Abstract:
A particle blast apparatus transport is capable of generating granular sized particles and delivering them without substantial storage to a single hose feeder assembly. The apparatus is configured to be used with solid blocks of cryogenic material, such as carbon dioxide, and with individual pellets of such material.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to U.S. Patent App. No. 61/608,639, filed Mar. 8, 2012 and U.S. patent App. No. 61/594,347, filed Feb. 2, 2012, the disclosures of which are hereby incorporated by reference in their entirety. 
    
    
     TECHNICAL FIELD 
     The present invention relates generally to particle blasting using cryogenic material, and is particularly directed to a method and device involving blasting with carbon dioxide blast media, such as pellets or particles, which are delivered entrained in a high flow of transport gas with substantially no storage of the carbon dioxide media. 
     BACKGROUND OF THE INVENTION 
     Carbon dioxide blasting systems are well known, and along with various associated component parts, are shown in U.S. Pat. Nos. 4,744,181, 4,843,770, 4,947,592, 5,018,667, 5,050,805, 5,071,289, 5,109,636, 5,188,151, 5,203,794, 5,249,426, 5,288,028, 5,301,509, 5,473,903, 5,520,572, 5,571,335, 5,660,580, 5,795,214, 6,024,304, 6,042,458, 6,346,035, 6,447,377, 6,695,679, 6,695,685, and 6,824,450, all of which are incorporated herein by reference. Additionally, U.S. patent application Ser. No. 11/344,583, filed Jan. 31, 2006, for PARTICLE BLAST CLEANING APPARATUS WITH PRESSURIZED CONTAINER, U.S. patent application Ser. No. 11/853,194, filed Sep. 11, 2007, for PARTICLE BLAST SYSTEM WITH SYNCHRONIZED FEEDER AND PARTICLE GENERATOR, U.S. patent application Ser. No. 12/121,356, filed May 15, 2008, for PARTICLE BLASTING METHOD AND APPARATUS THEREFOR, U.S. patent application Ser. No. 12/348,645, filed Jan. 5, 2009, for BLAST NOZZLE WITH BLAST MEDIA FRAGMENTER, U.S. Patent Provisional Application Ser. No. 61/394,688 filed Oct. 19, 2010, for METHOD AND APPARATUS FOR FORMING CARBON DIOXIDE PARTICLES INTO BLOCKS, and U.S. Patent Provisional Application Ser. No. 61/487,837 filed May 19, 2011, for METHOD AND APPARATUS FOR FORMING CARBON DIOXIDE PARTICLES, are hereby incorporated by reference. 
     In a particle blast system, typically, particles, also known as blast media, are ejected by a particle acceleration device, generally referred to as a blast nozzle, and directed toward a workpiece or other target (also referred to herein as an article). Particles may be introduced into a transport gas flow through a feeder, such as is disclosed in U.S. Pat. No. 6,726,549, which is incorporated herein by reference, and transported by the transport gas, entrained therein, from the feeder to the blast nozzle through a single hose (known as a one hose system). It is also known to introduce particles into the high pressure gas at the blast nozzle, the blast nozzle being configured to combine the particle flow arriving entrained in a low volume gas flow through a first hose with high pressure gas arriving in a second hose and eject the entrained flow therefrom (known as a two hose system). 
     Various sizes are known for carbon dioxide blast media, such as pellets and granules, the selection of which is made in dependence on the blasting needs. Pellets may be formed by extruding carbon dioxide snow through a die plate. Pellet diameters come in various sizes, for example ranging from 3 mm to 12 mm. Granules may be formed by any suitable process, such as by use of the apparatus for generating carbon dioxide granules from a block, referred to as a shaver, as is disclosed in U.S. Pat. No. 5,520,572, which is incorporated herein by reference, in which a working edge, such as a knife edge, is urged against and moved across a block of carbon dioxide. As shown in the &#39;572 patent, the granules so generated are fed directly into the low volume gas flow, such as by Venturi induction as shown in FIG. 1 of the &#39;572 patent, transported by the first hose to the blast nozzle 102 (&#39;572, FIG. 6) where it is combined with the high pressure gas and directed toward a workpiece. 
     Unwanted sublimation of the carbon dioxide blast media occurs prior to the media reaching the workpiece whenever the environmental conditions allow. Sublimation of granules can be a significant problem, due at least in part to the very small mass of each individual granule relative to its volume and surface area. For example, the &#39;572 patent teaches to deliver the granules, generated by shaving a dry ice block, directly into the first hose of the two hose system with substantially no storage of the granules to be transported to be combined with the high pressure gas. 
