This application is the U.S. national phase of International Application No. PCT/IB2013/053251, filed 24 Apr. 2013, which designated the U.S. and claims priority to EP Application No. 12165388.5, filed 24 Apr. 2012, the entire contents of each of which are hereby incorporated by reference.
The present invention generally relates to an intaglio printing press of the type comprising an intaglio cylinder and an ink wiping system with a rotating wiping roller assembly contacting a circumference of the intaglio cylinder for wiping excess ink from the surface of the intaglio cylinder, a rotational speed of the wiping cylinder being adjustable with respect to a rotational speed of the intaglio cylinder.
European Patent Publication No. EP 0 633 134 A1 discloses an intaglio printing press comprising a wiping cylinder whose rotational speed is controlled and adjusted with respect to a rotational speed of a plate cylinder by way of corresponding independent motors.
A problem with the above solution resides in the fact that, in case of failure of an independent drive, the associated system and function become inoperative and cannot be exploited further unless the defective drive is replaced by a new drive, which process is typically time-consuming and involves substantial downtimes which negatively affect productivity.
An improved and more robust approach is therefore required.
A general aim of the invention is therefore to provide an intaglio printing press of the above-mentioned-type comprising means to adjust a rotational speed of the wiping roller assembly, which solution is more robust than the solutions known in the art.
A further aim of the invention is to provide such a solution which is as compact as possible in order to facilitate the integration thereof in the intaglio printing press.
Still another aim of the invention is to provide such a solution which can be efficiently used to adjust a rotational speed of a wiping cylinder with respect to an intaglio cylinder of an intaglio printing press.
These aims are achieved thanks to the adjustable drive unit defined in the claims.
There is accordingly provided an intaglio printing press comprising an intaglio cylinder and an ink wiping system with a rotating wiping roller assembly contacting a circumference of the intaglio cylinder for wiping excess ink from the surface of the intaglio cylinder, a rotational speed of the wiping cylinder being adjustable with respect to a rotational speed of the intaglio cylinder, wherein the intaglio printing press comprises an adjustable drive unit, which adjustable drive unit is interposed between the wiping roller assembly acting as a rotating output body of the adjustable drive unit and a driving gear coupled to the intaglio cylinder and acting as a rotating input body of the adjustable drive unit. The adjustable drive unit is designed to allow selected adjustment of a rotational speed of the wiping roller assembly with respect to a rotational speed of the driving gear. In an adjusting state of the adjustable drive unit, driving into rotation of the wiping roller assembly is adjusted by means of an adjustment motor of the adjustable drive unit to change the rotational speed of the wiping roller assembly with respect to the rotational speed of the intaglio cylinder. In a non-adjusting state of the adjustable drive unit, the adjustment motor is inoperative and driving into rotation of the wiping roller assembly is performed exclusively mechanically via the adjustable drive unit, the wiping roller assembly rotating at a defined rotational speed with respect to the rotational speed of the intaglio cylinder.
In accordance with the invention, it shall therefore be appreciated that the adjustment motor is only operative in the adjusting state of the adjustable drive unit, i.e. the adjustment motor is only used for the purpose of adjusting a rotational speed of the wiping roller assembly with respect to the rotational speed of the intaglio cylinder. In the non-adjusting state, the adjustment motor is totally inoperative and the wiping roller assembly is driven into rotation exclusively mechanically via the adjustable drive unit. In other words, any failure of the adjustment motor will not have any impact on the normal operation of the intaglio printing press. In addition, since the adjustment motor is only operative in the adjusting state of the adjustable drive unit, usage of the adjustment motor is reduced, leading to an extended usability.
In accordance with a preferred embodiment of the invention, the adjustable drive unit comprises an adjustable mechanical transmission unit having a drive input coupled to and rotating together with the driving gear, a drive output coupled to and rotating together with the wiping roller assembly, and a control input coupled to and driven into rotation by the adjustment motor.
In accordance with a preferred embodiment of the invention, the adjustable mechanical transmission unit is designed as a planetary gear unit comprising a ring gear acting as the drive input of the planetary gear unit, a star gear disposed centrally with respect to the ring gear and acting as the control input of the planetary gear unit, and a plurality of planet gears interposed between and meshing with the ring gear and the star gear, which plurality of planet gears are carried by a planet carrier coaxial with the ring gear and star gear and acting as the drive output of the planetary gear unit.
Advantageously, the rotational speed of the wiping roller assembly is adjustable, in the adjusting state of the adjustable drive unit, within a range of +20% and −20% with respect to a nominal rotational speed of the wiping roller assembly in the non-adjusting state of the adjustable drive unit.
In a preferred variant, the intaglio printing press further comprises a retractable coupling mechanism coupled between a drive output of the adjustable drive unit and a driving head part of the wiping roller assembly, which retractable coupling mechanism is operable to release the driving head part of the wiping roller assembly during a maintenance operation.
