GB1580079A

GB1580079A - Dampening liquid spraying device

Info

Publication number: GB1580079A
Application number: GB3205577A
Authority: GB
Original assignee: MAN Maschinenfabrik Augsburg Nuernberg AG
Current assignee: MAN AG
Priority date: 1976-07-31
Filing date: 1977-07-29
Publication date: 1980-11-26
Also published as: FR2360421B1; IT1079330B; DE2634555A1; SE416909B; DE2634555C3; CH620397A5; DE2634555B2; FR2360421A1; SE7708668L

Abstract

The damping-medium spraying device for damping a roller in an offset printing machine comprises a flinger roll (1) which rotates in a housing (4) about an axis running parallel to the offset printing machine rollers. The housing (4) has an outlet slot (8) which is bounded at the bottom by a covering plate (9). The flinger roll (1) has webs (2) which run radially outwards and enclose the flinger roll (1) at an inclination to a plane running vertically to the roll axis. The webs (2) have blades (3) which fling off the damping medium. The damping medium is fed to the webs (2) through spraying nozzles (5). Provided along the roll axis in the housing (4) are a plurality of spraying nozzles (5) by means of which a veil of liquid of low height and large lateral extent can be produced. This spraying device delivers a spraying jet with droplets of substantially equal, small size and allows precise metering even of very small quantities of the flung-off damping medium. <IMAGE>

Description

(54) DAMPENING LIQUID SPRAYING DEVICE (71) We, MASCHINENFABRIK AU GSBURG-NijRNBERG AKTIENGESELLSCHAFT, a German company, of 8900 Augsburg, Stadtbachstrasse 1, Germany, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be perfomed, to be particularly described in and by the following state ment: - This invention relates to a dampening liquid spraying device for use with a machine for making or processing paper, particularly although not exclusively a rotary offset printing machine, having centrifuging roller rotatably mounted in a housing which is substantially closed apart from an exit slot.

An object of the invention is to provide such a dampening liquid spraying device which is simply constructed, which produces a spray jet with droplets of predominantly the same small size and which enables even very small quantities of the centrifuged dampening fluid to be dosed accurately.

According to the present invention, there is provided a dampening liquid spraying device for use with a machine for making or processing paper, for example a rotary offset printing machine, comprising a centrifugal roller mounted for rotation in a housing which is substantially closed apart from an exit slot, the centrifugal roller having flanges the radially outer edges of which are sharp and extend generally circumferentially of the roller but are inclined to planes perpendicular to the roller axis, from which edges, in use, dampening liquid is centrifugally flung off in spray form, means being provided for conveying dampening liquid in drop form to the flanges.

A spraying device according to the invention is inexpensive to produce and, in operation it can supply spray jet over the whole machine width, whose quantity of liquid conveyed is constant per unit time and whose droplets size varies only within small limits since an even film of dampening liquid is produced on the flanges by the centrifugal force and the droplets are centrifuged off the sharp edges of the flanges.

Furthermore, the quantity of dampening liquid sprayed by the spraying device is adjustable very precisely as it only amounts to a fraction of the quantity conveyed to the centrifugal roller.

The flanges may be composed of several rings disposed side-by-side, whose planes run obliquely to planes perpendicular to the roller axis, or alternatively, the flanges may be formed by a helical screw-thread form provided on the roller; in this case the flanges may be manufactured by cutting a single start or multi-start screw-thread into the surface of the centrifugal roller.

The means for conveying dampening liquid to the flanges may comprise several spray nozzles disposed side-by-side along the roller axis in the housing and directed towards the centrifugal roller. This makes it possible to dose relatively accurately the quantity of liquid applied per unit of time and per unit of roller surface on to the roller.

Alternatively, the means for conveying dampening liquid to the flanges may comprise several radial projections disposed on the roller between the flanges, the projections extending radially outwardly beyond the sharp edges of the flanges for dipping into dampening liquid located below the centrifugal roller in the housing, means being provided for determining, in use, the level of dampening liquid in the housing so that the level is spaced from the axis of the roller at a distance greater than the radius of the sharp edges of the flanges but smaller than the distance of the outer ends of the projections from the roller axis. This arrangement is characterised by a very simple construction.

