U.S. patent application number 10/946999 was filed with the patent office on 2005-03-24 for device for positioning the sheets into an introduction station of a processing machine.
This patent application is currently assigned to BOBST S.A.. Invention is credited to Cardillo, Marco, Lambercy, Edmond.
Application Number | 20050062220 10/946999 |
Document ID | / |
Family ID | 34280718 |
Filed Date | 2005-03-24 |
United States Patent
Application |
20050062220 |
Kind Code |
A1 |
Cardillo, Marco ; et
al. |
March 24, 2005 |
Device for positioning the sheets into an introduction station of a
processing machine
Abstract
This device for positioning the sheets comprises a feed table
with a drive for feeding the sheets. At least one front positioning
stop stops the leading edges of the sheets. A register for the
lateral position of the sheets. A device compares the lateral
position to a reference position. A transverse drive for the sheets
and a control applies the drive. The transverse drive comprises a
transverse slide arranged between the stop and the feed table. A
drive for the transverse slide is connected to the control. An
attachment device jointly attaches the sheet to the transverse
slide.
Inventors: |
Cardillo, Marco; (Lausanne,
CH) ; Lambercy, Edmond; (Chavannes-pres-Renens,
CH) |
Correspondence
Address: |
OSTROLENK FABER GERB & SOFFEN
1180 AVENUE OF THE AMERICAS
NEW YORK
NY
100368403
|
Assignee: |
BOBST S.A.
|
Family ID: |
34280718 |
Appl. No.: |
10/946999 |
Filed: |
September 22, 2004 |
Current U.S.
Class: |
271/236 |
Current CPC
Class: |
B65H 9/20 20130101; B65H
9/06 20130101; B65H 2403/51 20130101; B65H 2511/512 20130101; B65H
9/103 20130101; B65H 2511/512 20130101; B65H 2220/01 20130101 |
Class at
Publication: |
271/236 |
International
Class: |
B65H 007/02; B65H
009/00 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 23, 2003 |
CH |
01624/03 |
Claims
What is claimed is:
1. Device for positioning sheets into an introduction station of a
processing machine, comprising: a feed table; a feed drive for
moving the sheets in a feed direction over the table; at least one
front positioning stop to stop the leading edges of the sheets; a
register of the lateral position of the sheets on the table, a
comparing device for comparing the lateral position in the register
to a reference position; a transverse drive controllably driving
the sheets transversely on the table, and a control device for
applying the transverse drive with respect to the direction and the
space between the lateral registered position of the sheet and the
reference position and to stop the sheet when the sheet position is
in conformity with the reference position, the transverse drive
comprising a transverse slide disposed, along the feed direction,
between the stop and the feed table, a transverse motion control
operatively connected to the transverse drive for the transverse
slide; and an attachment device for selectively jointly attaching
the sheet onto the transverse slide.
2. Device according to claim 1, wherein the attachment device
jointly attaching the sheet with the transverse slide comprises,
respectively on both lateral sides of a plane sheet, at least one
pressing device operable for applying the sheet against the
transverse slide, and a moving device for perpendicularly moving
the pressing device with respect to the sheet across the feed
direction of the sheet.
3. Device according to one of the preceding claims, wherein the
moving device for moving the pressing device comprise two slides
perpendicularly arranged with respect to the sheet and across the
feed direction and kinematically linked to a drive mechanism of the
device for positioning.
4. Device according to claim 1, wherein the transverse slide has a
surface in contact with the sheets and the surface is of a material
with a high coefficient of friction with respect to the sheets.
5. Device according to claim 1, wherein a surface of the transverse
slide is in contact with the sheets and is a rough surface.
6. Device according to claim 3, further comprising cams fixedly
attached to a shaft kinematically linked to the drive of the feed
table; the attachment device comprises two swings, each swing
mounted about an horizontal axis, each swing having one respective
end that comes in contact with the respective lower ends of a
respective one of the vertical slides, wherein each slide comprises
an elastic element for applying any other respective end of the
swing against the cams.
