US3625131A

US3625131A - Apparatus for automatically developing printing plates

Info

Publication number: US3625131A
Application number: US776995A
Authority: US
Inventors: Ewald Puls
Original assignee: Individual
Current assignee: Individual
Priority date: 1968-05-28
Filing date: 1968-11-19
Publication date: 1971-12-07
Anticipated expiration: 1988-12-07
Also published as: NL6908091A; DE1772512A1; GB1212317A

Abstract

An apparatus for the automatic developing of printing plates wherein at least two distributing rollers are positioned above a conveyor belt adapted to carry the printing plates to be processed, with each roller being mounted for rotation in a direction opposite to the direction of travel of the conveyor belt and being axially slidable transversely of the belt thereby to apply the developer uniformly to the surface of the plates in a manner similar to prior manual methods.

Description

United States Patent 72] Inventor Ewald Puls Altenrather Str. 30, D 521 Troisdorf, Germany [21] Appl. No. 776,995

[22] Filed Nov. 19, 1968 [45] Patented Dec. 7, 1971 [32] Priority May 28, 1968 [33] Germany [31] Pl7725l2.l

[54] APPARATUS FOR AUTOMATICALLY DEVELOPING PRINTING PLATES 14 Claims, 2 Drawing Figs.

[52] U.S. Cl 95/89 R, 95/89 A, 118/242 [51] Int. Cl G03d 5/06 [50] Field of Search 95/89 R, 89 I A, 89 F, 93, 94 R;118/242 [56] References Cited UNITED STATES PATENTS 3,435,749 4/1969 Cauwe etal.

1,946,627 2/1934 Karrer.. 95/89 UX 2,154,585 4/1939 Samandji.. 95/89 (FEED) 3,059,560 10/1962 Gutzmer 95/89 3,113,034 12/1963 Fix 118/242 X FOREIGN PATENTS 87,711 8/1959 Denmark .l 95/89 949,710 9/1956 Germany 95/89 997,409 7/1965 Great Britain 95/94 Primary E.raminer-Samuel S. Matthews Assistant Examiner- Robert P. Greiner Anorney--Oberlin, Maky, Donnelly & Renner ABSTRACT: An apparatus for the automatic developing of printing plates wherein at least two distributing rollers are positioned above a conveyor belt adapted to carry the printing plates to be processed, with each roller being mounted for rotation in a direction opposite to the direction of travel of the conveyor belt and being axially slidable transversely of the belt thereby to apply the developer uniformly to the surface of the plates in a manner similar to prior manual methods.

PATENTEUUEC mu 3.625.131

sum

1 or 2 FIG.1

YXXXXXXXXXXXX XX PATENIED DEC 7 Ian SHEET 2 OF 2 APPARATUS FOR AUTOMATICALLY DEVELOPING PRINTING PLATES The present invention relates to an apparatus for the automatic developing and rinsing of printing plates, particularly offset plates. The developing of printing plates is at present still carried out by hand since efforts to constructs a mechanical device for developing the plates as uniformly and in the same quality as by hand have not yet met with success. To be sure, attempts of developing ofiset plates mechanically have been made. In such attempts the developer was applied to the exposed plates by rollers that moved slightly in a lateral direction and performed a rotary movement. However, in carrying out this developing process, the development was not uniform, and the rollers for distributing the developer left stripes behind on the finished plates which reproduced the lateral movement of the rollers by a sinusoidal curve.

The rollers of these prior devices which failed in practice were not capable of imitating the rotary movement, hitherto executed manually, of the cloth imbued with developer and thus were not able to apply the developer to the plate uniformly and with a uniform action thereon.

An object of the present invention is to provide a mechanical apparatus capable of imitating in a practically identical way by mechanical movements the manual efiort hitherto required for the developing of printing plates and particularly offset plates.

To accomplish this task, the present invention provides an apparatus of the aforementioned kind and which includes a developing tank and a conveyor belt which carries the plates to be processed. The developer is distributed by at least two rollers positioned near the upper section of the belt, the rollers preferably rotating about their axes to the path of travel of said belt and in opposite directions being slidable back and forth in an axial direction. A washing tank with conveyor rollers for washing the completely developed printing plates is located adjacent the developing tank. In the washing tank, the developer is removed from the plates by means of sprays of water or another suitable washing liquid.

All rollers are preferably provided with a common drive mechanism, and devices for spraying the developer and the washing liquid are mounted in the individual tanks.

To provide a special support for the printing plates to be processed, the lower section of the conveyor belt passes through a liquid bath, e.g., through the developer flowing down from the printing plates in the developing tank. The upper surface of the conveyor belt is therefore always moist so that the smooth back surfaces of the printing plates adhere sufficiently to the conveyor belt but are lifted off therefrom without difficulty at the end of the developing tank prior to entry into the washing tank.

