EP0741001A2 - Stamping, printing and punching machine - Google Patents

Abstract

An embossing press has an upper section (3) supported by the side pillars (6) with a heated (7) tool-plate (4) for the sleeve blocks (8). A positioning mechanism (10) forming part of the head (5,9) comprises a sliding wedge (11) whose location is controlled by a servomotor (20) and screwed shaft (12) giving work-thickness adjustment in the direction (Y). The lower press section (19) is made up of a quadruple 3-link (17) system having a common rotary origin to provide a vertical reciprocating motion (H) to the table (13) carrying the work platen (14) and embossing surface (F). The pressure sensors (51 to 54) or (55 to 58) signal the controller (2) in response to a programme (30) selected by the input unit (40) to enable performance monitoring and in-process correction where required.

Description

The invention relates to an embossing printing and punching machine according to the preamble of the independent claim. In such machines, pressure force measurements are usually only known at one point on the machine and outside the embossing pressure area. On the one hand, this requires complex conversions depending on the position of the clichés to estimate the pressure forces on the embossed image area. Moreover, these force measurements are inaccurate and unreliable. Influences that change the working pressure and thus deteriorate the print quality can therefore not be recorded well and the change in the course of a work process can be compensated even less. Uneven pressure distributions on the embossed printing area cannot be recorded.

It is therefore an object of the present invention to provide an embossing printing and punching machine which enables precise detection of the pressure forces and thus also the setting of an optimal embossing quality and which, above all, can largely compensate for the negative influences and changes during operation, so that constant top quality is achieved.

This object is achieved by an embossing printing and punching machine according to the invention. The arrangement of a plurality of pressure sensors around the embossing printing surface enables precise determination of the pressure force and monitoring. The combination with the positioning device with controlled slide drive, with the pressure control program and the operating and display device makes it possible to set optimal working pressures and to maintain them constantly and optimally even under negative influences during operation.

The dependent claims relate to advantageous developments of the invention, which further automate, improve and make their function simpler and more reliable. Particular advantages lie in the automatic execution of operations such as touching, keeping the working pressure constant and being able to drive almost any programmable pressure setpoint curve. The machine according to the invention enables compliance with safety and limit values as well as the detection of uneven, eccentric pressure distribution on the embossed printing surface. Above all, however, the various variable influences on the working pressure that worsen the quality, e.g. as a result of thermal influences or increasing, permanent deformation or change in thickness of the dressing and as a result of fluctuations in the paper thickness. This enables the highest possible and constant embossing quality to be achieved with minimal operating effort and with the greatest possible security.

Fig. 1a

eine erfindungsgemässe Maschine

Fig. 1b, 2

Anordnungen von Druckkraft-Sensoren und exzentrische Belastungen

Fig. 3

ein Schaltschema der Maschine

Fig. 4

Druckkraft-Verschiebungs-Charakteristiken X(Y)

Fig. 5

Beispiele verschiedener Druckkraftwerte

Fig. 6

verschiedene Einflüsse auf die Druckkraft-Verschiebungs-Charakteristiken

Fig. 7

Beispiele zeitlicher Druckkraftverläufe X(t)

Fig. 8

programmierbare Sollwertverläufe der Druckkraft XX(t)

In the following, the invention is further explained with the aid of examples and figures. Show it:

Fig. 1a

a machine according to the invention

1b, 2

Arrangements of pressure force sensors and eccentric loads

Fig. 3

a circuit diagram of the machine

Fig. 4

Push Force Displacement Characteristics X (Y)

Fig. 5

Examples of different compressive force values

Fig. 6

different influences on the pressure force displacement characteristics

Fig. 7

Examples of temporal pressure force curves X (t)

Fig. 8

Programmable setpoint curves for the pressure force XX (t)

