GB2307470A

GB2307470A - Sheet braking delivery device

Info

Publication number: GB2307470A
Application number: GB9623885A
Authority: GB
Inventors: Juergen Wenzel
Original assignee: MAN Roland Druckmaschinen AG
Current assignee: Manroland AG
Priority date: 1995-11-25
Filing date: 1996-11-15
Publication date: 1997-05-28
Anticipated expiration: 2016-11-15
Also published as: FR2741610B1; FR2741610A1; DE19543963C1; JP2866065B2; JPH09175705A; GB9623885D0; GB2307470B

Description

2307470 1 - SHEET DELIVERY DEVICE FOR A PRINTING PRESS This invention

relates to a sheet delivery device in the delivery of a printing press, having a device for braking and stretching sheets to be deposited on to a delivery pile.

A device of this type is known from DE 2 811 963 C2. A pneumatically acting sheet brake device is arranged transverse to the sheet feeding direction in front of the delivery pile on a carrier shaft. On the carrier shaft are fixed several rotating braking rollers which can be provided with suction air and which can be removed and replaced, which have a separate drive.

It is disadvantageous with this device that the sheets to be braked as a result of the line contact at the periphery of the rotating braking roller effect an insufficient deceleration of the respective sheet to be deposited, particularly at higher delivery rates. Depending upon the curvature of the braking rollers, the rear region of the sheet between braking roller and delivery pile is fed undefined over a longer path.

- 2 A sheet braking device with a rotating suction belt in the delivery is known, for example, from DD 288 565 As. The suction belts improve the surface guiding of the sheet, but slip phenomena as well as an extension phenomena arise in the suction belt. These disadvantages lead to premature wear of the suction belts, which often have to be changed.

is It is the object of the invention to create a sheet delivery device which has a perceptibly improved braking action which guides the rear region of the sheet over a longer path towards the delivery pile.

According to the present invention, there is provided a sheet delivery device for braking and stretching sheets to be deposited below a chain conveyor arranged transversely to the sheet running direction prior to a delivery pile, wherein the device comprises at least two contra-rotating drivable sheet braking units arranged symmetrically relative to the centre of the delivery, each sheet braking unit substantially having the shape of a truncated cone, the braking conical surface of which has openings which are linked with radial conduits to a channel arranged in a fixed axle and to a source of suction.

Transversely to the feed direction of the sheet, there are arranged rotatably drivable sheet brake units which can be subjected pneumatically to suction. The sheet braking units rotate in this connection not about a horizontal axis, but about an axis inclined at a defined angle to the vertical. A sheet braking unit has essentially the shape of a truncated cone, brakes with its conical surface the sheets fed by the circulating feed system to the delivery pile with closed grippers and in particular stretches the rear part of the sheet by its rotary movement.

It is the advantage of the invention that a large surface sheet guidance, and thereby a defined braking of the sheets with little maintenance outlay, is achievable. The sheet braking unit in a device in accordance with the invention is suited for all types of material to be printed and simultaneously has the advantage that the sheet end is stretched and possible rolling up or fluttering of the sheet end is counteracted. This is achieved by separating the sheet braking units either side of a notional centre line of the delivery and running in the feed direction. The at least two sheet braking units are driven contra-rotating. If several sheet braking units are used, then, with respect to the centre line of the delivery, the sheet braking units arranged on one side are all contra-rotating with respect to the sheet braking units arranged on the other side of the centre line.

The invention is illustrated further, by way of example, with reference to an exemplary embodiment shown in the accompanying drawings, in which:

Figure 1 shows a sheet braking unit in plan view, Figure 2 a sheet braking unit in the sheet running direction (front view), Figure 3 a sheet braking unit in side view, Figure 4 a sheet delivery Figure 5 a plan view on four sheet braking units.

