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United States Patent |
5,119,728
|
Rogge
|
June 9, 1992
|
Doctor device for the self-washing inking unit of a rotary printing press
Abstract
A doctor device for the washing inking unit of a rotary printing press
includes a doctor carrier, on which two doctor blades are attached. The
doctor blades are parallel to and coextensive with each other and are able
to be put into engagement with an inking roller. Together with the inking
roller, the doctor carrier and sealing means provided at the end thereof,
the doctor blades define a sealed ink chamber. The ink is supplied to and
removed from the ink chamber through ducts. The doctor carrier is able to
be brought into engagement with the inking roller by sealing moldings. In
order to ensure that no ink is able to escape from the ink chamber, even
when the doctor device oscillates, the sealing moldings are formed of
elastic or elastomeric material, which, on their sides facing the inking
roller, have dihedral, downwardly sloping surfaces for supporting the end
parts of the doctor blades. Between the dihedral surface, a curved sealing
surface if provided. The curved sealing surface has the shape of a
cylindrical shell and is able to be brought into engagement with the
inking roller. The sealing surface has a radius of curvature corresponding
to the inking roller.
Inventors:
|
Rogge; Dieter (Lengerich, DE)
|
Assignee:
|
Windmoeller & Hoelscher (Lengerich, DE)
|
Appl. No.:
|
643991 |
Filed:
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January 22, 1991 |
Foreign Application Priority Data
Intern'l Class: |
B41F 031/04; B41F 031/06; B41L 027/08 |
Field of Search: |
101/366,363,350,364,148,207,208,209,210
118/259,261
|
References Cited
U.S. Patent Documents
3400658 | Sep., 1968 | Gagliardi et al. | 101/366.
|
4414900 | Nov., 1983 | Kraus et al. | 101/363.
|
4958561 | Sep., 1990 | Grosshauser et al. | 101/363.
|
Primary Examiner: Fisher; J. Reed
Attorney, Agent or Firm: Fleit, Jacobson, Cohn, Price, Holman & Stern
Claims
I claim:
1. A doctor device for a self-washing inking unit of a rotary printing
press, comprising:
a doctor carrier,
an inking roller, a sealing means,
two doctor blades, parallel to each other and able to be brought into
engagement with said inking roller, attached to the doctor carrier, said
doctor blades, together with the inking roller, the doctor carrier and
sealing means provided terminally on each end of the doctor carrier,
defining a closed ink chamber,
ducts for the supply of ink to and removal of ink from the ink chamber, and
loading means for pressing the doctor carrier against the inking roller,
wherein the sealing means are formed of moldings of elastic material and,
at a side facing the inking roller, each having downwardly sloping,
dihedral sealing surfaces for receiving terminal parts of the doctor
blades and between which there is a respective curve for a roller sealing
surface, which is able to engage the inking roller, each said roller
sealing surface having the form of a cylindrical shell with a radius of
curvature corresponding to the radius of the inking roller.
2. A doctor device as claimed in claim 1, characterized in that the curved
sealing surfaces includes a layer of deformable material with a high
resistance to wear.
3. A doctor device as claimed in claim 2, characterized in that the layer
is formed of Teflon.
4. A doctor device as claimed in claim 2, characterized in that the layer
is formed of a mixture of Teflon and copper.
5. A doctor device as claimed in claim 1, characterized in that the molding
is provided with an aperture filled with a member of soft elastic
material.
6. A doctor device as claimed in claim 5, characterized in that the soft
elastic material is cellular rubber.
7. A doctor device as claimed in claim 5, characterized in that the
aperture is limited towards the dihedral and curved sealing surfaces by a
marginal rim of essentially constant thickness.
8. A doctor device as claimed in claim 1, characterized in that the
moldings are retained in recesses of holding members, which, at end
surfaces thereof, are screwed to the doctor carrier.
9. A doctor device as claimed in claim 8, characterized in that the doctor
carrier is provided, at an end surface thereof, with holding bolts, which
are fitted in holes in the moldings.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a doctor device for a self-washing inking unit of
a rotary printing press. The doctor device includes a doctor carrier, on
which two doctor blades are attached. The doctor blades are are parallel
to each other, and are able to brought into engagement with an inking
roller. Together with the inking roller, the doctor carrier, and sealing
means provided terminally on the latter, the doctor blades define a closed
ink chamber. Ducts for the supply of ink to and removal of ink from the
ink chamber are provided, as are loading means for pressing the doctor
carrier against the inking roller.
