Abstract:
An in-line parts washing system comprising concatenated modules of two discrete lengths where certain of the modules have a self-contained tank of parts cleaning chemical along with a motor-driven pump for forcing the cleaning chemical through spray heads enclosed in a shroud through which the parts to be cleaned are transported via a conveyor. Other modules disposed in-line with the wash modules provide zones where the cleaning chemical dripping from the parts is collected and redirected back into the tanks from which it originated. The ability to swap modules of differing length allows a user to easily alter the cleaning process.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    I. Field of the Invention 
         [0002]    This invention relates generally to apparatus for industrial pre-cleaning of machine parts prior to painting or powder coating of such parts, and more particularly to a multi-stage, in-line washer whereby parts to be cleaned are subjected to a pressurized spray at elevated temperatures of chemical cleaning solutions for predetermined time periods determined by the number of stages employed. 
         [0003]    II. Discussion of the Prior Art 
         [0004]    As explained in the Pascaru U.S. Pat. No. 5,257,739, machined parts must be chemically cleaned to remove oils and other residues therefrom before painting or powder coating operations can be performed on these parts. Spraying equipment used to clean, rinse and otherwise treat articles of manufacture take place in a confined area, such as a spray or washer booth, in which various liquids are piped under pressure through headers into a plurality of vertical pipes, called risers, that connect to the headers and then out through nozzles attached to the risers and which are adapted to forcefully spray work pieces as they pass through the washer booth being transported by an overhead conveyor or other suitable transport mechanism. 
         [0005]    As further explained, prior art washer booths are customarily made of steel and are equipped with a pair of header pipes that are spaced apart and that run parallel and longitudinal to the floor or ceiling of the washer booth. Industrial liquids are stored in a tank beneath the washer booth floor and are pumped through suitable plumbing to the headers. A bank of plastic or steel risers is connected to each header and extends upward or downward along an adjacent wall of the washer booth depending on the header&#39;s placement. Parts to be treated may be carried through the booth and exposed to chemical spray by a suitable conveyor. 
         [0006]    Pretreatment systems have four major process requirements needed to affect suitable parts cleaning. They are:
       Temperature of the bath;   Concentration of the chemistry in the bath;   Pressure of the liquid spray on the part (impingement);   Time in each wash stage.       
 
         [0011]    The concentration, pressure and temperature are capable of adjustment once the washer is built, but after a washer has been built; the exposure time is fixed, based on the length dimension of the washer and each of its stages. 
         [0012]    For example, assume a company has designed to run a conveyor of the parts to be cleaned at 4 feet per minute and that three process stages are required. Three process stages typically require two drip zones, one entrance and one exit vestibule with a 1 minute soak time required in each stage. Under these assumptions, a wash booth would have to be 28 feet in length. Over time, should the company decide to increase the conveyor speed to add throughput, it would have to sacrifice soak time or, alternatively, add length to the washer, usually at considerable expense. Also, if the company needs to add another stage to improve its process or possibly add another type of process, it will not be able to do that without substantial added cost. In the case of the prior art, it is a major project to add length to a washer or to shorten it. 
         [0013]    Existing washers of which we are aware typically occupy a significant amount of factory floor space and are inefficient in terms of energy needed to pump and heat the liquid cleaning agents. 
         [0014]    Those skilled in the art, then, can appreciate that a need exists for an in-line pretreatment system that is modular in design, allowing stages to be easily added or removed based upon customer requirements. 
         [0015]    Another problem with prior art parts washer booths is that they do not permit easy access to the piping system comprising the nozzles, risers and headers contained within the booth so that adjustments may be made to the direction and spray pattern employed. Thus, a need exists for an in-line pretreatment system that allows easy access to interior components for cleaning, adjustment repair and replacement. 
         [0016]    Another drawback of prior art washers is that they need some type of filtration system in the first wash stage to help keep the bath clean so as to offer an extended bath life. The filtration systems commonly employed require an additional pump and bag filtration system typically placed adjacent to the washer. Such filtration systems therefore require additional energy and floor space. A need therefore exists for a more compact and energy efficient way for filtering the wash chemicals. 
         [0017]    It is therefore a principal object of the present invention to provide an in-line pretreatment system for washing machine parts that solves the aforementioned problems attendant in known prior art systems by providing a modular configuration of different length stages that can be concatenated to vary the time of exposure and the types of chemicals needed for the cleaning process at hand. The modules have been specifically designed to provide greater flexibility and ease of access to interior components while also reducing the overall footprint and energy consumption needed to operate the system. 