7. Device according to claim 2, wherein each pressing device is
fixedly attached to a jack for bringing the pressing device in
contact with the transverse slide.
8. Device according to claim 1, further comprising two guiding
carriages on which the transverse slide is slidably mounted.
9. Device according claim 1, wherein each sheet has a print and a
lateral aligning mark related to the lateral position of the print,
the register of the lateral position of the sheets comprising an
optical reader for forming successive prints of the lateral
positions of the trajectories of the respective lateral aligning
marks with respect to the reference position.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention refers to a device for positioning
sheets into an introduction station of a processing machine,
comprising a feed table with drive means for the sheets, at least
one positioning front stop for stopping the leading edges of the
sheets, means for registering the lateral position of the sheets,
means for comparing the position to a reference position, means for
transversely driving the sheets and control means for controlling
the drive means dependent on the direction and the space between
the registered lateral position of the sheet and the reference
position and for stopping the sheet when the sheet meets with said
reference position.
[0002] In positioning devices usually used for machines that
process paperboard, solid board, corrugated board sheets, such as
converting presses comprising a plurality of stations, the
positioning of the sheets must be very accurate in both a
longitudinal direction and in a transverse direction at each
station they cross. To this end, the sheets are regularly infed by
a feeder towards the feed table, the sheets are shingled enabling
their seizing by a gripper bar and their conveying towards the
subsequent stations.
[0003] Each sheet is usually aligned on the feed table first
against front stops and then against lateral stops by means of
advance rollers or plastic foils supporting downwards on the table.
During processing of thin sheets, since the sheets are often
injured when they reach the stops, they can thus generate a
positioning error and their edges are marked.
[0004] The problem arising with the sheet positioning is also
especially delicate when the sheet is used in several operations,
such as printing, folding lines creasing, and diecutting, since
these operations must be carried out most exactly and each depends
on the preceding operation. In spite of all precautions, errors or
drifts in position of the processed portion with respect to the
leading and lateral edges of the sheet caused, for example, from
successive alignments at different locations of a sheet edge being
not exactly rectilinear, or from systematic alignments at the same
locations while leaving a mark. However, the diecutting of
pre-printed elements does not permit of any positioning error in
order to reach the desired quality of the manufactured product.
[0005] U.S. Pat. No. 6,264,196 discloses that when the sheet
reaches front stops mounted on a cylinder, it is seized by a
gripper of a gripping device arranged on a carriage that is
laterally held by two opposed compression springs. One of the
springs is coaxial to a rod and is compressed between one end of
the carriage and one rod shoulder. The end of the rod holds a
pressure roller that is actuated against a cam section, located
between two standby areas 41, 42. When the sheet reaches the front
stops, it is seized by the gripping device and the rod roller rests
in the standby area of the cam. Once the grippers close, the
pivoting cylinder drives the roller into a cam section while
laterally moving the carriage and thus the sheet itself. When a
detector registers the sheet edge, a brake is actuated to stop the
carriage. The remaining travel of the rod is absorbed by the
spring.
[0006] In the above mentioned patent, the register position is not
compared with a reference one for moving the sheet into one
direction and with a distance corresponding to the space between
the registered lateral position of the aligning mark and the
reference position. No comparison is effectively carried out, and
the original position of the sheet is not registered. One simply
moves the sheet until its lateral edge reaches the desired
position. The displacement applied by the cam remains the same and
is not related to the registered error, since that error is
unknown. One simply stops the carriage when the sheet edge is
registered by a detector. However, the front stops are not fixed,
but fixedly attached to the cylinder.
[0007] U.S. Pat. No. 4,989,855 describes a positioning device
wherein the stops are motorized in order to modify their position.
That device comprises means for registering an aligning mark on the
sheets to be aligned, comparing that mark with a reference position
and adjusting the stops for correcting the sheet position. Such a
device works like a common device and has the same risks, namely as
far as the lateral aligning is concerned.