The invention may be carried into practice in a number of ways but two specific embodiments will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a cross-sectional view through a spraying device constituting a first embodiment of the invention, Figure 2 is an elevational view of part of the centrifugal roller of the device shown in Figure 1, Figure 3 is a further cross-sectional view, at one end of the spraying device shown in Figure 1, Figure 4 is a cross-sectional view of another spraying device constituting a second embodiment of the invention, and Figure 5 is an elevational view of part of the centrifugal roller of the device shown in Figure 4.

The dampening liquid spraying device illustrated in Figures 1 to 3 has a centrifugal roller 1 mounted for rotation about an axis A-A and driveable by means of a motor (not shown). The rotational speed of the centrifugal roller 1 is expediently variable. The centrifugal roller 1, when the device is mounted for use, extends over the whole width of, for example, a printing machine for printing a paper web, and is mounted at both ends in a manner known per se which is not represented in detail. Cut into the surface of the casing of the centrifugal roller 1, which is expediently made of plastics, is a single start screw-thread forming a plurality of peripheral ridges or flanges 2 which embrace the centrifugal roller in a helically inclined manner and are circumferentially continuous with one another. The flanges 2 each have a wedge shaped profile and terminate in the radially outward direction in sharp edges 3. Instead of forming the flanges 2 by a single start screw-thread, a multiple start screw-thread may of course alternatively be provided. The flanges 2 with the sharp edges 3 extend at an inclination to a plane B-B perpendicular to the roller axis A-A which inclination is equal to the helix angle of the screw-thread.

The centrifugal roller 1 is disposed completely within a housing 4. Also provided in the housing 4, arranged side-by-side at regular spacing are a plurality of spray nozzles directed towards the centrifugal roller 1, which nozzles are expediently designed as flat jet nozzles for issuing, in use, a mist of fluid of relatively small height (i.e. as measured perpendicular to the roller axis) but relatively large lateral range, the flat jet nozzles being arranged so that the relatively large lateral range of the spray jets run parallel to the axis A-A of the centrifugal roller 1. The dampening liquid is conveyed to the spray nozzles 5 by a pump (not shown) via a line 6 which incorporates at least one throttle valve 7 for adjusting the amount of dampening liquid to be applied on to the centrifugal roller 1.

The housing 4 further has an exit slot 8 extending substantially over the entire width of the housing 4. In use, the device is arranged so that in front of this exit slot there will be the roller of the printing machine, not shown, which is to be provided with dampening liquid. The exit slot 8 is bounded at its lower edge, as viewed in Figure 1, by a cover plate 9, constructed in one piece with at least one angled carrier arm 10 partly surrounding the centrifugal roller 1. The free end of the carrier arm 10 is mounted pivotally about an axis 11 fixed relative to the housing. The position of the carrier arm 10 and thus of the cover plate 9 is adjustable by means of an adjustment screw 12 which penetrates the rear wall of the housing 4 and bears against the carrier arm 10. The carrier arm 10 may be held in a form or force-locking manner, for instance by a spring or a pin and slot arrangement in abutment against the end of the adjustment screw 12. By manipulation of the adjustment screw 12, the carrier arm 10 is swivelled about the axis 11. This causes the front edge 13 of the cover plate 9 to be moved in or against the direction of arrow a in order to enlarge or reduce the depth of the opening i.e. as measured perpendicular to the axis A-A, of the exit slot 8.

The upper boundary of the exit slot 8 is formed by a boundary plate 14 which, together with an angled holding plate 15, forms a collecting channel for dampening liquid. The holding plate 15 is attached in an adjustable manner to the front wall of the housing 4 for displacement in or against the direction of arrow b by means of screws (not shown in detail) which penetrate suitable slots. As Figure 3 shows, the exit slot 8 at each end of the housing 4 is covered by means of a shield 16, so that in this region no dampening liquid is able to escape through the exit slot 8. In this region there are openings 17 in the boundary plate 14, through which dampening liquid can run down out of the collecting channel without this dampening liquid affecting the spray jet emerging through the exit slot 8.

