APPLICATION OF LIQUID UTILISING A CONTROLLED GAS SUPPLY

Abstract: A process for applying liquid to a surface wherein application of the liquid is determined in accordance with a predetermined pattern of application by selective control of multiple gas charges directed into a region into which liquid is introduced by supplying liquid to the openings of an ordered array of apertures extending between the major surfaces of a grid which is moved past and relative to the sources of the gas charges whereby at least some of the charges register in turn with individual apertures in the grid. The selective control is such that respective charges of gas eject liquid from respective registering apertures in the grid. Apparatus for carrying out the process includes an array of orifices (14); a grid (18) with an ordered array of uniform apertures (34) extending between its major surfaces (18a, 18b) means (36) for supplying liquid to the apertures, means (22, 24) to move the grid (18) in front of the orifices (14) so that orifices (14) register in turn with individual apertures (34) of the grid (18); and remote controllable valves (30) in gas lines (28) communicating with the orifices (14), which valves (30) are selectively actuable to cause respective charges of gas to issue from the orifices (14) so as to eject liquid from respective registering apertures (34) of the grid (18), and thereby to determine application of said liquid to a surface in accordance with a predetermined pattern of application.

Description: "APPLICATION OF LIQUID UTILISING A CONTROLLED GAS SUPPLY" TECHNICAL FIELD This invention relates broadly to the application of liquid to a surface and is concerned particu¬ larly, though not exclusively, with process and apparatus having special utility in the treatment of strip textile fabric, including pile fabric such as carpet, ari . of vinyl strip. The strip may be continuous or discontinuous, as would be the case, for example, with carpet tiles. BACKGROUND ART Recent years have seen the development of several carpet printing techniques based on the principle of selectively applying a multiplicity of streams of dye liquor to a passing web or strip of carpet in such a manner as to produce a sharply defined pattern having a uniformly reliable colour distribution. A suitable electronic control for the dye streams may be programmed to trigger the sequence of application of the dye streams required to produce any desired pattern. There have been a number of proposals for generating and controlling the individual dye streams in the practical application of such techniques. Australian patent 488714 is one of a series which together described a technique of the above kind in which continuously issuing dye streams are normally OMPI * ^ -- deflected by air jets into an adjacent trough for recirculation. Impingement of a dye stream onto an underlying web or pile of carpet is effected by closing the individual valve controlling the associated air jet to allow the dye stream to be directed onto the carpet without deflection. United States Patent 3393411 discloses an arrangement in which control of each dye stream is by way of a solenoid or pinch valve in the feed tube leading to the respective nozzle. Quick response at the nozzle is achieved by the retention of fluid by capillary action in the tube between the valve and the nozzle orifice when the valve is closed. In this context, and in the context of the present specification, the term "nozzle" embraces a mere outlet orifice from a liquid manifold or supply duct. Direct supply of dye liquor from the feed tubes on¬ to the -underlying moving strip is also described in United States patent 2218811 in connection with the dyeing of fabrics. Here, a line of nozzles is fed from a plurality of dye tanks via simple hand valves and distributor pipes associated with each tank. Applicant's co-pending Australian application 47495/79 discloses a refinement of this arrangement which employs a bank of distributors and associated remote controllable valves. Attempts to apply the various arrangements described to the pattern dyeing of fabric in general or of impervious media such as vinyl have been unsuccessful. The fineness of detail and degree of resolution required is substantially greater than for carpets, where the pile form of the material inevitably lowers expectations. The difficulties arise principally from the inherent slow response of mechanical valve devices and/or from lower limit constraints on the gauge of nozzles for liquid ejection and on the size of coherent liquid droplets. On the other hand, it is known from the experience with carpets that multiple stream dyeing has clear advantages over traditional techniques. The pattern is controlled electronically so that there are no individual colour screens as in conventional printing, thus largely obviating storage and handling problems. Rapid pattern changes are possible and good dye penetration is achieved. An arrangement for producing a random coloration on a travelling sheet, viz a mottled, strippled or like decorative effect is disclosed in United States patent specification 3529992. Here, dye retained in a moving metal mesh is entrained by .a single traversing air nozzle and thereby applied to a travelling sheet. Dye is applied to the metal mesh by a pad roller arrangement and the sheet is preferably subjected to indexed movement. The possibility of using multiple gas streams is canvassed but the traversing air nozzle is preferred. In a somewhat different field, United