In Figure 4, a sheet delivery 1 of a rotary printing press is illustrated which has circulating chain conveyors 4. The chain conveyors are linked by gripper systems 3 which remove the sheets 2 from an earlier arranged printing unit or a varnishing unit and feed them in the direction of sheet running 9 to a delivery path 5. The sheets 2 are in this connection transported from the gripper system 3 via guide units 8 subjected pneumatically to blowing or suction air. Above the delivery pile 5 a blowing air device 6 is arranged which backs up the deposition of the arriving sheet 2 from the plane of the chain conveyor 4 in the region towards the delivery pile 5. Arranged below the fed sheet 2 transverse to the sheet running direction 9 is the device for braking and stretching sheet 2 to be deposited. The device consists in the present example of four sheet braking units 7, arranged as in Figure 5. A sheet braking unit 7 is formed essentially by a straight truncated cone, the conical surface 13 of which serves for braking the sheet 2. The conical surface 13 has openings 19 which are preferably constructed as bores. The openings 19 are arranged distributed over the entire conical surface 13 and have respective conduits 20 which are arranged in the truncated cone radially relative to an axis 15. Arranged in the fixed axis 15 is a channel 21 which is linked with the conduits 20 as well as openings 19 and preferably with an external source of suction. In this connection, the channel 21 subjects the openings 19 and conduits 20 of the circular surface 13 to suction. The axis 15 is arranged inclined transverse to the sheet running direction 9 at an angle a to the vertical 17. Thereby only a part of the conical surface is - 13 comes into contact with sheet 2. This part corresponds to the circular sector for subjection to suction and constitutes the braking region 22 which is determined by a suction length 11 and a suction width 18. In particular, on delivering sheets to printed recto and verso, the suction width 18 is constructed narrowly. The sheet braking devices 7 are shiftable on at least one cross-member transversely to the sheet running direction 9 to the print free places.

In a further development, the axis 15 is additionally inclined in the sheet running direction 9 at an angle to the vertical 17 in the direction towards the delivery pile 5. Thereby the rear end of the sheet is more favourably lowered on to the delivery pile 5.

Taken on the delivery centre 4 in the plan view according to Figure 5 in the first (left hand) half two sheet braking units 7 are arranged which both rotate in the same sense in direction of rotation 10 (counterclockwise). In the second (right) halves, two further sheet braking devices 7 are arranged, which both rotate in the same sense in the direction of rotation 16 (clockwise). Thereby all sheet braking units 7 rotate from the centre of the delivery 14 outwardly in the direction towards the side frames. The sheet braking unit 7 has a drive 12 which can be constructed as an individual drive or as an overall drive for all sheet braking units. The drive 12 engages in the present example below the conical surface 13.

The mode of operation is as follows: Sheets 2 are fed to the delivery pile 5 by the gripper system 3 and deposited there. During the transport, each sheet 2 is guided with its rear region over the sheet braking device 7. Thereby, it is sucked against the openings 19 of the conical surface 13and stretched by the rotary movement. After opening of the gripper system 3, the sheet 2 is braked in its speed and fed to the front edge stop of the delivery pile. The rotary movement of the sheet braking units 7 supports thereby the sheet 2 from its transport path up to the delivery pile 5. By means of the free selection of pneumatically actuatable circular sectors of a sheet braking unit 7, the suction link 11 can be constructed in such a way that the distance between delivery pile 5 and braking region 22 is very small.

Claims

1. A sheet delivery device for a printing press including a device for braking and stretching sheets to be deposited below a chain conveyor arranged transversely to the sheet running direction prior to a delivery pile, wherein the device comprises at least two contra-rotating drivable sheet braking units arranged symmetrically relative to the centre of the delivery, each sheet braking unit substantially having the shape of a truncated cone, the braking conical surface of which has openings which are linked with radial conduits to a channel arranged in a fixed axle and to a source of suction.

2. A sheet delivery device according to Claim 1 wherein the openings can be subjected to suction over a defined circular sector of the conical surface via the channel and conduits.

3. A sheet delivery device according to Claim 1 wherein the axle is inclined at an angle to the vertical transverse to the sheet running direction.

4. A sheet delivery device according to any one of Claims 1 to 3 wherein the axis is inclined at an angle to the vertical in the sheet running direction towards the delivery pile.

5. A sheet delivery device according to any one of Claims 1 to 4 wherein the sheet braking unit has the shape of a right truncated cone.

6. A sheet delivery device according to Claim 1, 8 - characterised in that the conical surface of the sheet braking unit is arranged rotating about the axle.

7. A sheet delivery device according to any one of Claims 1 to 6 and including several sheet braking devices arranged transversely to the sheet running direction and located either side of the centre line of the delivery, those rotating on each side of the delivery centre rotating in the same direction of rotation, and counter to the direction of rotation of those on the other side of the centre line.

8. A sheet delivery device including a sheet braking arrangement substantially as hereinbefore described with reference to the accompanying drawings.