EP2842747B1 - Rotary pad printing machine and method for printing an essentially cylindrical outer surface of an object to be printed - Google Patents

Description

TECHNICAL AREA

The present invention relates to a rotary pad printing machine for printing on a substantially cylindrical outer side of an object to be printed and to a method for operating such a rotary pad printing machine.

STATE OF THE ART

Pad printing machines are known in the prior art in numerous designs and are used for printing differently shaped objects. For this purpose, a print image is taken from a cliché by means of a printing pad and then transferred to an object to be printed. By forming the printing pad from an elastic material, it is also possible to print on comparatively uneven surfaces.

In order to print objects with a cylindrical outer side, rotary pad printing machines are particularly suitable. These allow a very fast and efficient circumferential printing of the outside of the object to be printed. For this purpose, a round tampon is used with a cylindrical outer surface, which is unrolled for print image recording on a likewise cylindrical cliché roller and at the same time for print image transmission on the outside of the object to be printed. In this way, rotary pad printing machines can be used to print a large number of objects in a relatively short time. Such Rotary pad printing machine is for example from the EP 1 447 219 known.

In the WO 93/08988 A1 a rotary pad printing machine according to the preamble of claim 1 and a method according to the preamble of claim 10 is disclosed, in which a round tampon and a printing material are each driven by separate drive units.

A difficulty in the operation of rotary pad printing machines is the correct positioning of the printed image along the circumferential direction of the object to be printed. In many applications, and especially in the medical field, it is often essential that the printed image is printed at a precisely predetermined position in the circumferential direction of the object to be printed , To achieve this, the object to be printed, the round tampon and the cliché roller must each be arranged in precisely defined rotational positions before the printing process can begin. Finding these rotational positions is difficult and often only possible by trial and error, since in particular the effective diameter of the round tampon during image transfer is difficult to estimate due to the elasticity of the round tampon. The setting of the rotary pad printing machine at a standstill by means of mechanically operated screws is also tedious for the user and takes a long time. In addition, having found the optimum rotational positions at the beginning of the printing process, each object to be imprinted has to be pre-positioned by hand or by technical means, which means a considerable additional expenditure for a large number of objects and is often difficult to achieve with the desired accuracy.

PRESENTATION OF THE INVENTION

It is therefore an object of the present invention to provide a rotary pad printing machine, which allows the simplest and most accurate printing of a printed image on an object to be printed with a substantially cylindrical outer side. To solve this problem, a rotary pad printing machine is proposed, as indicated in claim 1. Furthermore, a method for operating such a rotary pad printing machine is specified in claim 10. Advantageous embodiments of the invention are specified in the dependent claims.

The present invention thus provides a rotary pad printing machine for printing on a substantially cylindrical outer side of a printing object, which has a defined by the substantially cylindrical outer side longitudinal central axis. The rotary pad printing machine has
a cliché roll,
a round tampon with an at least partially cylindrical outer surface,
a first drive unit for driving the round tampon, as well
a Druckguthalterung for holding the object to be printed during printing.

With its outer surface, the round tampon can be unrolled on the cliché roll in order to take a printed image of the cliché roller, as well as to unroll on the object to be printed in order to transfer the printed image to the object to be printed. The rotary pad printing machine also has a second drive unit which is independent of the first drive unit and which serves to rotate the object to be printed about its longitudinal central axis.

In other words, the rotary pad printing machine has two axes driven independently of one another, in order, in each case, to put the round tampon and, on the other hand, the object to be printed into a rotational movement. The two axes of the round tampon and the object to be printed thus have in particular no mutual mechanical coupling. Because there are two separate drive units for the round tampon and for the object to be printed, the rotational positions taken by the round tampon and the object to be imprinted immediately before the print image transfer can be set and changed very easily, for example by means of a corresponding input in a user interface the rotary pad printing machine. Actuation of set screws is not necessary.

It has been recognized that the elasticity and diameter of the round tampon may change due to wear on printing on a large number of objects. As a result, the diameter of the round tampon during printing is gradually changed, which can lead to a distorted and circumferentially shifted printed image in rotary tampon printing machines of the prior art. With the rotary pad printing machine according to the invention, this effect can be counteracted simply by the fact that the rotational speed of the printing object is adjusted relative to that of the round tampon accordingly. For this purpose, for example, be stored in a control and monitoring unit for each used round pad relevant Ablutzungskoeffizient. By means of this wear coefficient, the control and monitoring unit can calculate the diameter of the round tampon, which is decisive in the print image transfer after a certain number of printing operations, and adjust the rotational speed of the round tampon accordingly.

The object to be printed may in particular be a product of medical technology, such as a syringe body to be printed with a scale. The substantially cylindrical outer side of the object to be printed can in particular also have a slightly conical design and have elevations and / or depressions.