States patent specification 3600834 is concerned with forming a temporary display, which presumably might be used as a stencil, on a moving strip. The strip comprises a mesh of any suitable plastics glass or metal configuration which takes up liquid composition in a bath. Multiple air nozzles associated with character generating circuitry remove dye from the mesh and so generate a chosen character display on the mesh. The removed dye is returned to the bath. United States patent specification 3978695 describes apparatus for dyeing a travelling yarn in which dye is entrained by an air stream moving normal to the dye stream, the air/dye mix then traversing the yarn, which travels on a line normal to the separated dye and air streams. DISCLOSURE OF THE INVENTION It is an object of the invention to provide improve apparatus and process for applying liquid to a surface which " maintains the advantages of the multiple dye stream technique and yet allows finer patterns to be achieved. According to the invention, there is provided apparatus for applying liquid to a surface, comprising:- an array of multiple orifices; means to introduce liquid into a region in front of said orifices; and multiple remote controllable valve means disposed in gas flow lines communicating with said orifices, which valve means are selectively actuable by a programmable electronic control to cause respect¬ ive charges or streams of gas to issue from the :.i orifices, and thereby to determine application of said liquid to a surface in accordance with a predetermined pattern of application; characterized in that said liquid introducing means comprises a grid having an ordered array of substantially uniform discrete apertures extending between its major surfaces, means for supplying liquid to said apertures and means to move said grid through said region relative to said array of orifices whereby at least some of the orifices register in turn with individual said apertures of the grid; and in that said valve means is selectively actuable to cause respective charges or streams of gas to issue from the orifices so as to eject liquid from respective registering apertures of the grid. - Ό EAIΓ 0 P1 The grid advantageously comprises a hollow cylindrical body perforated to provide said apertures and rotatable by said grid moving means. The liquid supply means preferably comprises a supply housing open to and substantially sealingly applied against a major surface of the grid. The orifices may be nozzles disposed such that the grid passes in close proximity thereto. Suction means may be disposed opposite said orifices so as to be on the remote side of a strip carried by conveyor means for guiding a strip past said orifices, said orifices being arranged transversely of the conveyor means. The invention also provides a process of applying liquid to a surface wherein application of the liquid is determined in accordance with a predetermined pattern of application by selective control of multiple gas chaarges or streams directed into a region into which liquid is introduced, characterized in that said liquid is introduc- ed by supplying liquid to the openings of an ordered array of substantially uniform discrete apertures extending between the major surfaces of a grid which is moved past and relative to said sources of said gas charges or streams whereby at least some of the charges or streams register in turn with individual apertures in the grid, and in that said selective control is such that respective charges or streams of gas eject liquid from respective registering apertures in the grid. BRIEF DESCRIPTION OF DRAWINGS The invention will be further described, by way of example only, with reference to the accompanying schematic drawings, in which: Figure 1 is a side view of a liquid appli¬ cator station according to the invention for applying liquid such as dye liquor to a passing web of fabric or vinyl Figure 2 is a cross section on the line 2 - 2 in Figure 1; BEST MODE OF CARRYING OUT THE INVENTION AND INDUSTRIAL APPLICABILITY In a typical treatment plant incorporating the invention a continuous strip 10 of textile fabric, whic may be pile material such as carpet, or of vinyl is guided on a conveyor mesh 9 past . a sequence of spaced liquid applicator stations such as the representative station indicated at 12 in Figures 1 and 2. The stations are essentially of identical structure and, in a typical treatment program might apply to the strip respective dye liquors of particular colour to achieve a chosen multi-colour pattern. Alternatively, one or more stations might apply respective dye liquors and others an underlay or overlay of gum for particular colouration effects. In a full industrial plant, there might be six to eight, or even more, liquid applicator stations spaced along the conveyor, which would also carry the treated strip to other treatment stations such dye fixing chambers and vacuum extractor units. The principal elements of station 12 are a linear array of multiple orifices in the form of air jet nozzles 14 directed towards the conveyor and arranged transversely thereof along a centre line of the applicator station, and, for the purpose of introducing liquid into a region in front of the nozzles, a grid defined by a multi-apertured hollow cylindrical body or drum 18. Drum grid 18 defines inner and outer major cylindrical surfaces 18a, 18b which respectively almost contact or lightly contact nozzles 14, and lie just above the strip as it. travels along conveyor 9. Drum grid 18 may be of