Winding Device for Winding a Substantially Insulating Web Material

Abstract

A winding device for a substantially electrically insulating web material having a winding roller on which the web material can be wound, characterized in that an apparatus exists for transferring an electric charge to the web material on the winding roller, and/or when deflecting to the winding roller, and the apparatus for transferring an electric charge is connected to at least one electrical high-voltage source with a positive or negative polarity.

Claims

1. A winding device for a substantially electrically insulating web material having a winding roller on which the web material can be wound, characterized in that an apparatus exists for transferring an electric charge to the web material on the winding roller, and/or when deflecting to the winding roller, and the apparatus for transferring an electric charge is connected to at least one electrical high-voltage source with a positive or negative polarity.

2. The winding device according to claim 1 that has an impression roller which lies against the web material on the circumference of the winding roller in order to roll against it in the direction opposite that of the winding roller, wherein the impression roller has an electrically (semi-) conductive layer on the circumference, an apparatus exists for transferring an electric charge to the electrically (semi-) conductive layer of the impression roller, and the apparatus for transferring an electric charge to the (semi-) conductive layer is connected to the electrical high-voltage source.

3. The winding device according to claim 1, wherein the apparatus for transferring an electric charge to the web material is a charging electrode that is connected to the electrical high-voltage source.

4. The winding device according to claim 1, wherein the apparatus for transferring an electric charge to the web material is at least one brush, one flexible tab consisting of electrically conductive material or another direct charging apparatus that is connected to the electrical high-voltage source.

5. The winding device according to claim 1, wherein the apparatus for transferring an electric charge to the web material is an idler roller that is connected to the electrical high-voltage source.

6. The winding device according to claim 1 which has an idler roller that is arranged at a distance from the winding roller which has a rotary axis that is arranged parallel to the rotary axis of the idler roller so that the web material is guided by the idler roller to the circumference of the impression roller, deflected by the impression roller, and guided on the circumference of the winding roller.

7. The winding device according to claim 1, wherein the apparatus for transferring an electric charge to the web material is connected by a switching apparatus to a high-voltage source with a positive polarity, and a high-voltage source with negative polarity.

8. The winding device according to claim 1, wherein the high-voltage source supplies an adjustable high voltage.

9. The winding device according to claim 1, wherein at least one field strength measuring device is arranged so that it detects the web material on the winding roller and/or while being deflected to the winding roller, wherein the field strength measuring device measures the charge that the web material has and is connected to at least one control apparatus that is connected to the high-voltage source and/or the switching apparatus in order to apply a high-voltage of a specific level and/or polarity, depending on the charge of the web material measured by the field strength measuring device, to the impression roller.

10. The winding device according to claim 1, wherein the control apparatus is designed so that it applies a high-voltage at a level and/or polarity to the impression roller which causes a minimum charging of the web material wound on the winding roller.

11. The winding device according to claim 1 that is an alternating winding roller device.

12. The winding device according to claim 1 that is a winding device of a rotary printing press.

13. The winding device according to claim 1 that is a winding device of a reel slitter.

14. The winding device according to claim 1 that is a winding device of a film extrusion machine.

15. The winding device according to claim 1 that is a winding device of a laminator.

Description

[0041] The invention will be further explained with reference to the accompanying drawings of exemplary embodiments. In the drawings:

[0042] FIG. 1 shows a highly schematic view of a rotary printing press with a plurality of print units and high-voltage sources with different polarities switchably assigned thereto;

[0043] FIG. 2 shows a highly schematic view of high-voltage generators with different polarities having switching apparatuses and pressure rollers with different charging systems;

[0044] FIG. 3 shows a highly schematic view of an alternative rotary printing press;

[0045] FIG. 4 shows a highly schematic view of a winding device according to the invention with an impression roller with a top loading system;

[0046] FIG. 5 shows an alternative winding device according to the invention with a winding roller with a core charging system.

[0047] In the following explanation of different exemplary embodiments, correspondingly designated components are provided with the same reference numbers.

[0048] FIGS. 1 to 3 are exemplary embodiments of rotary printing presses with electrostatic assists that can be retrofitted with the winding device according to the invention. FIGS. 1 to 3 do not describe the invention but rather are only for better understanding the technical background of the invention.

[0049] According to FIG. 1, a rotary printing press has four sequentially arranged print units 1.1 to 1.4. Each print unit 1.1 to 1.4 has a metal, electrically conductive impression cylinder 2.1 to 2.4 that is electrically grounded by electrically conductive bearings. Moreover, each print unit 1.1 to 1.4 has an electrostatic assist 3.1 to 3.4.

