U.S. patent application number 12/200938 was filed with the patent office on 2009-03-05 for sheet feeder.
This patent application is currently assigned to RAUTE OYJ. Invention is credited to Peter William GIBSON.
Application Number | 20090057980 12/200938 |
Document ID | / |
Family ID | 43401408 |
Filed Date | 2009-03-05 |
United States Patent
Application |
20090057980 |
Kind Code |
A1 |
GIBSON; Peter William |
March 5, 2009 |
SHEET FEEDER
Abstract
The invention concerns an apparatus for forward transferring
sheet-like objects from a stack, said apparatus including separate
lifting elements gripping by suction to the upper surface of the
sheet-like object situated top-most on the stack. The gripping
elements are positioned in a row extending over the stack of the
sheet-like objects in transversal direction with respect to the
forward direction of the sheet-like object. The suction effect of
the lifting elements is individually controlled by means of a
control device including a light source creating a substantially
line-shaped illumination pattern over the top of the stack. The
illumination of the light source is focused substantially parallel
to the lifting element row, at an inclined angle to the surface
plane of the sheet stack. Camera means for observing the
illumination pattern forwards information about the uniformity of
the uppermost layer of the stack for controlling the gripping
elements.
Inventors: |
GIBSON; Peter William;
(Maple Ridge, CA) |
Correspondence
Address: |
YOUNG & THOMPSON
209 Madison Street, Suite 500
ALEXANDRIA
VA
22314
US
|
Assignee: |
RAUTE OYJ
NASTOLA
FI
|
Family ID: |
43401408 |
Appl. No.: |
12/200938 |
Filed: |
August 29, 2008 |
Current U.S.
Class: |
271/3.09 ;
271/3.11 |
Current CPC
Class: |
B65G 59/04 20130101;
B65H 3/0891 20130101; B65H 2515/342 20130101; B65H 2553/42
20130101; B65H 2406/362 20130101; B65H 2515/60 20130101; B65H
2515/342 20130101; B65H 3/0816 20130101; B65H 2515/60 20130101;
B65H 2557/51 20130101; B65H 7/14 20130101; B65H 2511/12 20130101;
B65G 2203/041 20130101; B65H 2511/20 20130101; B65H 2701/1938
20130101; B65H 2511/12 20130101; B65H 2511/20 20130101; B65H
2515/342 20130101; B65G 59/045 20130101; B65H 2220/01 20130101;
B65H 2220/02 20130101; B65H 2220/02 20130101; B65H 2220/01
20130101; B65H 2220/01 20130101 |
Class at
Publication: |
271/3.09 ;
271/3.11 |
International
Class: |
B65H 5/22 20060101
B65H005/22; B65H 7/14 20060101 B65H007/14 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 29, 2007 |
FI |
20070654 |
Claims
1. An apparatus for forwarding transfer sheet-like objects from a
stack, said apparatus including separate lifting elements
positioned in a row extending over the stack in transversal
direction with respect to a forwarding transfer direction from the
stack, said lifting elements being connected to a vacuum means and
equipped with an opening/closing/means for each element for
releasable gripping by suction to the upper surface of the
sheet-like object lying top-most in the stack and to be transferred
from the stack, and transfer elements for transferring the lifted
sheet-like object from the stack, wherein the apparatus further
includes a control device including a light source creating a
substantially line-shaped illumination pattern focused
substantially parallel to the lifting element row, at an inclined
angle to the plane of the top surface of the sheet stack, and a
camera means for observing the illumination pattern, the gripping
operation of the lifting elements being individually controlled by
means of said control device
2. The apparatus according to claim 1, wherein the lifting elements
are located adjacent to each other and form a suction line
extending in transversal direction substantially over the total
width of the stack.
3. The apparatus according to claim 1, wherein the lifting means
comprise a slide actuator means for controllably opening and
closing the suction effect, respectively.
4. The apparatus according to claim 2, wherein the lifting means
comprise a slide actuator means for controllably opening and
closing the suction effect, respectively.
Description
[0001] The present invention concerns an apparatus for transferring
sheet-like objects from a stack formed thereof. Especially the
invention concerns an apparatus for transferring veneer sheets and
the like.
[0002] Equipment based on suction gripping devices is used for this
purpose, for gripping the upper surface of the uppermost veneer
sheet in the stack and lifting the sheet into contact with
transferring devices. The transferring devices are usually
horizontal rolls cooperating with the suction gripping devices,
having rotating motion parallel to the intended transfer direction.
The sheets to be transferred are lifted one by one with the suction
gripping devices into contact with the mantle surface of the rolls,
and kept in contact with the mantle surface of the rolls for
providing the transferring event.
[0003] The suction gripping devices are in principle single suction
nozzles arranged in a row extending substantially over the stack in
transversal direction with respect to the intended transfer
direction. The device operates without problems with full-sized
veneer sheets, but problems are caused by random veneer layers
consisting of narrower sheets than the sheets with full width.
[0004] It has been tried to compile these random sheet layers so,
that the random width sheets are side by side in the layer and
cover substantially the same area in the stack as the sheet with
full width. At this kind of a stack layer, the transferring device
known in the art in general still operates without problems, in
other words, the suction gripping devices get a grip on all sheets
of the uppermost layer, and they are moved together from the stack
forward, usually to the drying apparatus of veneer.
