GB2042423A

GB2042423A - Roller actuating mechanism

Info

Publication number: GB2042423A
Application number: GB8004166A
Authority: GB
Original assignee: Dahlgren Manufacturing Co Inc
Current assignee: Dahlgren Manufacturing Co Inc
Priority date: 1979-02-16
Filing date: 1980-02-07
Publication date: 1980-09-24
Also published as: IT1175391B; FR2448978A1; DE3005664A1; JPS55113566A; DD149187A5; IT8009353A0; SE8000942L

Abstract

A roller actuating mechanism for use in a device wherein liquid is metered between a first roller 60 and, a second roller 50 which rotate at different peripheral speeds wherein the actuating means moves one roller relative to the other between a first position where pressure is applied to meter liquid eg damping liquid in a printing press, and a second position wherein pressure is relieved to allow slippage between the roller surfaces without damage but still effect some controlling effect on the liquid. The actuating mechanism comprises actuating arms 30a, 30b supporting the first roller 60 and hangers 25a, 25b supporting the second roller 50, the actuating arms and the hangers being pivotally connected for limited relative movement to increase pressure between the contacting surfaces of the rollers 60, 50 when the actuating arms are swung in one direction and to reduce the pressure between the rollers 60, 50 when the arms are swung in the opposite direction. A skewing adjustment may also be provided. <IMAGE>

Description

SPECIFICATION Roller actuating mechanism A number of devices are already known which employ rollers urged into pressure indented relation and driven at different surface speeds to form a film of liquid of controlled thickness on the surface of one of the rollers. Examples are disclosed in United States Patent No.

3,343,484, entitled LITHOGRAPHIC DAMP ENER WITH SKEWED METERING ROLLER; United States Patent No. 3,647,525, entitled METHOD AND MEANS FOR APPLYING LIQ UID TO A MOVING WEB; United States Patent No. 3,937,141, entitled DAMPENER FOR LITHOGRAPHIC PRINTING PLATES; United States Patent No. 3,986,452, entitled LIQUID APPLICATOR FOR LITHOGRAPHIC SYSTEMS; and United States Patent No.

4,041,864, entitled METHOD AND APPA RATUS FOR INKING PRINTING PLATES.

Heretofore, it has been standard procedure, for pressmen operating dampeners of the type disclosed in United States Patent No.

3,343,484, to establish pressure between a metering roller and a transfer roller to form a film of the required thickness for application over one or more form rollers to the surface ol a lithographic printing plate. The metering roller and the transfer roller in such systems are often mounted in a common frame as disclosed in United States Patent No.

3,1 68,037 to assure that the pressure between adjacent surfaces of the metering roller and the transfer roller will not be disturbed when the transfer roller is moved into and out of engagement with the surface of a form roller.

Generally, at least one of the metering and transfer rollers has been furnished with a resilient surface which is indented by the surface of the other roller. It has been recommended by the manufacturer of such equipment that the surfaces of the metering and transfer rollers should be moved out of engagement when the dampening system is not being operated, to prevent the forming of a flat line on the surface of the resilient surface roller, which might occur if left significantly indented for an extended period of time. How ever, pressmen, knowing that it will be necessary to re-establish the pressure relationship between the rollers to prepare the press for printing, are sometimes hesitant to disturb the pressure adjustment.

Further, the surfaces of the metering and transfer rollers usually move at different surface speeds to accomplish metering of films o the desired thickness. When operating, dampening fluid is spread over the surfaces of the metering and transfer rollers and the liquid functions as a lubricant to maintain hydraulic separation between the surfaces which are moving at different surface speeds. However, when such systems are being made ready for operation, the surfaces of the metering roller and the transfer roller are generally dry and the lubricating layer of dampening fluid is not present. The dry surfaces of the rollers may tend to stick together due to increased friction, resulting in damage to the surface of the resilient surfaced roller. Slippage between the dry surfaces may, also, scuff or otherwise damage the resilient surfaced roller.In addition, in some instances, damage to the mechanical and electrical drive systems have resulted when attempting to cause the dry heavily-indented surfaces of the rollers to slip over one another.

