GB2038785A

GB2038785A - Improvements in or relating to offset printing or duplicating machines

Info

Publication number: GB2038785A
Application number: GB8000547A
Authority: GB
Original assignee: Rotaprint GmbH
Current assignee: Rotaprint GmbH
Priority date: 1979-01-09
Filing date: 1980-01-08
Publication date: 1980-07-30
Also published as: GB2038785B; FR2446247B3; DE2900645B2; IT1129955B; JPS55115545A; DE2900645C3; IT8019111A0; DE2900645A1; FR2446247A1

Abstract

A safety device for enabling removal of sample sheets from offset printing or duplicating machines has a flap 3 pivotable on an axle 1 located in front of the front steps 6 of a sheet search receptacle and having a vertical position 10 and a horizontal position 11. In the horizontal position 10 access to the sheets in the direction of arrow A is not permitted and in the horizontal position 11 access to the stack of sheets 9 is permitted whilst blocking off manual access to transporting grippers 13. <IMAGE>

Description

SPECIFICATION Improvements in or relating to offset printing or duplicating machines This invention relatesto offset printing orduplicat- ing machines and in particular to a safety device for enabling removal of sample sheets from such machines.

In-a so-called chain deliverer having grippers which are fixed by means of gripper bridges to circulating chains, sheets, which after printing come from the impression cylinder of an offset machine or duplicating machine, are gripped by the grippers and transported against stops or flyers, from which the sheets drop onto a sheet stack. Moving pushers constantly align the uppermost sheets of the stack against stops.

In order to take out a sheet manually, for example to check the print quality, the procedure in the prior art is to pivot the stops out of the way so as to take one or more sheets from the stack or so as to take outone of the sheets which is dropping onto the stack. When taking out a sheet In this way, the hand of the operator is dangerously placed into the zone between the flyer and the gripper bridge thereby creating a considerable danger of injury: Solutions have been disclosed in which, as a result of pivoting the stops out of the way, the point in time at which the grippers open is simultaneously altered slightly, so as to take place later, the object being that the rapidly moving sheets should virtually be thrown into-the hand of the operator. This ejection is however not achieved reliably for all qualities of sheet, and especially not for light, thin sheets.The consequence is that the operator again, as described above, takes the sheet from the stack or places his hand on the stack to allow a sheet to drop into his hand. As a result, the operator's hand again comes into the danger zone of the gripper bridges. Since the printing machines process up to more than 15,00 sheets per hour, the constant succession of sheets also presents the person taking out a sheet with difficulties, so that he attempts to take the sheet out in the short period of time before the next sheet is delivered onto the stack. This naturally draws the concentration of the operator to the process of taking out a sheet and he does not pay a great deal of attention to the danger zone.

In recognition ofthe dangers resulting from this manipulation. photocell barriers are therefore frequently installed, which make this- danger zone safe in that, if the beam of the photocell barner is interrupted. the machine is stopped. Such a solution is on the one hand technically relatively complicated and on the other hand necessitates that the machine is stopped abruptly, since otherwise the safety measures are useless.

Levers which can be pivoted into position have also been disclosed. which, whilst taking out a sheet, catch the next sheet in such a way that the gripper edge of the sheet to be taken out remains free. It is true that this in part facilitates taking out a sheet by hand, but it cannot prevent the operator's hand from inadvertently coming into the danger zone between the gripper bridge and the flyer.

It is an object of the present invention to provide a safety device for an offset printing or duplicating machine which will permit safe taking out of an individual sheet with the machine running, without entailing considerable design effort or technical effort. A specific object is to prevent-the possibility of the operator inadvertently placing his hand in the zone arond the flyer and the moving gripper bridges of a chain deliverer machine.

According to this invention there is provided a safety device for enabling removal of sample sheets from offset printing or duplicating machines having a chain delivererwhich transports the sheets from the impression cylinder against a plurality of flyers which form the front stop of the stack of printed sheets, comprising a continuous safety flap, which in the operating condition of the machine is located on the side of the flyers remote from the sheet stack, said flap being pivoted into a substantially horizontal position in the front region of the sheet delivery zone between the chain conveyor and the stack and having slots corresponding to the flyers, such that whenthe flap is pivoted into the takeout position the flyers interleave with the slots.

Preferably the safety flap is pivotably mounted on an axle which is horizontally arranged substantially parallel with the flyers and on the side of the flyers remote from the stack and in the operating position the flap is substantially vertical and arranged to block manual entry between the deliverer and the stack.

Advantageously the flyers are stationarily mounted and extend downwardly in the direction of the stack which has been delivered as far as a line which approximately corresponds to the axle, the flyers in the region below this line being replaced by sheet stops which are connected to the safety flap and hence are upwardly pivotal therewith.

Various embodiments according to the invention are conceivable. In each case however, with the machine in the operating state, the safety flap is so arranged behind the flyers (that is to say on the side remote from the stack) ahat it is approximately vertical and prevents the operator from in any way reaching into the zone between the moving gripper bridges and the upper edge of the stack. In this context it is, not so much the vertical orientation of the safety flap which matters, but rather the fact that reaching into the said zone is effectively prevented.

