GB2602242A

GB2602242A - A seal assembly for chambered doctor blade apparatus

Info

Publication number: GB2602242A
Application number: GB2011594.5A
Authority: GB
Inventors: Gordon Paul
Original assignee: Individual
Current assignee: Individual
Priority date: 2020-07-27
Filing date: 2020-07-27
Publication date: 2022-06-29
Anticipated expiration: 2040-07-27
Also published as: GB202011594D0; GB2602242B

Abstract

A modular seal assembly 100 comprises a cartridge unit 102 having a pair of separate end wall members 102A, 102B between which is disposed an intervening rigid seal support member 102D, 102E. All said members have the same cross-sectional shape and are connected together in aligned fashion, except that the intervening member is smaller so that a recess is defined between the end wall members and above the intervening support member when the cartridge unit is assembled. Within this recess, at least one resiliently compressible seal rib 102F, 102G is provided, which is thus supported from underneath by that surface of the intervening support member lying adjacent the underside of the seal rib. The depth of the seal rib is such that when fully disposed in the recess, some portion thereof stands proud above the end wall members lying on either side thereof. The cartridge unit further comprises at least two axial springs 102J, 102K disposed between each of the two end wall members and the intervening support member for resiliently biasing the end wall members away from the intervening support member. The cartridge unit further comprises engagement means 102A-1, 102B-1, 102C-1 to support the seal rib.

Description

A Seal Assembly for Chambered Doctor Blade Apparatus

Field of the Invention

The present invention relates to a seal assembly for chambered doctor blade apparatus, and specifically an end seal assembly for said apparatus, one of each of said assemblies being commonly provided proximate the remote free ends of the apparatus. Yet further specifically, the present invention relates to a modular floating end seal assembly for chambered doctor blade apparatus which includes a chamber body, one such assembly being provided at each end thereof and which, together with the doctor blades and their free edges, and the adjacent arcuate surface of a printing or coating cylinder with which the doctor blade edges and the seals come into contact when the chambered doctor blade apparatus is operatively disposed adjacent and against the said cylinder, define a sealed chamber such that, when said chamber is filled with a printing or a coating liquid, commonly under slight pressure, the liquid is not only sealingly contained within said chamber but also urged against the arcuate surface of the printing or coating cylinder in a generally uniform and consistent manner along its entire length.

Background to the Invention

Chambered doctor blade systems and apparatus are well known in the printing and coating industries, and such systems and apparatus are currently in widespread use, particularly for more demanding, high-resolution, and/or high-accuracy printing and coating applications, as it is widely believed that chambered (also known as "metered") doctor blade systems are capable of applying a uniform layer of liquid over that arcuate portion of the surface of an Anilox cylinder against which the chambered doctor blade apparatus is disposed in a more consistent, repeatable and finely adjustable fashion than other liquid application systems, such as ink fountains and their corresponding fountain rollers, or rubber doctor rollers. Although modern chambered doctor blade systems can be complex, in essence and in functionality they are relatively simple.

For example, in Figure 1 (prior art), there is shown the fundamental components of a chambered doctor blade liquid application and printing system, referenced generally at 2. In particular, a liquid supply and associated pumping apparatus 4 is connected, generally in closed fashion, to both liquid delivery and return pipework 6, 8 respectively whereby the liquid, which may be any printing ink or coating liquid (e.g. a varnish or a lacquer), is pumped into a chamber 10 defined within and at least partially by a chambered doctor blade unit indicated generally at 12, through inlet and outlet ports 14, 16 respectively provided on a rear surface 18 of unit 12. As can be seen in the Figure, the unit 12 is disposed adjacent a cylindrical Anilox roll 30, and the chamber 10 is completed and closed by that arcuate portion of roll 30 defined between the free edges of a pair of doctor blades 20, 22 clamped in oppositely inclined fashion to the unit 12, the contact of one (20) of which with the Anilox roll surface can be seen in the enlarged portion of the Figure. In most chambered doctor blade systems, the thickness, shape, profile, and rigidity of the doctor blades, particularly as regards their tips and the doctor blade surfaces immediately proximate, are different for each doctor blade, 20, 22. This is because the function of each of the blades is somewhat different, depending fundamentally on the disposition of unit 12 relative to roll 30, and of course the direction of rotation of said roll. In the embodiment shown in the Figure, Anilox roll 30 rotates anticlockwise, and thus doctor blade 20 functions as a containment doctor blade, whereas doctor blade 22 is known commonly as a metering doctor blade. The first type ("containment") serves firstly to "contain" the printing ink or other fluid within the chamber 10, and secondly to allow any ink or fluid residue remaining on the Anilox roll to pass beneath it and back into the chamber, and therefore containement doctor blades are commonly somewhat thinner and more flexible than their metering counterparts. By contrast, the metering doctor blade 22 is often substantially thicker and more rigid, and the design of the tip thereof may be quite different to that of the containment blade, because it is the metering doctor blade which ultimately determines the thickness and uniformity of the layer of ink or printing fluid which remains on the Anilox roll after the cylindrical surface thereof scrapes past the metering doctor blade, from a position where it is within the chamber 10 behind blade 22, into a position where it is open to the atmosphere beyond said blade.

The remaining aspects of the printing apparatus depicted in the Figure are well known, but for completeness, continued rotation of the Anilox roll 30 ultimately brings the arcuate portion thereof which has been precisely coated into contact with a plate cylinder 40 to the exterior surface of which is mounted a relief patterned printing plate (not shown) requiring a coating of ink or other fluid. Upon contact, the ink or other fluid is transferred from the surface of the Anilox roll 30 to the desired (raised, relief) portions of the printing plate mounted on the plate cylinder, which itself rotates so that the ink-coated plate comes into contact with a continuously moving web of a substrate material 50 which is thus printed as the ink is transferred from the plate cylinder thereto. As is common practice, the substrate is nipped between the plate cylinder and an impression cylinder 60 to improve the effectiveness of the ink transfer between plate cylinder and substrate, and thus the effectiveness of the print (or coating).

As will be appreciated by persons skilled in the art, Figure 1 provides a purely schematic end elevational view, and in practice, the chambered doctor blade unit 12 is an elongate component having a length broadly equal to the axial length of the adjacently disposed Anilox cylinder 30, the length of which, as well as the length of the plate and impression cylinders, is ultimately determined by the width of the substrate 50, or at least the width of that portion thereof which is to be printed.

Furthermore, although of course not illustrated in Figure 1, the skilled reader will understand that chamber 10 is closed at either end, and as is common for all chambered doctor blade systems, a pair of appropriately shaped end seals will be provided, each being usually directly secured to the body of unit 12 behind and to the inside of an end retaining wall thereof such that each end seal is disposed immediately underneath end regions of each of the blades which are thus partially supported thereby.

For example, referring briefly to Figures 2, 2A, in which a perspective view of one end of a chambered doctor blade unit and an end seal are respectively schematically illustrated, the relative arrangement of blades 20, 22 and a conventional end seal 24 can be seen. In particular, end seal 24 (see also Figure 2A) is suitably shaped and sized according to the cross-sectional shape of the chamber 10 and is provided with a profiled upper edge divided into three distinct surface portions, 24A, 24B, 24C. Surface portions 24A, 24C are substantially planar and upwardly inclined relative to a base 24D of the end seal such when in position within the unit 12, said surfaces are disposed immediately underneath end regions of blades 20, 22 and thus provide some resilient support therefor. Surface 248 of the end seal 24 is curved and extends between surfaces 24A, 24B substantially centrally of the end seal as a whole, and in most circumstances, the radius of curvature of surface 24B is substantially similar if not identical to the radius of curvature of the Anilox roll 30 with which it comes into contact when the chambered doctor blade unit 12 is moved into its operating position as shown in Figure 1. As the skilled person will understand, when unit 12 is in this position, the chamber 10 is completely closed and sealed from the ambient atmosphere because: (1) the end seals 24 define end walls of chamber 10 which are sealed against whatever portion of the cylindrical surface of the Anilox roll 30 they are in contact with at any particular time, and (2) the edges of blades 20,22 interface with corresponding elongate narrow areas of the Anilox roll in sealing fashion, as a result of either their being in contact with the surface of Anilox roll 30 along substantially its entire length, or disposed so closely thereto that, together with whatever printing or coating liquid is present in the chamber 10 and on the surface of the Anilox roll 30 during operation, a sealing function is effectively achieved.

Aside from such seals, the chamber 10 is further defined by chamber cavity side walls and a base (not referenced) provided in the unit itself and of course whatever arcuate portion of the Anilox roll is any particular time disposed between the blade edge/Anilox roll interface regions.

