Abstract:
An apparatus and method for applying a blasting media, comprised of at least first and second separate types of particles, to a surface to be treated. Each type of particle may comprise a core coated with a desired component, e.g. abrasive, absorptive, polishing, etc., and the components are selected so as to minimize the density variation of different types of media being combined with one another for the surface treatment. The different types of particles are mixed with one another prior to application to a surface to be treated. The mixing may occur in a mixing tank prior to use, in the media supply conduit prior to the nozzle, at the discharge outlet of the nozzle, or just prior to contacting the surface to be treated. By employing different types of particles, cleaning and reuse of the media is facilitated while also minimizing the amount of media consumed per unit area of wall to be treated. In addition, an operator is able to custom blend the media, during use at a jobsite, to maximize surface treatment, per pound of media, and minimize the generation of disposable waste.

Description:
FIELD OF THE INVENTION  
       [0001]     This invention relates to an improved blasting media, and more particularly to a blasting media comprised of a desired blend of two or more separate types of particles, e.g abrasive, absorptive, carrier, polishing, other surface finishing or treating particles and/or combinations thereof.  
       BACKGROUND OF THE INVENTION  
       [0002]     It is known in the art to apply various substances and materials to a desired surface and to remove contaminants, rust, debris, paint, etc., from a surface by the use of blasting media. The blasting media may consist of a dry or a liquid material or a substantially uniform combination thereof formed as individual unitary particles.  
         [0003]     Traditionally during a blasting operation, the media is mixed by using various sized particles of the same kind or type of media, i.e. all of the media particles generally have the same composition. Some blasting media known in the art attempt to combine abrasive components and absorptive components, for example, in the same particle. The resulting particles must be absorptive enough to remove liquids and control dust while, at the same time, be aggressive enough to remove contaminants and debris, e.g. rust, paint, oil, etc., which has adhered to the surface from which it is to be removed.  
         [0004]     Using a single kind or type of particle with abrasive and absorptive components incorporated therein leads to the problem of recontamination of the surface being treated once the media absorbs a significant amount of contaminants and is re-used. Another problem is that the abrasive and absorptive properties of the particles are compromised by combining the components&#39; functions in a single particle. In addition, such combination does not allow an operator to customize the media, during use, to take into consideration variations in the amount of contaminants and debris contained on a particular area of the surface to be cleaned and may lead to excessive consumption of the media, e.g. if the media does not contain a great enough abrasive content for the particular surface to be cleaned or a great enough absorptive content, additional media is required to ensure adequate surface treatment.  
       SUMMARY OF THE INVENTION  
       [0005]     Wherefore, it is an object of the present invention to overcome the aforementioned problems and drawbacks associated with the prior art designs.  
         [0006]     Another object of the invention is to provide a blasting media having a first type or kind of particles and at least a separate second type or kind of particles which are combined with one another prior to impacting against a surface to be treated.  
         [0007]     Yet another object is to provide a system which provides easy separation of the various used blasted particles from one another for cleaning, disposal, recycling, reuse, etc.  
         [0008]     Still another object is to employ abrasive particles and absorptive particles, for example, which each have approximately the same weight for particles of about the same size.  
         [0009]     Another object is to provide a surface treatment system which facilitates cleaning and reuse of at least the absorptive particles.  
         [0010]     A further object of the invention is to provide a surface treatment system which allows custom blending of the media, at a jobsite, to facilitate maximum surface treatment while consuming a minimum amount of blasting media during use.  
         [0011]     The present invention relates to a blasting media system comprises at least first and second types of different blasting particles, said system comprising: a) a first container containing a supply of at least said first type of blasting particles; b) a first supply conduit having a first end and a second end, said second end facilitating discharge of at least said first type of blasting particles against a surface to be treated for providing the desired surface treatment thereof; c) a first metering device for metering at least said first type of blasting particles from said container into said first end of said supply conduit; and d) a first device for pressurizing said first end of said supply conduit with a pressurized fluid whereby said pressurized fluid and at least said first type of blasting particles mix with one another in said supply conduit to form a pressurized mixture thereof; wherein said second type of blasting particles is mixed with said first type of blasting particles and said pressurized fluid, prior to the first and second particles contacting the surface to be treated, whereby the first and second mixed particles comprise two separate types of blasting particles which facilitates the desired surface treatment of the surface to be treated and reuse of the media.  
