阅读说明：本技术 经改善的页张行进监控 (Improved sheet travel monitoring ) 是由 S·克瑙夫 H·布克 J·里茨 V·希默尔斯巴赫 M·雅诺恰 J·舒尔特 T·佩斯勒 于 2020-11-12 设计创作，主要内容包括：本发明涉及一种用于在页张印刷机中以计算机支持的方式进行页张行进监控的方法,其中,在印刷运行中测量传感器(1a、1b)检测在印刷机中的页张(7)且激活传感器(2)通过激活信号(20)触发测量传感器(1a、1b)的测量,其特征在于,激活传感器(2)机械式固定地安装而无需校正,且确定和补偿激活信号(20)的时间偏差。(The invention relates to a method for computer-assisted monitoring of the advance of sheets in a sheet-fed printing press, wherein during a printing operation a measuring sensor (1a, 1b) detects a sheet (7) in the printing press and an activation sensor (2) triggers a measurement of the measuring sensor (1a, 1b) by means of an activation signal (20), characterized in that the activation sensor (2) is mounted mechanically fixed without correction and in that the time offset of the activation signal (20) is determined and compensated.)

1. A method for monitoring the advance of a sheet in a sheet-fed printing press in a computer-assisted manner,

wherein, in a printing operation, a measuring sensor (1a, 1b) detects a printing sheet (7) in the printing press and

the activation sensor (2) triggers a measurement of the measurement sensor (1a, 1b) by means of an activation signal (20),

it is characterized in that the preparation method is characterized in that,

the activation sensor (2) is mounted mechanically fixed without correction, and

-determining and compensating for a time deviation of the activation signal (20).

2. The method of claim 1, wherein the first and second light sources are selected from the group consisting of,

it is characterized in that the preparation method is characterized in that,

a time deviation of the activation signal (20) is determined by scaling the duration of the activation signal (20) at a constant speed of the sheet-fed printing press by a factor.

3. The method of claim 2, wherein the first and second light sources are selected from the group consisting of,

it is characterized in that the preparation method is characterized in that,

a computer (21) detects a duration of the activation signal (20) at a constant speed of the sheet printing press during a learning process in the constant speed of the sheet printing press, which learning process is carried out separately from a regular printing run of the sheet printing press.

4. The method of claim 3, wherein the first and second light sources are selected from the group consisting of,

it is characterized in that the preparation method is characterized in that,

a computer (21) determines the current speed of the sheet-fed printing press during a printing operation of the sheet-fed printing press by forming a proportional relationship between the detected duration of the activation signal (20) at a constant speed during a learning process and the measured duration of the activation signal (20) during the printing operation.

5. The method of claim 4, wherein the first and second light sources are selected from the group consisting of,

it is characterized in that the preparation method is characterized in that,

the coefficient is calculated by determining a ratio of a current speed of the sheet printing press in a printing operation to a constant speed of the sheet printing press in a learning process.

6. The method of claim 5, wherein the first and second light sources are selected from the group consisting of,

it is characterized in that the preparation method is characterized in that,

the measuring sensors (1a, 1b) serve as a computer (21), and

the measurement sensor determines and stores the detected duration of the activation signal (20) at a constant speed during a learning process and the measured duration of the activation signal (20) during a printing run.

7. The method of claim 6, wherein the first and second light sources are selected from the group consisting of,

it is characterized in that the preparation method is characterized in that,

the calculation of the coefficients by the measuring sensors (1a, 1b) is carried out by means of the following variables:

-a stored duration of the activation signal (20) at a constant speed in a learning process,

-the measured duration of the activation signal (20) in a printing run, and

-a constant speed of the sheet printing press during the learning process.

8. The method according to one of claims 2 to 7,

it is characterized in that the preparation method is characterized in that,

the duration of the activation signal (20) is determined by detecting the time during which the activation sensor (2) is in an activated or deactivated state during the sheet travel.

