US3792658A

US3792658A - Rotary printing machine with stop members for cylinder adjustments

Info

Publication number: US3792658A
Application number: US00226637A
Authority: US
Inventors: D Shore; D Hart
Original assignee: Colodense Ltd
Current assignee: Colodense Ltd
Priority date: 1971-02-19
Filing date: 1972-02-15
Publication date: 1974-02-19
Anticipated expiration: 1991-02-19
Also published as: IT947703B; FR2144195A5; GB1374814A; DE2208105A1; DE2208105B2; DE2208105C3

Abstract

The plate roller of a printing machine is urged at each end towards its operative position in contact with the impression roller. Detachable stop members of preselected size are provided at each end to limit the forward movement of the plate roller at its operative position. At each end various sizes of stop members can be provided on a carrier arranged to move them individually into position. The stop members can act between pairs of abutments and counter abutments, at least one of which is movable to provide fine adjustment. Screw adjustments, optionally remotely controlled, can be provided for final adjustment of the position of each end of the plate roller. A similar arrangement is provided for determining the position of the transfer roller in relation to the plate roller.

Description

United States Patent 1 Shore et al.

[ Feb. 19, 1974 ROTARY PRINTING MACHINE WITH STOP MEMBERS FOR CYLINDER ADJUSTMENTS [75] Inventors: Donald Arthur Shore; David Edward Hart, both of Bristol, England [30] Foreign Application Priority Data Feb. 19, 1971 Great Britain 4975/71 Aug. 25, 1971 Great Britain 39818/71 Nov. 11, 1971 Great Britain 52522/71 [52] US. Cl. 101/247, 101/352 [51] Int. Cl. B4lf'l3/34, B41f31/30 [58] Field of Search... 101/247, 137, 139, 140, 143, 10l/144,145,182,184, 185, 351, 352; 92/13.413.8

2,925,802 2/1960 White, Jr, 92/13.4 X 2,991,760 7/1961 Rhine 92/138 X 3,041,967 7/1962 Nystrand 101/182 3,117,516 1/1964 Oderman et al. 101/365 3,259,060 7/1966 Martin 101/247 X 3,366,049 1/1968 Nystrand... 101/247 3,611,926 10/1971 Johnson 101/247 Primary Examiner-J. Reed Fisher [5 7] ABSTRACT The plate roller of a printing machine is urged at each end towards its operative position in contact with the impression roller. Detachable stop members of preselected size are provided at each end to limit the forward movement of the plate roller at its operative position. At each end various sizes of stop members can be provided on a carrier arranged to move them individually into position. The stop members can act between pairs of abutments and counter abutments, at least one of which is movable to provide fine adjustment. Screw adjustments, optionally remotely controlled, can be provided for final adjustment of the position of each end of the plate roller. A similar arrangement is provided for determining the position of the transfer roller in relation to the plate roller.

19 Claims, 9 Drawing Figures APAIENTEUFEBIQW 3192.658

SHEET '2 [IF 3 ROTARY PRINTING MACHINE WlTll-I STOP MEMBERS FOR CYLINDER ADJUSTMENTS This invention relates to printing machines, printing proof machines, make-ready machines and like applicator machines of the rotary type hereinafter referred to as printing machines.

In rotary printing machines of known type, printing impressions are made on a web such as paper or film by passing the web between an impression cylinder and a plate roller which bears the printing plates, for example flexographic plates. The plate roller is supplied with ink by a transfer roller which in turn receives ink from an inking roller dipping in a trough containing inks.

In order to obtain print impressions of high quality, it is essential that the positioning of the plate roller with respect to the impression cylinder and of the transfer roller with respect to the plate roller is under very accurate positive control. This is particularly essential in multichromatic printing when two or more separate printing operations are carried out as the web passes round the impression cylinder, each operation providing a precise area of primary colour.

High accuracy of control is obtained by the use of cylinders and rollers manufactured to close tolerances mounted in bearings of high precision and by the use of printing plates made to a high degree of accuracy.

In known printing machines is positioning of the plate roller with respect to the impression cylinder and the transfer roller with respect to the plate roller is brought about by means of accurately manufactured screw thread situated at each end of each roller. The screw threads are usually operated by hand singly or together to obtain the precise operating position by trial and error with reference to the print quality.

