Method for controlling a sheet feeder

Abstract

The invention relates to a method for controlling a sheet feeder, wherein a suction head (1) is adjusted according to the measured values ​​of a sensor. A suction head strip (6) having sheet processing elements of different types is automatically adjusted relative to the suction head (1).

Description

Technical Field

[0001] The invention relates to a method for controlling a sheet feeder, wherein a suction head is adjusted as a function of measured values ​​of a sensor. Background Art

[0002] One such method is described in WO 2022 / 058058 A1. Summary of the invention

[0003] The object of the present invention is to specify a further method for controlling a sheet feeder.

[0004] This object is achieved by a method for controlling a sheet feeder, in which a suction head is displaced / adjusted (verstellt) as a function of the measured values ​​of a sensor, characterized in that a suction head strip with sheet processing elements of different types is automatically adjusted relative to the suction head in order to set the suction head strip together with the sheet processing elements fastened thereto to the desired position relative to the rear edge of the stack.

[0005] One advantage is that manual calibration by the operator is no longer required.

[0006] An additional advantage is that operational reliability is increased and incorrect and duplicated sheets are avoided.

[0007] The following improvements are possible in any combination:

[0008] The tip strip may be adjusted based on the measurements of the sensor.

[0009] The sensor may be used at each sheet transfer or at each sheet transfer cycle (pro ) performs measurements for determining the position of the trailing edge of a sheet and measurements for determining the position of the trailing edge of a stack.

[0010] The different types of sheet processing elements can include a blower and / or a stop and / or a wiper as element types.

[0011] The sensor may be a profile sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Improvements can also be seen from the following description of the embodiments and the accompanying drawings, which show:

[0013] Figure 1 : Top view of the suction head;

[0014] Figure 2 and Figure 3 : Side view of the tip; and

[0015] Figure 4: Schematic diagram of the coupled regulation loop. DETAILED DESCRIPTION

[0016] Figure 1 A feeder (e.g. of a printing press) is shown in a partial view. The partial view shows a suction head 1 which has a lifting suction device 2, a drag suction device 3, an inner scraper spring 4 and a probe 5. In addition, a suction head strip 6 is fastened to the suction head 1. The probe 5 detects the height of the stack 7. The lifting suction device 2 lifts the sheets 8 successively from the stack 7. The drag suction device 3 conveys the sheets 8 in a direction 9. The inner scraper spring 4 holds the sheets 8 on the stack 7.

[0017] The suction head strip 6 carries different types of sheet handling elements: a rear edge stop 10, a rear edge blower 11, a loosening blower 12, a carrying blower 13, an ion blower 14 and an outer scraper spring 15. The rear edge stop 10 supports the upper sheet 8 in the stack 7 on the rear edge of the sheet. The rear edge blower 11 blows air between the rear edges of the upper sheets 8 in the stack 7 at the corners of the stack. The loosening blower 12 blows air between the upper sheets 8 in the stack 7 near the center of the stack width to loosen them. The carrying blower 13 blows air between the stack 7 and the sheet 8 held by the lifting suction device 2, which carries the sheet 8 and assists in completely separating the sheet 8 from the stack 7.

[0018] The ion blowers 14 are optional and are only used when processing sheets 8 made of foil / film. These ion blowers 14 blow ionized air between the film sheets to suppress the problem of static adhesion of the film sheets to each other. These ion blowers 14 can be turned off when processing paper and can be omitted in machines that do not process film sheets. The outer scraper spring 15 (like the inner scraper spring 4) prevents the lifting suction device 2 from lifting more than one sheet 8 from the stack 7.

[0019] The suction head strip 6 is supported in the suction head 1 in such a way that it can be adjusted in and against the direction 9, as indicated by the arrow 16. The suction head strip 6 and the sheet processing elements carried by it (external wiper, stop, blowers 11 to 14) are adjusted together with respect to the suction head 1 and the sheet processing elements arranged on it (suction devices 2, 3, internal wiper, probe 5).

[0020] Figure 2 and Figure 3It is shown that a contour sensor 17, in particular a 2D contour sensor, is arranged, which scans a measuring region 19 with its laser beam 18, which detects a stack rear edge 20 of the stack 7 and a sheet rear edge 21 of a sheet 8 held by the lifting suction device 2. The measuring region 19 extends as a horizontal line on the upper side of the stack 7 in the direction 9 and as a vertical line on the rear side of the stack 7. The contour sensor 17, like the probe 5, is arranged in the center of the stack width.

[0021] The profile sensor 17 performs two measurements during each sheet transport cycle or each machine revolution (revolution of the plate cylinder of the printing press):

[0022] Figure 2 One such measurement is shown, in which the profile sensor 17 locally measures the height profile 43 of the stack 7. This measurement is carried out after the drag suction device 3 has conveyed the previously separated sheet 8 out of the field of view (measuring region 19) of the profile sensor 17 and before the lift suction device 2 removes the next sheet 8 to be separated from the stack 7. The associated software of the profile sensor 17 evaluates the measured height profile in real time and outputs a measured value 25 for the measurable position of the stack rear edge 20 in the direction 9 (see Figure 4 ).

[0023] Figure 3 Another measurement is shown, in which the profile sensor 17 locally measures the height profile of a sheet 8 held by the lifting suction device 2. This measurement is carried out after the lifting suction device 2 has removed the sheet 8 from the stack 7 and before the drag suction device 3 has transported the sheet 8 away from the stack 7 in the direction 9. The associated software of the profile sensor 17 evaluates the measured height profile in real time and outputs a measured value 26 for the measurable position of the rear edge 21 of the lifted sheet 8 in the direction 9 (see Figure 4 ). This position actually corresponds to the position of the rear edge of the sheet 8 which is located at the top of the stack 7.