[0050] Each electrostatic assist 3.1 to 3.4 has a pressure roller 4.1 to 4.4 which is a counter-pressure cylinder that rolls on the impression cylinder 2.1 to 2.4. Moreover, each electrostatic assist 3.1 to 3.4 has a high-voltage source with a positive polarity 5.1 to 5.4 and a high-voltage source with a negative polarity 6.1 to 6.4. The high voltage of each high-voltage source 5.1 to 5.4 and 6.1 to 6.4 is preferably adjustable.

[0051] Each print unit 1.1 to 1.4 comprises a switching apparatus 7.1 to 7.4, wherein each switching apparatus 7.1 to 7.4 is connected to a high-voltage source with a positive polarity 5.1 to 5.4 and a high-voltage source with a negative polarity 6.1 to 6.4.

[0052] Each switching apparatus 7.1 to 7.4 is connected via an apparatus for transferring an electric charge 8.1 to 8.4 to a (semi-) conductive layer of the pressure roller 4.1 to 4.4 of the same print unit 1.1 to 1.4. Each pressure roller 4.1 to 4.4 together with the apparatus for transferring an electric charge 8.1 to 8.4 forms an apparatus for generating an electrical field 9.1 to 9.4 in the printing nip 10.1 to 10.4 between the impression cylinder 2.1 to 2.4 and pressure roller 4.1 to 4.4.

[0053] From an unwinding roller 11, a printing substrate 12 is guided between the impression cylinders 2.1 to 2.4 and pressure rollers 4.1 to 4.4 of sequential print units 1.1 to 1.4. Between each print unit 1.1 to 1.4 are idler rollers and/or compensation rollers 13.1 to 13.4 and 14.1 to 14.4 by means of which the printing substrate 12 is carried away. After the print units 1.1 to 1.4, the printing substrate 12 is guided to a winding roller 15.

[0054] A field strength sensor 16 is arranged next to the printing substrate 12 directly before it is wound on the winding roller 15.

[0055] Moreover, another field strength sensor 17.1 to 17.4 is arranged after each print unit and is assigned to the printing substrate 12 on an idler roller 14.1 to 14.4.

[0056] Each print unit 1.1 to 1.4 has a control apparatus 18.1 to 18.4 for controlling the electrostatic assist 3.1 to 3.4. The control apparatuses 1.1 to 1.4 are connected to each other by a data bus 19.

[0057] Moreover the control apparatuses 18.1 to 18.4 are connected by the data bus 19 to a main control 18.5.

[0058] The field strength sensor 16 is connected by the data bus 19 to the control apparatuses 18.1 to 18.5.

[0059] Each additional field strength sensor 17.1 to 17.4 is connected to the control apparatus 18.1 to 18.4 of the same print unit 1.1 to 1.4 and/or to the data bus 19.

[0060] When the rotary printing press is operating, the printing substrate 12 is wound off of the unwinding roller 11, guided through the print units 1.1 to 1.4 and wound onto the winding roller 15. It is printed with various inks in the print units 1.1 to 1.4.

[0061] The switching apparatuses 7.1 to 7.4 are controlled by the control apparatuses 18.1 to 18.4 so that a high voltage with a positive polarity is applied to the last used print unit 1.4 in the throughput direction. The polarities of the high-voltages supplied to the print units 1.1 to 1.3 used upstream in the direction of throughput are adjusted by the control apparatuses 18.1 to 18.4 so that the field strength sensor 16 measures a minimum charge of the printing substrate 12 before the winding roller 15. For this purpose, for example, the print units 1.1 and 1.3 are supplied with high voltages with a negative polarity, and the print unit 1.2 is supplied with a high voltage with a positive polarity.

[0062] According to FIG. 2 the apparatus for transferring an electric charge 8.1 to 8.4 to the (semi-) conductive layer of the pressure roller 4.1 to 4.4 can be designed differently. All of the designs have a pressure roller 4.1 to 4.4 with a metal core 20. With the designs in FIG. 2a to c, the core has a rotating shaft 21 which is borne in roller bearings 22.1, 22.2. With the designs in FIGS. 2a and b, the roller bearings 22.1, 22.2 are grounded. With the design according to FIG. 2c, the roller bearings 22.1, 22.2 are separated from the ground by insulations.

[0063] With the designs in FIG. 2d to f, the metal core 20 is borne by roller bearings 22.1, 22.2 on a fixed shaft 24. The shaft 24 is held in insulation elements 23.1, 23.2 and insulated from ground.