Heretofore, end seals have been essentially simple, inexpensive components commonly constituted solely of an open-or closed-cell polymer foam material having sufficient resiliency and compressibility so that the end seal can both provide spring-like support for the end regions of the blades which slightly compress the end seals when clamped in place on either side of the chambered doctor blade unit, and also create a good seal with the respective surface of the Anilox roll with which it comes into contact. In particular, one reason that foam or foam-like materials are chosen is that the elastic response of such materials is largely non-linear, and in particular they can be significantly elastically deformed, in particular in compression, without corresponding significant increases in the force required to achieve such deformation. This property is well known in foams, and means that an end seal made of such foam material can effectively be compressed against and conform to the curved surface of the Anilox roll, even if the radius of curvature of the latter is not exactly identical to that of the curved surface of the end seal, and provided the degree of compression of the end seal is significant enough (beyond the minimal initial linear response of the foam), the contact pressure between the end seal and Anilox roll does not vary too significantly over the entire area of contact, and thus the effectiveness of the seal provided by that contact is similarly reasonably uniform. Thus small differences between the Anilox surface radius of curvature and that of the curved surface of the end seal can quite easily be accommodated, and indeed in practice and in production environments often are.

There are various known fundamental problems with conventional end seals, the most prevalent of which their propensity to leak. As will be readily understood, end seals will generally always leak once they become sufficiently worn, torn or otherwise damaged, but end seal leakage issues are also certainly experienced in production environments without any significant wear or other damage to the end seal. Indeed, the end seals are often regarded as the weakest link in (usually) pressurised chambered doctor blade systems. Although leakages through end seals of often chemically aggressive printing or coating liquids can be messy and in some cases (if the liquid spurts) dangerous, the more pervasive problem is the compromise in liquid pressure within the chamber and the concomitant compromise in the uniformity of liquid application to the Anilox roll, particularly in regions thereof proximate the end seal, resulting in unsatisfactory printing results.

Various improvements and modifications to end seals and have already been proposed in an attempt to overcome or at least mitigate leakage issues. For example, GB2315460, on the face of it at least, would appear to disclose a spring-mounted floating seal assembly in which is provided a pair of spaced-apart profiled rib-like seal pieces which together act (in conjunction with the surface of the Anilox roll) to provide not only a double and thus automatically more secure seal, but also a closed intervening initially air-filled channel between respective seal pieces which may completely eliminate the possibility of pressurised printing liquid spurting uncontrollably from within the chamber to the ambient atmosphere beyond the seal.

The concept of utilising a spaced-apart pair of conventionally shaped end seals in a single seal assembly adapted to be used at one or other end of an ink or other printing fluid chamber is disclosed in US2016/0147180. In particular, in Figs. SB, SC a seal body is shown provided with two spaced-apart slots into each of which a seal shown in Fig.5A is received and fully inserted, before the seal body with seals in-situ therein is then secured within and at one or other end of a chamber before subsequently being brought into contact with an Anilox roll.

Although the abovementioned prior art seal configuration and assemblies do at least mitigate against some of the problems of experienced by chambered doctor blade systems employing only very basic end seals, leakage issues do nevertheless continue to persist, and it is a primary object of this invention therefore to provide a yet further improved seal assembly which not only substantially eliminates the leakage of liquids between the Anilox roll and the one or more seals within the assembly, but which further improves the lateral resistance of the one or more seals within the assembly to outward deflection as a result of static or dynamic pressures exerted on the seal side wall(s) by the liquid within the chamber of the chambered doctor blade apparatus.

A further disadvantage of most if not all known end seals and the assemblies in which they may be disposed arises from the fact that when the seals are in their operative position, their uppermost surfaces are not only in contact with the curved surface of the Anilox roll, but to ensure a good seal therewith as achieved, the seal as a whole is compressed against the Anilox roll. Although a lubricating composition is commonly applied to or impregnated in the upper contact surface (at least) of the seal, the fact that the seal is compressed against the curved surface of the rotating Anilox roll (which, in some high speed applications, may rotate many hundreds or even 1000s of times per minute) inevitably gives rise to non-negligible frictional forces over the contact surface of the seal. These forces will of course only act in one direction along the contact surface of the seal as the Anilox roll rotates, and will therefore give rise to a torque about the centroid of the seal body which tends to cause one end of the seal (the end most proximate where the Anilox roll surface first comes into contact with the seal contact surface) to lift vertically upwards and away from its initial mounting position, and simultaneously and equally cause the opposite end of the seal (the end most proximate where the Anilox roll surface rotates off and away from the seal contact surface) to drop below and beneath its initial steady-state mounting position. Naturally, the frictional forces, and thus the torque generated on the seal, will increase with the speed of rotation of the Anilox roll, and therefore the tendency of the seal as a whole to rotate in this manner will also increase, with the result that leaks become more likely as the trailing end (with regard to the direction of rotation of the Anilox roll) of the contact surface of the seal moves away from the surface of the Anilox roll. This problem is exacerbated by the fact that the material of the seal itself is inherently and relatively easily compressible In most conventional seal mounting arrangements, the only resistance to the torque experienced by the seal when in use is provided by the reaction of the base of the seal, or possibly in some prior art arrangements, the side edges of the seal, against the body or assembly in which it is inserted or mounted. In some embodiments, seals are commonly connected to the chamber bodies by bolts or the like which pass through apertures provided axially through the seal bodies proximate their lowermost or base edges, i.e. the edge most remote from the operative, sealing contact surface of the seal, and such bolts may thus provide some degree of resistance to the tendency of the seal body to rotate as a result of torque exerted on the seal body as a result of friction. However, in all cases, the only resistance to the frictionally generated torque in the vicinity of the contact surface is provided by the material of seal itself, which being inherently compressible, provides very little resistance at all.

In view of the above, it is a further object of the present invention to provide a seal assembly, modular or otherwise, which significantly improves resistance of the seal, particularly in the vicinity of the contact surface thereof which comes into contact with the Anilox roll, to frictionally generated torques which tend to rotate the seal away from its steady-state mounting position and which thus inevitably reduce the contact pressure at the trailing edge of the contact surface (as regards the rotational direction of the Anilox roll) of the seal rendering it much more vulnerable to leaks.

It is a yet further object of the present invention to provide a modular seal assembly which can not only be easily removed, dismantled and reassembled for cleaning and maintenance purposes, but which can also be very readily, quickly and easily adjusted and modified to allow a variety of different seals of different sizes, shapes, and edge surface profiles to be mounted within the assembly.

It is a yet further object of the present invention to provide a modular seal assembly which allows for quick and easy removal of one or more of the seals within it, and in some preferred embodiments, without first requiring complete disassembly or needing to be completely disconnected and removed from the chambered doctor blade apparatus of which, in use, it forms part.

Summary of the Invention

According to a first aspect of the present invention, a modular seal assembly comprising or consisting of at least one cartridge unit which constituted of at least a pair of rigid separate end wall members and at least one intervening rigid seal support member disposed between said end wall members, all of said members being of the same general cross-sectional shape and being connected together in substantially aligned fashion by means of one or more bolts extending through the cartridge unit from one end wall member to the other and passing through the intervening member thus fixing the disposition thereof relative to the adjacent end wall members, said cross-sectional shape having an upper portion which includes at least one arcuately concave edge region, and a base portion which is essentially straight such that over the upper portion, in the axial thickness direction of each member, there is defined a correspondingly arcuately concaved surface, the cross-sectional shape of said intervening member being dimensionally smaller than that of both adjacent end wall members such when assembled, a recess is defined between respective end wall members which extends over at least the arcuately concave surface of the intervening member, said cartridge assembly further comprising at least one resiliently compressible seal rib having a cross-sectional shape substantially corresponding to that of the recess but being of greater depth such that when the seal rib is fully inserted into the recess and comes into contact with the arcuately concaved surface of the intervening seal support member, at least some portion of the seal rib stands proud above the arcuately concaved surfaces of the end wall members lying on either side thereof, Characterised in that The cartridge unit further comprises at least two axial springs, a first axial spring being disposed between an inwardly facing side wall of one end wall member and the respective adjacent side wall of the intervening member, and a second axial spring being disposed between one inwardly facing side wall of the other end wall member and the respective alternate adjacent side wall of the intervening member, such that in a first, open condition wherein the one or more bolts are loosened, the end wall members are biased by said axial springs sufficiently outwardly and away from the intermediate member to release any extant seal rib for removal, and such that, in a second, closed condition wherein the one or more bolts are tightened and the respective side walls of the end wall members and the intermediate member are brought into more proximate relationship, one or more of: at least some portion of the inwardly facing edges of the end wall members, and engagement means, provided on at least one of the inwardly facing side walls of said end wall members and adjacent and proximate at least some portion of their inwardly facing edges, engages with and axially compresses the seal rib against one or other of: the alternate end wall member, the corresponding inwardly facing edge of the alternate end wall member, or the engagement means provided adjacent and proximate the inwardly facing edge of the alternate end wall member, as the case may be.