2. Description of the Related Art
An example of a doctor device of this type is described in German patent
publication 3,135,711 A, and is schematically illustrated in FIGS. 1 and 2
of the drawings. This doctor device consists of a doctor carrier 1, which,
on its side facing the engraved roller 5, has a trough-like recess. The
doctor carrier 1 is provided with downwardly sloping, dihedral support
surfaces, placed symmetrically relative to its longitudinal median plane
II--II. The support surfaces support the doctor blades 7 and 8, which are
screwed to the doctor carrier in a known manner using clamping members 30.
The ends of the doctor carrier 2 are provided with terminal sheet metal
members 3 and 4 in order to produce sealed joints between the doctor
carrier and the end faces of the doctor roller 5. Between the terminal
sheet metal members 3 and 4 and the end faces of the doctor roller 5,
small lateral gaps remain, which make it possible for a reciprocating
motion of the doctor device to take place parallel to the longitudinal
axis of the doctor roller 5. Besides being sealed off by the two lateral
terminal sheet metal members 3 and 4, the ink chamber 2 is sealed off by
doctor blades 7 and 8, which are in engagement with the doctor roller 5.
It is possible for ink to emerge through the lateral gaps 6. Such ink is
then caught by an ink sump 9, provided underneath the doctor roller 5.
The doctor carrier 1 may be pressed against the engraved roller 5 and moved
clear of the same by an engaging device which is not illustrated. The ink
necessary for printing is pumped through an ink feed hole 10 provided in
the doctor carrier 1, and into the ink chamber 2, the excess quantity of
ink being returned through the ink return hole 11 into the ink container.
This known doctor device operates satisfactorily as such. However, there
is a disadvantage, in that it is possible for ink to emerge from the ink
chamber through the lateral gaps 6. This ink then has to be caught in an
open ink sump 9, and the doctor device will be soiled by the emerging ink.
Also, solvent may evaporate from the ink, which then contaminates the
atmosphere. Furthermore such evaporation of the solvent means that more
solvent is used.
SUMMARY OF THE INVENTION
Accordingly, one object of the invention is to provide a doctor device of
the type initially mentioned, which is provided with an ink chamber
incorporating sealing means engaging the inking roller, and from which it
is not possible for ink to escape, even when the doctor device is
oscillated in relation to the inking roller.
In order to achieve this in a doctor device of the type initially
mentioned, the sealing means includes moldings of elastic or elastomeric
material, which, at sides thereof facing the inking roller, have
downwardly sloping, dihedral sealing surfaces for mounting the terminal
parts of the doctor blades. Between the moldings, there is a respective
sealing surface, which is able to be put in engagement with the inking
roller and has the form of a cylindrical shell with a radius of curvature
corresponding to the radius of the inking roller. The moldings constructed
in accordance with the invention ensure a satisfactory sealing action of
the ink chamber, since they contact both the doctor blades and also the
circumferential surface parts of the inking roller. The moldings are, in
the present case, pressed sufficiently firmly against the inking roller so
that there is no gap between the moldings and the inking roller, and the
doctor blades, through which the ink might be able to leak.
It is, preferably, the case that the sealing surface is both curved in the
form of a segment of a cylindrical shell and is formed of elastic and/or
plastic material with a good resistance to wear. In this case, it is
particularly advantageous if the layer forming the sealing surface is
formed of a tetrafluorethylene polymer, such as Teflon. Furthermore, the
layer may be formed of a mixture of Teflon and copper or, alternatively,
copper powder, so that good thermal conduction is ensured.
In a preferred embodiment of the invention, the molding is provided with a
recess or an aperture which is filled with soft elastic material. In
accordance with a further, particularly useful feature, this soft elastic
material is cellular rubber. Cellular rubber has a satisfactory elasticity
and owing to its cellular structure, is not able to absorb and thus become
clogged with ink.
As part of a further convenient form of the invention, the recess or
aperture of each molding is bounded or limited towards the sealing
surfaces by a marginal rim of substantially constant thickness. Thus,
there is a generally equal resilient pressing action of the sealing
surface.
