EP0893255B1 - Method and device for positioning an actuator of a printing machine - Google Patents

Description

The invention relates to a method and a device for positioning a Actuator of a printing press according to the method or device claim.

Printing presses have a large number of remotely adjustable devices, such as dosing devices for dampening solution, ink, varnish and remotely adjustable Register adjustment devices. Together in such remote adjustable Actuators is that the member to be adjusted (e.g. doctor element, Color metering element, divided or undivided color meter) an electrically controllable Motor is assigned, which acts on it via an actuating gear. A current position of the link to be adjusted is indicated by an assigned one and, for example, position sensor integrated in the adjustment gear. In one The position signal is evaluated for the controller assigned to the motor the position sensor and the control of the motor to start a predetermined Position. It can be the case with position transmitters (position signal transmitters) are non-contact probing sensors or potentiometers. The one Motors assigned to the actuator are preferably designed as stepper motors. The accuracy of the positioning process of a remotely adjustable actuator depends on the accuracy (resolution) of the signal transmitter (position transmitter) as well on the rate at which the signals are acquired and processed by the controller become.

The zone-wise setting of the layer thickness profile on a rotating one Ink fountain roller takes place, for example, via individual ink metering elements, metering eccentrics or parts of a divided or undivided color knife. An exact ink feed setting is therefore only guaranteed if the advertisement is displayed on a Ink remote control panel exactly with the ink metering element on the ink fountain roller set ink layer thickness matches. For remotely adjustable Devices for dosing dampening solutions or lacquer apply accordingly.

For this purpose it is customary from time to time to use the individual color metering elements or other dosing devices all the way to the rotating ink fountain roller to be adjusted (e.g. manually) and in this position by the position transmitter tapped signal as zero signal for the further positioning operations evaluate. This signal is stored and is used in conjunction with the signals of the position transmitter and / or the control motor sent control signals (Stepper motor operation) for the further positioning processes as a reference value.

From DE 39 14 831 C2 it is known to completely apply a color metering element to the To prepare ink fountain roller, the signal of the trained as a sensor Positioner is permanently checked for changes in time. Know this signal changes over time as long as on the color metering element assigned actuator is in motion, this is an indication that the Ink metering element is not yet on the surface of the ink fountain roller. If the sensor signal does not change over time, the color metering element has (whose tip) reaches the surface of the ink fountain roller and the assigned one The engine is switched off. The current voltage of the position transmitter is saved for further positioning operations. Such an approach requires however, a very high read and evaluation rate of the position transmitter signal or sensors. Should a color metering system with a number of individual Dosing elements assigned to color dosing zones are equipped accordingly because of the hardware requirements, this is cost-intensive.

DE 195 43 364 C1 describes a method and a corresponding device known for positioning actuators within a printing press, in which the actuator to be positioned is initially in an area without contact with the stop (the metering roller) and then in an area with permanent Contact with the stop (the metering roller) is moved. During the Procedure, i.e. during the corresponding servomotor with the intended Motion commands is applied, the of the Position transmitter delivered signals. The detected position transmitter signals are in the respective area as a function of the given movement commands shown, i.e. it becomes both in the area with and in the area without Contacts to the stop each have a position transmitter movement signal function educated. As the zero position of the actuator, that value of the Drive supplied motion command determines which is calculated by Identify the functional relationships determined in the two areas results. In one embodiment of this previously known method provided the position transmitter movement command function as one each linear relationship and set the zero position of the actuator Identify equations of the two systems of equations. According to further training the method provides that after capturing and storing a first zero position the actuator by specifying appropriate movement commands back into the area without permanent contact with the stop (Dosing roller) is moved and then the actuator is moved again towards the stop with simultaneous evaluation of the encoder signals. The position transmitter signals are recorded and stored with the previously stored ones Comparing signals according to functional relationship to form a difference.

The object of the present invention is therefore a method and a corresponding one Device for positioning an actuator according to the preamble of the method or device claim to expand such that Actuators can be moved to a zero position with improved accuracy can.