     Until the present invention, due to sublimation, systems utilizing granules were limited to low flow apparatuses. Double hose and single hose granule systems were known, but high flow systems were not. Two hose systems using granular blast media were typically limited to low flow, with a maximum hose (for transporting granules) internal diameter of ¾″ and maximum length of 50 feet. Previously, persons of greater than ordinary skill in the art designed such systems to avoid high volume gas flow based on the conclusion that the sublimation rate of granules was proportional to the volume of the flow of gas in which the granules were entrained, leading to prior art systems maintaining low flow through small hose diameters for hoses. Attempts at using large diameter hoses in single hose systems resulted in systems with sublimation rates that required granular media flow rates of 10 to 20 lbs per minute just to equal the results of the two hose systems delivering 5 lbs per minute. Such result reinforced the continued use of smaller hose diameters. 
     The present inventors have overcome the problems unsolved by such persons of more than ordinary skill in the art, and successfully configured a single hose granular blast media system capable of delivering high flow, based on their determination that the sublimation problem was not the result of the volume of the gas flow that entrained the granules, but rather was the result of the velocity of the gas flow in which the particles were entrained. The inventors have determined that it is the difference between the speed of the gas flow and the speed of the granules that results in sublimation: The greater the difference the greater the sublimation. Applying the inventors&#39; discovery to the prior art attempts at single hose granular blast media systems, it is now to be understood that the increase in sublimation that accompanied use of a larger cross sectional area hose (i.e., the larger diameter hose), which was misinterpreted by those of more than ordinary skill in the art as resulting from increased flow volume, was the result of increased gas velocity resulting from use of nozzles which that increased the gas speed in the hose (instead of decreasing gas speed which, with increased cross sectional area, would be expected to decrease speed). However, the inventors&#39; present invention overcomes the misunderstandings, misinterpretations and shortcomings of the prior art by providing a single hose granular blast media system with high flow configured to maintain the speed differential between the transport gas and the entrained granules low enough to keep sublimation rates low enough to be functionally acceptable. 
     Although the present invention will be described herein in connection with a particle feeder for use with carbon dioxide blasting, it will be understood that the present invention is not limited in use or application to carbon dioxide blasting. The teachings of the present invention may be used in applications using particles of any sublimeable and/or cryogenic material. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention, and, together with the general description of the invention given above, and the detailed description of the embodiments given below, serve to explain the principles of the present invention. 
         FIG. 1  is a perspective view of a particle blast apparatus constructed in accordance with teachings of the present invention. 
         FIG. 2  is perspective view of the particle blast apparatus of  FIG. 1 , with the covers omitted. 
         FIG. 3  is a perspective view from the upper left front illustrating the particle generator and feeder assembly of the particle blast apparatus of  FIG. 1 . 
         FIG. 4  is a perspective view from the lower right front illustrating the particle generator and feeder assembly of the particle blast apparatus of  FIG. 1 . 
         FIG. 5  is a side cross-sectional view taken along the midline of the particle generator and feeder assembly of the particle blast apparatus of  FIG. 1 . 
         FIG. 6  is front cross-sectional view taken along the midline of the particle generator and feeder assembly of the particle blast apparatus of  FIG. 1 . 
         FIG. 7  is a perspective view of the rotatable carrier and housing of the particle generator of the particle blast apparatus of  FIG. 1 . 
         FIG. 8  is an exploded view of the rotatable carrier of  FIG. 7 . 
         FIG. 9  is a perspective cross-sectional view of a blade and adjustable slide of the rotatable carrier of  FIG. 7 . 
         FIGS. 10A, 10B and 10C  are side, perspective and end views of a blade of the rotatable carrier of  FIG. 7 . 
         FIG. 11  is a perspective view of the inner adjustable slide of the rotatable carrier of  FIG. 7 . 
         FIG. 12  is a perspective view of the outer adjustable slide of the rotatable carrier of  FIG. 7 . 
         FIG. 13  is an exploded perspective view of the feeder assembly of the particle blast apparatus of  FIG. 1 . 
         FIG. 14A  is a perspective view of the lower seal of the feeder assembly of  FIG. 13 . 
         FIG. 14B  is a top view of the lower seal of the feeder assembly of  FIG. 13 . 
         FIG. 15  is a cross-sectional view of the feeder assembly of the particle blast apparatus of  FIG. 1 . 
         FIG. 16  is a perspective view from the left front of a particle blast apparatus constructed in accordance with teachings of the present invention. 
         FIG. 17  is a perspective view of the particle blast apparatus of  FIG. 16  from the left rear. 