Unless the screw threads are maintained in very good condition, there is a tendency for the plate and transfer rollers to move out of setting after running for some time due to vibrations and other movements which requires further adjustment of the screw threads.

Moreover, during the course of a production run it is sometimes necessary to withdraw the plate roller and transfer roller from their operating positions to attend to a fault for example when paper has adhered to and is wound around the plate roller when the entire setting-up procedure with the screw threads has to be performed to reposition the rollers in their operative position.

Still further, when the plate roller is replaced by one of a different diameter to effect a new printing having a new print length, the entire setting-up procedure with the screw threads has to be repeated for the new positioning of the rollers.

The time taken for positioning or repositioning of the rollers with the screw threads is time consuming and it is important that it should be as short as possible for efficient working.

The present invention is concerned with an improved means for bringing the plate roller and transfer roller into their positive operating printing positions.

According to the present invention, a printing machine comprises an impression cylinder mounted for rotation, and at least one printing station comprising a plate roller capable of being moved towards and away from the impression cylinder, a transfer roller capable of being moved towards and away from the plate roller, urging means at each end of the plate rollers for pressing the plate roller towards the impression cylinder,

first detachable stop members of preselected size for determining the limit of movement of each end of the plate roller towards the impression cylinder at substantially the operative position for the plate roller, urging means at each end of the transfer roller for pressing the transfer roller towards the plate roller and second detachable stop members of preselected size for determining the limit of movement of each end of the transfer roller towards the plate roller at substantially the operative position for the transfer roller.

The urging means for the plate roller and transfer roller may conveniently be fluid operated pressure means for example, pneumatic or hydraulic cylinders, which also serve to move the plate roller and transfer roller away from their operative positions.

By detachable stop member is meant a stop member which is not permanently fixed in its operative position but which is readily replaceable when required by another stop member.

Preferably each first detachable stop member lies be tween a first abutment connected in fixed relationship to a bearing for an end of the plate roller and afirst counter abutment connected in fixed relationship to a bearing for a corresponding end of the impression cylinder, and each second detachable stop member lies between a second abutment connected in fixed relationship to a bearing for an end of the transfer roller and a second counter abutment connected in fixed re lationship to a bearing for a corresponding end of the plate roller, at least one of each pair of said abutments and counter abutment, and preferably said abutment, being movable to provide fine adjustment for the operative positions of the plate and transfer rollers.

By preselection of the size of the detachable stop members for a particular combination of plate roller and transfer roller, the plate roller and transfer roller may be positively brought substantially into their oper ative positions by the urging means. A final critical setting of the rollers may be made, if required, by means of a screw member having a fine pitch screw thread.

It is necessary to withdraw the plate roller with its transfer roller away from the impression cylinder for a temporary stoppage, on clearance of the fault the plate roller and transfer roller may be moved back into their operating positions with the minimum of delay or adjustment for recommencement of the printing operation.

On change of plate roller to a plate roller of different size, all that is required is the replacement of the stop members with other stop members of preselected size which ensure that on urging the new plate roller and transfer roller forward towards the impression cylinder, both rollers are rapidly brought up to and are positively held in substantially their operating positions. Thus, non-productive time taken for setting up after a change of printing roller is reduced to a minimum.

In one form of the invention the plate roller and the transfer roller are each movable by piston rods of fluid operated cylinders acting upon a bearing at each end of each roller and the detachable stop members are tubes of preselected length fitted over rearwardly extending portions of the piston rods and retained on the rods by releasable fasteners of a size larger than the bore of the tubes so as to limit the extent of the forward movement of the piston rods when the fluid operated cylinders are operated. The fasteners, for example U- pieces, are readily removed for easy replacement of the tubes by other tubes of a different length when required.

In another form of the invention, the detachable stop members are bars of preselected length which may conveniently lie in V-shaped grooves formed in rods which extend from bearings at the ends of the plate roller and the transfer roller in a direction opposite to the direction of thrust of the urging means. Each bar lies between an abutment mounted on the rod and a counter abutment which is mounted in fixed relation to a bearing at the end of the impression cylinder or a bearing at the end of the plate roller and limits the extent of forward motion of the rod when the bar is trapped between the abutments.

The rods may be rearwardly extending portions of piston rods of fluid operated cylinders acting upon bearings at each end of the plate roller and the transfer roller for the purpose of moving the rollers. The forward motion of each piston rod is arrested when an abutment carried near the end of the rod makes contact with an end of the bar and carries the bar forward until the other end of the bar makes contact with a counter abutment.

