WO2007033752A1

WO2007033752A1 - Printing press and method for printing workpieces, especially fabrics

Info

Publication number: WO2007033752A1
Application number: PCT/EP2006/008536
Authority: WO
Inventors: Herbert Mayrhofer
Original assignee: Mhm Siebdruckmaschinen Gmbh Kg
Priority date: 2005-09-16
Filing date: 2006-08-31
Publication date: 2007-03-29
Also published as: DE502005006656D1; ATE423003T1; EP1764217B1; HK1102572A1; EP1764217A1

Abstract

The invention relates to a printing press and a method for printing workpieces, particularly fabrics. A revolving table (20) comprising a plurality of workpiece supports (34) is mounted on a machine frame (12) so as to be rotatable about an axis of rotation (22). In addition, several screen printing stations (42) as well as at least one digital printing station (60) encompassing at least one triggerable discharge nozzle for complementarily printing the workpieces are provided. The digital printing station (60) is non-positively and/or positively coupled to a workpiece support (34) during the printing process.

Description

Printing machine and method for printing on workpieces, in particular textiles

The invention relates to a printing machine for printing on workpieces, in particular textiles, with a machine bed, a plurality of screen printing stations, which are arranged on the machine bed, a turntable, which has a plurality of workpiece carriers and rotatably mounted on the machine bed about a rotation axis and for gradually conveying the workpieces the screen printing stations is driven, and at least one digital printing station.

The invention further relates to a method for printing on workpieces, in particular textiles, wherein the workpieces are clamped on workpiece carriers, which are arranged on a turntable, which is rotatably mounted on a machine bed, the workpieces are conveyed by stepwise driving the turntable to working positions at which the workpieces are each printed by a screen printing station, and the workpieces are printed by at least one digital printing station.

A printing press with several Siebdruckstaitonen and a digital printing station is known for example from US 6,397,740 Bl.

So-called carousel screen printing machines are particularly suitable for printing on textiles in medium and large sizes Efficient use of quantities. If a change or even a change in the motif to be printed is made, it is necessary to remove one or more screen printing stencils in the screen printing stations and to use a corresponding new or modified screen stencil. For a frequent change of motif or for printing individual motifs, a digital printing station can be used. At the widely projecting workpiece carriers, in particular at high rotational step speeds, fluctuations can occur which can impair the printing result of the digital printing station.

The invention is based on the invention to provide a printing press and a printing method, which allow a particularly efficient operation.

The object is achieved according to the invention by a printing machine having the features of claim 1 and by a method having the features of claim 8. Preferred embodiments are given in the respective dependent claims.

In the printing machine according to the invention at least one digital printing station is arranged with at least one controllable jet nozzle for supplementary printing of the workpieces. The digital printing station allows an efficient and flexible change or adaptation of an imprint on the workpiece to be printed. For example, a serial number, a date, a supplementary logo, a name, etc. can also be printed on the screen-printed motif. It is also readily possible to carry out desired modifications or overlaps at the standard motif to be applied by the screen printing stations. the. This is done by simple electronic control of the digital printing station. It is not necessary to interrupt the printing operation by exchanging screen printing stencils, which considerably increases the efficiency of the printing press. With regard to the relative lifting movement, this can be effected for example by moving the printing stations and / or the rotary table.

According to the invention, it is possible for the at least one digital printing station to be non-positively and / or positively coupled to the workpiece carrier when printing on a workpiece. This can be done for example by pressure elements, extendable bolts, clamping jaws or other coupling elements, in particular at the printing station, wherein the digital printing station is additionally firmly connected to the workpiece carrier. This counteracts the occurrence of vibrations between the workpiece carrier and the digital printing station. This ensures high print quality and enables higher working speeds.

According to the invention, it is preferred that the screen printing stations are arranged together on a printing plate which is mounted on the machine bed and that a lifting device is provided for the axial displacement of the printing plate with the screen printing stations relative to the turntable, wherein the printing plate for printing approximated the turntable and the stepwise conveying the turntable is removed. In this lifting movement, the mechanical coupling movement can be performed. The coupling movement can also be done magnetically by electrically controllable magnetic element.

