Patent Publication Number: US-2017361350-A1

Title: Particulate spray booth having a sealed particulate spray device booth wall opening

Description:
TECHNICAL FIELD 
     This application relates to a particulate spray system, and more particularly to a particulate spray system with a particulate spray booth having a sealed particulate spray device booth wall opening to increase the efficiency of the particulate spray system by requiring less energy to exhaust powder overspray. 
     BACKGROUND 
     The present disclosure relates to particulate spray systems having one or more particulate spray devices that spray particulate materials onto workpieces inside the spray booth of the particulate spray system, wherein at least some of the particulate material must be collected from the spray booth and recovered for reuse. The particular spray device could spray particular materials onto the workpiece, such as for sandblasting the workpiece, for example. In a particular preferred embodiment, the particulate spray device could spray powder coating material in a powder coating material spray booth. 
     Powder coating material booths typically include openings in the booth walls to allow for powder spray devices to pass through and into the interior of the booth. To collect the excess powder following coating of an article or during a color change procedure, suction means are typically used. However, the openings in the booth walls can be large to allow for manual or automatic spray coating devices, resulting in the escape of overspray powder and requiring a tremendous amount of energy to power the suction means. To address this issue, a solution is needed to seal the openings to prevent the escape of overspray powder and more efficiently create a vacuum condition within the booth. Accordingly, this seal solution will result in a decreased overall cost of use of the booth, whether the booth is used to spray powder coating material or particulate material such as sandblasting materials. 
     SUMMARY 
     In one preferred embodiment, the particulate spray system is a powder coating material spray system having a powder coating spray device surrounded by a flexible boot element. In one aspect, a powder coating material spray system may include a booth comprising a ceiling, a floor, and side walls defining an interior of the booth, wherein the booth defines an opening from the interior of the booth to an exterior of the booth. The system may further include a powder spray device received through the opening, the powder spray device comprising a body and a nozzle through which powder coating material is sprayed into the interior of the booth, wherein the nozzle and at least part of the body are disposed in the interior of the booth. The system may further include a flexible boot element having a proximal end and a distal end opposite the proximal end, the proximal end attached to a periphery of the opening to form a first seal and the distal end attached to the at least part of the body of the powder spray device disposed in the interior of the booth to form a second seal. 
     In an aspect, the powder coating material spray system may further include a powder recovery system comprising an overspray intake communicating with the interior of the booth and a suction means for drawing overspray powder from the interior of the booth into the overspray intake. The powder spray device may be moved by a robotic arm situated on the exterior of the booth. 
     In an aspect, the boot element may form a conical shape tapering from a first diameter at the proximal end to a second diameter at the distal end, the first diameter being greater than the second diameter. For example, the first diameter may be at least twice the second diameter. 
     In another aspect, the first seal and the second seal may each be hermetic seals. 
     In an aspect, at least one of the proximal end and the distal end of the boot element may be configured to attach, respectively, to the periphery of the opening or the body of the powder spray device via a lever-operated clamp, an elastic band, a zipper, one or more clips, or a hook-and-loop system. In an aspect including a zipper, the boot element may comprise a flap covering the zipper. 
     In another aspect, the distal end of the boot element may be configured to attach to the body of the powder spray device via a rotatable bearing. In such an aspect, the nozzle may include an outlet through which the powder coating material is sprayed, the outlet configured as an elongate slit. 
     In yet another aspect, the boot element may comprise at least one of polyurethane, neoprene, silicone, and latex. 
     In another preferred embodiment, the particulate spray system is a system for spraying sandblasting materials onto a workpiece inside the booth. The spray device is surrounded by a flexible boot element. In one aspect, the spray system may include a booth comprising a ceiling, a floor, and side walls defining an interior of the booth, wherein the booth defines an opening from the interior of the booth to an exterior of the booth. The system may further include a spray device received through the opening, the spray device comprising a body and a nozzle through which particulate material is sprayed into the interior of the booth, wherein the nozzle and at least part of the body are disposed in the interior of the booth. The system may further include a flexible boot element having a proximal end and a distal end opposite the proximal end, the proximal end attached to a periphery of the opening to form a first seal and the distal end attached to the at least part of the body of the spray device disposed in the interior of the booth to form a second seal. 