         FIG. 18  is a perspective view from the left front illustrating the supply bin of the particle blast apparatus of  FIG. 16 . 
         FIG. 19  is a perspective view similar to  FIG. 18 , with the door in the lower position. 
         FIG. 20  is an perspective view similar to  FIG. 5  with the linear actuator, pressure plate and rear cover exploded from the rest of the particle generator and feeder assembly. 
         FIG. 21  is perspective view from the right front illustrating the particle generator and feeder assembly with the door omitted. 
         FIG. 22  is a cross-sectional view taken along line  22 - 22  of  FIG. 21 . 
         FIG. 23  is an exploded view of the driven element and the rotatable carrier. 
         FIG. 24  is a plan view of the outer surface of the rotatable carrier of the particle generator of the particle blast apparatus of  FIG. 16 . 
         FIG. 25  a plan view of the inner surface of the rotatable carrier of the particle generator of the particle blast apparatus of  FIG. 16 . 
         FIG. 26  is a perspective view of the rotatable carrier in partial cross section. 
         FIG. 27  is a perspective view of the rotatable carrier in partial cross section. 
         FIG. 28  is an exploded view illustrating the rotatable carrier, working edges and slides. 
         FIG. 29  is an exploded view illustrating a slide of the rotatable carrier. 
         FIG. 30  is a cross-sectional view taken along line  30 - 30  of  FIG. 25 . 
         FIG. 31  is a cross-sectional perspective view similar to  FIG. 30  illustrating the over center adjustment mechanism of the adjustable slide of the rotatable carrier. 
         FIG. 32  is a fragmentary perspective view of a working edge of the rotatable carrier and a cross-sectional view taken along line  32 - 32  of  FIG. 25 . 
         FIG. 33  is an exploded perspective view of the feeder assembly of the particle blast apparatus of  FIG. 16 . 
         FIG. 34  is a cross-sectional perspective of the inlet fitting which attaches to the feeder block shown in  FIG. 33 . 
         FIG. 35  is a bottom perspective view of the lower seal of the feeder assembly of  FIG. 33 . 
         FIG. 36  is a top view of the lower seal of the feeder assembly of  FIG. 33 . 
         FIG. 37  is a perspective view of the particle generator and feeder assembly taken from the left with the feeder assembly shown in cross section. 
         FIG. 38  is a cross-sectional perspective view of the feeder assembly of the particle blast apparatus of  FIG. 16 . 
         FIG. 39  is a fragmentary perspective view of an alternative movable insert received in an rotatable carrier disposed in an open position; 
         FIG. 40  is a fragmentary cross-sectional perspective view taken along line  40 - 40  of  FIG. 39 ; 
         FIG. 41  is a fragmentary cross-sectional side view of the insert taken along line  40 - 40  of  FIG. 39  with the lever of the insert in a rotated position that permits the adjustment of the insert between open and closed positions; 
         FIG. 42  is a fragmentary perspective view of the insert of  FIG. 39  in a closed position; and 
         FIG. 43  is a cross-sectional view taken along line  43 - 43  of  FIG. 42 . 
     
    
    
     Reference will now be made in detail to an embodiment of the invention, an example of which is illustrated in the accompanying drawings. 
     DESCRIPTION 
     In the following description, like reference characters designate like or corresponding parts throughout the several views. Also, in the following description, it is to be understood that terms such as front, back, inside, outside, and the like are words of convenience and are not to be construed as limiting terms. Terminology used in this patent is not meant to be limiting insofar as devices described herein, or portions thereof, may be attached or utilized in other orientations. Referring in more detail to the drawings, an embodiment of the invention will now be described. 
     Double Motor Embodiment 
       FIGS. 1 and 2  show perspective views of a particle blast apparatus constructed in accordance with teachings of the present invention. Particle blast apparatus, generally indicated at  2 , includes frame  4  which carries and supports the individual components of the blaster, as will be described below. Control panel  6  is located at the front of particle blast apparatus  2  to control the device through a series of valves, switches, and timers. The valves, switches, timers, and controls that can be pneumatic, electric, or any combination thereof. 