This task is solved by the characteristic features of the method or device claim. Further developments of the invention result from the respective subclaims.

The invention is especially for a remotely adjustable color / moisture / or Paint dosing device ensures that the individual dosing elements except for the detection of the zero position in the subsequent positioning processes (Doctoring the paint or varnish) not with too much force against the Duktor or the metering roller are turned on. By the invention Method and the appropriately trained device, it is possible that as the zero position that position is detected in which the actuator is one mechanical contact with little force to the stop or to the roller having. For color dosing elements which have a rotating duct (Ink fountain roller) interact as a stop, this means that as a zero position that position can be detected and saved for the further positioning processes is where the paint is being scraped off and the surface the ink fountain roller runs smoothly.

The method according to the invention and the correspondingly designed device is not just about placing a dosing system for paint, varnish or Dampening solution suitable, but any actuators can be positioned, which to obtain a zero position by evaluating a corresponding Signals must be driven once against a corresponding stop. If the actuator is designed as a color metering element, as in the exemplary embodiment, the stop is the rotating doctor in particular or the ink fountain roller. In a similar way, however, there is also a zero position a register actuator can be detected. In this case, for example Adjustment gear via which the motor acts on the register device frame-fixed stop is provided, against which a moving with the register Gear part is driven. Here too, the invention ensures Method and the appropriately trained device that one electrically detectable position of the position transmitter is evaluated as a zero position which corresponds to a light touch of the stops.

Fig. 1

die Signaländerung des Stellungsgebers aufgetragen über den Motorschrittwerten als Bewegungsbefehle,

Fig. 2

ein an einem Farbdosierelement angebrachter Lagegeber, und

Fig. 3

der mit dem Farbdosierelement zusammenwirkende Sensor im Detail.

Furthermore, an embodiment of the invention is explained with reference to the drawing. It shows:

Fig. 1

the signal change of the position transmitter plotted against the motor step values as movement commands,

Fig. 2

a position sensor attached to a color metering element, and

Fig. 3

the sensor interacting with the ink metering element in detail.

Fig. 2 shows a roller 1 rotating in the direction of the arrow and an in radial direction of the roller 1 movable metering element 2. The adjustment movement of the metering element 2 is indicated by the double arrow. The Dosing element 2 is assigned a motor 4 designed as a stepper motor, the movement thereof via a control gear 3 designed as a spindle drive Dosing element 2 for setting color, wet or lacquer layer thicknesses the surface of the roller 1 is transferred.

The signals from a motor controller 5 can be supplied to the motor 4 as a controller. When the motor 4 is designed as a stepper motor, the motor controller 5 is as Stepper motor control trained. The engine control 5 takes place in this If the current is applied to the windings of the motor such that the rotor of the motor 4 is rotated by a corresponding number of angular steps. With the Motor controller 5 is operatively connected to a position transmitter 6 designed as a sensor, the signals can be fed according to the position of the metering element 2 are. The position transmitter 6 is a contactless position of the metering element 2 sensing sensor formed, a preferred embodiment of the invention is shown in FIG. 3. The engine control 5 also has an evaluation circuit by means of which the signals of the position transmitter 6 detectable and evaluable in the manner explained below are.

Since the motor 4 is designed as a stepper motor, positioning operations of the Dosing element 2 via a stepwise control by means of the motor control 5 generated. The engine control 5 is connected via a bus, not shown the electronics of a remote control unit in connection via which target values for Positioning processes can be entered. According to the linearity of the between Motor 4 and metering element 2 interposed adjusting gear 3 causes a certain number of motor steps of the motor 4 that the top of the Dosing element 2 a certain distance on the surface of the roller 1st moved to or away from this.

The signal from the position transmitter 6 is used to find the zero position of the Dosing element 2 trained actuator used. The zero position is then in the controller of the motor control 5 as the count of the step control for the further positioning processes are saved.

