The invention is related to a register insertion apparatus for sheet-fed embossing machines according to the generic term (preamble) of claim 1. An automatic register insertion apparatus or register draw-in device of this kind is, e.g., known from EP 0 708 046, resp., U.S. Pat. No. 5,718,057.
Here a not fixed sheet is moved to a desired position by means of position sensors and printing marks controlled by two front stops and a lateral stop, each of which is moved by actuators. This register positioning of a not fixed sheet by means of front- and lateral stops, however, still comprises significant limitations and disadvantages. Above all in the case of higher speeds it is possible that the register movements on a not fixed sheet are not carried out sufficiently rapidly and precisely, because the sheet is increasingly distorted, resp., upset.
Up until now the register positioning of the sheets therefore normally was adjusted and reset manually. A flat bed embossing machine of this kind is described, e.g., in EP 0 858 888.
Therefore it is the objective of the invention to create an automatic register insertion apparatus for higher performance capacities, which overcomes the current disadvantages and with which for each sheet individually optimally and automatically all register errors are corrected and which enables print- and relief images in a constant highest quality.
This objective is achieved by a register insertion apparatus in accordance with the invention according to claim 1.
The dependent claims are related to advantageous further developments of the invention. These concern further improvements of the register functions and -characteristics and they enable a broader field of application and higher machine performance capacities. In the following, the invention is further explained on the basis of examples and Figures.
These illustrate:
a, b, c examples of ventilation openings,
a, b register diagrams with a course over time of the register functions over one machine cycle,
In doing so, the register plate 15 is pivoted down 15′ for the passage of a gripper bar 8, which is connected with a drive chain 32 of the embossing machine 1.
Thereupon the gripper bar is stopped and the register plate is pivoted up again and a sheet 5 is fed on to the register plate from a feeder 3 until it is stopped by the front stops 12. Then the register plate is evacuated for sucking and fixing the sheet 5 on the register plate 15. Subsequently the front stops 12 are lowered (12′) and the register plate is moved in X-direction by the actuators L1, L2 and in doing so the sheet 5 is slid on to the gripper bar 8 and with this also the position of the printing marks P1, P2 on the sheet are detected with the sensors S1, S2 and from this a residual displacement X1, X2 is calculated and the register plate with the sheet is moved into the set position P1S, P2S in X-direction and after the position of the printing marks P1, P2 in X-direction is detected by the sensors S1, S2, the register plate is moved in Y-direction by the actuator L3 into the set position P3S, in that in an analogue manner the lateral edge printing mark P3 is detected by the sensor S3 and a lateral residual displacement Y3 is calculated. After the register alignment has been completed, the sheet 5 is gripped by the stationary gripper bar 8 by means of the gripper clamps being closed. Thereupon the register plate 15 is ventilated and as a result the sheet is released from the register plate, so that it is able to be transported on to the next station (here a flat-bed printing press 2) by the gripper bar 8 over the lowered front stops 12. As will be further explained by means of the
In preference, the register plate 15 is capable of being pivoted down around a pivot axis 16 and moved by a machine drive 30, here, e.g., by means of a radial cam disc 31. This results in a simple, highly dynamic and precise driving of the register plate 15, synchronous with the machine running.
In X-direction the overall displacement X0 (without register correction), e.g., amounts to 9 mm and it may be within a range of, e.g., 5-12 mm In Y-direction the basic displacement Y0 is able to be within a range of, e.g. 4-8 mm and amount to, e.g., 5 mm The overall displacements=basic displacement+calculated residual displacement then are:
X4=X0+X1, X5=X0+X2, Y6=Y0+Y3
It is also possible to enter additional picture-print correction values X1.1, X2.1, Y3.1 into the register controller 11 by hand. Then the overall displacements result as:
X4=X0+X1+X1.1, X5=X0+X2+X2.1, Y6=Y0+Y3+Y3.1.
Correction values of this kind, e.g., may serve to determine differences between an existing picture and a subsequent relief print, which has been applied to the existing picture by eye and to enter corresponding correction values, until reconciliation has been achieved.
The register positioning is also capable of being applied to sheets, which do not have any printing marks P1, P2, P3. Then the front and a lateral sheet edge serve as printing marks, which are detected by the correspondingly adjusted position sensors S1, S2, S3.
In order to achieve high machine speeds and a secure and precise functioning of the register device, the sheet 5 has to be fixed rapidly and without any distortion on the register plate 15, which as a whole is capable of carrying out the register positioning in X- and Y-direction rapidly and precisely, so that the sheet can be transferred to the gripper bar 8 precisely defined in the desired position. For this purpose, the fixing and releasing again of the sheet by means of suction and ventilation has to take place rapidly, in order that as much time as possible is available for the register positioning. With the register insertion apparatus according to the invention, therefore a rapid sucking and fixing of the sheet and a secure adhesion on the register plate 15 (without sliding) is achieved: On the one hand by means of a corresponding construction of the evacuation system with little void volume and a rapid actuation and by means of the arranging and dimensioning of the ventilation openings 20 and supply lines 21 and on the other hand by means of an optimum static friction on the surface 19 of the register plate. The function of a run-in plate 35 with a fixed pivot axis 36 and sliding stones 37 for guiding a sheet 5 running in close to the register plate 15 is further explained with the example of
The
For this purpose, the register plate comprises suction areas B1, B2, . . . with differing, adjustable suction powers and/or with separate vacuum feed lines 21. It is possible that the suction areas differ by:
In doing so, e.g., the areas B1 to B5 and B7 are capable of being ventilated and evacuated and the areas B6 and B8 remaining open (not being evacuated), so that the sheet 5 above all in the most forward area 17 at the front edge 29 is fixed particularly well, rapidly and securely.
