Device for parting and successively feeding stacked elements of sheet material to a user machine

A device wherein at least one feedbox housing a stack of sheet elements presents a first and second wall parallel to each other, and an actuating device for moving the two walls in relation to and parallel to each other, so as to define a channel varying in width between a maximum and minimum value; the section of the channel at maximum width being approximately equal to but no smaller than the surface of the sheet element.

BACKGROUND OF THE INVENTION 
The present invention relates to a device for parting and successively 
feeding stacked elements of sheet material to a user machine. 
In the following description, specific reference is made, purely by way of 
example, to a device for parting and feeding stacked, particularly 
die-cut, labels to a user machine, particularly a packing machine. 
On known devices of the aforementioned type, the labels are usually placed 
inside a normally tubular feedbox with an open output end from which the 
labels are withdrawn successively by a withdrawal device and with the aid 
of a parting device. Known parting devices are normally mounted on the 
feedbox, and generally comprise a roller or similar movable member, which, 
when brought into contact with the lateral surface of the stack of labels 
inside the feedbox, provides for successively deforming and so separating 
the labels. 
Despite effectively separating the stacked labels, known parting devices of 
the aforementioned type invariably result in a certain amount of damage to 
at least one lateral edge of the labels. What is more, the movable parting 
member requires the use of a complex, high-cost activating device. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide a device for parting 
and successively feeding stacked elements of sheet material to a user 
machine, designed to overcome the aforementioned drawbacks. 
According to the present invention, there is provided a device for parting 
and successively feeding stacked elements of sheet material to a user 
machine, the device comprising at least one feedbox designed to receive a 
stack of said elements; characterized by the fact that said feedbox 
comprises a first and second wall parallel to each other; and that 
actuating means are provided for moving said two walls, in relation to and 
parallel to each other, between a first and second relative position, and 
so as to define a channel varying in width between a maximum and minimum 
value; the section of the channel, when said width is maximum, being 
approximately equal to but no smaller than the surface of said element.