If the metering roller and the transfer roller are driven to wet the metering roller while the surfaces of the metering roller and the transfer roller are widely separated, an excessively thick film of liquid on the metering roller surface will be "dumped" into the system when the dampener is actuated "on" or "offimpression". This may result in web breaks or creation of an inbalance of ink and dampening fluid in the printing system.

An object of the present invention is to provide an improved roller actuating mechanism which is particularly adapted to permit adjustment of two or more rollers to establish a desired pressure or stripe between adjacent surfaces of the rollers when in an operative or "on-impression" position and automatically to reduce the pressure or stripe between the rollers when moved to an inoperative or "offimpression" position, and, when in the inoperative position, the surfaces of the rollers are not separated or are only separated slightly to maintain reasonable control of a liquid film thickness, such an arrangement permitting rotation of the rollers, when dry, without damage to the resilient surfaced roller while, also, allowing movement of dampening fluid by the surface of one of the rollers to the nip between the metering and transfer rollers to maintain a reasonable control of the liquid;; when the transfer roller is thrown to an operative or "on-impression" position, in engagement with a form roller, the pressure between the metering roller and the transfer roller will be automatically increased to the pre-established condition.

Another object of the invention is to provide a roller actuating mechanism particularly adapted to reduce nip pressure between a metering roller and a transfer roller when moved to an inoperative position and to reestablish a previously set nip pressure when the rollers are moved to an operative position.

A further object of the invention is to provide a roller actuating mechanism adapted to permit adjustment of pressure or limited separation between surfaces of a metering roller and a transfer roller when in an "off-impression" position to permit driving the rollers at different surface speeds, while dry, without damage to the rollers while, also, having the capability of transferring a lubricating liquid on the surface of one of the rollers to the nip between the rollers without slinging liquid from surfaces of the rollers or causing an excessive undesirable surface of liquid into related rollers or devices when actuated to the "on-impression" position.

A still further object of the invention is to provide a roller actuating mechanism to move a pair of rollers between a position wherein axes of the rollers are parallel and a position wherein the rollers are skewed while one of the rollers is being actuated to or from an "on-impression" position.

With this object in view, the present invention provides a device to meter liquid at a nip between adjacent surfaces on a first roller and a second roller adapted to be driven at different peripheral speeds such that slippage occurs at the nip, comprising means to apply liquid to a surface of one of the rollers such that liquid will be moved by the roller surface to the nip, and actuating means to move one of the rollers relative to the other roller between a first position wherein contact pressure is applied at the nip adjacent ends of the rollers to meter liquid at the nip and a second position wherein one of the rollers is positioned relative to the other roller to permit slippage between dry surfaces on the rollers without damage to the roller surfaces while controlling liquid carried through the nip.

The roller actuating mechanism is adaptable for use in a variety of devices wherein liquid is metered between first and second rollers, at least one of which has a resilient cover, urged into pressure indented relation. In a specific embodiment of the invention, the mechanism generally comprises a metering roller hanger or skew actuating arm pivotally secured to a press or dampener sideframe and a transfer roller actuating arm pivotally secured to the metering roller hanger or the skew actuating arm. The metering roller hanger has a passage or track formed therein and the transfer roller actuating arm has a lug extending into the track to permit limited movement of the actuating arm relative to the hanger when the actuating arm is moved, or the reverse configuration can apply.When the actuating arm rotates relative to the metering roller hanger, the distance between the axes of the metering roller and the transfer roller will be changed.

A stop is movably secured in the passage in the hanger such that movement of the actuating arm and consequently the change in pressure between the metering roller and the transfer roller or the limited separation between the metering roller and the transfer roller can be controlled to result in an operable "off-impression" condition.

The transfer roller and a form roller are connected by an actuating link so that a single actuating cylinder will move the transfer roller out of pressure indented relation with the form roller and cause the actuating arm to be rotated relative to the hanger for reducing pressure between the metering roller and the transfer roller.

In a second embodiment of the roller actuating mechanism, a metering roller hanger, a transfer roller actuating arm, and a skew arm are arranged such that pressure adjacent ends of the rollers is changed and an end of one of the rollers is moved about the end of the other roller to further change pressure intermediate opposite ends of :the rollers.