[0064] With the design in FIG. 2a, an insulating layer 25 is arranged on the outside of the outer circumference of the metal core 20. A (semi-) conductive layer 26 of the pressure roller 4.1 to 4.4 is seated directly on the outside of the insulating layer 25.

[0065] With the design in FIG. 2b, an insulating layer 25 is arranged on the outer circumference of the metal core 20, an electrically highly-conductive layer 27 is arranged on the outer circumference of the insulating layer 25, and the (semi-) conductive layer 26 of the pressure roller 4.1 to 4.4 is seated on the outer circumference of said highly-conductive layer. With the design in FIG. 2f, an electrically highly-conductive layer 27 is arranged on the outer circumference of the metal core 20, and the (semi-) conductive layer 26 of the pressure roller 4.1 to 4.4 is seated on the outer circumference of the highly-conductive layer 27.

[0066] With the design in FIG. 2a, the electric charge is supplied by a needle electrode 28 from the outside to the layer 26 of the pressure roller 4.1 to 4.4 (top loading). The insulating layer 25 prevents the charge from flowing to ground.

[0067] In FIG. 2b, the charge is supplied via the one charging electrode 29 to an end face of the pressure roller 4.1 to 4.4 to the electrically highly-conductive layer 27 (side loading), and is evenly distributed from there over the inside of the layer 26. The insulating layer 25 prevents a discharge to ground here as well.

[0068] In FIG. 2c, the high voltage is supplied via the shaft 21 (core charge loading), for example by means of a fluid transfer system 30 according to EP 1 780 011 B1, or by means of brushes. By means of the metal core 20, the charge is evenly distributed to the inside of the layer 26. The insulation elements 23.1, 23.2 prevent a discharge to ground.

[0069] With the design in FIG. 2d, the charge is supplied by the fixed shaft 24 and the roller bearings 22.1, 22.2 to the metal core 20 (core charge loading). The charge is distributed evenly to the layer 26 over the outer circumference. Here as well, the insulation elements 23.1, 23.2 prevent discharge of the charge to ground.

[0070] In FIG. 2e, the charge of the layer 26 is in turn supplied by a needle electrode 28 (top loading). In this case, the insulation elements 23.1, 23.2 prevent a discharge to ground.

[0071] According to FIG. 2f, the charge in turn is supplied by a charging electrode 29 to an end face of the highly-conductive layer 27 (side loading). In this case the insulation elements 23.1, 23.2 prevent the charge from draining to ground. In this design, one of the insulations can be dispensed with.

[0072] According to FIG. 1, the pressure roller 4.1 to 4.4 and the apparatus for transferring the electric charge 8.1 to 8.4 are designed like in FIG. 2c or d.

[0073] The rotary printing press in FIG. 3 differs from the one in FIG. 1 in that the pressure rollers 4.1 to 4.4 and the apparatuses for transferring the electric charge 8.1 to 8.4 are designed as in FIG. 2a or 2e.

[0074] According to FIG. 4, a winding device according to the invention has an idler roller 30 by means of which the web material (printing substrate) 12 is deflected to an impression roller 31. The web material 12 is fed to a winding roller 15 by the impression roller 31.

[0075] On the circumference, the impression roller 31 has an insulation layer 32, as well as a (semi-) conductive layer 33 on the circumference of the insulation layer 32. The impression roller 31 is hence designed like the pressure roller in FIG. 2a.

[0076] A charging electrode 28 which, for example, is designed as a needle electrode is arranged at a distance from the impression roller 31 parallel to its rotary axis. The charging electrode 28 is connected by an electric line and a switching apparatus to a positive and negative high-voltage generator.

[0077] The web material 12 is fed to the winding roller 15 by the idler roller 30 and the impression roller 31. The impression roller 31 presses the web material 12 against the winding roller 15. In so doing, the (semi-) conductive layer 33 of the impression roller 31 is charged by the charging electrode 28 so that existing charges in the web material 12 are compensated, or respectively the web material 12 is discharged. Consequently, the web material 12 can be wound onto the winding roller 15 without undesirable charges.

[0078] The exemplary embodiment in FIG. 5 differs from the above-described in that the impression roller 31 has an electrically conductive core 34 and a (semi-) conductive layer 33 on the circumference. An electric charge is supplied to the core 34 by a core charging system. By means of this measure, charges in the web material 12 are compensated, or respectively discharged, and consequently the web material on the winding roller 15 does not contain any undesirable charges.