9. The method according to one of claims 2 to 8,

it is characterized in that the preparation method is characterized in that,

the constant speed of the sheet-fed printing press is so low that the sampling rate of the sensors (1a, 1b, 2) and the electronic processing time thereof do not influence the determination of the time offset of the activation signal (20).

10. A system for computer-assisted monitoring of sheet travel in a sheet-fed printing press, comprising a mechanically fixedly mounted activation sensor (2) and a measuring sensor (1a, 1b) as a computer (21),

wherein the system operates in accordance with the method of one of the preceding claims.

Technical Field

The invention relates to a method for improved monitoring of sheet travel (Bogenlaufkontrolle) in a sheet printing press by means of a mechanically fixedly mounted activation sensor (Aktivierungssensor).

The invention belongs to the technical field of page conveying of a printing machine.

Background

The monitoring of the sheet travel of the sheet printing press has the following functions: the sheet loss in the printing unit or between several printing units is detected in order to avoid contamination of the machine or, in the extreme case, damage to the machine due to the impression of the respective printing cylinder. For this purpose, systems are used today which are composed of two types of sensors: including detecting an overrun of the sheet in the gripperAnd also includes an activation sensor. Such an activation sensor triggers a measurement of the sheet travel sensor at a specific angle in that it recognizes a rotating identifier (Fahne) on the cylinder and can itself be moved in the circumferential direction for calibration purposes. The angle determined must naturally be calibrated with a certain tolerance for the correct function of the sheet advance sensor. This takes place in that the activation sensor is moved in the circumferential direction.

The sheet advance sensor is either embodied as an optical measuring sensor, which detects an object in the detection area, or as an ultrasonic measuring sensor, which detects a reflector mounted on the drum (as long as the reflector is not covered by the sheet). In case of activated sensor miscalibration: or the measuring sensor occasionally does not recognize the object and stops the machine (despite the presence of the sheet), in which case this calibration may be set to be too early in time; or the measuring sensor always recognizes the cylinder (although no sheet is present), in which case the calibration may be set too late. In the latter case, the monitoring function is no longer ensured at all.

The correct calibration of the activation sensor is naturally a time-consuming and error-prone process (during assembly and during maintenance). The activation is performed by a machine controller, which requires a vibration model of the machine and is therefore very complex. The behavior of the machine vibrations is dependent on a plurality of parameters for which a functional relationship must be simulated or measured. These parameters include: such as the temperature of the machine, the load, the operating state, the machine configuration, possibly also the properties of the printing ink, the properties of the lubrication, the position of the main drive, etc. It is therefore advantageous to reduce this cost.

For the mechanical calibration of the activation sensor, auxiliary and operating means are therefore provided in the assembly in order to simplify the work. If possible, this calibration is carried out during assembly on the individual printing couples, wherein the sensors and the holders are well accessible during calibration. This is naturally not possible during maintenance.

In this connection, a method is also described in german patent application DE 102017220039B 3, which makes it possible to dispense with such an activation sensor and to carry out the activation by means of a torsion model by means of a machine controller. Due to the torsion of the machine and due to the dependency of several parameters (e.g. machine load, whether the machine is operating under pressure, temperature, etc.) on one another, the determination of the machine torsion model parameters is likewise very complex and must be carried out individually in the worst case on the basis of tolerances for each machine sample.

Disclosure of Invention

The object of the present invention is therefore to provide a method for improved monitoring of the advance of sheets in a sheet-fed printing press, which is more accurate and less susceptible to disturbances than the methods known from the prior art.

