GB2037259A

GB2037259A - Apparatus for depositing sheets

Info

Publication number: GB2037259A
Application number: GB7938700A
Authority: GB
Original assignee: Polygraph Leipzig Kombinat Veb
Current assignee: Polygraph Leipzig Kombinat Veb
Priority date: 1978-11-08
Filing date: 1979-11-08
Publication date: 1980-07-09
Also published as: GB2037259B; DE2944227A1; SE7909176L; SU1060551A1; DD140135A1

Abstract

An apparatus for depositing sheets (14) comprises a sheet depositing station (1,3), at least one suction roller (12.1, 12.2) to engage a sheet (14) being advanced horizontally towards the sheet deposit station (1,3), blower means (7) to blow such sheet (14) facially onto the deposit station (1,3), and suction means (10) disposed at lateral regions of upstream portions of the deposit station (1,3) for sucking air from the region of the deposit station (1,3) to aid deposit of such sheet (14) at the deposit station (1,3). <IMAGE>

Description

SPECIFICATION Apparatus for depositing sheets The present invention relates to an apparatus for depositing sheets at for example a flyer sheet deliverer of a processing machine such as a printing machine.

In sheet processing machines, for example printing machines, the sheets are, after printing, conveyed in the flyer sheet deliverer by means of grippers over a deposit stack, freed and deposited.

With increasing machine performance and with large formats, stack formation is made difficult by air cushions forming between the stack and the sheet.

An apparatus for the accelerated deposit of sheets on a deposited stack is disclosed in DD-PS 111 870, in which a sheet is acted on by a blast of air directed normal to the plane of the sheet after a gripper gripping the sheet has opened. The blast of air is so controlled that the sheet is acted on outwardly from inside and the air cushion so to speak wiped out.

It is a disadvantage of this apparatus that the trailing edge of a sheet in consequence of overlapping by the succeeding sheet is only influenced by the blast of air for a short time, whereby the time taken for the sheet to drop is longer than the period of the blast of air. The slow falling motion of the rear portion of a sheet from the plane of the path in which it is advanced prior to being deposited can at high speeds cause adhesion of the rear edge of the falling sheet to the succeeding sheet being guided by the gripper over the deposited stack. This may lead to rolling-over in the stack and thereby to inexact stack formation.

US-PS 2645480 discloses an apparatus in which suction devices are disposed at the side edge in addition to the means for providing a blast of air from above. The suction devices enhance the wiping-out effect attained by the means for providing a blast of air while the control of the suction device takes place in the same manner as the means for providing a blast of air above the sheet guidance path.

It is a disadvantage of this apparatus that the rear edge is not sufficiently influenced in the case of large formats so that the possibility of the rear sheet edge touching the following sheet is not completely excluded.

According to the present invention, there is provided an apparatus for depositing sheets comprising a sheet depositing station, at least one suction roller to engage a sheet being advanced horizontally towards the sheet deposit station, blower means to blow such sheet facially onto the deposit station, and suction means disposed at lateral regions of upstream portions of the deposit station for sucking air from the region of the deposit station to accelerate deposit of such sheets at the deposit station.

Embodiments of the present invention will now be more particularly described by way of example and with reference to the accompanying drawings in which Figure 1 shows a side elevation of a flyer sheet deliverer, Figure 2 shows a plan view onto a deposited stack of sheets, and Figure 3 shows an arrangement of suction elements relative to a suction roller.

Figure 1 shows a side elevation of a flyer sheet deliverer comprising a chain circle 4 provided with a gripper carriage 5 and a deposit stack 1, at which front and rear sheet stops 2 and 3 are arranged. The chain circle 4 is guided over a front chain deflection wheel 6. Several longitudinally extending blast tubes 7 disposed beside one another with nozzles 8 pointing towards the stack 1 are arranged over the stack 1 and above the sheet conveying path.

