U.S. patent number 3,703,281 [Application Number 05/171,167] was granted by the patent office on 1972-11-21 for sheet feeding apparatus having gripper control, for use with printing machines.
This patent grant is currently assigned to Maschinenfabrik Augsburg-Nurnberg AG. Invention is credited to Oskar Liebert, Klaus Theilacker.
United States Patent |
3,703,281 |
Liebert , et al. |
November 21, 1972 |
SHEET FEEDING APPARATUS HAVING GRIPPER CONTROL, FOR USE WITH
PRINTING MACHINES
Abstract
The grippers on a sheet feeding apparatus from a printing
machine are controlled by having a follower contacting the leading
cam formed as a parallelogram - shiftable track, suspended on
leading and trailing swing arms of equal length, having one end
each pivotable about leading and trailing points, the shiftable
track being arranged at shallow angle with respect to the center of
the chain conveyer; and a trailing cam, formed as a swingable
segmental-like element swinging about a pivot point and having a
leading edge thereof located approximately in the prolongation of a
line connecting the pivot point thereof and the suspension point of
the trailing swing arm of the shiftable track. The trailing cam
means being formed to have a leading edge outline which matches
substantially with the trailing edge outline of the leading cam, so
that the gripper control follower will be smoothly engaged by both
leading and trailing cams to release sheets carried by the
grippers, and the release position is readily adjustable for
various sizes of printed material.
Inventors: |
Liebert; Oskar (Westheim,
DT), Theilacker; Klaus (Neusass, DT) |
Assignee: |
Maschinenfabrik Augsburg-Nurnberg
AG (Augsburg, DT)
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Family
ID: |
5779894 |
Appl.
No.: |
05/171,167 |
Filed: |
August 12, 1971 |
Foreign Application Priority Data
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Aug 17, 1970 [DT] |
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P 20 40 670.6 |
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Current U.S.
Class: |
271/206 |
Current CPC
Class: |
B65H
29/047 (20130101); B65H 29/041 (20130101); B65H
2701/176 (20130101) |
Current International
Class: |
B65H
29/04 (20060101); B65H 29/02 (20060101); B65h
029/28 () |
Field of
Search: |
;271/79,82,85,68
;198/180 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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818,365 |
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Sep 1951 |
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DT |
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1,219,045 |
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Jun 1966 |
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DT |
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Primary Examiner: Blunk; Evon C.
Assistant Examiner: Stoner, Jr.; Bruce H.
Claims
We claim:
1. In a sheet transport apparatus having a chain conveyor (2),
gripper means (3, 4) secured to the chain conveyor, control means
for said grippers and a follower (5) adapted to be contacted by
said control means, said control means comprising
leading cam means (6) being formed as a parallelogram-shiftable
track (6') and leading and trailing swing arms (8,9) suspending
said shiftable track (6'), said swing arms being of equal length
and having one end each pivotable about leading and trailing points
(14', 12), the shiftable track being arranged at a shallow angle
with respect to the center line of the chain conveyor (2);
and trailing cam means (7) formed as a swingable segmental-like
element swinging about a pivot point (12) and having a leading edge
thereof located approximately in the prolongation of a line
connecting said pivot point thereof (12) and the suspension point
(14) of the trailing swingable arm with the shiftable track
(6');
the trailing cam means (7) being formed to have an outline merging
smoothly with the outline of the leading cam means (6).
2. Apparatus according to claim 1 wherein the segmental-like
element of the trailing cam means has a control edge which is
eccentric with respect to its pivot point (12) the radial distance
of the trailing cam means decreasing in direction of movement of
the follower (5).
3. Apparatus according to claim 1 wherein the leading cam means (6)
partly overlap the trailing cam means (7), to form a combined
camming surface (15), the combined camming surface having a lesser
radius than the radius of the trailing cam means.
4. Apparatus according to claim 1 wherein said swing arms are
formed as double arm cranks (8, 9);
and adjustment means (11) engaging one of said cranks at the end
thereof not connected to the shiftable track.
5. Apparatus according to claim 4 wherein the adjustment means
comprises a control rod (11) connected to one of said cranks, said
control rod being shiftable in position in dependence on machine
speed.
6. Apparatus according to claim 4 wherein the adjustment means
comprises a control rod (11) connected to one of said cranks;
and means (31) sensing machine speed and connected to shift said
control rod in dependence on sensed machine speed.
7. Apparatus according to claim 4 wherein one of the crank arms
(10) is formed with limit means (17, 18) to limit the extent of
movement thereof.
8. Apparatus according to claim 7 wherein said limit means
comprises a pin engaging an elongated slot.
9. Apparatus according to claim 1 wherein the angle of swing of
said swing arms is about 40.degree..