The object is achieved by a method for computer-assisted monitoring of the advance of sheets in a sheet-fed printing press, wherein, during a printing operation, a measuring sensor detects a sheet in the printing press and an activation sensor triggers a measurement of the measuring sensor by means of an activation signal, characterized in that the activation sensor is mounted mechanically fixed without correction (ohne job) and a temporal deviation of the activation signal is determined and compensated. The most important points of the method according to the invention are: the activation sensors no longer need to be recalibrated to achieve accurate actuation of the measurement sensors, but are rather mounted mechanically fixed in the printing press. This eliminates the need for extremely sensitive and partially inaccurate calibration of the activation sensors, and, in addition to avoiding a possible source of error, reduces the corresponding time required for correction. By fixing the active sensor, the latter naturally no longer detects the incoming sheet at the desired point in time, which results in a delayed or early actuation of the measuring sensor. In order to compensate for this and to actuate the measuring sensor at the correct time, a deviation in time of the activation signal triggered by the activation sensor must therefore be determined. Thus, if the deviation of the activation signal is known, the measurement of the measuring sensor can be adapted without problems with reference to the determined deviation. The activation sensor is positioned and fixed during installation in such a way that its activation signal is always output earlier.

Advantageous, and therefore preferred, developments of the invention result from the dependent claims and the description and the accompanying drawings.

A preferred development of the method according to the invention consists in determining the deviation of the activation signal in time by scaling (masking) the duration of the activation signal at a constant speed of the sheet-fed printing press by a factor (Faktor). It is therefore important for the calculation of the deviation of the activation signal in time to measure the duration of the activation signal at a constant speed of the sheet-fed printing press and to scale it by the calculated compensation factor in such a way that the time deviation of the activation signal is taken into account for the duration of the activation signal accordingly.

In a further preferred development of the method according to the invention, the computer detects the duration of the activation signal at the constant speed of the sheet printing press during a separate learning process (Lernlauf) at the constant speed of the sheet printing press in relation to the regular printing operation of the sheet printing press. This is necessary because the sheet-fed printing press naturally does not always print at a certain constant speed during its normal printing operation. The calculation to be performed for the time offset of the activation signal however requires that the duration of the activation signal is detected with a known and thus constant speed, in order to be able to perform scaling with these known values for taking into account the time offset.

In a further preferred development of the method according to the invention, the computer determines the current speed of the sheet-fed printing press during a printing operation of the sheet-fed printing press by forming a ratio between the detected duration of the activation signal at a constant speed during the learning process and the measured duration of the activation signal during the printing operation. The determination of the time offset of the activation signal therefore requires that the respective current speed of the sheet-fed printing press be determined during the printing operation. This is calculated by forming a proportional relationship between the detected duration of the activation signal at constant speed in the respective learning process and the measured duration of the activation signal in the printing run as a variableThe time offset of the activation signal can then be determined based on the current speed of the sheet-fed printing press in the printing operation.

In a further preferred development of the method according to the invention, the coefficient is calculated by determining a proportional relationship between a current speed of the sheet-fed printing press in a printing mode and a constant speed of the sheet-fed printing press in a learning mode. As mentioned above, the determination of the time order of the activation signals takes place by means of coefficient scaling. The coefficient is determined by determining a proportional relationship between the current speed of the sheet-fed printing press determined during the printing operation and the constant speed known during the learning process. With the calculated coefficients, the duration of the activation signal during the learning process (i.e. at a constant speed of the printing press) can then be scaled to a value during the printing run that takes into account the corresponding time offset of the activation signal, which is caused by the mechanically fixedly mounted activation sensor.

A further preferred development of the method according to the invention consists in using a measuring sensor as a computer and in ascertaining and storing the detected duration of the activation signal at constant speed during the learning process and the measured duration of the activation signal during the printing operation. Since the measuring sensor has its own control system (usually in the form of a microcontroller or the like), this control system can accordingly be used to determine the duration of the activation signal at constant speed during the learning process and to measure the duration of the activation signal during the printing run, in order to form the above-mentioned proportional relationship (or coefficient) of the control system of the measuring sensor. The control system of the measuring sensor is then embodied as a computer which likewise directly carries out a corresponding scaling of the coefficients for taking into account the time offset. Alternatively, the determination and compensation of the time offset of the activation signal can naturally also be carried out by an external computer, which then informs the measurement sensor of the calculated time offset (or controls it with a corresponding delay). However, it is still easier and more efficient to perform by the measurement sensor itself.