     Referring to  FIG. 3 , there is shown a perspective view of particle generator, generally indicated at  8 , duct  10  and feeder assembly  12 . Particle generator  8  is disposed adjacent storage bin  14 . Bin  14  is configured to receive a block of solid carbon dioxide, such as a standard size commercially available block of dry ice, e.g., 10″×10″×12″, or to receive preformed pellets. Pressure plate  16  is longitudinally movable within bin  14 , toward and away from particle generator  8 . Pressure plate  16  may, as depicted in  FIG. 3 , include lining  18  made of a material suitable for contacting the solid material disposed in bin  14 , such as UHMW plastic. Pressure plate  16  is configured to urge any material, whether a block or a plurality of individual pellets, disposed within bin  14 , toward particle generator  8  so as to cause such material to remain in contact with particle generator  8  with sufficient force for particle generator to generate particles for introduction into the transport gas flow. Pressure plate  16  may be resiliently biased toward particle generator  8  and/or may be connected to actuator  19  to move pressure plate  16  toward and away from particle generator  8 . In the embodiment depicted, actuator  19  is a linear actuator and includes carriage  19   a  which is connected to pressure plate  16  by arm  19   b  (see  FIG. 5 ) extending from carriage. Spaced apart sides  20  of bin  14  are made of any suitable material, preferably which resists the material disposed within bin  14  from sticking to sides  20 . Hinged lid  22  overlies bin  14  to facilitate filling bin  14  with material, such as dry ice. Additionally, apparatus  2  includes rear door  23  which may be opened by pivoting about a hinge, horizontal in the embodiment depicted. Pressure plate  16  may be moved out of the way to allow solid material, such a block, to be loaded into storage bin  14  from the rear. 
     Referring also to  FIGS. 5-8 , particle generator  8  includes housing  24  to which cover  26  is attached to out facing surface  24   a  of housing  24 . Particle generator  8  includes rotatable carrier  28  which carries one or more working edges  30  and respective slides  32 . Carrier  28  moves relative to bin  14  with the material disposed in bin  14  being urged against inner surface  28   b  of carrier  28 . Carrier  28  is connected to rotor  34  by a plurality of fasteners  36 , with a plurality of spacers  38  which establish space between surface  28   a  of carrier  28  and rotor  34  through which the generated particles may fall. In the embodiment depicted, rotor  34  has a plurality of holes  34   a  in order to reduce the weight of rotor  34 . Rotor  34  also includes hub  34   b  which carries the inner races of bearings  40  that rotatably support rotor  34 . The outer races of bearings  40  are supported by frame  42 , which is in turn supported by housing  24 . Thus, through bearings  40  and hub  34   b,  rotor  34  is rotably supported by frame  42 . 
     Hub  34   b  also carries driven element  44 , which is non-rotatably fixed to hub  34   b.  Motor  46  is carried by apparatus  2 , with drive element  48  secured to the output of motor  46 . Belt  50  engages drive element  48  and driven element  44  to provide the rotation of hub  34  and thereby rotate carrier  28 . 
     Housing  24  is secured to bin  14 , with inner surface  24   b  abutting bin  14 . With cover  26  in place (not illustrated in  FIG. 5 ), collector chamber  52  is defined such that particles passing through openings  54  of rotatable carrier  28  flow into and through collector chamber  52 . Particles generated above hub  34  can fall though the space between hub  34  and carrier  28  created by spacers  38 . Particles fall through collector chamber  52  into duct  10  passing therethrough and out duct exit  10   a  directly to feeder assembly  12 . With cover  10   b  in place, duct  10  defines internal passageway  10   c  that places collector chamber  52  in fluid communication with feeder assembly feeder  12 . 
     Referring to  FIGS. 7-9 , rotatable carrier  28  includes a plurality of respective openings  54  defined between respective pairs of spaced working edges  30  and slides  32   a ,  32   b.  Pairs of working edges  30  and slides  32   a  are disposed in a first plurality of respective inner recesses  56   a ,  56   b  formed at the inner portion of rotatable carrier  28 , and pairs of working edges  30  and slides  32   b  in a second plurality of respective outer recesses  58   a,    58   b . As seen in  FIGS. 9, 10A, 10B and 10C , working edge  30  includes elongated raised cutting edge  30   a  which is disposed facing slides  32   b . Working edge  30  includes a plurality of openings  30   b  into which fasteners  60  are disposed to secure working edge  30  in recess  58   a . Any suitable opening  30   b  and fastener  60  may be used, which in the depicted embodiment are closely confirming to each other so as to hold working edge  30  in a single location (subject to tolerance). Referring also to  FIG. 12 , outer slide  32   b  includes elongated surface  32   c  which is disposed opposite cutting edge  30   a . Slide  32   b  includes a plurality of openings into which fasteners  60  as disposed to secure slide  32   b  in recess  58   b . As seen in  FIG. 11 , slide  32   a  has a similar construction as slide  32   b , it being noted that the differences between the inner and outer slides arises from the geometry of openings  56   a / 56   b  and  58   a / 58   b.    
