (67) movable along said second seat (61) to and from said first seat (45).
- 18. A method as claimed in claim 17, herein said second folding step is performed by inserting the packet (2) and the U-folded said sheet (13) of wrapping material inside a conveying pocket (61), so that a first (18) and a second (17) end portion of the sheet (13) of wrapping material project from an inlet (79) of said conveying pocket (61) and crosswise to said wrapping path (P), with said first end portion (18) in front of said second end portion (17) in said feed direction; feeding said conveying pocket (61) through a folding station (80), located along said wrapping path (P), to fold said second end portion (17) squarely in said feed direction; and moving a folding member (68), movable with said conveying pocket (61) along said wrapping path (P), across said inlet (79) in the opposite direction to said feed direction and from an open position opening to a closed position closing said inlet (79) to fold said first end portion (18) squarely onto said first end portion (17) so that said first and said second end portion (18, 17) have an overlapping portion.
- 19. A method as claimed in claim 18, wherein said folding member (68) is a fold-and-seal device comprising a sealing element (78) which, when the folding member (68) is in said closed position, is located at said overlapping portion; said folding member (68) being maintained in said closed position along a given portion of said wrapping path (P); and said sealing step being performed as said folding member (68) is fed along said given portion of the wrapping path (P).
- 20. A method as claimed in claim 19, wherein said sealing element (78) is temperature-controlled to normally remain at a relatively low, substantially constant temperature, and to assume a relatively high sealing temperature for a constant time interval as it is fed along said given portion of the wrapping path (P).
- 21. A method as claimed in claim 20, wherein said sealing step is performed by means of a sealing element (78) movable with said packet (2) and said tubular wrapping (16) along a portion of said wrapping path (P); said sealing element (78) being temperature-controlled to normally remain at a relatively low, substantially constant temperature, and to assume a relatively high sealing temperature for a constant time interval as it is fed along said given portion of the wrapping path (P).
- 22. A method as claimed in claim 21, wherein said relatively low temperature is about 80° C.
- 23. A method as claimed in claim 22, wherein said sealing temperature is about 120° C.
- 24. A method as claimed in claim 23, wherein, at least in the course of said folding steps, said packet (2) is fed along said wrapping path (P) with one (4) of said lateral surfaces (4, 5) forward in said feed direction.
- 25. A method as claimed in claim 24, wherein, at least in the course of said pairing step and said first and second folding step, said packet (2) is fed along said wrapping path (P) with one of said major lateral surfaces (4) forward in said feed direction.
- 26. A method as claimed in claim 25, wherein, at least in the course of said third folding step, said packet (2) is fed along said wrapping path (P) with one of said minor lateral surfaces (5) forward in said feed direction.
- 27. A method as claimed in claim 26, wherein, in the course of said pairing and folding steps, said packet (2) is fed along said wrapping path (P) with one of said lateral surfaces (4, 5) forward in said feed direction; said pairing step being performed at a pairing station (47) located at a given point along said wrapping path (P); and, at least along a portion of said wrapping path (P) upstream from said pairing station (47), the packet (2) being fed with a said end surface (6) forward in said feed direction.
- 28. A method as claimed in claim 27, wherein said packet (2) is fed along at least part of said wrapping path (P) by means of a succession of wheels (10, 12, 15, 93) which transfer the packet (2) at a succession of transfer stations (36, 56, 82); each wheel (10, 12, 15, 93) having at least one respective gripping member (30, 41, 61, 94) for said packet (2), and being located adjacent to at least one other said wheel (10, 12, 15, 93); and, at each pair of adjacent said wheels (10, 12; 12, 15; 15, 93), the gripping member of one of the two adjacent wheels (10, 12; 12, 15; 15, 93) cooperating with two parallel, opposite said lateral surfaces (4, 5) of said packet (2), and the gripping member of the other wheel cooperating with said end surfaces (6) of said packet (2).
Priority Claims (1)
Number |
Date |
Country |
Kind |
BO2001A00290 |
May 2001 |
IT |
|
US Referenced Citations (8)
Foreign Referenced Citations (2)
Number |
Date |
Country |
0 135 818 |
Apr 1985 |
EP |
0 900 731 |
Mar 1999 |
EP |