10. Apparatus according to claim 1 wherein the shiftable track and
the trailing cam means are formed as interdigited elements.
11. Apparatus according to claim 1 wherein the pivot point (12) of
the trailing swing arm (8) and the pivot point (12) of the trailing
cam means (7) are coaxial.
12. Apparatus according to claim 1 including a tension spring
interconnecting the arms to counteract play in the swing and pivots
points thereof.
Description
The present invention relates to printing machines, and more
particularly to sheet feeding apparatus in connection with printing
machines to transport sheets which have been printed on the
machines to a stack.
Sheet transporting apparatus for use with printing machines has
been proposed in which a chain carries grippers which, when they
reach the position of the stack, engage a control surface or a
camming surface, to release the sheets which they grip. Usually a
follower wheel is provided to engage this control surface; an
illustration of such a device is found in U.S. Pat. No. 2,631,038.
Controlling the grippers by means of a cam surface consisting of
two parts has already been proposed (see German Pat. No.
1,219,045--to which British Pat. No. 1,151,894 corresponds). The
leading edge of the cam, with respect to the travel of feed, is
interconnected with the trailing cam portion, which is circular, by
means of a pivot which can slide along a slit with respect to the
sprocket wheel, so that, by means of an intervening link to the
sprocket wheel, the position of the trailing edge curve can be
matched to the respective position of the leading edge cam curve.
This is a complicated arrangement and can be adjusted only over
very small limits.
Another known control for the grippers (see German Pat. No.
818,365) utilizes a control cam having a leading portion which is
straight and a bent, bow-shaped trailing portion. The control cam
can be pivoted by means of a hydraulic transmission, so that the
control roll of the grippers engages the cam surface sooner, or
later, as desired. This arrangement, also, is capable of adjustment
only over narrow limits and has the disadvantage that the angle of
attack with respect to the roll changes.
Single-element straight control cams can be used only when the
sprocket wheel for the transport arrangement is beyond the
receiving stack, since, otherwise, there is danger that the sheet
which is to be stacked is caught again by the grippers which are in
the process of reclosing.
It is an object of the present invention to provide a sheet
transport arrangement for use with printing machines in which the
grippers can be controlled over wide ranges, that is, to provide a
wide range of adjustment for the leading edge of the control cam,
while maintaining an essentially even, or constant angle of attack
of the leading edge with respect to the gripper controller itself
throughout this adjustment range.
SUBJECT MATTER OF THE PRESENT INVENTION
Briefly, the gripper control for the sheet transport apparatus of
the machine includes a leading cam which is formed as a
parallelogram - shiftable track, adapted to be engaged by a gripper
control follower, which controls the gripper opening. The
parallelogram - shiftable track is suspended on a pair of swing
arms of equal length, one end each being pivoted about leading and
trailing points. The shiftable track is so arranged that it has a
shallow angle with respect to the center line of the transport
conveyor. A trailing cam as provided is formed as a swingable
segment-like element, swingable about a pivot point, and having a
leading edge located approximately in the prolongation of a line
connecting the pivot point of the segment-like element and the
suspension point of the trailing swing arm of the shiftable track.
The trailing cam is formed to have an outline merging smoothly with
the outline of the leading cam means, so that the gripper control
is smoothly engaged by the overall, articulated cam arrangement
formed of the leading and trailing cam means.
The apparatus provides wide adjustment of the opening of the
grippers, depending on paper quality, printing speed, paper
thicknesses and other perameters. The inclination of the leading
curve with respect to the gripper control will be constant, due to
the parallelogram attachment, and thus hard impact of the control
followers on the grippers with the gripper opening cams is avoided.
The trailing ends of the leading cam are preferably formed to
surround the portion of the trailing cam itself so that the entire
running width of the follower rollers on the grippers can be
completely utilized in the region of the greatest application of
force thereon, that is, just upon opening of the grippers. The
arrangement can be simply manufactured and is, therefore,
inexpensive.
The invention will be described by way of example with reference to
the accompanying drawings, wherein:
FIG. 1 is a highly schematic side view of the control for the
transport grippers;
FIG. 2 is a top view of the transport gripper control, partly
developed in the direction of the arrow A of FIG. 1.
Sheets are to be stacked on a stack 1, located beyond the sheet
transport chains. They are transported by means of a gripper
arrangement 3, secured to endless chains 2, and removing the sheets
from the printing presses, in the direction of the arrow of FIG. 1.