Preferably, the cartridge unit comprises two bolts disposed preferably substantially laterally symmetrically on either side of the centroids of the end wall and intervening members, and at least 4 axial springs are provided, two of which are disposed between the inwardly facing side wall of one end wall member and the respective adjacent side wall of the intervening member, and the remaining two being disposed between the inwardly facing side wall of the alternate end wall member and the respective adjacent side wall of the intervening member. Preferably, each of said axial springs is disposed in similarly symmetrical positions relative to the centroids of the respective members, and each of said pair of bolts passes through a corresponding pair of the axial springs disposed in axial alignment on either side of the intervening member. Further preferably, the axial springs are circular in cross-section, and in a yet further preferred arrangement, the inwardly facing side walls of the end wall members are provided with counterbores of a diameter corresponding to that of the axial springs, and of a depth less than that of the length of the axial springs such that said axial springs can be at least partially received, located and/or retained within said counterbores, which are of course preferably co-axial with the apertures provided through said end wall members and the intervening member and through which the shanks of said bolts pass or are at least partially received.

In a yet further preferred arrangement, the cartridge unit further comprises a rigid intermediate central wall member, and a pair of intervening rigid seal support members disposed on either side thereof such that one intervening member is thus disposed between a first end wall member and one side of the intermediate central wall member, and the other intervening member is disposed between the alternate end wall member and the other side of the intermediate central wall member. Again, in this preferred arrangement, all of said members are of the same general cross-sectional shape and are connected together in substantial alignment by means of one or more bolts extending substantially through the cartridge unit from one end wall member to the other and passing through all of the intervening seal support members and the intermediate central wall member, and thus fixing their dispositions relative to one another. Most preferably, the cross-sectional shape of the intermediate central wall member will also include an upper portion which includes at least one arcuately concave edge region, and a base portion which is essentially straight, and dimensionally, the cross-sectional shape of the intermediate wall member is broadly identical to that of the end wall members such that, when assembled, a pair of recesses is defined between the intermediate central wall member and respective end wall members, one on each side of the intermediate central wall member, said recesses extending over at least the arcuately concave surfaces of each of the intervening seal support members provided on either side of the intermediate central wall member. In this arrangement, said cartridge assembly further preferably comprises at two resiliently compressible seal ribs having preferably identical cross-sectional shapes substantially corresponding to that of each of the recesses, but each being of greater depth such that when the seal ribs are fully inserted into the recesses and come into contact with the arcuately concaved surface of the respective intervening members, at least some portion of each seal rib stands proud above the arcuately concaved surfaces of the end wall members and intermediate central wall member lying on either side of the seal ribs.

Preferably, one or more of: one or both of the inwardly facing side walls of the end wall members, and one or both of the side walls of the intermediate central wall member, are provided with engagement means disposed proximate and/or immediately beneath and alongside at least some portion of the arcuately concave edges of said members, such that said engagement means axially engages with and then compresses a side surface of that seal rib disposed immediately adjacent thereto when the bolts are tightened and the various members of the cartridge are brought into axially closer relationship. Further preferably, the engagement means, when provided, are one of: continuous, discontinuous, and discrete. For example, the engagement means may take the form of one or more of: a continuous or discontinuous axially protruding rib, teeth or pin-like formations, either integrally formed with, or otherwise connected to a relevant side wall of the member they are provided on. In the most preferred case, the engagement means take the form of a plurality of discrete pins, and most preferably the engagement means are provided by a plurality of grub screws which are screwed into a corresponding plurality of tapped holes in the inwardly facing side walls of one or (most preferably) both end wall members, and/or the intermediate central wall member.

In the case where the cartridge unit is provided with an intermediate central wall member, then engagement means are preferably provided on both side walls thereof, proximate and/or immediately beneath and alongside at least a portion of the edges of said side walls, in particular the arcuately concave edges thereof. In the particular case of the intermediate central wall member, the engagement means may be provided by grub screws of a length greater than the axial thickness of that central wall member such that they can be screwed into and through tapped holes provided therein, such that a portion of each grub screw stands proud of each side wall on either side of the central wall member. In preferred embodiments, the engagement means provided on the end wall members, and optionally also on the intermediate central wall member Of present) are axially aligned with respect to one another, such that when bolts are tightened, the engagement means on those members on the opposite sides of a seal rib disposed in the recess defined between them not only come into contact with the side walls of that seal rib, but also the engagement means on one wall member provides a reaction surface and thus react against those on the other. In other embodiments, the engagement means provided on adjacent wall members may be disposed in offset relationship. In any event, the engagement means are most preferably provided proximate and/or immediately beneath and alongside one or more of: - the arcuately concave edge regions of the cross-sectional shape of the inwardly facing side wall of any end wall member, - the arcuately concave edge regions of the cross-sectional shape of one or both side walls of any intermediate central wall member, - any other edge region, not being a base edge, of the cross-sectional shape of the inwardly facing side wall of any end wall member, and - any other edge region, not being a base edge, of the cross-sectional shape of one or both of the side walls of any intermediate central wall member.

In most preferred arrangements, the cross-sectional shape of the end-wall members, the intervening seal support members, and any intermediate central wall member of the cartridge unit is substantially symmetrical about a vertical axis passing through the centroid of any such member, said cross-sectional shape comprising a substantially straight base portion from which upwardly perpendicularly vertically extend a pair of side edges of equal length, from which, in turn extend a pair of inclined edges which subtend an obtuse angle with the side edges and are inclined toward one another over the base portion, and finally a substantially centrally, symmetrically disposed arcuately concave edge which extends between the respective ends of inclined edges to complete the cross-sectional shape. In at least some preferred embodiments, engagement means are provided alongside, adjacent and immediately beneath at least some part of both the inclined edges and the arcuately concave edge of one or more of: the inwardly facing side walls of any or both end wall members, one or both side wall surfaces of any intermediate central wall member.

Most preferably, the seal ribs are substantially or entirely constituted of a resiliently compressible foam or foam-like material, which is preferably chemically inert, and most preferably also inherently phobic or repellent to the most common printing and coating fluids commonly contained within chambered doctor blade units. In some preferred embodiments, the seal ribs may be impregnated with, or their operative arcuate concave sealing surfaces may be coated with, a lubricating composition, which is most preferably oil-or water-based, particularly if the printing or coating fluid being used is water-or oil-based respectively.

As the skilled reader will appreciate from the above, the cartridge unit of the present invention, represents a substantial departure from the intrinsically simple known end seal arrangements, the most basic of which simply involve a pair of wide seals, each of which is secured directly to one or other end of a chambered doctor blade unit, and which, as previously discussed, are inherently prone to both wear and leakage. Firstly, the cartridge unit of the present invention, in its most preferred arrangement, includes a pair of seal ribs in spaced-apart relationship, so that when the cartridge unit is brought into position proximate an Anilox roll and the seal ribs come into contact therewith, not only is the main chamber of the doctor blade unit sealed against some portion of the curved surface of the Anilox roll, but a pair of secondary narrow (i.e. equal to the width between each of the seal ribs in the cartridge unit) chambers is defined, one at either end of the main chamber, and these secondary chambers are also sealed against and by the Anilox roll. Although the provision of double seal arrangements is known, the present invention is distinguished from the prior art configurations and arrangements in a number of important aspects.

Firstly, the or each seal rib contained within the cartridge unit of the present invention is not merely inserted into a recess therein, it is, in essence, quite firmly clamped within the cartridge unit, on either side, and in multiple regions or continuously alongside and proximate at least the uppermost operative sealing surface of the seal ribs (the arcuately concave surface thereof), and in most preferred arrangements, additionally alongside and proximate the inwardly inclined surfaces of the seal rib lying on either side of the operative sealing surface, and which, in use, provide a seat, and thus resilient support for, the ends of the doctor blades disposed theron. Thus by providing such firm axial support for the seal ribs in regions very close to the operative and supporting surfaces of the seal ribs, and on either side, the seal rib operative and inclined supporting surfaces are much less prone to displacement, either rotationally away from their ideal operating position as a result of frictionally induced torques, or axially, as a result of the axially acting pressure of fluid present within the chamber of the doctor blade unit, and which the seal is fundamentally employed to resist. In both cases, the effect is to significantly reduce the propensity of the seal ribs to leak, as well as significantly increasing the dimensional stability of the seal ribs, most importantly in the vicinity of their operative sealing, and inclined, blade-supporting, surfaces.

Furthermore, the configuration and construction of the cartridge unit, once the doctor blades have been removed, allows one or both seal ribs retained within said cartridge unit to be very easily and quickly removed, as the entire unit essentially springs axially apart automatically as and when the retaining bolts holding it together are loosened. Therefore, in order to release, remove and replace the seal ribs, the bolts are only required to be loosened slightly, whereas in practically all prior art arrangements, either the entire seal, or the entire assembly within which the seals are retained, is required to be completely disconnected from the end of the chambered doctor blade unit in which they are disposed. By contrast, the present invention allows for the cartridge unit to remain in place while only the seal ribs are removed.

