DE102022108716A1 - Process for dusting printed sheets with powder - Google Patents

Abstract

In a method for dusting printed sheets (3) with powder (5), at least one actual value of at least one parameter of the powder (5) is measured. The actual value is measured in a measuring chamber (10) between a storage chamber (7) and a dosing chamber (11) for the powder (5). A computer carries out a target/actual comparison with a target value and an evaluation for each parameter.

Description

The present invention relates to a method for dusting printed sheets with powder, with at least one actual value of at least one parameter of the powder being measured.

In DE 38 19 203 A1 a pollination device is described with which such a method can be carried out. However, a sufficiently high process stability is not achieved with this pollination device.

The object of the invention is to specify a method for dusting printed sheets with powder, in which a sufficiently high level of process stability is ensured.

The object is achieved by a method for dusting printed sheets with powder, with at least one actual value of at least one parameter of the powder being measured, characterized in that the actual value is measured in a measuring chamber between a storage chamber and a dosing chamber for the powder and that a target/actual comparison with a target value and an evaluation are carried out by a computer for each parameter.

One advantage of the method according to the invention is that batch-to-batch fluctuations in the properties of the powder can be recognized in good time and a response can be made to them.

In a further development, the parameter or parameters is or are the flowability and/or moisture content and/or grain size and/or grain size distribution and/or temperature of the powder.

The measurement can be carried out on powder trickling in free fall in the measuring chamber.

The target value or values can be determined empirically.

Each target value can be determined by the self-learning computer from processed OK orders.

For example, the operator can enter into the computer which print jobs have been processed with particularly good quality. Based on these print jobs, the computer calculates the target value.

Depending on each target/actual comparison, the computer can issue a recommendation for the parameter setting.

An evaluation unit having the measuring chamber and the computer can be permanently active.

However, for certain applications it can also be provided that the evaluation unit having the measuring chamber and the computer is only temporarily active.

• 1 eine Druckmaschine in Gesamtansicht,
• 2 eine Bestäubungsvorrichtung der Druckmaschine als Einzelheit und
• 3 eine Auswerteinheit mit einer Messkammer.

Further developments result from the following description of an exemplary embodiment and the associated drawing, which shows:

• 1 a printing machine in general view,
• 2 a dusting device of the printing machine as a detail and
• 3 an evaluation unit with a measuring chamber.

1 shows a printing press 1 with a delivery 2, in which printed sheets 3 are laid out on a stack 4. A dusting device 6 is arranged in the boom 2 for dusting the printed sheets 3 with powder 5 .

2 shows that the dusting device 6 has a storage chamber 7 for the powder 5, which has an outlet 8 with a flap 9 at the lower end. Below the storage chamber 7 is a measuring chamber 10 into which the powder trickles through the outlet 8 from the storage chamber 7 in free fall. A dosing chamber 11 into which the powder 5 from the measuring chamber 10 reaches is arranged below the measuring chamber 10 . At the lower end of the dosing chamber 11 there is an outlet 12 with a dosing roller 13 whose rotational speed determines the amount of powder 5 which per unit time passes from the dosing chamber 11 through the outlet 12 into a line system 14 .

A mixing chamber 15 is integrated into the line system 14 , in which the powder 5 from the dosing chamber 11 is mixed with compressed air 16 from an air connection 17 in order to form a powder/air mixture 18 . The powder-air mixture 18 passes via the line system 14 into a distributor 19 in which it is distributed to nozzles 20 of a powder stick 21 . The nozzles 20 eject the powder/air mixture 18 onto the printed sheet 3 running past.

3 shows a schematic of an evaluation unit 22 which has a computer 23 . A camera 24 is arranged in the measuring chamber 10 and is aimed at a trickling jet 25 formed by the powder 5 trickling from the flap 9 . The flap 9 is made to vibrate by a vibrator 26 in order to support the formation of the trickle jet 25 . The camera 24 is connected to the computer 23 and is used for The computer 23 determines the grain size, the grain size distribution and the flowability of the powder 5 . A moisture sensor 27 and a temperature sensor 28 are integrated into the flap 9 . The humidity sensor 27 measures the humidity of the powder 5 on the flap 9 and the temperature sensor 28 the temperature of the powder 5 on the flap 9.

The two sensors 27, 28 signal their measured values to the computer 23 to which they are connected. The computer 23 compares the measured actual value with a target value stored in the computer 23 for each parameter (humidity, temperature, grain size, grain size distribution and flowability of the powder). The respective target value can be determined empirically, z. B. by the computer 23 self-learning from in the printing press 1 already processed OK jobs.

The computer 23 is connected to a control station (not shown in the drawing) of the printing press 1 and, depending on the result of the respective target/actual comparison, signals a recommendation 29 for setting the respective parameter. The operator can read the respective recommendation 29 on the control station and set the parameters accordingly, e.g. B. by loading the dusting device 6 with a different type of powder. The result of the respective target/actual comparison represented by recommendation 29 can be shown to the operator at the control station, e.g. B. in the form of a "traffic light". Green means that the parameter setting is optimal, yellow means that this setting is acceptable, and red means that the parameter setting should be corrected.

The evaluation unit 22 can work continuously or discontinuously, e.g. B. periodically or only for a certain period of time at the beginning of the processing of each print job. With continuous operation, not only batch fluctuations in the properties of the powder 5 but also changes in the properties of the powder 5 over time can be detected and corrected.

Reference List

1

printing press

2

boom

3

press sheet

4

stack

5

powder

6

pollination device

7

pantry

8th

outlet

9

flap

10

measuring chamber

11

dosing chamber

12

outlet

13

dosing roller

14

piping system

15

mixing chamber

16

compressed air

17

air connection

18

powder-air mixture

19

distributor

20

jet

21

powder stick

22

evaluation unit

23

calculator

24

camera

25

trickle jet

26

shaker

27

humidity sensor

28

temperature sensor

QUOTES INCLUDED IN DESCRIPTION

This list of the documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• DE 3819203 A1 [0002]

Claims (8)

Method for dusting printed sheets (3) with powder (5), with at least one actual value of at least one parameter of the powder (5) being measured, characterized in that the actual value is measured in a measuring chamber (10) between a storage chamber (7 ) and a dosing chamber (11) for the powder (5) and that a computer (23) carries out a target/actual comparison with a target value and an evaluation for each parameter. procedure after claim 1 , characterized in that the parameter or parameters is or are the flowability, moisture, grain size, grain size distribution and/or temperature of the powder (5). procedure after claim 1 or 2 , characterized in that in the measuring chamber (10) the powder (5) trickles during the measurement. Procedure according to one of Claims 1 until 4 , characterized in that each target value is determined empirically. procedure after claim 4 , characterized in that the computer (23) uses self-learning to determine each target value from processed OK orders. Procedure according to one of Claims 1 until 5 , characterized in that a recommendation (29) for parameter setting is issued by the computer (23) as a function of each target/actual comparison. Procedure according to one of Claims 1 until 6 , characterized in that an evaluation unit (22) having the measuring chamber (10) and the computer (23) is permanently active. Procedure according to one of Claims 1 until 6 , characterized in that an evaluation unit (22) having the measuring chamber (10) and the computer (23) is temporarily active.

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