Alternatively the rods for supporting the bars are separate from the fluid operated cylinders but lie parallel with the piston rods. In this arrangement the counter abutment is conveniently a part of the frame through which the rods slide.

In order to accommodate a wide range of plate cylinders of different sizes, that is of different print lengths, it is necessary to keep in stock a large number of detachable stops of different preselected lengths for each stop position. In practice this requires at least twenty or more stop members for each stop position or eighty or more for each printing station. For multicolour printing machines having two or more printing stations placed around the impression cylinder each printing station will require sets of stop members which in some circumstances will differ from the range of sizes of stop members in other printing stations due to changes in the positioning of parts being necessary for different circumferential positions of printing stations around the impression cylinder.

This large number of stop members must necessarily be held adjacent to the printing machine, for example in a container with the different sizes clearly marked. Preferably, however, when the stop members are bars, at least two suitably sized bars are linked together adjacent the operative position for the selected bar. This obviates the use of a storage container with the hand sorting and the possible mislaying of the required stop member.

When it is necessary to change a bar stop member, all that is required is to lift the bar from its operative position on the rod, move the series along to select the replacement bar of required size and fit it into the operative position on the rod.

The bar stop members may be linked together by a band consisting of a strip or a closed loop to which the stop members are fastened at suitable spaced intervals or threaded by means of holes formed transversely through the body of the members. The band may be flexible or semi-rigid and formed into a circle or oval to facilitate handling. A suitable band is a belt of polypropylene.

In still another form of the invention the detachable stop members are bars of preselected length of which two or more are mounted in one end of a rotatable turret whereby a selected bar can be brought into an operative position by rotation of the turret.

A screw member is preferably provided adjacent each stop member position for effecting a final manual critical setting of the position of the plate roller with respect to the impression cylinder and the position of the transfer roller with respect to the plate roller. Each screw member has a fine screw thread and is limited in rotational movement. It may be operated by a hand lever when the position of the lever gives a visual indication to the operator of the rotational position of the screw member.

It will be appreciated by those skilled in the art that the optimum setting, which interalia, depends upon the printing speed and the ink viscosity, can only be achieved when the press is running at full operating speed. Under these conditions, the quality of the printed image may be viewed by the use of a known stroboscopic device.

It is advantageous to operate each screw member remotely from a position adjacent to the printed running web whereby any minor irregularities in positioning of the plate roller or transfer roller as shown by the printed image can be corrected by operation of the appropriate screw member or screw members with direct reference to the printed image.

Various embodiments of the invention will now be more specifically described with reference to the drawings wherein:

FIG. 1 is a diagrammatic side elevation of a printing machine;

FIG. 2 is a detail of FIG. 1;

FIG. 3 is a detail of FIG. 2;

FIG. 4 is a diagrammatic side elevation of a printing machine illustrating a second form of the invention;

FIG. 5 is a detail of FIG. 4;

FIG. 6 is an enlarged section through a part of FIG.

FIG. 7 is a detail of a modified form'of the invention illustrated in FIG. 4;

FIG. 8 is an enlarged vertical cross-section of part of FIG. 7; and

FIG. 9 is an end view of part of FIG. 7.

Referring to FIG. 1, an impression cylinder 1 is mounted for rotation in fixed bearings 2 mounted in a machine frame 3. A printing plate roller 4, for example bearing flexographic printing plates 4' is mounted for rotation at each side of the machine in bearings 5 mounted within slidable members 6 which are capable of sliding in slides 7 in the frame 3. A transfer roller 8 is mounted for rotation in bearings 9 in second slidable members 10 which are capable of sliding in slides 1 1 on the slidable members 6. An inking roller 12 is also mounted in bearings 13 in the slidable members 10 and is maintained in adjustable nipping contact with the transfer roller 8. It will be appreciated that the parts shown in side elevation in FIG. I are repeated at the opposite side elevation. The inking roller 12 dips into an ink hath (not shown) and meters ink to the transfer roller 8 which in turn transfers ink to the printing plates on the plate roller 4.

