Method for sprinkling powder onto printed sheets

Abstract

The present invention relates to a method for applying powder (5) to a printed sheet (3), wherein 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 metering chamber (11) for the powder (5). A computer (23) performs a rated-actual comparison with the rated value for each parameter and performs analytical processing.

Description

Technical Field

[0001] The present invention relates to a method for applying powder to printed sheets, wherein at least one actual value of at least one parameter of the powder is measured. Background Technology

[0002] Document DE 38 19 203 A1 describes a powder-spreading device that can be used to perform a powder-spreading method. However, this powder-spreading device cannot achieve sufficiently high process stability. Summary of the Invention

[0003] The objective of this invention is to provide a method for applying powder to printed sheets, in which sufficiently high process stability is ensured.

[0004] This task is solved by a method for spreading powder onto printed sheets, wherein at least one actual value of at least one parameter of the powder is measured, characterized in that the actual value is measured in a measuring chamber between a storage chamber and a metering chamber for the powder, and the actual value is analyzed by a computer for each parameter by a rated-actual comparison (Soll-Ist-Vergleich) with a rated value.

[0005] One advantage of the method according to the invention is that it can promptly identify and respond to batch fluctuations in the characteristics of the powder.

[0006] In one extended scheme, one or more parameters are: powder flowability and / or humidity and / or particle size and / or particle size distribution and / or temperature.

[0007] The measurement can be performed on powder that falls freely in the measuring chamber.

[0008] One or more such ratings can be determined empirically.

[0009] Each rating can be learned by the computer from the completed job tasks (OK-Aufträgen).

[0010] For example, an operator can input into the computer which printing jobs have been completed with particularly good quality. The computer then calculates ratings based on these printing jobs.

[0011] The computer can output recommendations for parameter settings (Einstellung) based on each rated-actual-comparison.

[0012] This analysis and processing unit, which includes a measurement chamber and a computer, can be permanently activated.

[0013] However, for specific applications, it can also be configured such that the analysis and processing unit with the measurement cavity and computer is only temporarily activated. Attached Figure Description

[0014] An extension arises from the subsequent description of the embodiments and the accompanying drawings, wherein:

[0015] Figure 1 The printing press is shown in general view.

[0016] Figure 2 The powder-spraying device of the printing press is shown in detail, and

[0017] Figure 3 An analysis and processing unit with a measurement cavity is shown. Detailed Implementation

[0018] Figure 1 A printing press 1 is shown with a receiver 2, in which printed sheets 3 are received onto a stack 4. A powder-spreading device 6 is arranged in the receiver 2 to spread powder 5 onto the printed sheets 3.

[0019] Figure 2 As shown, the powder-spreading device 6 has a storage chamber 7 for powder 5, which has an outlet 8 with a retractable cover 9 at its lower end. A measuring chamber 10 is arranged below the storage chamber 7, into which powder 5 falls freely from the storage chamber 7 via the outlet 8. A metering chamber 11 is arranged below the measuring chamber 10, into which powder 5 flows from the measuring chamber 10 to the metering chamber 11. An outlet 12 with a metering roller 13 is located at the lower end of the metering chamber 11, and the amount of powder 5 that flows from the metering chamber 11 to the piping system 14 per unit time is determined by the rotational speed of the metering roller 13.

[0020] A mixing chamber 15 is integrated into the piping system 14, in which powder 5 from the metering chamber 11 is mixed with compressed air 16 from the air connector 17 to form a powder-air mixture 18. The powder-air mixture 18 travels through the piping system 14 to a distributor 19, where it is dispensed onto the nozzle 20 of the powder rod 21. The nozzle 20 then sprays the powder-air mixture 18 onto the passing printing sheet 3.