In a further preferred development of the method according to the invention, the calculation of the coefficients by the measuring sensor is carried out with the aid of the stored duration of the activation signal at constant speed in the learning process, the measured duration of the activation signal in the printing operation, and the constant speed of the sheet-fed printing press in the learning process. If the detection of the duration of the activation signal during the learning process and during the printing operation, respectively, is carried out by the measuring sensor and stored, the calculation carried out by the coefficients for taking into account the time offset is also carried out logically in the measuring sensor.

A further preferred development of the method according to the invention provides that the duration of the activation signal is determined by detecting the time during which the activation sensor is in the active or inactive state during the sheet advance. The direct detection of the activation phase of the activation sensor has the following advantages in this case: fluctuations in the machine speed during the measurement during the printing run do not adversely affect the measurement result. Indirect detection by determining the inactive phase of the activation signal has the following advantages: the electronic processing time and the running time of the sensor (resulting from the sampling rate) hardly have an adverse effect, since a longer period of time is measured (relative to the duration of the activation signal).

A further preferred development of the method according to the invention consists in that the constant speed of the sheet-fed printing press is so low that the sampling rate (abstract) of the sensor and its electronic processing time do not influence the determination of the time offset of the activation signal. In principle, naturally, every machine speed can be used as a constant speed in the learning process. At very high machine speeds, however, the electronic processing time and the operating time of the sensors (resulting from the sampling rate) are also affected, since the electronic processing time and the operating time of the sensors become more important when the speed of the sheet-fed printing press is correspondingly high and when the duration of the activation signal is correspondingly short, which in turn adversely affects the determination of the time offset as a disturbance variable. It is therefore preferable for the learning process to be as low as possible at a constant speed.

The method according to the invention is also carried out on a system for monitoring the advance of sheets in a sheet-fed printing press, comprising a computer, an activation sensor mounted in a mechanically fixed manner, and a measurement sensor.

Drawings

The invention itself, as well as advantageous constructional and functional improvements of the invention, are further described in the following in accordance with at least one preferred embodiment with reference to the accompanying drawings. In the drawings, elements that correspond to one another are provided with the same respective reference numerals.

The figures show:

FIG. 1: a system consisting of a prior art sheet travel sensor and an activation sensor;

FIG. 2: activating a faulty calibration of the sensor in the prior art system;

FIG. 3: calculating the running time of the ultrasonic wave;

FIG. 4: an activation sensor fixedly installed according to the invention;

FIG. 5: a rectangular signal generated by the activation sensor at the switch output (Schaltausgang);

FIG. 6: ideal measurement points after the falling side of the signal (Flanke);

FIG. 7: maintenance of the ultrasound runtime (Vorhaltung).

Detailed Description

As in the prior art, a system of an activation sensor 2 and sheet travel measurement sensors 1a, 1b is used, which is controlled by a computer. Here, a system consisting of two sensors is used, which comprises: the sheet advance sensors 1a, 1b (hereinafter referred to as measuring sensors only) which detect the excess of the sheet 7 in the gripper, as well as the activation sensor 2 and the reflector 6 in the drum, on which reflector 6 an optical or ultrasonic signal is reflected for measurement. Such a system is shown in fig. 1, specifically for measuring 4 without sheet, wherein the corresponding reflected signal in turn indicates that no sheet 7 is present. Fig. 1, on the other hand, shows a measurement 3 with a sheet, in which the signal is scattered by the sheet, so that this measurement indicates the presence of a printed sheet 7. However, for the system to function correctly, it is necessary to set the activation sensor 2 absolutely correctly (Einstellung). For this purpose, the correct measurement angle α is shown₀5. As a computer, the measuring sensors 1a, 1b (or their control systems) are preferably used directly. Alternatively, however, an external computer 21 can also be used, which external computer 21 then informs the above-mentioned measuring sensors 1a, 1b of the necessary data.