     In an aspect, the spray system may further include a recovery system comprising an overspray intake communicating with the interior of the booth and a suction means for drawing particulate material that has already been sprayed from the spray device from the interior of the booth into the exhaust. The spray device may be moved by a robotic arm situated on the exterior of the booth. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The following detailed description is better understood when read in conjunction with the appended drawings. For the purposes of illustration, examples are shown in the drawings; however, the subject matter is not limited to the specific elements and instrumentalities disclosed. In the drawings: 
         FIG. 1  is a perspective view partly cut away of a powder spray booth in accordance with an embodiment. 
         FIG. 2  is a side view of the powder spray booth of  FIG. 1  and an associated robotic arm in accordance with an embodiment. 
         FIG. 3  is a side view of a powder spray booth and an associated powder recovery system. 
         FIG. 4  is a close-up view of a boot element disposed on a spray device in accordance with an embodiment. 
         FIG. 5  is a close-up view of a boot element disposed on a spray device in accordance with an embodiment. 
         FIG. 6  is a perspective view of a boot element in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Although this disclosure details a powder coating material spray booth, it is understood that the teachings below can be applied to other particulate material spraying systems, such as a system for spraying sandblasting materials onto workpieces within the booth, such as to remove coatings from the workpieces or clean them. 
     Disclosed herein are systems and apparatus for providing a flexible boot element for use in conjunction with a movable spray device of a substantially sealed powder spray booth. The boot element may be attached to both the spray device and a wall of the powder spray booth such that the boot element provides a seal between the interior of the powder spray booth and the exterior of the powder spray booth while still allowing sufficiently free movement of the spray device to execute its spray function. For example, the boot element may be configured as a generally conical formation in which the larger end of the boot element is sealed to the opening of the powder spray booth through which the spray device projects and the smaller end of the boot element is sealed to the spray device. 
       FIGS. 1 and 2  depict an illustrative powder spray booth  2  with ceiling (not shown), side walls  4 , end walls  6 , and a floor  10  defining an interior and an exterior of the spray booth  2 . While the spray booth  2  is depicted in  FIG. 1  without the foreground side wall  4  and end wall  6 , it will be understood that the interior of the spray booth  2  is substantially sealed from the exterior of the spray booth  2 . The spray booth  2  may further be configured with a conveyor (not shown) from which objects may be suspended and conveyed through the interior of the spray booth  2  for coating with powder by one or more spray devices  16 . 
     In some aspects, the ceiling, side walls  4 , end walls  6 , and/or floor  10  of the spray booth  2  may be made from a non-conducting material, such as plastic. By using plastic or other non-conductive material, the powder sprayed from the spray device  16 , which in some applications may be electrostatically charged, will have a reduced tendency to adhere to the surfaces of the spray booth  2 . Accordingly, the powder not adhering to the spray object (i.e., overspray powder) will fall under gravity and collect on the floor  10  or other lower portions of the spray booth  2 . For durability, the floor  10  and/or surfaces on which an operator will walk may instead be made of stainless steel. 
     One or more openings  12  may be defined in the side wall  4  (or other surface defining the interior of the spray booth  2 ) to allow a respective spray device  16  to project into the interior of the spray booth  2 . The spray device  16  may be controlled by a human operator (not shown) or by a robotic arm  14  (as shown in  FIGS. 1 and 2 ). The robotic arm  14  may control the various movements of the spray device  16 . For example, the robotic arm  14  may move the spray device  16  horizontally and/or vertically within the confines of the opening  12 . Further, the robotic arm  14  may also adjust the vertical and/or horizontal angle at which the spray device  16  is tilted. Further still, the robotic arm  14  may also move the spray device  16  in the direction into and/or out of the spray booth  2 . Finally, the robotic arm  14  may rotate the spray device  16  about an elongate axis of the spray device  16 . 