A yet further advantage of the present invention arises from the use of grub screws as providing the engagement means whereby the side surfaces of the seal ribs are both clamped and gripped within the cartridge assembly. Grub screws are, by their very nature, easily and quickly axially adjustable, and by using, for example, an Allen or hex key, one or more or all of the grub screws provided in any particular end wall or intermediate central wall member can be screwed further into or out of the wall member such that the operative gripping, clamping ends of the grub screws stand project from the side wall surface to a lesser or greater extent as required, and thus the gripping/clamping forceapplied to the side walls of the seal rib(s) can be varied, depending of course on the thickness of the seal rib(s). Thus, by using axially adjustable grub screws, and taking into account the axially adjustable nature of the cartridge unit as a whole, not only can seal ribs of different thickness be accommodated, but also the axial gripping/clamping force applied thereto can be very easily and quickly adjusted. For instance, for certain lower pressure applications, it may be more desirable or only necessary to apply a minimal or relatively low axial grip/clamp pressure to either side of the seal ribs. Alternatively, for higher pressure applications in which the seal ribs are urged into contact with the curved surface of the Anilox roll with greater force, and thus subjected to somewhat greater compressive, frictional and axial fluid pressure forces, it may be necessary to grip/clamp the seal ribs more robustly. The present invention thus allows for significantly greater flexibility as regards both the thickness of the seals which may be employed, and the robustness of their gripping/clamping connection to and within the cartridge unit.

In a further preferred embodiment, the modular seal assembly of the present invention further includes a containment and support unit consisting essentially of a first component of unitary construction and comprising a base portion and an end wall portion projecting perpendicularly upwardly from the base portion, said base portion extending axially away from the end wall portion and having an axial dimension substantially the same as the axial length of the cartridge unit it is adapted to contain and support, and a second end wall component robustly but releasably connected to the base portion of the first component in axial fashion, and thus, together with the end wall portion thereof, said second end wall component defines a channel adapted to receive and contain said cartridge unit when disposed therein. Further preferably, the base portion if the first component is provided with at least pair, and more preferably two pairs, of apertures disposed on either side of the base portion substantially axially symmetrically, and the cartridge unit is connected within the said channel defined between respective end walls of the containment and support unit by means of two or preferably four bolts, the free end of each bolt passing through one said apertures and into appropriately positioned and tapped recesses provided on the base surfaces of one or two of: one or both of the end wall members, and the intermediate central wall member, of the cartridge unit. In a most preferred arrangement, one or more, and preferably two, and most preferably four, springs are disposed between the upper surface of the base portion of first end wall portion of the containment and support unit, and the underside of the cartridge unit disposed within it, such that the cartridge unit is effectively connected to the containment and support unit but the effect of the one or more springs is to bias the cartridge unit away from the containment and support unit such that it is disposed above, for example 2-15mm, above the upper surface of the base portion thereof in floating manner. In a most preferred arrangement, the number of springs corresponds to the number of bolts used to connect the cartridge unit to the containment and support unit, and each spring is preferably cylindrical and of a sufficient diameter to allow the shanks of the bolts to pass therethrough, as is the preferred connection arrangement.

Thus, by providing a modular seal assembly in which the seal-bearing cartridge unit is floatingly mounted, but nevertheless securely connected to the containment and support unit of the assembly, the assembly as a whole allows for much greater control in the pressure of application of the seal ribs within the cartridge unit against the curved surface of the Anilox roll. In particular, this floating mounting arrangement between cartridge unit and containment and support unit permits a much more uniform, even and distributed contact seal pressure as the chambered doctor blade unit as a whole is brought into position against the Anilox roll -by contrast, for prior art seal arrangements in which the seals are generally rigidly directly connected to the chambered doctor blade unit, the seal contact pressure increases directly as a function of the relative proximity of the chambered doctor blade unit as a whole to the Anilox roll, and there is a tendency on the part of operatives, when leakage problems are being experienced, to simply jam the chambered doctor blade unit more tightly up against the Anilox roll. Not only does this action often significantly deform the seals well beyond acceptable limits, and often results in a very uneven sealing pressure distribution over the sealing surface of the seal, but such action can also deform the blade edges against the (very hard) surface of the Anilox roll, leading to yet further leakage issues, and an overall unsatisfactory fluid pressure distribution within the chamber of the doctor blade unit. The present invention however alleviates this issue, by virtue of the fact that the cartridge unit is spring-biased away from, and thus floats somewhat above the containment and support unit by a predetermined amount. Thus, there is a significant amount of vertical and in some preferred embodiments, lateral play between the cartridge unit and the underlying and surrounding containment and support unit, and although the chambered doctor blade can still be moved progressively closer to the surface of the Anilox roll, not only can the cartridge unit and the seal ribs therein find their own (correct) position as the seal ribs come into contact with the correspondingly curved surface of the Anilox roll, the degree to which the seals are compressed thereon and thereby is determined much more by the spring constant of the springs between cartridge unit and containment/support unit, at least to some extent, than by the extent to which an operative tightens, often against prescribed limits, the chambered doctor blade unit against Anilox roll.

In a yet further aspect of the invention, there is provided a modular seal assembly comprising or consisting of at least one cartridge unit which constituted of at least a pair of rigid separate end wall members and at least one intervening rigid seal support member disposed between said end wall members, all of said members being of the same general cross-sectional shape and being connected together in substantially aligned fashion by means of one or more bolts extending through the cartridge unit from one end wall member to the other and passing through the intervening member thus fixing the disposition thereof relative to the adjacent end wall members, said cross-sectional shape having an upper portion which includes at least one arcuately concave edge region, and a base portion which is essentially straight such that over the upper portion, in the axial thickness direction of each member, there is defined a correspondingly arcuately concaved surface, the cross-sectional shape of said intervening member being dimensionally smaller than that of both adjacent end wall members such when assembled, a recess is defined between respective end wall members which extends over at least the arcuately concave surface of the intervening member, said cartridge assembly further comprising at least one resiliently compressible seal rib having a cross-sectional shape substantially corresponding to that of the recess but being of greater depth such that when the seal rib is fully inserted into the recess and comes into contact with the arcuately concaved surface of the intervening seal support member, at least some portion of the seal rib stands proud above the arcuately concaved surfaces of the end wall members lying on either side thereof, Characterised in that Engagement means are provided proximate and substantially alongside at least some portion of the inwardly facing edges of one or both of said end wall members, such that in a first, open condition wherein the one or more bolts are loosened, the end wall members and said engagements means provided proximate the inwardly facing edges thereof are capable of being displaced sufficiently outwardly and away from the intermediate member to release any extant seal rib for removal, and such that, in a second, closed condition wherein the one or more bolts are tightened and the respective side walls of the end wall members and the intermediate member are brought into more proximate relationship, said engagement means engage with and axially compress the seal rib against one or other of: the alternate end wall member, the corresponding inwardly facing edge of the alternate end wall member, or the engagement means provided adjacent and proximate the inwardly facing edge of the alternate end wall member, as the case may be.

Most preferably, the cartridge unit further comprises at least two axial springs, a first axial spring being disposed between an inwardly facing side wall of one end wall member and the respective adjacent side wall of the intervening member, and a second axial spring being disposed between one inwardly facing side wall of the other end wall member and the respective alternate adjacent side wall of the intervening member, such that as the one or more bolts is loosened, said end walls tend to move automatically outwardly under the outward biasing action of said springs.

For the avoidance of doubt, any preferred feature or embodiment aforementioned in connection with the first aspect of the invention should be considered as being equally applicable to any subsequent aspect of the invention, where context and/or configuration permits, and it is merely in the interests of brevity that such features and embodiments are not repeated.

Other advantages and features of the present invention will become apparent from the following specific description, which is provided by way of example with reference to the accompanying Figures hereof, as indicated below.

Brief Description of the Drawings

Figure 1 shows a simple schematic, in end elevation, of the primary components in a conventional (prior art) printing system, Figures 2, 2A shows schematically a perspective view of one end of a prior art chambered doctor blade unit with a single seal in situ therein, and a perspective view of that seal respectively, Figure 3 shows an exploded perspective view of a modular seal assembly according to one aspect of the present invention, and its various component parts, Figure 4 shows a perspective of a modular seal assembly according to one aspect of the present invention having been assembled and in isolation, that is prior to insertion within or connection to a chambered doctor blade unit, Figure 5 shows a perspective view of the main body of chambered doctor blade unit with doctor blade clamps in place but otherwise in isolation, that is without any seals or seal assemblies having been connected to the ends thereof thereto, and without any other extraneous connections or components, Figure 6 shows an alternate perspective view of the main body of the chambered doctor blade unit of Figure 5, with blade clamps removed, and with one modular seal assembly according to one aspect of the present invention in a raised position above one end of the main body as it would be immediately prior to connection to said main body, Figure 7 shows a schematic, partially transparent end elevation view of one on end of a fully assembled chambered doctor blade unit with a modular seal assembly according to one aspect of the present invention in position and connected to the chambered doctor blade unit, together with various other parts, fittings and connections as would be common for a conventional chambered doctor blade unit to have, and Figure 8 shows a schematic, partially transparent end elevation view of the fully assembled chambered doctor blade unit of Figure 7 in its operative position, that is adjacent a portion of the curved surface of a cylindrical Anilox roll.

