EP1593502B1 - Method and apparatus for the initial control of the adjustement of gravure cylinders of a rotary multicolor printing press - Google Patents

Abstract

The angular displacements of engraved cylinders (C1-Cn) are indexed with respect to reference cylinder. The web length separating printing points of successive cylinders, is divided by peripheral length of cylinder arranged downstream with respect to web traveling direction. Each cylinder is fixed in angular indexing position, and disconnected from common transmission line, after which cylinders are simultaneously reconnected. An independent claim is also included for apparatus for initial adjustment of peripheral register of printing units.

Description

The present invention relates to a method of initial adjustment of the peripheral coincidence of the engraved rolls of successive printing units of a polychromatic rotary printing press according to a given work, these rolls being connected to the same d-tree. by means of respective clutches, according to which an angular mark is placed on each cylinder and aligns this mark with a fixed point relative to the engraved pattern on the cylinder, and these angular positions are measured and stored with respect to a zero point . This invention also relates to a device for implementing this method.

When printing with several engraved cylinders for color printing, it is necessary that the different cylinders are arranged in precisely determined angular positions with respect to one another. This position is a function of the band length between the different printing units and the format of the engraved cylinders, that is to say their peripheral length. If we consider the zero point of the impression of each engraved cylinder, it is necessary to determine its position with respect to the zero position of the other engraved cylinders, as a function of the length of strip separating two successive printing units and the peripheral length of the engraved cylinders, so that the successive impressions of the different colors on the printed strip coincide perfectly.

It has already been proposed in DE 44 41 246 an adjusting device intended to make the respective positions of the different engraved rolls of such a press coincide in each case. which two segments of the drive shaft between two engraved cylinders are connected by a coupling provided with a worm adjusting mechanism capable of modifying the respective angular positions of the two segments of the drive shaft and consequently those of the two engraved cylinders connected to these respective segments.

No. 3,963,902 also proposes a method and a device for replacing the printing cylinders of a polychromatic rotary press driven by a common transmission line, in known angular registration positions for a type working periodically. Once the initial setting of the printing press has been carried out by known conventional techniques, i.e. manual adjustment performed by visually controlling the color match on the printed paper or cardboard web, by means of an angular indexing device, reads the respective positions of the different cylinders and stores them in memory. When the same work is to be performed, the cylinders are replaced in an angular reference position. Then each cylinder is brought to the angular indexing position by means of a differential device driven by a motor which rotates until the angular position of the cylinder coincides with the indexed position. This operation is performed for each cylinder. This adjustment can be made without the presence of a printing tape in the machine which avoids paper or cardboard losses.

The fact remains that this process requires a conventional initial adjustment for each new job and that this setting is time consuming and uses a lot of paper tape or cardboard and in addition the resumption of work involves the semi-automatic positioning done by the operator and which requires some adjustment time on the machine.

A process similar to the previous one but using clutches between each etched cylinder and the transmission line is described in DE 27 53 433.

Another method of adjustment using marks on the engraved cylinders and couplings between the cylinders and a transmission line and which are decoupled from their drives in correspondence with the position of their markings relative to the markings on the chassis for the adjustment of their starting positions is described in EP 0 070 565. This method requires the use of the tape to be printed and therefore a significant loss of material to make the adjustment. In addition, such a method does not solve the question of the initial setting during a first work on the printing press.

The object of the present invention is to overcome, at least in part, the aforementioned drawbacks.

For this purpose, the present invention firstly relates to a method of initial adjustment of the peripheral coincidence of the engraved cylinders of successive printing units of a polychromatic rotary printing press according to a determined work, according to claim 1.

It also relates to a device for carrying out this method according to claim 5.

With the method according to the present invention, it is sufficient to enter in the control programmer of the printing press, the characteristics relating to the work to be performed. On the basis of these characteristics, double-sided work, number and choice of colors, therefore choice of cylinders in work, type of drying, in particular, the path of the band to be printed is defined. So the lengths of the tape between the cylinders are known, which allows to know the relative angular positions of the cylinders, which correspond to the rest of the division of these lengths by the format (peripheral length) of the cylinder. Generally all engraved cylinders have the same format.

On the basis of this information, the initial setting time, for a work performed for the first time on the printing press, of all the cylinders which may comprise, for example, ten cylinders does not exceed 1 minute without any band loss. . This method therefore makes it possible to give exceptional flexibility to the printing press and this not only when it comes to taking over a job for which the initial setting has already been made and has been memorized, but from the initial setting. .