The boundary plate 14 is inclined nearer to the horizontal, by an angle a of from 1 to 10 degrees to the upper boundary line 18 of the wedge-shaped spray of liquid passing through the exit slot 8. This boundary line 18 of the droplets issuing through the exit slot 8 in the housing begins at the detachment zone of the liquid from the centrifugal roller 1 and is tangential to the roller 1. The boundary plate 14 has an edge 19 which tapers like a knife towards the centrifugal roller 1. The edge 13 of the cover plate 9 is also similarly tapered. The edges 19 and 13 therefore sever the droplets arriving respectively above the boundary line 18 and those below a lower boundary line 20 of the wedge-shaped spray of liquid droplets issuing through the exit slot 8 in the housing, which lower boundary line 20 begins at the detachment zone of the liquid from the centrifugal roller 1 and is tangential to the centrifugal roller 1, and ensure that these droplets flow back in to the bottom of the housing 4 either directly along the cover plate 9 or via the collecting channel formed by the plates 14, 15 and the openings 17.

The position and shape of the boundary plate 14 prevents droplets, centrifuged above the boundary line 18, from being able to fall from the upper boundary of the exit slot 8 through the spray jet which would otherwise alter the size of the droplets of this jet or uncontrollably increase the amount of dampening liquid impinging on the printing machine roller. Connected to the base of the housing 4 is a discharge line 21 for the dampening liquid, so that the dampening liquid will not collect in the housing 4 and its level can therefore never rise as far as the centrifugal roller 1.

When the spraying device is in operation.

the centrifugal roller 1 is rotated in the direction of the arrow c. At the same time dampening liquid is sprayed onto the centrifugal roller 1 in droplet form by means of the spray nozzles 5. The spray jet of each spray nozzle 5 is defined by boundary lines 22, 23. The arrangement is so made that the boundary line 23 is staggered by a sector of angle of about 150 degrees relative to the beginning of the detachment zone, determined by the beginning of the boundary line 18, of the droplets leaving the surface of the centrifugal roller 1. Along the sector of the centrifugal roller 1 determined by the angle the droplets applied by means of the spray nozzles 5 are dispersed largely uniformly over the sides of the flanges 2 forming a fine liquid layer. To achieve adequate uniformity of the liquid layer on the flanges 2, the angle 13 should be at least 90 degrees. It is unimportant here that just after the boundary line 23 in the direction of rotation of the roller 1 droplets are already being centrifugally flung from the centrifugal roller 1 because these droplets are collected by the housing 4. Within the detachment zone determined by the boundary lines 18 and 20, however, small droplets which are largely consistent in their size detach themselves from the sharp edges 3 of the flanges 2 of the centrifugal roller 1. Since the position of the sharp edges 3 centrifuging droplets through the exit slot 8 continuously varies relative to the exit slot 8 in the direction of the axis A-A owing to the fact that the flanges 2 are formed by a screw-thread, also in this longitudinal direction a very uniform release of small droplets is produced.

Since only a fraction of the dampening liquid applied by the spray nozzles 5 leaves the housing 4 through the exit slot 8, very precise control of the quantity of the dampening liquid sprayed on to the dampening device roller can be achieved by varying the quantity of liquid sprayed through the nozzles 5 by the throttle valve or valves 7. There is, moreover the further possibility of varying the quantity of dampening liquid sprayed by the means already described for adjusting the positions of the cover plate 9 and of the boundary plate 14. Different quantities of dampening liquid can be discharged in different axial sections either by the arrangement of several throttle valves 7 for adjacent nozzles 5 and/or by a cover plate 9 or boundary plate 14 divided several times over the width of the housing 4.

In the embodiment shown in Figures 4 and 5, there is again provided a centrifugal roller, designated 25. extending over the whole width of the printing machine and rotatably mounted at each end. The centrifugal roller 25 comprises a roller base body 26 on which is mounted a series of rings 27 made of plastics material. Each ring bears a flange 28 extending in a radially outward direction which terminates in a sharp edge 29. The rings 27 are mounted on the roller base body 26 in such a manner that their planes run obliquely to a plane D-D perpendicular to the axis C-C of the centrifugal roller 25. With rings 27 which are manufactured from a deformable plastics material, this oblique position may be achieved in a simple manner by screwing wedge-shaped end pieces 30 on to the ends of the roller base body 26 which force the rings by the required amount out of the planes perpendicular to the roller longitudinal axis C-C. The flanges 28 again have an approximately wedge-shaped profile which is rounded off at the junction with the adjacent flange.