The movement of the slidable members 6 along the slides 7 is controlled by two pneumatic cylinders 14 fixed to the frame 3 and having piston rods 15 which bear against the slidable members 6. The movement of the second slidable members 10 in the slides 11 is controlled by two further pneumatic cylinders 16 each mounted to a slidable member 6 and each having piston rods 17 which bear against the slidable member 10.

As shown in FIG. 2, the piston rod of each pneumatic cylinder 14 extends rearwardly through the cylinder l4, and is encircled by a readily detachable tubular stop member 18 (FIG. 3) which is maintained on the rod 15 by a U-piece 19 fitting into an annular groove 20 towards the end of the rod 15. When pneumatic pressure is applied to the cylinder to drive the rod 15 in a forward direction as shown by the arrow 21, a position is reached when the stop member bears against the bolt 19 and a screw member 22 formed at the end of the cylinder 14 (as shown in FIG. 2) and prevents further forward movement of the rod 15. The screw member 22 has a very fine thread which provides a forward- /backward movement of up to about 0.021 inch so as to effect a final manual critical setting when the rod 15 is arrested in its forward position by the stop member 18. The forward end of the rod 15 is screwed into the slidable member 6 and is adjusted as may be required on construction of the machine, to take up small inaccuracies in the components employed. The rod 15 is locked into position by a locking nut 23 which is permanently pinned into place to prevent any further movement.

The pneumatic cylinders 16 with rods 17 are similar in all respects in construction and operation to the cylinder 14 described with reference to FIG. 2 and FIG. 3 and are fitted with similar cylindrical stop members 24 and screw members 25.

It will be appreciated that the

screw members

22, 25 are used only for any fine critical adjustment which may be required to allow for variations in impression resulting from printing plate thickness differences from one side of the plate roller to the other or from one printing plate to the next or for printing speed or ink viscosity and not for any principal working movement of the rollers as is the case with screw threads of the prior art. An operating lever or pointer may be fitted to the

screw members

22, 25 whereby the rotational position of the

members

22, 25 may readily be observed by the machine operator.

In operation of the machine, the stop members 18 on each of the rods 15 are selected to be of such a length that on forward motion of the rods 15 the motion is arrested When the plate roller 4 is positioned in substantially the desired operating position with respect to the impression cylinder 1. Any final critical setting necessary can be effected by the screw member 22. Similarly, the stop members 24 on the rods 17 of each of the pneumatic cylinders 16 are selected to be of such a length that on forward motion of the rods 17 the motion is arrested when the transfer roller 8 is precisely positioned as required with respect to the plate roller 4. A final critical setting can be made, if required, by means of the screw member 25.

By these means, the plate roller 4 and transfer roller 8 with its associated inking roller 12 can readily be brought into and out of these operative positions. Thus at any time the plate roller 4 and the transfer roller 8 may be withdrawn for a temporary interruption of printing and application of printing ink to the plate roller 4 and then may be accurately placed back into their former operative positions. The force applied by the

pneumatic cylinders

14, 16 holds the rollers 4, 8 positively in position and the pressure applied through the

screw members

22, 25 prevents any disturbance of the settings by vibration.

When it becomes necessary to change the plate roller 4 for another roller 4 of different diameter to effect a change of printing, the necessary repositioning of the new plate roller 4 and the transfer roller 8 is rapidly and readily carried out by replacing the

stop members

18, 24 by new members of the precise length required to set the limits for the forward motions of the rods l5, 17. The lengths of the

stop members

18, 24 may be determined by calculation or may be previously determined on a print proving machine of identical design to the production printing machine so that the nonproductive time taken in effecting the change on the production machine is reduced to a minimum.

Referring to FIG. 4, an impression cylinder 31 is mounted for rotation on fixed bearings 32 mounted in a machine frame 33. A printing plate roller 34, for eX ample bearing flexographic printing plates 34' is mounted for rotation at each side of the machine in bearings 35 mounted within slidablle members 36 which are capable of sliding in slides 37 in the frame 33. A transfer roller 38 is mounted for rotation in bearings 39 in second slidable members 40 which are capable of sliding in slides 41 on the slidable members 36. An inking roller 42 is also mounted in bearings 43 in the slidable members 40 and is maintained in adjustable nipping contact with the transfer roller 38. The inking roller 42 dips into an ink bath (not shown) and meters ink to the transer roller 38 which in turn transfers ink to the printing plates of the plate roller 34.