The outer surface of the round tampon is at least partially cylindrical, which means that in the otherwise substantially cylindrical outer surface along the circumferential direction, one or more interruptions may be present, within which the round tampon each has a relatively smaller radial extent. With regard to the outside of the object to be printed as well as with respect to the outer surface of the round tampon, each outer side or outer surface which has the shape of a cone with an opening angle of less than 45 °, in particular of less than 30 ° and highest, is regarded as cylindrical in particular less than 10 °.

Advantageously, the round tampon has a Shore 00 hardness of 75 to 95, more preferably 80 to 90, and most preferably about 85. In particular, for the printing of conical and / or wavy surfaces, the round tampon but can also have a Shore 00 hardness in the range between 70 and 80. The round tampon adapts better to the surface due to its flexibility.

The first and the second drive unit serve to rotate the round tampon or the object to be printed during the print image transmission about their respective longitudinal central axis. These two rotational movements are preferred synchronized with each other such that the outside of the object to be printed and the outer surface of the round tampon have as much as possible identical speeds in their contact area. In order to allow the most accurate possible setting of the speed and the most precise adjustment of the rotational positions before the start of the print image transfer with respect to the round tampon or the object to be printed, the first drive unit and / or the second drive unit advantageously has a servomotor, which in particular with an angle encoder is equipped.

The rotary pad printing machine has an optical detection device which serves to detect a rotational position of the object to be printed. The optical detection device is preferably a camera, in particular a CCD camera. By means of the optical detection device, the rotational position of the object to be printed in the printing position, which is taken immediately before the print image transmission through the object to be printed, checked. If the determined rotational position should differ from a desired rotational position, this can be corrected automatically in particular by means of the second drive unit. For this purpose, the optical detection device is advantageously connected via a data line to a control and control unit which serves to control the drive units. In the control and control unit reference images may be stored, with the aid of a deviation of the rotational position of the desired rotational position, in particular automatically determined by the control and control unit itself. In the presence of an optical detection device, a pre-positioning of the objects to be printed even eliminated altogether.

Advantageously, the optical detection device is used not only for detecting the rotational position of the object to be printed before the print image transfer, but in addition to or instead of detecting the rotational position of the object to be printed with printed image after printing image transfer. By means of the optical detection device, the position of the printed image in the circumferential direction of the object to be printed can be controlled. Upon detection of a deviation, for example due to wear of the round tampon or due a not matching the requirements of tuning the rotary pad printing machine. With respect to the prepositioned objects to be printed, a correction can be made with regard to the printing of subsequent objects. In this way, the machine can also be finely adjusted before printing on a large number of prepositioned objects to be printed. If the print image is incorrectly positioned in the case of an object to be printed with a diameter which differs greatly due to manufacturing tolerances, this can be detected by the optical detection device and the corresponding object can be supplied to the reject, for example.

Advantageously, the rotary pad printing machine also has a third drive unit which is independent of the first and the second drive unit and which serves to rotate the plate roller and which in particular has a servomotor. This third drive unit thus serves to drive an axis connected to the plate roller, which in particular has no mechanical coupling with the axes of the round tampon and the object to be printed. By means of the third drive unit can be achieved in a circumferentially shifted imprinted printed image not only by a correction that the immediately before the start of the print image transmission by the object to be printed occupied rotational position is changed, but also in that instead the rotational position of the plate roller at the beginning of Print image transfer is adjusted. In this way, a correction can be made with respect to all subsequent objects to be printed, without having to subject each individual object to be printed to an additional correction rotational movement.

Preferably, the second drive unit has a first coupling element and the Druckguthalterung a second coupling element designed to be complementary to the first coupling element, in order to enable a coupling and decoupling of the second drive unit and the Druckguthalterung. As a result, a plurality of objects to be printed, which are each held in separate Druckguthalterungen, are printed one after the other, wherein the Druckguthalterungen are respectively coupled only in the printing position with the second drive unit.

Advantageously, the first coupling element or the second coupling element has an in Substantially conical shape, which in particular allows a positive engagement of the first and the second coupling element. As a result, a possible play-free coupling can be ensured. If, for example, the first coupling element has two conical, outwardly projecting elevations and the second coupling element correspondingly has two conical depressions, the two coupling elements can be coupled to one another even if they are not precisely aligned with one another. When the coupling elements are guided into one another, they self-align with one another until finally a form-fitting, backlash-free coupling is achieved.

Preferably, a central control unit is provided to control the first and the second and, if present, advantageously also the third drive unit. The control unit serves, in particular, to synchronize the rotational movements of the round tampon, the object to be printed and, if appropriate, the cliché roller.

The round tampon and the cliché roller are in particular lowered automatically in the direction of Druckguthalterung out. For this purpose, for example, a pneumatic drive or a linear motor can be provided.

