EP1447219B1 - Printing machine in particular rotary pad printing machine and method for printing objects with at least a printing module - Google Patents

Description

The invention relates to a printing machine, in particular rotary pad printing machine with at least one receiving means, which has a plurality of mutually spaced receptacles, on each of which an object to be printed is to attach and with at least one printing module with which said items are printable in continuously running recording medium. Printing machines of the type mentioned are known and are used in particular for printing uneven objects, such as bottle caps or keyboards. For multi-color printing several printing modules are provided in succession accordingly. In principle, however, a single-color printing with only one printing module is possible.

The invention also relates to a method for printing articles with at least one tampon doffer module.

In the known rotary pad printing machines, the printing module has a paint tray into which a inking roller dips. This inking roller colors a cliché roller, from which excess ink is removed by means of a squeegee device. The Cliché roller dyes a pad roller which prints objects one after the other. In a known machine, the objects on the circumference of a wheel are each mounted on a receptacle. The wheel turns continuously and the objects are printed accordingly on the stationary printing modules. A loading device brings the objects to be printed on the wheel and after printing the objects are removed with an unloading the wheel and sent for further processing.

With the mentioned machine, many items can be printed inexpensively. For example, 60 to 80 items are printed with each cycle. The peripheral speed is, for example, 0.5 m / sec. For certain items, greater precision would be desirable with comparatively hollow performance.

The DE-A-195 10 677 discloses a pad printing machine in which the printing process begins with the detection of the incoming print material over an optical sensor. A control computer determines from the sensor signals for beginning and end and other properties of the printed material, the delay times for placing and lifting the pad roller on the pad roller and the mating roller on the pad roller and initiates these operations accordingly.

The invention has the object of developing a printing machine of the type mentioned so that a precise pressure and higher performance is possible. The printing machine should still be reliable and inexpensive to produce.

The object is achieved in a generic printing press characterized in that the receiving means are driven by a first drive and the printing module of a second, highly dynamic drive and that this second, highly dynamic drive controls the printing module so that compensates for this manufacturing tolerances of the receiving means automatically.

By adapting the print module to the individual positions of the images, tolerances between the objects to be printed and between the images can be exactly compensated. The highly dynamic second drive thus controls the pressure module according to the positions of the objects or recordings. The receiving means, which is designed in particular as a wheel, can rotate during printing at a constant speed. It has been shown that with the novel printing machine a precision is achievable that enables digital printing. According to a development of the invention, the printing module is a digital printing module.

According to a development of the invention, measuring means are provided with which the distances between the recordings can be determined for controlling the printing module. According to a further development of the invention, these measuring means comprise a rotational angle sensor on the receiving means for determining the distances between the recordings. Preferably, by means of a light sensor, the beginning and the end of the distance measurements are respectively indicated. A particularly accurate measurement results when, according to an embodiment of the invention, the light sensor is arranged so that it is interrupted in each case by a recording.

According to a development of the invention induction sensors are provided to position the receiving means and the printing module. As a result, a particularly precise control is possible.

According to a development of the invention, the printing machine according to the invention is designed so that the distances between the recordings in a learning run can be determined. The determined distances between the recordings are stored in a register and due to these distances, the print module is controlled. Division tolerances between the recordings can thus be compensated very accurately.

According to a development of the invention, the clichés are determined on the cliché roller and tolerance deviations in the positions of the clichés are also taken into account in the control. This enables a particularly precise print.

Further advantageous features will become apparent from the dependent claims, the following description and the drawings.

Figur 1

schematisch eine Seitenansicht einer erfindungsgemässen Druckmaschine, wobei Teile aus zeichnerischen Gründen weggelassen sind,

Figur 2

schematisch die Kompensation von Teilungstoleranzen zwischen Aufnahmen,

Figur 3

schematisch eine Ansicht eines Druckmoduls, wobei Teile aus zeichnerischen Gründen weggelassen sind,

Figur 4

eine weitere schematische Ansicht des Druckmoduls gemäss Figur 3, wobei auch hier aus zeichnerischen Gründen Teile weggelassen sind und

Figur 5

schematisch der Antrieb des Aufnahmemittels, der Tamponwalze und der Cliché-Walze sowie die Position der Sensoren.