The invention will be described further, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a diagrammatic fragmentary elevation showing a first embodiment of the roller actuating mechanism of the invention, associated with rollers in a printing press, the view being taken as indicated by the line 1-1 of Fig. 2; Figure 2 is an enlarged cross-sectional view taken along line 2-2 of Fig. 1; Figure 3 is a cross-sectional view taken along line 3-3 of Fig. 2; Figure 4 is a cross-sectional view taken along line 4-4 of Fig. 2; Figure 5 is an enlarged cross-sectional view taken along line 5-5 of Fig. 3; Figure 6 is a diagram showing the rollers of the arrangement of Figs. 1 to 5 in the "offimpression" position; Figure 7 is a diagram similar to Fig. 6 but showing the rollers in an "on-impression" position;; Figure 8 is a cross-sectional view similar to Fig. 4, but showing a second embodiment of the roller actuating mechanism of the invention in an "on-impression" position; Figure 9 is a cross-sectional view taken along line 9-9 of Fig. 8; Figure 10 is a cross-sectional view similar to Fig. 8 with the roller actuating mechanism in an "off-impression" position; and Figure 11 is a cross-sectional view taken along line 11-11 of Fig. 10.

Numeral references employed in Figs. 8 to 11 to designate parts similar to those of Figs.

1 to 7 of the drawings have been allocated the same numerals in Figs. 1 to 7 but increased by 100.

Referring firstly to Fig. 1, the numeral 10 generally designates a printing press including a printing plate cylinder P and a blanket cylinder B rotatably supported between press sideframes 11 and 1 2.

As will be hereinafter more fully explained, form rollers 14 and 1 5 are urged into pressure indented relation with the printing plate cylinder P and with a vibrator roller 1 6. An ink supply roller 1 8 delivers ink to the vibrator roller 1 6 which in turn applies the ink to the form rollers 1 4 and 1 5 for inking a printing plate on the plate cylinder P.

The improved roller actuating mechanism is embodied in the dampener, generally designated by the numeral 20, and comprises metering roller hangers 25a and 25b mounted for limited pivotal movement relative to transfer roller actuating arms 30a and 30b, respectively.

As will be hereinafter more fully explained, a form roller actuating link 70 is pivotally secured relative to each transfer roller actuating arm 30a and 30b for moving the form roller 14 into and out of pressure indented relation with a printing plate on the plate cylinder P.

Referring to Fig. 2, dampener sideframe 21 is bolted or otherwise secured to the printing press sideframe 11 on the drive side of the printing press and a dampener sideframe 22 is bolted or otherwise secured to the sideframe 1 2 on the operator side of the printing press 10.

The metering roller hanger 25a on the drive side of the press is pivotally secured relative to the dampener sideframe 21 and the press sideframe 11 by a stub shaft 26 which extends into a socket 27 formed adjacent one end of the metering roller hanger 25a.

The metering roller hanger 25 on the operator side is pivotally secured to the dampener sideframe 22 and the press sideframe 1 2 by a respective stub shaft 26 extending into a socket 27b formed in an end of a skew arm 28. The hanger 25b is pivotally secured to the skew arm 28 by a hollow bushing 29 extending through aligned openings formed in the skew arm 28 and the metering roller hanger 25b.

As is best illustrated in Figs. 3 and 5, the transfer roller actuating arm 30a adjacent the drive side of the printing press 10 is pivotally secured to the metering roller hanger 25a by a pivot pin 32a having one end secured, as by being a shrink fit, in an aperture formed in the metering roller hanger 25a. The other end of the pin 32a is rotatably disposed in a bushing 33a in an opening formed in the actuating arm 30a.

An elongate passage 35a is formed in the metering roller hanger 25a at a position spaced from the pivot pin 32a and forms a track along which a lug 40a is movable. The lug 40a is rigidly secured by a cap screw 42 to the actuating arm 30a and forms a follower which is movable through the passage 35a.

End 36a of the passage 35a limits movement of the lug 40a through the passage 35a in one direction.

A screw 37a is threadedly secured through an opening formed in the metering roller hanger 25a and has an end 38a which extends into the passage 35a. A lock nut 39a is employed for the securing screw 37a in a preestablished position.