     The spray device  16 , or portion thereof, projecting into the interior of the spray booth  2  is surrounded by a boot element  13  configured to attach to the spray device  16  and the periphery of the opening  12  to seal the interior of the spray booth  2 . The seal provided by the boot element  13  may serve to prevent airborne overspray powder from exiting the interior of the spray booth  2  and potentially contaminating the exterior, the robotic arm  14 , and/or human operators. Further, the seal provided by the boot element  13  may also facilitate a suction and/or airflow created by a powder recovery system  34 . The spray device  16  and the boot element  13  will be described in additional detail with reference to  FIGS. 4-6 . 
     With additional attention to  FIG. 3 , the spray booth  2  is provided with the powder recovery system  34  to remove and recover overspray powder that did not adhere to the spray object. By way of example, the spray booth  2  is configured with an overspray intake  18  located in a corner of the spray booth  2 . A current of exhaust air is provided within the spray booth  2  and into the overspray intake  18  to draw in overspray powder. Rising there above is a duct  20  which leads to additional components of the powder recovery system  34 . Although the overspray intake  18  and the duct  20  are depicted in  FIG. 1  as being positioned on the same side of the spray booth  2  as the opening  12  and the spray device  16 , the configuration of the spray booth  2  is not so limited. For example, the overspray intake  18  and the duct  20  may be positioned on an opposite side of the spray booth  2  as the opening  12  and the spray device  16 , as depicted in  FIG. 3 . 
     The powder recovery system  34  may include a cyclone separator  36  that is connected to the duct  20 . In the cyclone separator  36 , the overspray powder is separated from the air-powder mixture drawn from the spray booth  2  via the duct  20 . Under the influence of centrifugal and gravitational forces, the overspray powder falls to the bottom of the cyclone separator  36  where it may be collected in a container for re-use. The exhaust air from the cyclone separator  36  which, during normal operation of the spray booth  2  contains only a small amount of overspray powder, passes through a connector pipe  38  to a powder filter unit  40 , which is sometimes called an after filter. The powder filter unit  40  includes therein one or more filter elements, such as one or more filter cartridges  42 , which filter out the remaining overspray powder in the exhaust air from the cyclone separator  36 . The cleaned exhaust air is then drawn out of the filter unit  40  and discharged into the atmosphere by a fan  44  mounted at the top of the filter unit  40 . Powder collected in the filter unit  40  may also be collected for re-use. 
     It will be appreciated that the action of the fan  44  provides the current of exhaust air within the spray booth  2  to draw the overspray powder into the overspray intake  18 . The larger the area of any openings in the spray booth  2  (e.g., an unsealed opening  12  for the spray device  16 , an opening of a conveyor slot, etc.), the greater the size of the fan  44  required to pull sufficient air through those openings to keep the overspray powder within the spray booth  2  and collect it in the powder recovery system  34 . In determining the size of the fan  44 , the width and length of the conveyor slot at the top of the spray booth  2 , the size of the openings at the entrance and exit of the spray booth  2  and/or the size of all openings in the sidewalls of the booth, such as the openings  12  for the spray guns  16  to project within the spray booth  2 , must all be considered in order to achieve the desired CFM (cubic feet per minute) air flow rate into the spray booth  2  through these openings. By using the boot element  13  to provide a seal to the opening  12  through which the spray device  16  is inserted into the spray booth  2 , this large opening into the spray booth  2  can be removed from the calculation of the CFM air flow rate required to pull enough air into the spray booth  2  to keep the overspray powder in the spray booth  2  and collect overspray powder in the powder recovery system  34 , resulting in a lower required CFM air flow rate than would be the case if the opening  12  were not sealed. This lower CFM air flow rate translates into a smaller fan  44  that can be provided to maintain the necessary airflow through all the spray booth openings to maintain overspray powder within the spray booth  2  and collect it in the powder recovery system  34 . Accordingly, by reducing the size of the fan  44  in accordance with the teaching of this disclosure, energy costs can also be reduced as well as the cost of the fan  44 . 