     Slide  32   b  is configured to be disposed at a first position as seen in  FIG. 9 , at which the width of opening  54  is at its largest, and a second position at which the width of opening  54  is at its smallest. It is within the scope of this invention for slide  32   b  to be disposed at a plurality of positions between the first and second positions, whether configured as indexed positions or infinite positions. Such range of positions is accomplished through the mount configuration, which in the embodiment depicted encompasses openings  62  being configured as elongated slots into which fasteners  60  are disposed to secure slide  32   b  positionably within outer recess  58   b . Slide  32   a  is similarly configured to be positionable. 
     When slide  32   a  or  32   b  is in the first position, at which opening  54  is at its largest, larger particles may pass through the larger gap. This allows pellets to pass through opening  54  as rotatable carriage  28  is rotated, permitting pellets to be used, disposed in storage bin  14  and transported to feeder assembly  12 . Pellets being dispensed may also be reduced in size as they pass between working edges and spacers. 
     For blocks of solid material, slides  32   a ,  32   b  are disposed in the second position, at which opening  54  is at its smallest. Moving working edges  30  engage the block disposed in bin  14 , with the relative motion causing particles to be generated (created), whether by shaving the block. Small particles could also be generated from pellets when slides  32   a ,  32   b  are in the second position. 
     Referring to  FIGS. 13, 14A and 14B , feeder assembly  12  includes feeder block  64  in which inlet  66  and outlet  68  are formed. Feeder block  64  includes cavity  70  defined by wall  70   a  and bottom  70   b . Feeder block  64  is secured to plate  72  which may be secured to the frame of apparatus  2 . A pair of spaced apart bearing supports  74 ,  76  respectively carry axially aligned sealed bearings  78 ,  80 . 
     Rotor  82  may be from any suitable material and is depicted as a cylinder, although various other shapes, such as frustoconical may be used. Threaded hole  82   a  is formed in the end of rotor  82 . Rotor  82  includes peripheral surface  84  in which a plurality of spaced apart pockets  86  are formed. In the embodiment shown, there are four circumferential rows of pockets  86 , with each circumferential row having six pockets  86 . Pockets  86  are also aligned in axial rows, with each axial row having two pockets  86 . The axial and circumferential rows are arranged such that the axial and circumferential widths of pockets  86  overlap, but do not intersect, each other. 
     In this embodiment, rotor  86  is rotatably carried by bearings  78 ,  80 , for rotation by motor  88  (see  FIGS. 2-4 ). Drive member  90  is connected to rotor  86  and is driven via drive element  92 , which is driven by drive member  94  carried by motor  88 . Thrust bearing plate  96  and retaining plate  98  are disposed at one end. Thrust bearing plate  96  may be made of any suitable material, such as UHMW plastic. Rotor hub  82   b  extends through opening  100  of thrust bearing plate  96  and retaining plate  98 , engaging retainer bearing disc  102  which is backed by retainer  104  by fastener  106  extending therethrough, threadingly engaging threaded hole  82   a  so as to retain rotor  86 . The fit between bearings  74 ,  76  and rotor  82  allows rotor  82  to be easily withdrawn from feeder assembly  12  by unscrewing fastener  106  and sliding rotor out through bearing  76 . 
     Lower seal pad  108  is disposed partially in cavity  70 , with seal  110 , located in groove  112 , sealingly engaging groove  112  and wall  70   a . Lower seal pad  108  includes surface  114  which, when assembled, contacts peripheral surface  84  of rotor  82 , forming a seal therewith, as described below. Brackets  116  are attached to block  64  by fasteners (not shown), and have portions  116   a  which overly the upper surface of lower seal  108  so as to retain lower seal  108  to block  64 . As used herein, “pad” is not used as limiting: “Seal pad” refers to any component which forms a seal. 
     Upper seal pad  118  includes surface  120  which, when assembled, contacts peripheral surface  84  of rotor  82 . Fasteners  122  are disposed through holes in upper seal pad  118  to hold it in place, without significant force being exerted by surface  120  on rotor  82 . 
     Upper seal pad  118  and lower seal pad  108  may be made of any suitable material, such as a UHMW material. The ends of surfaces  114  and  120  adjacent bearing  80  may be chamfered to allow easier insertion of rotor  82   
     Referring also to  FIG. 15 , lower pad seal  108  is shown disposed in cavity  70 , with seal  110  engaging wall  70   a , and upper pad seal  118  overlying but not engaging lower pad seal  108 , surface  120  engaging rotor  82 . Surface  114  includes two openings  124  which are in fluid communication with inlet  66  through upstream chamber  128 , and two openings  126  which are in fluid communication with outlet  68  through downstream chamber  130 . It is noted that although two openings  124  and two openings  126  are present in the illustrated embodiment, the number of openings  124  and openings  126  may vary, depending on the design of feeder assembly  12 . For example, a single opening may be used for each. Additionally, more than two openings may be used for each. 