For taking out a sheet, the safety flap is pivoted into the takeout position, namely into a substantially horizontal position in the front zone of the sheet deliverer, between the chain conveyor carrying the gripper bridges, and the stack of sheets. At the same time, the flyers or stops must release the front edge of the stack to allow a sheet to be taken out. This release can be effected if the flyer is, in a known manner, pivoted or flipped slightly aside, either upwards or downwards, for the takeout process; alternatively, as in the preferred embodiment, the flyer is of a divided construction, with the upper part being stationary whilst the lower part is pivotal. This can be achieved by connecting the lower part to the safety flap.

The invention will now be described by way of example with reference to the accompanying drawings In which Figure 1 shows a side view of the apparatus in accordance with the invention and Figm'e2 2 shows a partial view in the direction of the arrow X in Figure 1.

Referring to Figures 1 and 2 a safety flap 3 provided with slots 7 is mounted on an axle 1.

manually rotatable through 90 - l20-, which axle is locked in one or both end positions by an engagement mechanism such as. for example, an over centre spring mechanism (not shown) in either position 10 or 11. A plurality of sheet stops 2 (oniy one of which Is shown for clarity are connected to the safety flap 3 and the safety flap 3 and the sheet stop 2 can be made in one piece provided the spatial circumstances allow this. A number of flyers 6 are stationarily mounted on the chain deliverer. nameiy on a crossbeam thereof. or on the frame. the crossbeam or frame not being shown in the drawing, and extend down to approximately aliqn with the axle 1.The number and arranaement of the flyers Is such that the slots 7 of the safety flap 3 interleave with and do not interfere with the flyers during the pivoting movement of the safety flap 3 from the substantially vertical operating position 10 (shown In solid lines) to the substantially horizontal takeout or removal position 11 (shown in chain lines. One oniy of the grippers 13 of the circulating gripper bridges, which are connected to the chain conveyor 20 is shown. the conveyor 20 travelling round a pulley 21.

In the operating position 10, the stack in the area of the sheet stop 2 cannot be touched by hand inserted from the direction of arrow A. and a sheet cannot be taken from the stack 9. since the safety flap 3. as shown In the Figures is of solid construction except for the slots 7. and thereby blocks the introduction of a hand In the direction of the arrow A.

With the machine running, the chain dippers transport the sheets In the known manner against the flver 6. and allow the sheets then to drop onto the stack 9. as is the case In the prior art.

To take out a sheet with the machine running. the safety flap 3 is moved in the direction of arrow D by operating a hand iever 4 from the operating position 10 into the takeout position 1-I. As a result the sheets 8. after strikinq the flvers 6. drop onto and are caught by the safety flap 3 which s In the takeout position 11 and stack themselves as shown at 12. Access. in the nirection of arrow A. to the gripper edge of the stack C In order to take out a sample sheet is now free but inadvertent access In the danger zone of the gripner bridges 13 from the stack 9 in the general direction of the arrow B is now blocked by the safety flap 3.

With the machine stopped. the procedure for taking out a sheet is also as described above, but with the difference that in this case no further sheets are being delivered onto the safety flap as shown at 12.

After a sheet has been taken out with the machine running, the safety flap 3 is moved back from the takeout position 11 into the operating position 10 and the sheets, which have been delivered onto the safety flap 3 at 12 now drop down onto the stack 9, and the apparatus continues to run normally, as described earlier.

Claims

1. A safety device for enabling removal of sample sheets frorn offset printing or duplicating machines having a chain deliverer which transports the sheets from the impression cylinder against a plurality of flyers which form the front stop of the stake of printed sheets, comprising a continuous safety flap, which in the operating condition of the machine is located on the side of the flyers remote from the sheet stack, said flap being pivotal into a substantially horizontal position in the front region of the sheet delivery zone between the chain con veyorand the stack and having slots corresponding to the flyers, such that when the flap is pivoted into the takeout positon the flyers interleave with the slots.

2. A safety device as claimed In Claim 1, wherein the safety tlap Is pivotably mounted on an axle which Is horizontally arranged substantially parallel with the flyers and on the side of the flyers remote from the stack.

3. A safety device as claimed in ciaim 1 or 2 wherein In the operating position the flap is substantially vertical and arranged to block manual entry between the deliverer and the stack.

4. A safety device as claimed in Claim 2, wherein the flyers are stationarily mounted and extend downwardly in in the direction of the stack which has been delivered as far as a line which approximately corresponds to the axle. the flyers in the region below this line being replaced by sheet stops which are connected to the safety flap and hence are upwardly pivotal therewith.

5. A safety device as claimed in Claim 4, wherein the sheet stops are constructed integrally with the safety flap.

6. A safety device as claimed in any preceding claim wherein the safety flap is biassed by a spring arrangement to the operating position and the takeout position.

7. A safety device as claimed in any preceding claim wherein the flap is arranged so that when pivoted Into a sheet removal position, sheets transported by the flyers are caught by the rotated top of the flap.

8. A safety device substantially as herein de scribed with reference to and as shown in the accompanying drawings.