         [0012]     The present invention also relates to a method of supplying blasting media comprising at least first and second types of different blasting particles to a surface to be treated, said method comprising the steps of: a) containing a supply of at least said first type of blasting particles in a first container; b) providing a first supply conduit with a first end and a second end, said second end facilitating discharge of at least said first type of blasting particles against a surface to be treated for providing the desired surface treatment thereof; c) metering, via a first metering device, at least said first type of blasting particles from said container into said first end of said supply conduit; and d) pressurizing, via a first pressurizing device, said first end of said supply conduit with a pressurized fluid whereby said pressurized fluid and at least said first type of blasting particles mix with one another in said supply conduit to form a pressurized mixture thereof; e) mixing said second type of blasting particles with said first type of blasting particles and said pressurized fluid prior to the first and second types of particles contacting the surface to be treated, whereby the mixed particles comprise two separate types of blasting particles which facilitates the desired surface treatment of the surface to be treated and reuse of the media. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]     The invention will now be described, by way of example, with reference to the accompanying drawings in which:  
         [0014]      FIG. 1  is a diagrammatic elevational view of a blasting media applicator according to the present invention;  
         [0015]      FIG. 2  is a diagrammatic elevational view of a second embodiment of the blasting media applicator according to the present invention;  
         [0016]      FIGS. 3A and 3B  are diagrammatic cross-sectional views of second variations of the blasting particles according to  FIG. 1 ;  
         [0017]      FIGS. 4A and 4B  are diagrammatic cross-sectional views of third variations of the blasting particles according to  FIG. 1 ;  
         [0018]      FIG. 5  is a diagrammatic elevational view of a third embodiment of the blasting media applicator according to the present invention;  
         [0019]      FIG. 6A  is a diagrammatic end view of a second embodiment of a blasting nozzle;  
         [0020]      FIG. 6B  is a diagrammatic cross-sectional view of the nozzle according to  FIG. 6A ; and  
         [0021]      FIG. 7  is a diagrammatic elevational view of a fourth embodiment of the blasting media applicator according to the present invention showing a containment barrier and a surface to be treated in cross section.  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0022]     Turning now to  FIG. 1 , a detailed description concerning the present invention will now be provided. Blasting media applicator, generally designated by reference numeral  1 , comprises a tank  2 . Mixer or auger  4  is rotatably attached at a first end thereof to motor  6 , supported (not shown in detail) above tank  2 . Auger  4  is suspended within tank  2  for agitation of the media. Power cable  8  is connected at a first end thereof to motor  6  and at its opposite end to an appropriate power source  10 , such as an AC outlet or battery.  
         [0023]     Abrasive particles  12  and absorptive particles  14  contained within tank  2  typically have different densities, which leads to separation of the two different types of particles  12 ,  14  in the blasting equipment during use, i.e. the heavier abrasive particles  12  generally sink toward the bottom of the container while the lighter absorptive particles  14  generally rise toward the top of the container. The mixing action of auger  4  located within tank  2 , when motor  6  is operating, completely and uniformly mixes the abrasive particles  12  with the absorptive particles  14 , thereby preventing separation of the two components from one another and assists with achieving a substantially uniform supply of blasting media to the surface to be treated. Virtually any known mixing device may be employed as long as it is able to uniformly mix the particles  12 ,  14  in tank  2 . As such feature is well known to those skilled in this art, a further detailed description concerning the same is not provided herein.  
         [0024]     The media  11  to be discharged comprises a desired blend of abrasive particles  12  and absorptive particles  14  supplied by tank  2 . Abrasive particles  12  may be any one of a variety of known abrasive components, such as corn, plastic, Black Beauty®, black walnut shell grit, sand, garnet or other available abrasive grits, etc., depending upon the application.  
         [0025]     Blasting device  20  (designated by the dashed line) comprises tank  2 , supply conduit  16 , a pressurized air supply source  18 , and a conventional metering device or means  19 . Supply conduit  16  is connected at a first end thereof to the pressurized air supply source  18  and at a second end thereof to a blasting nozzle  22 . Metering device or means  19  is connected at a first end thereof to tank  2  and at a second end thereof to a “tee” provided in the first end of supply conduit  16 . Metering device or means  19  may be an auger or any other known positive feed device which will feed and/or meter a desire flow rate of media  11  from tank  2  into air supply conduit  16 .  