It will be appreciated that the parts shown in side elevation in FIG. 4 are repeated in the opposite side elevation.

The movements of the slidable members 36 along the slides 37 are each controlled by hydraulic cylinders 44 fixed to an upright member 45 of the frame 33 and having piston rods 46 which are secured at their ends to the slidable members 36. The movements of the second slidable members 40 in the slides 41 are each controlled by two further hydraulic cylinders 47 each mounted to an upright member 48 of a slidable member 36 and each having a piston rod 49 which is secured at its end to the slidable member 40.

As shown particularly in FIG. 5, two

rods

50, 51 lying below and parallel with the piston rod 46 are secured at one end to the slidable member 36 and pass freely through holes 52 in the upright member 45 below the hydraulic cylinder 44. At the ends remote from the slidable member 36 the

rods

50, 51 join and form a housing for a screw member 53 having an abutment 54. The screw member 53 has a fine screw thread which provides a forward/backward movement of up to about 0.021 inch for the purpose of effecting a final manual critical setting as hereinafter described. Fixed to the upright member 45 between the holes 52 by a locked screw 55 is a counter abutment 56 facing the abutment 54.

The rod 52 is grooved on its upper surface to receive and support a bar stop member 57 with its longitudinal axis along a line between the

abutments

54, 56.

On operation of the hydraulic cylinder 44 to draw the slidable member 36 towards the upright member 45 the abutment 54 moves away from the counter abutment- 56. On reversal of the movement, the abutment 54 moves towards the abutment 56 and is stopped by the bar stop member 57 pressed between the

abutments

54, 56. The bar stop member 57 is of predetermined size to ensure that the plate roller 34 is brought up to the desired position in respect of the impression cylinder 31; any final fine critical setting which may be necessary being made by the screw member 53. The continuing pressure exerted by the hydraulic cylinder 44 holds the slidable member 36 and the plate cylinder 34 positively in the desired position and in view of the stop member 57 being out of alignment with the piston rod 46, the resultant moment of force tends to press the slidable member 36 downwards onto the slide 37 and reduces vibration during operation of the machine. The locked screw 55 is initially fixed on setting up the machine and in normal circumstances is not readjusted.

On change of the plate roller 34 requiring a change of the position of the slidable member 36 it is necessary to change the bar stop member 57 for another member 57 of the requisite length when the piston rod 46 is in a retracted position. This may be carried out by election of the required bar stop member 57 from a separate store but preferably, as illustrated particularly with reference to FIG. 6, a series of bar stop members 57 of varying sizes to accommodate possible changes of the plate roller 34 are mounted at spaced intervals on a semi-rigid band 58 of polypropylene formed into a semi-rigid loop. All that is required on change of the plate cylinder is to lift the bar stop member 57 to be replaced out of the groove in the rod 51, thread the band 58 through the space between the

rods

50, 51 until the required bar stop member 57 is located and then fit it into the groove of the rod 51 in line with the

abutments

54, 56. By this means, the selection of the required bar stop member 57 is facilitated and mislaying of a required member 57 is obviated.

A convenient diameter for the bar stop member 57 is 75 inch and for a series of twenty-four members 57 suitably spaced on the band 58, the band 58 will have a diameter of about inches.

It will be appreciated that apparatus illustrated in FIGS. 5 and 6 is repeated on the other side of the machine in relation to the other slidable member 36.

Similarly, the apparatus illustrated in FIGS. 5 and 6 is repeated in respect of the second slidable members 40 associated with hydraulic cylinders 47 and like parts are identified with like numerals in FIG. 4. By these means, on replacement of the plate roller 34 the new position of the transfer cylinder 38 is readily fixed by selecting the bar stop member 57 of required size from the series on the band 58.

Referring to FIG. 7, the slidable member 36 as in FIG. 5 is capable of sliding in a slide 37 in the frame 33 under the influence of a hydraulic cylinder 44 with piston rod 46 mounted to an upright member 45 of the frame 33. Below and parallel with the piston rod 46 is an abutment rod 60 which is secured at one end to the slidable member 36 and passes freely through a hole (not shown) in the upright member 45. The rod 60 is terminated by a shaped abutment 61.

Secured to the upright member 45 and laterally spaced from the rod 60 is a rotatable turret 62 mounted in a housing 63. The turret 62 as shown more clearly in FIG. '8 is fitted with bar stop members 64 of selected sizes arranged in a circle about the axis of rotation and directed rearwardly in the direction of the abutment 61. For clarity only thee members 64 are illustrated in FIG. 8.