     Referring again to  FIGS. 1 and 2 , the floor  10  of the spray booth  2  is configured with two sloping portions  22  on either side thereof. The upper edges of the sloping portions  22  are flush with the respective side wall  4 . The lower edges of the sloping portions  22  are set apart from one another to define a trough  24  therebetween to collect overspray powder descending from the sloping portions  22 . Vertical walls  23  extending from the lower edges of the sloping portions  22  to the floor  10  further define the trough  24 . A cutaway  25 , corresponding with the location of the overspray intake  18 , is included in the vertical wall  23  to provide a connection between the overspray intake  18  and the trough  24  and thus also the rest of the interior of the spray booth  2 . 
     A diverter plate  26  is positioned in the trough  24  at the end where the overspray intake  18  is located and extends from that end. The length of the diverter plate  26  is preferably equal to the distance from the end of the spray booth  2  to the center line of the first spray device  16  relative to that end of the trough  24 , plus an offset. The offset may suitably be of the order of 200 mm. The diverter plate  26  is suitably spaced from the lower edges of the sloping portions  22  to define slots  27  therebetween. The diverter plate  26  is detachably supported on its underside by tabs (not shown) affixed to the lower edges of the sloping portions  22  and is mounted to the end wall  6  via one or more hinges  30  to allow it to be pivoted up and against the end wall  6 . The diverter plate  26  is configured with a pattern of holes  28  therein. The holes  28  are elongate in the lengthwise direction of the diverter plate  26  and hence also the spray booth  2 . 
     In use, one or more of the spray devices  16  are employed to apply powder to objects passing through the spray booth  2 . Airborne overspray powder is extracted from the interior of the spray booth  2  on the current of exhaust air produced by the fan  44  of the powder recovery system  34  via the overspray intake  18  and duct  20 . Overspray powder which falls out of the transport air provided by the powder recovery system  34  will be deposited on the floor  10  of the spray booth  2  and so on the sloping portions  22 , the bottom of the trough  24 , and the diverter plate  26 . The flow of exhaust air caused by the powder recovery system  34  along the trough  24  will tend to draw deposited overspray powder on the upper surface of the diverter plate  26  down into the trough  24  there below either through the holes  28  or the slots  27  between the sloping portions  22  and the diverter plate  26 . 
     The cleaning operation which is performed, such as when the color of the powder is to be changed, will now be described. The spray devices  16  are shut off and any access points to the interior of the spray booth are closed or sealed off. The diverter plate  26  is pivoted up against the adjacent end wall  6 . An operator, preferably using an air hose, begins at the opposite end of the spray booth  2  from the duct  20  and moves along the spray booth  2  blowing the deposited overspray powder which remains therein from all wall and floor surfaces and the surfaces of the diverter plate  26 , the duct  20 , and the overspray intake  18 . As the powder is blown off of the surfaces of the spray booth  2 , it is drawn into the duct  20  by the current of exhaust air provided via the overspray intake  18 . 
     With additional reference to  FIGS. 4 and 5 , the spray device  16 , or portion thereof projecting through the opening  12 , is situated within the boot element  13 . In particular, an elongate body  19  of the spray device  16  substantially projects through the opening  12  and, therefore, also through the boot element  13 . A nozzle  17  is disposed at one end of the elongate body  19  of the spray device  16 . The nozzle  17  includes an outlet  21  through which powder is sprayed. In some aspects, such as depicted in  FIGS. 4 and 5 , the outlet  21  may be configured as an elongate slit such that the spray pattern therefrom is similarly elongated (as opposed to a circular spray pattern). In such an aspect, the spray from the outlet  21  would be affected by the rotational position of the spray device  16 . 
