Method of continuously feeding wrapping elements in sheet form to a user machine

A method of continuously feeding wrapping elements in sheet form to a continuously-rotating input roller of a wrapping machine, whereby each element is withdrawn from the output of a feedbox by a curved gripping member rolled onto the element at the output of the feedbox, is fed along a given path by moving the gripping member continuously along the path, and is released onto the conveying surface of the input roller by rolling the gripping member on the surface of the roller.

BACKGROUND OF THE INVENTION 
The present invention relates to a method of continuously feeding wrapping 
elements in sheet form to a user machine. 
More specifically, the present invention relates to a method of feeding 
wrapping elements in sheet form to a continuous user machine presenting a 
continuously-rotating input conveyor roller for the wrapping elements. 
In general, wrapping elements are supplied to a continuous user machine by 
withdrawing the elements successively and intermittently from a feedbox, 
and feeding them in steps to an intermediate feed device located between 
the feedbox and the user machine and for accelerating the elements to feed 
them continuously to the input roller of the user machine. 
The above method presents several drawbacks, mainly due to the use of 
intermittent devices, which are relatively noisy and incapable of 
operating at relatively high speed. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide a method of 
continuously supplying wrapping elements in sheet form, designed to 
overcome the aforementioned drawbacks. 
According to the present invention, there is provided a method of 
continuously feeding wrapping elements in sheet form to a user machine 
presenting an input conveyor in turn presenting a continuously-moving 
conveying surface for successively receiving said elements; the method 
comprising the steps of successively and continuously withdrawing said 
elements from an output end of a feedbox by means of respective gripping 
members; feeding said gripping members, together with the respective 
elements, along a given path; and releasing the elements onto said 
conveying surface; the method being characterized in that each gripping 
member presents a curved peripheral gripping surface for a respective said 
element; said withdrawing step being performed by withdrawing each element 
progressively from said output end by rolling the gripping surface of the 
respective gripping member along the output end; and said releasing step 
being performed by progressively releasing each element onto said 
conveying surface by rolling the gripping surface of the respective 
gripping member on the conveying surface. 
According to a preferred embodiment of the method according to the present 
invention, said gripping surface is a generally cylindrical surface 
presenting an axis; said withdrawing step comprising, for each said 
element, the substeps of moving the axis of the respective gripping member 
along a first trajectory parallel to said output end and at a first speed, 
and rotating the respective gripping member about said axis so as to 
impart to the respective gripping surface a second surface speed, about 
said axis, equal to twice said first speed. 
Preferably, said releasing step comprises, for each said element, the 
substeps of moving the axis of the respective gripping member along a 
second trajectory parallel to said conveying surface; and rotating the 
respective gripping member about said axis so as to impart to the 
respective gripping surface a third surface speed, about said axis, equal 
to a traveling speed of the conveying surface; said axis being moved along 
said second trajectory at a fourth speed equal to half said third speed.

DETAILED DESCRIPTION OF THE INVENTION 
Number 1 in FIG. 1 indicates a continuous supply unit for successively 
feeding wrapping elements 2 in sheet form to a roller 3 defining the input 
conveyor of a wrapping machine indicated as a whole by 4. Roller 3 
presents a substantially cylindrical conveying surface 3a coaxial with an 
axis 5 perpendicular to the FIG. 1 plane, and moving continuously at 
substantially constant angular speed W1 and anticlockwise about axis 5 to 
successively receive elements 2. 
Unit 1 comprises a feedbox 6 housing a stack 7 of elements 2 with their 
longer longitudinal axis parallel to axis 5, and which presents a 
substantially horizontal output end 8 for elements 2. Unit 1 also 
comprises at least one gripping member defined by a substantially 
cylindrical body 9 presenting an outer cylindrical gripping surface 10 
coaxial with an axis 11 parallel to axis 5, and which provides for 
withdrawing a respective element 2 from feedbox 6 and releasing it onto 
conveying surface 3a. In the FIG. 1 embodiment, unit 1 comprises three 
bodies 9 equally spaced about an axis 12 parallel to axis 5, and which are 
fed, in use, along a given path P at substantially constant angular speed 
W2 by a conveying device 13 forming part of unit 1. 
As shown more clearly in FIGS. 2 and 3, surface 10 of each body 9 presents 
a number of suction holes 14 arranged in at least three rows 15, 16, 17 
aligned with one another and parallel to respective axis 11; and holes 14 
communicate with a known suction device (not shown) for progressively 
withdrawing, by suction through holes 14, a respective element 2 from 
output end 8 of feedbox 6, and for retaining element 2 on surface 10. 
Device 13 provides for feeding each body 9 along path P, which extends in a 
circle about axis 12 and through a loading station 18 located at output 
end 8 of feedbox 6 and defining an input portion P1 of path P, and through 
an unloading station 19 located at roller 3 and defining an output portion 
P2 of path P. 