In addition, the cliché roller is in particular automatically displaceable towards the round tampon along a radial direction of the round tampon. For this purpose, for example, a pneumatic drive or a linear motor can be provided.

The at least partially cylindrical outer surface of the round tampon usually has a substantially constant radius. Advantageously, the round tampon has a recess along its circumferential direction, within which the round tampon has a smaller radial extent than in the region of the at least partly cylindrical outer surface. By the round tampon is rotated such that this recess is opposite to the object to be printed or the plate roller, the object to be printed or the plate roller can be rotated without contact relative to the round tampon. Moving the object to be printed or the cliché roller away from the round tampon is not required for this purpose, thanks to the recess. Preferably, the recess extends over an angular range of 60 ° to 90 °.

To reduce the moment of inertia, the round tampon, the plate roller or the Druckguthalterung advantageously one or more openings. Preferably, the round tampon and the cliché roll each have one or more openings. If the object to be printed has a relatively large diameter and is held in particular in the region of its outer side by the Druckguthalterung, preferably also has the Druckguthalterung or a holding means of Druckguthalterung a inertia-optimized design with one or more breakthroughs. Due to the inertia-optimized training, which is achieved by the one or more breakthroughs, higher accelerations and thus a much faster control of the movements of the round tampon, the plate roller or the holding means of Druckguthalterung are possible. Preferably, the round tampon, the plate roller or Druckguthalterung it has the shape of a spoked wheel. The spokes can be connected to one another by means of struts, which are advantageously attached to the spokes approximately in half of the longitudinal extension of the spokes and in particular extend substantially perpendicular to the radial direction. The struts can in particular together form a ring.

Advantageously, the rotary pad printing machine also has a cleaning module which has at least one cleaning roller which can be driven by means of a fourth drive unit. This fourth drive unit, which may in particular comprise a servomotor, is designed independently of the first, the second and the third drive unit. At least one cleaning roller is preferably movable relative to the round tampon such that it can assume a position remote from the round tampon and, for the purpose of cleaning the round tampon, a position approximated to the round tampon. To reduce the moment of inertia, preferably at least one cleaning roller, advantageously all cleaning rollers, has one or more apertures. A cleaning roller or even all cleaning rollers advantageously have the form of a spoke wheel.

There is also provided a method of operating a rotary pad printing machine. The rotary pad printing machine is formed as described above and has at least a round tampon and a cliché roller and a first drive unit for driving the round tampon and one independent of the first drive unit second drive unit, which serves to rotate an object to be printed. The method has at least the steps defined in claim 10.

The synchronization is preferably carried out fully automatically by the rotary pad printing machine.

The rotations of the round tampon and the object to be printed can be synchronized with one another, for example, based on the position of a register mark provided on the object to be printed, the position of the register mark being detected, in particular, by means of an optical detection device. The register mark is, in particular, a rotational asymmetry formed on the outside of the object to be printed, for example a notch or a nose protruding outwards. In the presence of a register mark can be used as an optical detection device for detecting the rotational position of the object to be printed instead of a camera also a much cheaper optical sensor, such as a fork light barrier.

However, the rotations of the round tampon and of the object to be printed can also be synchronized with one another, for example, based on the position of a print image which was printed on an object to be printed in a previous print image transfer.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1

eine Vorderansicht einer Rotationstampondruckmaschine gemäss einer erfindungsgemässen Ausführungsform;

Fig. 2

eine perspektivische Ansicht der Rotationstampondruckmaschine der Fig. 1, beim Zuführen des zu bedruckenden Objekts zur Druckposition;

Fig. 3

eine perspektivische Ansicht der Rotationstampondruckmaschine der Fig. 1, bei Erreichen der Druckposition durch das zu bedruckende Objekt, unmittelbar vor dem Einkoppeln des Antriebsmoduls;

Fig. 4

eine perspektivische Ansicht der Rotationstampondruckmaschine der Fig. 1, unmittelbar nach dem Einkoppeln des Antriebsmoduls sowie dem Absenken des Druckmoduls;

Fig. 5

eine perspektivische Ansicht der Rotationstampondruckmaschine der Fig. 1, während der Druckbildübertragung;

Fig. 6

eine perspektivische Ansicht der Rotationstampondruckmaschine der Fig. 1, nach erfolgter Druckbildübertragung und mit abgesenktem Reinigungsmodul; sowie

Fig. 7

eine perspektivische Ansicht des Rundtampons der in der Fig. 1 gezeigten Rotationstampondruckmaschine.