1 a shows a side view of an embossing-printing and punching machine 1 according to the invention with an upper press part 3, which is held by side supports 6, with an upper support 5, a positioning or displacement device 10 and a press head 9. This head 9 carries a tool - Or Clichéplatte 4 with a heater 7, which includes, for example, several individually adjustable heating zones.
A lower press part 19 here has a toggle lever mechanism with four toggle lever pairs 17, which move a press table 13 up and down by a stroke H of, for example, 80 mm. A counterpressure or dressing plate 14 is attached to the table 13, the surface of which forms the embossing printing surface F (ie the maximum usable embossing surface). Clichés 8 are attached to the tool plate 4, the surfaces of which define the embossed image area FC (see FIGS. 1b and 2). A dressing 15 adapted to the clichés 8 is inserted on the dressing plate 14, which consists, for example, of a 1-2 mm thick, fabric-reinforced plastic plate, of hard laminate, for example Pertinax, or of less hard material such as pressboard or unreinforced plastic. The material and layer thickness are adapted to the clichés and the embossed goods. By locally placing thin layers of paper, for example 20 µm thick, the preparation is adjusted in a known manner to optimal embossing quality.

The optimum embossing pressure or the embossing pressure force X is set by moving the positioning device 10 in the Y direction. A controlled adjusting motor, e.g. a servo motor with an incremental encoder and an associated motor control 21. The displacement Y takes place via a transmission 16 to a spindle 12 which moves a displacement wedge 11. The maximum possible displacement range of Y is e.g. 4 mm, which makes it possible to compensate for different layer thicknesses of dressing and embossing.

As shown in FIG. 1b as a partial representation of the machine 1 from above, a plurality of pressure force sensors S1 to S4 or S5 to S8 are arranged around the center Z of the embossing pressure surface F of the plate 14. The pressure force measurement takes place e.g. by means of strain gauges such as strain gauges (DMS) or piezo elements, which are attached to suitable chassis elements of the machine that experience significant strains under load. As an example, strain gauges S1 to S4 are attached to the side supports 6 here. These could also be attached to the press head 9. However, the pressure forces can also be recorded with pressure cells S5 to S8, which e.g. are arranged in the four corners each under a toggle lever 17, as shown in Fig. 1a. This rectangular arrangement of the force measuring sensors S1 to S4 or S5 to S8 around the center Z of the embossing pressure area F makes it possible to compensate for eccentric loads from the embossing image area FC, i.e. due to the location of the Clichés 8, easy to detect and monitor.

. Als maximal zulässige Werte für eine gegebene Maschine wird z.B. ein Sicherheitswert XM = 1500 kN fest eingestellt, sowie für jeden Einzelsensor ein Sicherheitswert XMi = 450 kN. Im Betrieb müssen immer alle Sicherheitswerte XM und XMi eingehalten werden.FIG. 2 shows a further example with a triangular arrangement of the sensors S9 to S11 and an eccentric arrangement of the clichés or the embossed image areas FC1 and FC2, which result in a greater load on the side of the sensor S9. By detecting and monitoring uneven In particular, damage to the press can be avoided. In this way, each individual sensor can be assigned a safety value XMi as the maximum permissible value and its compliance monitored. The total compressive force X is determined from the measured values of the sensors S1 to S4, that is to say from the partial compressive forces XSi (for example according to FIG. 1a) by superposition: $\text{X = XS1 + XS2 + XS3 + XS4}$

. For example, a safety value XM = 1500 kN is permanently set as the maximum permissible values for a given machine, and a safety value XMi = 450 kN for each individual sensor. All safety values XM and XMi must always be observed during operation.

FIG. 3 shows a circuit diagram of the machine according to the invention with pressure force transducers S1 to S4, which are connected to the pressure controller 30 or the machine controller 2. The positioning servomotor 20 with motor controller 21 is also connected to the machine controller 2 and the pressure controller 30. To the operating and display device 40, which e.g. is designed as a touch screen, bidirectional communication takes place with the controls 30 and 2. A further output 35 can additionally be provided for the bidirectional connection to an external computer, e.g. with a PC, to output operating data and to enter additional functions.