Detailed Description

Referring firstly to Figure 3, an exploded perspective view of a modular seal assembly is indicated generally at 100, consisting of, on one hand, a cartridge unit indicated generally at bracket 102, and on the other hand, a containment and support unit indicated generally at 104 and, in the figure and in use, disposed substantially beneath and around the cartridge unit.

For the avoidance of doubt, in some embodiments and aspects of the invention, the modular seal assembly may consist only of cartridge unit 102 alone, whereas in other aspects and embodiments, the modular seal assembly may comprise both cartridge unit 102 and containment and support unit 104.

More specifically, containment and support unit 104 consists essentially of a first component 104A being of unitary construction and including a base portion 104C and an end wall portion 104D which projects vertically upwardly from the base portion at one end thereof, and a second end wall component 104B shown in the figure at the other remote end of the assembly. As can be seen in the figure, the upper edge profile of the end wall portions comprises three distinct parts, a pair of inwardly inclined side edges or surfaces 104D-1, 104D-3, and central arcuately concaved surface 104D-2 defined and bounded by correspondingly arcuately concaved edges (not referenced). In most preferred arrangements, edges/surfaces 104D-1, 104D-2 are identical in length and incline, and thus the arcuately concave edge/surface 104D-2 is disposed axially symmetrically and centrally of the first component 104A as a whole. Other configurations are of course possible, and indeed contemplated by the present invention, because for some applications it can be desirable that one or other of the inclined edges/surfaces 104D-1, 104D-3 are of differing lengths and inclinations, and in this case the arcuately concaved edge/surface 104D-2 would of course lie somewhat to one or other side of the central axis 106 of component 104A, and indeed the modular seal assembly as a whole, and/or the apices at which the arcuately concaved edge/surface 1040-2 meets the inclined edges/surfaces 1040-1, 1040-3 may be disposed at differing heights above horizontally orientated base portion 104C.

As can be seen, the free end of base portion 104C terminates in a vertical end surface 104C-1 in which a plurality of drilled and tapped holes 104C-2 are provided to allow correspondingly sized screws 104B-1 (top right in the Figure) to be screwed thereinto and whereby end wall component 104B, in which a corresponding plurality of suitably sized apertures is provided, can be robustly but also releasably secured to the first component 104A, in particular to the free end 104C-1 of the base portion 104C thereof (see also Figure 4). As can also be seen in the figure, two pairs of bolts 108, 110 respectively are shown, and although not specifically referenced in the Figure, suitably located and sized apertures will be provided in the base portion 104C through which the shanks of said bolts can pass prior to their being screwed into the cartridge unit 104 as will be described further below. Also, end wall component 104B is provided with a pair of axially symmetrically disposed cut-outs 104B-2, whose purpose will again be further described below.

Turning now to the cartridge unit 102, this unit comprises multiple different components, namely a pair of end wall members 102A, 102B, an intermediate central wall member 102C, a pair of intervening seal support members 102D, 102E, which are of broadly identical cross-sectional shape to both the end wall members 102A, 102B and the intermediate central wall member 102C, but dimensionally slightly smaller, particularly as regards their depth, a pair of seal ribs 102F, 102G, which are most preferably of a resiliently compressible foam or foam-like material, and a pair of connecting bolts 102H, 1021 by means of which all the respective components of the entire cartridge unit are releasably connected together. As can also be seen in the Figure, the cartridge unit includes three sets of grub screws 102A-1, 102B-1, 102C-2, respectively, each of the plurality of grub screws in each set being received, when the cartridge unit is fully assembled, in corresponding drilled and tapped holes or apertures (not referenced for the sake of clarity, but clearly illustrated in the Figure) provided axially in and preferably completely through respective and corresponding end wall members 102A, 102B, and intermediate central wall member 102C.

To explain the assembly and configuration of the cartridge unit in greater detail, each set of grub screws 102A-1, 102B-1 and 102C-1 is firstly screwed into receiving apertures provided in each of the respective components, specifically end wall members 102A, 102B and intermediate central wall member 102C. In the case of end wall members 102A, 102B, the grub screws are screwed sufficiently into these components so that the majority of their axial length is received within the end wall members and thus only a relatively small portion (maybe of the order of a few mm, e.g. 1-15mm) of the grub screws' length stands proud of the inwardly facing side wall surfaces of those members.

As regards the set of grub screws 102C-1 and their screwed insertion into respective intermediate central wall member 102C, these grub screws are most preferably of an axial length slightly greater than the thickness of intermediate central wall member 102C so that they can be screwed completely into and partially through the other side thereof, the final arrangement being that each grub screw 102C-1 stands proud to some small extent of either and both side wall surfaces of said intermediate central wall member. In most preferred arrangements (though of course not iS necessarily), the amounts by which any and all grub screws stands proud of any side wall surface of the respective member to and within which they are secured is substantially equal.

Once the grub screws 102A-1, 102B-1, 102C-1 are secured in place within respective members 102A, 102B 102C, these members, and the intervening seal support members are brought together into proximate relationship and arranged (usually manually) such that their lowermost straight base surfaces are flush with one another, and their various side wall surfaces are in contact with the corresponding side wall surface of the adjacently disposed component. Although again not specifically referenced in the Figure for the sake of clarity, each component 102B, 102C, 1020, 102E is provided with pairs of suitably sized apertures disposed substantially axially symmetrically of the component, and component 102A is provided with a corresponding pair of tapped recesses or apertures, so that when the various components are brought together as described, said apertures are all substantially aligned. In this condition, bolts 102H, 1021 can be fed into the first pair of such apertures provided in end wall component 102B and then subsequently completely through all the remaining aperture pairs in the other components before finally being screwed into the tapped apertures or recesses provided in end wall component 102A, thus essentially uniting all the various component parts of the cartridge unit 102, excepting the seal ribs 102F, 102G.

In some particular aspects and embodiments of the present invention, two pairs of axial springs 102J, 102K respectively are provided, the first pair 102J being provided between the inwardly facing side surface of end wall component 102A and the adjacently disposed side surface of intervening seal support member 11020, and the second pair 102K being provided between the inwardly facing side surface of end wall component 102B and the adjacently disposed side surface of intervening seal support member 102E. During assembly, the pairs of axial springs are ideally aligned within the apertures or On the case of component 102A) recesses provided in the various components so as to be coaxial therewith, in which condition the shanks of bolts 102H, 1021 pass through said apertures and/or into said recesses as well as through the hollow cores of said axial springs which are thus both held in place by the bolts themselves and trapped and ultimately compressed between the components lying on either side of said axial spring pairs as the bolts are tightened and the cartridge unit is assembled. Thus the tightening action performed on the bolts acts against the natural bias of the springs so that when said bolts are subsequently loosened, the axial springs automatically expand and thus the components on which they act, particularly the end wall members 102A, 102B automatically separate and move away from the intervening seal support member 1020, 102E respectively and with which they are most adjacently disposed, and thus also away from the intermediate central wall member 102C. In a most preferred arrangement, the inwardly facing side surfaces of end wall components 102A, 102B are provided with counterbores coaxial with the said apertures and/or recesses provided in those components and through or into which the bolts pass or are received during assembly of the cartridge unit. Said counterbores are ideally of a diameter marginally greater than the outer diameter of the axial springs so that the springs can be snugly received, and be seated, within said counterbores rendering assembly easier and ensuring that there is no lateral travel of any axial spring over the respective adjacent side surfaces of components 102A, 102D, and components 102B, 102E after the cartridge unit has been assembled.

As the skilled person will understand, once the threaded shank ends of bolts 102H, 1021 begin to engage with the correspondingly threaded recesses or apertures provided in end wall member 102A and have been screwed thereinto by a small amount, the cartridge unit and the various components thereof will be essentially loosely connected together, and there will still remain some axial play of components 102B, 102C, 102D, and 102E relative to end wall member 102A. As the bolts are progressively tightened, naturally the axial play is progressively reduced and said components 102B are progressively urged towards said end wall member 102A. At some point before the bolts are fully tightened however, and all the various components are essentially rigidly clamped against said end wall member 102A, the seal ribs 102F, 102G are inserted into the cartridge unit 102, over respective intervening seal support members 102D, 102E and into the recesses defined between the uppermost surface of said intervening seal support members and the side surfaces of the respective components disposed on either side thereof. Ideally, in the partially assembled condition, the ends of the grub screws which protrude from the side surfaces of the components which respectively partially define each of the seal rib-receiving recess should be sufficiently axially far apart that they do not interfere with the side surface of the seal ribs as they are inserted into the cartridge, or do so to only a very limited extent. As the skilled person will appreciate, as the seal ribs are of a compressible foam or foam-like material, it is certainly possible to insert the seal ribs into the cartridge unit with only minimal deformation, provided the axial separation of respective components, including the axially protruding grub screw ends, is sufficient.