thickness, for example, in the range 1 to 10mm and of length matching the width of the strip to be treated. For carpet a length up to 5m . may be required. Nozzles 14 are suspended from a mounting beam 20 or like support which extends the length of the interior of the drum and is supported beyond the drum's open ends. Drum grid 18 is rotatably support¬ ed by any suitable means (not shown) and is dr-vingly coupled by way of, for example,friction wheels or gears 22 to a motor 24 arranged to revolve the drum at a substantially uniform adjustable speed. The line of nozzles 14 is not necessarily at right angles to the direction of movement of the conveyor and may be at a substantial angle thereto if such is expedient. Each of the nozzles communicates with a supply 26 of compressed air by way of gas flow lines 28, subject to the condition of respective remote controllable valves 30 associated with the nozzles. Valves 30 may be, for example, solenoid valves and may be located within drum grid 18, as shown, or externally of the drum. Valves 30 are selectively actuable by an external programmable electronic control 32, control signals being transmitted to the valves on cables or wires 33 which pass through the open ends of drum grid 18. The apertures of drum 18_ comprise an ordered array of substantially uniform, discrete, preferably circular apertures 34 (Figure 2 ) which extend radially between the major surfaces 18a, 18b of the drum. Typically, this array may consist of multiple uniformly spaced circumferentially extending -parallel lines of uniformly spaced apertures. There may be advantage in arranging the apertures in staggered lines to maximise their separation. Apertures 34 and nozzles 14 are arranged so that as the drum grid is moved between and relative to the conveyor and the array of nozzles, at least some of the nozzles register in turn with individual apertures 34 of the grid. In most cases, the gauge of the nozzles coincides with the longitudinal gauge of-the circumferential lines of apertures, and these lines pass directly under respective nozzles. The gauge involved may, for example, be 2 to 5mm, with aperture and nozzle diameters then being of the order of 0.25 to 2.5mm. It is to be understood in the latter connection that registry of a nozzle and an aperture does not necessarily imply that they are of similar diameter. It is also to be emphasized that the apertures may be arranged in two or more arrays in which the apertures are uniform but as between which they are not. Treatment liquid, for example, dye liquor, is supplied to the apertures 34 of drum grid 18 by way of a pressure impregnation device 36 fixed in place within the drum (by means not shown) . Device 36 comprises a longitudinal trough-like housing 38 which is open to and substantially sealingly applied against the inside major surface 18a of the drum. The rims of the housing carry resilient beads 37 and means (not shown) is provided to clamp the housing against the drum. Housing 38 receives liquid under pressure via conduit 41 from a supply reservoir 40, whereby the liquid is forced into apertures 34 as the drum rotates past housing 38. Pressure impregnation device 36 is associated with a wiper blade 44 which removes excess liquid from the outside of the drum below the impregnation device- for collection in a waste trough 46. This ensures that only metered charges of liquid travel towards the nozzles 14, retained in apertures 34 by surface tension/capillary effects. In operation of the applicator station, ^ treatment liquid is supplied at pressure impregnation device 36 to the apertures 34 of drum grid 18. As the filled apertures pass the nozzles 14, valves 30 are selectively actuated by programmable electronic con¬ trol 32 to cause respective charges or streams of air to issue from the nozzles 14 into respective register¬ ing apertures of the grid, whereby to eject the liquid charges contained in the apertures onto the passing strip on conveyor 9 in accordance with a predetermined pattern of application stored in control 32. Control 32 is clocked by a transducer -47 which senses the speed of rotation of drum grid 18. The timing of valve actuation to occur precisely at nozzle-aperture coincidence can be approximately set from the known physical relationship between the position of transducer 47 , the aperture array and the location of the nozzles, but control 32 preferably incorporates provision for fine timing adjustment to obtain substantially exact synchronization. Control 32 may be of any one of a variety of suitable y_ V- _o:-,r?ι ; wIiF-rOυ computer-based systems previously applied to known multiple nozzle liquid application plants, with appropriate software adaptation to the present arrangement. It typically co-ordinates all applicator stations of the plant. Valves 30 preferably operate ON-OFF for each aperture to be cleared, even when successive apertures are involved. For optimum operation, it is also desirable that the air stream or charge emitted from each nozzle 14 presents to the register¬ ing aperture 34 so that it just dislodges the charge of liquid in the aperture onto the passing fabric as a fine compact droplet. Thus excessive air pressure in lines 28 will give rise to excessive dispersion of the liquid charges, and to a consequent degradation of droplet formation on the converged strip. Fineness of pattern resolution, and accuracy of liquid application,is also aided by close proximity of the strip to the drum along the line of application of the dye, as this minimizes