     Feeder assembly  12  has a transport gas flowpath from inlet  66  to outlet  68 . In the depicted embodiment, passageways  132  and  134  are formed in feeder block  64 . Lower seal pad  108  includes recess  136 , which is aligned with inlet  66  and together with passageway  132 , places upstream chamber  128  in fluid communication with inlet  66 . Lower seal pad  108  also includes recess  138 , which is aligned with outlet  68  and together with passageway  134 , places downstream chamber  130  in fluid communication with outlet  68 . 
     Upstream chamber  128  is separated from downstream chamber  130  by wall  140  which extends transversely across lower seal pad  108 . Lower surface  140   a  of wall  140  seals against bottom  70   b  of cavity  70 , keeping upstream chamber  128  separate from downstream chamber  130 . Wall  142  is disposed perpendicular to wall  140 , with lower surface  140   a  engaging bottom  70   b.    
     As illustrated, in the depicted embodiment, inlet  66  in fluid communication with outlet  68  substantially only through individual pockets  86  as they are cyclically disposed by rotation of rotor  82  between a first position at which an individual pocket first spans openings  124  and  126  and a second position at which the individual pocket last spans openings  124  and  126 . This configuration directs substantially all of the transport gas entering  66  to pass through pockets  86 , which pushes the blast media out of pockets  86 , to become entrained in the transport gas flow. Turbulent flow occurs in downstream chamber  130 , promoting mixing of media with the transport gas. Such mixing of the media entrains the media in the transport gas, minimizing impacts between the media and the feeder components downstream of the pockets. The significant flow of the transport gas through each pocket  86  acts to effectively clean all media from each pocket  86 . 
     It is noted that there is a gap above top  140   b  of wall  140  and top  142   b  of wall  142  and peripheral surface  84  of rotor  82 . Some transport gas flows across tops  140   b  and  142   b  from upstream chamber  128  to downstream chamber  130 . 
     Particles generated by action of working edges  30  across a block or a plurality of pellets disposed in storage bin  14 , or particles passed through openings  54 , travel directly through collector chamber  52  and internal passageway  10   c  into feeder assembly  12 . The speeds of motor  46  and motor  88  are controlled such that the displaced volumetric rate of pockets  86  is greater than the particle capacity of rotatable carrier  28  and associated parts at maximum speed. Thus, such particles reach feeder assembly  12  without being held or stored for any appreciable time period. 
     Single Motor Embodiment 
       FIGS. 16 and 17  show perspective views of a particle blast apparatus constructed in accordance with teachings of the present invention. Particle blast apparatus, generally indicated at  521 , includes frame  541  which carries and supports the individual components, as will be described below. Control panel  561  is located at the rear of particle blast apparatus  521  for use by the user to control the particle blast apparatus through a valves, switches, and timers. The valves, switches, timers, and controls can be pneumatic, electric, or any combination thereof. 
     Referring to  FIGS. 18-20 , there is shown a perspective view of the assembly including supply bin  581 , particle generator  510  and feeder assembly  512 . Bin  581  is configured to receive a block of solid carbon dioxide of any suitable size, particularly but not limited to standard commercially available blocks of dry ice, e.g., 10″ ×10″ ×12″, or to receive loose particles such as preformed pellets. Loose particles may be loaded into supply bin  581  through top opening  514 , which in the embodiment depicted may include shroud  516  surrounding opening  514  and extending upwardly aligned with opening  518 , which may be selectively covered or uncovered by lid  520 . A block of solid carbon dioxide may be loaded into supply bin  8  through top opening  514 , or loaded through side opening  522 . 
     Movable door assembly  524  may be disposed at a first position at which side opening  522  is covered, functioning to retain solid carbon dioxide, whether loose particles or a solid block, within supply bin  581 , forming a side thereof. Movable door assembly  524  is movable to a second position at which sufficient access to side opening  522  exists to load carbon dioxide into supply bin  581 . It is noted that loose particles of carbon dioxide could be loaded through side opening  522 , with an appropriate configuration of movable door assembly  524 . 
