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Description  |
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FIELD OF THE INVENTION
The present invention is directed generally to a method and apparatus for
preparing a printing plate. More specifically, the present invention is
directed to a method and apparatus for preparing one or more printing
plates adjacent a plate handling device. Most particularly, the present
invention is directed to a method and apparatus for preparing a printing
plate by use of a printing plate preparation device so that the prepared
plate or plates can be mounted on a printing cylinder of a rotary printing
press. The printing plate or plates are placed into a printing plate
preparation device either manually or by utilization of a printing plate
feeding device in the form of a three axis robot. The printing plate
preparation device is movable between a plate preparation position and a
printing plate mounting or standby position. Plates can be removed from
the preparation device in the mounting position and secured to a printing
plate cylinder.
DESCRIPTION OF THE PRIOR ART
In the field of rotary printing, it is frequently necessary to change
printing plates in an expeditious manner. It is beneficial to avoid having
the printing press stand idle for a long period of time. Thus it is
desirable to be able to prepare the next printing plate which will be
mounted on the plate cylinder and to have this prepared printing plate
situated adjacent the plate cylinder so that it can be quickly and easily
attached to the plate cylinder.
One prior art method and apparatus for mounting printing plates is shown in
German Patent Publication DE 42 19 822 A1. In this prior art publication
there is disclosed a preparation device on which a printing plate to be
mounted on the printing cylinder is prepared. The preparation device is
within the range of movement of a robot. This preparation device includes
a stationary frame with a hook rail. The printing plate is suspended in
this stationary frame and is transported by the robot from the preparation
device to the vicinity of the printing plate cylinder where it is then
mounted on the plate cylinder.
One significant limitation of this prior art device is that it requires a
substantial amount of space. When two printing plate cylinders are located
near to each other, the space becomes very restricted if this prior art
plate mounting device is used. When the space between the printing plate
cylinders becomes compromised by these prior art preparation devices,
access to the plate cylinders becomes very restricted and is thus made
much more difficult. The accessibility to the printing plates is also made
that much more difficult by the inclusion of a device for use in
supporting one end of the printing plate to be mounted on the plate
cylinder.
A particular limitation of the prior art plate mounting device discussed in
the German Patent Publication DE 42 19 822 A1 is that the robot device
must perform complicated movements in several axes. For example, this
robot device must execute various pivot movements for transporting the
printing plate. The robot device is thus quite complicated and is
expensive to construct.
Japanese Patent Publication JP 1-176558 and U.S. Pat. No. 4,727,807 both
disclose devices in which the printing plate is prepositioned while being
suspended. The printing plate is subsequently mounted on a plate cylinder
by use of a multi-axial manipulating device.
It will be seen that a need exists for a printing plate preparing device
that overcomes the limitations of the prior art devices. The printing
plate preparing device and its method of use in accordance with the
present invention, provides such a device and is a significant improvement
over these prior art devices.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a method and an
apparatus for preparing a printing plate.
Another object of the present invention is to provide a method and
apparatus for preparing a printing plate for mounting on a plate cylinder
of a rotary printing press.
A further object of the present invention is to provide a method and
apparatus for preparing a plate cylinder for mounting and having a
manipulating device for transporting the plate which travels over only a
short distance between a plate preparation position and a plate mounting
or standby position.
Yet another object of the present invention is to provide a method and
apparatus for preparing a printing plate which makes possible the simple
preparation of the printing plate without restricting the access to the
printing units.
As will be discussed in detail in the description of the preferred
embodiment which is presented subsequently, the method and apparatus for
preparing a printing plate for mounting on a plate cylinder of a rotary
printing press in accordance with the present invention uses a plate
handling device to remove a prepared printing plate from a printing plate
preparation device. The plate preparation device has at least one
suspension strip which receives the leading end of a printing plate. The
preparation device is shiftable between a plate preparation position
remote from the printing cylinder, in which the printing plate or plates
are suspended in a generally vertical position, and a printing plate
mounting position or standby position in which the plates are generally
horizontal. In this standby position of the plate preparation device, the
leading edges of the plate or plates in the preparation device are
situated so that they can be easily grasped by the plate manipulating
device and moved into position for mounting on the plate cylinder.