Once the seal ribs 102F, 102G have been fully inserted into their accommodating recesses, and are firmly seated on and supported by the uppermost surfaces of the respective underlying seal support members 102D, 102E (the profile of the seal ribs being essentially identical to or closely matched to the said uppermost surfaces of said seal support members), the bolts 102H, 1021 can then be fully tightened up. This final tightening action completes the assembly of the cartridge unit, in which condition: - The various components of the cartridge unit, in particular their adjacently disposed side surfaces, are all urged by the bolts into firm contact with one another, - The axial springs are compressed within the counterbores (if provided) within which they were initially received and seated, and -The ends of the grub screws which protrude axially away from, and thus stand proud of, respective side surfaces of components 102A, 102C, 102B firmly engage with and (preferably) slightly resiliently deform respective side surfaces of the seal ribs so that they are firmly gripped and clamped in position within their receiving recesses.

Thus in a cartridge unit according to some aspects and embodiments of the invention, not only are the seal ribs firmly gripped on either side, but the gripping/clamping force applied one either side of the seal ribs is uniformly applied, both axially and laterally, as the grub screws are provided On some preferred embodiments) in identical positions along and adjacent the relevant inclined and arcuately concave edges of components 102A, 102B and 102C, and furthermore protrude from and stand proud above the relevant side surfaces of those components by (most preferably) the same extent. Thus not only are the seal ribs firmly retained within the cartridge assembly, but the retaining forces which achieve such retention are very precisely and uniformly applied, over a significant portion of both the operative (arcuately concave) sealing surface, and also (again, in preferred embodiments) some portion, possibly all, of the seal rib lying laterally outwith that operative sealing surface.

In aspects and embodiments of the invention wherein the modular seal assembly includes containment and support unit 104, it is most preferable that the cartridge unit 102 is secured or connected to the containment and support unit in floating fashion, for example by means of vertically disposed cylindrical springs 108A, 110A respectively, through which bolts 108, 110 pass, and which, in the final assembly, are interposed between and act resiliently against, on one hand, the upper surface of base portion 104C of first component 104A of containment and support unit 104, and on the other hand, on the lowermost essentially planar surface of end wall members 102A, 102B, the latter of which (as can be seen in the Figure) are provided with tapped recesses into which bolts 108, 110 can be screwed so that the cartridge unit 102 may be connected, or at least coupled, to the containment and support unit 104. Said bolts 108, 110 would of course also be the primary means whereby the entire modular seal assembly is connected and secured to the particular end of the chambered doctor blade unit of which the seal assembly is to form part. Again, as with other springs provided in the assembly, springs 108A, 110A may be initially received and located in suitably dimensioned counterbores provided coaxially with either the tapped bolt-end receiving recesses provided in the undersides of end wall members 102A, 102B, and/or correspondingly dimensioned and appropriately located apertures provided through the base portion 104C of containment and support unit first component 104A, and through which the shanks of bolts 108, 110 must naturally pass when the cartridge unit 102 is being coupled to the containment and support unit 104 within which it is adapted to be floatingly received and mounted.

As the skilled person will appreciate, once the assembly is complete, the cut-away portions 104B-2 in second component 104B permit ready access to the heads of axially disposed bolts 1021 so that they can be loosened while the cartridge unit 102 is in situ within the containment and support unit 104, and importantly without needing to completely remove the former from the latter. Indeed, this facility provides one of the primary advantages of the present invention, because by loosening bolts 102H, 1021, the respective components of the cartridge unit, in particular end wall member 102A, and intermediate central wall member 102C are automatically, under the outward biasing action of axial springs 102J, 102K, displaced away from end wall member 102A, to which bolts 102H, 1021 remain connected, and the axial grip/clamp exerted on seal ribs102F, 102G by the ends of the grub screws provided in the various components of the cartridge unit is reduced, and most preferably, entirely removed. In this relaxed or "open" condition, the seal ribs can be very easily removed and replaced.

Referring now to Figure 4, one embodiment of the completed and assembled modular seal assembly is shown, with the assembled cartridge unit 102 in place within, and coupled in floating fashion to, the containment and seal unit 104. In particular, the floating nature of the connection between cartridge unit 102 and containment and support unit 104 is such that the base surfaces of the various components which constitute the cartridge unit 102 (all of which most preferably lie flush with one another) are disposed some small distance above the uppermost surface of base portion 104C, as is particularly referenced at 120. This distance may be of the order of a few mm, typically between 1-15mm in a pre-application condition, i.e. before chambered doctor blade unit, to which the assembly is, in use, connected, is brought into its operative position, and the seal assembly is urged against the curved surface of an Anilox roll. As this occurs, the cartridge unit will of course be depressed further and assume a deeper position within the containment and support unit 104, against the action of the vertically disposed springs (not shown in Figure 4, but referenced at 108A, 110A in Figure 3), which of course would become further compressed. It is to be noted that the disposition of the bolts and the springs which they pass through is, in some embodiments, important because the reaction forces of the compressed springs on the cartridge unit are both substantially axially symmetrical of the assembly as a whole, and also act laterally on the cartridge unit at locations which lie laterally beyond the arcuately concave operative sealing surfaces of the seal ribs 102F, 102G. Therefore, in this embodiment at least, the reaction forces applied on the cartridge unit have a stabilising function on the cartridge assembly as a whole and act to resist any frictionally generated torques to which the cartridge unit may be subjected during use.

From Figure 4, it can also be seen that portions of the seal ribs 102F, 102G stand proud above the uppermost surfaces of the respective components of the cartridge unit disposed to one or other side thereof. This is important because when the assembly, in particular the arcuately concave operative sealing surfaces of said seal ribs, is brought into contact with the correspondingly curved surface of an Anilox roll, the seal ribs can be resiliently compressed slightly against the Anilox roll without the Anilox roll otherwise coming into contact with any other component part of the seal assembly, as is of course essential if a robust secure seal therewith is to be achieved without any damage being inflicted thereon. Seal ribs 102F, 102G, similar in profile to the other components of the cartridge unit which lie to one or other side thereof, are provided with inwardly and upwardly inclined surfaces 102F-11, 102F-12, 102G-11, 102G-12 respectively which, as can be seen in the Figure, also stand proud, albeit to a lesser extent, of the adjacent other cartridge unit components, specifically end and intermediate central wall members 102A, 102B, 102C respectively. This arrangement is most preferred because, in use, the axially aligned seal rib inclined surface pairs (102F-11, 102G-11, and 102F-12, 102G-12 respectively) provide resilient support surfaces for the ends of each of the pair of doctor blades (not shown) which are commonly installed and secured to the chambered doctor blade unit, for example by suitable elongate blade clamps extending substantially along the entire length of the apparatus, after modular seal assemblies of the present invention are mounted on and secured to both ends of such apparatus.

Furthermore, in the particular embodiment shown in Figure 4, the relative depths of the end wall portion 104D of the first component 104A of the containment and support unit 104 and the adjacently disposed end wall member 102A can clearly be seen, and in particular, at least the arcuately concave surface of the latter stands proud of the similarly arcuately concave surface of the former by an amount sufficient to expose and thus render accessible the ends of grub screws 102A-1 so that they can be axially adjusted as required. The relatively symmetrical and substantially evenly spaced arrangement of the said grub screws as regards the arcuately concave surface 102A10 of end wall member 102A (and thus, correspondingly, the arcuately concave operative sealing surface 102F-10 of the seal rib 102F) is also to be noted. In particular, it is preferred that a pair of grub screws is provided immediately beneath the apices of the end wall member 102k being those points of the end wall members where the inwardly inclined surfaces 102A-11, 102A-12 meet the terminal ends of the arcuately concave surface 102A-10, as can be seen in the Figure, and at least, one, and preferably three more grub screws is provided in evenly spaced fashion along and immediately underneath the arcuately concave surface 102A-10 between the apices disposed at either end thereof. A similar arrangement of grub screws (although not specifically shown in Figure 4) is preferred for the other components of the cartridge unit, in particular the intermediate central wall member 102C, and end wall member 102B. Preferably, the relative depths of respective components 102B, 104B, on the reverse side of the assembly illustrated in the Figure is similarly configured.