It should be readily apparent that the end 38a of the screw 37a extends into the passage 35a to serve as a stop such that the distance between the end 36a of the passage 35a and the end 38a of the screw 37a is adjustable to permit limited movement of the lug 40a longitudinally in the elongate passage 35a as will be hereinafter more fully explained.

As best illustrated in Figs. 2 and 4, transfer roller actuating arm 30b adjacent sideframe 1 2 on the operator side of the printing press is pivotally secured to the skew arm 28.

However, it will be observed that elongate passage 35b is formed in the skew arm 28 rather than through the hanger 25b. Lug 40b is secured to the actuating arm 30b and the distance which it is movable long the passage 35b is adjustable by set screw 37b.

The transfer roller actuating arm 30b on the operator side of the printing press is pivotally secured by a pin 326 two the skew arm 28 in the same manner as the actuating arm 30a is pivotally secured to the metering roller hanger 25a on the drive side of the press as above described in relation to Fig. 5.

As is best illustrated in Figs. 2, 3 and 4, the mechanism comprises a pressure actuated cylinder 45 having a piston (not shown) slidably disposed therein and having therein an extensible rod 46 which is pivotally secured by a clevis pin 47 to its transfer roller actuating arm 30a or 30b. The cylinder 45 is pivotally secured by a bolt 48 to a mounting plate 49 bolted or otherwise secured to the press sideframe 11 or 1 2.

As is best illustrated in Figs. 2, 3 and 4, metering roller 50 has, on opposite ends thereof, journals 50a and SOb which are rotatably disposed in self-aligning bearings 52 supported by blocks 54 movable along guideways 24 formed in the metering roller hangers 25a and 25b. Each of the slide block 54 is resiliently urged by a spring 23 into engagement with the end of a metering roller pressure adjustment screw 55. The metering roller adjustment screw 55 is positioned to move its block 54 longitudinally through its guideway 24.

Transfer roller 60 has on opposite ends thereof journals 60a and 60b which are rotatably disposed in self-aligning bearings 62 mounted in bearing housings 64a and 64b which are bolted or otherwise secured to the transfer roller actuating arms 30a and 30b, respectively. A peripheral clearance relationship 69a with the metering roll hanger 25a, and a peripheral clearance relationship 69b with the hollow bushing 29, allow the distance between the axes of the transfer roller 60 and the metering roller 50 to be changed.

Each bearing housing 64a and 63b is split and has a bearing cap 65 bolted or otherwise secured thereto, as is best illustrated in Fig. 3, to facilitate installation of bearings 62.

The form roller actuating links 70 have, in their outer ends, slotted openings 72 through which extend form roll actuation pins 71 secured into form roll hangers 76a and 76b.

Each form roller actuating link 70 has an elongate slot 74 formed in a central portion thereof, and a form roller adjustment screw 75 extending into each slot 74 and in threaded engagement with pins 67a and 67b which are pivotally secured into the transfer roll bearing housings 64a and 64b, respectively, and positioned such that the centrelines of the pins 67a and 67b are in linear relationship with the centrelines of the transfer roll journals 60a and 60b for adjustment of the pressure at the nip between the transfer roller 60 and the form roller 14, as will be hereinafter more fully explained.

As is best illustrated in Figs. 1, 3 and 4, journals 1 4a and 1 4b on opposite ends of the form roller 1 4 are rotatably disposed in bearings (not shown) mounted in eccentric bearing housings (not shown) which are adjustably secured in the form roller hangers 76a and 76b which are suspended from and pivot about journal bearings 1 7a and 1 7b of journals 1 6a and 1 6b on the ends of the vibrator roller 16. This vibrator roller 16 is supported by the bearings 1 7a and 1 7b for oscillatory movement in a direction parallel to the axis of the roller 1 6 while in rotative contact with the ink supply roller 1 8 and the form rollers 1 4 and 15.

A plate pressure adjustment screw 78 is pivotally secured by a pin 73 to the form roller hangers 76a and 76b. The adjustment screw 78 has spaced nuts 77 and 79 mounted thereon at opposite sides of a stop 80 having a central aperture through which the end of the screw 78 extends. The stop 80 is pivotally secured to the dampener sideframes 21 and 22.