In a further variant, the wiping roller assembly is coupled to an output of the adjustable drive unit via a spherical bearing.
Also claimed is an adjustment system designed to allow adjustment of the rotational speed of a wiping roller assembly of the aforementioned intaglio printing press.
Further advantageous embodiments of the adjustable drive unit and of the printing press form the subject-matter of the dependent claims and are discussed below.
Other features and advantages of the present invention will appear more clearly from reading the following detailed description of embodiments of the invention which are presented solely by way of non-restrictive examples and illustrated by the attached drawings in which:
The present invention will be described in the particular context of the application to an intaglio printing press as used for the production of banknotes and like security documents.
Within the context of the present invention, the expression “intaglio cylinder”, when used, designates either a cylinder whose surface is provided with intaglio patterns engraved directly onto the circumference of the cylinder or of a cylinder sleeve, or a plate cylinder carrying on its circumference at least one intaglio printing plate with engraved intaglio patterns (the second solution being now more common in the art). In the following description, it will be assumed for the sake of illustration that the intaglio cylinder is a plate cylinder carrying several intaglio printing plates on its circumference. In this context, the expression “chablon cylinder” (which is equivalent to the expression “colour-selector cylinder” also used in the art) is to be understood as designating a cylinder with raised portions whose purpose is to selectively transfer ink patterns to the circumference of the plate cylinder, whether indirectly (as shown in
More precisely,
The sheets are fed from the sheet feeder 2 onto a feeder table and then onto the impression cylinder 7. The sheets are then carried by the impression cylinder 7 to the printing nip between the impression cylinder 7 and the plate cylinder 8 where intaglio printing is performed. Once printed, the sheets are transferred away from the impression cylinder 7 for conveyance by a sheet transporting system 15 in order to be delivered to the delivery unit 4. The sheet transporting system 15 conventionally comprises a sheet conveyor system with a pair of endless chains driving a plurality of spaced-apart gripper bars for holding a leading edge of the sheets (the freshly-printed side of the sheets being oriented downwards on their way to the delivery unit 4), sheets being transferred in succession to a corresponding one of the gripper bars.
During their transport to the sheet delivery unit 4, the freshly printed sheets are preferably inspected by an optical inspection system 5. In the illustrated example, the optical inspection system 5 is advantageously an inspection system as disclosed in International Publication No. WO 2011/161656 A1 (which publication is incorporated herein by reference in its entirety), which inspection system 5 comprises a transfer mechanism and an inspection drum located at the transfer section between the impression cylinder 7 and chain wheels of the sheet transporting system 15. The optical inspection system 5 could alternatively be an inspection system placed along the path of the sheet transporting system 15 as described in International Publications Nos. WO 97/36813 A1, WO 97/37329 A1, and WO 03/070465 A1. Such inspection systems are in particular marketed by the Applicant under the product designation NotaSave®.
Before delivery, the printed sheets are preferably transported in front of a drying or curing unit 6 disposed after the inspection system 5 along the transport path of the sheet transporting system 15. Drying or curing could possibly be performed prior to the optical inspection of the sheets.
The inking system comprises in this example five inking devices 20, all of which cooperate with the ink-collecting cylinder 9 that contacts the plate cylinder 8. It will be understood that the illustrated inking system is adapted for indirect inking of the plate cylinder 8, i.e. inking of the intaglio printing plates via the ink-collecting cylinder 9. The inking devices 20 each include an ink duct 21 cooperating in this example with a pair of ink-application rollers 22. Each pair of ink-application rollers 22 in turn inks a corresponding chablon cylinder 23 which is in contact with the ink-collecting cylinder 9. As is usual in the art, the surface of the chablon cylinders 23 is structured so as to exhibit raised portions corresponding to the areas of the intaglio printing plates intended to receive the inks in the corresponding colours supplied by the respective inking devices 20.
As shown in
The twin-carriage configuration of the intaglio printing press 1 illustrated in
The ink wiping system 10, on the other hand, typically comprises a wiping tank, a wiping roller assembly 11 supported on and partly located in the wiping tank and contacting the plate cylinder 8, cleaning means for removing wiped ink residues from the surface of the wiping roller assembly 11 using a wiping solution that is sprayed or otherwise applied onto the surface of the wiping roller assembly 11, and a drying blade contacting the surface of the wiping roller assembly 11 for removing wiping solution residues from the surface of the wiping roller assembly 11. A particularly suitable solution for the ink wiping system 10 is disclosed in International Publication No. WO 2007/116353 A1 which is incorporated herein by reference in its entirety.