An embodiment of the invention will be explained in more detail with reference to the drawing. Show it:

FIG. 1

1 is a schematic side view of a printing machine according to the invention, with parts being omitted for reasons of drawing;

FIG. 2

schematically the compensation of pitch tolerances between recordings,

FIG. 3

2 is a schematic view of a printing module with parts omitted for illustrative purposes;

FIG. 4

a further schematic view of the printing module according to FIG. 3 , where parts are omitted here for drawing reasons and

FIG. 5

schematically the drive of the receiving means, the pad roller and the cliché roller and the position of the sensors.

In the FIG. 1 The printing machine shown is a rotary pad printing machine and has a machine frame 2, on which a wheel-shaped receiving means 5 is rotatably mounted on an axis 7. At the periphery of the receiving means 5 receptacles 6, for example mandrels are arranged, each of which has a in FIG. 2 shown item 8, for example, a bottle cap, record. The bottle cap 8, for example, releasably latched onto the receptacles 6. The feeding of the articles 8 takes place with a feeding device 3, which supplies the articles 8 individually. The items 8 would be consecutive printed in three-color printing by three printing modules A, B and C. After printing, the objects 8 are removed by means of a discharge device 4 from the receiving means 5 and supplied for further processing. The objects 8 thus leave the receiving means 5 within one revolution. On the receiving means 5, for example, 60 to 80 receptacles 6 are arranged, so that per revolution of the receiving means 5 thus 60 to 80 items 8 can be printed. The receiving means 5 is not necessarily formed radförmig, but may for example also be formed by an endless chain or the like.

The receiving means 5 is driven by a first drive 9 at a constant rotational speed. The drive is independent of the drive of the print modules A, B and C.

The printing modules A to C can all be made the same. They each print different colors, which in this case result in a three-color print. In principle, however, an embodiment with only one printing module, for example, with the printing module A is conceivable.

The Figures 3 and 4 show the printing module A, which has a housing 2, on which a Einfärbewalze 14, a Cliche roller 15, a pad roller 17 and a cleaning roller 28 of a cleaning device 25 are rotatably mounted. The inking roller 14 dips into a paint tray 13 and colors the cliché roller 15. A known squeegee device 20 rakelt the peripheral surface of the Cliché roller 15 from. Two scraper arms 27 strip the side surface of the Cliché roller 15 and remove in this way lateral color residues. The cliché roller 15 dyes the pad roller 17 in a known manner, so that printed images 26 are present at regular intervals on the peripheral surface 32 of the pad roller 17. By means of the cleaning roller 28 which heats is removed, remaining color from the peripheral surface 32.

The pad roller 17 has a rubber-elastic body 33 which is secured against rotation on a core 34. The core 34 sits on a shaft 35 which is in FIG. 4 is visible and which projects into the housing 12 and sits on a not shown here spur gear. This spur gear forms with two further spur gears 21 and 22, a gear 30 with which the pad roller 17 and the cliché roller 15 are driven. The spur gears 21 and 22 each consist of two sub-wheels, which are braced against each other for receiving a backlash. The gear 30 is formed so that the cliché roller 15 is rotated correspondingly faster according to its smaller circumference and no slip occurs between the cliché roller 15 and the pad roller 17. The cleaning roller 28 is driven by friction on the pad roller 17. The inking roller 14 is driven by friction from the cliché roller 15.

The highly dynamic second drive 10 has a servo motor 11 which is mounted on the housing 12 and which drives the spur gear 21 of the transmission 30. The spur gear 21 meshes with the above-mentioned and not visible here spur gear, which sits on the drive shaft 35. This spur gear meshes with the spur gear 22 which is mounted on the drive shaft 36 of the cliché roller 15. The cliché roller 15 and the pad roller 33 are thus mechanically fixedly coupled to each other via the gear 30. As already explained above, the highly dynamic drive 10 is independent of the first drive 9 of the receiving means 5.