As shown in FIG. 3, device 13 is fitted to a frame 20 comprising two walls 
21, 22 perpendicular to axis 12; and a cup-shaped body 23 fitted outwards 
of and with its concavity facing wall 21. Cup-shaped body 23 in turn 
comprises an end wall 24 crosswise to axis 12; and a cylindrical wall 25 
coaxial with axis 12 and which, together with walls 24 and 21, defines a 
chamber 26. 
Conveying device 13 comprises a shaft 27 extending in rotary manner and 
coaxially with axis 12 through walls 21, 22, 24, and which is rotated 
about axis 12 at angular speed W2 by a belt transmission 28 located 
outside chamber 26 and comprising an output pulley 29 fitted to the free 
end 30 of shaft 27, and a toothed belt 31 looped about pulley 29 and about 
a further drive pulley (not shown). Device 13 also comprises a flange 32 
fitted to shaft 27 at wall 21 of frame 20 by means of a known joint 34; 
and a flange 33 fitted to shaft 27, between walls 21 and 22 and facing 
wall 22, by means of a further known joint 35. 
For each body 9, device 13 also comprises a cradle 36 supported by and in 
the space between flanges 32 and 33 so as to rotate about its own axis 37 
parallel to axis 11, and which is rotated by device 13 at angular speed W2 
about axis 12 so that respective axis 37 moves parallel to itself along 
path P. 
Cradle 36 presents two tubular end appendixes 38 and 39 coaxial with 
respective axis 37; appendix 38 is mounted for rotation through flange 32, 
via the interposition of a bearing 40, and projects partially inside 
chamber 26; and appendix 39 is mounted for rotation through flange 33, via 
the interposition of a further bearing 41. 
Cradle 36 also presents a cylindrical seat 42 coaxial with axis 37 and 
located in a substantially intermediate position between appendixes 38 and 
39, and supports respective body 9 inside seat 42 via the interposition of 
a shaft 43 extending coaxially with axis 11 through seat 42, and which is 
fitted in rotary manner to cradle 36 and in angularly-fixed manner to a 
bottom portion of body 9 on the opposite side of axis 37 to respective 
surface 10. 
Cradle 36 also presents a conduit 44 formed coaxially with axis 37 through 
appendix 39, and communicating at one end with said known suction device 
(not shown), and at the other end with a further conduit 45 formed 
coaxially with axis 37 inside body 9 to connect holes 14 to the suction 
device. 
Shaft 43 forms the output of an actuating device 46 for oscillating 
respective body 9 about axis 37, and which, in addition to shaft 43, also 
comprises a further shaft 47 mounted for rotation through appendix 38 and 
coaxial with axis 37, and a known gear train 48 interposed between shafts 
47 and 43 and housed inside a cavity 49 formed in cradle 36 in an 
intermediate position between appendix 38 and seat 42. 
Unit 1 also comprises a pair of control devices 50 and 51 housed inside 
chamber 26 and for respectively controlling the rotation speed W3 of 
bodies 9 about respective axes 11, and the angular position of bodies 9 
about respective axes 37. 
As shown in FIGS. 2 and 3, device 51 comprises a tappet 52 in turn 
comprising a tubular body 53 fitted to appendix 38 of cradle 36; an 
annular flange 54 integral with tubular body 53; a first set of three 
rollers 55 fitted for rotation to flange 54, facing wall 21, and equally 
spaced about axis 37; and a second set of three rollers 56 fitted for 
rotation to flange 54 on the opposite side of flange 54 to rollers 55, and 
offset angularly by a given spacing in relation to rollers 55. 
Device 51 also comprises a pair of known lobed cams 57 and 58 fitted side 
by side to wall 25 inside chamber 26, angularly offset in relation to each 
other by a length equal to said given spacing, and respectively engaged in 
rolling manner by rollers 55 and 56. More specifically, each cam 57, 58 is 
engaged by at least one respective roller 55, 56, and selectively by a 
second roller 55, 56, so that the number of rollers 55, 56 simultaneously 
contacting cams 57, 58 is always equal to three. 
Cams 57 and 58 present the same inner profile, and are so designed that, 
when, in use, axes 37 of bodies 9 travel along portion P1 of path P, 
respective axes 11 travel along a trajectory T1 parallel to and separated 
from output end 8 of feedbox 6 by a distance equal to the radius of 
curvature R of surface 10 of bodies 9; and, when, in use, axes 37 of 
bodies 9 travel along portion P2 of path P, respective axes 11 travel 
along a further, circular, trajectory T2 coaxial with axis 5 of roller 3 
and separated from surface 3a by a distance equal to radius R. 