[0024] Figure 4 A first control circuit 22 is shown for automatically calibrating or tracking the position of the suction head 1 including the suction head strip 6 supported therein along and against the direction 9 in order to set the suction head 1 to a desired position relative to the rear edge of the uppermost sheet 8 in the stack 7 .

[0025] Figure 4 Also shown is a second control circuit 23 for automatically calibrating or tracking the position of the suction head strip 6 relative to the suction head 1 along and against the direction 9 in order to set the suction head strip 6 (or the sheet handling element fastened thereto) to a desired position relative to the rear edge 20 of the stack.

[0026] The dashed line shows the control coupling 24 of the first control loop 22 to the second control loop 23. This coupling 24 allows the second control loop 23 to take into account (or compensate for) the adjustment of the nozzle head 1 together with the nozzle strip 6 relative to the machine frame caused by the first control loop 22 when adjusting the nozzle head strip 6 relative to the nozzle head 1.

[0027] The two control loops 22 , 23 include the same contour sensor 17 and function as follows:

[0028] In the first control loop 22, the contour sensor 17 implements a reference Figure 3 The measurement described. The corresponding n (number) most recently measured measured values ​​26 are digitally stored in a memory 27 of the electronic control unit. The control unit comprises a median and / or mean value filter, by means of which the control unit calculates the median and / or mean value 28 of the n most recently measured positions of the rear edge of the sheet from the stored measured values ​​26. In this way, the influence of abnormal values ​​and measurement errors on the reliability of the system is reduced. If there are fewer than n measured values ​​26 (for example, when the machine is started), the median and / or mean value 28 is formed only by the current measured values ​​26. The difference formed by the median and / or mean value 28 and the absolute position 29 of the suction head determines the actual position 30 of the suction head relative to the rear edge 21 of the sheet. The actual position 30 of the suction head relative to the rear edge 21 of the sheet and the nominal position 31 of the suction head, which is usually zero, form the adjustment difference 32 of the regulator 33, which controls the servo drive 34, which adjusts the entire suction head 1 including the suction head strip 6 supported therein.

[0029] In the second control loop 23 , the contour sensor 17 implements a reference Figure 2 The n (number) most recently measured measured values ​​25 are stored in a memory 35 and a median or average value 36 is calculated from these measured values ​​by means of a median and / or average value filter. The advantages and the way of handling when there are fewer than n measured values ​​25 are similar to the first control loop 22. The difference between the median or average value 36 and the absolute position 37 of the tip strip determines the actual position 38 of the tip strip relative to the rear edge 20 of the stack. The actual position 38 of the tip strip relative to the rear edge 20 of the stack and the nominal position 39 of the tip strip, which is usually zero, form a control difference 40 for a controller 41, which controls a servo drive 42, which adjusts the tip strip 6 relative to the suction heads 1.

[0030] The two servo drives 34 , 42 are electric motors.

[0031] In a variant, two contour sensors are used instead of the single contour sensor 17, one of which is arranged to the right and the other to the left of the center of the stack width, as viewed in direction 9. This variant has the advantage that the nozzle strip can be adapted to the inclined rear edge of the stack.

[0032] Reference numerals list

[0033] 1 Tip

[0034] 2-stroke air intake device / lift air intake device (Hubsauger)

[0035] 3 Pulling suction device / drag suction device (Schleppsauger)

[0036] 4 Inner scraper spring

[0037] 5 Detection feeler / probe (Tastfuβ)

[0038] 6 Headlines

[0039] 7 Stack

[0040] 8 pages

[0041] 9 Direction

[0042] 10 Rear edge stop

[0043] 11 Back edge hair dryer

[0044] 12 Loose Hair Dryer

[0045] 13 Loading hair dryer

[0046] 14 Ion Hair Dryer

[0047] 15 External scraper spring

[0048] 16 Arrow

[0049] 17 Profile Sensor

[0050] 18 Laser Beam

[0051] 19 Measurement area

[0052] 20 Stacking rear edge

[0053] 21 Sheet trailing edge

[0054] 22 First regulation loop

[0055] 23 Second regulation loop

[0056] 24 Coupling

[0057] 25 Measurements

[0058] 26 Measurements

[0059] 27 Memory

[0060] 28 Average and / or median of stored values

[0061] 29 Absolute position of suction head

[0062] 30 Actual position of suction head

[0063] 31 Nominal position of suction head

[0064] 32 Adjustment error

[0065] 33 Regulator

[0066] 34 Servo Drive

[0067] 35 Memory

[0068] 36 Average and / or median of stored values

[0069] 37 Absolute position of suction head strip

[0070] 38 Actual position of suction head strip

[0071] 39 Nominal position of suction head strip

[0072] 40 Adjustment difference

[0073] 41 Regulator

[0074] 42 Servo Drive

[0075] 43 Height Profile

[0076] 44 Height Profile

Claims

1. A method for controlling a sheet feeder, wherein: Adjust the suction head (1) according to the sensor's measured value. It is characterized in that A suction head strip (6) with different types of sheet processing elements is automatically adjusted relative to the suction head (1) in order to place the suction head strip (6) together with the sheet processing elements fastened thereto in a desired position relative to the rear edge (20) of the stack.

2. The method according to claim 1, It is characterized in that The tip strip (6) is adjusted according to the measured values ​​of the sensor.

3. The method according to claim 2, It is characterized in that The sensor performs a measurement for determining the position of the rear edge (21) of the sheet and a measurement for determining the position of the rear edge (20) of the stack during each sheet transport cycle.

4. The method according to any one of claims 1 to 3, It is characterized in that The different types of sheet processing elements include blowers and / or stops and / or wipers as element types.

5. The method according to any one of claims 1 to 3, It is characterized in that The sensor is a profile sensor (17).

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