Abstract:
A particulate blasting apparatus includes a blast vessel having an interior for storing abrasive particulate. The blast vessel has an inlet for introducing a pressurized gas into the interior of the blast vessel and an outlet for allowing the passage of the pressurized gas and particulate. A flexible blast hose is coupled at one end to the outlet for directing particulate flow from the outlet and a blast nozzle is coupled to an opposite end of the blast hose. A metering valve regulates different amounts of particulate flow from the blast vessel through the outlet. A flow actuator is coupled to the metering valve for actuating the metering valve. A controller associated with the blast nozzle in communication with the actuator controls the actuator from the blast nozzle during blasting operations. The blasting apparatus may be used as part of a blasting system that includes a compressor unit for providing the pressurized gas. A method of blasting an area is achieved by controlling the amount of particulate provided to the blast nozzle from the blast nozzle through the controller associated with the blast nozzle while pressurized gas is flowing through the blast nozzle and directing a particulate flow from the blast nozzle to the area.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Patent Application No. 60/938,493, filed May 17, 2007, which is herein incorporated by reference in its entirety. 
     
    
     BACKGROUND 
       [0002]    During blasting operations using prior art abrasive blasting equipment, the operator directs a mixture of pressurized air and particulate abrasive material, such as soda, sand, etc., through a nozzle to the area requiring cleaning or blasting. The abrasive particulate is stored in a blast pot containing the particulate that is pressurized with air. The nozzle is typically connected to the blast pot through a length of flexible hose so that the nozzle may be used at various distances that are remote from the blast pot. 
         [0003]    Prior art blasting equipment utilizes an on/off control so that the blast stream can be stopped or started with no variation in the amount of particulate flow or pressure from the blast pot. In order to regulate the flow of particulate, the operator must stop the blasting operation and return to the blast pot so that the flow setting of the blast pot can be manually adjusted. The operator must then return to the blast nozzle, test the particulate flow from the nozzle and determine whether the particulate flow is adequate or optimal. If the flow is not optimal, the operator must return to the blast pot and continue this process until the proper particulate flow is achieved. As can be seen, this is an inconvenient and time consuming process. Furthermore, during a job, different degrees of particulate flow may be required or necessary at any given time to perform the blasting operation. In some instances, the particulate flow may be optimal for certain areas, but too low or too high for others. In many instances, proper optimization may not be seriously pursued by the operator because of the inconvenience of adjusting the abrasive flow. This may result in abrasive being wasted because it is either insufficient or excessive for the particular area being blasted or it provides an inadequate blasting job. 
         [0004]    Accordingly, what is therefore needed is a means for abrasive blasting wherein the amount of blasting media can be controlled remotely from the blast pot and during the blasting operation to overcome these shortcomings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0005]    For a more complete understanding of the present invention, and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying figures, in which: 
           [0006]      FIG. 1  is a side perspective view of a mobile abrasive particulate blasting system employing a blasting apparatus with a remote abrasive control in accordance with the invention; 
           [0007]      FIG. 2  is a front elevational view of the blasting apparatus of  FIG. 1 ; 
           [0008]      FIG. 3  is cross-sectional elevational side view of the blasting apparatus of  FIG. 2 , showing internal components of blast vessel of the blasting apparatus; 
           [0009]      FIG. 4  is an enlarged front perspective view of the upper portion of the blasting apparatus of  FIG. 2 , showing an actuator of the blasting apparatus; 
           [0010]      FIG. 5  is a plot of torque versus current and the rate of turning used in an actuator suitable for the blasting apparatus; 
           [0011]      FIG. 6  is a cross-sectional elevational view of one embodiment of a metering valve for use with the blasting apparatus, shown with the metering valve in an open position; 
           [0012]      FIG. 7  is a cross-sectional elevation view of the metering valve of  FIG. 5 , shown with the metering valve in a closed position; and 
           [0013]      FIG. 8  is a side perspective view of a blast nozzle of the blasting apparatus of  FIG. 1 , shown with a toggle switch for controlling the blasting apparatus. 
       
    
    
     DETAILED DESCRIPTION 
       [0014]    Referring to  FIG. 1 , an abrasive particulate blasting system  10  is shown. The blasting system  10  is shown as a mobile system that includes a trailer or frame  12  mounted on wheels  14 , so that the system may be readily transported to different locations. The system  10  may be a stationary system, as well. A compressor unit  16  for providing a pressurized gas is mounted or carried on the frame  12 . The pressurized gas is typically air, although other gases, such as nitrogen, carbon dioxide, etc. or mixture of gases, may also be used with the system  10 . Although the following description references air as the pressurized gas, it will be understood that other gases or gas mixtures may be used. 