Preferred embodiments of the invention will be described below with reference to the drawings, which are given by way of illustration only and are not to be interpreted as limiting. In the drawings show:

Fig. 1

a front view of a rotary pad printing machine according to an inventive embodiment;

Fig. 2

a perspective view of the rotary pad printing machine of Fig. 1 when feeding the object to be printed to the printing position;

Fig. 3

a perspective view of the rotary pad printing machine of Fig. 1 upon reaching the printing position by the object to be printed, immediately before the coupling of the drive module;

Fig. 4

a perspective view of the rotary pad printing machine of Fig. 1 , immediately after the coupling of the drive module and the lowering of the pressure module;

Fig. 5

a perspective view of the rotary pad printing machine of Fig. 1 during the print image transfer;

Fig. 6

a perspective view of the rotary pad printing machine of Fig. 1 , after print image transfer and with lowered cleaning module; such as

Fig. 7

a perspective view of the round tampon in the Fig. 1 shown rotary pad printing machine.

DESCRIPTION OF PREFERRED EMBODIMENTS

In the FIGS. 1 to 6 a rotary pad printing machine according to an inventive embodiment for printing a substantially cylindrical outer side 61 of an object to be printed 6 is shown. The rotary pad printing machine has a machine housing 1, a pressure module 2 slidably mounted thereto, a camera 3, and a rotary indexing table 4 with one thereon attached Druckguthalterung 5 on. The Druckguthalterung 5 serves to hold the object to be printed 6 during printing.

In the machine housing 1, among other things in the figures not visible control and monitoring units and various high and low voltage components housed, which are used in particular for the power supply and for driving the various components of the print module 2.

The printing module 2 is connected by means of rails 11 at the in FIG. 1 attached to the observer facing the front of the machine housing 1. In the figures, only one of the extending in the vertical direction rails 11 can be seen in each case. On the machine housing 1 but at least a second rail is mounted, which extends as well as the first rail 11 and parallel to this over substantially the entire height of the machine housing 1. The printing module 2 has a base plate 21 which is held guided in the rails 11 such that the printing module 2 as a whole is vertically displaceable relative to the stationary machine housing 1 by means of a pneumatic drive or linear motor arranged in the machine housing 1.

In the lower region of the base plate 21, a round tampon 23 is rotatably arranged, which has a substantially cylindrical outer surface 232. By means of a first drive unit not visible in the illustrations, the round tampon 23 can be set into a rotational movement. The first drive unit, which can be arranged, for example, in the interior of the base plate 21, in particular has a servomotor equipped with an angle transmitter, so that the rotation of the round tampon 23 can be controlled in a very precise manner.

The round tampon 23 has a radially outer region, which forms the outer surface 232 and adjacent thereto. This radially outer region has a Shore 00 hardness of about 80 to 90. The round tampon 23, which in particular in the FIG. 7 is well recognizable, has an overall shape of a spoked wheel with spokes 231, each extending in the radial direction. The spokes 231 are each about half of their Longitudinal extension by means of struts 234 connected to each other, so that the struts 234 together form a ring. The spokes 231 bound together with the struts 234 triangular and trapezoidal breakthroughs which are formed in the round tampon 23. Due to its spoked wheel-like shape with spokes 231 and struts 234 of the round tampon 23 is inertia moment optimized.

The outer surface 232 of the round tampon 23 is configured in the present embodiment is not completely cylindrical, but has a recess 233, within which the round tampon 23 has a smaller radial extent than in the region of circumferentially adjacent outer surface 232. The outer surface 232 is thus in the circumferential direction interrupted by the recess 233. The recess 233 extends over an angular range of 60 ° to 90 °.

On the underside of the machine housing 1 or on the inside of the basic unit 41 of the rotary indexing table 4 described below, a drive module 7 is mounted directly below the round tampon 23, which serves for rotating the object to be printed 6 during the printing operation. The drive module 7 has a housing 71, which is fixedly mounted on the machine housing 1 or on the base unit 41. Inside the housing 71, a servomotor is accommodated, which forms a second drive unit. This second drive unit of the drive module 7 is thus independent of the first drive unit, which serves to drive the round tampon 23. The servomotor disposed in the housing 71 has a drive shaft extending parallel to the center axis of the round tampon 23, which is non-rotatably connected to a coupling element 72 provided on the front side of the housing 71. The coupling member 72 has a conical shape provided with an engaging structure. The coupling element 72 is pneumatically displaceable relative to the machine housing 1 to the front of the rotary indexing table 4.

The base plate 21 has a laterally open recess 211, which extends slightly obliquely downward toward the central axis of the round tampon 23 out. Within the recess 211, a carriage 22 is arranged, which is for example pneumatically or by means of a linear motor in the longitudinal direction of the recess 211 to the round tampon 23 towards slidably.

On the carriage 22, a plate roller 24 is rotatably mounted, which is drivable in the present embodiment by means of a third drive unit in a rotational movement. The third drive unit may in particular be a servomotor, which is arranged in the interior of the carriage 22. The cliché roller 24 can thus be rotated as well as the object to be printed 6 regardless of the rotary tampon 23. Similar to the round tampon 23, the cliché roller 24 is designed as a spoke wheel with radial spokes 241 and thus optimized for inertia.