Although in the embodiment shown in the Figure (as compared to that illustrated in Figure 3), not all the grub screws provided in end wall member 102A are exposed and accessible, this need not be the case. For example, in the embodiment illustrated, the two pairs of grub screws which are provided in end wall member 102A laterally beyond arcuately concave surface 102A-10, specifically immediately beneath each of the pair of inwardly inclined surfaces 102A-11, 102A-12 (see Figure 3) are concealed behind the inwardly and upwardly inclined surfaces 104D-1, 104D-3 of component 104D. However, in an alternative embodiment, the relative height of the inclined surfaces 104D-1, 104D-3 may be reduced slightly, as indicated at 104D-1X, 104D-3X such that the ends of those particular grub screws was exposed and revealed, if desired. At the rear of the assembly illustrated in Figure 4, however, it is to be noted that the relative depths of end wall component 104B and end wall member 102B, and in particular their upper surfaces, are such that all the grub screws provided within end wall member 102B are always accessible. There is good reason for this arrangement, because the seal rib 102G will, in use, usually always be subjected to significantly more wear as a result of being the seal against which the pressure of the printing or coating fluid present within the chamber of the chambered doctor blade system directly acts (or at least that portion of this seal rib which stands proud of the end wall member 102B). Thus seal rib 102G can be considered to provide the primary seal, and may thus require replacing more frequently than seal rib 102F, which provides what may be considered a secondary seal with and against the Anilox roll the said seal ribs come into contact with.

Finally, one further feature of the assembly illustrated in Figure 4 is notable, specifically the relative axial snugness of fit of the cartridge unit 102 within the containment and support unit 104, in particular the end wall portion 104D and the second component 104B thereof. In particular, it can been from the Figure that there would appear to be very little, if any, axial clearance between, on the inner side surface of end wall portion 104D and the adjacent side surface of end wall member 102A, and on the other hand, between inner side surface of end wall portion 104B and the adjacent side surface of end wall member 102B. Naturally, in such an arrangement, the extent to which respective components of the cartridge unit which could axially separate from one another as a result of the tendency of the axial springs (102J, 102K, see Figure 3) to axially expand if the connecting bolts (102H, 1021, see Figure 3) were loosened is very limited if not entirely precluded.

In some embodiments, this may be the desired configuration, and the seal ribs may be released from the cartridge unit only by means of axially adjusting the grub screws so that the seal ribs they grip/clamp are released. In this arrangement therefore, it may still be possible to release, remove and replace one or both of the seal ribs without substantially disassembling the assembly, for example by first removing the entire assembly from the chambered doctor blade unit, and then disconnecting the cartridge unit entirely from the containment and support unit, or at removing it completely from within the channel defined within the containment and support unit and within which it conventionally sits. In preferred alternative embodiments however, axial distance between respective opposing inner side surfaces of the vertically upstanding parts (104D, 104B) of the containment and support unit 104 may be greater than the total corresponding axial dimension of the cartridge unit when assembled such that there is a small axial gap between one or both of the end side wall surfaces of end wall members 102A, 102B of the cartridge unit 102, and the respective adjacent side wall surfaces of the containment and support unit. In such a configuration, it would of course be possible to loosen the bolts (102H, 1021, see Figure 3) while the cartridge unit was still in situ within the containment and support unit (i.e. in the position shown in Figure 4), the ultimate effect of which would be that the various component parts of the cartridge unit could axially expand sufficiently to allow one or both of the seal ribs to be released without any need for grub screw adjustment.

Of course, in either of the particular configurations discussed above, it would still be possible to loosen the screws 104B-1 (see Figure 3) so that end wall component 104B could be axially displaced away from the cartridge unit 102, and so that, if bolts 102H, 1021 thereof were also subsequently loosened, the component parts thereof could then, in turn, be axially displaced apart from one another sufficiently to allow one or more of the seal ribs therein to be released, removed, and replaced.

Referring now to the remaining Figures, Figure 5 shows a perspective view of a chambered doctor blade unit, indicated generally at 130 and comprising a main body 132, which is shown with a pair of elongate blade clamps 134, 136 in position (but without any connection means) on either side of the main body and along the uppermost surface of the side walls (not referenced) thereof Although not directly illustrated in the figure, the possible orientation and disposition of the free edges of the pair of doctor blades which the chambered doctor blade apparatus will include is indicated in the Figure by dotted lines 138, 140. As can be seen from these lines, the orientation of the doctor blades is commonly acutely inclined relatively to the substantially horizontal base 142, the degree of such inclination being approximately equal to (or in some cases, 1-5 degrees less) that of the inclined surfaces of the seal ribs when secured within the cartridge unit as above described. Furthermore, the longest free edges of the doctor blades project from the edge of the blade clamps ideally by an amount approximately equal to the length of the correspondingly inclined surfaces of the seal ribs, so that the each of the longest free edges of each doctor blade are substantially coincident with, or slightly overlie, the apices of the seal ribs which support that doctor blade.

Although not specifically illustrated in the Figure, in practice of course, releasable connection means will commonly be provided to releasably secure the blade clamps to the main body, and whereby, upon release, blade clamps 134, 136 can be separated somewhat, for example by rotation, away from the surfaces of the main body over which they are provided, thus releasing the doctor blades they clamp therebetween.

Referring now to Figure 6, the main body 132 of the chambered doctor blade unit is shown, but without blade clamps, and additionally a modular seal assembly 140 according to one embodiment of the present invention is shown at one end of the main body and in a position immediately above that which the assembly will ultimately occupy at that particular end of the main body. Also, from this Figure, the upper surfaces 133A, 133B of main body side walls 133 can be clearly seen, each of which is provided with a blade seat portion 133C, 133D which terminates at a shoulder 133C-1, 133D-1 respectively against each of which one edge of a doctor blade (not shown) is adapted to be abutted, the width of said doctor blade being such that the alternate free edge of the doctor blade overhangs the inward side surface of the respective side wall and adopts the position schematically illustrated in the previous figure. However, before the doctor blades are dropped in place (or inserted between loosened blade clamps and the blade supporting surfaces of seat portions 133C, 133D), modular seal assemblies, such as referenced at 140, and usually in completely assembled condition, are inserted between the main body side walls 133, at each end of the main body, and secured thereto, most commonly using the bolts (108, 110, see Figures 3, 4). Once in position, the inclined surfaces of the seal ribs ideally lie relatively flush with (or in some preferred aspects, slightly proud of, or relatively more steeply upwardly inclined relative to) the seat portions 133C, 133D provided in the upper surfaces of the side walls 133. Regardless of the particular configuration adopted, the ultimate requirement is that the ends of the doctor blades most remote from one another rest on and are supported by at least some portion of the inclined surfaces of both seal ribs present within the modular seal assemblies used.

Referring now to Figure 7 there is shown a schematic partially transparent end elevation view of a chambered doctor blade unit indicated generally at 150 and including a modular seal assembly according to the present invention indicated generally at 140 and including the main body 133 shown in Figures 5 & 6, blade clamps 134, 136 in position and secured firmly to the main body by bolts 152, 154, and by means of which doctor blades 156, 158 respectively are clamped to the main body along one side thereof, with their remaining unclamped portions resting on and thus being supported by respect inclined surfaces of the seal ribs disposed within the modular seal assembly, one of which can be seen in the figure and is referenced at 102G. It is to be noted from the Figure that the remote free edges of the doctor blades 156, 158 are in substantial juxtaposition within the terminated apices (not referenced) of said inclined surfaces of said seal ribs, or even further preferably marginally set back therefrom so that the blade edges lie to the outside of both the arcuately concave operative sealing surfaces of the seal ribs and the termimal apices thereof.

Typically the blade edges may be set back from said apices by a distance ranging from 100 microns to 2000 microns (10 6m). Also shown in this figure various other common connections required for conventional chambered doctor blade apparatus, such as printing or coating fluid inlet and outlet connectors, and various components already discussed above with reference to other Figures.

Reference numerals used on such earlier Figures are retained in this Figure and refer to like components or parts.

Once the chambered doctor blade unit of Figure 7 is completely assembly and ready for deployment, it is arranged against an Anilox roll 170 as schematically illustrated in Figure 8. As can be seen in this Figure, the (positive) radius of curvature of the Anilox roll is at least comparable with, or in some embodiments slightly less than the (negative, i.e. concave) radius of curvature of the arcuately concave operative sealing surfaces of the seal ribs so that there is some osculation betwixt the two curved surfaces, that is of the Anilox and the seal ribs respectively. Of course, there is no critical requirement that the radii of curvature be indentical, only that, when the seal ribs are brought into their operative sealing position against the Anilox roll, and are slightly compressed thereagainst, the nature of the contact region betwixt the two surfaces is osculatory in nature, that is the type of contact achieved between two curved surfaces.