The single figure of the appended drawing illustrates, schematically and by way of example, an embodiment of the method of initial adjustment of the peripheral coincidence of the engraved cylinders of the successive printing units of a polychromatic rotary printing press. function of a determined work.

A full-color rotogravure printing machine comprises a printing line which consists of several engraved cylinders each of which print a different color on a strip of paper or continuous cardboard which is unwound in the machine. At the moment when each cylinder deposits the ink on the support, its color must be perfectly in register with the others. Otherwise, the different colors of the printed pattern are shifted.

The maximum error acceptable for the register between the colors is 0.1 mm when the machine is in production, for the initial setting of the cylinders, object of the present invention, an accuracy of ± 5 mm is acceptable since the system of locating can correct this error through a compensator that changes the tape length between two printing points.

The principle of initial adjustment according to the invention is based on the automatic registration of a point on the engraved cylinders which must be fixed relative to the printed frame on the format. Once the position of this point is located on each cylinder, the automation sequence calculates the displacement to be made on each cylinder to bring it in phase with a reference cylinder which corresponds to the cylinder which prints the first color, this displacement depends the tape path between the engraved cylinders that depends on the configuration given to the machine for a given job.

The machine for carrying out the adjustment method according to the present invention comprises a main motor M which drives a transmission shaft MS. This is connected to each engraved cylinder C1..Cn by reduction gears Z1 / Z2 = 1/3 in this example. A pneumatic clamp CL controlled by a bus coupler BC itself connected to a programmable electronics MCS for the control of the machine, serves as a clutch between the transmission shaft MS and each cylinder C1..Cn.

The shaft of each engraved cylinder C1..Cn carries a CA cam aligned at a fixed angular position corresponding to that of a CR registration mark printed on each engraved cylinder C1..Cn. The angular position of this cam and therefore that of the registration cross CR is detected by an inductive sensor S connected to the same bus coupler BC as the pneumatic clamp CL.

An incremental encoder G is associated with one of the drive shafts of the engraved cylinders C1..Cn. It is a counter at 4096 pulses / revolution, making one revolution per revolution of engraved cylinder C1..Cn. Since all drive shafts of engraved cylinders are constantly rotating and at the same speed, a single encoder makes it possible to know the angular positions of all the engraved cylinders C1..Cn.

Each engraved cylinder prints a registration mark, which is designated RM for the first color which is the reference color printed by the first engraved cylinder C1 and which is designated CM for the engraved cylinder C2. These marks RM, CM are read by RC photocells arranged so that their reading point is at a determined distance PR from the printing point on the engraved cylinder C1..Cn. The strip distance between the respective print points N and R of the engraved cylinder Cn and the reference cylinder C1 corresponds to d (N-R).

LY indicates the distance on the engraved cylinder, between the CR registration mark of each cylinder and the RM, CM reference mark printed on the tape.

The machine comprises for its control an HMI human-machine interface, which may take the form of a control touch screen, connected to the programmable electronics MCS and to the control electronics of the register REG. During printing the REG system uses the incremental encoder G and the photocells RC for reading the registration marks RM, CM printed on the printing tape. A fast bus BUS1 (T = 5msec) is arranged between the bus couplers BC and the programmable electronics MCS and a supervision bus BUS2 is arranged between the programmable electronics MCS and the register control electronics REG. The programmable electronics MCS and the register control electronics REG use the information given by the incremental encoder G.

The main drive motor M of the printing machine is associated with a frequency converter D which receives a control signal CTR of the programmable electronics MCS for machine control. This variable frequency drive is used to control the main motor M in position during the initial calibration process of the engraved cylinders C1..Cn. A GM motor encoder also connected to the MCS control electronics allows vector control, which serves to slave the motor in speed and position.

In the initial preparation phase of the machine for a work done for the first time on this machine, the operator must align the cams CA with the registration cross CR of the engraved cylinder C1..Cn. This operation can be performed once and can be performed outside the machine.

The inking carriage (not shown) is introduced into the machine regardless of the lateral position and the angular position of the cylinders C1..Cn.

Before activating any automatic sequence on the machine, it is necessary to select the characteristics of the work to be done in the machine. For example, we must choose whether the print is front or back, whether the cylinder is active or not, what type of dryer is used, etc. The job information is used to define the passage of the tape to be printed in the machine. They must be entered even on printing groups of cylinders C1..Cn which are not selected and which are between two selected groups. All this information is entered using the keypad constituting the human-machine HMI interface.

