Abstract:
A coating device comprises a longitudinal casing having an input end and an output end at opposed ends of a longitudinal direction, a coating liquid source, spray heads positioned inside the casing in a given arrangement and connected to the coating liquid source, so as to produce a spray of the coating liquid, and conveying means in association with the longitudinal casing so as displace an article along the longitudinal direction of the longitudinal casing such that the given arrangement of the spray heads enables to coat three faces of the article with the coating liquid. A method for coating an article is also provided.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]     The present patent application claims priority on United Kingdom Patent Application No. 0523137.8, filed on Nov. 12, 2005, by the present applicant.  
       BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to the general field of devices for applying coatings on articles and is particularly concerned with a portable coating device.  
         [0004]     2. Background Art  
         [0005]     There exists a plurality of situations wherein it is desirable to apply at least one layer of coating to an article in order to protect the latter and/or improve its aesthetical appearance. Various types of coatings including paint, lacquer, enamel, stains or the like are known. In the wood-related industries, staining remains a popular method of coating wood articles since it generally preserves the natural grain of the wood.  
         [0006]     Wood stain is applied to wood articles through different methods. When a relatively deep staining is required, allowing the stain to penetrate deeply into or even entirely through the wood article, the staining process is typically performed in an autoclave. The articles to be coated are placed in the autoclave and dipped into a colored stain. The autoclave is then closed and the penetrating staining is started by means of temperature and pressure increases, as is well known in the art. Depending on the type of wood and the thickness of wood article to be stained, penetrating staining can take several hours or even several days.  
         [0007]     When only the surface of the article needs to be stained, the staining process is typically performed either by painting or spraying or any other method known in the art. When the required staining needs to be performed at relatively high quality standards, it is common in the trade to use specialized professionals for performing the staining operation. The staining operation often requiring labor-intensive operations performed by specialized professionals can, hence, lead to relatively high staining costs.  
         [0008]     Indeed, during a typical staining process, the article being stained must be typically manipulated extensively while taking great care to avoid contacting already stained areas. This may prove particularly difficult in situations wherein the article being stained is a three-dimensional article having surface irregularities such as bent edges, indentations, curved surfaces, protrusions and the like.  
         [0009]     In order to circumvent the above-mentioned disadvantages, coating devices using spray heads for spraying fluent coating substances on articles as they are conveyed by a conveyor past the spray heads have been developed. Although at least partially alleviating some of the hereinabove-mentioned drawbacks, such conventional coating devices using conveyors shown in the prior art suffer from numerous drawbacks.  
         [0010]     One of these drawbacks relates to the fact that the spray heads are typically not adapted to provide a professional-looking coating finish. Indeed, the coating applied on the articles is often non-uniformly applied, deterring the overall aesthetical aspect of the object and potentially lessening the protection afforded by the coating to the article. This problem is further compounded in situations wherein the article being coated is a three-dimensional article presenting surface irregularities. One of the reasons for the increased difficulty in situations wherein three-dimensional articles having surface irregularities are being coated, is related to the fact that the spray heads are typically not adjustable. Hence, the angular orientation of the surface irregularities with respect to the direction of the spray typically varies. The more the surface varies from an orientation perpendicular to the spray direction, the more difficult it becomes to adequately coat the surface. Also, for curved or angled surfaces, difficulty in coating occurs in part because an angled or curved surface has a greater density of surface area than a flat surface. This means that, as the conveyor moves, the three-dimensional article passes the spray head, the surface area per unit time which passes the spray head is greater for angled or curved surfaces than for flat surfaces. Additionally, some surface irregularities are actually cut-out regions requiring no coating at all.  
         [0011]     Also, most conventional coating devices using conveyors only use spray heads and are not provided with suitable means for applying a distributing means such as a paint brush, a foam, a pad or the like on the sprayed surface so as to evenly distribute the coating material once sprayed thereon.  
         [0012]     Another drawback associated with conventional coating devices using conveyor for conveying articles past the spray heads relates to the fact that a considerable volume of coating material is often wasted. Indeed, most conventional prior-art coating devices using conveyors are not provided with suitable recycling or recovery means for recovering or recycling unused coating material dispended through the spray heads during operation.  
         [0013]     Furthermore, most conventional coating devices using conveyors are not well adapted to be easily cleaned between uses and are typically mechanically complex requiring intensive maintenance and frequent repair. Still furthermore, most conventional coating devices using conveyors are generally cumbersome and are not well adapted to be portable so as to be easily transported from one work site to another and conveniently stored when not in use.  
       SUMMARY OF INVENTION  
       [0014]     It is therefore a general object of the present invention to provide an improved coating device.  
         [0015]     Therefore, in accordance with the present invention, there is provided a coating device comprising: a longitudinal casing having an input end and an output end at opposed ends of a longitudinal direction; a coating liquid source; spray heads positioned inside the casing in a given arrangement and connected to the coating liquid source, so as to produce a spray of the coating liquid; and conveying means in association with the longitudinal casing so as displace an article along the longitudinal direction of the longitudinal casing such that the given arrangement of the spray heads enables to coat three faces of the article with the coating liquid.  