A further improvement over the influence of undesired vibrations is inventively achieved by It is sufficient that the at least one digital printing station is stored separately from the printing plate with the screen printing stations. The printing plate with the screen printing stations is moved axially up and down, while the turntable is driven in rotation with the star-shaped projecting workpiece carriers in the start-stop mode. This can cause vibrations of the overall construction. Although these play a minor role in screen printing for operational reasons, since the screen printing station with the screen printing stencil is placed directly on the workpiece. In the case of the digital printing station, however, the at least one ink jet nozzle is operationally spaced from the workpiece, so that vibrations occurring here can have a significant influence on the print quality. By decoupling the digital printing station from the printing plate with the screen printing stations, the occurrence of undesired vibrations at the digital printing station can be substantially counteracted.

In principle, it is possible to attach a digital printing station on the printing plate in place of a screen printing station and optionally decouple by interposing a damping element vibrationally from the pressure plate. However, it is preferred according to the invention that the pressure plate is connected above the printing table with the machine bed and that the at least one digital printing station below the turntable connected to the machine bed or stored separately from the machine bed directly on the ground. In this way, a transfer of the significant oscillations in the upper part of a carousel printing press to the digital printing station is largely avoided. The immediate location of the digital printing station on the lower machine bed leads to an improved rigidity of the storage of the di- digital printing station. At the same time while a defined position of the digital printing station is guaranteed over the other machine elements. Alternatively, however, the digital printing station can be set up and attached directly to the ground as a separate element separate from the machine bed. As a result, practically a complete vibration decoupling is achieved.

To improve the print quality of the total pressure, it is according to the invention that the workpiece carrier and / or the workpiece can be provided with a marking and that the at least one digital printing station has a sensor for detecting the marking and an adjusting device, with which the at least one jet nozzle is adjustable. As a result, an exact alignment of the individual imprints is achieved by the digital printing station.

According to the invention, it is advantageous that for adjusting the pressure output, the at least one jet nozzle is height-adjustable relative to the workpiece. By height adjustability of the jet nozzle, in particular during the linear or cellular printing application, the inking performance can be changed, in particular increased. If the distance is increased, the spray cone covers a larger area on the workpiece. Optionally, the ink throughput can be increased simultaneously with a larger distance of the jet nozzle to the workpiece, so that further sufficient application of the pressure medium is achieved. Alternatively, however, a graphic special effect, such as misting, can be achieved with a height adjustment and a lowering of the color passage.

An advantageous aspect of the invention is further that the power stroke of the screen printing stations and the at least one digital printing station is the same, in particular between 0.5 to 5 seconds, preferably between 1 to 2 seconds. The working cycle of the entire machine is still ensured by the fast and thus shortest working cycle of the screen printing station. The digital printing station has to adhere to this printing speed, wherein due to the generally slower operation of the digital printing station, if necessary, a plurality of jet nozzles or a plurality of digital printing stations are provided, which each apply partial images. Via an electronic control, these additional jet nozzles and / or digital printing stations are switched on and, if necessary, the additionally applied print image is divided into partial images.

As the printing medium, not only paint but also a primer, impregnation, adhesive, fibers, flakes and other coatings can be applied. For this purpose, each digital printing station can have different types of nozzles, which can be used alternatively or in combination.

Regarding the method, the invention is characterized in that the at least one digital printing station for printing a workpiece with the workpiece carriers is non-positively and / or positively coupled. The workpiece is additionally printed by at least one digital printing station, which has at least one controllable jet nozzle. According to this method, printing can be performed with the above-described printing machine. This results in the above-described advantages.

A preferred development of the method according to the invention is that a control for the at least a digital printing station is provided, through which the workpieces are individually printed differently. The machine can therefore be used flexibly, but conversions are avoided by the digital printing station.