At the rear edge of the stack 1 in the region of both the lateral edges, suction elements 10 having a suction opening 11 are fastened to a crossbeam 9 and are pivotable towards and away from their operating position. The suction opening faces the stack 1, is provided witha gauze member 13 and is preferably disposed immediately above the upper stack edge. A suction roller 12 comprising a suction roller shaft 12.1 and a suction roller ring 12.2 displaceable on the suction roller shaft 12.1, is arranged in front of the suction elements 10 seen in the sheet conveying direction. As Figure 1 shows, the suction elements 10 are disposed between the suction roller rings 12.2 and underneath the suction roller shaft 12.1.It is, however, possible (Figure 3) to arrange the suction elements 10 underneath the suction roller rings 12.2 so that the suction roller rings can be displaced into any desired position.

The blast tubes 7, suction elements 10 and suction rollers 12 are connected to air supply equipment.

A sheet 14 is conveyed by the gripper carriage 5 over the stack 1 and then freed and deposited on the stack 1. During its conveyance over the stack 1, the sheet 14 is sucked and tautened by the suction roller rings 12.2. After opening of the grippers of the gripper carriage 5, the sheet is acted on from above by the air blast issuing out of the nozzles 8 of the longitudinal blast tubes 7 so that the sheet 14 under the influence of the air blast is pressed onto the stack 1 outwardly from inside while wiping out the air cushion.

Simultaneously, an underpressure is produced in the suction elements 10 and the air under the sheet 14 disposed in the rear region at the side edges of the stack 1 is sucked away so that the sheet 14 also in the rear region afterjumping-offfrom the suction roller rings 12.2 moves rapidly towards the stack 1.

In order to avoid adhesion of the failling sheet 14 at the suction element 10 and to thereby close the suction opening 11, the suction air is controlled cyclically.

The suction air is switched on when the preceding sheet 14 is a component of the stack 1; it is switched off when the rear edge of the sheet 14 to be deposited has largely passed the suction opening 11 of the suction elements 10. The wire gauze member 13 at the suction opening 11 prevents parts of the sheet 14 from being drawn into the suction element 10.

On displacement of the suction roller rings 12.2 on the suction roller shaft 12.1, the suction elements 10 shown in Figure 1 are pivoted away around the crossbeam 9 or as the suction roller rings 12.2 can be displaced as desired over the suction elements (Figure 3).

The above described embodiments have the advantage that above all the side regions of the rear edge, which are insufficiently influenced by the longitudinally extending blast tubes in consequence of the overlapping by the succeeding sheet, are after jumping-off from the suction roller rings moved rapidly out of the sheet path in the direction of the stack so that the rolling-over of this sheet region in consequence of the adhesion to the succeeding sheet is avoided.

The combination of the longitudinally extending blast tubes with the suction elements makes it possible for the suction elements to be employed only in the side regions of the sheet stack, since all other surface parts are sufficiently influenced by the blast tubes.

Compressorsforthe blast of air through the blast tubes can be used for the generation of the suction current in the suction elements so that the use of further compressors is not necessary with utilization of the apparatus.

Claims

1. An apparatus for depositing sheets, comprising a sheet depositing station, at least one suction roller to engage a sheet being advanced horizontally towards the sheet deposit station, blower means to blow such sheet facially onto the deposit station, and suction means disposed at lateral regions of upstream portions of the deposit station for sucking air from the region of the deposit station to accelerate deposit of such sheets at the deposit station.

2. An apparatus as claimed in claim 1, the suction means being disposed below the suction roller.

3. An apparatus as claimed in either claim 1 or claim 2, the suction means being mounted to a crossbeam to be pivotable towards and away from an operational position thereof.

4. An apparatus as claimed in any one of the preceding claims, the suction means comprising a suction device disposed between adjacent suction rollers.

5. An apparatus as claimed in any one of the preceding claims, comprising means to cyclically control the suction means.

6. An apparatus as claimed in any one of the preceding claims, the suction means comprising a suction opening covered by a gauze member.

7. An apparatus for depositing sheets, substantially as herein before described with reference to Figure 1 and Figure 2 ofthe accompanying drawings.

8. An apparatus as claimed in claim 7 and modified substantially as hereinbefore described with reference to Figure 3 of the accompanying drawings.