In contrast to the first embodiment shown in
The inking devices, designated by reference numerals 20*, each include, in this example, an ink duct 21*, an ink-transfer roller 24*, and a pair of ink-application rollers 22* adapted to cooperate with the associated chablon cylinder 23*. The inking devices 20* are supported on an inking carriage 56 that is adapted to move between a working position (shown in
Both the intaglio printing press 1 of
According to the invention which will be described in reference to a preferred embodiment thereof which is illustrated by
In accordance with the invention, the adjustable drive unit is designed to allow selected adjustment of a rotational speed of the wiping roller assembly 11 with respect to a rotational speed of the intaglio cylinder 8. More precisely, in accordance with the invention, in an adjusting state of the adjustable drive unit, driving into rotation of the wiping roller assembly 11 is adjusted by means of an adjustment motor of the adjustable drive unit. In a non-adjusting state of the adjustable drive unit, the adjustment motor is inoperative and the driving into rotation of the wiping roller assembly 11 is performed exclusively mechanically via the adjustable drive unit, the wiping roller assembly 11 rotating at a defined rotational speed with respect to the rotational speed of the intaglio cylinder 8.
More specifically, referring to the preferred embodiment of
In accordance with this preferred embodiment, the adjustable mechanical transmission unit is advantageously designed as a planetary gear unit 505 having a drive input coupled to and rotating together with the driving gear 100, a drive output coupled to and rotating together with the wiping roller assembly 11, and a control input coupled to and driven into rotation (when in an adjusting state) by the adjustment motor 700.
In a non-adjusting state of the adjustable drive unit 25, the adjustment motor 700 is inoperative and driving into rotation of the wiping roller assembly 11 is performed exclusively mechanically via the adjustable drive unit 25 (i.e. via the planetary gear unit 505), the wiping roller assembly 11 rotating at a nominal rotational speed defined by the rotational speed of the driving gear 100.
On a drive output side, the planetary gear unit 505 is coupled to a driving head part 11a of the wiping roller assembly 11 via an output member 610. Preferably, such coupling is performed, as illustrated, via a retractable coupling mechanism 800 coupled between a drive output (i.e. output member 610) of the adjustable drive unit 25 and the driving head part 11a of the wiping roller assembly 11, which retractable coupling mechanism 800 is operable to release the driving head part 11a of the wiping roller assembly 11 during a maintenance operation as this will be explained in reference to
In the illustrated example, the adjustment motor 700 is coupled to the control input of the planetary gear unit 505 via a worm drive 720, thereby allowing the adjustment motor 700 to be supported at a right angle with respect to the axis of rotation of the planetary gear unit 505.
The coupling section between the driving head part 11a of the wiping roller assembly 11 and the slideable output member 820 is as such known in the art (see for instance European Patent Publication No. EP 0 881 072 A1). A particularity resides in the fact that the slideable output member 820 can be retracted away from the driving head part 11a (as schematically indicated by the arrow in
Visible in
Also shown is the adjustment motor 700 which drives a control shaft 730 penetrating into a central portion of the planetary gear unit 505, which control shaft 730 is coupled to the output of the adjustment motor 700 via a worm drive 720. The extremity of the control shaft 730, inside the planetary gear unit 505 is designed to act as a star gear SG (with external teeth) and control input of the planetary gear unit 505.
Interposed between the ring gear RG and the star gear SG are a plurality of planet gears PG. Three such planet gears PG are provided, which are distributed at intervals of 120° about the star gear SG. The planet gears PG engage on the one hand with the external teeth of the star gear SG and on the other hand with the internal teeth of the ring gear RG.
The planet gears PG are supported onto a planet carrier PC which is mounted so as to rotate about the same axis of rotation as the ring gear RG and star gear SG. The planet carrier PC here acts as the drive output of the planetary gear unit 505. The planet carrier PC consists in this example of an intermediate member 600 that is supported onto a pair of ball bearings inside the outer casing 510. A central member 605 is further secured to a central portion of the intermediate member 600 to act as one part of the spherical bearing 615 that has already been described above. Rotation of the planet carrier PC is transmitted to the output member 610 via a suitable interconnection between the output member 610 and central member 605, while allowing for some angle (if any) between the axis of rotation of the output member 610 and the axis of rotation of the planet carrier PC.
It will be appreciated that the planet gears PG and the planet carrier PC are conveniently located within a housing formed by the outer casing 510 and the lateral member 515, thereby suitably protecting these elements from exposure to the environment.
In the non-adjusting state (i.e. when the adjustment motor 700 in inoperative), the planetary gear unit 505 merely acts as a reducer stage, the wiping roller assembly 11 being driven into rotation exclusively mechanically via the above-described arrangement so as to rotate at a nominal rotational speed dictated by the driving gear 100. In the adjusting state (i.e. when the adjustment motor 700 is operative), the planetary gear unit 505 acts as a differential stage with the wiping roller assembly 11 being driven into rotation at a rotational speed which is a differential function of the rotational speed of the driving gear 100 as transmitted to the ring gear RG and of the rotational speed of the control shaft 730, imposed by the adjustment motor 700 and transmitted to the star gear SG.
Various modifications and/or improvements may be made to the above-described embodiments without departing from the scope of the invention as defined by the annexed claims.
In particular, while the illustrations of
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