         [0016]     Further in accordance with the present invention, there is provided a method for coating an article by displacing the article in a casing, comprising the steps of: inletting an article in a casing; spraying a coating liquid onto there faces of the article; wiping excess coating liquid off the article; brushing coating liquid into the article; and outletting the article from the casing; whereby the article is coated. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0017]     An embodiment of the present invention will now be disclosed, by way of example, in reference to the following drawings, in which:  
         [0018]      FIG. 1A  is a partial longitudinal cross-sectional view with sections taken out, illustrating part of a coating device in accordance with an embodiment of the present invention;  
         [0019]      FIG. 1B  is a schematic longitudinal view of the coating device of  FIG. 1A ;  
         [0020]      FIG. 2  is a schematic partial longitudinal top cross-sectional view, illustrating part of the coating device shown in  FIG. 1 ;  
         [0021]      FIG. 3  is a partial perspective view with sections taken out, illustrating part of the adjustable spraying system incorporated in the device shown in  FIGS. 1 and 2 ;  
         [0022]      FIG. 4  is a partial perspective view with sections taken out, illustrating part of an adjustable brush-mounting assembly incorporated in the device shown in  FIGS. 1 and 2 ;  
         [0023]      FIG. 5  is a partial perspective view with sections taken out, illustrating part of a pad supporting component incorporated in the device shown in  FIGS. 1 and 2 ;  
         [0024]      FIG. 6  is a partial perspective view with sections taken out, illustrating part of an overhead pad supporting and tensioning component incorporated in the device shown in  FIGS. 1 and 2 ;  
         [0025]      FIG. 7  is a partial perspective view with sections taken out, illustrating part of a pad-mounting component;  
         [0026]      FIG. 8  is a partial perspective view with sections taken out, illustrating part of a brush-mounting component; and  
         [0027]      FIG. 9 , in a partial perspective view with sections taken out, illustrating part of a lateral pad-supporting component. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0028]     Referring to  FIG. 1  (i.e.,  FIGS. 1A and 1B ), there is shown in a longitudinal side cross-sectional view with sections taken out, part of a coating device  10  in accordance with an embodiment of the present invention. The device  10  typically has a generally elongated configuration defining a first or input end  12  and a generally opposed second or output end  14 . The device  10  includes a frame schematically illustrated, on which several components are mounted. The frame is preferably collapsible so as to minimize the required space for transportation and storage, and is preferably mounted on wheels, such as caster-type wheels or the like for facilitating transportation thereof.  
         [0029]     The device  10  typically includes an input platform  16  leading to a conveyor means  18  for allowing an intended user to manually, mechanically or otherwise feed articles to be coated to the device  10 . The conveyor means  18  may take any suitable form, such as a conventional belt-type conveyor or the like. A conveyor means  18  is intended to convey the articles through the device  10  to an outlet platform  20  wherein the articles once coated may be removed from the device  10  for further processing, storage or any other use. A shell component  22  is typically mounted over the frame of the device  10  so as to extend between the inlet and outlet platforms  16 , 20  in order to form a generally seal-type enclosure generally encompassing the frame of the device  10 . The output platform  20  may be optionally cushioned or otherwise modified to provide a suitable support for the coated articles. The shell component  22  is typically provided with a sealing lining  23  at strategic locations for maintaining a seal-type enclosure preventing fluent coating materials from flowing out of the device  10 . The device  10  is also preferably provided with sealing curtains  24  positioned adjacent to both the input and output apertures  26 ,  28  of the device  10  for maintaining a substantially seal-tight enclosure while allowing ingress and egress of the articles being coated into and out of the input and output apertures  26 ,  28 . The sealing curtains  24  are preferably made out of a generally flexible material such as a suitable elastomeric resin.  
         [0030]     The device  10  is also provided with a spray means for spraying articles with a coating material. The spray means typically includes a spray assembly  30  generally located adjacent to a top wall of the device  10  and adjacent to the input aperture  26 . As illustrated more specifically in  FIG. 3 , the spray assembly  30  typically includes both fixed spray heads  32  and adjustable spray heads  34  both attached to a spray head supporting beam  36 . The adjustable spray heads  34  are typically attached to slidable mounting frame  38  slidably mounted on the spray head mounting beam  36  for slidable movement therealong as indicated by arrows  40 ,  42 .  
         [0031]     Both the fixed and adjustable spray heads  32 ,  34  are typically hydraulically connected to a suitable pump  52  through suitable duct means including a fixed duct  44  anchored to the spray head supporting beam  36 . The pump  52  is, in turn, hydraulically coupled to a liquid container  54  typically mounted on top of the device  10 .  
         [0032]     The frame of the device  10  and a bottom wall  46  of the shell component  22  typically define a recuperation basin  48  for recuperating fluent liquid material within the device  10 . The basin  48  is typically provided with a drain  50  for facilitating maintenance thereof. The drain  50  is provided with suitable filtering screens for filtering out unwanted particles and allowing at least part of the recuperated liquid within the basin  48  to be recycled towards the spray heads  32 , 34  through the use of the pump  52 . Both the spray heads  32  and  34  are typically provided with spray adjustment means for adjusting the pattern of the spray emanating therefrom.  