As shown in FIG. 9, the abutment 61 is so shaped that on movement of the rod due to the slidable member 36 being moved by a forward motion of the piston rod 46, it is capable of engaging one member 64 which has been brought into alignment with the abutment 61 by selected rotation of the turret 62. The location of the selected bar stop member 64 is made positive by a ball catch 65 fitted to the turret 62 which engages grooves 66 in the inner surface of the housing 63. For a final critical setting of the position of the bar stop members 64 the rear of the turret 62 abuts a screw member 67 threaded with the housing 63 and fitted with an operating handle 68. This screw member 67 is limited to a rotational arc of about and has a forward/backward movement of about 0.021 inch for final critical setting of the position of the bar stop members 64.

In operation, with the slidable member 36 in the retracted position the abutment 61 stands clear of the bar stop members 64 as shown in FIGS. 7 and 8. The member 64 selected for the particular plate roller 34 is then brought into alignment with the abutment 61 by rotation of the turret 62. On operation of the hydraulic cylinder 44, the piston rod 46 moves the slidable member 36 with plate roller 34 towards the impression cylinder 31. The rod 60 moves with the slidable member 36 until the abutment 61 meets the selected bar stop member 64 as illustrated in outline in FIG. 8. This arrests the forward motion of the slidable member 37 with the plate roller 34 placed precisely in position with respect to the impression cylinder 31. Any final critical setting may then be made by means of the screw member 67.

Since the pressure by the hydraulic cylinder 44 continues to be exerted, the resultant moment of force through the piston rod 46 and the rod 60 presses the slidable member 36 down into the slide 37 and this reduces vibration.

If the plate roller 34 is withdrawn from the impression cylinder 31 for a temporary stoppage, the parts are readily and precisely placed back into position on reoperation of the hydraulic cylinder 44. If the plate roller 34 is replaced by a different sized roller 34, by selecting the appropriate bar stop member 64, the new roller 34 is precisely placed with the minimum loss of operating time.

Whereas the turret 62 as described is fitted with fifteen bar stop members it will be understood that any number of suitably sized members may be used as is convenient to the machine and the range of plate rollers 34 to be used.

Further, if necessary the turret 62 may readily be replaced by a new turret 62 carrying a further series of bar stop members 64 of differing sizes, for example when a printing machine has dual pitch gearing.

It will be appreciated that apparatus shown in FIGS. 7, 8 and 9 is repeated on the other side of the machine in relation to the other slidable member 36. Similarly, the apparatus illustrated in FIGS. 7, 8 and 9 is repeated in respect of the second slidable members to associate with the hydraulic cylinders 47. Here, the cylinders 47 and the turrets 62 are mounted to upright members 48 on the slidable members 36.

It will be further appreciated that the rotatable turret 62 may be constructed in cylindrical form to permit the passage through its centre of the rod 60.

The screw members 67 may be operated by remote control by means not shown.

Any means for remote control of the screw member may be employed, for example each screw member may be operated by a reversible electric motor, through suitable gearing if necessary, controlled by a controller at the remote position.

In another form of remote control, the screw member may be fitted with a helical gear or part of a helical gear covering the desired rotational arc of the screw member and at one side of the gear is a cooperating helical pinion mounted upon a piston rod and capable of being thrust in or out of mesh with the teeth of the helical gear. The helical pinion is fitted with a free-wheel device whereby upon a forward thrust to engage the helical gear it is fixed in the direction of rotation in which the meshing of the teeth tends to drive it and as a consequence the helical gear is caused to rotate through a small arc. On retraction from the meshing position, the helical pinion freely rotates in the opposite direction and imparts no drive to the helical gear.

A second helical pinion mounted similarly upon a second piston rod is positioned at the other side of the helical gear and being constructed similarly to the first helical pinion is capable of being thrust into mesh with the helical gear to rotate the helical gear through a small arc in a direction opposite to that caused by the first helical pinion.

The piston rods may each be reciprotated by hdraulic, pneumatic or electrical means when operated from the remote operating position. By these means, the operator while viewing the printed image, can rotate the helical screw and thus the screw member either clockwise or anti-clockwise step-wise through small discrete increments of arc to effect a final critical setting of the plate and transfer rollers. Movement of the rollers by increments of the order of 0.0004 inch may readily be obtained.