The moldings may be held in place in recesses in holding members, which, at
their end surfaces, are attached by screws to the doctor carrier. The
doctor carrier may be provided with retaining bolts at their ends so that
the moldings do not have to be squeezed to be held and so that they
maintain their full elasticity with respect to their sealing surfaces.
BRIEF DESCRIPTION OF THE DRAWINGS
One working embodiment of the invention will now be described, with
particular reference being made to FIGS. 3 through 5 of the drawings.
FIG. 1 is, as noted above, a schematic illustration of a known doctor
device.
FIG. 2 is a part sectional, side view of FIG. 1.
FIG. 3 is an end view, corresponding to FIG. 1, of a doctor device set in
engagement with an engraved roller.
FIG. 4 is a horizontal, part sectional view similar to FIG. 2, taken
through the doctor device along line IV--IV of FIG. 3.
FIG. 5 is a perspective view of a molding providing for sealing action at
the end of the ink chamber.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The doctor device illustrated in FIGS. 3 through 5 has a basic structure
which corresponds to that of the doctor device illustrated in FIGS. 1 and
2. The essential difference between the device shown in FIGS. 3 through 5
and that shown in FIGS. 1 and 2 is in the presence of moldings 19, which
completely seal off the ink chamber, in place of the conventionally used
terminal sheet metal elements. The doctor carrier 12 is provided with an
ink chamber 13, formed by a trough-like recess in the carrier. The ink
chamber is supplied with ink through a hole 14 in carrier 12. Excess ink
is drained off through a hole 15. A first holder 16 and a second holder 17
are attached by screws (not indicated) to opposite end surfaces of the
doctor carrier 1. By means of such holders, elastic sealing elements 18
are held in place between the end surfaces of the doctor carrier 12 and
the clamping members 16 and 17. As shown in FIG. 5, each sealing element
18 includes a rubber molding 19, which has two obliquely running surfaces
20 and 21. The two doctor blades 22 and 23 have their free end portions
resting on these two surfaces 20 and 21. Adjoining the two oblique
surfaces 20 and 21 there is an arcuate surface 25, which corresponds to
the radius of the engraved roller 24. The surface 25 is preferably coated
with a mixture of copper and Teflon. This layer is indicated by reference
number 26. The surface 25 provides sealing engagement with the engraved
roller 24, so that the ink chamber 13 is sealed off completely in relation
to the engraved roller 24 by the blades 22 and 23 and, at the ends
thereof, by the two rubber moldings 19.
It is also to be noted that on the one hand, owing to the use of Teflon,
there is only a very small amount of friction and, on the other hand, the
copper embedded in the Teflon leads to a satisfactory distribution of
heat. It will furthermore be seen from FIG. 5 that a soft cellular rubber
inlay 27 is placed in the rubber molding 19 in such a manner that between
the cellular rubber inlay 27 and the engraved roller 24, there is only a
thin strip of the rubber molding material. Since the cellular rubber 27 is
softer than the rubber molding, feed movement of the ink chamber doctor
may readily take place as necessary when there is wear of the doctor
blades, since the cellular rubber is very readily compressed. Owing to the
particular design of the rubber molding, that is to say, owing to the
small thickness of the layer of the rubber material molding in between the
cellular rubber and the engraved roller 24, there is an even distribution
of pressure during feed movement for adjustment, so that there is always a
satisfactory sealing effect between the ink chamber 13 and the terminal or
end parts of the ink chamber doctor.
As shown in FIG. 4, the distance between the rubber moldings 19 is less
than the length of the engraved roller 24. It is, in this manner, assured
that even in the case of oscillating movement of the ink chamber doctor
12, no lateral escape of ink is possible.
The rubber moldings 19 each have a slot 28. A bolt 29, one of which is set
in the ink chamber doctor 1 at each end, extends into each slot 28. It is,
in this manner, assured that the rubber moldings are loosely held between
the ink chamber doctor 12 and the members 16 and 17 without being
squeezed.
In a conventional manner, the doctor blades are screwed by knife holders 30
to the ink chamber doctor 12, as in the known device shown in FIGS. 1 and
2.
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