It has been found that the rotary movement of the pieces of cloth or the like used in the manual developing can be imitated in the best manner if the distributing rollers are driven in the direction opposite to the direction in which the printing plates are processed, and move laterally through a range of between 50 to 100 mm. Such lateral movement is preferably produced according to the present invention by a lever arm. The free end of the shaft mounting each distributing roller is operatively engaged by such lever arm whose other end is pivotally connected to a crank driven by a separated motor. Due to the rotary movement, in opposite directions, of the distributing rollers, the developer can be retained on the upper surface of the printing plates in larger quantities, e.g. in the form of an accumulation so that it acts with uniform intensity and for a sufficient period of time upon the individual plates. The relatively large lateral movement of the distributing rollers, in combination with the rotary movement in opposite directions simulates sufficiently the rotary movement required in manual operation.

The invention makes it possible to develop printing plates and particularly offset plates automatically, manual operation being largely avoided, in a quality indistinguishable from that obtained in manual developing. Thus, the speed of developing of printing plates and particularly offset plates can be substan tially increased.

In the accompanying drawings:

H6. 1 is a vertical cross-sectional view of the apparatus of the present invention, and

FIG. 2 is a sectional view taken along line 11-11 of FIG. 1.

Referring now in more detail to the drawing, wherein like parts are indicated by like reference numerals, a tank 2 for developing the offset plates is mounted on frame 1. The plates are fed into the apparatus over table 3 and leave the developing tank over table 4 which leads to a washing tank 5 fastened to a support 6 on the back of frame 1. The developing tank 2 consists of a detachable tub 7 and a hood 8 resting on lateral support pins 9.

The suction line 10 of pump 11 is connected to the drain outlet 7a of the tub 7. The pump 11 is driven by a drive mechanism (not shown) which circulates the developer in the form of bath 12 contained in tub 7 to spray devices to be presently described.

A conveyor belt 13 is mounted inside the developing tank 2, with the upper section of the belt lying in the same plane as tables 3 and 4, while the lower section of the belt 13 is immersed in bath 12. The conveyor belt 13 passes over a driven, deflecting roller 14 and a free roller 15, with the upper section of the conveyor belt 13 being held in a horizontal plane by

support rollers

16 and 17.

Two rotatable distributing

rollers

18 and 19 are mounted in the developing tank 2 above the conveyor belt 13, with the

rollers

18 and 19 being driven in a direction opposite to that of the movement of conveyor belt 13, as indicated by arrows 20 and 21. These distributing

rollers

18 and 19 are provided with a felt coat 22, and are arranged vertically directly above the

support rollers

16 and 17 and can be made to rest against these support rollers by means of adjusting handles 23 in a manner described below.

At the front and rear end of developing tank 2 press-on rollers 24 and 25 are mounted above the upper section of conveyor belt 13 and are in contact therewith. The rollers 24 and 25 provide a full abutment of the printing plates against the upper section of the conveyor belt 13 during the passage through developing tank 2.

In washing tank 5 are mounted two pairs of vertically aligned

conveyor rollers

26 and 27 which abut against each other and which conduct the developed printing plates through the washing tank. A device 28 for spraying washing water or the like is mounted between the

rollers

26 and 27, the device 28 spraying the processed printing plates from all sides with washing liquid. The space between

roller pairs

26 and 27 is so small that the printing plates are always seized and held by at least one of these roller pairs. A pump 29 for circulating the washing liquid is connected with the spraying device 28 by tube 30. The completely developed and rinsed printing plates leave washing tank 5 over table 31.

All driven rollers receive their rotary movement from a common drive motor, not shown in the drawing. For this purpose a chain drive is provided which is propelled by the drive motor and which passes over chain wheels coordinated with the individual rollers to be driven. FIG. 2 shows only one of these chain wheels, namely chain wheel 32 which is coordinated with one of the distributing rollers, namely 18.

Roller pairs

26 and 27 are driven at a reduced r.p.m. through a conventional reduction gear (not shown).

As shown in FIG. 2, distributing

rollers

18 and 19 are mounted on

stub shafts

33 and 34 mounted on frame 1 in vertically

adjustable support blocks

35 and 36. These support blocks can be vertically adjusted by means of adjusting handles 23 and adjusting spindles 37 connected thereto, whereby the spacing between the distributing rollers and conveyor belt 13 can be regulated. The support blocks are mounted so as to move vertically in lateral guides, e.g., in angle-shaped guide ribs or dovetail guides.

Bearing

bushings

38 and 39 are mounted in

support blocks

36 and 35, respectively, and rotate within

roller bearings

40 and 41. The drive chain wheel 32 is mounted on the outer end of bushing 38.

Stub shafts

33 and 34 are arranged so as to be axially displaceable in

bearing bushings

39 and 38, respectively, and are operatively connected thereto by carriers 42 in such a manner as to be secured against rotation. Thus, distributing

rollers

18 and 19 can be moved laterally back and forth above conveyor belt 13 in a manner described below, and are mounted for rotary movement about their longitudinal axes through chain wheels 32.