         [0026]     Air supply source  18  provides a stream of pressurized air, e.g. typically at a pressure ranging from about 2 psi to about 100 psi, into supply conduit  16 , and media  11 , comprising a desired blend of the surface treatment particles, e.g., approximately equal amounts of abrasive particles  12  and absorptive particles  14 , is supplied via metering means  19  into supply conduit  16  and conveyed to blasting nozzle  22 . Blasting nozzle  22  directs the supplied stream  26 , including air and media  11 , at a desired surface S to be treated.  
         [0027]     A second embodiment of the present invention is shown in  FIG. 2 . Blasting device  20 ′ (designated by the dashed line) comprises supply conduit  16 , connected at a first end thereof to a pressurized air supply source  18  and at a second end thereof to a blasting nozzle  22 . Metering means  19  is connected at a first end thereof to tank  2 , which is a closed container in this embodiment, and at a second end thereof to a “tee” provided in the first end of supply conduit  16 . A second pressurizing conduit  17  is connected at a first end thereof to air supply source  18  and at a second end thereof to tank  2  for pressurizing the tank  2  to the same pressure as the remainder of the system.  
         [0028]     The air pressure within tank  2 , in combination with metering means  19 , conveys the mixed and combined media  11  into the pressurized air stream contained within supply conduit  16 . The pressurized air conveys media  11  through supply conduit  16  and out through blasting nozzle  22  as stream  26  which is direct toward a surface S to be treated.  
         [0029]     It is to be appreciated that metering means  19  may be a variety of different devices, depending upon the application. In the first embodiment, as depicted in  FIG. 1 , tank  2  is at atmospheric pressure and supply conduit  16  is under a higher pressure due to air supply source  18 . Metering means  19 , therefore, must be a feeding device which will overcome the pressure in supply conduit  16  and still accurate and positively meter or feed media  11  from tank  2  into supply conduit  16  at a desired flow rate, e.g. linear flow rate. In the second embodiment, as depicted in  FIG. 2 , as tank  2  and supply conduit  16  are both pressurized substantially equally, metering means  19  may be a somewhat simplified feed device, such as a screw conveyor or an auger, which will feed media  11  in at a desired flow rate, e.g. linear flow rate, into supply conduit  16 .  
         [0030]     According to a second embodiment of media  11 , as shown in  FIGS. 3A and 3B , abrasive particle  12  ( FIG. 3A ), for example, comprises a central core  28  surrounded or encapsulated by an abrasive component  30 , for example. Absorptive particle  14  ( FIG. 3B ), for example, comprises a central core  32  surrounded or encapsulated by an absorptive component  34 , for example. Abrasive particles  12  and absorptive particles  14  are formed by applying a resin, polymer, glue or other suitable bonding agent to an exterior surface of cores  28 ,  32 , and then applying the abrasive component  30  and the absorptive component  34 , respectively, to the resin, polymer, glue or other suitable bonding agent coated on the exterior surface of cores  28 ,  30  in a conventional manner, e.g. mixing, sprinkling, etc.  
         [0031]     As the density of abrasive component  30  is generally greater than that of the absorptive component  34 , the density of core  32 , for the absorptive component  34 , is therefore selected to be greater in density than the density of core  28 , for the abrasive component  30 , so that the formed abrasive particle  12  and absorptive particle  14  have approximately the same or closely similar weight for particles of equal size. Core  28  may be, for example, a rubber core while core  32  may be, for example, a plastic core. Both cores  28 ,  32  may be any suitable material which allows the abrasive, absorptive, polishing, or other surface finishing or treating components to adhere to the exterior surface of the cores  28 ,  32  and provides a particle of a desired density.  
         [0032]     Forming media  11  from a stream of particles having approximately equal amounts of abrasive particles  12  and absorptive particles  14  facilitates blasting. Since abrasive particles  12  and absorptive particles  14  have approximately equal weights, due to their cores  28 ,  32  having different densities, continuous use of mixer or auger  4  in tank  2  is generally not necessary, once the media is uniformly mixed, in order to ensure that the mixed media  11  supplied to supply conduit  16  comprises the appropriate proportion of each type of particles, e.g. a 50-50 media blend, 60-40 media blend, a 75-25 media blend, a 25-35-45 blend, etc.  
         [0033]     During a blasting operation, the abrasive component  30 , of the abrasive particle  12 , removes material from the surface being treated by a rubbing and/or friction action which typically wears the abrasive component  30  from the exterior surface of core  28  and, over prolonged use, may eventually lead to exposure of core  28 . Once this occurs, abrasive particle  12  has lost its surface treatment effectiveness. It is to be appreciated, however, that core  28  is selected so as not to wear during use and thus it is substantially completely recyclable and can be recoated with abrasive component  30  and reused. This recoating will result in a substantial reduction in the cost of using media  11  and minimize disposal of any generated waste.  
