CN-121988472-A - Dispensing device

Abstract

An apparatus for spreading sheets with powder in a printing press comprises a powder nozzle (8) and a supporting air nozzle (10, 11). Beside the respective powder nozzle (8), two associated support air nozzles (10, 11) are arranged on connecting centerlines (14, 15) which connect the center point (M) of the respective powder nozzle (8) with the center points (M) of two adjacent powder nozzles (8).

Inventors

• C. Haas

Assignees

• 海德堡印刷机械股份公司

Dates

Publication Date

20260508

Application Date

20250928

Priority Date

20241108

Claims (6)

1. 1. Device for spreading sheets (2) with powder (5) in a printing machine, comprising powder nozzles (8) and supporting air nozzles (10, 11), characterized in that, beside the respective powder nozzle (8), two associated supporting air nozzles (10, 11) are arranged on connection centerlines (14, 15) connecting the midpoint (M) of the respective powder nozzle (8) with the midpoint (M) of two adjacent powder nozzles (8).
2. 2. The device according to claim 1, characterized in that the supporting air nozzle (10, 11) has an elongated air outlet face (a).
3. 3. The device according to claim 2, characterized in that the air outlet face (a) is rectangular.
4. 4. The device according to claim 2, wherein the air outlet face (a) is arcuate.
5. 5. The device according to claim 1 or 2, characterized in that the connecting centerlines (14, 15) together form a straight alignment line (16) on which the midpoint (M) of the powder nozzle (8) is located.
6. 6. Device according to claim 1 or 2, characterized in that the powder air jet (9) of the respective powder nozzle (8) and the support air jets (12, 13) of the two associated support air nozzles (10, 11) penetrate each other before the powder air jet (9) and the support air jets (12, 13) impinge on the sheet (2).

Description

Dispensing device Technical Field The invention relates to a device for spreading sheets with powder in a printing press, comprising a powder nozzle and a supporting air nozzle. Background Such devices are used to prevent sheets from sticking to each other in the stack. One such device is described, for example, in DE102008049547B 4. Disclosure of Invention The object of the present invention is to provide a further dispensing device. This object is achieved by a device for spreading sheets with powder in a printing press, comprising powder nozzles and supporting air nozzles, characterized in that, beside the respective powder nozzle, two supporting air nozzles are arranged on connection centerlines connecting the midpoint of the respective powder nozzle with the midpoint of the adjacent powder nozzle. An advantage of the device according to the invention is that with it a streak-free powder application can be ensured. Another additional advantage is that a uniform powder distribution can be achieved at all printing speeds. The following are possible extensions: the support air nozzle may have an elongated air outlet opening. The air outlet opening may be rectangular. The air outlet opening may be arcuate. The connecting centerlines may together form a straight alignment line on which the midpoint of the powder nozzle is located. The powder air jet of the respective powder nozzle and the supporting air jet of the two associated supporting air nozzles can penetrate each other before the powder air jet and the supporting air jet impinge on the sheet. Drawings An extension will also be made from the following description of the embodiments and the related drawings. The drawings are as follows. Fig. 1 shows a schematic view of a printing press with a spreading device in a side view. FIG. 2 shows a detailed view of the dispensing device in front view. FIG. 3 shows a detailed view of the dispensing device in a top view. FIG. 4 is a modified embodiment of the dispensing device. Detailed Description The sheet offset printing press shown in partial view in fig. 1 comprises a sheet delivery device with a conveyor 1, which conveys and deposits sheets 2 (see fig. 2) freshly printed with ink and/or varnish in sequence through a spreading device 3 onto a sheet stack 4. In the process, the sheets 2 are sprayed with powder 5 by the spreading device 3, which prevents the sheets 2 from sticking to each other in the delivery stack 4. The transport device 1 has gripper bars fixed on an endless transport chain, which gripper bars hold a sheet 2 (which is not shown in fig. 1 for simplicity) transported in a transport direction 6. Also not shown in fig. 1 is a sheet guide 7 (see fig. 2), which sheet Zhang Daoban guides the sheet 2 being conveyed in the region of the spreading device 3. Fig. 2 shows a spreading device 3 with a row of evenly distributed nozzle groups, seen in the conveying direction 6. Each nozzle group comprises a powder nozzle 8 which emits a powder air jet 9 consisting of blowing air and the powder 5 mixed therein (see fig. 1). Furthermore, each nozzle group comprises two support air nozzles 10, 11, separated from each other, which respectively emit support air jets 12, 13, which are composed of powder-free blowing air. The powder nozzle 8 is arranged between two supporting air nozzles 10, 11 assigned to it. In fig. 2, the powder air jet 9 and the support air jets 12, 13 are symbolically indicated by arrows only for simplicity. In practice, however, the powder air jet 9 and the supporting air jets 12, 13 expand towards the sheet 2 to be dusted. In fig. 3, the dispensing device 3 is shown in a viewing direction III (see fig. 2). An imaginary connecting center line 14, 15 extends between the center point M of the respective powder nozzle 8 and the center point M of the adjacent powder nozzle 8. The two supporting air nozzles 10, 11 of each nozzle group are arranged in such a way that their nozzle opening surfaces or air outlet surfaces a are cut by connecting centerlines 14, 15. In the example shown, the connecting centerlines 14, 15 cut exactly from the middle the air outlet face a of the supporting air nozzle 10, 11. It is however also possible to cut off the air outlet face a supporting the air nozzles 10, 11 eccentrically with respect to the connecting centre lines 14, 15, wherein the middle point of the air outlet face a is slightly offset with respect to the connecting centre lines 14, 15. The connecting centerlines 14, 15 of the powder nozzles 8 together form a straight alignment line 16 on which the powder nozzles 8 are arranged with a uniform midpoint spacing V. The air outlet face a is elongate and has a length S and a width B, where B < S. The powder nozzles 8 each have a circular nozzle opening surface with a diameter D, wherein B < D and S < D. The size of the air outlet face a of each supporting air nozzle 10, 11 is smaller than the size of the nozzle opening face of the powder nozzle 8, wherein for