The receptacles 6 of the receiving means 5 are according to FIG. 2 each arranged at a distance D to each other, as in FIG. 2 is shown. Due to manufacturing tolerances, these distances are not exactly the same. In FIG. 2 is the distance between the receptacle 6 and the receptacle 6 'D-0.5 mm and the distance between the receptacle 6''and the receptacle 6''' D + 0.5 mm. Of course, the deviations can also be smaller here, for example 0.1 mm. Due to these deviations, the prints on the objects 8, 8 ', 8''and8''' would be shifted accordingly. In order to obtain an exact pressure for all objects 8 despite these dimensional deviations from the exact graduation measure, all distances D are determined in a learning run and stored in a register of a controller, not shown here. To determine the distances D is according to FIG. 5 arranged on the shaft 7 of the receiving means 5 a Drehwinkelaufnehmer S1. In addition, a stationary light sensor S3 is arranged on the circumference of the receiving means 5, which forms a light barrier, which is interrupted by the receptacles 6 during rotation of the receiving means 5. The light sensor S3 starts or ends the distance measurements of the rotational angle sensor S1. In a learning drive, the recording means 5 is rotated at a constant but reduced speed. The rotational angle sensor S1 and the light sensor S3 are activated in this case and determine all distances D between adjacent recordings 6. These measured values are stored in the named register. To determine the positions of the receiving means 5 and the pad roller 17, an inductive sensor S2 or S2 'are arranged on each of these, as shown in FIG FIG. 5 is shown. These inductive sensors S2 and S2 'are each arranged at a distance from the corresponding axis of rotation. With the aid of these inductive sensors S2 and S2 ', the receiving means 5 and the pad roller 17 can be accurately positioned.

Due to the mentioned distance measurements during the learning run, the printing modules A, B and C are controlled so that said Manufacturing tolerances are automatically compensated. This will be explained below with reference to FIG. 2 explained in more detail.

During printing, the receiving means 5 is driven at a constant speed, which in FIG. 2 is indicated by the straight line 37. This speed is determined by the first drive 9. The speed of the pad roller 17, however, is not constant and in FIG. 2 indicated by the line 36. The lines 36 and 37 indicate according to the double arrow 38, the speed over time. The curves 36 and 37 will be explained with reference to the printing module A. The same applies to the printing modules B and C.

If the printing module A is in engagement with the receptacle 6 or the object 8, then this object 8 is printed with the pad roller 17. The speeds of the receiving means 5 and the pad roller 17 are exactly the same and constant during this procedure. During the learning run, the distance between the pickup 6 and 6 'was measured and this measurement showed that this distance is smaller than the setpoint. There is thus a distance C1 between the objects 8 and 8 'which is smaller than the desired value. To compensate for this shortening of the distance, the second drive 10 after the printing of the article 8 is controlled so that the speed corresponding to said reduction in distance according to the curve K1 reduced and until the beginning of the new pressure of the article A 'back to the speed of the first drive and thus to the speed of the curve 37 is raised. The course of the curve K1 is in FIG. 2 only given for example. The course can also be different. The article 8 'is thus again printed at a constant speed of the second drive 10. The distance D between the receptacles 6 'and 6''corresponds to the desired value. Between the objects 8 'and 8 ", therefore, the speed of the second drive 10 is not changed. By contrast, the distance between the objects 8 '' and 8 '''is greater than the nominal value between the recordings 6''and6''', and in this range of the distance C2 the velocity now becomes greater of the second drive 10 increases, as in FIG. 2 is indicated with the curve K2. The speed of the drive 10 is thus increased briefly and then falls back to the speed of the curve 37 back. Due to the accelerations according to curves K1 and K2, the stated manufacturing tolerances can be compensated very precisely. Due to these compensations, the printed images 26 of the pad roller 17 are each accurately positioned with respect to the articles 8 to 8 '''. This of course applies to all items to be printed. The mentioned learning trip is basically only necessary once for each shot 5. After a change of recording 5, a new learning run is performed and the corresponding distances are stored in said register. In principle, however, a learning run can also be carried out before each recording of a new print series. It is also conceivable, however, an embodiment in which said distances D are measured directly during operation. However, a low-speed learning run results in a particularly accurate measurement.