The centrifugal roller 25, moreover. bears radial projections 31 which protrude radially outwardly beyond the sharp edges 29 and which are mutually spaced both axially (see Figure 5) and in the circumferential direction (see Figure 4) of the periphery of the centrifugal roller 25. The projections 31 are designed as short metal lamellae and are each provided with an angled foot 32 which is pushed below an adjacent ring 27 to secure the radial projection 31 in position.

Expediently. the leading edge 33 of each projection 31 in the direction of rotation of the roller 25 denoted by the arrow d is tapered in the shape of a cutting edge.

The centrifugal roller 25 is again disposed in the interior of a housing 34 which has an exit slot 35. Just as in the first embodiment, the size of the exit slot 35 is adjustable, on the one hand, by means of a cover plate 36 and on the other hand, by means of a boundary plate 37. Into the lower part of the housing 34 opens a dampening liquid supply line 38, and there is a discharge slot 39 provided in the rear wall of the housing 34, behind which is disposed a discharge channel 41, connected to a dampening liquid discharge line 40, which has an overflow lip 42 extending parallel to the discharge slot 39.

The discharge channel 41 and with it the overflow lip 42 may be displaced in or against the direction of arrow e relative to the housing 34 by means of screws 43 which penetrate slots 44. By this means, the surface 45 of the dampening liquid 46 located in the lower part of the housing 34 may be arranged to be raised or lowered.

The surface 45 is adjusted relative to the centrifugal roller 25 such that the projections 31 dip into the surface of the liquid but the cutting edges 29 do not touch this surface.

When the spraying device is in operation, the centrifugal roller 25 is rotated in the direction of arrow d. In the course of this the projections 31 each strike the surface 45 successively and then move a short distance through the dampening liquid 46. Drops of the liquid are thrown upwards here which wet the flanges 28. The arrangement is designed such that the upper boundary line 47 of the wedge-shaped spray passing through the exit slot 35, which line is again a tangent to the centrifugal roller 25 beginning at the detachment zone of the droplets from the roller 25, is staggered by an angle of y = 215 degrees relative to the point of impact 49 of a projection 31 on to the surface 45 of the dampening liquid 46. In this arrangement, too, the droplets impinging on to the flanges 28 are again dispersed along the sector of the centrifugal roller 25 determined by the angle y largely uniformly over the sides of these flanges forming a thin layer of liquid. It was found that in order to obtain an adequate uniformity of this layer of liquid, the angle y should be at least 90 degrees; that angle ensures that the small droplets detaching themselves within the upper and lower boundary lines 47 and 48 from the edges 29 of the flanges 28 are largely consistent in their size. Since in this form of construction too, the position of the sharp edges 29 centrifuging the droplets continuously varies relative to the exit slot 35 in the direction of the axis C-C, a very uniform discharge of droplets in the longitudinal direction is obtained here as well.

As well as the possibility of influencing the amount of dampening liquid sprayed by adjusting the positions of the cover plate 36 and of the boundary plate 37, the amount of liquid can also be influenced in this form of construction by adjusting the level of the liquid surface 45 by raising or lowering the discharge channel 41.

The invention is not restricted to the embodiments represented. Thus, for instance, the exit slot may also be provided in the top wall of the housing so that the spraying device can be accommodated in a space saving manner below the rollers and cylinders of an offset printing machine which are to be provided with dampening liquid.

A spraying device according to the invention can be used not only for applying dampening liquid to the printing plate in offset printing machines, but it may also be used to moisten the paper before printing or after the drier of a printing machine. Use with paper manufacturing machines is also possible.

WHAT WE CLAIM IS: 1. A dampening liquid spraying device for use with a machine for making or processing paper, for example a rotary offset printing machine, comprising a centrifugal roller mounted for rotation in a housing which is substantially closed apart from an exit slot, the centrifugal roller having flanges the radially outer edges of which are sharp and extend generally circumferentially of the roller but are inclined to planes perpendicular to the roller axis, from which edges, in use, dampening liquid is centrifugally flung off in spray form, means being provided for conveying dampening liquid in drop form to the flanges.