[0008] EP 669,274 proposes an aligning device wherein the sheet to
be aligned is actuated against the front lays, and the sheet is
then laterally moved against side guides by means of a pull rod and
a pad between which the sheet is seized. The sheet motion is
stopped by side guides and the pull rod ends its motion sliding
with respect to the flat element. Such a device is more
particularly adapted for relatively rigid sheets such as corrugated
ones.
[0009] EP 1,044,908 describes a positioning device with no pad,
comprising a movable shelf with temporary fastening means for the
sheet to be aligned. On the one hand, the shelf is longitudinally
moved by a back-and-forth motion and, on the other hand, by
correction motions the shelf is moved about three vertical studs
each fixedly attached to a carriage, a central carriage sliding
into a longitudinal guide and two lateral carriages sliding into
transverse guides. The correction motions of the shelf are produced
by three linear motors controlled by opto-electronic registering
means. The correction is carried out during the sheet conveying by
the movable shelf, in order to drive the leading edge of the sheet
in the grippers of a gripper bar in an accurate reference position,
so that the temporary fastening means of the shelf can free the
sheet and the shelf can be brought back to its original position
for restarting with a new sheet. This device saves the time needed
for sheet alignment, thus appreciably increasing the processing
machine rate.
[0010] EP 1,151,833 discloses a closely related device, in which a
sheet gripping device is connected to the movable shelf by at least
one link comprising a plurality of levers forming a parallelogram
that can be put out of shape about an horizontal swiveling axis in
order to impede the arrival of a component of horizontal strength
issued from the opening levers of the temporary fastening grippers
of one sheet edge on the shelf.
[0011] Both of the above mentioned devices are very efficient in
their positioning accuracy as the rate increasing of said
positioned sheets are concerned. The alternative of an
uninterrupted positioning of the conveyed sheet effectively enables
saving the time needed for a common alignment. However, the
resulting productivity increase requires a huge investment. The
cost increase between a common registering system and an
uninterrupted positioning device like the ones described in EP
1,044,908 and EP 1,151,833 is appreciable and economically
justified only for some kind of machines.
[0012] EP 1,308,406 discloses a device for registering a lateral
edge of a sheet in an introduction station. One compares the
registered position of one lateral edge of the sheet with the
desired position, and produces a correction signal that generates
an adjusting signal transmitted to an adjusting member for moving
the lateral edge to the desired position. This operates directly on
the conveyed sheet with respect to the measured space between the
registered position and the desired position. On the other hand,
this document includes no detail about how to perform the
method.
SUMMARY OF THE INVENTION
[0013] The present invention has an aim to, at least partly
obviate, the usual drawbacks of common sheet aligning devices,
without considerably increased cost of the processing machine to
which the sheets positioning device is related.
[0014] To this end, the present invention relates to a sheet
positioning device into an introduction station of a processing
machine. This device for positioning the sheets comprises a feed
table with a drive for feeding the sheets. At least one front
positioning stop stops the leading edges of the sheets. A register
registers for the lateral position of the sheets. A device compares
the registered lateral position to a reference position. A
transverse drive drives the sheets and a control applies the drive.
The transverse drive comprises a transverse slide arranged between
the stop and the feed table. The drive for the transverse slide is
connected to the control. An attachment device jointly attaches the
sheet to the transverse slide.
[0015] The main advantage of the present invention that it joins
two aligning methods. To align the sheet leading edge, as with
common positioning devices, it uses front lays against which the
sheet is conveyed by the feed table, since the method of
positioning the leading edges of the sheets is reliable, simple and
has no appreciable drawback. Said front lays can be fixed or
adjustable. For lateral alignment, sheets driving means are
controlled by opto-electronic means, without using side guides that
have drawbacks, i.e. especially when processing flexible sheets.