[0021] Figure 3The analysis and processing unit 22, including computer 23, is shown schematically. A camera 24 is arranged in the measuring chamber 10, aimed at the powder 5 scattered from the cover 9 forming a scattering bundle 25. A vibrator 26 causes the cover 9 to vibrate, facilitating the formation of the scattering bundle 25. The camera 24 is connected to the computer 23 and used to determine the particle size, particle size distribution, and flowability of the powder 5. A humidity sensor 27 and a temperature sensor 28 are integrated into the cover 9. The humidity sensor 27 measures the humidity of the powder 5 on the cover 9, and the temperature sensor 28 measures the temperature of the powder 5 on the cover 9.

[0022] These two sensors 27 and 28 transmit their measured values ​​to computer 23 via signals. Computer 23 is connected to the computer. For each parameter (humidity, temperature, particle size, particle size distribution, and flowability of powder 5), computer 23 compares the measured actual values ​​with the rated values ​​stored in computer 23. These rated values ​​can be obtained empirically, for example, by learning from completed tasks processed by printing press 1 using computer 23.

[0023] Computer 23 is connected to a Leitstand (not shown) of printing press 1 and transmits recommendations 29 for setting various parameters to the Leitstand based on the results of each rated-actual-comparison. The operator can read the recommendations 29 on the Leitstand and set the parameters accordingly, for example, by loading other powder types into the powder applicator 6. The results of each rated-actual-comparison, represented by the recommendations 29, can be visually displayed to the operator on the Leitstand, for example, in the form of a "traffic light." Green means that the parameter setting is optimal; yellow means that the setting is acceptable; and red means that the parameter setting should be corrected.

[0024] The analysis and processing unit 22 can operate continuously or discontinuously, for example, periodically, or for a defined period of time at the start of each printing job. In continuous operation, it can identify and correct not only batch fluctuations in the characteristics of powder 5, but also changes in the characteristics of powder 5 over time.

[0025] List of reference numerals

[0026] 1. Printing press

[0027] 2. Collector

[0028] 3 sheets of paper

[0029] 4. Stacking

[0030] 5 powders

[0031] 6. Powder Spreading Device

[0032] 7. Reserve cavity

[0033] 8 Exports

[0034] 9. Klappe (removable lid)

[0035] 10 Measuring cavity

[0036] 11 Metering chamber

[0037] 12 Exports

[0038] 13 Metering Rollers

[0039] 14 Piping System

[0040] 15 Mixing Chamber

[0041] 16 Compressed air

[0042] 17 Air connector

[0043] 18 Powder-Air-Mixture

[0044] 19 Distributors

[0045] 20 nozzles

[0046] 21 Powder rod

[0047] 22 Analysis and Processing Unit

[0048] 23 Computers

[0049] 24 cameras

[0050] 25 Scattered Bundles

[0051] 26 Vibrator

[0052] 27 Humidity Sensor

[0053] 28 Temperature Sensor

Claims

1. A method for sprinkling powder (5) onto printed sheets (3), wherein Measure at least one actual value of at least one parameter of the powder (5), Its features are, The parameters are the flowability, humidity, particle size, particle size distribution, and / or temperature of the powder (5). The actual value is measured in the measuring chamber (10) between the storage chamber (7) and the metering chamber (11) for the powder (5). The computer (23) performs a rated-actual comparison and analysis on each parameter against the rated value, and... The computer (23) outputs a recommendation (29) for parameter setting based on each rated-actual-comparison.

2. The method according to claim 1, Its features are, In the measuring chamber (10), the powder (5) is scattered during the measurement.

3. The method according to claim 1 or 2, Its features are, Each rating is determined based on experience.

4. The method according to claim 3, Its features are, The computer (23) obtains each rated value from the completed job tasks in a self-learning manner.

5. The method according to claim 1 or 2, Its features are, The analysis and processing unit (22) having the measurement cavity (10) and the computer (23) is permanently activated.

6. The method according to claim 1 or 2, Its features are, The analysis and processing unit (22) having the measurement cavity (10) and the computer (23) is temporarily activated.

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