         [0015]    The compressor unit  16  may be electrically powered from an outside power source or powered by a combustible fuel engine, such as diesel or gasoline. An electrical generator and/or battery (not shown) may be provided with those units or systems where combustible fuel engines are employed for supplying electrical power to the compressor unit  16  and/or other components of the system  10 , where electrical power is required. 
         [0016]    In the embodiment shown, a blast unit platform  18  is provided with the frame  12  for supporting or carrying a blast unit  20  of the system  10 . A dryer unit  22  may be provided with the system  10  and is shown mounted on a blast unit platform  18 . Because ambient air is typically used as the gas pressurized by the compressor  16 , it may contain moisture that can be detrimental to the system and materials used in the blasting operation. The dryer  22 , which is shown as a twin-fan air cooler with a moisture separator, facilitates cooling of the air and removal of such moisture from the pressurized air received from the compressor  16 . 
         [0017]    The blast unit  20  includes a blast pot or vessel  24  ( FIG. 2 ) that is supported on forward and rearward support members  26 ,  28  on the platform  18 . Wheels  30  may also be provided, as shown mounted to rearward support members  28 , for facilitating transport of the blast unit  20 . A handle  32  is shown mounted to the blast vessel  24 , so that the blast unit may be transported much like a hand truck or dolly. A releasable locking system (not shown) may be used to secure the blast unit  20  to the platform  18 . 
         [0018]    The blast vessel  24  ( FIG. 2 ) may have a variety of configurations, but in the embodiment shown, the blast vessel  24  has a generally cylindrical midsection  34 , a generally hemispherical or inverted dish-shaped upper portion  36  and a generally conical lower section  38 . An access port or opening  40  is provided in the wall of the blast vessel  24 , for accessing the interior of the vessel and to introduce abrasive particulate used. A cover or closure  42  is provided with the opening  40  to selectively close the opening. The closure  42  may be provided with a seal or seals and a locking mechanism suitable to withstand the high pressures used with the blast unit  22 . A pressure relief valve  44  may also be provided with the vessel  24  to facilitate release of the pressurized air within the vessel  24 . 
         [0019]    Referring to  FIG. 3 , pressurized air or other gas from the compressor  16  is directed into the interior of the blast vessel  24  through an elongated central conduit  46 . As shown, the conduit  46  extends from the exterior of the vessel  24  through an opening  48  in the upper portion  36  of the vessel  24 . A seal assembly  50  provided in the opening  48  provides a fluid tight seal around the conduit  46  so that the conduit  46  can be moved longitudinally within the opening  48  while preventing the escape of gas during use. 
         [0020]    In the embodiment shown, the upper end of the conduit  46  is coupled to a T-fitting  52 . A side inlet  54  of the T-fitting  52  is coupled to a length of flexible conduit  56 . The flexible conduit  56  is connected through elbow fitting  58  to a vertical length of flexible conduit  60 . The flexible conduit  56 , elbow  58  and flexible conduit form an inlet conduit  62  of the blast unit  20 . Various conduit sections, couplings or fittings may be used to form the inlet conduit  62 . The couplings and fittings may facilitate removal and replacement of various lengths of conduit and other components of the inlet conduit  62 , if necessary. 
         [0021]    Referring to  FIG. 4 , an actuator bracket  64  is mounted to the exterior of the upper portion  36  of the blast vessel  24 . The actuator bracket  64  has a generally U-shaped configuration, as shown, having legs  66 ,  68  joined by a transverse cross member  70 . Bracket mounting flanges  72  may be provided, such as by welding, on the upper portion  36  of the vessel  24  for mounting of the bracket  64 , such as with bolts or fasteners  73 , through the legs  66 ,  68 . The bracket  64  is configured so that the cross member  70  extends over the upper end  74  of the T-fitting  52 . The cross member  70  of the bracket  64  is provided with a hole or opening  76  that is centered or aligned directly above the upper end  74  of the T-fitting  52 . An upright guide member or post  78  is provided on the bracket  64  and extends vertically from the upper surface of the cross member  70  and is laterally spaced a distance from the opening  76 . 