On the carriage 22 also known from the prior art doctor device 26 is mounted, which serves for doctoring the outer surface of the plate roller 24. Below the plate roller 24, a paint tray 25 is fixed to the base plate 21, which serves for color pickup by the plate roller 24.

Diagonally above the round tampon 23, a cleaning module 27 is provided on the base plate 21. The cleaning module 27 has a pneumatic displacement unit 271, which is arranged within a laterally and upwardly open recess or depression of the base plate 21. By means of the pneumatic displacement unit 271, a base plate 272 of the cleaning module 27 in the vertical direction to the round tampon 23 is displaced.

On the base plate 272, three respective rotatable cleaning rollers are mounted: an unwinding roller 273, a guide roller 274 and a take-up roller 275. The comparison with the unwinding roller 273 and the take-up roller 275 at the bottom and thus closest to the round tampon 23 arranged deflection roller 274 projects downwards slightly beyond the base plate 272. A cleaning tape, not shown in the drawings, is wound at a first end onto the unwind roll 273 and at a second end onto the wind-up roll 275. In between, it is tightly guided over the underside of the pulley 274. The winding roller 275 is drivable by means of a further servo motor, which forms a fourth drive unit, which is independent of the first, the second and the third drive unit.

The rotary indexing table 4 has an overall annular shape, due to which a in the vertical direction extending centrally located center axis 43 of the rotary indexing table is defined. The rotary indexing table 4 has a stationary relative to the machine housing 1 base unit 41 and a resting on the top of the base unit 41 rotary ring 42. The rotary ring 42 has a top surface extending in a horizontal plane and is rotatably mounted on the base unit 41 about the central axis 43. A not visible in the drawings drive for rotating the rotary ring 42 is housed in the base unit 41. The rotary indexing table 4 serves as conveying means for supplying the objects 6 to be printed to the printing module 2.

On the upper side of the rotary ring 42 usually a plurality of Druckguthalterungen 5 is mounted in advantageously regular intervals. For illustrative reasons, however, only a single of these Druckguthalterungen 5 is shown in the drawings 1 to 6.

The Druckguthalterungen 5 each have a housing 51 which is fixed to the upper side of the rotary ring 42. The Druckguthalterungen 5 also each have a holding means 53, in which an object to be printed 6 rotatably durable. The holding means 53 is formed such that the object to be printed on the 6. With respect to the center axis 43 of the rotary indexing table 4 radially outwardly facing front of the Druckguthalterung 5 is held. A longitudinal central axis 62 of the object 6 to be printed, which is defined by the substantially cylindrical outer side 61, extends outward in the radial direction.

The holding means 53 of the Druckguthalterung 5, which has in the present embodiment, an object to be imaged 6 projecting along the longitudinal central axis 62 mandrel is freely rotatably mounted on the housing 51 via a pivot bearing 52. The rotary bearing 52 may in particular be a ball bearing. The object to be printed 6 is thus held by the Druckguthalterung 5, that it is basically freely rotatable about its longitudinal central axis 62, which is in the radial direction with respect to. The rotary indexing table 4. The Druckguthalterung 5 also has a blocking mechanism with which the holding means 53 in the housing 51 can be blocked in such a way that a rotational movement of the object to be printed 6 relative to the housing 51 is limited or even completely impossible.

At the with respect to the center axis 43 of the rotary indexing table 4 radially inwardly facing back of Druckguthalterung 5 a not visible in the drawings coupling element is provided. This coupling element is designed to be complementary to the coupling element 72 of the drive module 7 and, in particular, has a recess that conically tapers into the interior of the housing 51, on the inner surface of which an engagement structure is provided. The engagement structure is formed complementary to the engagement structure which is provided on the coupling element 72. The coupling element is non-rotatably connected to the holding means 53, so that via the coupling element, a rotational movement on the held in the holding means 53 to be printed object 6 is transferable.

The camera 3 can be mounted, for example, on the machine housing 1, on the printing module 2 or also on the basic unit 41 of the rotary indexing table 4. However, the camera 3 is advantageously mounted in such a way that it is stationary with the machine housing 1 and the basic unit 41 of the rotary indexing table 4. The camera 3 is oriented such that it can detect the outside 61 of the object 6 to be printed immediately after the transfer of the printed image. Via a data line, not shown in the figures, the camera 3 is connected to a control and monitoring unit housed in the machine housing 1.

The operation of the rotary pad printing machine is described below by means of the FIGS. 2 to 6 illustrated picture sequence explained.