     In the depicted embodiment, movable door assembly  524  includes inner door  526  which is hingedly connected to supply bin  581  to rotate about a horizontal axis from the vertical position, essentially forming a wall of supply bin  581 , to the horizontal position, forming a shelf on which a block of dry ice could be supported and then slide into supply bin  581 . Movable door assembly  524  includes outer door  528  carried by and spaced apart from inner door  526  by spacer  530  which is secured to inner door  526 . Outer door  528  may thus be aligned with the outer skin  532  of particle blast apparatus  521 . This configuration of movable door assembly  524  cooperates with the complementary shaped opening in skin  532  to accommodate the fact that outer door  528  pivots about an offset axis, not about its lower edge, thereby producing rotation and translation. Thus the lower edge of outer door  528  is lower than the pivot axis, approximately by the distance between outer door  528  and inner door  526  defined by spacer  530 , causing the lower edge of outer door  528  to move inside of outer skin  532  as movable door assembly is rotated. Of course, any suitable configuration may be used to accomplish the function of movable door assembly. 
     Latch  534  may be included to hold movable door assembly  524  in the vertical position. Support arms  536   a  and  536   b  extend between movable door assembly  524  and frame  541  (not seen in  FIGS. 19-21 ) to support movable door assembly  524  in the horizontal position. Although support arms  536   a  and  536   b  are depicted as respective folding assemblies pivoting about each member&#39;s ends, support arms  536   a  and  536   b  may have any suitable configuration, such as retractable or non-retractable cables. 
     The rear wall of supply bin  581  is defined by moveable pressure plate  538 , which is configured to urge any material, whether a block or a plurality of individual particles, disposed within supply bin  581 , toward rotatable carrier  540  of particle generator  510  so as to cause such material to remain in contact with rotatable carrier  540  with sufficient force for particle generator to generate particles for introduction into the transport gas flow, as described below. Pressure plate  538  may be resiliently biased toward rotatable carrier  540  and/or may be actively urged and moved there towards, and may, as depicted, include a plurality of projections  538   b . Actuator  542  may be disposed adjacent supply bin  581 , and configured to move pressure plate  538  toward and away from rotatable carrier  540  of particle generator  510 . In the embodiment depicted, actuator  542  is a linear actuator and includes carriage  544  which is connected to pressure plate  538  by arm  546  extending from carriage  544 . Non-moving member  548  may be provided, in the embodiment depicted attached to actuator  542 . 
     Excluding rotatable carrier  540 , the spaced apart interior surfaces of supply bin  581  may be made of any suitable material, preferably which resists the material disposed within bin  581  from sticking to sides  520 . Inner door  526  includes liner  526   a , and pressure plate  538  includes liner  538   a , which may be made of UHMW plastic. Liner  538   a  as depicted includes a plurality of openings through which projections  538   b  extend. Similarly, bottom  550  may be a liner made of UHMW. Other suitable materials, such as smooth stainless steel may be used. 
     It is noted that the configuration of supply bin  581  is not limited to the embodiment depicted, and may have any configuration suitable to present a supply of media to particle generator  510 . For example, supply bin  581  may be configured without sides, suitable for use with a preformed block of carbon dioxide. 
     Referring also to  FIGS. 21-23 , particle generator  510  includes housing  552  which is secured to supply bin  581 . Housing  552  includes front upper cover  554 , rear upper cover  556  and rear side covers  558  and  560 , which collectively define collector chamber  562 . Housing  552  includes lower front cover  564 , which collectively define duct  566  which defines internal passageway  568  which places collector chamber  562  in fluid communication with feeder assembly  512 . Particles passing through openings (as described below) of rotatable carrier  540  flow into and through collector chamber  562 , and into and through internal passageway  568  and to feeder assembly  512 . 
     Rotatable carrier  540  is movable, and in operation moves, relative to supply bin  581  with the material disposed in supply bin  581  being urged against inner surface  540   a  of rotatable carrier  540 . The rotation of rotatable carrier  540  results in the generation (or feeding) of particles into collector chamber  562 . Therefore, the rate of rotation of rotatable carrier  540  determines the rate at which particles are generated (or fed) into collector chamber  562  into internal passage way  568  and to feeder assembly  512 . Rotatable carrier  540  is connected to rotor  570  by a plurality of fasteners  574 , with a plurality of spacers  576  establishing space between surface  540   a  of rotatable carrier  540  and rotor  570  through which the generated particles may fall. In the embodiment depicted, rotor  570  has a plurality of holes  570   a  in order to reduce the weight of rotor  570 . Rotor  570  also includes hub  572  which carries the inner races of bearings  578  that rotatably support rotor  570 . The outer races of bearings  578  are supported by bearing block  580  which is secured to cover  552  by a plurality of fasteners  582 . 