DETAILED DESCRIPTION OF THE INVENTION 
Number 1 in FIG. 1 indicates a feedbox device for feeding sheet material, 
in particular labels 2, to a production machine (not shown) featuring a 
device 3 for successively withdrawing labels 2 from device 1. 
In the example shown, device 1 comprises a carriage 4 supporting two 
feedboxes 5, 6 designed to receive respective stacks 7, 8 of labels 2; and 
an actuating device 9 for moving carriage 4 back and forth and so moving 
each feedbox 5, 6 along a guide 10 and to and from a withdrawal station 11 
wherein feedbox 5, 6 cooperates with withdrawal device 3. 
Each feedbox 5, 6 comprises a first fixed wall 12 integral with carriage 4; 
a second wall 13 extending parallel to wall 12 and defining, with wall 12, 
a channel 14 for housing stack 7, 8 and conveying respective labels 2 to 
withdrawal device 3; and two pairs of intermediate cross members 15, each 
of which is a crank connected to walls 12 and 13 by respective hinges 16, 
so as to define, with walls 12 and 13, an articulated quadrilateral. 
On the opposite side to that facing withdrawal device 3, walls 12 and 13 
define an opening 17 for inserting labels 2 inside channel 14; and, on the 
side facing withdrawal device 3, walls 12 and 13 terminate with respective 
appendixes 18 and 19 arranged facing each other and defining an opening 20 
through which labels 2 are withdrawn from channel 14. 
Wall 13 of each feedbox 5, 6 is connected to a respective adjusting device 
21 supported in a fixed position on a frame (not shown), and which 
provides for moving wall 13 in relation to wall 12, and between a first or 
loading position (FIG. 2) wherein cross members 15 are perpendicular to 
walls 12 and 13, and channel 14 is of maximum width with a section 
approximately equal to but no smaller than that of respective undeformed 
stack 7, 8; and a second or operating position (FIG. 3) wherein cross 
members 15 and the plane of output opening 20 slope in relation to walls 
12 and 13. 
With reference to FIGS. 2 and 3, each device 21 comprises a guide 22 
defined by two rods extending parallel to channel 14 of respective feedbox 
5, 6; a slide 23 connected to guide 22; and an actuating cylinder 24 
connected to slide 23, for moving it back and forth along guide 22. Each 
device 21 also comprises a fork 25 integral with slide 23 and facing wall 
13, so as to define a channel 26 extending perpendicular to guide 22 and 
the FIGS. 2 and 3 plane, and parallel to guide 10, and which is engaged by 
a roller 27 mounted for rotation on a pin 28 extending perpendicularly 
from wall 13 and outwards in relation to channel 14. When roller 27 of 
wall 13 engages fork 25, and slide 23 is moved along guide 22 from the 
backup position in FIG. 2 to the forward position in FIG. 3, respective 
wall 13 is moved from said loading to said operating position. 
When slide 23 is set to the forward position, channel 26 of each fork 25 is 
aligned with a similar channel 29 of a fixed guide 30 extending between 
the two devices 21 and parallel to guide 10, and designed to receive 
rollers 27 when respective walls 13 are set to the operating position. 
With reference to FIGS. 1 to 3, guide 10 of actuating device 9 is defined 
by two parallel rods 31, the ends of which, on either side of adjusting 
devices 21, are supported on two fixed brackets 32 and 33. Bracket 33 also 
supports the body of an actuator 34, the output rod 35 of which extends 
through bracket 33 and parallel to rods 31, and presents its free end 
connected to carriage 4, which presents two through holes 36, each engaged 
in sliding manner by a respective rod 31. 
As shown in FIG. 1, actuator 34 provides for moving feedboxes 5 and 6 
between withdrawal station 11, common to both feedboxes 5 and 6, and 
respective loading stations 37 and 38 located symmetrically on either side 
of station 11. More specifically, carriage 4 is so sized that, when one of 
feedboxes 5, 6 is moved into withdrawal station 11, the other is moved 
into respective loading station 37, 38. Moreover, by virtue of channel 29 
of fixed guide 30 only being aligned with channel 26 of fork 25 when 
respective wall 13 is in the operating position, each feedbox 5, 6 may 
only be moved to and from withdrawal station 11 when respective wall 13 is 
in said operating position. 
Inside withdrawal station 11, opening 20 of feedbox 5, 6 is positioned 
facing the outer surface of a known endless suction belt 39 forming part 
of withdrawal device 3, which also comprises two guide rollers 40 and 41 
(one of which is powered) supporting belt 39 and rotating about respective 
axes 42 and 43 perpendicular to guide 10 and to the FIG. 1 plane. Rollers 
40 and 41 divide belt 39 into a delivery branch 44 facing feedboxes 5 and 
6, and a return branch 45. Roller 41 is supported for rotation on a fork 
46 connected integral with the output rod 47 of an actuator 48, and which 
is moved, by actuator 48, between a backup position (dotted line in FIG. 
1) and a forward position (continuous line in FIG. 2) wherein branch 44 of 
belt 39 extends through withdrawal station 11, and provides for engaging, 
by suction, the bottom label 2 in stack 7, 8 inside feedbox 5, 6 in 
withdrawal station 11. 
In actual use, when carriage 4 of actuating device 9 is set to a first 
limit position (FIG. 2) wherein feedbox 6 is in loading station 38, 
feedbox 5 is in withdrawal station 11, roller 27 of feedbox 6 engages fork 
25 of respective adjusting device 21, and slide 23 of device 21 is in the 
backup position, channel 14 of feedbox 6 is of maximum width, thus 
enabling stack 8 of labels 2 to be inserted inside feedbox 6. 
When inserted inside channel 14, stack 8 is in the form of a rectangular 
parallelogram with labels 2 arranged perpendicular to walls 12 and 13. As 
labels 2 are normally die-cut, the lateral edges of the labels invariably 
cling together, thus making successive withdrawal of the labels through 
opening 20 extremely difficult, if the labels, pushed towards opening 20 
by a piston 14a, are not first separated by moving respective slide 23 
into the forward position. This in fact provides for narrowing channel 14, 
so that labels 2 slide one on top of the other into the inclined position 
shown in FIG. 3, wherein labels 2, still parallel to opening 20, are 
arranged parallel to delivery branch 44 of belt 39 and to labels 2 in 
stack 7 in withdrawal station 11. 
When labels 2 in stack 7 run out, a sensor (not shown) provides for 
operating actuator 34, which moves carriage 4 into a second limit position 
(dotted line in FIG. 1) wherein feedbox 5 is in loading station 37, 
respective roller 27 engages fork 25 of respective adjusting device 21, 
feedbox 6 is in withdrawal station 11, and respective roller 27 engages 
channel 29 of fixed guide 30 so as to maintain respective wall 13 in the 
operating position. 
At this point, a fresh stack 7 of labels 2 is loaded into feedbox 5, while 
labels 2 in stack 8 are withdrawn successively through opening 20 by 
device 3, the belt 39 of which is moved forward in steps and, at each 
step, is pushed by actuator 48 towards opening 20 so as to engage label 2, 
and then detached from opening 20 so as to withdraw label 2 from feedbox 
6. 
The above cycle is repeated until labels 2 in stack 8 run out, and actuator 
34 is again operated for moving carriage 4 into the other limit position. 
According to a variation not shown, actuating device 9 may of course be 
dispensed with, together with one of feedboxes 5, 6 and one of adjusting 
devices 21, and the remaining feedbox 5, 6 may be mounted, together with 
adjusting device 21, in a fixed position in withdrawal station 11. In this 
case, the user machine (not shown) must of course be stopped temporarily 
for inserting the stack of labels 2 inside the single feedbox and 
subsequently parting labels 2. 
The embodiment shown in FIGS. 4 and 5 relates to a device 49 similar to 
device 1, and the component parts of which are indicated where possible 
using the same numbering system. 
On device 49, carriage 4 is replaced by an indexing fixture 50 fitted 
integral with walls 12 of a number of feedboxes 51, and which is rotated 
about axis 52 by an activating device 50a (shown partially), so as to 
successively feed feedboxes 51 through a loading station 53 and a 
withdrawal station 11. Feedboxes 51 are substantially identical to 
feedboxes 5 and 6, and each presents a roller 27 rolling inside the 
channel 54 of a drum type cam 55 substituting for adjusting devices 21 and 
so formed as to move wall 13 of each feedbox 51 into the loading position 
at loading station 53, and into the operating position at withdrawal 
station 11.