In the present invention, the existing inking system protector or shield is
modified slightly and is used as a portion of the plate preparation
device. Thus the device for preparing printing plates in accordance with
the present invention utilizes little or no additional space adjacent the
printing cylinders. Since virtually no additional space is used, the
device for preparing plates in accordance with the present invention does
not require modification of the press structure and does not compromise
access to the printing plate.
Because the present invention utilizes an intermediate printing plate
storage device for the printing plates in the vicinity of the plate
cylinder, the exchange of printing plates on the plate cylinder can be
accomplished very rapidly. The printing plate manipulating device needs to
travel only a very short distance for transporting and for mounting the
printing plates. This significantly reduces the set-up time required for
the printing presses. Such a reduction in set-up time is clearly
beneficial from a production standpoint.
The manipulating device that is used to move the prepared printing plates
from the plate preparation device to the printing plate cylinder is
required to move on only one level generally in a simple, reciprocating
manner. This means that no complicated pivot mechanisms are required. Thus
the device is quite simple and inexpensive.
The printing plate that will be placed on the plate cylinder is initially
prepared at a point remote from the press and is then positioned in the
printing plate preparation device while the device is in its preparation
position away from the plate cylinder. This allows for easy access for
manual operation as well as ease of access to the automatic transport
systems in a danger free manner.
The method and apparatus for preparing a printing plate in accordance with
the present invention overcomes the limitations of the prior art. It is a
substantial advance in the art.
BRIEF DESCRIPTION OF THE DRAWINGS
While the novel features of the method and apparatus for preparing a
printing plate in accordance with the present invention are set forth with
particularity in the appended claims, a full and complete understanding of
the invention may be had by referring to the detailed description of the
preferred embodiment which is presented subsequently, and as illustrated
in the accompanying drawings, in which:
FIG. 1 is a schematic side elevation view of the device for preparing a
printing plate in accordance with the present invention and showing the
device in the plate mounting or standby position "W"; and
FIG. 2 is a schematic side elevation view of the device in accordance with
the present invention and showing the device in the printing plate
preparation position "B".
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring initially primarily to FIG. 1, a plate cylinder 1 of a rotary
printing press is supported between spaced lateral press side frames 3 and
4, and is rotatable around its cylinder axis 2. This plate cylinder 1 is
provided with printing plate end fastening elements 6, 7, 8 and 9 for
receiving the leading ends of printing plates, such as plates 11 and 40.
In the instant example, four such fastening elements 6, 7, 8 and 9 are
disposed in the plate cylinder 1, with each fastening element extending in
the axial direction of cylinder 1 and parallel with the cylinder axis 2.
The length of each of the fastening elements 6, 7, 8 and 9 is
approximately one-half of the cylinder length. These fastening elements 6,
7, 8 and 9 are thus divided over the printing plate width so that two
printing plates 11 or 40 are secured in each fastening element 6, 7, 8 and
9 and can each be independently actuated within this division as well as
in respect to each other. The fastening elements 6, 7, 8 and 9 are offset
from each other in the circumferential direction of the plate cylinder 1
by approximately 90.degree.. A fastening element 8, 9 is respectively
disposed opposite each fastening device 6, 7. It will be understood that
the printing cylinder 1 is generally conventional in structure and
operation, as is the rotary printing press in which it is supported. The
press itself forms no part of the present invention and is thus not
discussed in detail.
A printing plate manipulating device, generally at 12, is disposed between
the lateral frames 3 and 4 and is usable for mounting, removing and
transporting printing plates 11 or 40. The plate manipulating device 12
essentially consists of two spaced linear drives 13 and 14 that are fixed
in place on the frames 3 and 4, a cross arm 16 extending axially between
the drives 13 and 14 and parallel with the cylinder axis 2, and a number
of plate gripper devices 17, for example four gripper devices 17. The
gripper devices 17 are fastened on the cross arm 16, which is moved by the
synchronized rotation of the linear drives 13, 14. In this way, the
gripper devices 17 are moved on a transport level 18 which extends
parallel with the linear drives 13 and 14 as well as with a tangential
line defined by the plate cylinder 1 and the prepositioned printing plate
11. As may be seen most clearly in FIG. 1, each of the linear drives 13 or
14 is a lead screw that is turned by a schematically depicted reversible
motor M. The cross arm 16 is carried by the linear drives 13 and 14 and is
moved either to the left or to the right, as shown in FIG. 1, by rotation
of the linear drives 13 and 14 in a synchronous manner.