Since the lateral alignment is achieved, as for common positioning
systems, after the leading edge of the sheet is aligned by the
front lays, the single movement applied to the sheet for laterally
aligning it is a rectilinear motion. This produces appreciable
simplification in the mechanical design or the electronic control,
with respect to a movable device according to three vertical axis,
like for abovementioned devices. Another important advantage of the
present invention is that the lateral alignment enables sheet
displacement in both directions, whereas a mechanical positioning
allows only to pull or to push, while moving the sheet in only one
direction.
[0016] Whereas devices for a single mechanical positioning only can
align the sheets depending on the sheet edge, the device according
to the invention can achieve the positioning according to a printed
aligning mark. It enables preventing errors between the print of
the sheets printed in reels and their edges sectionally diecut by
the reel, while using the print and not the diecut sheet edge as a
reference and the angle of the leading edge of the sheet to be
aligned can vary by several degrees with respect to the
perpendicular axis.
[0017] Further features and advantages of this invention will
become evident from the reading of the following description and
from the enclosed drawings illustrating, schematically and by way
of example, an embodiment of the device for positioning according
to the present invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] FIG. 1 is a perspective view illustrating the method of
positioning of the invention;
[0019] FIG. 2 is a transverse elevation view of the positioning
device;
[0020] FIG. 3 is a sectional view according to the line III-III of
FIG. 2;
[0021] FIG. 4 is a sectional view according to the line IV-IV of
FIG. 2;
[0022] FIG. 5 is the same view as FIG. 2, illustrating an
alternative;
[0023] FIG. 6 is a sectional view according to the line VI-VI of
FIG. 5;
[0024] FIG. 7 is a sectional and partially enlarged view of the
detail in the ring VII of FIG. 5;
[0025] FIG. 8 is a data-processing diagram of the control device of
the method of positioning.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0026] A method of positioning according to the invention is
illustrated in FIGS. 1 to 8. The sheet 1 to be aligned is conveyed
by a feed table T of a sheets processing machine, such as a die
cutting press, or a printing machine, wherein the sheet that just
went through a printing or die cutting operation must be accurately
positioned with a view to a subsequent operation on it, to ensure a
same reference position of the sheet for successive operations, so
that the print or die cutting position, for example, is not shifted
with respect to the preceding die cutting or printing
operation.
[0027] To this end, after the first operation is performed on the
sheet, the sheet 1 is conveyed in the direction of arrow F by the
feed table T against a plurality of front lays 2, whose position
could be adjustable. In this example, this operation is preferably
carried out by at least one pressure roller 3, controlled by a cam
or a pneumatic cylinder (not shown), pressing the sheet 1 against a
transverse slide 4, arranged in the feed direction between the feed
table T and the front lays 2. The pressure roller 3 could
alternatively be a gripping device, namely a suction pipe arranged
on the transverse slide and connected to a suction supply. A
photoelectric cell or a camera 5 is adapted to register a lateral
edge of the sheet 1 or, preferably, to register an aligning mark,
which has a position that is typically the one of the printing or
die cutting of said sheet 1 and to compare that position to a
reference one. The cell 5 is connected to an input of a control
station 6, which has one output connected to an actuator, namely a
linear motor 7 for driving the transverse slide 4 with respect to
the space between the measured lateral position of the sheet and
the reference position. The control station 6 produces a supply
current of a linear motor 7 dependent upon the direction in which
the linear motor 7 moves to bring the edge of the sheet 1 into the
reference position.
[0028] FIGS. 2 to 4 illustrate the device for positioning the
sheets into an introduction station of a processing machine. That
device comprises in its center a transverse support 8 fixedly
attached to the frame 9 of the processing machine which extends to
both ends of the transverse support 8. The support has in its
center a linear motor 7, which includes a U-shaped magnet rail 10
that is fastened by screws 11 to the transverse support 8. A reel
12, positioned into the magnet rail 10 of the linear motor 7, is
fastened to a movable section 13 of the linear motor 7 by screws
16. The reel 12 is connected to an output of the control station 6
(FIG. 1). The movable section 13 acts like a transverse slide. It
is connected to the transverse support 8 by two carriages 14a, 14b
arranged on both sides of the linear motor 10, 12. Each carriage
14a, 14b is coupled to two parallel guiding slides 15a, 15b (FIG.