2. A spraying device as claimed in claim 1 in which the flanges are composed of a plurality of rings disposed side-by-side, whose planes run obliquely to planes perpendicular to the roller axis.

3. A spraying device as claimed in claim 1, in which the flanges are formed by a helical screw-thread provided on the roller.

4. A spraying device as claimed in claim 3, in which the helical screw-thread is a multiple start screw-thread.

5. A spraying device as claimed in any one of the preceding claims, in which the flanges have an approximately wedgeshaped profile.

6. A spraying device as claimed in any one of the preceding claims, in which the means for conveying dampening liquid to the flanges comprises a plurality of spray nozzles disposed side-by-side in the housing along the roller axis and directed towards the centrifugal roller.

7. A spraying device as claimed in claim 6, in which the spray nozzles are designed as flat jet nozzles discharging a mist of liquid of relatively small height, as measured perpendicular to the roller axis and relatively large lateral range parallel to the roller axis.

8. A spraying device as claimed in claim

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. the one hand, by means of a cover plate 36 and on the other hand, by means of a boundary plate 37. Into the lower part of the housing 34 opens a dampening liquid supply line 38, and there is a discharge slot 39 provided in the rear wall of the housing 34, behind which is disposed a discharge channel 41, connected to a dampening liquid discharge line 40, which has an overflow lip 42 extending parallel to the discharge slot 39. The discharge channel 41 and with it the overflow lip 42 may be displaced in or against the direction of arrow e relative to the housing 34 by means of screws 43 which penetrate slots 44. By this means, the surface 45 of the dampening liquid 46 located in the lower part of the housing 34 may be arranged to be raised or lowered. The surface 45 is adjusted relative to the centrifugal roller 25 such that the projections 31 dip into the surface of the liquid but the cutting edges 29 do not touch this surface. When the spraying device is in operation, the centrifugal roller 25 is rotated in the direction of arrow d. In the course of this the projections 31 each strike the surface 45 successively and then move a short distance through the dampening liquid 46. Drops of the liquid are thrown upwards here which wet the flanges 28. The arrangement is designed such that the upper boundary line 47 of the wedge-shaped spray passing through the exit slot 35, which line is again a tangent to the centrifugal roller 25 beginning at the detachment zone of the droplets from the roller 25, is staggered by an angle of y = 215 degrees relative to the point of impact 49 of a projection 31 on to the surface 45 of the dampening liquid 46. In this arrangement, too, the droplets impinging on to the flanges 28 are again dispersed along the sector of the centrifugal roller 25 determined by the angle y largely uniformly over the sides of these flanges forming a thin layer of liquid. It was found that in order to obtain an adequate uniformity of this layer of liquid, the angle y should be at least 90 degrees; that angle ensures that the small droplets detaching themselves within the upper and lower boundary lines 47 and 48 from the edges 29 of the flanges 28 are largely consistent in their size. Since in this form of construction too, the position of the sharp edges 29 centrifuging the droplets continuously varies relative to the exit slot 35 in the direction of the axis C-C, a very uniform discharge of droplets in the longitudinal direction is obtained here as well. As well as the possibility of influencing the amount of dampening liquid sprayed by adjusting the positions of the cover plate 36 and of the boundary plate 37, the amount of liquid can also be influenced in this form of construction by adjusting the level of the liquid surface 45 by raising or lowering the discharge channel 41. The invention is not restricted to the embodiments represented. Thus, for instance, the exit slot may also be provided in the top wall of the housing so that the spraying device can be accommodated in a space saving manner below the rollers and cylinders of an offset printing machine which are to be provided with dampening liquid. A spraying device according to the invention can be used not only for applying dampening liquid to the printing plate in offset printing machines, but it may also be used to moisten the paper before printing or after the drier of a printing machine. Use with paper manufacturing machines is also possible. WHAT WE CLAIM IS:

1. A dampening liquid spraying device for use with a machine for making or processing paper, for example a rotary offset printing machine, comprising a centrifugal roller mounted for rotation in a housing which is substantially closed apart from an exit slot, the centrifugal roller having flanges the radially outer edges of which are sharp and extend generally circumferentially of the roller but are inclined to planes perpendicular to the roller axis, from which edges, in use, dampening liquid is centrifugally flung off in spray form, means being provided for conveying dampening liquid in drop form to the flanges.