In the event of a faulty calibration of the active sensor 2, the measuring sensors 1a, 1b (either implemented as optical measuring sensor 1a or as super-calibrated)Acoustic wave measuring sensor 1b) either occasionally recognizes the absence of object 7 and stops the printing press (despite the presence of sheet 7) or always recognizes the cylinder and therefore assumes that sheet 7 is detected (despite the absence of sheet 7). In the first case, the calibration takes place in such a way that the measurement takes place prematurely at a measurement angle α that is too small_f10 carry out 8, in the second case, the measurement takes place too late at an excessively large measurement angle α_s11 execution 9 so that the reflector 6 is missed. These two cases are shown in two-part figure 2: the premature calibration 8 is on the left and the late calibration 9 is on the right.

In the method according to the invention, the activation sensor 2 is fixedly installed in the printing press, so that, in the event of any occurring tolerances, the target 15 (e.g. the incoming sheet 7) activates the activation sensor 2 before the ideal measurement time 16. Fig. 4 shows an example of such a fixedly mounted activation sensor 2, where α_EinAngle of entry of object, α_AusIs the angle of departure of the target. The activation sensor 2 then generates a rectangular signal 20 at the switch output: if the target 15 is identified, it is HIGH 18, otherwise LOW 17. Such a rectangular signal 20 is shown in fig. 5, where T_EinTime of target entry, T_AusThe time of departure of the target. Due to the early activation, a constant angular difference Δ α exists between the ideal measurement point in time 16 and the falling side of the activation signal_REF. The angular difference Δ α_REFDepending on the tolerances of the measuring sensors 1a, 1b, the sensor holder and the target 15 and generally from printing unit to printing unit.

At a known machine speed, the time difference can be calculated from the angular difference:

during the learning process, this time difference Δ T is determined at the lowest possible machine speed_REF. The machine speed should be slow, whereby the sampling rate and the electronic processing time of the measuring sensors 1a, 1b appear to be comparable to the machine speedIs of less importance. Fig. 3 shows an example for calculating the ultrasonic operating time of the measuring sensor 1b, to which the sampling rate of the measuring sensor 1b is related. In the learning process, the following are also determined in the measuring sensors 1a, 1 b: at the machine speed for a time period Δ T_TARGETHow large is, during which time period Δ T_TARGETThe activation sensor recognizes the target 15. These durations Δ T_TARGETAnd Δ T_REFPermanently stored in the measuring sensor 1a, 1 b.

Both of these time periods scale inversely proportional to machine speed, i.e.: the machine speed is varied by a factor r and the time period is varied by(ii) a change; in the case of double machine speed, the time period is halved. In this way, the machine speed and the ideal measurement time 16 can be calculated in the measuring sensors 1a, 1b, i.e.: independently of the machine speed, the measuring sensors 1a, 1b can trigger measurements at the desired moment. For this purpose, the measuring sensors 1a, 1b measure the length Δ T of the signal generated by the target 15_TARGET,ω1. The current machine speed can thus be determined by forming a proportional relationship between the stored pulse width and the measured pulse width at the reference speed. After the falling side of the signal 20, it has to be waited until the duration of the ideal measurement instant 16 is reached to trigger the measurement. This duration corresponds to the duration stored for the reference speed, which is scaled based on the proportional relationship between the current machine speed and the reference speed. The fact situation is shown by the following formula:

thus, FIG. 6 shows signal 20 having a falling side followed by itOff ideal measurement instant 16, where T_EinTime of target entry, T_AusThe time of departure of the target.

