GB2245374A

GB2245374A - Plate handling apparatus

Info

Publication number: GB2245374A
Application number: GB9011945A
Authority: GB
Inventors: John Richard Snook
Original assignee: PRINTING TECH EQUIPMENT Ltd
Current assignee: PRINTING TECH EQUIPMENT Ltd
Priority date: 1990-05-29
Filing date: 1990-05-29
Publication date: 1992-01-02
Anticipated expiration: 2010-05-29
Also published as: GB2245374B; GB9011945D0

Abstract

The apparatus transfers a plate to an exposure table (10), and the plate is moved to abut fixed register pins (13) adjacent said table. Punch heads (14) punch register holes once the plate is located and operate simultaneously with the exposure of the plate. Initially suction pads (15) attached to a transport frame (4) lift a top plate from a stack of plates, and a fan is disposed to direct a stream of air substantially horizontally between the top plate and the top of the stack of plates in order to aid separation of the plate and to entrain interleaving disposed between the plates. <IMAGE>

Description

PLATE HANDLING APPARATUS The present invention relates to a method and apparatus for handling printing plates.

In modern printing techniques, particularly, but not exclusively in the field of newspaper printing, it is known to photograph the image on a paste-up sheet using electrostatic film which can be developed and fixed. At a later stage in the process, the image is illuminated with ultraviolet light to project the image onto a printing plate. Obviously, it is necessary for the printing plate to be in register with the position of the image. To this end, the printing plate is fixed on the exposure table by cooperation between register holes punched in the plate and register pins adjacent the table. As may be seen, this requires two stages of treatment of the printing plate, firstly it must be punched accurately and then transferred from the punching machine to the exposure table and aligned by means of the register holes.

One object of the present invention is to simplify this procedure by enabling a single step to cover both of these actions.

The printing plates used are generally precoated and are held in a stack of plates, with the plates separated by sheets of interleaving. Hitherto, it has not always been easy to separate the plate from the interleaving when it is transferred to the punching machine or the exposure table.

It is another object of the present invention to provide a method and apparatus of transferring plates automatically from a stack and simultaneously removing the interleaving by automatic means.

According to a first aspect of the present invention there is provided a printing plate handling apparatus in which a plate is transferred to an exposure table, wherein means are provided for moving said plate to abut fixed register pin means adjacent said table and means are provided to punch register holes, said punch means being operative once the plate is located and simultaneously with the exposure of the plate.

Preferably the plate is held immobile on the table by vacuum means once it has been located.

The plate may be moved by floating register stop means, the or each stop means being movable under the influence of a hydraulic or pneumatic ram means.

There are advaneageously two floatil. reg,ste stop means, a first one located at an end of the plate and acting in longitudinal direction thereof, and a second one disposed at a side of the plate and acting in transverse direction thereof.

In this case, there are advantageously four fixed register pin means, two disposed at an end of the plate opposite said first floating register stop means and two disposed at a side of the plate opposite said second floating register stop means.

A number of punch means are provided, disposed at spaced locations adjacent the periphery of the plate when located. Optionally, three to six punch means may be provided, although more or less could be used if so desired.

According to a second aspect of the present invention there is provided a printing plate handling apparatus comprising suction lifting means to lift a top plate from a stack of plates, and fan means so disposed as to direct a stream of air substantially horizontally between said top plate and the top of the stack of plates, said stream of air aiding separation of the plate and entraining interleaving disposed between the plates.

Preferably the stream of air is directed towards a waste tray means where are deposited the entrained sheets of interleaving.

Additional fan means may be provided downstream of the stack of plates. This may be to ensure entrainment of the interleaving sheets until they are deposited in the waste tray means.

According to a third aspect of the present invention there is provided a method of handling printing plates comprising the steps of transferring a plate from a stack of plates to an exposure table, moving said plate into register on said table, simultaneously punching register holes in the plate and exposing it, and transferring the punched and exposed plate to a further processing step.

Preferably said step of transferring a plate from a stack of plates comprises the steps of lifting a top one of the stack of plates and simultaneously directing a stream of air across the stack to aid separation of the top plate and to entrain an interleaving sheet below said top one for removal of the interleaving sheet.

An embodiment 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 is a plan view of an apparatus embodying the invention; FIGURE 2 is a side elevation of the apparatus; and FIGURE 3 is an end view of the apparatus.