FIG. 4 shows a characteristic X1 (Y) that is valid for a specific dressing, ie the pressure force X1 generated on the embossed product as a function of the displacement Y by the press. This characteristic can be driven and recorded automatically if, for example, the following function is entered in the control program:

Increase displacement Y linearly as a function of time until the compressive force value X1 has reached a given value Xmax.

Es muss also der Kopf 9 um den Bereich Y12 nachgestellt werden.This characteristic X (Y) is of course dependent on the clichés and the finish (type of material, thickness and size), ie it characterizes this finish and this specific embossing process. In the course of operation, this characteristic X (Y) of a given dressing changes gradually, for example from curve X1 (Y) in the initial state to curve X2 (Y) after a certain running time, because the dressing wears out or is compressed more and more over the course of time an embossing. This must be compensated for by a correspondingly larger displacement Y in order to achieve the same pressure force value X, for example the working value XA: from YA1 to YA2 with $\text{YA2 = YA1 + Y12}$

The head 9 must therefore be readjusted around the area Y12.

Further influences which cause a change or a shift in the characteristics X (Y) are discussed with reference to FIG. 6.

FIG. 5 shows the course of pressure measurement signals as a function of time t: X1 (t). Over a machine cycle of 360 °, in which the toggle press carries out a stroke H, the press is only under pressure for approx. 20 ° - 25 ° (area on-pressure, on-press). The press does not exert any pressure during the entire remaining time of 335 ° - 340 ° (X = 0, area Ab-Druck, off-press). The pressure curve has a broad maximum at top dead center OT. The displacement in Y by the adjusting device 10 always takes place without pressure (ie in the area of pressure). During this time, the zero points of the sensor values are also readjusted (adjustment of a zero point drift of the measurement signals, for example as a result of thermal influences on the sensors). With each press stroke, the effectively exerted pressure force X is determined as the difference between the measured values between top dead center OT and the pressure area. A certain tolerance range can also be provided and monitored for this adjustment of the zero point drift of the sensor measurement signals: System limit values of the zero point, if exceeded, error messages are issued.

The pressure force curves X1, X2, X3, X4 (t) shown as examples - corresponding to different displacement values Y1, Y2, Y3, Y4 - illustrate different embossing cycles.

Here X1 corresponds to the work value XA, at which the optimal embossing quality is achieved. An adjustable and selectable tolerance + XT, -XT is assigned to this work value XA.
The curve with compressive force value X2 is below the tolerance range XA - XT,
the value X3 lies above the tolerance range XA + XT
and the curve with pressure force value X4 corresponds to the safety value XM, ie the maximum permissible press pressure.

The tolerance value XT is e.g. adjustable between 10 - 100 kN. This tolerance range is only used, however, if the operating mode - "REG" = keep work value constant automatically - is not used; because there is regulated XT with a much smaller control difference DX within this tolerance range (see FIG. 7).

FIG. 6 illustrates various influences which cause changes over time in the characteristic Y (X) (FIG. 4) or changes in threshold values Y0 (t) and work values YA (t) for given constant compressive force values X0 and XA: This is done with the curves Ytemp, Yzu and Ypap are shown.

When the machine is heated up, different thermal expansions occur, which result in corresponding changes in the distance between the tool plate 4 and the dressing plate 14. This shows the Ytemp curve.

Continuously progressive wear and permanent compression of the finish 15 causes e.g. a course according to curve Yzu. If the dressing is changed (the Y value is adjusted), a shifted curve Yzu2 results.

Fluctuations in the paper thickness have a further influence on the shift values Y0 and YA (t), as illustrated by the curve Ypap. The superposition of all these influences Ytemp, Yzu, Ypap etc. ultimately results in the resulting overall change in the characteristic X (Y) over time. This corresponds e.g. curve X6 (t) in FIG. 7.