       SUMMARY OF THE INVENTION 
       [0018]    A pre-washer assembly for use with an overhead conveyor that is adapted to carry machine parts through the pre-washer assembly for cleaning prior to their being painted or powder coated comprises a plurality of concatenated wash stages where each wash stage includes a base frame assembly having a motor-driven pump mounted thereon and also supporting a generally rectangular tank. The tank itself has opposed sidewalls and end walls that extend upward from a closed bottom wall to define an open top. The tank is adapted to hold a cleaning liquid supply therein. First and second upright assemblies are attached individually to the opposed sidewalls of the tank and each of the upright assemblies includes a plurality of inverted, L-shaped uprights that are held in parallel, spaced-apart relation by horizontally extending cross-members. The upper legs of the uprights affixed to the opposed sidewalls of the tank extend toward one another but with a gap between opposed ends of the inverted L-shaped uprights. First and second roll formed plastic shrouds removably attach to the first and second upright assemblies, forming a cabinet-like structure partially surrounding horizontally extending headers and upwardly extending riser pipes to which plural spray nozzles are joined. A motor-driven pump, preferably a centrifugal pump, is arranged to draw the cleaning liquid from the tank and supply it via the headers to the risers and nozzles. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0019]    The foregoing features, objects and advantages of the invention will become apparent to those skilled in the art from the following detailed description of a preferred embodiment, especially when considered in conjunction with the accompanying drawings in which like numerals in the several views refer to corresponding parts. 
           [0020]      FIG. 1  is a perspective view of a preferred embodiment of the present invention; 
           [0021]      FIG. 2  is a perspective view of one washer stage of the multi-stage embodiment of  FIG. 1 ; 
           [0022]      FIG. 3  is a perspective view of the base frame assembly used in implementing the module of  FIG. 2 ; 
           [0023]      FIG. 4  is a perspective view of a tank used in the embodiment of  FIG. 2 ; 
           [0024]      FIG. 5  is a perspective view of a welded upright assembly used in the fabrication of the module of  FIG. 2 ; 
           [0025]      FIG. 5A  is a perspective view of a drip edge assembly for the tank of  FIG. 4 ; 
           [0026]      FIG. 6  is a perspective view of a spray cabinet shroud; 
           [0027]      FIG. 7  is a perspective view of a tray assembly used in implementing a drip module used in the assembly of  FIG. 1 ; 
           [0028]      FIG. 7A  is a perspective view of a short drip tray assembly; 
           [0029]      FIG. 8  is a perspective view of a shroud for a drip module component of the embodiment of  FIG. 1 ; 
           [0030]      FIG. 8A  is a perspective view of a shroud used with the short drip tray assembly of  FIG. 7A ; 
           [0031]      FIG. 9  is a perspective view of a filter tray used in the embodiment of the module of  FIG. 2 ; and 
           [0032]      FIG. 10  is a filter tray support assembly used in implementing the wash module of  FIG. 2 . 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0033]    This description of the preferred embodiments is intended to be read in connection with the accompanying drawings, which are to be considered part of the entire written description of this invention. In the description, relative terms such as “lower”, “upper”, “horizontal”, “vertical”, “above”, “below”, “up”, “down”, “top” and “bottom” as well as derivatives thereof (e.g., “horizontally”, “downwardly”, “upwardly”, etc.) should be construed to refer to the orientation as then described or as shown in the drawings under discussion. These relative terms are for convenience of description and do not require that the apparatus be constructed or operated in a particular orientation. Terms such as “connected”, “connecting”, “attached”, “attaching”, “join” and “joining” are used interchangeably and refer to one structure or surface being secured to another structure or surface or integrally fabricated in one piece, unless expressively described otherwise. 
         [0034]    Referring first to  FIG. 1 , there is indicated generally by numeral  10  the configuration of an in-line pretreatment system for cleaning machine parts constructed in accordance with a first embodiment of the present invention. It is seen to comprise a plurality of concatenated wash stages or modules  12 ,  14  and  16  with intermediate drip modules  18  and  20 . Product to be cleaned is made to enter the pretreatment system of  FIG. 1  via an entry stage  22  and to leave via the exit stage  24 . Each of the identified modules is constructed so as to have a longitudinally extending gap centrally located in a top portion of each module. The assembly of  FIG. 1  is adapted to be positioned directly below an overhead chain conveyor from which parts to be cleaned are suspended from chain linkages that extend vertically through the gaps  26 . The size of the part or the rack on which plural parts may be mounted is limited only by the height and width dimension of the modules and the placement of riser pipes there within. 