A setting of a desired gap between the tip of the metering element 2 and the surface of the roller 1 is now carried out in such a way that the Motor control 5 the motor 4 by a certain number of steps - starting from the current position of the metering element 2 in connection with the current meter reading with the stored counter value corresponding to the zero position. Depending on the direction of rotation of the motor 4 increases / decreases during the positioning process the one corresponding to the current position of the dosing element Value of the counter in the motor control 5.

Fig. 3 shows a preferred embodiment of the metering element 2 with the attached Position transmitter 6. Fig. 3 shows the metering element 2 in a view 2 from above. A movement of the metering element 2 on the The surface of the roller 1, not shown here, takes place via a linearly movable Shaft 8, at the end of which the metering element 2 is attached. The Shank 8 can be an extension of a spindle drive, not shown of the actuator 3 (Fig.2).

At the end of the shaft 8, a ring magnet 7 is attached. This ring magnet 7 leads the movement of the shaft 8 and thus also the movement of the metering element 2 in an analogous manner. At a distance from the ring magnet 7 is here not shown and the actuator 3 and the motor 4 (Fig. 2) bearing Housing a position transmitter 6 attached in the form of a Hall probe. A movement of the metering element 2 and thus the ring magnet 7 relative to the Hall probe thus causes a change in the voltage that can be tapped at it.

The method according to the invention is explained with reference to FIG. 1. First, the motor control 5 moves the metering element 2 via the motor 4 by specifying a number of motor steps M, for example starting from the point P ₁ , in the direction of the surface of the roller 1. The position transmitter signals S which can be detected by tapping the signals of the position transmitter 6 are acquired for the respective current motor steps M. When the metering element 2 is closed in the direction of the roller, the characteristic curve K shown in FIG. 1 results, which represents the relationship between the position transmitter signals S and the associated motor step values M.

It can be seen in FIG. 1 that the characteristic curve K in the area between the points P ₁ and P ₂ and beyond the point P _{3 can} each be approximated as a straight line. In these areas, the metering element 2 either has no contact with the surface of the roller 1 or the metering element 2 is in constant contact with the surface of the roller 1, that is to say it is pressed onto the roller 1 via the motor 4 and the gear 3. In a region between the points P ₂ and P ₃ , the characteristic curve K consequently has a curved course, which is due to the fact that the elements (gear 3) located between the motor 4 and the tip of the metering element 2 are elastic to the forces of the motor 4 react.

After the metering element 2 has been moved in the manner indicated above by means of a corresponding movement command command of the motor step values M to the motor 4 in the direction of the roller 1 and accordingly the individual position transmitter signal values S have been recorded (stored) as a function of the motor step values M, the metering element 2 becomes in again positioned at a distance from the surface of the roller 1, for example again in the point P ₁ . This point P ₁ has the coordinates S ₁ , M ₁ in the coordinate system of the characteristic curve K defined by the axes S, M. On the basis of the coordinates of the point P ₁ in connection with a further point (auxiliary point) on the characteristic curve K spaced from the point P ₁ , the slope of the characteristic curve K in this point P ₁ can thus be determined or the characteristic curve in the point P _{1 can be assigned} an increase. According to the invention, it is now provided that an auxiliary characteristic curve HK is set through this point P ₁ characteristic curve K, the gradient of which is less than the value of the increase in the characteristic curve K at point P ₁ by a predetermined amount. In accordance with the laws of a straight line equation, this auxiliary characteristic curve HK intersects the characteristic curve K at a point P ₃ .

Now, in a second positioning operation, the dosing 2 becomes driven by appropriate presetting of motor step values M, starting from the point P ₁ back onto the roll 1 and the current values of the signals S detected of the position sensor 6 to the respective predetermined motor step values M. The current signal values S supplied by the position transmitter 6 are compared with those signal values S 'which result from the auxiliary characteristic curve HK (straight line equation) for the respective motor step value M. The difference between the signal values ΔS is continuously formed. In Fig. 1, above the characteristic curve K, the course of the erS resulting during this movement of the metering element 2 with respect to the roller 1 is outlined.