As is best illustrated in Figs. 2 and 4, the metering roll hanger 25b has an outwardly extending projection 84 pivotally secured by a pin 87 to the end of a skew adjustment screw 85. This skew adjustment screw 85 threadedly engages a block 86 which is pivotally secured to an outwardly extending projection 88 from the skew arm 28 on the operator side of the press.

As is best illustrated in Fig. 2, a pan 90 is positioned adjacent the metering roller 50 such that the surface on the metering roller 50 extends into liquid in the pan 90 to wet the surface of the metering roller 50.

A second embodiment of the roller actuating mechanism is illustrated in Figs. 8 to 11 of the drawings. The apparatus illustrated in these figures differs from the first embodiment illustrated in Figs. 1 to 7, primarily, in that extensible rod 146 on pressure actuated cylinder 145 is secured by a pin 147 to metering roller hanger 1 25b. Thus, when the metering roller hanger 1 25b is actuated from the "onimpression" position illustrated in Fig. 8, the metering roller hanger 1 25b moves relative skew arm 1 28 to the position illustrated in Fig. 10 in an "off-impression" position.

Further, in the embodiment as illustrated in Figs. 8 to 10, skew adjustment screw 185 has been relocated to permit limited movement of the metering roller hanger 1 25b relative to the skew arm 1 28. Otherwise, the structure is substantially the same as that illustrated in Fig. 4 of the drawing.

Referring to Figs. 8 and 9, the pressure actuated cylinder 145 is pivotally secured by a bolt 148 to a mounting plate 149 bolted or otherwise secured to sideframe 12.

The extensible rod 146 is pivotally secured by the clevis pin 147 to the metering roller hanger 1 25 b having bearing block 1 54 supporting self-aligning bearing 1 52 in which the metering roller 50 is rotatably supported.

A hollow bushing 1 29 extends through aligned openings in the metering roller hanger 125b and in the skew arm 128, the lower end of the skew arm 1 28 being pivotally secured by a stub shaft 126boo press sideframe 12.

Transfer roller actuating arm 1 30b is pivotally secured by a pivot pin 1 32b to the skew arm 1 28. The actuating arm 1 30b has bolted or otherwise secured thereto a bearing housing 1 64a which supports a self-aligning bearing 1 62 in which the journal on the end of transfer roller 60 is rotatably disposed. It will be appreciated that hollow bushing 1 29 has formed therein an enlarged central opening through which the bearing housing 1 64a extends to permit movement of the rotational axis 60' of the transfer roller 60 relative to the rotational axis 50' of the metering roller 50.

The skew arm 1 28 has an elongate passage 1 35b into which extends lug 1 40b secured to the actuating arm 1 30b. Adjusting screw 1 37a is threadedly secured to the skew arm 1 28 to limit movement of the lug 1 40b along the passage 1 3 5 b.

The skew adjustment screw 1 85 is slidably disposed through a block 1 86 pivotally secured to the transfer roller actuating arm 1 30b and is threadedly secured to a block 1 84 which is pivotally secured by a pin 1 87 to the metering roller hanger 1 25b.

As the metering roller hanger 1 25b moves from the position illustrated in Fig. 8 to the position illustrated in Fig. 10, the skew adjustment screw 1 85 slides through a passage in the block 1 86 to permit limited relative movement between the metering roller hanger 1 25b and the skew arm 1 28. When the block 1 84 engages the block 186, the transfer roller actuating arm 1 30b and the metering roller hanger 1 25 b will move in unison to position the lug 1 40b in engagement with the end of the adjustment screw 1 37a.

The operation of the first above described embodiment can best be understood with reference to Figs. 1, 3 and 4, and is as follows: While the rod 46 of the cylinder 45 is extended, the metering roller 50 will be urged into pressure indented relation with the transfer roller 60 which, in turn, is urged into pressure indented relation with the form roller 14 which, in turn, is urged into pressure indented relation with a printing plate on the plate cylinder P.

The nut 79 on the pressure plate adjustment screw 78 is adjusted to provide a desired pressure or stripe at the nip 100 between the form roller 14 and the printing plate on the plate cylinder P.