     The boot element  13  depicted in  FIGS. 4-6  is configured in a generally conical or frusto-conical shape, but may alternatively be formed in a hemispherical, frusto-hemispherical, pyramidal, or frusto-pyramidal shape in other aspects. Accordingly, the boot element  13  has a proximal end  14 A with a diameter (or width) D 1  and a distal end  14 B, opposite the proximal end  14 A, with a diameter (or width) D 2 . The proximal end  14 A is coupled with a periphery  29  of the opening  12  in the side wall  4 , such as the interior of the side wall  4  surrounding the opening  12 . The distal end  14 B is coupled with the spray device  16 , such as around the circumference of the elongate body  19  near the nozzle  17 . Since the opening  12  in the side wall  4  will typically be sized to allow sufficient movement of the spray device  16 , the diameter D 1  of the proximal end  14 A of the boot element  13  will also typically be greater than the diameter D 2  of the distal end  14 B of the boot element  13 . For example, the diameter D 1  of the proximal end  14 A may be at least twice as wide as the diameter D 2  of the distal end  14 B. 
     To provide a seal of the interior of the spray booth  2 , the proximal end  14 A of the boot element  13  is coupled with the periphery  29  of the opening  12  in a manner that provides a substantially air-tight seal with the periphery  29  of the opening  12 . Advantageously, the proximal end  14 A of the boot element  13  may also be releasably coupled with the periphery  29  of the opening  12  to facilitate easy decoupling of the boot element  13  and/or the spray device  16  with the side wall  4 . Further, the distal end  14 B of the boot element  13  is coupled with the spray device  16  to similarly provide a substantially air-tight seal with the spray device  16 . The coupling of the distal end  14 B of the boot element  13  and the spray device  16  may also be accomplished in a manner that allows easy release. 
     As shown in  FIG. 4 , the proximal end  14 A of the boot element  13  and/or the periphery  29  of the opening  12  may be configured with a zipper  300  to releasably couple the proximal end  14 A and the periphery  29  of the opening  12 . The zipper  300  is configured with a flap  302  that is used to cover the teeth and pull of the zipper  300 . The flap  302  may serve to enhance the seal provided by the zipper  300  and/or prevent overspray powder from clogging the zipper  300 . Although not depicted as such in  FIG. 4 , the distal end  14 B of the boot element  13  and/or the spray device  16  may also be configured with a zipper. 
     As depicted in  FIG. 5 , the proximal end  14 A of the boot element  13  may be configured with a lever-operated clamp  400  to releasably couple the proximal end  14 A of the boot element  13  with the periphery  29  of the opening  12  in the side wall  4 . The clamp  400  utilizes a lever  405  that engages a baseplate  410 , via a hinge  415 , to couple the proximal end  14 A to the periphery  29  of the opening  12 . To release the proximal end  14 A from the periphery  29  of the opening  12 , the lever  405  is disengaged from the baseplate  410 . A flap  402  covering the clamp  400  may also be used to enhance the seal provided by the clamp  400  and protect the clamp  400  from overspray powder. The distal end  14 B of the boot element  13  may be similarly coupled with the spray device  16  using a clamp. 
     Other than the aforementioned zipper  300  and clamp  400 , other types of connectors for coupling the boot element  13  with the periphery  29  of the opening  12  and/or the spray device  16  include clips, snaps, elastic band, or hook-and-loop fasteners. 
     The boot element  13  may be formed of any flexible material suitable to allow movement of the spray device  16  and to provide a substantially air-tight seal of the interior of the spray booth  2  from the exterior of the spray booth  2 . Exemplary materials of which the boot element  13  may be constructed include tight-woven fabric, polyurethane, neoprene, silicone, and/or latex. 
     In one aspect, depicted in  FIGS. 4 and 5 , the distal end  14 B of the boot element  13  is rotatably coupled with the spray device  16 , such as via a rotatable bearing  31 . The bearing  31  allows the spray device  16  to be rotated about an axis of the spray device  16 , such as by the robotic arm  14 , without entangling or twisting the boot element  13  with the spray device  16 . It will be appreciated that the bearing  31  is also hermetically sealed so that exterior of the spray booth  2  remains sealed from the exterior of the spray booth  2 . 
     It will be apparent to those skilled in the art that various modifications and variations may be made without departing from the scope or spirit. Other implementations will be apparent to those skilled in the art from consideration of the specification and practice disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit being indicated by the following claims.