         [0035]    Without limitation, the wash stages or modules  12 ,  14  and  16  may be produced in two sizes, i.e., they may have an overall length dimension of about 4 feet or 6 feet. Likewise, the drip modules  18  and  20  may also be made in both 4 feet and 6 feet lengths. The entry module  22  and the exit module  24  will typically be 4 feet in length. By providing washer modules in 4 foot or 6 foot increments, stages can be assembled to equal 4, 6, 8, 10 and 12 foot zones. The entrance and exit modules  22  and  24  and the drip zones  18  and  20  serve to contain the spray and keep the cleaning liquid in the proper stages as the parts are carried through the washer by the overhead conveyor (not shown). As will be further explained, when two wash stages are to be joined to one another in directly adjacent relation, a narrow drip stage is used to collect overspray or splash and return it to the tank of a wash stage. 
         [0036]      FIG. 2  is a perspective view of one of the wash stages used in the embodiment of  FIG. 1 . It is seen to comprise a base frame assembly  28 , the constructional features of which are best seen in the perspective view of  FIG. 3 . The base frame assembly  28  is preferably formed from 1 in.×1 in. 11-gauge stainless steel tubing and includes left and right side rails  30  and  32  that are held in parallel, spaced-apart relation by a plurality of transversely extending cross rails  34 ,  36 ,  38 ,  40 ,  42  and  44 . Projecting up from the side rails  30  and  32  are posts  46  and  48 . Like posts  50  and  52  also project upward from the side rails  30  and  32  at their juncture with the ends of the cross bar  40 . A pair of shorter side rails  54  and  56  is welded in place between the upper ends of the posts  46 ,  50  and  48 ,  52  as illustrated. An upper cross bar  58  also extends between the upper ends of the posts  46  and  48 . 
         [0037]    As seen in  FIG. 2 , a tank  60  is designed to drop into the base frame assembly  28 . Details of the tank  60  are illustrated in the perspective view of  FIG. 4 . The tank  60  is preferably fabricated from ½ in. thick copoly elastomer which exhibits high impact strength, some flexibility and resistance to chemical attack from cleaning liquids employed. With a base frame  28  designed for use in a 6 ft. long washer module, the tank may measure 73 in. by 37 in. allowing it to hold approximately 180 gallons of liquid. Similarly, for a washer module of 4 ft. length, the tank may be 49 in. long and 37 in. wide and will hold approximately 120 gallons of cleaning liquid. 
         [0038]    As seen in  FIG. 4 , the tank  60  has a bottom or floor  62  with mutually perpendicular sidewall  64  and  66  and end walls  68  and  70 . While not visible in the view of  FIG. 4 , the bottom surface  62  is made to slope downward in extending from the end wall  68  to the front wall  70 . Formed through the front wall  70  is a plurality of apertures, allowing plumbing connections to be made between the tank interior and the inlet to a motor-driven pump  71 , preferably a centrifugal pump, seen in  FIG. 2 . Plumbing connections are also made from the pump&#39;s outlet port through apertures in the wall  70  to manifolds  73 , called headers, also visible in  FIG. 2 , that extend along the module&#39;s two opposed sidewalls. Projecting vertically upward from the pair of headers and in fluid communication therewith are a plurality of parallel, spaced-apart riser tubes  75  on which nozzles, as at  77 , are disposed for producing jets of cleaning solution drawn from the tank at pressures in a range of 5-30 psi and onto parts to be cleaned that are being conveyed through the wash stage  16 . 
         [0039]    Other apertures are formed through the front wall of the tank to accommodate electrical controls  79  leading to immersible heater modules  81  disposed within the tank  60  for controlling the temperature of the cleaning liquid. Alternatively, an external gas heater and pump may be used to feed heated cleaning elements to the tank. Also, a drain aperture is provided in which a gate valve  83  is placed to allow dirty fluid to be periodically drained from the tank. Enclosure  85  contains control circuitry for the pump motor  87 . 