Such grippers and sheet removal conveyors are well known in the
art. The gripper shaft 4 is connected to a torsion bar suspension
control follower roll 5, which cooperates with a leading cam
portion 6 and a trailing cam portion 7. When roller 5 meets the cam
portion 6, 7, grippers 3 open and release and the printed sheet
floats on stack 1, due to inertia, and gravity. Heavy paper, or
carton stock which was printed requires early opening of the
gripper in order to prevent hard impact of the sheets on the
abutment and limit stops of the stack. If the paper is thin, the
gripper should open later. This differential adjustment of gripper
openings requires adjustment of leading cam track 6. The trailing
cam track 7 is provided in order to hold grippers 3 open for such a
period that the once released sheet will not be caught again by the
grippers and, inadvertently, continued to be transported.
Large differences in weight of paper sheets to be handled require
wide adjustment limits of the gripper opening, during any one
cycle.
The leading cam 6 is formed as a track 6' which forms part of a
parallelogram suspension, that is, which is suspended by a pair of
crank arms, schematically indicated at 8, 9, which are of equal
length. The cranks 8, 9, may be defined as the distance from a
pivot point 12, 12' thereof to the linkage point 14, 14' of arms 8,
9, with the track portion 6'. The crank arm 9, itself, may form
part of a double armed lever 10, and the pivot point of the
trailing arm 8, remote from the track portion 6' is coaxial with
the swing, or center pivot point of the trailing cam portion 7. The
position of track portion 6' is adjustable by means of an
adjustment rod 11, engaging the double arm lever 10. Adjustment rod
11 may be manually adjusted; as shown, however, the position of rod
11 can be controlled automatically in dependence on machine speed
by providing a transducer-converter 31, receiving a machine input,
which controls as its output the position of rod 11, as
schematically indicated by the connecting arrow 30. The
transducer-converter can be entirely mechanical, as schematically
shown a centrifugal controller, or maybe electrical, hydraulical or
otherwise, so long as machine speed is senses and converted into
motion being transmitted to arm 10. Arm 10 itself pivots about
point 12', which causes a shift in height of the leading edge 6
with respect to the conveyor chain, and additionally swinging of
the trailing cam portion 7 about shaft 12 of the sprocket wheel 13.
When the adjustment is automatic, the transfer function relating
speed of the main drive, and the position change of the cam tracks
may be linear, or non-linear, to provide an adjustable transmission
ratio which can take into consideration format, that is size of the
printed sheet, as well as paper quality. Thus, transducer-converter
31 may have linear, or non-linear, or manually adjustable and
variable transfer characteristics. The two final positions of which
the adjustment cams, that is element 6 and element 7 are capable is
illustrated by full line and chain dotted lines, respectively.
The controlling edge of the leading cam 6 is arranged to form a
flat, shallow angle with respect to the center line of the conveyor
chain 2. If so arranged, a maximum adjustment angle of
approximately 40.degree., that is, a shift in position of
40.degree. of the lever 10, and hands of arm 8, provides a large
range of adjustment, as indicated in FIG. 1, without change of the
angle of attack of roller 5 with respect to track 6'.
The transfer of control surface from track 6 to the trailing cam 7
should be smooth. To provide such a smooth transfer, the start of
the trailing cam is arranged to be approximately in the
prolongation of a connecting line interconnecting the pivot point
12 of the trailing curve 7 and the suspension point 14 of the
trailing end of the leading cam 6. The trailing suspension point 14
of the leading cam track 6 can be, itself, connected on or formed
on the trailing cam 7. The controlling cam edge of the trailing cam
7 is eccentric with respect to its axis 12, in such a way that the
radial distance decreases in direction of movement of the control
roller 5. The track 6' is arranged to partly overlap with the cam
surface 7 and, in this region, is formed with a bowed control edge
15 having a lesser radius than the radius of the cam portion 7.
Some play of the drive is difficult to compensate; to overcome
play, a spring 16 is hooked to the end of the trailing cam opposite
the cam surface 7 to interconnect with the shaft point, or pivot
point of the double arm lever 10.
As best seen in FIG. 2, the leading cam 6 both overlaps as well as
surrounds cam 7, as well as the double armed lever 10. This permits
engagement by the full width of roller 5, and particularly during
the greatest acceleration, and thus during occurrence of the
greatest dynamic forces, that is, upon opening of the grippers; the
inter-engaging portions themselves become active only in the region
of substantially lesser forces being transferred to the
rollers.
Both cam curves 6, and 7 can be adjusted during actual operation,
and without stopping the machine; the limit of adjustment is
provided by an elongated opening 17 in the double arm lever 10, in
which a pin 18 fixed in position on the machine is engageable.
The present invention has been illustrated in connection with sheet
transport apparatus for use in combination with a printing machine;
various changes and modifications may be made within the inventive
concept to adapt the invention to various uses.
* * * * *