         [0022]    A rotary valve actuator  80  is provided with the blast unit  20  and is mounted to the actuator bracket  64 . The actuator  80  is provided with an actuator housing  81  for housing the internal components of the actuator  80 . As shown in  FIG. 4 , the actuator  80  rotatably drives an externally, helical threaded drive member  82  that is received within and passes through the opening  76  of the cross member  70 . The opening  76  of the cross member  70  is also provided with helical internal threads that correspond to and engage the helical threads of the drive member  82 . The lower end of the drive member  82  engages the upper end  74  of the T-fitting  52  so that the drive member  82  rotates freely relative to the T-fitting  52 . The upper end  74  of the T-fitting is plugged so that no pressurized air can pass through the upper end  74 . 
         [0023]    Coupled to the actuator housing  81  is an actuator arm  84 . The actuator arm  84  is provided with a guide member receiving portion  86 , which may be in the form of an aperture or slot, which engages the guide member  78 . The guide member  78  prevents the actuator  80  from rotating relative to the bracket  64  when actuated so that the drive member  82  is rotated and not the actuator housing  81 . The guide member  78  allows the actuator  80  to move linearly up and down, however. 
         [0024]    In the embodiment shown, the actuator  80  is an electric actuator. In the present embodiment, torque limiting software may be provided with the actuator  80  to prevent damage to the actuator in the case of “hard stops” due to mechanical blockage. This may also limit the amount of torque applied to limit damage to the valves of the blast unit  20  when they are fully seated. A suitable torque is that shown in  FIG. 5 , with the amount of torque increase with the amount of current supplied. The actuator  80  may use a continuous or digital signal. Power and electrical signals to the actuator are supplied through wiring  88 . The actuator  80  may also have a limiter that limits the degree of actuation or number of rotations that are provided to a preselected level. Although the actuator  80  has been shown and described as an electrical rotary actuator, other actuators may be used as well. In some embodiments, a linear actuator may be used to impart a linear motion to actuate valves of the blast unit  20 . Additionally, the actuator may be hydraulically, pneumatically or mechanically driven and/or controlled. 
         [0025]    As pressurized air is introduced into the interior of the blast vessel  24  through central conduit  46 , it is directed downward through the conduit  24  to a nozzle  90  that is coupled to the lower end of the conduit  46 , as shown in  FIG. 3 . The conduit  46  is provided with one or more small holes or apertures  92  near the upper end of the conduit  46 . The holes  92  allow the air pressure within the interior of the blast vessel  24  exterior of the conduit  46  and the interior of the conduit equalize. 
         [0026]    Referring to  FIGS. 6 and 7 , the lower end of the blast vessel  24  terminates in a flanged end  94  having a central opening  95 . Coupled to the flanged end  94  is a flange assembly  96  having an internally threaded central opening  98  to which is threaded an externally threaded union member  100 . The union member  100  has an internally threaded central opening  102  and external nut flats  103  to facilitate coupling of the union member  100  with a wrench or other tool. An outlet elbow pipe fitting  104  having an externally threaded upper end  106  engages and is coupled to the central opening  102  of the union member  100 . The lower end  108  of the elbow fitting  104  is also threaded to facilitate coupling to other pipe fittings. The opening of the upper end  106  of the elbow fitting  104  forms an outlet opening of the blast vessel  24 . 
         [0027]    As shown in  FIGS. 6 and 7 , the nozzle  90  cooperates with the upper end  106  of the elbow pipe  104  to act as a particulate flow valve, which is designated generally at  109 . The exterior of the nozzle  90  is tapered in diameter. As an example, the degree of taper (length/diameter) for the exterior of the nozzle  104  may be from about 0.5 to about 1.5. The interior  110  of the nozzle  90  is also tapered in diameter so that the flow within the nozzle  90  is constricted within the interior of the nozzle  90 . The degree of taper or constriction within the interior may be the same or different as the exterior of the nozzle  90 . The lower end of the nozzle  90  is also smaller in diameter than the outlet  106  so that the lower end of the nozzle  90  can extend a distance within the outlet  106 . As shown in  FIG. 6 , this provides a gap  112  between the exterior of the nozzle  90  and opening of the upper end  106  when the nozzle is in a raised position. As pressurized air flows through the nozzle  90 , a venturi effect is created so that the pressure within nozzle is reduced. This causes the abrasive particulate that is stored in the blast vessel  24  to be drawn through the gap  112  and into the elbow  104 . By lowering and raising the nozzle  90  relative to the opening  106 , the flow of particulate may be increased or decreased. 