When the metering element 2 is moved in the direction of the roller 1, the differential position transmitter signals ▵S have a course which, starting from the point P _1, initially increases gradually and then decreases again after a maximum difference value. In Fig. 1 it is shown that the maximum of the position transmitter difference values ▵S lies at point P ₂ and - since the auxiliary characteristic curve HK intersects the actual characteristic curve K at point P ₃ - at point P ₃ becomes zero again and from there negative values assumes.

According to the invention, that value of the motor step value M (in this case M ₂ ) is evaluated as the zero position value of the metering element 2 with respect to the roller 1, at which the position transmitter difference values ▵S assume their maximum value. According to the exemplary embodiment of the invention explained above, this is the case at the point at which the actual characteristic curve K has the greatest distance from the auxiliary characteristic curve HK.

Generally speaking, in the procedure of the invention explained with reference to FIG. 1, during the movement of the metering element 2 onto the roller 1, at least one point of the characteristic curve K defined by the movement commands M and the position transmitter signals S is at least one auxiliary characteristic curve which deviates from it HK is determined and the value of the movement command to be used for the further positioning processes is determined as the zero position of the actuator from the values and / or the course of the at least one auxiliary characteristic curve HK. In the exemplary embodiment explained above, the signal values S of the position transmitter 6 at the current motor step position M were compared with the position transmitter signals S resulting according to an auxiliary characteristic curve HK, this auxiliary characteristic curve HK being formed as a straight line equation by a point P _{1 of} the characteristic curve K, which is a slight one has a smaller increase (differential) than the current characteristic curve K in this point. It is also possible to generate further characteristic curves (regression lines) from a characteristic curve K that can be determined during a movement process of the metering element 2 in several points, which can be found or found relatively reliably Allow confirmation of a found break point (zero position). The point of breakdown (point P ₂ according to FIG. 1) is the point at which the signals S of the position transmitter 6 leave the linear course due to the beginning contact of the metering element 2 with the roller 1.

As already indicated above, it is possible to apply the principle of linear regression. Here, an optimal straight line is determined for a number of points. With such a calculation, the quantities arise: rise m, absolute term n, correlation coefficient r and the scatter s ² .
With this procedure, a number x points on the characteristic curve K each create a straight line (regression line). If the regression line is placed through a number of points of the characteristic curve K that lie ideally on a line, the correlation coefficient has the value 1 and the scatter has the value 0. This fact can be used to determine the transition from the straight course of the characteristic curve K to the curved course, that is to say that point P ₂ which is to be regarded as the zero position of the metering element 2 for the further positioning processes. For this purpose, a number of x consecutive points is selected from the points of the characteristic curve K which result when the metering element 2 is moved in the direction of the roll 1. The number x of the selected points depends on the curvature of the characteristic curve and should be chosen so large that the curved course and thus the point P2 (zero position) can lie within x successive points. Linear regression is then performed using the number of points set. The starting point of the number of selected points is now changed in succession from the first point to the last possible point on the characteristic. Each time, the regression is carried out and the variables rise m, absolute term n, correlation coefficient r and scatter s ^{2 are} determined and stored. These values are assigned to the starting point. In other words, this approach could be called sliding linear regression.

Now that all the previously defined points have been used to form a linear regression, a point can now be determined at which the rise m and the absolute term n disappear (= 0). At this point, the correlation coefficient r becomes unequal to 1 and the scatter s ² unequal to zero. At this point x-1 points have to be added up. The break point is located there. The motor step value M which can then be assigned to this point is consequently used as the zero position for the further positioning processes.