Claims

CLAIMS1. A modular seal assembly comprising at least one cartridge unit which is constituted of at least a pair of rigid separate end wall members and at least one intervening rigid seal support member disposed between said end wall members, all of said members having the same cross-sectional shape and being connected together in aligned fashion by means of one or more bolts extending through the cartridge unit from one end wall member to the other and passing through the intervening member thus fixing the disposition thereof relative to the adjacent end wall members, said cross-sectional shape having an upper portion which includes at least one arcuately concave edge region, and a base portion which is essentially straight such that over the upper portion, in the axial thickness direction of each member, there is defined a correspondingly arcuately concaved surface, the cross-sectional shape of said intervening member being dimensionally smaller than that of both adjacent end wall members such when assembled, a recess is defined between respective end wall members which extends over at least the arcuately concave surface of the intervening member, said cartridge assembly further comprising at least one resiliently compressible seal rib having a cross-sectional shape substantially corresponding to that of the recess but being of greater depth such that when the seal rib is fully inserted into the recess and comes into contact with the arcuately concaved surface of the intervening seal support member, at least some portion of the seal rib stands proud above the arcuately concaved surfaces of the end wall members lying on either side thereof, Characterised in that The cartridge unit further comprises at least two axial springs, a first axial spring being disposed between an inwardly facing side wall of one end wall member and the respective adjacent side wall of the intervening member, and a second axial spring being disposed between one inwardly facing side wall of the other end wall member and the respective alternate adjacent side wall of the intervening member, such that in a first, open condition wherein the one or more bolts are loosened, the end wall members are biased by said axial springs sufficiently outwardly and away from the intermediate member to release any extant seal rib for removal, and such that in a second, closed condition wherein the one or more bolts are tightened and the respective side walls of the end wall members and the intermediate member are brought into more proximate relationship, one or more of: - at least some portion of the inwardly facing edges of the end wall members, and - engagement means, provided on at least one of the inwardly facing side walls of said end wall members and adjacent and proximate at least some portion of their inwardly facing edges, engages with and axially compresses the seal rib against one or other of: -the alternate end wall member, -the corresponding inwardly facing edge of the alternate end wall member, or -the engagement means provided adjacent and proximate the inwardly facing edge of the alternate end wall member.
2. A modular seal assembly according to claim 1 wherein the cartridge unit comprises two bolts disposed preferably substantially laterally symmetrically on either side of the centroids of the end wall and intervening members, and at least 4 axial springs are provided, two of which are disposed between the inwardly facing side wall of one end wall member and the respective adjacent side wall of the intervening member, and the remaining two being disposed between the inwardly facing side wall of the alternate end wall member and the respective adjacent side wall of the intervening member.
3. A modular seal assembly according to claim 3 wherein each of the pair of bolts passes through a corresponding pair of the axial springs disposed in axial alignment on either side of the intervening member.
4. A modular seal assembly according to any preceding claim wherein the inwardly facing side walls of the end wall members are provided with counterbores such that end regions of the axial springs can be at least partially received within said counterbores.
5. A modular seal assembly according to claim 4 wherein the axial springs are circular in cross-section and of a diameter less than that of the counterbores in which end regions thereof are received, such that said axial springs are disposed co-axially with the apertures provided through the end wall members and the intervening member, and through which the shanks of the bolts pass.
6. A modular seal assembly according to any preceding claim wherein the cartridge unit further comprises a rigid intermediate central wall member, and a pair of intervening rigid seal support members disposed on either side thereof such that one intervening member is thus disposed between a first end wall member and one side of the intermediate central wall member, and the other intervening member is disposed between the alternate end wall member and the other side of the intermediate central wall member, said rigid intermediate central wall member having the same cross-sectional shape as the end wall members and the intervening members such that, when assembled, a pair of recesses is defined between the intermediate central wall member and respective end wall members, one on each side of the intermediate central wall member, said recesses extending over at least the arcuately concave surfaces of each of the intervening seal support members provided on either side of the intermediate central wall member.
7. A modular seal assembly according to claim 6 wherein the cartridge assembly further preferably comprises a pair of resiliently compressible seal ribs having identical cross-sectional shapes substantially corresponding to that of each of the recesses, each of said pair of seal ribs being of greater depth than the recesses in which they are disposed such that when the seal ribs are fully inserted into the recesses and come into contact with the arcuately concaved surface of the respective intervening members, at least some portion of each seal rib stands proud above the arcuately concaved surfaces of the end wall members and intermediate central wall member lying on either side of the seal ribs.
8. A modular seal assembly according to claim 7 wherein one or more of: -one or both of the inwardly facing side walls of the end wall members, and -one or both of the side walls of the intermediate central wall member, are provided with engagement means disposed proximate at least some portion of the arcuately concave edges of said members, such that said engagement means axially engages with and then compresses a side surface of that seal rib disposed immediately adjacent thereto when the bolts are tightened and the various members of the cartridge assembly are brought into axially closer relationship.
9. A modular seal assembly according to claim 8 wherein the engagement means are in the form of a plurality of discrete pins.
10. A modular seal assembly according to claim 8 or claim 9 wherein the cartridge unit is provided with an intermediate central wall member and engagement means are provided on both side walls thereof proximate the arcuately concave edges thereof.
11. A modular seal assembly according to claim 10 wherein the engagement means take the form of grub screws having a length greater than the axial thickness of the intermediate central wall member such that they can be screwed into and through tapped holes provided therein to such an extent that a portion of each grub screw stands proud of each side wall of said intermediate central wall member.
12. A modular seal assembly according to any of claims 8-11 wherein all or a majority of engagement means provided in respective laterally oppositely disposed components are one of: - axially aligned - disposed in axially offset relationship. 5
13. A modular seal assembly according to any preceding claim wherein the seal ribs are constituted of a resiliently compressible foam material, and are either impregnated with, or their operative arcuate concave sealing surfaces may be coated with, a lubricating composition which is oil-or water-based depending on whether the coating or printing fluid is water-or oil-based respectively.
14. A modular seal assembly according to any preceding claim further comprising a containment and support unit having of a first component of unitary construction and comprising a base portion and an end wall portion projecting upwardly from the base portion, said base portion extending axially away from the end wall portion and having an axial dimension substantially the same as the axial length of the cartridge unit it is adapted to contain and support, and a second end wall component releasably connected to the base portion of the first component in axial fashion, such that together with the end wall portion thereof, said second end wall component defines a channel adapted to receive and contain said cartridge unit when disposed therein.
15. A modular seal assembly according to claim 14 wherein the base portion of the first component is provided with at least pair of apertures disposed on either side of the base portion in axially symmetric fashion, the cartridge unit being connected within the channel defined between respective end walls of the containment and support unit by means of a number of bolts corresponding to the number of said apertures, the free end of each bolt passing through one of said apertures and into appropriately positioned and tapped recesses provided on the base surfaces of one or two of: - one or both of the end wall members, and -the intermediate central wall member, of the cartridge unit.
16. A modular seal assembly according to claim 15 wherein at least two springs are disposed between the upper surface of the base portion of the first end wall portion of the containment and support unit, and the underside of the cartridge unit disposed within it, such that said cartridge unit is effectively connected to the containment and support unit but the effect of said at least two springs is to bias the cartridge unit away from the containment and support unit such that it is disposed above the upper surface of the base portion thereof in floating manner.
17. A modular seal assembly comprising at least one cartridge unit which is constituted of at least a pair of rigid separate end wall members and at least one intervening rigid seal support member disposed between said end wall members, all of said members being of the same cross-sectional shape and being connected together in substantially aligned fashion by means of one or more bolts extending through the cartridge unit from one end wall member to the other and passing through the intervening member thus fixing the disposition thereof relative to the adjacent end wall members, said cross-sectional shape having an upper portion which includes at least one arcuately concave edge region, and a base portion which is essentially straight such that over the upper portion, in the axial thickness direction of each member, there is defined a correspondingly arcuately concaved surface, the cross-sectional shape of said intervening member being dimensionally smaller than that of both adjacent end wall members such when assembled, a recess is defined between respective end wall members which extends over at least the arcuately concave surface of the intervening member, said cartridge assembly further comprising at least one resiliently compressible seal rib having a cross-sectional shape substantially corresponding to that of the recess but being of greater depth such that when the seal rib is fully inserted into the recess and comes into contact with the arcuately concaved surface of the intervening seal support member, at least some portion of the seal rib stands proud above the arcuately concaved surfaces of the end wall members lying on either side thereof, Characterised in that Engagement means are provided proximate and substantially alongside at least some portion of the inwardly facing edges of one or both of said end wall members, such that in a first, open condition wherein the one or more bolts are loosened, the end wall members and said engagements means provided proximate the inwardly facing edges thereof are capable of being displaced sufficiently outwardly and away from the intermediate member to release any extant seal rib for removal, and such that, in a second, closed condition wherein the one or more bolts are tightened and the respective side walls of the end wall members and the intermediate member are brought into more proximate relationship, said engagement means engage with and axially compress the seal rib against one or other of: -the alternate end wall member, -the corresponding inwardly facing edge of the alternate end wall member, or -the engagement means provided adjacent and proximate the inwardly facing edge of the alternate end wall member.
18. A seal assembly according to claim 17 wherein the cartridge unit further comprises at least two axial springs, a first axial spring being disposed between an inwardly facing side wall of one end wall member and the respective adjacent side wall of the intervening member, and a second axial spring being disposed between one inwardly facing side wall of the other end wall member and the respective alternate adjacent side wall of the intervening member, such that as the one or more bolts is loosened, said end walls tend to move automatically away from one another under the biasing action of said springs thus releasing the sealing rib.