         [0033]     The coating device  10  is typically further provided with at least one and preferably two coating-applying brushes  56  having suitable brush bristles  58  extending from a brush head  60 . The brush  56  is typically mounted to a top wall  62  of the device  10  using a brush-mounting component  64 . The brush-mounting component  64  includes generally L-shaped retaining flanges  66  extending therefrom for slidably receiving the brush head  60 . The brush component  56  may be sectioned so as to allow adjustment of the length of the brush component  56  depending on the configuration and size of the article being coated.  
         [0034]     As shown more specifically in  FIG. 7 , wiping pads  68 , a wiping component  70  mounted to a pad head  72 . The wiping pads  68  are typically attachable to pad-supporting components  74  having generally L-shaped pad-supporting flanges  78  by slidable engagement therewith, as indicated by arrow  76 .  
         [0035]     Again, the wiping pads  68  may be segmented so as to allow for adjustment of the length of the wiping area depending on the configuration and size of the article being coated. When relatively small articles are being coated, the length of both the brushes and pads may be shortened by using only a section thereof. In such situations, guiding walls  80  positioned adjacent to the inlet platform  16  allow for proper positioning and centering of the smaller articles.  
         [0036]     Wiping pads  78  may also be mounted within the device  10  so as to wipe the lateral surfaces of articles.  FIG. 9  illustrates a lateral pad-supporting assembly  82  for positioning wiping pads, such as wiping pads  68 , in a lateral relationship relative to articles being conveyed on the conveying means. The assembly  82  includes a supporting post  84  having arms  86  extending downwardly therefrom. Mounting brackets  88  including L-shaped flanges  90  are hingedly mounted to the arms  86  by hinge components  92 . The L-shaped flanges  90  are configured and sized for slidably receiving the wipe pad heads  72 , such as shown in  FIG. 7 . As the articles are conveyed by the conveyor means, the articles push on the wiping pads  68  hence pivoting the panels  88  according to arrows  94 . Biasing means such as springs are provided for biasing the panels or brackets  88  back towards their initial position, wherein they lie in a generally parallel relationship relative to the supporting rod  84 .  
         [0037]      FIG. 5  illustrates a mounting assembly  96  for mounting wiping pads  68  in an overlying relationship relative to the articles being coated. The assembly  96  includes a supporting rod  98  and a mounting bracket  100  hingedly mounted thereto by hinge components  110 . Similarly, the mounting bracket  100  is provided with L-shaped flanges  112  for slidably receiving wipe pad heads  72 . The hinge components  110  are provided with biasing means for biasing the latter towards the initial configuration wherein they lie in a generally perpendicular relationship relative to the support beams  98 .  
         [0038]     As illustrated in  FIG. 6 , wiping pads  68  may also be mounted to a tensioned mounting assembly  114 . The tensioned mounting assembly  114  pivotally includes first and second mounting brackets  116 ,  118  having L-shaped flanges  120  for slidably receiving pad heads  72 . The mounting brackets  116 ,  118  are respectively attached to a first and second arm  122 ,  124  part of generally L-shaped and spaced-apart mounting legs  126 . The mounting legs  126  are provided with biasing means such as helicoidal-type springs  128  attached thereto for biasing mounting legs  126  towards an initial configuration wherein the arms  122  extend in a generally horizontal configuration. The arms  124  are pivotally mounted to the walls of the device  10  for pivotal movement relative thereto. It should be understood that the mounting brackets shown throughout the figures may receive either wiping pads or brushes  68 ,  56  and that the latter may be interchanged within the device  10  without departing from the scope of the present invention. In other words, various combinations of wiping pads and brushes  68 ,  56  forming different configurations may be used without departing from the scope of the present invention.  
         [0039]     The height of the supporting assembly relative to the conveying means may be adjusted depending on the configuration and size of the article being coated. For example, the supporting beams  64 ,  74 ,  84  and  98  may be mounted at longitudinal ends thereof into apertures  130  and recesses  132  formed at different heights within corresponding supporting panels  134 ,  136  located on each lateral side of the device  10  therealong.  
         [0040]     Operation of the device  10  may be accomplished either manually or automatically using suitable control means including a control panel  138  located outside the device  10 .  
         [0041]     The coating device  10  allows for the application of fluent coating material of various sorts on various types of three-dimensional objects. The coating device  10  allows for a generally constant and uniformed coating to be performed on various objects even when the latter present a certain degree of surface irregularities.  
         [0042]     Also, the coating device  10  allows coating to be applied to various types of articles while reducing the required manipulation of such articles through a set of quick and ergonomic steps without requiring skilled or trained work persons.  
         [0043]     Furthermore, the coating device  10  is designed so as to reduce the wastage of coating material and allow recycling of at least a portion of the unused coating material dispensed during operation of the device. Also, the device  10  is designed so as to be easily cleaned, serviced and repaired. Still furthermore, the device  10  is designed so as to be generally reliable, long-lasting and cost-efficient.