         [0028]    It should be noted that when a range is presented herein as an example, or as being useful, suitable, etc., it is intended that any and every amount or point within the range, including the end points, is to be considered as having been stated. Furthermore, when the modifier “about” is used with reference to a range or numerical value, it should also be alternately read as to not include this modifier, and when the modifier “about” is not used with reference to a range or numerical value, the range or value should be alternately read as including the modifier “about.” 
         [0029]    When the nozzle  90  is fully lowered the exterior of the nozzle  90  will seat against the upper end  106  of the fitting  104  so that the gap  112  ( FIG. 6 ) is eliminated, as shown in  FIG. 7 . This completely cuts off flow of particulate, but allows pressurized air to continue to flow through the nozzle and elbow fitting  104 . 
         [0030]    Referring to  FIG. 3 , a length of flexible hose or conduit  114  is coupled to the lower end  108  of the elbow  104  through valve assembly  116 . The valve assembly  116  may be an electronically actuated ball valve or other type of valve and is used start and stop the flow of the air and/or particulate/air mixture from the blast unit  20 . The flexible hose may have a variety of different lengths depending upon the blasting application, but is typically from about 5 ft. (˜1.5 meters) to about 200 ft. (˜61 meters) or more. The hoses may be provided in lengths (e.g. 50 ft., 15 meters) that are coupled together. In this way, different hose lengths may be provided. 
         [0031]    Referring to  FIG. 8 , a blast nozzle  118  is coupled to the other end of the hose  114 . The nozzle  118  is configured for providing a particulate blast spray, such as those that are known to those skilled in the art. A controller  120  is mounted to or otherwise provided with the nozzle  118  so that it is in an accessible proximity to the user when handling the nozzle  118 . In the embodiment shown, the controller  120  is mounted to the nozzle  118  itself. 
         [0032]    A pair of toggle switches  122 ,  124  is provided with the controller  120 . Although the toggle switches  122 ,  124  are shown in a side by side arrangement, a second controller or controller housing for each toggle switch  122 ,  124  may provided as well. The controllers or controller housings may be staggered along the length of the nozzle  118  or hose  114 , one behind the other, to facilitate the use of both hands to control the switches  122 ,  124  while handling the nozzle. The toggle switches  122 ,  124  are for controlling the actuator  80  and valve assembly  116 , respectively. Electrical wiring or signal cables  126 ,  128  for the toggles  122 ,  124 , respectively, lead from the nozzle  118  to a control panel or circuit box  130 , which may be located on the unit blast unit  20 . For the actuator  80 , the toggle  122  may be a three-wire switch wherein operating the toggle  122  reverses current flow to reverse the actuator  80 . The toggle  122  may be biased so that release of the toggle  122  brings it to a centered or neutral position upon release. The toggle  124  for the valve assembly  116  may be a two-wire switch where the toggle  124  merely performs a cutoff or on/off function. Although the toggle switch  124  is described as a cutoff switch, this may also be configured to provide variable control of the valve assembly  116 , such as with the toggle  124 . Alternatively, the toggle switch  124  or another switch or control (not shown) provided with the nozzle  118  may be used to regulate a regulator valve (not shown) to regulate the compressed air supplied from the compressor  16  to thus adjust the air pressure to the unit  20 . 
         [0033]    Electrical power to the actuator, toggles, control panel, valve assembly  116 , etc. may be provided from a battery power source (not show) or it may be powered from the generator or power source of the compressor unit  16  or other external power source. Releasable plugs or other couplings may be used to couple the cables  126 ,  128  to the control panel  130 . The cable  88  from the actuator  80  and electrical cable or wiring  134  for the valve assembly  116  may also be plugged or releasably coupled to the control panel  130 . Other configurations for wiring of the system may be used as well. 
         [0034]    Additionally, where hydraulic or pneumatic actuation is used, the signal cables  126 ,  128  may be replaced with fluid or air lines. Such hydraulic or pneumatic actuation may be particularly useful in environments, such as around combustible fuels, where electrical sparks or arcing of electrical components may create a hazard. A hydraulic pump or air motor (not shown) may be provided with the system  10  to facilitate operation of such actuation. 
         [0035]    In certain applications, control of the blast unit  20  may be provided wirelessly from the nozzle  118 , such as through infrared, laser, radio frequency or other wireless signals that may be suitable for remote wireless control. A wireless signal receiver (not shown) may be provided with the unit  20  to thereby actuate the actuator  80  and/or valve  116 . 