A high operating speed of the printing press is ensured according to the invention in that a controller for a plurality of digital printing stations is provided which divides a print job among the plurality of digital printing stations according to a predetermined power stroke. The working cycle is determined by the operating speed of the screen printing stations. As a result, the performance of the overall machine remains as in a conventional carousel screen printing machine.

Furthermore, it is preferred that for printing a printing plate, on which the screen printing stations are arranged, is approximated by means of a lifting device relative to the turntable and that for stepwise further conveying the pressure plate is relatively removed from the turntable.

In particular, when applying an individual print image by means of the digital printing station on a dark background, a second, preceding digital printing station is arranged according to the invention, with which a contrasting background color, in particular a white background, is applied according to the subsequent individual imprint. This digital printing station can be preceded or followed by a drying station and / or a smoothing station. A previous smoothing of the substrate ensures better adhesion. A drying station allows a rapid application of the following inks. The invention will be described below with reference to a preferred embodiment, which is shown schematically in the drawings. In the drawings show:

Fig. 1 is a sectional side view of a printing machine according to the invention; and

2 is a schematic plan view of the rotary indexing device according to FIG. 1.

1 shows a printing machine 50, which belongs to the type of carousel screen printing machines. The printing machine 50 comprises, as essential components, a machine bed 12, which is constructed from a central, approximately circular base frame 14 and three machine feet 16 attached thereto, a turntable 20 rotatable relative to the machine bed 12 and a printing plate 40 arranged above it with screen printing stations 42 arranged thereon in a star shape.

Centered in the machine bed 12, a torsionally rigid machine shaft 18 is formed, which extends vertically upwards. To this machine shaft 18, the turntable 20 is arranged, which in the illustrated embodiment has a conical bell 21 with a horizontally arranged base plate 23. Starting from the bottom plate 23, a plurality of rod-shaped struts 33, which support radially arranged rod-shaped arms 32, extend radially outward. At the star-shaped, arranged at the same angular distance arms 32 workpiece carrier 34 are arranged at the outwardly directed free ends, which serve to receive a printed material, such as a T-shirt. Above the workpiece carrier 34, the respectively associated screen printing stations 42 are attached to the printing plate 40. In the present embodiment, the screen printing stations 42 are formed as identically constructed modules with a screen corresponding to the desired print image, an inking member and a squeegee device for spreading the ink on the screen for transferring the ink to the print material. The pressure plate 40 is rotatably connected via a connecting hub 44 with a Hubschaft 46. The stroke shaft 46 directed coaxially with the machine shaft 18 is axially displaceable relative to the machine bed 12 by means of a lifting device, not shown, in particular a hydraulic cylinder. In a known manner, the printing plate 40 is lowered with the screen printing stations 42 to the arranged on the workpiece carriers 34 print material so to carry out a printing operation, so that the desired print image can be transmitted. After completion of the printing step, the printing plate 40 is moved vertically upwards with the screen printing stations 42, so that the screen printing stations 42 are spaced from the workpiece carriers 34. Then, a further rotation of the turntable 20 by a clock step with a predetermined rotation angle, so that then again by lowering the pressure plate, a further printing step can be performed.

For driving the turntable 20, a rotary indexing device 10 is provided in an annular recess of the machine bed 12. In this case, the bottom plate 23 of the turntable 20 is attached directly to a disk-shaped rotor 28 of an electric motor. Corresponding to the rotor 28, an annular stator 26 with the electrical windings and the corresponding power supply is arranged on the machine bed 12. The rotor 28 and the stator 26 form bil the one electric drive 24 of the rotary indexing device 10. Instead of this direct drive other types of drives can be used.

According to the schematic representation of FIG. 2, the printing press 50 has a total of ten screen-printing stations 42 arranged in a star shape relative to the rotation axis 22, which are fastened along the circumference of the pressure plate 40. Rotatable about the axis of rotation 22 a total of ten star-shaped arranged workpiece carrier 34 are arranged.