[0005] In spite of careful compiling of the layers in the stack,
whether made manually or by machine, there are mistakes occurring
when compiling the layers, as a result of which there can be sheets
in a layer more or less overlapping each other Overlapping sheets
are also forwarded, when uppermost on the stack, supported by the
suction gripping devices, at least partly overlapping. A part of
the sheets taken along with the suction gripping devices may loosen
too early, and fall back onto the stack, as a result of which the
top layer of the stack will be mixed. Due to the overlapping, the
veneer sheets that hold on cause problems for the apparatus
handling the veneers in the next step, like in the drier, as
blockages that are difficult to unblock, incomplete drying etc.
[0006] A single random veneer left or fallen in the stack follows
on top of the next full veneer in the next lifting step causing the
overlapping problem.
[0007] With the apparatus of the present invention, these problems
have been significantly solved.
[0008] The basic structure of the apparatus according to the
invention is formed by an apparatus comprising, as known in the
art, separate lifting elements gripping by suction to the upper
surface of the sheet-like object to be transferred, said lifting
elements being located in a row extending over the stack of the
sheet-like objects, in transversal direction with respect to the
transfer direction of the object, and transfer means for
transferring the lifted sheet-like object. According to a
characteristic of the invention, the suction effect of the lifting
elements can be individually controlled by means of a control
device including a light source creating a substantially
line-formed illumination pattern, the illumination being focused
substantially parallel with the lifting element row, at an inclined
angle in respect to the plane of the surface of the sheet stack,
and a camera means for observing the illumination pattern.
[0009] The invention will be described in more detail in the
following with reference to the enclosed drawing, wherein
[0010] FIG. 1 shows the apparatus according to the invention for
transferring veneer sheets from a stack,
[0011] FIG. 2 shows the apparatus of the invention at the operating
stage, and
[0012] FIG. 3 illustrates the effect of the control of suction
lifting devices on the operation of the device.
[0013] FIG. 1 shows schematically a veneer stack 10, where veneer
sheets are being removed from, layer by layer, to be forwarded to
further processing, like drier. The veneer layer is lifted from the
stack by means of suction lifting devices 8 operative in the
vicinity of the upper surface of the veneers. When the suction
effect 4 is active, the suction lifting devices grip the veneer or
veneers of the uppermost veneer layer and bring them into contact
with the rolls 14, keeping the lifted veneer or veneers in contact
with the rolls. The rolls have rotational motion in the transfer
direction, and they take the veneer or veneers in the intended
transfer direction, for example to be transferred by the rolls 5.
FIG. 1 shows a typical problem situation that can occur in the
stack 10 in cases, where there is a layer composed of random width
veneer sheets. The veneer sheets are partly overlapping. Thus, an
apparatus having the construction of prior art would probably face
an operating disturbance.
[0014] To avoid the operating disturbance, the basic apparatus is
complemented with an additional device according to the present
invention, by means of which the operation of the suction lifting
devices can be controlled in an appropriate way.
[0015] Each of the suction lifting devices 8 is equipped with
respective closing means that in the described embodiment is formed
by a slide 7 and an actuator 6, like a pneumatic cylinder-piston
device. With the closing means, each suction lifting device can be
connected to or disconnected from the suction effect 4. Individual
operation of the actuators is controlled by an activating device
being able to make logical decisions based on the received
information. The activating device is not shown in the figure. This
kind of a device is well known to a person skilled in the art, and
there is no need to describe its operation in detail in this
connection. The activating device receives the required information
from the camera means 1 included in the apparatus. The camera means
is a matrix camera known in the art, having a suitable resolution
for the task. The visibility range of the camera reaches over the
veneer stack, and is in the perpendicular direction wide enough to
observe the illumination pattern focused onto the surface of the
veneer stack.
[0016] The illumination pattern is focused onto the surface of the
veneer stack line-shaped, with a strong light source 2, suitable
for this purpose being a laser light source. The illumination is
focused onto the surface of the stack at an inclined angle of
20.degree. to 45.degree., for example. If there happens to be
veneer sheets positioned overlapping on the surface of the stack,
the beam of light first meets the sheets locating highest on the
stack, like sheets 11 and 12 in FIG. 1. The sheets locating lower
get to the beam of light at a longer distance from the light source
2, whereby the illumination pattern formed onto the surface of the
stack is correspondingly stepped. This stepness will be discovered
by the camera 2. It gives information on the location of the steps
of the illumination pattern in the transfer direction of the veneer
sheets, and the extension of each step in the direction of the
illumination pattern. Based on this information, the activation
device of the suction lifting devices makes logical decisions,
which of the veneer sheets (11 and 12) is/are uppermost in the
stack, and what is their location in the stack, in the transversal
direction with respect to the transfer direction. Based on these
decisions, the activating device controls the closing means 8 to
open only at the veneer sheets lying uppermost in the stack,
whereby only those are taken to be transferred with the rolls 14
and are removed from the stack, FIG. 2.
[0017] The capacity of the apparatus further processing the veneers
will be underutilized per each such lifting turn, but there will be
no overlapping veneer sheets in the apparatus, and no veneer sheets
drop back on top of the veneer stack. Correspondingly, the problems
being caused by the sources in question will be avoided in the
operation of the apparatus.
* * * * *