In the in the FIG. 2 shown situation is an object to be printed 6 held by means of the holding means 53 in the Druckguthalterung 5. By means provided in the Druckguthalterung 5 blocking mechanism, the holding means 53 is blocked relative to the housing 51, so that the object to be printed 6 rotatably held in the Druckguthalterung 5. Due to this blocking of the holding means 53 relative to the housing 51, the object to be printed 6 in a predetermined rotational position, ie prepositioned, the printing module 2 are supplied. The feeding of the object to be printed 6 to the printing module 2 is accomplished by a rotational movement of the rotary ring 42 relative to the base unit 41 of the rotary indexing table 4 in the direction of arrow a. The rotary ring 42 is thereby moved by the provided inside the base unit 41 drive. The printing module 2 is located in a position relative to the machine housing 1 upper position. The carriage 22 is in a position in which the cliché roller 24 is arranged at a distance from the round tampon 23, and the cleaning module 27 is in an upper position, so that the deflection roller 274 is arranged at a distance from the round tampon 23.

In the in the FIG. 3 As shown, the object to be printed 6 held in the printing stock holder 5 has reached the printing position, and the movement of the rotary ring 42 relative to the base unit 41 is stopped. The drive module 7 and the Druckguthalterung 5 are arranged directly opposite each other.

After reaching the printing position by the object to be printed 6, as in the FIG. 4 is shown, the coupling element 72 of the drive module 7 pneumatically with respect to the central axis 43 of the rotary indexing table 4 radially outwardly shifted (arrow b), so that the coupling element 72 is coupled to the provided on the back of the Druckguthalterung 5 coupling element. At the same time provided in the Druckguthalterung 5 blocking mechanism is released so that a rotational movement of the holding means 53 and thus of the object to be printed 6 is released relative to the housing 51. Due to the conical shapes of the two intermeshing coupling elements a particular backlash-free coupling between the drive module 7 and the Druckguthalterung 5 is achieved. The engagement structures, which are provided on the two coupling elements, thereby produce a torsion-proof connection between the two coupling elements.

After coupling, the rotational position of the object to be printed 6 is detected by the camera 3 and compared in the control and monitoring unit with a reference image. If necessary, the drive module 7 is then controlled by the control and monitoring unit so that the object to be printed 6 is rotated to the desired rotational position. As an alternative possibility, instead of the object 6 to be printed, the printing plate roller 24 can also be rotated by a certain angular range in order to correct a rotational position of the object 6 to be printed with respect to the printing process which deviates from a reference rotational position. A pre-positioning of the This printing object 6 can even be omitted entirely.

Further verification of the rotational position by the camera 3 and the control and monitoring unit and, if necessary, a further correction of the rotational position of the object to be printed 6 are possible. The checking of the rotational position can be carried out, in particular, by means of one or more register marks, e.g. are provided in the form of notches or protruding lugs on the object to be printed 6.

As soon as the desired rotational position of the object 6 to be printed has been reached, the printing module 2 is moved relative to the machine housing 1 in the direction of the arrow c (FIG. FIG. 4 ), so that the round pad 23 with its outer surface 232, the outer side 61 of the object to be printed 6 contacted.

After lowering the printing module 2, the actual printing process ( FIG. 5 ). For this purpose, the carriage 22 is displaced in the direction of the arrow d to the round tampon 23, so that the cliché roller 24 rests against its outer surface 232. By means of the first, the second and the third drive unit, the round tampon 23, the object 6 to be printed and the cliché roller 24 are then rotated (arrows e, f, g) so that the round tampon 23 receives a printed image from the cliché roller 24 and this the outside 61 of the object 6 to be printed transmits.

The rotational speed of the object to be printed 6 used during the print image transfer can be predetermined by the user, for example. Alternatively, the approximate diameter of the object 6 to be printed can be determined by means of the camera 3, so that the control and monitoring unit sets an optimum rotational speed of the object 6 to be printed for the print image transmission based thereon. Optimal rotational speeds for different diameters of objects to be printed can be stored in a database of the control and monitoring unit for this purpose. The movements of the round tampon 23 and the cliché roller 24 are synchronized by the control and monitoring unit with the movement of the object 6 to be printed. Accordingly, the rotational speeds of the round tampon 23 and the cliché roller 24 are controlled by the control unit based on the rotational speed of the printed object 6 is calculated and set. In particular, the diameters of the object 6 to be printed and the plate roller 24 as well as the diameter of the round tampon 23 which is decisive during the print image transfer are used as calculation parameters. Due to the wear and the associated change in the elasticity of the round tampon 23, the decisive during the print image transmission diameter of the round tampon 23 changes over time. The control and monitoring unit therefore advantageously measures the operating time of the round tampon 23 and continuously adjusts the diameter of the round tampon 23 used in the calculation based thereon. In particular, empirical values stored in a database regarding the wear of round tampons can be used for this purpose. A mutual slippage of the round tampon 23 which gradually changes as a result of wear and tear with respect to the object 6 to be printed on the one hand and the cliché roller 24 on the other hand can thereby be avoided.