The form roller pressure adjustment screw 75 on the form roller actuating link 70 can then be rotated for adjusting the pressure at the nip 102 between the transfer roller 60 and the form roller 1 4 utilizing thrust of the end of the slotted openings 72 against the acuation pins 71.

The metering roller pressure adjustment screw 55 is rotated for moving the slide block 54 longitudinally through the guideway 24 for adjusting pressure at the nip 104 between the metering roller 50 and the transfer roller 60.

To adjust the pressure intermediate the opposite ends of the metering roller 50 and transfer roller 60, the skew adjustment screw 85 is rotated for moving the end of one of the rollers 50 or 60 circumferentially about the axis of the other roller.

After dampening fluid has been placed in the pan 90 and pressure has been established at the nips 100, 102 and 104, the dampener 20 is ready for operation.

When the rod 46 in the pressure actuated cylinder 45 is retracted, the transfer roller actuating arms 30a and 30b will rotate about the pins 32a and 32b, respectively, thereby moving the transfer roller 60 vertically, as illustrated in the drawing, and increasing the distance between the axis of the metering roller 50 and the axis of the transfer roller 60.

This reduces the pressure at the nip between the metering roller 50 and the transfer roller 60.

Rotation of the adjustment screws 37a and 37b will move the surface of the transfer roller 60 into pressure indented relation with the surface of the metering roller 50.

Thus, the position of the ends 38a and 38b of the screws 37a and 37b establishes and maintains a reduced pressure between the metering roller 50 and the transfer roller 60 or establishes and maintains a controlled separation to allow a control of a liquid passing between the metering roller 50 and the transfer roller 60 when the rollers are moved to an inoperative or "off-impression" position. It is important that the surfaces of rollers 50 and 60 are maintained in light engagement or controlled separation to prevent slinging of dampening fluid when the dampener drive motors are engaged. Dampening fluid carried by the surface of the roller 50 to the nip 104 will be metered to form a relatively thin film of dampening fluid on the surface of the transfer roller 60.It will be appreciated that gear 66 secured to the journal 50a of the metering roller 50 is larger in diameter than gear 68 secured to the journal 60a on the transfer roller 60. Therefore, under normal operating conditions, the metering roller 50 will rotate at a surface speed substantially less than the surface speed of the transfer roller 60. The metering roller 50 might move, for example, at a surface speed of 30 metres (100 feet) per minute while the surface of transfer roller 60 might move at a speed of, for example, 60 metres (200 feet) per minute.

The adjustment of the screws 37a and 37b to maintain the surface of the rollers 50 and 60 in light engagement or controlled separation permits rotation of the rollers at different surface speeds to transfer a film of dampening fluid to the nip 104 without damaging the resilient surface on the metering roller 50.

After a lubricating layer of dampening fluid has moved to the nip 104, the rod 46 of the pressure actuated cylinder 45 can be extended which causes movement of the lugs 40a and 40b toward the ends 36 of the passage 35 to establish the pressure necessary for printing.

When the rod 46 of the pressure actuated cylinder 45 is retracted, the nut 77 can be adjusted on the plate pressure adjustment screw 78 to control the position of the form roller 14 when in an "off-impression" position. It should be readily apparent that movement of the journals 1 4a and 1 4b in the slotted openings 72 in the form roller actuating link 70 will cause separation of the surfaces between the transfer roller 60 and the form roller 1 4 when the rod 46 of the pressure actuated cylinder 45 is retracted.

The positions of the form roller 14, the transfer roller 60 and the metering roller 50 in the "on-impression" position are illustrated in Fig. 6, while the positions of the rollers in the "off-impression" position are illustrated in Fig. 7.

As hereinbefore described in the description of the second embodiment, the operation of the mechanism illustrated in Figs. 8 to 11 is similar to that of the structure illustrated in Figs. 1 to 7 except that the metering roller hanger 1 25b pivots abouts its bushing 129 relative to the skew arm 1 28 to change the pressure intermediate the opposite ends of the rollers 50 and 60, and the skew arm 1 28 moves relative to the transfer roller actuating arm 1 30b to change pressure at the ends of the rollers 50 and 60.

It will readily be apparent that other and further embodiments of the invention may be devised without departing from the scope of the invention as defined by the following claims.