The printing plates 11 and 40 used are each provided with front and rear
suspension edges 19 and 21, which cooperate with the fastening elements 6,
7, 8 and 9 of the plate cylinder 1. The suspension edges 19 and 21 are
structured to be dimensionally stable and each have legs 22 and 23 with an
opening angle .alpha., for example of 45.degree.. A height h21 of the
suspension edges 19, 21 is a function of this opening angle .alpha. and of
the length of the legs 22, 23. As may be seen in FIG. 1, the legs 22 and
23 of each suspension edge 19 or 21 cooperates to form a receptacle or
pocket at the front and rear portions of each of the printing plates 11 or
40. These front and rear suspension edges 19 and 21 thus are engageable
with the printing plate fastening elements 6, 7, 8 and 9 to secure the
front and rear ends of a printing plate 11 or 40 to the surface of the
plate cylinder 1.
As may be seen most clearly in FIG. 2, an inking system protector 24 is
associated with the plate cylinder 1. This inking system protector 24
serves a dual function in the present invention. It performs its usual and
conventional function of protecting an inking system, that is not depicted
in the drawings, from damage and from debris. In accordance with the
present invention, this inking system protector 24 also functions as a
printing plate storage device 24. The printing plate ink protector and
plate storage device 24 is supported at its first end adjacent the plate
cylinder 1 for upward pivotal movement by means of shaft journals 26 which
extend between the lateral side frames 3 and 4. The inking system
protector and plate storage device 24 consists of a plate removal chute
27, and of a printing plate preparation device 28. The two separate
components 27 and 28 may be seen more clearly in FIG. 2.
The printing plate removal chute 27 which is used to receive used printing
plates 11 from cylinder 1, has an upper wall 29 and a lower, opposite,
wall 29. The removal chute 27 is positioned so that its upper end near the
cylinder 1 is approximately parallel with the transport level 18 of the
printing plate 11 or 40. This upper straight end of removal chute 27 near
the cylinder 1 is followed by a section in the shape of a quarter circle
which, in turn, terminates in a lower straight part. The printing plate
preparation device 28 is pivotably seated with respect to the cylinder
axis 2, on the printing plate storage assembly 24. The printing plate
preparation device 28 has two spaced pivot arms 32, which are pivotably
connected by means of shaft journals 33, to both sides of the plate
removal chute 27 which is part of the printing plate storage device 24. On
their free ends near the cylinder 1, these two spaced pivot arms 32 are
connected by a first suspension strip 34. This suspension strip 34 extends
axially parallel with the cylinder axis 2 and has a nose-shaped or
somewhat wedge shaped cross section. The cross section of the suspension
strip 34 is adapted, in the direction of the plate cylinder 1, to the
shape of the front suspension edge 19 of the printing plate 11 or 40. In
the preferred embodiment, a first support surface 36 of the suspension
strip 34 is generally parallel with the transport level 18. A second
suspension surface 37, adjoining the first suspension surface 36 in the
direction of the plate cylinder 1, forms an opening angle .beta. of, for
example 45.degree., with the first support surface 36. An end of the
suspension strip 34 that is facing away from the plate cylinder 1 is
provided with a chamfer 38 which is structured such that a height h38 of
the chamfer 38, with respect to the support surface 36, is greater than a
height h21 of the rear suspension edge 21 of the printing plate 11. In
this way, the chamfer 38 is used as a guide surface for the suspension
strip 34 for the rear suspension edge 21 of the printing plate 11. In
addition to the first suspension strip 34, it is possible, as shown in the
preferred embodiment, to fasten a second suspension strip 39 between the
pivot arms 32 and remote from the cylinder 1. Alternatively, this second
suspension strip 39 can also have its own pivot arms 32 and can therefore
be pivotably seated independently of the first suspension strip 34. This
second suspension strip 39 is used to receive, and to support, the leading
end of a second, fresh printing plate 40.
The first and second suspension strips 34, 39 are each provided with stops,
not shown, for the axial positioning of the printing plates 11, 40. The
printing plate preparation device 28 can be moved by means of drives, not
shown, from a standby or plate mounting position "W" near the cylinder,
which is used for mounting the printing plates 11 or 40 on the plate
cylinder 1 as shown in FIG. 1, into a preparation position "B" remote from
the cylinder, which is used for placing the printing plates 11 or 40 on
the suspension strips 34 or 39. This preparation position "B" is shown in
FIG. 2. In the standby position "W", the first or upper support surface 36
of the first suspension strip 34 lies approximately parallel with the
transport level 18. In other words, the suspension strip 34 and thus the
printing plate 11 are located approximately horizontally, as shown in FIG.
