Abstract:
A self cleaning header assembly for use within a spray application system includes a plurality of spray guns for spraying a mix of air and liquid, e.g., an adhesive, and comprises a cleaning mechanism including one or more wash nozzles and a shroud. During a cleaning cycle, the shroud is closed and the spray guns rotate to approach the wash nozzles. The wash nozzles apply pressurized liquid, e.g., water, to the spray gun nozzles to remove excess adhesive that may affect the spray pattern and flow. After the washing cycle is complete, the spray guns are rotated to again face the target of interest and the shroud is reopened.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 61/089,254, filed Aug. 15, 2008, which is incorporated herein in its entirety. 
     
    
     BACKGROUND 
       [0002]    In the production of materials, it is often necessary to adhere one piece of material to another. This is very often the case in the production of sheet-like materials, wherein laminating is used to improve the physical properties or appearance of the finished product. One problem that arises in such situations is that it is necessary to apply an adhesive to one or both surfaces, and yet adhesives, by their nature tend to be, or to become, sticky and viscous, thus eventually clogging the machinery used to apply such adhesives. 
         [0003]    Although it is possible to remove and clean or replace the affected portions of the system, this entails labor and material costs, and also results in excessive downtime of the production line. While the present invention also may entail certain costs and may result in a small amount of downtime, it very often provides a significantly more economical solution than the state of the art. 
         [0004]    When considering this background section, the disclosure and claims herein should not be limited by the deficiencies of the prior art. In other words, the solution of those deficiencies, while desirable, is not a critical limitation of any claim except where otherwise expressly noted in that claim. Moreover, while this background section is presented as a convenience to the reader who may not be of skill in this art, it will be appreciated that this section is too brief to attempt to accurately and completely survey the prior art. The preceding background description is thus a simplified and anecdotal narrative and is not intended to replace printed references in the art. To the extent an inconsistency or omission between the demonstrated state of the printed art and the foregoing narrative exists, the foregoing narrative is not intended to cure such inconsistency or omission. Rather, applicants would defer to the demonstrated state of the printed art. 
       SUMMARY OF THE INVENTION 
       [0005]    In one aspect, it is an object of the invention to provide an apparatus and method for automatically cleaning a nozzle array with minimal downtime incurred, and without requiring disassembly of the spray head or spray system. 
         [0006]    It is a further object of the invention to provide an adhesive application system having self-cleaning spray nozzles, such that the nozzles may be cleaned without removing them and without contaminating the target. 
         [0007]    It is yet another object of the invention to provide an apparatus and method for automatically cleaning a nozzle, wherein the actuation of a cleaning mode serves to both clean the nozzles and enclose the spray guns. 
         [0008]    Further objects and advantages will be appreciated from the included detailed description and figures. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1  is a system schematic view of a foam lamination system in accordance with an embodiment of the invention; 
           [0010]      FIG. 2  is a cut away perspective end view of a self cleaning header assembly in accordance with an embodiment of the invention; 
           [0011]      FIG. 2   a  is a further cut away perspective end view of a self cleaning header assembly in accordance with an embodiment of the invention; 
           [0012]      FIG. 3  is a perspective end view of a self cleaning header housing in accordance with an embodiment of the invention; 
           [0013]      FIG. 3   a  is a schematic perspective end view of a mounting system in accordance with an embodiment of the invention; 
           [0014]      FIG. 4  is a cross-sectional end view of a self cleaning header assembly in accordance with an embodiment of the invention; 
           [0015]      FIG. 5  is a further cross-sectional end view of a self cleaning header assembly in accordance with an embodiment of the invention; and 
           [0016]      FIG. 6  is a cross-sectional of a spray gun assembly in accordance with an embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0017]    Turning to  FIG. 1 , a foam lamination system  100  is shown. The exemplary foam system  100  includes one or more self cleaning header assemblies  102  including a plurality of spray guns  104  for spraying a mix of air and liquid, such as an atomized mix of air and adhesive for use in pulp and paper manufacturing. Each spray gun  104  includes an internal wash passageway  106  for cleaning the spray gun interior. To eliminate exterior buildup, each header assembly  102  further comprises one or more external wash nozzles  108 . The system further includes an air supply module  110  that supplies atomizing air and cylinder air to each of the spray guns  104  via their respective supply lines. The water supply module  112  and adhesive supply module  114  deliver water and adhesive, respectively, to the spray guns  104 . The water supply module  112  also delivers water to the external wash nozzles  108  for cleaning the exterior of the spray guns  104 . 
         [0018]    Turning to  FIG. 2 , an embodiment of a self cleaning header assembly  102  is shown. The header assembly  102  houses a plurality of spray guns  104  mounted to a manifold  200 . In an embodiment the spray guns  104  are plate mounted on the manifold  200  to facilitate assembly and replacement procedures. Preferably, the manifold  200  is completely enshrouded by header covers  202  for protecting the spray guns  104 . The spray guns  104  disperse the atomized mix of air and liquid (e.g., adhesive) via a header slot  204  when the manifold  200  is in the active position  206 . Thus, when the manifold is in the active position  206 , the spray guns disperse the atomized mix along the y-axis, as shown. The header slot  204  is located along a front plane of the header assembly  102 . The nozzles of the spray guns  104  are presented to the header slot  204  so as to minimize the buildup of residue. 