         [0040]    Chemically welded or otherwise bonded to the opposed sidewalls  64  and  66  of the tank are upright assemblies  72 , a portion of which can be seen in  FIG. 2 . The perspective view of  FIG. 5  shows one of the upright assemblies before its being affixed to the tank side wall. As seen in  FIG. 5 , the upright assembly  72  comprises a plurality of inverted L-shaped uprights, as at  74 , held in parallel, spaced-apart relation by cross members  76  and  78 . The upright assemblies  72  are also preferably formed from ¾ in. thick copoly elastomer and when a pair of these assemblies  72  are welded to the side walls of the tank  60 , the upper legs, as at  80 , extend toward one another across the width dimension of the tank while leaving a gap  26  ( FIG. 2 ) between the ends of the upper legs  80  on the pair of upright assemblies. 
         [0041]    The upright assemblies  72  are designed to support first and second spray shrouds  82  and  84 . The bottom edge of each of the shroud members  82 ,  84  is suspended over a drip edge member  86  that rests upon the upper portion of the tank  60  and that has a flange extending over the peripheral edges of the tank  60  such that sprayed liquid running down the inside walls of the spray shrouds  82  and  84  will flow onto the drip edge member  86  and flow back into the tank  60 . 
         [0042]      FIG. 5A  is a perspective view of the drip edge member. It is a welded steel assembly whose sides  87  and  89  and opposed ends  91  and  93  form a rectangular frame having a horizontally extending offset  95  with a perpendicular flange  97  projecting downward therefrom and dimensioned to closely fit to the inner wall surface of the tank  60 . Projecting upward from the offset  95  is a wall surface  99  that surrounds the bottom edge portion of the shroud. 
         [0043]    Referring next to  FIG. 6 , there is a perspective view of one of the spray shroud members  82 ,  84 . It is seen to comprise a generally planar sheet of ¼ in. thick copoly elastomer extending from a bottom edge  86  to an upper edge  88  where it mates with a curved wrap  90  creating a 90° bend and terminating at an outer edge  92 . A pair of handles  94  are bolted to the shroud as shown to facilitate lifting and carrying thereof. Also chemically welded to the horizontally extending portion of the shroud proximate the outer edge  92  are L-shaped brackets  96  on either side edge thereof. The brackets  96  provide a way whereby shroud panels on adjacent modules can be releasably joined to one another as illustrated in the view of  FIG. 1 . 
         [0044]    The drip stages  18  and  20  shown in the in-line pretreatment system of  FIG. 1  have a somewhat different construction than the spray stages  12 ,  14  and  16 . They basically comprise a drip tray assembly that hooks onto the tanks of adjacent ones of the spray modules and that supports a panel having a convex curvature such that liquids dripping from the work pieces traversing the drip module and falling onto the panel will flow downhill into one or the other of two adjacent spray stages. 
         [0045]      FIG. 7  is a perspective view of a drip tray assembly for a 4 ft. long drip stage  18 . It is seen to comprise a left side member  102 , a right side member  104  and a tray surface  106 . The left and right tray sides  102  and  104  are held in parallel spaced-apart relationship by a plurality of cross braces as at  108 . The sides members  102  and  104  may be fabricated from ¾ in. copoly elastomer while the cross pieces  108  may be ½ in. in thickness. The tray surface  106  may then comprise a sheet of copoly of ¼ in. thickness whereby it can be made to flex to conform to a convex curve of grooves formed inwardly along the length dimension of the left and right side members  102 ,  104 . The convex curved sheet  106  is held in place by a plurality of standoff blocks as at  110 . The stand-off blocks also serve to seat the shrouds in place on the drip modules. 
         [0046]    With continued reference to  FIG. 7 , it will be seen that the left and right side members are provided with slots  112  proximate the opposed ends thereof allowing the side members  102  and  104  to fit onto the walls  99  of the drip edge member  86  of adjacent wash modules. The thickness of the side members  102  and  104  is such that they are able to support drip shrouds  114  thereon. 
         [0047]      FIG. 7A  is a perspective view of a short drip tray assembly that is used when it is desired to join two wash modules, like that shown in  FIG. 2 , one to the other. It is designed to capture overspray and route liquid falling thereon back into the tank of the wash module with which it is coupled. It comprises side members  101  and  103  joined to one another by a cross brace  105  and supporting a sheet  107  of impervious plastic. As can be seen in  FIG. 7A , the sheet  102  is inclined to the vertical supported on its opposed end edges by an angled shelf surface formed on the side members  101  and  103 . Standoff blocks  109  are also provided on the short drip tray of  FIG. 7A . 