3). The upper surface of the transverse slide, comprised of the
movable section 13, is fixedly attached to an aluminum section 17
covered with a material having a high friction coefficient such as
polyurethane, or which presents a roughened surface.
[0029] The positioning device also comprises a transverse profile
18 fixedly attached to two vertical slides 19a, 19b, mounted in two
vertical guides 20a, 20b fixedly attached to the frame 9. The
bottom of each vertical slide 19a, 19b is pressed by a spring 21a,
21b against a roller 22a, 22b, assembled swiveling at the end of an
arm of a swing 23a, 23b rotatable in its center on the frame 9.
Another roller, of which only the roller 24a is shown on FIG. 4, is
assembled swiveling at the other arm end of each swing 23a, 23b.
The rollers of the swings 23a, 23b are pressed against two related
cams, of which only the cam 25a is shown on FIG. 4, are fixedly
attached to a control shaft 26 kinematically linked to the drive
mechanism (not shown) of the processing machine for the sheets
1.
[0030] Two pairs of pressure rollers 27a, 27b are freely swiveling
about their pair axis perpendicular to the transverse section 18,
i.e. parallel to the advance direction F of the sheet 1 and fixedly
attached to two supports 28a, respectively 28b. Each support 28a,
28b comprise two adjusting units 29a, 29b, 30a, 30b to adjust the
height, respectively the lateral position of each support 28a,
28b.
[0031] Each turn about the control shaft 26 is related to a working
cycle of the positioning device during which the cams 25a, 25b are
pivoting the swings 23a, 23b, driving thus the rollers 27a, 27b
downwards against the aluminum section 17, seizing the sheet 1
between said section 17 and the rollers 27a, 27b after the sheet is
supported against the front lays 2. The register cell 5 registers
the position of the lateral edge of the sheet 1 or of an aligning
mark on the sheet and sends the value as well as the direction of
the measured space to the control station 6. The latter sends an
electric current to the reel 12 of the linear motor for moving the
transverse slide 13, forming the movable part of the linear motor,
in the desired direction until the position registered by the
register cell refers about the lateral position of the sheet 1 as
being related to the reference position.
[0032] The operation of lateral displacement of the sheet 1 by the
linear motor is achieved in synchronism with the rotation of the
control shaft 26, so that when the correction is over, the cams
25a, 25b, connected to the control shaft 26, are swiveling the
swings 23a, 23b (FIG. 4) in the anticlockwise direction, while
raising the slides 19a, 19b and the rollers 27a, 27b. The sheet 1
is thus free and the cycle can re-start with a new sheet 1. The
means used for stripping the positioned sheet comprise a common
gripper bar. The latter is not shown as it is not mentioned in the
present invention and is of no use for its understanding.
[0033] According to the alternative of the device illustrated on
FIGS. 5 to 7, instead of joining the transverse section 18 to
vertical slides 19a, 19b, that alternative comprises a transverse
section 31 fixedly attached by its both ends to the frame 9. Each
pair of pressure rollers or shoes 27a, 27b is then fixedly attached
to the rod of a cylinder 32a, 32b, as well as to two guide rods
33a, 33b, arranged sliding inside the cylinder 32a, 32b, so that
the rollers or shoes 27a, 27b are applied against the sheet 1
supporting on the movable section 13 of the linear motor at the
time of its lateral alignment by means of the cylinders 32a, 32b.
Such an alternative is more advantageous than the embodiment
illustrated by FIG. 2, since it is less expensive.
[0034] Although the present invention has been described in
relation to particular embodiments thereof, many other variations
and modifications and other uses will become apparent to those
skilled in the art. It is preferred, therefore, that the present
invention be limited not by the specific disclosure herein, but
only by the appended claims.
* * * * *