         [0019]    In order to clean the exterior surface of the spray gun nozzles  208 , the manifold is rotated clockwise via a set of gears  210 ,  212  into a washdown position  214 , wherein the nozzles  208  of the spray guns  104  point to the upper cover of the header assembly  102  (along the rotated y-axis in position  214 ) to face one or more external wash nozzles  108  (shown in  FIG. 5 ) that are rigidly mounted on the upper cover of the header assembly  102 . As shown in  FIG. 2A , when the manifold  200  rotates clockwise into the washdown position  214 , the shutter  216  moves counterclockwise to close the space defined by the header slot  204 . 
         [0020]    In one embodiment, illustrated in  FIG. 3 , the manifold  200  is rotated from either end of the header assembly  102  via a rotary actuator  300  (e.g., a motor) coupled to a manifold gear  210  ( FIG. 2 ). Preferably, all rotating machinery is located in the bottom portion of the header assembly  102  so that the top portion can be removed without disassembling the moving portion of the mechanism. Furthermore, the outside contour  302  of CIP header assembly  102  is designed to accommodate web travel at multiple angles to provide best coverage, as well as to facilitate cleanup and minimize exposed tubing and fittings. The cross section of the header assembly  102  is minimized in order to fit in tight spaces. Preferably, the header assembly  102  is capable of mating with one or more additional header assemblies end-to-end to multiply coverage (e.g., double the coverage in case of two header assemblies mounted end-to-end). Additional header assemblies may be mounted on either end of the header assembly  102 . 
         [0021]    Labyrinthine design of the header assembly  102  prevents dripping during washdown (i.e., when the manifold  200  is in position  214  facing external wash nozzles  108 ) without the need for seals. The header assembly  102  is designed such that the spray guns  104  can rotate and shutter  216  can be closed without changing the side footprint of the overall assembly. This eliminates mechanical interference with the web during washdown. In one embodiment, the components of the header assembly  102  and manifold  200  are made from extruded metal and can be cut to various lengths for custom installations. As shown in  FIG. 3A , a T-slot  304  in top of manifold  200  allows attachment of spray guns  104  from above the manifold, while screw bosses and extrusions open away from wetted areas to minimize potential for leaks. To simplify the manufacturing process and to minimize external tubing and fittings, the water passage for external wash nozzles  108  is incorporated into the upper extrusion. Furthermore, the upper extrusion is easily removable when access to the spray guns  104  is needed. To this end, spray guns  104  are attached to the manifold  200  with clamps and T-nuts to facilitate removal from above the manifold. The fluid connections to the extruded manifold  200  are bolted onto the manifold and can be positioned anywhere. Preferably, the fluid connections are reversible so that they could be plumbed from either side of the manifold. 
         [0022]      FIGS. 4 and 5  illustrate cross-sectional views of the header assembly  102 , manifold  200 , and spray gun  104  when the manifold  200  is in the active position  206  ( FIG. 4 ) and washdown position  214  ( FIG. 5 ) respectively. As shown in  FIG. 4 , when the manifold  200  is in the active position  206 , the nozzle  208  of the spray gun  104  is able to disperse the atomized mix through the open header slot  204  because the shutter  216  is open and the nozzle  208  is facing the slot opening. Optionally, the shutter  216  is supported by a shutter bracket  400  for ensuring a rigidity of the shutter  216  along the length of the header assembly  102 . As shown in  FIG. 5 , when the rotary actuator  300  is activated (e.g., on-demand or during predetermined maintenance periods), the shutter  216  closes the slot opening  204  and the manifold  200  moves into a washdown position  214  where the nozzle  208  of the spray gun  104  is facing the external wash nozzle  108 . At this time, the external wash nozzle  108  is activated to remove the residue buildup from the exterior of the spray gun  104 , including its nozzle  208 . 
         [0023]    Turning to  FIG. 6 , a cross-sectional view of the manifold  200  and spray gun  104  is shown in further detail. In a conventional manner, the spray gun  104  begins spraying when the needle valve  600  moves back responsive to the cylinder air being pumped in via the cylinder air input  602  to cause the piston  604  to compress the cylinder  606 . Preferably, the internal air passages  608  are rinsed from a separate water port  610  in the gun body in order to force any accidental adhesive out of the air passages. Duckbill check valves  612 - 616  incorporated into the gun body prevent air, water and adhesive from contaminating the other passages in the supply manifold and act as the face seal for the adhesive in, atomizing air, and wash water passages  620 - 624 . Duckbill check valve  618  is used to prevent any contamination from the adhesive return passage  626  in the manifold body. However, in an embodiment of the invention, the check valve  618  is omitted. 
         [0024]    Manifold passages  602 ,  620 ,  622 ,  624 , and  626  accommodate cylinder air, adhesive in, atomizing air, internal water flush, and adhesive return respectively. Manifold passages  602 ,  620 - 626  provide a linear arrangement of fluid/air passages in the spray gun  104 . 
         [0025]    It will be appreciated that the foregoing description provides examples of the disclosed system and process. However, it is contemplated that other implementations of the disclosure may differ in detail from the foregoing examples. All references to the disclosure or examples thereof are intended to reference the particular example being discussed at that point and are not intended to imply any limitation as to the scope of the disclosure more generally. All language of distinction and disparagement with respect to certain features is intended to indicate a lack of preference for those features, but not to exclude such from the scope of the disclosure entirely unless otherwise indicated. 
         [0026]    All references, including publications, patent applications, and patents, cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein. 
         [0027]    The use of the terms “a” and “an” and “the” and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms “comprising,” “having,” “including,” and “containing” are to be construed as open-ended terms (i.e., meaning “including, but not limited to,”) unless otherwise noted. 
         [0028]    Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention. 
         [0029]    Preferred embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. Variations of those preferred embodiments may become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors expect skilled artisans to employ such variations as appropriate, and the inventors intend for the invention to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.