         [0048]    Like the long drip tray of  FIG. 7 , the right and left end members  101  and  103  have tabs defined by slots as at  111  whereby the short drip tray can be clipped onto the vertical walls of adjacent drip edge assemblies that mount to the tanks of the adjacent wash modules. 
         [0049]      FIG. 8  is a perspective view from the rear of a drip shroud  114 . It is preferably fabricated from a rectangular sheet of copoly elastomer  116  having chemically welded or bonded thereto a wrap  118 . Affixed to the opposed side edges of the sheet  116  and the wrap  118  are inverted, L-shaped side panels  120  and  122 . A strip  124  of copoly elastomer extends from the upper end of the side member  120  to the upper end of the side member  122  and is chemically welded in place. Also affixed to the inner surface of the copoly sheet  116  are flow diverters as at  126 . They are mounted with a downward slant insuring that water dripping therefrom will flow onto the convex surface  106  of the tray member  100  and from there to adjoining tanks of adjacent modules. 
         [0050]    The drip shroud  114  also includes a pair of spaced apart, vertically oriented handles  128  that are shown in phantom line in  FIG. 8 . 
         [0051]      FIG. 8A  is a perspective view of a short drip shroud designed for use with the short drip tray of  FIG. 7A . Except for its width dimension, it is substantially identical in its construction to the drip shroud of  FIG. 8  and a further description of it is deemed unnecessary. 
         [0052]    The wash module of  FIG. 2  also illustrates the incorporation of a tray mounted filter  130  disposed above the tank  60  and arranged to trap solids which may fall from work pieces as they are being spray cleaned.  FIG. 9  is a perspective view of the filter tray assembly  130 . It comprises a ½ in. thick copoly elastomer frame including long side pieces  132  and  134  and short side pieces  136  and  138  along with a center brace  140 . The side members  132 - 138  join together to form a rectangular frame on which is mounted a perforated sheet or screen  142 . The filter tray  130  provides support for a suitable filter media such as a length of polypropylene batting capable of removing oily residue from the cleaning liquid as the contaminated spray passes through the filter media and the perforations of the supporting sheet  142  of the frame  130 . 
         [0053]    The filter tray  130  is adapted to be supported by the structure  144  shown in  FIG. 10 . This structure is dimensioned to fit within the tank  60  and is fabricated from ¾ in. thick copoly components that are chemically welded or otherwise bonded to form the structure illustrated. It includes left and right side members  146  and  148  having a center section which may be approximately 6 in. in height and spanning approximately 27 in. in length when adapted to fit within the tank designed for a 4 ft. long wash module. The sides then curve upwards to a substantially narrower width proximate its opposed ends. The side members  146  and  148  are held apart by cross members  150  and  152  of equal length and extending between those two cross members is a center support member  154 . Further cross supports  156  and  158  extend between the narrow end portions of the side members  146  and  148 . 
         [0054]    The filter tray support  144 , when placed within the tank, allows the filter tray of  FIG. 9  to rest upon the upper edges of the sidewalls  146  and  148 , the cross members  150  and  152  and the center support member  154 . Because of the manner in which the filter tray is suspended, it can be readily removed by simply sliding the tray along the upper surface of the tray support of  FIG. 10  to a location where an operator may readily remove a dirty filter media and replace it with a fresh sheet thereof. 
         [0055]    From what has been described, those skilled in the art will recognize that the present invention offers part finishers and environmentally friendly product that combines never before seen flexibility of high volume throughput with low capitol outlays and operating costs along with the ability to react to constantly changing production demands and that is capable of utilizing present day low temperature chemistries. As processes change, the in-line pretreatment system of the present invention can easily be adapted to meet customer demands. It has been shown how wash and drip modules can be easily added or removed to change the exposure time of treatment. Likewise, chemistries can easily and quickly be changed by draining a tank of a first chemistry and replacing it with another. Due to the small capacity of the tanks employed, there is less concern of exceeding local wastewater discharge permit levels. Also, the small footprint of the apparatus makes an in-line cleaning process possible in facilities where space is at a premium and known prior art devices are unable to be used because of space limitations. 
         [0056]    This invention has been described herein in considerable detail in order to comply with the patent statutes and to provide those skilled in the art with the information needed to apply the novel principles and to construct and use such specialized components as are required. However, it is to be understood that the invention can be carried out by specifically different equipment and devices, and that various modifications, both as to the equipment and operating procedures, can be accomplished without departing from the scope of the invention itself.