While the roller actuating mechanism has been specifically described in combination with rollers for use in a lithographic printing system, the roller actuating mechanism may be used in other devices, including devices for applying liquid to a web or for applying ink to a printing plate.

Claims

1. A device to meter liquid at a nip between adjacent surfaces on a first roller and a second roller adapted to be driven at different perhipheral speeds such that slippage occurs at the nip, comprising means to apply liquid to a surface of one of the rollers such that liquid will be moved by the roller surface to the nip, and actuating means to move one of the rollers relative to the other roller between a first position wherein contact pressure is applied at the nip adjacent ends of the rollers to meter liquid at the nip and a second position wherein one of the rollers is positioned relative to the other roller to permit slippage between dry surfaces on the rollers without damage to the roller surfaces while controlling liquid carried through the nip.

2. A device as claimed in claim 1, in which the actuating means is adapted to permit adjustment of pressure exerted at the nip when the rollers are in said first position without changing the relationship of the rollers when in said second position.

3. A device as claimed in claim 2 in which the actuating means is adapted to move an end of one of the rollers about an end of the other roller to change pressure at the nip between ends of the rollers as one of the rollers is moved between said first and second positions.

4. A device as claimed in claim 1, 2 or 3 in which at least one of the rollers has a resilient cover with which the other roller engages with pressure indented relation, wherein the first roller is carried by a hanger such that said first roller will rotate about a first axis, and the second roller is carried by an actuating arm such that said second riller will rotate about a second axis; there being means movably connecting the hanger to the actuating arm and limit means between the actuating arm and the hanger to permit limited movement of the actuating arm relative to the hanger to move the first and second rollers relative to each other between the first position and the second position, and means to move the actuating arm.

5. A device as claimed in claim 4, in which the hanger has an elongate track formed therein, there being stop means extending along said track; and means to adjust the distance between said stop means and an end of the track, the limit means comprising a lug on the actuating arm and movable along the track between the stop means and the end of the track.

6. A device as claimed in claim 4 or 5 wherein the first roller is carried by the hanger by way of means permitting adjustment of the spacing between the first and second axes.

7. A device as claimed in claim 4, in which the hanger has a guideway formed therein and wherein the first roller is secured to the hanger by means of a bearing block slidably mounted in said guideway, means being provided to move this bearing block along the guideway to change the distance between the axes of the first and second rollers.

8. A device as claimed in claim 4, in which the hanger is movably secured to a frame by means comprising; a skew arm; means pivotally securing said skew arm to the hanger such that the hanger pivots about an axis which is aligned with the second axis about which the second roller rotates; and means pivotally securing said skew arm to said frame such that the skew arm is pivotable about an axis which is aligned with the first axis about which the first roller rotates.

9. A device as claimed in claim 8, in which the means pivotally securing the skew arm to the hanger comprises a hollow bushing extending through openings in the skew arm and in the hanger, the hollow bushing having a central passage through which extends means to secure the second roller to said actuating arm.

10. A device as claimed in claim 9, in which the means to move the actuating arm comprises a pressure actuated cylinder having an extensible rod connected to the hanger, and means mounting this cylinder to said frame.

11. A device as claimed in any preceding claim wherein the first roller is a metering roller and the second roller is a transfer roller.

1 2. A device as claimed in claims 8 and 11 further including a form roller rotatably carried by a support pivotally secured to the frame, a form roller actuating link having in one end thereof an elongate slot through which an end of the form roller extends, and means pivotally securing the form roller actuating link relative to the actuating arm such that upon extension of the rod in the pressure actuated cylinder, the second roller moves into engagement with the form roller and the actuating arm pivots relative to the hanger to increase pressure between the surface of the first and second rollers.

1 3. A device as claimed in any of claims 4 to 1 2 in which the skew arm is so pivoted to the hanger that the hanger will pivot relative to the skew arm about an axis in line with said second axis to move an end of the first roller about an end of the second roller.

14. A device to meter liquid at a nip between confronting surfaces of a pair of rollers substantially as hereinbefore described with reference to and as illustrated in Figs. 1 to 7 or in Figs. 8 to 11 of the accompanying drawings.