After the print image transfer, as it is in the FIG. 6 is shown, the printing module 2 relative to the machine housing 1 and the rotary indexing table 4 is raised (arrow h), so that the round tampon 23 is no longer in contact with the object to be printed 6. The carriage 22 is moved away from the round tampon 23 (arrow i), so that the cliché roller 24 is arranged at a distance from the round tampon 23.

By means of the camera 3 can then be detected on the object 6 printed image. In order to control the position of the printed image in the circumferential direction of the outside 61, the printed image captured by the camera can be compared with a reference image by means of the control and monitoring unit. Upon detection of a deviation, the already printed object 6 can be supplied to the committee. In addition, the determined deviation can also be used to redefine the start positions of the round tampon 23, the cliché roller 24 and / or the subsequent objects to be printed 6 in order to avoid repeated errors in further printing operations.

As the next step, after the printing module 2 has been raised and the carriage 22 has been moved away from the round tampon 23, the rotation 42 of the rotary indexing table 4 is further rotated in the direction of the arrow j to the object 6 for further processing supply. At the same time, a subsequent object to be printed 6, which in the FIG. 6 however, not shown, brought into the printing position.

During further rotation of the rotary ring 42, the cleaning module 27 is moved by means of the pneumatic displacement unit 271 downwards (arrow k), so that the cleaning tape in the region of the guide roller 274 contacts the round pad 23. By means of the corresponding servomotors, the round tampon 23 and the winding roller 275 are then rotated such that the cleaning belt is unwound via the underside of the deflection roller 274 from the unwinding roller 274 such that the underside of the cleaning belt is slightly in contact with the outer surface 232 of the round tampon in the mutual contact region has different speed. Due to these slightly different speeds, a small mutual slip between round tampon 23 and cleaning tape, which causes an efficient cleaning of the outer surface 232 of the round tampon 23, since dirt particles are absorbed by the cleaning tape.

After cleaning, the cleaning module 27 is raised again, and the entire process is performed again to transfer a printed image to the subsequent object to be printed 6.

Thanks to the recesses 233 provided on the rotary tampon 23, in order to take up a rotational position relative to the round tampon 23 between two successive printing operations, the cliché roller 24 need not necessarily be brought into a position away from the round tampon 23 by the method of the carriage 22. The round tampon 23 can instead be rotated so that the recess 233 directly opposite the plate roller 24 (see FIG. 4 ), so that the plate roller 24 can be rotated without touching the round tampon 23. In this way, the recess 233 can be used to rotate the plate roller 24 immediately before the printing of an object to be printed 6 in another rotational position, for example, if the object to be printed 6 is present in a different rotational position from a reference position. Furthermore, analogously, the object to be printed 6 can be rotated without contact with the round tampon 23 when the printing module 2 is in its lowered position and the recess 233 directly to the object 6 to be printed opposite. Because of the recess 233, a plurality of objects to be printed can thus be printed one after the other, whereby the printing module 2 can be left permanently in its lowered position and the carriage 22 in the position close to the round tampon 23, even when correction rotational movements are carried out. Since no time-consuming displacements of the carriage 22 and / or the printing module 2 are necessary in this way, the throughput can be significantly increased.

The present invention is of course not on in the Figures 1-7 illustrated embodiment limited. A variety of modifications is possible. For example, a camera does not necessarily have to be present, but another optical detection device, such as a laser measuring device, could be used for the same purpose. The cliché roller 24 could also be driven by a toothed belt connected to the round tampon 23 or by friction with the round tampon 23 instead of being driven by a servomotor. The same applies to the unwinding roller 273, which does not necessarily have to be driven by a servomotor. The displacement of the pressure module 2 can also, like the displacement of the carriage 22 and the cleaning module 27 instead of pneumatically or by means of a linear motor by hand, z. B. by means of screws, done. LIST OF REFERENCE NUMBERS 1 machine housing 11 rail 3 camera 2 print module 4 Rotary table 21 baseplate 41 basic unit 211 recess 42 rotating ring 22 carriage 43 central axis 23 around tampon 231 spoke 5 Druckguthalterung 232 outer surface 51 casing 233 recess 52 pivot bearing 234 pursuit 53 holding means 24 cliché role 241 spoke 6 Object to be printed 25 paint tray 61 outside 26 doctor device 62 Longitudinal central axis 27 cleaning module 271 Pneumatic displacement unit 7 drive module 272 baseplate 71 casing 273 unwinding 72 coupling element 274 idler pulley 275 up roll a, b, c, d, e, f, g, h, i, j, k arrows

Claims (13)