         [0034]     Any contaminants on core  28  will be located on the exterior surface thereof and this facilitates easy cleaning of the surface prior to recoating of core  28 . In known prior art composite particles, which combine absorptive and abrasive components with one another in the same particle, the contaminants are absorbed by the absorptive component of the particle, which does not facilitate easy cleaning of the media and may lead to premature disposal or cleaning of the media being used to prevent the absorptive component of the media from recontaminating the surface being cleaned during subsequent use.  
         [0035]     A third embodiment of media  11  is shown in  FIGS. 4A and 4B . According to this embodiment, a plurality of small fibers  13 , such as nylon fibers, are added to abrasive component  30  and absorptive component  34  during coating of cores  28  and  32 . Some of the fibers  13  are completely imbedded within the abrasive component  30  and absorptive component  34 , while a portion of others of the fibers  13  partially project from the exterior surface of abrasive particles  12  and absorptive particles  14 . The portions of fibers  13  partially projecting from the exterior surface of these particles intermingle with fibers of adjacent particles, thereby assisting with preventing separation of the different particles  12 ,  14  from one another if mixing of the media is discontinued. Cores  28 ,  32  are selected to have a size preferably between a #10 screen and a #30 screen.  
         [0036]     In order to increase the speed of the blasting operation, abrasive particles  12  and absorptive particles  14  may be made relatively small, e.g. between {fraction (1/100)} and {fraction (1/8)} inches. The abrasive particles  12  and the absorptive particles  14  may also be agglomerated to increase their effective size and thereby enhance mechanical separation and/or facilitate recovery of the media.  
         [0037]     Turning now to  FIG. 5 , a third embodiment of the invention is shown. Blasting media applicator  1 ′ comprises two separate containers, i.e. container  36  which contains a first type or kind of particles, e.g. abrasive particles  12 , and container  40  which contains a second type or kind of particles, e.g. absorptive particles  14 , for example. Supply conduit  16  is connected at a first end thereof to the pressurized air supply source  18  and at a second end thereof to the blasting nozzle  22 . Metering device or means  38  is connected at a first end thereof to container  36  and at a second end thereof to air supply conduit  16 . Metering device or means  42  is connected at a first end thereof to container  40  and at a second end thereof to air supply conduit  16 . Stream  26 , comprising media  11  of both types of particles  12 ,  14  and pressurized air, is supplied to and directed by blasting nozzle  22  at the surface S to be cleaned.  
         [0038]     A second embodiment of the blasting nozzle, as well as the manner in which the media is supplied thereto, is shown in  FIGS. 6A and 6B . Blasting nozzle  44  is provided with a central discharge opening  46  located in a central portion of a discharge end face of nozzle  44 . In addition, a ring or annular discharge opening  48  is provided in an outer portion of the discharge end face of nozzle  44 . Central discharge opening  46  is supplied with a first type or kind of blasting particles, e.g. abrasive particles  12 , via a container, metering means, and air supply source only generally designated as  50 , conveyed to an end inlet of nozzle  44  via supply conduit  51 , while annular discharge opening  48  is supplied with a second type or kind of blasting particles, e.g. absorptive particles  14 , via a container, metering means, and air supply source only generally designated as  52 , conveyed to a side inlet of nozzle  44  via supply conduit  53 . During use, the two kinds of particles mix with one another so that the resultant stream  26  comprises a mixed media, i.e. mixture of abrasive particles  12  and absorptive particles  14 . Stream  26  is directed at the surface to be treated S where the particles  12 ,  14  provide the desired surface treatment.  
         [0039]     A fourth embodiment of the present invention is shown in  FIG. 7 . According to this embodiment, blasting device  20 ′ is connected to a first end of a supply conduit  16 ′ while the opposite end of supply conduit  16 ′ is connected to a discharge nozzle  22 ′. The blasting device  20 ′ contains and supplies absorptive particles  14 ′. Discharge nozzle  22 ′ extends through an aperture  55  provided in an upper portion of containment barrier  54 . Containment barrier  54  surrounds and seals containment area  56  around surface S, which is to be treated. Absorptive particles  14 ′ are projected by blasting device  20 ′ into containment area  56  and are at least partially suspended therein.  