1. By pivoting the printing plate preparation device 28 through
approximately 90.degree., the printing plate preparation position "B" is
reached. In this position, the support surface 36 of the suspension strip
34 and thus the printing plates 11 and 40 are located approximately
vertically. If two suspension strips 34 and 39 are provided, they are
offset in the preparation position "B", viewed in the vertical direction,
in such a way that a space of the width "b" exists between the suspended
first printing plate 11 and the second suspension strip 39 for the
suspended second printing plate 40.
The suspension of the printing plates 11 and 40 can be performed manually
or, as depicted in FIG. 2 of the preferred embodiment, by utilization of a
plate feed device 41. This plate feed device 41 can consist of a
three-axis plate feed robot 41, whose first axis lies in the direction of
the cylinder axis 2, whose second axis in the vertical direction and whose
third axis in the horizontal direction. This plate feed robot 41 is
provided with a suction gripper 42 for receiving the printing plates 11
and 40. The plate feed robot 41 moves a printing plate 11 or 40, fastened
on the suction gripper 42, into an axial position which is predetermined
with respect to the plate cylinder 1. After having achieved the axial
position, the printing plate 11 or 40 is placed into a horizontal position
corresponding to the position of the suspension strip 34, for example, by
use of a pneumatic cylinder 43. Subsequently a suitable vertical position
of the plate 11 or 40 is achieved, for example, by means of a second
pneumatic cylinder 44. In this way, the fresh, first printing plate 11 is
vertically and axially prepositioned and suspended by its front suspension
edge 19 in the suspension strip 34 by the operation of the three axis
plate feed robot 41. This positioning process can be repeated several
times so that several printing plates 11 or 40 can be located in properly
axial spaced positions on the first and second suspension strips 34 and 39
of the printing plate preparation device 28. It will be understood that
when there is provided a second suspension strip 39 that the plate
suspension process is still performed by the robot 41 but with the
vertical position of the suction gripper 42 of the robot 41 being matched
to the location of the second suspension strip 39.
After the desired number of printing plates 11 or 40 has been suspended in
the first suspension strip 34, or the second suspension strip 39, the
printing plate preparation device 28 with its suspension strips 34 and 39
pivots over 90.degree. from its preparation position "B" into its standby
position "W", so that the suspended printing plates 11, 40 lie
approximately parallel with the transport level 18, and thus are
approximately horizontal in the preferred embodiment, as depicted in FIG.
1. The manipulating device 12 can now grasp the printing plates 11 or 40,
which have been prepositioned in this manner, transport them to a
fastening device 6, 7, 8 or 9 of the plate cylinder 1 and suspend them in
this fastening device 6, 7, 8 or 9.
The movement for shifting the suspension strips 34 and 35 from their
horizontal standby or plate mounting position "W" near the cylinder to
their vertical preparation position "B" remote from the cylinder can also
take place, instead of by the previously described pivot movement, by
means of a guide path, hinged coupling or a combined linear and pivot
movement. In the preferred embodiment, one suspension strip 34 or 39 is
provided for all, for example all four printing plates 11 or 40 to be
placed in the axial direction. In other words, all adjoining printing
plates 11 and 40 to be exchanged on a plate cylinder 1 having two printing
plates 11 and 40 in the circumferential direction are moved together from
the preparation position "B" into the standby position "W" when two
suspension strips 34 and 39 are provided. If only one suspension strip 34
is provided, it is possible, for example, to repeat the pivot process. It
is also possible to assign each axial cylinder section associated with a
printing plate 11 or 40 with its own, independently pivotable printing
plate preparation device 28.
While a preferred embodiment of a method and apparatus for preparing a
printing plate in accordance with the present invention has been set forth
fully and completely hereinabove, it will be apparent that a number of
changes, for example in the overall size of the plate cylinder, in the
drive assembly for the plate cylinder, in the drive motors for the
printing plate manipulating device and the like can be made without
departing from the true spirit and scope of the present invention which is
accordingly to be limited only by the following claims.
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