centrifugal effects arising from the rotation of the drum. It will be appreciated that the optimum air pressure applied to an aperture to achieve satisfact¬ ory ejection of its charge of liquid will also depend to an extent on the speed of rotation of the drum and upon the viscosity of the liquid. Thus, speed of rotation of the drum relative to speed of travel of the strip can also be adjusted to vary droplet resolution on the strip: a sufficiently slow speed will achieve linear patterns as required. The drum preferably, but not necessarily, rotates such that at the nozzles, it is moving in the same direction as the conveyor, it may be driven continuously or be subjected to a slightly stepped motion synchronized with valve actuation. Another variable which must be taken into account is the degree of penetration of the conveyed strip which is required. In the case of woven fabric, and even more so with impervious media such as vinyl, only minimal penetration is desired, and it is then necessary to minimize air pressure and aperture size to prevent undue spreading of the droplets of liquid. On the other hand, pile material requires substantial penetration, suggesting larger apertures for greater liquid volume per droplet,and increased air pressure. Indeed it may be of assistance to provide a vacuum slot 48 opposite nozzles 14 (Figure 1) on the remote side of the conveyor for applying suction to the liquid into the pile and to centralize and draw off the air pulse. Alternative grid configurations- include a honeycomb structure defining apertures of hexagonal cress-section. Alternative means of supplying liquid to the grid include a trough into which the grid dips as it moves or a blade damming a liquid reservoir within the rotating drum grid. These alternatives are by no means exhaustive.

Claims: CLAIMS : - 1. Apparatus for applying liquid to a surface, comprising:- an array of multiple orifices; means to introduce liquid into a region in front of said orifices; and multiple remote controllable valve means disposed in gas flow lines communicating with said orifices, which valve means are selectively actuable by a programmable electronic control to cause respective charges or streams of gas to issue from the orifices, and thereby to determine application of said liquid to a surface in accordance with a predetermined pattern of application; characterized in that said liquid intrerducing means comprises a grid having an ordered array of substantially uniform discrete apertures expending between its major surfaces, means for supplying liquid to said apertures and means to move said grid- through said region relative to said array of orifices whereby at least some of the orifices register in turn with individual said apertures of the grid; and in that said valve means is selectively actuable to cause respective charges or streams of gas to issue from the orifices so as to eject liquid from respective registering apertures of the grid. 2. Apparatus according to claim 1 further characterized in that said grid comprises a hollow cylindrical body perforated to provide said apertures and rotatable by said grid moving means. - UREAi 0MP1_ 4 . wi p o 3. Apparatus according to claim 1 or 2 further characterized in that said orifices are nozzles disposed such that the grid passes in close proximity thereto. 4. Apparatus according to claim 1, 2 or 3 further characterized in that the liquid supply . means comprises a supply housing open to and sub¬ stantially sealingly applied against a major surface of the grid. 5. Apparatus according to any preceding claim further characterized by conveyor means for guiding a strip past said orifices, said orifices being arranged transversely of the conveyor means. 6. Apparatus according to claim 5 f rther characterized by suction means disposed opposite said orifices so as to be on the remote side of the strip. 7. Apparatus according to claim 5 or 6 further characterized by a plurality of said array of multiple orifices and said grid, spaced along the conveyor means in its direction of travel. 8. Apparatus according to any preceding claim further characterized in that there is further provided a multiplicity of fluid distributors in said gas supply lines between the valve means and said orifices whereby each valve means controls gas issue from a respective group of associated orifices so arranged in relation to the other groups that one or more repeats of said pattern occur across said surface and in that the supply lines connecting the orifices of each group to its distributor are of substantially equal length. 9. A process of applying liquid to a surface wherein application of the liquid is determined in accordance with a predetermined pattern of application by selective control of multiple gas charges or streams directed into a region into which liquid is introduced, characterized in that said liquid is introduced by supplying liquid to the openings of an ordered array of substantially uniform discrete apertures extending between the major surfaces of a grid which is moved past and relative to said sources of said gas charges or streams whereby at least some of the charges or streams register in tu-tfnwith •■ individual apertures in the grid, and in that said selective control is such that respective charges or streams of gas eject liquid from respective registering apertures in the grid.

Inventors: BARTLETT I, MCKENDRICK G
Applicants: BARTLETT I, MCKENDRICK G, TYBAR ENG PTY LTD
Application year: 1980
Main classification: D06B1
IPC codes: D06B11