Referring now to the drawings, a stack 1 of precoated plates is supported on a table at the input end of the apparatus. First fans 2 are adapted to direct a stream of air in the general direction of arrow 3 across the top of the stack. A plate transport frame 4 is provided with suckers 5, of which six are shown although the number may be greater or less depending on the area of the plate being transported. The suckers 5 are mounted to a plate lift frame 6 which may descend until the suckers are in contact with the top plate of the stack 1. As the top plate is lifted on retraction of the plate lift frame 6, the stream of air 3 aids separation of that plate from the next, and also entrains the sheet of interleaving, which ray be tissue paper or the like, and carries it away from the stack of plates.The air flow from stream 3 is then directed downwardly and a second stream of air in the direction of arrow 7 is introduced by means of fans 8 to carry the sheets of interleaving into a waste tray 9.

The top most plate, held by the suckers 5 and plate lift frame 6, is then transferred by means of plate transport frame 4 to the next work station, where it is deposited on a vacuum table 10. The plate lift frame 6 then returns to its initial pos#t#or, ready for the next plate.

The plate is moved across the vacuum table 10 by means of a pair of floating register stops 11, each operated by a respective hydraulic or pneumatic ram 12. Movement stops when the plate is located against four fixed register pins 13. Vacuum is then applied to the table to maintain the plate in position and punch heads 14 are actuated to cause the plate punches to cut register holes in the plate.

In the drawing, three punch heads 14 are shown. However, more or less may be provided as desired. Whilst the plate punches are still engaged in the dies, the plate is exposed to the image projected from above. The plate punches are then retracted and the plate vacuum released. The punched and exposed plate is then lifted clear of the vacuum table 10 by means of suction pads 15, which swing down to grip the front edge of the exposed plate.

The plate transport frame 4 then moves to bring the next plate from the stack 1 to the vacuum table 10 and also to move the exposed plate, held by the suction pads 15 to a position above conveyor 16 from which it passes to further processing steps.

The sequence is then repeated for each subsequent plate.

The system offers advantages both in time, space and manpower in that the punching and exposure steps are performed simultaneously in a single location. Also, the plate is automatically in register for both the punching step and the exposure step. Furthermore, the automatic feed and de-leaving of plates also offers significant savings.

Claims

CLAIMS:

1. A printing plate handling apparatus in which a plate is transferred to an exposure table, wherein means are provided for moving said plate to abut fixed register pin means adjacent said table and means are provided to punch register holes, said punch means being operative once the plate is located and simultaneously with the exposure of the plate.

2. An apparatus as claimed in claim 1, wherein the plate is held immobile on the table by vacuum means once it has been located.

3. An apparatus as claimed in either claim 1 or claim 2, wherein the plate is moved by floating register stop means, the or each stop means being movable under the.

influence of a hydraulic or pneumatic ram means.

4. An apparatus as claimed in claim 3, wherein there are two floating register stop means, a first one located at an end of the plate and acting in longitudinal direction thereof, and a second one disposed at a side of the plate and acting in transverse direction thereof.

5. An apparatus as claimed in claim 4, wherein there are four fixed register pin means, two disposed at an end of the plate opposite said first floating register stop means and two disposed at a side of the plate opposite said second floating' register stop means.

6. An apparatus as claimed in any one of the preceding claims, wherein a plurality of punch means are provided, disposed at spaced locations adjacent the periphery of the plate when located.

7. A printing plate handling apparatus comprising suction lifting means to lift a top plate from a stack of plates, and fan means so disposed as to direct a stream of air substantially horizontally between said top plate and the top of the stack of plates, said stream of air aiding separation of the plate and entraining interleaving disposed between the plates.

8. An apparatus as claimed in claim 7, wherein the stream of air is directed towards a waste tray means where are deposited the entrained sheets of interleaving.

9. A method of handling printing plates comprising the steps of transferriny a plate from a stack of plates to an exposure table, moving said plate into register on said table, simultaneously punching register holes in the plate and exposing it, and transferring the punched and exposed plate to a further processing step.

10. A method as claimed in claim 9, wherein said step of transferring a plate from a stack of plates comprises the steps of lifting a top one of the stack of plates and simultaneously directing a stream of air across the stack to aid separation of the top plate and to entrain an interleaving sheet below said top one for removal of the interleaviny sheet.

11.' A printing plate handling apparatus substantially as described herein with reference to the accompanying drawings.