The surface 19 of the register plate around the ventilation openings 20 partially comprises an increased static friction, for example, it may be roughened or consist of eloxided aluminium. Above all in the most forward area 17, e.g., on a front suction bar, an increased static friction is strived for. For this purpose, it is also possible that here the suction bar 17 is covered with a layer of rubber 24 (e.g., 0.5 mm rubber coating).
The
In order to be able to align the register plate 15 rapidly and accurately, highly dynamic, precise actuators L1, L2, L3 are utilised, e.g., servomotors with spindles. In doing so, the moving masses of the register plate 15 with its driving device are kept as low as possible, e.g., also by means of an aluminium construction. Advantageously, for this purpose linear motors may be utilised as actuators.
The
The course over time of the register alignment according to
The sheet 5 running on to the register plate 15 is mechanically stopped by the front stops 12, which are attached to the register plate. The sheet reaches the front stop, e.g., at W=185° of the machine position. The register plate at this point in time is approx. 8-10 mm before the theoretical end position (sheet transfer to the gripper bar). Immediately after the sheet arrival time, the register plate is evacuated and the sheet is sucked to the register plate with a vacuum. This produces a non-positive connection between the sheet and the register plate. Subsequently, at the point in time W=225° the actuators L1, L2 commence with their movement in the sheet running direction X. There are two printing marks P1, P2 and a lateral mark P3 on the sheet. The front mark reader, resp., the sensors S1, S2, which are situated at a distance of approx. 10 mm above the sheet, detect the passing printing marks P1, P2. In the register controller 11 the longitudinal mark signals are evaluated and with the two actuators L1, L2 the sheet is aligned in longitudinal direction X. For the complete displacement in X- and subsequently also in Y-direction the actuators have respectively 60° of the machine movement at their disposal. In case of a machine speed of, e.g., 7500 sheets/hour therefore respectively 80 ms for the X- and the Y-positioning result. As soon as the sheet at the front stop has been gripped by the vacuum of the register plate 15 and fixed, the front stop 12 is able to be pivoted down. The starting point for this is at W=240°. The front stop imperatively has to be in raised position again prior to the arrival of the sheet at the front stop at W=185°, e.g., at W=170°-180°. At the machine position W=285° the actuator L3 starts its movement. By means of a lateral mark reader, resp., sensor S3 and by the controller the sheet is laterally aligned in Y-direction. At the point in time W=345° the clamps on the gripper bar close and thus fix the sheet. Subsequently the register plate 15 is ventilated and at the point in time W=360° the sheet must be free for the further transportation by means of the gripper bar 8. In the example of
b illustrates an example, in the case of which the displacements X4, X5 by the actuators L1, L2 in X-direction and the displacement Y6 by the actuator L3 in Y-direction partially take place at the same time, overlapping one another. Here the X-displacement (57a2), e.g., from W=220°-320° (over 100°) and the Y-displacement (58a2), e.g., from 270°-350° (over 80°) take place, wherein the displacements from W=270°-320° take place simultaneously.
Because of this, for each displacement direction X, Y correspondingly more time is available, resp., it is possible to achieve higher machine speeds.
The Y-displacement should only commence, when the position of the printing marks P1, P2 in X-direction has been detected. So that this happens rapidly, the sensors S1, S2 are arranged to be as close as possible to the printing marks P1, P2, e.g., at a distance of 1-3 mm, in preference 1-2 mm Preferably the Y-printing mark P3 should be read by the sensor S3 only when the X-displacements have been practically completed.
The displacements in X- and in Y-direction may also take place at the same time, e.g., in that the sensors 51, S2, S3 detect the printing marks P1, P2, P3 after the standstill of the sheet on the register plate at the same point in time, in that respectively as picture detection the position of a printing mark relative to a fixed reference point on the register plate 15 is detected, from this the residual displacements X1, X2, Y3 are calculated and then the actuators L1, L2, L3 simultaneously move the sheet in X- and in Y-direction into the desired positions P1S, P2S, P3S.
In order to further increase the machine speed, it is possible that the movement 51a of the driving chain 32 also amounts to more than 180°, e.g., 190°-200°, so that the standstill 51b would amount to less, 170°-160° and the further functions 52-58 would be correspondingly adapted.
The
The side view of the register plate 15 according to
Briefly summarised, the sheets 5 shall run-in easily, rapidly and flat right up to the front stops and then, above all in the most forward area 17 shall be rapidly and securely fixed to the register plate by evacuation, so that the register alignment can be carried out rapidly and precisely—without any slipping or arching of the sheets 5.
Within the scope of this description, the following designations are utilised:
Number | Date | Country | Kind |
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1409/06 | Sep 2006 | CH | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/CH07/00430 | 8/30/2007 | WO | 00 | 6/15/2009 |