The printing modules A, B and C are according to the embodiment shown pad printing modules. Due to the high printing accuracy and a raster print is possible. On the three pad rollers 17 in this case, for example, in each case one image part in a basic color. These image parts are then added to each object to the image.

Tolerance deviations may also occur on the cliché roller 15, in particular the distances between the clichés may deviate from the nominal value, which may likewise lead to deviations in the pressure. In order to compensate for these tolerance deviations, the positions of the clichés are measured with a measuring device, not shown here, for example a laser measuring device, and the corresponding measured values are stored in the register. By controlling the second drive 10, these deviations can also be compensated.

Claims (15)

1. Printing machine, in particular rotary pad printing machine, having at least one holding means (5) which has a plurality of holders (6) arranged at a distance from one another, on which an object (8) to be printed is respectively to be fixed, and having at least one printing module (A, B, C), with which the aforementioned objects (8) can be printed with the holding means (5) moving constantly, the holding means (5) being driven by a first drive (9) and the printing module (A, B, C) being driven by a second, highly dynamic drive (10), and this second, highly dynamic drive (10) activating the printing module (A, B, C) in such a way that the printing module (A, B, C) is adapted independently to the positions of the objects (8) to be printed and, as a result, it is possible to compensate independently for production tolerances of the holding means (5).
2. Machine according to Claim 1, characterized in that the holding means (5) is a wheel, and in that the holders (6) are arranged on the periphery of this wheel.
3. Machine according to Claim 1 or 2, characterized in that the holding means (5) is driven at constant speed.
4. Machine according to one of Claims 1 to 3, characterized in that measuring means (S1, S3) are provided, with which the distances (D) between the holders (6) can be determined.
5. Machine according to Claim 4, characterized in that the measuring means has a rotary encoder (S1), which is arranged on the drive shaft (7) of the holding means (5).
6. Machine according to Claim 5, characterized in that the measuring means has a light sensor (S3), which respectively indicates the start and the end of a distance measurement between adjacent holders (6, 6').
7. Machine according to Claim 6, characterized in that the light sensor (S3) forms a light barrier.
8. Machine according to one of Claims 1 to 7, characterized in that the printing module (A, B, C) is a round printing module having a pad roll (17) .
9. Machine according to Claim 8, characterized in that the pad roll (17) is mechanically firmly connected to a cliché roll (15).
10. Machine according to Claim 9, characterized in that the pad roll (17) and the cliché roll (15) are firmly coupled to each other by a gear mechanism (30).
11. Machine according to one of Claims 1 to 10, characterized in that the second drive (10) has a servo motor (11).
12. Machine according to one of Claims 1 to 11, characterized in that the printing module (A, B, C) is a digital printing module.
13. Method for printing objects with at least one printing module, having at least one holding means (5) which has a plurality of holders (6) arranged at a distance from one another, on which an object (8) to be printed is respectively to be fixed, and having at least one printing module (A, B, C), with which the aforementioned objects (8) are printed with the holding means (5) moving constantly, characterized in that the holding means (5) is driven by a first drive (9) and the printing module (A, B, C) is driven by a second, highly dynamic drive (10), and this second, highly dynamic drive (10) activates the printing module (A, B, C) in such a way that the printing module (A, B, C) is adapted independently to the positions of the objects (8) to be printed and production tolerances of the holding means (5) are independently compensated for.
14. Method according to Claim 13, characterized in that the holding means (5) are driven at constant speed.
15. Method according to Claim 13, characterized in that measuring means (S1, S3) are provided, with which the distances (D) between the holders (6) are determined in a learning cycle.

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