         [0040]     Containment barrier  54  is more fully described in U.S. Pat. No. 5,823,860 issued on Oct. 20, 1998 and the subject matter of that patent is incorporated herein by reference.  
         [0041]     Blasting device  20 ″ is connected to a first end of a supply conduit  16 ″ while the opposite end of supply conduit  16 ″ is connected to a discharge nozzle  22 ″. The blasting device  20 ″ contains and supplies abrasive particles  12 ″. Discharge nozzle  22 ″ extends through an access port  57  provided in the containment barrier  54 , e.g. in a central portion of containment barrier  54 . Access port  57  is typically a flexible conical shaped member which allows nozzle  22 ″ to be pivoted at least about 900, relative to a central axis of the access port  57 , while also facilitating rotation, within containment area  56 , of about 360° so that the entire surface S can be treated.  
         [0042]     During use, abrasive particles  12 ″ are supplied by blasting device  20 ″ into containment area  56  which contains absorptive particles  14 ′ at least partially suspended in containment area  56 . The partial suspension of absorptive particles  14 ′ is enhanced by the turbulence created within containment area  56  by the air streams projected by blasting devices  20 ′,  20 ″ and by the rebounding of media  11  off the surface S and the surfaces of containment barrier  54 .  
         [0043]     Abrasive particles  12 ″ in the stream  26  are therefore mixed with the “suspended” absorptive particles  14 ′, and the abrasive particles  12 ″ contact, mix and carry therewith the “suspended” absorptive particles  14 ′ and form a combined media  11  which is conveyed toward the surface S and achieves the desired surface treatment thereof.  
         [0044]     Exhaust hose  66  is attached, at a first end thereof, to an outlet  67  provided in a lower portion of containment barrier  54 . A second end of exhaust hose  66  is connected to an inlet of a vacuum pump or other suction device  68 , for example a Dust Collector manufactured by IPEC Inc. of Rhode Island, U.S.A. The exhaust hose  66  and the suction device  68  create a negative pressure within containment area  56 , during use of the system, which removes airborne media and dust, any excess applied media, removed substance, material, contaminants, debris, etc. from containment area  56 . This negative pressure reduces the opportunity for media  11  and/or contaminants to escape from containment area  56  into the surrounding area by any crack or other opening in the containment barrier  54  so that the only available exhaust flow path is via exhaust hose  66 .  
         [0045]     During use, the media  11  of all four embodiments is supplied by suitable blasting or propelled means. Typically, the media  11  is conveyed by compressed air, or some other pressurized fluid such as water, or by known mechanical conveying means, against surface S which is to be treated. Media  11  then rebounds off the surface S and is collected and recovered by suction device  68 . Any contaminated absorptive particles which are collected can be separated and removed from the media for cleaning and subsequent reuse, or properly disposed of once the absorptive particles are fully contaminated and not recyclable. The abrasive component and/or any contaminants can also be separated and removed from the reusable media for proper disposal.  
         [0046]     By forming the media  11  from at least two separate and distinct types of particles, an operator is able to custom blend the media during use to achieve maximum surface treatment per pound of media. For example, if a first area of the surface to be treated requires substantial rust removal, the abrasive portion of the media  11  can be increased to facilitate such rust removal. Once that area is adequately treated, the operator can lower the proportion of the abrasive component of the media  11  and increase the proportion of the absorptive composition of the media, for example, to facilitate adequate grease or oil removal from another area of the surface S to be treated.  
         [0047]     It is to be appreciated that the media  11  may be formed of more than two distinct types or kinds of particles. When more than two types of particles are employed, more than two containers may be necessary, e.g. three, four or more separate containers may be required depending upon the application. Each of these containers would typically contain a different type of particle, which would then be mixed together forming media  11  to be applied to a surface S to be treated. The metering means of feed device for each container may be separately controlled (not shown in detail) so that the desired amount of each proportion of each particle type is easily obtainable and readily variable.  
         [0048]     The ability of an operator to custom blend the media, during use while at a jobsite, maximizes treatment of the surface per pound of media and minimizes the generation of waste which have to be disposed of as a result of the surface treatment.  
         [0049]     Since certain changes may be made in the above described media and blasting system, without departing from the spirit and scope of the invention herein involved, it is intended that all of the subject matter of the above description or shown in the accompanying drawings shall be interpreted merely as examples illustrating the inventive concept herein and shall not be construed as limiting the invention.