Alternatively, the helical pinion and helical gear may be replaced by a Hersch clutch.

Alternatively, in still another form, each screw mem' ber may be fitted with a click-stop mechanism, for example a ball catch which engages grooves set at suitable spaced intervals around the screw member, and the screw member is rotated a stop at a time either clockwise or anti-clockwise by a solenoid, pneumatic or hydraulic operated ratchet and pawl mechanism under the influence of electric, pneumatic or hydraulic impulses initiated from the remote position.

We claim:

1. A printing machine comprising a frame, an impression cylinder rotatably mounted with said frame, and at least one printing station comprising a first pair of spaced apart slidable members carried by said frame and a plate roller mounted at each end thereof to a respective one of said first pair of slidable members and movable therewith towards and away from the impression cylinder, first urging means acting upon each of said first pair of slidable members for urging the respective end of the plate roller towards the impression roller, first replaceable stop means of non-adjustable predetermined size associated with said frame and each of said first pair of slidable members so as to limit the movement of each end of the plate roller towards the imprssion cylinder at substantially the operative position for the plate roller, a second spaced apart pair of slidable members carried respectively by the first pair of slidable members, a transfer roller mounted at each end thereof to a respective one of said first pair of slidable members and therewith towards and away from the plate roller, second urging means acting on each second slidable member for urging each end of the transfer roller towards to plate roller, second replaceable stop means of non-adjustable predetermined size associated with said first pair of slidable members and said second pair of slidable members so as to limit the movement of each end of said transfer roller towards the plate roller at substantially the operative position for said transfer roller.

2. A printing machine according to claim 1 wherein said urging means are fluid operated cylinders.

3. A printing machine according to claim 1 in which each first replaceable stop member lies between a first abutment connected in fixed relationship to a bearing for an end of the plate roller and a first counter abutment connected in fixed relationship to a bearing for a corresponding end of the impression cylinder, and each second replaceable stop member lies between a second abutment connection in fixed relationship to a bearing for an end of the transfer roller and a second counter abutment connected in fixed relationship to a bearing for a corresponding end of the plate roller.

4-. A printing machine according to claim 3 wherein at least one of said pair of said abutment and counter abutment is a screw member to provide fine adjustment for the operative positions of the plate and transfer rollers.

5. A printing machine as claimed in claim 4, in which each screw member adjusts the position of a counter abutment.

6. A printing machine as claimed in claim 4, in which each screw member is operated by remote control.

7. A printing machine as claimed in claim 4, in which the screw member is arranged for step-wise movement through discrete increments of are.

8. A printing machine as claimed in claim 3, in which the first and second abutments are mounted on rods carried by the first and second slidable members respectively and extending in a direction away from the impression cylinder.

9. A printing machine as claimed] in claim 8 in which the urging means for the plate roller and the transfer roller are fluid operated cylinders, and the rod carrying the first abutment is a rearwardly extending portion of a piston rod of an operating cylinder mounted in fixed relationship to the frame member, and the rod carrying the second abutment is a rearwardly extending portion of a piston rod of an operating cylinder mounted in fixed relationship to a second slidable member.

110. A printing machine as claimed in claim 8, in which each replaceable stop member is a tube fitted over the rearwardly extending portion of the rod, and the respective abutment is a releasable fastener of a size larger than the bore of the tube for retaining the tube on the rod and for arresting the forward motion of the rod when the tube is trapped between the fastener and the counter abutment.

11. A printing machine as claimed in claim 1, in which each replaceable stop member is a bar of preselected length, arranged to extend in the direction of travel of the respective slidable member and to limit its forward movement by engagement of one end of the bar with a relatively moving abutment.

12. A printing machine as claimed in claim 11, in which a plurality of bars of different preselected lengths are provided on a carrier adapted to allow indi- Ill vidual bars to be slectively brought into an operative position.

13. A printing machine according to claim 12, in which the carrier comprises a turret rotatably mounted to the machine so that on rotation thereof any selected bar can be brought to the operative position.