1. Rotational pad printing machine for printing of an essentially cylindrical outer side (61) of an object to be printed (6), which has a longitudinal center axis (62) defined by the essentially cylindrical outer side (61), comprising

   a cliché drum (24),

   a round pad (23) with an at least partly cylindrical outer face (232),

   a first drive unit for driving the round pad (23),

   a second drive unit (7) that is independent of the first drive unit and serves for rotation of the object to be printed (6) about its longitudinal center axis (62),

   a print article holder (5) for holding the object to be printed (6) during the printing,

   as well as a detection device (3) for the detection of a rotational position of the object to be printed (6),

   wherein the round pad (23) can both be rolled with its outer face (232) on the cliché drum (24), in order to take up a printing image from the cliché drum (24), and is also suited to roll on the object to be printed (6), in order to transfer the printing image onto the object to be printed (6),

   characterized in that

   the detection device (3) is in the form of an optical detection device (3) for detecting the rotational position of the object to be printed (6) in the print position, and that

   the round pad (23) as well as the cliché drum (24) can be lowered in a direction towards the print article holder (5), wherein the cliché drum (24) can be displaced along a radial direction of the round pad (23) towards the round pad (23).
2. Rotational pad printing machine according to claim 1, wherein the first drive unit and/or the second drive unit (7) comprises a servomotor.
3. Rotational pad printing machine according to one of claims 1 or 2, wherein the optical detection device (3) serves for the detection of a rotational position of the object to be printed (6) with printed printing image after completed transfer of the printing image.
4. Rotational pad printing machine according to one of the preceding claims, additionally comprising a third drive unit that is independent of the first and of the second drive unit (7), and which serves for the rotation of the cliché drum (24) and in particular comprises a servomotor.
5. Rotational pad printing machine according to one of the preceding claims, wherein the second drive unit (7) comprises a first coupling element (72) and the print article holder (5) comprises a second coupling element constructed complementary to the first coupling element (72), in order to enable a coupling and a decoupling of the second drive unit (7) and the print article holder (5).
6. Rotational pad printing machine according to claim 5, wherein the first coupling element (72) or the second coupling element comprises a conical shape.
7. Rotational pad printing machine according to one of the preceding claims, wherein a central control unit for controlling of the first drive unit and of the second drive unit (7) is provided.
8. Rotational pad printing machine according to one of the preceding claims, wherein the at least partly cylindrical outer face (232) of the round pad (23) has a constant radius, and wherein the round pad (23) comprises a cut-out (233) along of its circumferential direction, within which the round pad (23) has a smaller radial extension than in the region of the at least partly cylindrical outer face (232).
9. Rotational pad printing machine according to one of the preceding claims, wherein the round pad (23), the cliché drum (24) or the print article holder (5), in order to reduce the moment of inertia, comprises one or more apertures and in particular has the form of a spoke wheel.
10. Method for operation of a rotational pad printing machine according to one of the preceding claims with at least one round pad (23) and a cliché drum (24) as well as with a first drive unit for driving the round pad (23) and with a second drive unit (7) that is independent of the first drive unit and serves for rotation of an object to be printed (6), wherein the method comprises at least the following steps:

    - Taking up of a printing image by means of the round pad (23) from the cliché drum (24); as well as

    - Rolling of the round pad (23) on an essentially cylindrical outer face (61) of an object to be printed (6), in order to transfer the printing image from the round pad (23) onto the object to be printed (6), wherein during the transfer of the printing image onto the object to be printed (6), the round pad (23) is rotated by means of the first drive unit and the object to be printed (6) is rotated by means of the second drive unit (7), and wherein these two rotations of the round pad (23) and of the object to be printed (6) are such synchronized with each other, that the printing imaged is printed onto the object to be printed (6) on a predetermined position along the circumferential direction of the outer side (61) of the object to be printed (6);

    wherein a rotational position of the object to be printed (6) is detected by means of a detection device (3);

    characterized in that

    the rotational position of the object to be printed (6) is detected in the print position by means of the detection device (3) which is in the form of an optical detection device (3), and that

    the round pad (23) as well as the cliché drum (24) are lowered in a direction towards the print article holder (5), wherein the cliché drum (24) is displaced along a radial direction of the round pad (23) towards the round pad (23).
11. Method according to claim 10, wherein the synchronization is carried out fully automatically by the rotational pad printing machine.
12. Method according to one of claim 10 or 11, wherein the rotations of the round pad (23) and of the object to be printed (6) are synchronized with each other by means of the position of a registration mark provided on the object to be printed (6), and wherein the position of the registration mark is detected by means of the optical detection device (3) provided on the pad printing machine.
13. Method according to one of claims 10 to 12, wherein the rotations of the round pad (23) and of the object to be printed (6) are synchronized with each other by means of the position of a printing image which has been printed onto an object to be printed (6) in a previous printing image transfer.

Images