8. A spraying device as claimed in claim

6 or claim 7, in which the zone of impact of the spray jets of the nozzles is angularly offset by an angle of at least 90 degrees ahead, relative to the direction of rotation of the roller, of the detachment zone of the droplets centrifuged out through the exit slot in the housing.

9. A spraying device as claimed in any one of claims 1 to 5, in which the means for conveying dampening liquid to the flanges comprises a plurality of radial projections disposed on the roller between the flanges, the projections extending radially outwardly beyond the sharp edges of the flanges for dipping into dampening liquid located below the centrifugal roller in the housing, means being provided for determining, in use, the level of dampening liquid in the housing so that the level is spaced from the axis of the roller at a distance greater than the radius of the sharp edges of the flanges but smaller than the distance of the outer ends of the projections from the roller axis.

10. A spraying device as claimed in claim 9, in which the projections are mutually spaced axially and circumferentially over the periphery of the centrifugal roller.

11. A spraying device as claimed in claim 9 or claim 10, in which the projections are designed as flat lamellae which are each disposed in a respective plane perpendicular to the roller axis.

12. A spraying device as claimed in claim 11, in which the leading edge of each projection relative to the intended direction of rotation of the roller is tapered in the form of a cutting edge.

13. A spraying device as claimed in any one of claims 9 to 12, in which the housing is adapted so that the level of dampening liquid in the housing is variable by means of an adjustable overflow lip.

14. A spraying device as claimed in any one of claims 9 to 13, in which the means for determining the level of the dampening liquid in the housing and the exit slot in the housing are arranged such that, in use, the immersion point of each projection into the liquid surface is angularly offset by an angle of at least 90 degrees ahead, relative to the direction of rotation of the roller, of the detachment zone of the droplets centrifuged out through the exit slot in the housing.

15. A spraying device as claimed in any one of the preceding claims, in which to dose the quantity of the dampening liquid the depth of the exit slot, i.e. the dimension in a plane perpendicular to the roller axis, is adjustable.

16. A spraying device as claimed in claim 15, in which the boundary of the exit slot at the trailing edge thereof, relative to the direction of rotation of the roller, is formed by at least one positionally adjustable cover plate.

17. A spraying device as claimed in claim 16, in which the cover plate is carried by an angled carrier arm mounted pivotally about an axis fixed relative to the housing, the position of the carrier arm being adjustable by means of an adjustment screw.

18. A spraying device as claimed in any one of the preceding claims, in which the housing is adapted to be mounted such that the exit slot is in a side wall of the housing.

19. A spraying device as claimed in claim 18, in which the boundary of the exit slot at the leading edge thereof, relative to the direction of rotation of the roller, is afforded by a boundary plate which is the intended position of mounting the housing rises towards the interior of the housing, and which, together with an angled holding plate attached adjustably to the front wall of the housing, forms a collecting channel for dampening liquid, in which at the ends of the collecting channel openings are provided for the return of dampening liquid.

20. A spraying device as claimed in claim 19, in which in the intended mounting position of the housing the boundary plate is inclined nearer to the horizontal by an angle of from 1 to 10 degrees to a tangent to the centrifuging roller at the beginning of the detachment zone of the droplets issuing through the exit slot in the housing.

21. A spraying device as claimed in claim 19 or claim 20, in which the edge of the boundary plate facing the centrifuging roller is tapered.

22. A dampening liquid spraying device substantially as specifically described herein with reference to Figures 1 to 3 or to Figures 4 and 5 of the accompanying drawings.

23. A spraying device as claimed in any one of the preceding claims when arranged adjacent a roller or cylinder of a paper making or processing machine, the housing being mounted so that the axis of the centrifuging roller is parallel to the machine roller or cylinder and the housing exit slot opens towards the latter.

24. A paper making or processing machine including a spraying device as claimed in any one of claims 1 to 22.