In an alternative embodiment, the calculation in the measuring sensors 1a, 1b can also be carried out using characteristic curves, i.e.: for the measuring sensors 1a, 1b, the relationship between the length of the activation pulse at initialization and the ideal time of measurement is transmitted by the controller in the form of a characteristic curve with a control point (St ü tzstellen). If the measuring sensors 1a, 1b measure the activation pulses between two control points, a linear interpolation is correspondingly used.

In another embodiment, it is also possible to inform the measuring sensors 1a, 1b of the machine speed by means of a printing press controller in the form of a computer 21, instead of calculating the machine speed in the measuring sensors 1a, 1b by means of a pulse width measurement. This naturally has the disadvantage: there is additional communication between the measuring sensors 1a, 1b and the computer 21. Furthermore, the machine speed may change rapidly (for example in the case of an emergency stop), so that the speed must be notified frequently, or a deviation between the notified speed and the real speed is generated. In a preferred embodiment, the pulse width Δ T is measured by measuring the pulse width just before the measurement_TARGETTo determine the machine speed so that over a time period deltat_REF,ω1During which the machine speed variations can be ignored.

Furthermore, in a further alternative embodiment, it is also possible, instead of the length of the pulse (i.e. the duration of the presence of the HIGH signal 18), to measure the length of the LOW signal 17 and thus calculate the machine speed. However, because the HIGH signal 18 is present for a much shorter time (i.e., only about 1% of the time), the measurement of the HIGH level is naturally less affected by variations in machine speed.

The advantages of the method according to the invention over the prior art can be summarized as follows:

1. the elimination of calibration improves the stability and the availability of the monitoring, and reduces the effort during assembly and during maintenance.

2. Activation pulses shorter than the lower limit or longer than the upper limit are rejected. In this case no measurement is triggered. Such an inactive duration of the activation pulse can indicate that an emc interference or malfunction of the activation sensor has occurred.

3. The ultrasonic runtime is maintained as shown in fig. 3. In the prior art, the sheet travel monitoring is calibrated when the printing press is stopped.

Thus, in the case of the ultrasonic measurement sensor 1b, an error is generated by ignoring the operation time of the ultrasonic packet (ultrashallpaket), and the error becomes larger as the machine speed becomes larger. Since the propagation speed of the ultrasound package is much smaller than the light propagation speed of the optical measurement sensor 1 a. In this case, at high machine speeds, the reflector 6 is still in the correct position at the time 12 when the ultrasonic measuring sensor 1b is activated, whereas the drum has rotated further when the ultrasonic packet reaches 13 the reflector 6, which leads to an excessively large measuring angle α_R14. In contrast, in the method according to the invention, the ultrasound transit time already comprises the duration Δ T determined in the learning process_REFIn (1). This results in a dead time (Totzeit) which is constant over a time period Δ T_USAre not scaled together but must be preserved at every machine speed, i.e.: the measurement-correct trigger 19 must always be Δ T compared to the situation in which the printing press reaches the ideal measurement instant 16 ignoring the above-mentioned running time_USOccurs earlier. This is correspondingly illustrated in fig. 7, where T_EinTime of target entry, T_AusTime of departure, Δ T_GESAMT,ω1Is the total time as shown. The ultrasonic runtime is known on the basis of the distance between the measuring sensor and the ultrasonic reflector 6. The fact situation is depicted by the following formula:

list of reference numerals:

1a optical sheet advance sensor

1b ultrasonic sheet advance sensor

2 activating the sensor

3 measuring with sheets

4 measurement of no page

5 measuring the angle alpha₀

6 reflector

7 printing sheet

8 measure prematurely

9 measure too late

Measurement angle α of 10 too small_f

11 excessive measurement angle alpha_s

12 moment of activation

13 time of arrival of ultrasound package

14 measurement angle α too large_R

15 target

16 ideal measuring time

17 LOW-no target identified

18 HIGH-recognition of target

19 triggering of measurement

20 rectangle signal/activation signal

21 computer