A wide variety of operating modes are possible with the machine according to the invention. These are stored as functions in the print control program 30 and can be selected via the operating and display device 40, or can also be entered externally via the output 35. In this way, the most varied of operating parameters relating to an embossing print job as well as limit values, tolerances, switching values and programmed setpoint curves (see FIG. 8) can be entered or reprogrammed.

A practically important example is the automatic execution of an operating mode or function "TOUCH" = touch: the press is brought to the top dead center OT and stopped. The pressure measurement takes place continuously and no longer cyclically as during normal operation of the machine in the "RUN" mode (see Fig. 5). In this position T T the adjustment device 10 is now automatically shifted, ie Y is increased until a pressure increase is measured. If a minimum adjustable pressure threshold X0 is reached, the shift Y is stopped and the corresponding value Y0, ie this position, is saved. This is shown in Figure 4. The pressure threshold is, for example, X0 = 5 - 10 kN, ie around 1% of the working value XA.

definiert und fixiert. Dann wird die Funktion "REG" angewählt, womit dieser Arbeitswert XA im folgenden automatisch konstant, d.h. innerhalb einer engen Regeldifferenz DX, gehalten wird.A particularly important function "REG" is to keep the work value XA, ie the optimal pressure force for the highest quality of a given print job, automatically and precisely constant. For this purpose, the work value, which gives an optimal embossing image, is first determined by varying the pressure force X. This value is called the labor value $\text{X = XA}$

defined and fixed. Then the "REG" function is selected, with the result that this work value XA is automatically kept constant in the following, ie within a narrow control difference DX.

This process takes place e.g. according to the following scheme "REG":

mit dem $\text{Istwert = Mittelwert Xm}$

verglichen:
Wenn die Abweichung Xm - XA grösser ist als die Regeldifferenz DX,
dann erfolgt eine Nachstellung von Y um einen Nachstellschritt DY.
Zusätzlich wird geprüft, ob der Nachstellbereich YN überschritten ist, worauf allfällig ein Signal ausgegeben und die Maschine gestoppt wird.
Anschliessend erfolgt eine neue Mittelwertbildung Xm.When the pressure measurement is set to "RUN" operation
and the "REG" key is pressed
and the Y adjustment is released,
then the setpoint $\text{Xset = XA}$

with the $\text{Actual value = mean value Xm}$

compared:
If the deviation Xm - XA is greater than the control difference DX,
Y is then adjusted by an adjustment step DY.
In addition, it is checked whether the adjustment range YN is exceeded, whereupon a signal is output and the machine is stopped.
This is followed by a new averaging Xm.

beträgt.In order to avoid unnecessary constant back and forth regulation, the actual value of the regulation is preferably continuously as the mean value Xm from the n-last ones Pressure force measurements determined. For example, n = 5, which is the mean
$\text{Xm = 1/5 of the sum of the last five measured values X}$

is.

The control difference DX is e.g. 5 - 10 kN and the regulation adjustment step DY e.g. 1 - 2 u.

For further monitoring of an embossing job, an adjustment range YN can be selected and entered by e.g. YN = 0.1 mm. As soon as the automatic tracking of Y reaches this value (e.g. YA1 + YN in Fig. 4), a signal is output and the machine is stopped if necessary. Then the operator can decide whether to continue beyond this adjustment range YN - by specifying a new second adjustment range of e.g. 0.05 to 0.1 mm - or whether the dressing should be changed and restarted.

Another important safety function is achieved with the "automatic printing" mode. The sheet entry into the press is monitored. If no incoming sheet is detected, the shifting device 10 is immediately moved in the direction -Y, e.g. 1 mm, retracted (according to arrow R in Fig. 4) before the next stroke of the toggle press. This prevents the finish 15 from being embossed when no sheet is running in.

The advantages of this automatic regulation of the work value are further illustrated with FIG. 7, which shows different temporal pressure force profiles X (t). As explained above, the curve X5 (t) runs according to the "REG" mode in a narrow control range between an upper limit value XA + DX and a lower limit value XA - DX. Here is regulated to constant pressure.