Reference list

1

roller

2nd

Dosing element

3rd

Actuator

4th

engine

5

Motor control (controller)

6

Position transmitter

7

Ring magnet

8th

shaft

M

Motor step value (motor 4)

s

Position transmitter signal (position transmitter 6)

ΔS

Differential signal

K

curve

HK

Auxiliary characteristic

Claims (12)

1. Process for positioning a remotely controllable adjustment member of a printing press, particularly for positioning metering elements (2) for ink, damping-agent or varnish feed relative to a turning roller (1), in which the adjustment member (2) is moved by the provision of movement commands (M) in the direction of a stop (1) and from the profile of the signals of the position sensor (6) a null position is determined in which the adjustment member (2) lies against a fixed stop (1) and this null position is used for the further positioning processes, characterised in that during the movement of the adjustment member (2) in the direction of a stop (1) at at least one point (P1) of the characteristic curve (K) defined by the movement commands (M) and the position sensor signals (S), an auxiliary characteristic curve (HK) in the form of a straight line is determined, the inclination of which is less than the value of the characteristic curve (K) at point (P1) and that as a null positioning value that value of the movement commands (M) is used at which the position sensor difference value (Δs) between characteristic curve (K) and auxiliary characteristic curve (HK) adopts the maximum value.
2. Process according to Claim 1, characterised in that the value of the movement command (M) to be used for the further positioning processing is determined as a null position of the adjustment member (2) from a comparison of values of the position sensor signals (S) of at least one auxiliary characteristic curve (HK) the corresponding. values of the characteristic curve (K).
3. Process according to Claim 2, characterised in that at at least one point of the characteristic curve (K), an auxiliary characteristic curve (HK) is determined in the form of a straight line with differing gradient.
4. Process according to one of Claims 1-3, characterised in that the value of the movement command (M) to be used for the further positioning processes is determined as the null position of the control member (2) by means of regression lines defined by points on the characteristic curve (K).
5. Process according to Claim 4, characterised in that the value of the movement command (M) to be used for the further positioning processes is determined as a null position of the adjusting member (2) from at least one of the amounts: gradient m, absolute term n correlation coefficient r and/or dispersion s².
6. Process according to one of the preceding Claims, characterised in that with the construction of the drive (4) fitted to the adjusting member (2) as a stepping motor, the movement commands (M) are fed in the form of step values.
7. Device for carrying out the process according one of Claims 1 to 6 wherein the adjusting member (2) is movable via a fitted drive (4) with respect to a stop particularly constructed as a rotatable roller (1) and the position of the adjusting member (2) can be sensed via a position sensor (5), past which the adjusting member (2) can be positioned by the provision of movement commands (M) and in addition to this a null position in which the adjustment member (2) lies against stop (1) can be determined from a characteristic curve (K) defined by the movement commands (M) and the position sensor signals (S), characterised in that by means of the motor control (5) during the process, the adjusting member (2) is' moved in the direction of stop (1) to at least one point (P) which can be determined by the movement commands (M) and the position sensor signals (F) defining a characteristic curve (K), an auxiliary characteristic curve (HK) in the form of a straight line can be determined, the gradient of which is less than the value of the gradient of the characteristic curve (K) at point (P1) and as null position value a value of the movement commands (M) is used at which the position sensor difference value (Δs) between characteristic curve (K) and auxiliary characteristic curve (EK) takes up the maximum value.
8. Device according to Claim 7, characterised in that via the motor control (5), the value of the movement command (M) to be used for the further positioning processes as the null position of the control member (2) can be determined from a comparison of values of the position sensor signal (S) of at least one auxiliary characteristic curve (HK) with the corresponding values of the characteristic curve (K).
9. Device according to Claim 8, characterised in that by means of the motor control (5) at at least one point of the characteristic curve (K) an auxiliary characteristic curve (HK) can be determined in the form of a straight line with differing gradient.
10. Device according to one of Claims 7-9, characterised in that via the motor control (5), the value of the movement command (M) to be used for the further positioning processes as a null position of the adjusting member (2) can be determined by means of regression lines definable by points on the characteristic curve (K).
11. Device according to Claim 10, characterised in that by means of the motor control (5), the value of the movement command (M) to be used for the further positioning processes can be determined as the null position of the adjusting member (2) from at least one of the dimensions: gradient m, absolute term n, correlation coefficient r and/or dispersion s².
12. Device according to one of Claims 7-11, characterised in that the drive (4) of the adjusting member (2) is constructed as a stepping motor to which movement commands (M) can be fed in the form of step values by the motor control (5).

Images