14. A printing machine according to claim 12 wherein the carrier is a band to which the bars are secured.

15. A printing machine according to claim 14 wherein the band is in the form of a semi-rigid closed loop.

16. In combination with a rotary printing press having slidable frame means for rotatably supporting a removable printing plate cylinder, and a co-operating cylinder of the press and enabling relative reciprocation therebetween in a direction generally perpendicular the rotational axis thereof, a set of at least two printing plate cylinders of different diameters for selective operative association with said frame means and said cooperating cylinder, means connected with said frame means for selectively urging said co-operating cylinder and the selected operative one of said set of printing plate cylinders toward each other, and a set of selectively operable stop members correlated with said set of printing press cylinders selectively operable to limit the reciprocation and define the operative spacing between said cylinders to the correct spacing for the selected one of said set of printing plate cylinders.

17. Combination defined in claim 16 wherein said frame means comprises a first pair of spaced apart frame members for rotatably supporting the ends of the selected one of said set of printing plate cylinders and a second pair of spaced apart frame members for rotatably supporting the ends of said co-operating cylinders operatively structurally associated with a respective one of said first set of frame members for relative slidable movement therebetween enabling radial relative movement between said cylinders.

18. Combination defined in claim 17 wherein said urging means comprise a pair of fluid operated cylinders connected between each respective set of associated frame members.

19. Combination defined in claim 18 further comprises an opposed set of abutment means carried respectively by each of said frame members for selective disposition of a selected stop member therebetween, and at least one abutment means of each opposed set being provided with adjustment means for enabling minor operating adjustment of the relative position of said cylinders.

Claims

1. A printing machine comprising a frame, an impression cylinder rotatably mounted with said frame, and at least one printing station comprising a first pair of spaced apart slidable members carried by said frame and a plate roller mounted at each end thereof to a respective one of said first pair of slidable members and movable therewith towards and away from the impression cylinder, first urgiNg means acting upon each of said first pair of slidable members for urging the respective end of the plate roller towards the impression roller, first replaceable stop means of non-adjustable predetermined size associated with said frame and each of said first pair of slidable members so as to limit the movement of each end of the plate roller towards the imprssion cylinder at substantially the operative position for the plate roller, a second spaced apart pair of slidable members carried respectively by the first pair of slidable members, a transfer roller mounted at each end thereof to a respective one of said first pair of slidable members and therewith towards and away from the plate roller, second urging means acting on each second slidable member for urging each end of the transfer roller towards to plate roller, second replaceable stop means of nonadjustable predetermined size associated with said first pair of slidable members and said second pair of slidable members so as to limit the movement of each end of said transfer roller towards the plate roller at substantially the operative position for said transfer roller.

4. A printing machine according to claim 3 wherein at least one of said pair of said abutment and counter abutment is a screw member to provide fine adjustment for the operative positions of the plate and transfer rollers.

7. A printing machine as claimed in claim 4, in which the screw member is arranged for step-wise movement through discrete increments of arc.

9. A printing machine as claimed in claim 8 in which the urging means for the plate roller and the transfer roller are fluid operated cylinders, and the rod carrying the first abutment is a rearwardly extending portion of a piston rod of an operating cylinder mounted in fixed relationship to the frame member, and the rod carrying the second abutment is a rearwardly extending portion of a piston rod of an operating cylinder mounted in fixed relationship to a second slidable member.

10. A printing machine as claimed in claim 8, in which each replaceable stop member is a tube fitted over the rearwardly extending portion of the rod, and the respective abutment is a releasable fastener of a size larger than the bore of the tube for retaining the tube on the rod and for arresting the forward motion of the rod when the tube is trapped between the fastener and the counter abutment.

12. A printing machine as claimed in claim 11, in which a plurality of bars of different preselected lengths are provided on a carrier adapted to allow individual bars to be sleCtively brought into an operative position.

16. In combination with a rotary printing press having slidable frame means for rotatably supporting a removable printing plate cylinder, and a co-operating cylinder of the press and enabling relative reciprocation therebetween in a direction generally perpendicular the rotational axis thereof, a set of at least two printing plate cylinders of different diameters for selective operative association with said frame means and said co-operating cylinder, means connected with said frame means for selectively urging said co-operating cylinder and the selected operative one of said set of printing plate cylinders toward each other, and a set of selectively operable stop members correlated with said set of printing press cylinders selectively operable to limit the reciprocation and define the operative spacing between said cylinders to the correct spacing for the selected one of said set of printing plate cylinders.