In contrast, curve X6 (t) shows the pressure force curve if the displacement Y is kept constant. The influences explained in FIG. 6, or changes in Y by temperature, dressing and paper thickness, result in a corresponding, significant change in the resulting pressure force X6 (t) with a constant displacement Y. Until now, these influences had to be continuously monitored and monitored by the machine operator periodically be compensated by hand by tracking the displacement Y, which corresponds to the curve X7 (t). This was very complex and moreover inaccurate, so that practically only an effectively driven curve X7 (t) with significantly fluctuating pressure force values was achieved.
The resulting embossed print quality is of course much better in accordance with the new curve X5 (t) with automatic constant control than in the curve X7 (t) that was previously achievable. In addition, operating errors can also be avoided with the automatic functions and controls of the machine according to the invention.

However, the pressure force curve X (t) that is driven can not only be kept constant automatically according to the "REG" curve, but in principle it can also be regulated according to any predefined setpoint value curves for the pressure force XX (t) by correspondingly adjusting the displacement Y. Figure 8 illustrates two examples. Curve XX1 shows a rapid increase, followed by a slow decrease and finally ending in constant pressure. Operating mode "REG". According to curve XX2, the compressive force is gradually increased, e.g. from X = 600 kN each 20 kN to 700 kN is reached. In this way, for example, 20 identical test prints can be automatically generated with the machine for each stage. This can result in the best print quality optically determined and the corresponding pressure value selected as the work value XA.

Suitable setpoint specifications XX (t) or controlled displacement functions Y (t) can e.g. optimal parameters for the characterization of embossing orders are determined automatically, more precisely and more comprehensively

Claims (14)

Embossing printing and punching machine with a machine control (2), an upper press part (3) with tool plate (4) and positioning device (10) and with a lower press part (19) with counter pressure plate (14), characterized in that several pressure sensors (S1 - S4 ) for the measurement of pressure forces X around the center Z of the embossing pressure surface F, the positioning device has a displacement drive (20) with an associated motor control (21), which is connected to a pressure control program (30) with functions (REG) for pressure force control and to which an operating and display device (40) is assigned. Machine according to claim 1, characterized in that four pressure sensors (S1 - S4), each assigned to a corner of the embossing printing surface F, are arranged on the machine. Machine according to claim 1, characterized in that strain gauges (strain gauges) are attached to load-bearing parts (6) of the upper press part (3) as pressure sensors. Machine according to claim 1, characterized in that the positioning device has a sliding wedge (11) and a regulated adjusting motor or servo motor (20). Machine according to claim 1, characterized in that the pressure control program (30) has different operating modes (REG, TOUCH) which can be selected on the operating device (40). Machine according to claim 1, characterized in that the pressure control program (30) has a "touching" (TOUCH) function. Machine according to claim 1, characterized in that the pressure control program (30) has a function "keep work value constant" (REG). Machine according to claim 1, characterized in that the pressure control program (30) has a function "control pressure setpoint curves (XX1, XX2)". Machine according to claim 1, characterized in that the pressure control program has predeterminable pressure difference values (DX) and / or readjustment steps (DY) for regulating the pressure force value X. Machine according to claim 1, characterized in that the pressure control program contains fixed or predefinable safety values (XM, XMi), limit values and / or tolerance ranges (XT). Machine according to claim 1, characterized in that the pressure control program contains specifiable switching values (XT, DY), in which secondary functions such as machine stop or warning signals are triggered. Machine according to claim 1, characterized in that the pressure control has a three-point control, with a control difference DX and a displacement adjustment step DY, the actual value being continuously formed as the mean value Xm from the last n pressure measurements. Machine according to claim 1, characterized in that a selectable adjustment range YN is adjustable, the achievement of which triggers a signal. Machine according to claim 1, characterized in that the pressure control has a bidirectional output (35) for an external computer.

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