The clamps CL of the printing groups of the cylinders C1..Cn selected are closed, so that these cylinders are kinematically integral with the transmission shaft MS, therefore the motor M. The closing operation of the clamps performs the same time the lateral positioning of the cylinders. The lateral positioning of the cylinder allows to bring the support of the cam CA in front of the inductive sensor S. Therefore, once the cylinder starts to rotate, the angular position of the cam CA can be detected by the sensor S. The lateral positioning is done using the ML engine. In this example, this motor is brushless type Eex-d, controlled in position by the programmable electronic control unit MCS of the machine. When the machine is in production this motor Ml is used for the control of the lateral register.

The initial angular setting operation of the engraved cylinders C1..Cn to adjust the peripheral coincidence of the engraved cylinders of the successive printing units can then begin using a central control located near the HMI interface.

The automatic sequence starts with a slow motor rotation to the index of the incremental encoder G which has the effect of zeroing the electronic counting register located in the control electronics MCS. The incremental encoder G follows the angular position of the main axis downstream of the reduction gears Z1 / Z2. This electronic counting register works on each side of the signals A, / A, B, / B and its resolution at the level of the engraved cylinders C1..Cn is 4096x4 = 16384 pulses per revolution of these cylinders. Translated in mm, this resolution is about 0.05mm on the maximum cylinder size. The electronic counting register is reset with the index signal (Z, / Z) after at most one revolution of the cylinders C1..Cn. The incremental encoder G rotates as long as the transmission shaft MS is driven by the main motor M, regardless of whether an engraved cylinder C1..Cn is in use or not in the printing unit where it is mounted.

From the zeroing of the electronic counting register, the reading of the angular positions of the cams CA by the inductive sensor can begin. The angular position of each cylinder C1..Cn is marked at the instant when the cam CA passes in front of the sensor S. The marking operation of all the cams CA must be made in the space of one revolution of the engraved cylinders C1..Cn. The information given by the sensor S of each engraved cylinder C1..Cn goes up to the programmable electronics MCS by the BUS1 fieldbus whose reading period is about 5msec. The bus coupler BC which makes it possible to multiplex the information is located near the sensor S.

When the position of each cylinder is known, the programmable electronics MCS initiates a calculation which determines the phase shift to be given to each engraved cylinder C1..Cn to register it with the reference cylinder C1 which prints the first color. The calculation of successive phase shifts is based on the band lengths between the printing units and on the printed format, that is to say on the peripheral length of the engraved cylinders. The lengths are calculated based on the choices the operator made using the HMI interface keyboard. At each distance between the group N and the reference group R, is associated a phase shift angle to be made on the group N (2 <= N <= Nmax), this angle is proportional to the remainder of the entire division between the distance d (NR) and the format. The result of this calculation is a list of OL values expressed in degrees. The programmable electronics MCS orders the list OL in the increasing direction.

The programmable electronics MCS rotates the main motor M to bring the first engraved cylinder C1..Cn of the list OL in the desired angular position. Once the position is reached, the motor M stops and the clamp CL of the engraved cylinder C1..Cn is opened, as illustrated for the C2 cylinder. As a result, the cylinder C2 is uncoupled from the transmission shaft MS.

The adjustment process continues by positioning all the other engraved cylinders C1..Cn in the order of increasing phase shifts according to the established list OL and using the same procedure as that used for the first engraved cylinder C2. The advantage of this procedure is that the engraved cylinders C1..Cn which have a greater angular displacement to make benefit from the angular displacements of the engraved rolls which preceded them in the list OL. This procedure makes it possible to position all the engraved cylinders C1..Cn in one revolution of the encoder G (3 main motor revolutions). This sequence requires at most a run time of 1 min for a print line comprising 10 selected printer groups.

At the end of the adjustment procedure, all the engraved cylinders C1..Cn are positioned, the programmable electronics MCS determines the final position of the engraved cylinders C1..Cn with respect to the index of the encoder G, this function makes it possible to to know the position of the registration cross CR of each engraved cylinder C1..Cn with respect to the index of the coder G.

The information on the CR position for each engraved cylinder C1..Cn is sent to the register control system REG with the information relating to the distance PR in mm between the printing point of a given engraved cylinder C1..Cn and the reading point of the RC tracking cell associated with this engraved cylinder.