Device 50 comprises a tappet 59, in turn comprising a plate 60 fitted 
integral with the free end of shaft 47 and crosswise to axis 37; a first 
set of three rollers 61 fitted for rotation to plate 60, facing wall 24, 
and equally spaced about axis 37; and a second set of three rollers 62 
fitted for rotation to plate 60 on the opposite side of plate 60 to 
rollers 61, and angularly offset by a further given spacing in relation to 
rollers 61. 
Device 50 also comprises a pair of known lobed cams 63 and 64 fitted side 
by side to wall 25 inside chamber 26 and between cam 57 and wall 24, 
angularly offset in relation to each other by a length equal to said 
further spacing, and respectively engaged in rolling manner by rollers 61 
and 62. More specifically, each cam 63, 64 is engaged by at least one 
respective roller 61, 62, and selectively by a second roller 61, 62, so 
that the number of rollers 61, 62 simultaneously contacting cams 63, 64 is 
always equal to three. 
Cams 63 and 64 present the same inner profile, and are so designed that, 
when, in use, axes 37 of bodies 9 travel along portion P1 of path P and 
respective axes 11 travel along trajectory T1 at a speed W4, the angular 
speed W3 of bodies 9 about respective axes 11 equals a value W3' equal to 
twice the value of W4, and is such as to permit respective surfaces 10 to 
roll along the output end 8 of feedbox 6; and, when, in use, axes 37 of 
bodies 9 travel along portion P2 of path P and respective axes 11 travel 
along trajectory T2 at a speed W5, the angular speed W3 of bodies 9 about 
respective axes 11 equals a value W3" equal to the value of speed W1, and 
is equal to twice the value of W5, i.e. is such as to permit respective 
surfaces 10 to roll along surface 3a of roller 3. 
Operation of unit 1 will now be described with reference to one body 9, and 
as of the instant in which conveying device 13 feeds said body 9 
continuously and at speed W2 through loading station 18 so that axis 37 of 
body 9 travels along portion P1 of path P. 
As axis 37 travels along portion P1, body 9 is rotated about axis 11 by 
control devices 50 and 51, so that surface 10 progressively engages and 
rolls along output end 8 of feedbox 6 and over and in contact with an 
element 2 at output end 8; rows 15, 16, 17 of holes 14 progressively 
contact element 2; and body 9 progressively withdraws element 2 from 
output end 8 of feedbox 6 starting from a portion 65 of the element 2 
itself. 
Alternatively, replacing conduit 45 with a known pneumatic distributor (not 
shown), each row 15, 16, 17 of holes 14, commencing with row 15, may be 
connected progressively to the suction device (not shown) as surface 10 
rolls along element 2, so that element 2 is only aspirated when contacted 
by holes 14. 
Device 50 controls the angular speed W3 of body 9 about axis 11 so that, as 
body 9 travels along portion P1, surface 10 rolls without sliding along 
output end 8; and, at the same time, device 51 controls the trajectory T1 
of axis 11 of body 9 so that trajectory T1 is maintained parallel to, and 
at a distance equal to radius R from, output end 8. 
Alternatively, the controls performed by devices 50 and 51 may be effected 
using only one known lobed cam (not shown) for each device 50, 51, as 
opposed to respective pairs of cams 63, 64 and 57, 58. In which case, 
tappets 59 and 52 will present five rollers (not shown) similar to and in 
place of rollers 61 and 55, and the inner profile of the two alternative 
lobed cams (not shown) will be such that the rollers (not shown) 
permanently contacting the inner profile are always two in number. Which 
solution is adopted substantially depends on the operating speed and 
precision required. 
Once element 2 is withdrawn from feedbox 6, conveying device 13 feeds body 
9, still continuously and at speed W2, along an intermediate portion P3 of 
path P3, located between portions P1 and P2 and along which axis 11 
travels along a trajectory T3 joining trajectories T1 and T2. 
On engaging unloading station 19, body 9 is so oriented by devices 50 and 
51 that surface 10 is positioned facing surface 3a. At which point, device 
13 feeds axis 35 of body 9 along portion P2, and devices 50 and 51 move 
body 9 so that surface 10 rolls along surface 3a. At the same time, the 
suction through holes 14 is cut of f, and element 2 is released onto 
surface 3a, commencing with a portion 66 on the opposite side of the 
longitudinal center line of element 2 to a portion 65. 
Alternatively, if conduit 45 is replaced by said known pneumatic 
distributor (not shown), the suction through holes 14 in rows 15, 16, 17 
may be cut off progressively, commencing with row 17, as surface 10 rolls 
along surface 3a. 
As body 9 travels through station 19, device 50 so regulates speed W3 of 
body 9 that any point on surface 10 presents the same tangential speed as 
any point on surface 3a. The speed correction imparted to body 9 as it 
travels through station 19 obviously differs from that imparted to it as 
it travels through station 18. In substantially the same way, device 51 
controls the trajectory T2 of axis 11, so that T2 is maintained parallel 
to surface 3a, at a distance equal to radius R from surface 3a, and 
coaxial with axis 5.