At an input E, the workpieces are clamped on the workpiece carriers 34. By stepwise rotation in a clockwise direction, the workpiece passes through the individual screen printing stations 42, in each of which an imprint can be made. After the tenth screen printing station 42, two digital printing stations 60 are arranged, which are mounted directly on the floor separately from the machine bed. The position of the digital printing stations 60 is centered corresponding to the axis of rotation 22, so that the workpieces to be printed with the workpiece carriers 34 centered under the digital printing stations 60 can be moved. In this way, for example, an individual order, a running number or a name can be printed according to an individual tax specification. Finally, the workpiece is rotated to the output A, in which the printed workpiece can be removed. Optionally, one or more drying stations could be arranged along the circumference of the machine, which would correspondingly reduce the number of printing stations.

Claims

1. Printing machine for printing on workpieces, especially textiles, with

a machine bed (12),

a plurality of screen printing stations (42) arranged on the machine bed (12),

- A turntable (20) having a plurality of workpiece carriers (34) and on the machine bed (12) mounted about an axis of rotation (22) and for the stepwise conveyance of the workpieces to the screen printing stations (42) is driven, and

- At least one digital printing station (60) with at least one controllable jet nozzle for additional printing of the workpieces. This means that the at least one digital printing station (60) can be positively and / or positively coupled to the printing of a workpiece with its workpiece carrier (34).

2. Printing machine according to claim 1, characterized in that the screen printing stations (42) are arranged together on a pressure plate (40) which is mounted on the machine bed (12), and in that a lifting device is provided for axially displacing the printing plate (40) with the screen printing stations (42) relative to the turntable (20), the printing plate (40) approximating the turntable (20) for printing and removing the turntable (20) step by step becomes.

3. Printing machine according to claim 2, characterized in that the at least one digital printing station (60) is mounted separately from the printing plate (40) with the screen printing stations (42).

4. Printing machine according to claim 2 or 3, characterized in that the pressure plate (40) above the turntable (20) with the machine bed (12) is connected and that the at least one digital printing station (60) below the turntable (60) with the Machine bed (12) connected or stored separately from the machine bed (12) directly on the ground.

5. Printing machine according to one of claims 1 to 4, characterized gekennzeic h'n et, that the workpiece carrier (34) and / or the workpiece with a mark is providable and that the at least one digital printing station (60) has a sensor for detecting the mark and an adjusting device, with which the at least one jet nozzle is adjustable.

6. Printing machine according to one of claims 1 to 5, characterized in that for adjusting the printing performance, the at least one jet nozzle is height adjustable relative to the workpiece.

7. Printing machine according to one of claims 1 to 6, characterized in that the power stroke of the screen printing stations (42) and the at least one digital printing station (60) is the same, in particular between 0.5 to 5 seconds, preferably between 1 to 2 seconds ,

8. A method for printing on workpieces, in particular textiles, wherein

- The workpieces are clamped on workpiece carriers (34) which are arranged on a turntable (20) which is rotatably mounted about a machine bed (12),

- The workpieces are conveyed by stepwise driving the turntable (20) to working positions at which the workpieces are each printed by a screen printing station (42), and

- The workpieces are additionally printed by at least one digital printing station (60) which has at least one controllable jet nozzle, characterized in that the at least one digital printing station (60) for printing a workpiece with the workpiece carrier (34) force and / or positively coupled.

9. The method according to claim 8, characterized in that a control for the at least one digital printing station (60) is provided by which the workpieces are individually printed differently.

10. The method according to claim 8 or 9, characterized in that a control for a plurality of digital printing stations (60) is provided, which according to a predetermined power stroke, a print job among the plurality of digital printing stations (60).

11. The method according to any one of claims 8 to 10, characterized in that for printing a printing plate (40) on which the screen printing stations (42) are arranged, by means of a lifting device is approximated relative to the turntable (20) and that to the gradual Weiterfördern the pressure plate (40) is relatively removed from the turntable (20),