The register control system REG uses the two aforementioned information relating to the position of the CR mark of each cylinder C1..Cn and to the distance PR between the printing point and the reading point, in combination with the knowledge of the distance LY between the printed registration mark CM with respect to the marks CR of the cylinders engraved C1..Cn. This distance LY is introduced by the operator at the time of the configuration of a job. For the tracking system, these three pieces of information are necessary and sufficient to set the opening of a reading window of the register control system REG at the time of the passage of the marks RM, CM on the printed format in the field of view of the RC reading photocells connected to the REG register control system. Calculations of these parameters including sending to the register control system REG through BUS2 require an overall time of less than 2 sec.

After this adjustment, the machine can be turned on, the colors will be in phase and the register control system REG is synchronized to read the registration marks RM, CM in the window set on the passage of these marks in the field of vision of the RC reading photocells.

In the case where the printing machine whose adjustment method has just been described is associated with an in-line cutting module, the cut can be wedged with respect to the printing of the printing machine. The registration of the cutting module will be obtained by the REG register control system of the printing machine using a digital oscilloscope.

The method according to the present invention thus allows initial adjustment of a full color printing machine completely automatically and without tape consumption. The total duration of the implementation of this adjustment operation does not exceed 2 minutes

Claims (6)

1. Method of initial adjustment of the circumferential registration of engraved cylinders (C1..Cn) of successive printing units of a multi-colour rotary printing press according to a specific job, said cylinders being connected to the same transmission line (MS) by means of respective clutches (CL), according to which an angular register mark (CA) is associated with each cylinder (C1..Cn) and said angular positions are measured relative to a zero point and stored, characterized in that the data of the job to be performed is stored, the respective angular displacements of the engraved cylinders (C2..Cn) are indexed relative to a reference cylinder (C1) according to said job by determining the web length separating two printing points of two printing units of two successive engraved cylinders (C1..Cn) for said specific job, the length is divided by the circumferential magnitude of the engraved cylinder arranged downstream relative to the direction of travel of the web and the remaining amount of the division is used to determine the angular indexing, each cylinder (C1..Cn) is then successively brought into its thus fixed indexed position and it is disconnected from the transmission line (MS) and all the adjusted cylinders (C1..Cn) are simultaneously reconnected to the transmission line.
2. Method according to claim 1, according to which before bringing each engraved cylinder (C1..Cn) into its indexed position the indexing values are classified in ascending order and said cylinders are brought into their respective indexed positions according to the succession given by the classification of their indexing values.
3. Method according to any one of the preceding claims, according to which an angular printing mark (RM, CM) characteristic of the angular position of the engraving is associated with each engraved cylinder (C1..Cn), a scanning point is fixed for the angular printing marks (RM, CM) of the engraved cylinders at a determined distance from the printing point of the respective engraved cylinders and this distance is stored, as well as the angular positions of the angular register marks (CR) of the engraved cylinders (C1..Cn).
4. Method according to claim 3, according to which the angular positions are determined of the respective engraved cylinders (C1..Cn) corresponding to the openings of the respective scanning windows at the time of passage of the angular printing marks (RM, CM) of the respective printing units for the synchronised register control, by means of the respective angular positions (CR) of the engraved cylinders (C1..Cn), the distances (PR) separating the printing points of the respective engraved cylinders (C1..Cn), the scanning points of the respective printing marks (RM, CM) and the distances (LY) between the angular register marks (CR) of the respective engraved cylinders (C1..Cn) and the angular printing marks (RM, CM) characteristic of the angular positions of the engravings of the respective cylinders (C1..Cn).
5. Device for implementing the initial adjustment method according to claim 1, comprising a transmission line (MS) driven by a main motor (M), a plurality of engraved cylinders (C1..Cn), clutching devices (CL) to selectively connect the engraved cylinders (C1..Cn) to the transmission line (MS), a register mark (CA) of a determined angular position of each engraved cylinder, a detector (S) of this register mark, an incremental encoder (G) of the angular position of the engraved cylinders, a programmable control (MCS) connected to the incremental encoder (G), to the detector (S), to the clutching devices (CL) and to an interface (MMI) for introducing the operating parameters of the job to be performed.
6. Device according to claim 5, wherein the said programmable control (MCS) is connected to a frequency modulator (D) for the motor (M) and to an encoder (GM) for speed and position control of the motor (M).

Images