The entire drive mechanism is lodged in a casing 43 mounted laterally on frame 1, while the support blocks are covered by a casing 44 at the front side of the apparatus.

All support blocks of the distributing rollers are mounted in the guides so as to be easily replaceable, whereby the cleaning of the apparatus and a replacement of worn parts is greatly facilitated.

The free end of shaft 34 is mounted in a rotatable manner in a connecting yoke 46 by means of a roller bearing 45. Between the two ends of the connecting yoke 46, a slide ring 48 is rotatably mounted on a shaft 47. This slide ring 48 is positioned in a longitudinal groove 49 of an adjusting lever 50 which is mounted on a support 52 so as to pivot about a shaft 51. A crankarm 53 is hinged to the lower end of lever 50 via a link pin 54, with the other end of crankarm 53 being hinged eccentrically to a crank disk 56 by means of a pin 55. Crank disk 56 is mounted on a gear 57 and is driven by a motor 58 mounted on a baseplate 59 on frame 1.

it will thus be seen that the lateral displacement of the distributing

rollers

18 and 19 depends on the distance of pin 55 from the center of crank disk 56 and the ratio of the length of the two portions of lever 50 located above and below pivot point 51. This lateral displacement range generally need not exceed 100 mm. and ranges preferably between 50 and 100 mm., regardless of the width of the operative portion of the apparatus.

Two

spray devices

60 and 61 are directed against distributing roller 19, which is the first roller encountered in the processing. These spraying

devices

60 and 61 spray the developer on the upper surface of conveyor belt 13 and the distributing roller 19, and thus to the upper surface of the printing plates (not shown) as indicated by dashed lines 62. These spray devices consist preferably of hollow rods with spray nozzles 63 arranged and uniformly spaced on the bottom side of these rods.

As shown in FIG. 1, spray device 60 applies the developer directly to the felt coat 22 of distributing roller 19, while spray device 61 sprays the developer both against distributing roller 19 and also directly upon conveyor belt 13 and the printing plates placed thereon. Since distributing roller l9 rotates in a direction opposite to that in which the conveyor belt 13 moves, a wedge-shaped accumulation 64 of developer forms in front of the distributing roller 19 so that the printing plates are thoroughly immersed in developer. The developing by means of the present invention is thus carried out as uniformly as by hand, i.e., no unequally developed spots or stripes appear on the finished printing plates.

I claim:

1. Apparatus for providing a uniform coat of developer on printing plates, comprising a developing tank containing developer, a conveyor belt adapted to carry the printing plates to be processed, at least two longitudinally spaced rollers mounted above and relatively adjacent said conveyor belt, means adjacent at least one of said rollers for distributing the developer on said printing plates, means for rotating said rollers in a direction opposite to the direction of travel of said conveyor belt, and means for moving said rollers axially in a direction transverse to said conveyor belt to provide a uniform coat of developer on the printing plates.

2. The apparatus of claim 1, further including a washing tank mounted adjacent said developing tank, said washing tank having mounted therein a plurality of vertically spaced conveying rollers adapted to engage said plates.

3. The apparatus of claim 2, wherein said washing tank is provided with a spray device for rinsing the plates with the washin liquid.

4. T e apparatus of claim 2, further including a common drive mechanism for all of said rollers.

5. The apparatus of claim 1, further including at least one spray device for spraying the developer directly against the first of said distributing rollers, as seen in the direction of the processing sequence.

6. The apparatus of claim 5 wherein said one spraying device is directed against the top of said first distributing roller, and further including a second spray device for spraying developer perpendicularly against the surface of the said first distributing roller.

7. The apparatus of claim 1 wherein said distributing rollers are provided with a coat of absorbent material.

8. The apparatus of claim 1 wherein said conveyor belt comprises an endless belt the lower section of which passes through the developer bath.

9. The apparatus of claim 8 further including circulating pump means for pumping developer from said bath to spray devices positioned above at least one of said distributing rollers.

10. The apparatus of claim 1 wherein said distributing rollers are moved axially back and forth by means of a lever operatively connected to a motor.

11. The apparatus of claim 10 wherein said distributing rollers are mounted on shafts axially slidable in bearing bushings, one end of each of said shafts being engaged by said lever.

12. The apparatus of claim 11 wherein at least one bearing bushing of each distributing roller is rotatably connected with a drive mechanism and the distributing roller is carried along by this bearing bushing by a carrier.

13. The apparatus of claim 11 wherein said bearing bushings are each positioned in a support block, and means for vertically adjusting each of said support blocks from the outside of the frame of the apparatus.

14. The apparatus of claim 1 wherein the range of axial movement of said distributing rollers is 50 to mm.

Claims

3. The apparatus of claim 2, wherein said washing tank is provided with a spray device for rinsing the plates with the washing liquid.

4. The apparatus of claim 2, further including a common drive mechanism for all of said rollers.

14. The apparatus of claim 1 wherein the range of axial movement of said distributing rollers is 50 to 100 mm.