         [0036]    In operation, the blast vessel  24  is filled with a particulate abrasive through the access port  40  and the closure  42  is secured. The particulate abrasive may be sodium bicarbonate (soda or baking soda), sand or other abrasive particulate suitable for performing blasting operations. In many applications, soda is used as the abrasive particulate. The abrasive will tend to collect in the conical lower section  38  of the blast pot  24  so that it is fed towards the opening  106 . 
         [0037]    The compressor unit  16  provides pressurized air or gas, which has been cooled and dried through dryer unit  22 , to the blast unit  20  through inlet conduit  62 . Initially, the valve assembly  116  ( FIG. 7 ) and the particulate metering valve  109  may be fully closed. The compressor  16  provides sufficient pressure for the blasting operation. This pressure may vary, but typical pressures are from about 30 psi (206 kPa) to about 180 psi (1241 kPa) or more. All components and fittings of the blast unit should be rated for the particular pressure being used. 
         [0038]    To begin blasting, the operator may actuate the valve assembly  116  through toggle switch  124  so that the valve assembly  116  is opened to allow pressurized air to flow from the nozzle  90  to flow through the elbow  104  through the hose  114  and nozzle  118 . When the blast unit is pressurized, the central conduit  46  will tend to lift or raise up. Lifting, however, is prevented by the engagement of the drive member  82  with the upper end  74  of the T-fitting  52 . Even when the metering valve  109  is fully closed, the pressurized air flow flowing through the hose and nozzle is not significantly affected. The operator may then open the metering valve  109  through toggle switch  122 . Upon operation of the toggle switch  122 , the actuator  80  will rotate the threaded drive member  82  so that the T-fitting  52  raises, thereby raising the conduit  46  so that the nozzle  90  is raised to open the metering valve  109 . The flexible sections  56 ,  60  of the inlet conduit  62  provide an amount of play to facilitate movement of the T-fitting  52 . When the metering valve  109  is opened, soda or other abrasive particulate is drawn into the gap  112  so that the abrasive is delivered through the hose  114  to the nozzle  118 , where it may be directed to an object or surface to be blasted. In the embodiment shown, the actuator  80  may only provide about ½ inch (1.27 cm) or less to about 1 inch (2.54 cm) or more of linear movement. This may vary, however, depending upon the metering valve configuration and metered materials employed. 
         [0039]    Although one type of blast unit and metering valve is shown, different blast units and metering valves may be used with the remote control system described herein. U.S. Pat. Nos. 2,261,565 and 7,134,945, each of which is incorporated herein in its entirety, describe blasting systems that may be used with the remote actuating system. Additionally, the abrasive metering valve may have a variety of different configurations, such as a ball or ½ turn valves, globe valves, needle valves, etc. One example of a suitable valve for use as the abrasive metering valve is that described in U.S. Pat. No. 6,607,175, which is incorporated by reference in its entirety. 
         [0040]    If the amount of abrasive is not suitable, the operator can further open or close the metering valve  109  by means of the toggle  122 . The abrasive flow rate may vary, but a typical abrasive flow rate for soda, for example, is about 50 lb/hr to about 100 lb/hr (22.7 kg/hr to 45.4 kg/hr). Pushing the toggle  122  in one direction may cause the actuator  80  to rotate in one direction to close the metering valve  109 , while pushing the toggle  122  in the other direction will reverse the actuator rotation to open the metering valve. In one embodiment, the rotary metering valve actuator  80  may provide a constant rate of rotation so that the degree of rotation is controlled through a timed response. Thus, holding the toggle switch  122  down will actuate the actuator for a certain period of time to provide the desired degree of rotation, thus opening or closing the metering valve  109  a selected degree. In another embodiment, the actuator  80  may provide a change of rotation rate that is proportional to or based upon the character of the signal provided from the toggle switch  122 . Thus, for example, movement of the toggle  122  only slightly may produce a slow rate of rotation. If the toggle  122  is moved more, a higher rotation rate may be achieved. Thus, the amount of abrasive metered may be performed more slowly or quickly. The same operation may be provided with linear actuators or similar devices. 
         [0041]    In the above-described manner, the operator can provide the desired amount of abrasive flow to the nozzle for carrying out the blasting operation without having to return to the blast vessel  24  to adjust the abrasive flow. This saves time, reduces the amount of abrasive that may be wasted and provides on demand the optimal flow of abrasive suitable for the blasting operation. 
         [0042]    While the invention has been shown in only some of its forms, it should be apparent to those skilled in the art that it is not so limited, but is susceptible to various changes and modifications without departing from the scope of the invention. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the scope of the invention.