     Hub  572  also carries driven element  584 , which is non-rotatably fixed to hub  572 . Drive element  586  drives driven element  584  through endless drive element  588 , which is configured complementarily with driven element  584  and drive element  586 . In the embodiment depicted, driven element  584  and drive element  586  are depicted as toothed elements, such as sprockets, with endless drive element  588  being a toothed belt or chain. Thus the rotation of driven element  584  is synchronized with the rotation of drive element  586 . Since the rotation of rotatable carrier  540  is synchronized with the rotation of driven element  584  (in the embodiment depicted 1:1) and since, as described below, the rotation of drive element  586  is synchronized with the rotation of the feeder rotor of feeder assembly  512 , the rate at which particles are generated is synchronized with the rotational rate of the feeder rotor. 
     Referring to  FIGS. 24-28 , rotatable carrier  540  includes a plurality of fixed openings  590  and adjustable openings  592 . Also referring to  FIG. 32 , in the embodiment depicted, a plurality of fixed inserts  594  are disposed in respective recessed openings  596 . The configuration of each recessed opening includes recessed portion  596   a  in surface  540   a  of rotatable carrier  540 , recessed slot  596   b  diverging in the direction from surface  540   a  to  540   b  of rotatable carrier  540 , and edge  596   c . Each fixed insert  594  has working edge  598 , with fixed openings  590  being the gaps defined between edges  596   c  of recessed openings  596  and working edges  598 . Inserts  594  are secured to rotatable carrier  540  by a plurality of fasteners  600 . Working edges  598  are configured to generate particles, such as granules, through a shaving action by moving across an adjacent face of a block of carbon dioxide being urged against inner surface  540   a  of rotatable carrier  540 . In the embodiment depicted, working edges  598  are configured as knife edges extending above inner surface  540   a . The size and amount of particles being generated by the shaving action is a function of the configuration of working edges  598  and fixed openings  590 . The rate of the relative motion between working edges  598  and the adjacent face of the dry ice block determines the rate at which particles are generated for a particular working edge/fixed opening configuration. 
     In the embodiment depicted, an inner plurality of fixed openings  590  extending generally radially outward from the center of rotatable carrier  540 . An outer plurality of fixed openings  590  is disposed spaced from the center of rotatable carrier  540  oriented non-radially. In the embodiment depicted, the outer plurality of fixed openings  590  appear oriented generally perpendicular to respective ones of the inner plurality of fixed openings  590 . Any suitable configuration, e.g., location and orientation, of fixed openings  590  may be used. Additionally, although not shown in these figures, fixed inserts  594  could be configured to be movable to define non-fixed openings, with working edges  598  functioning to shave. 
     Referring also to  FIGS. 29-31 , a plurality of movable inserts  602 , also referred to herein as slides  602 , are disposed in respective recessed openings  604 . Each slide  602  has a generally T shaped configuration with arm portions  606   a  and  606   b  extending outwardly from central portion  608  generally perpendicularly therefrom. Recessed openings  604  include recessed central portion  610  and recessed arm portion  612  and  614 . Recessed arm portion  612  includes tip  612   a  and recessed arm portion  614  includes recessed tip  614   a.    
     Edges  616  define a fixed boundary of openings  592 , with movable edges  606   c  of slides  602  defining the other boundary. Formed in edges  606   c  are recesses  606   d , which provide a surface spaced apart from edges  616  when edges  606   c  are proximal edges  616 . 
     Recessed arm portions  612  and  614  are depicted as having the same thickness of arm portions  606   a  and  606   b , while the overall width is greater than the width of opening  592  with the distal ends of arm portions  606   a  and  606   b  overlying tips  612   a  and  614   a  respectively, providing support therefor. 
     Central portion  608  is thicker than arm portions  606   a  and  606   b , as seen at  608   a.  Recessed central portion  610  of recessed opening  604  is shaped complementarily to central portion  608  although deeper than the thickness of central portion  608 , and including elongated slot  618 . Disposed within recessed central portion  610  is complementarily shaped stem portion insert  620 , having elongated slot  620   a  defined by wall  620   b  which extends into elongated slot  618 . Insert  620  may be made of any suitable material, such as UHMW. 
     Opening  604  includes inclined surface  622  extending divergingly in the direction toward outer surface  540   b.    
     Central portion  608  includes recess  624  configured to receive rotatable over-center lever  626 . Lever  626  includes head portion  628  and arm  630 . Head portion  628  is pivotably connected to retaining member  632  by pin  634  extending through hole  636  in head portion  628  and hole  638  depicted as disposed generally on the axis of retaining member  632 . Head portion is also pivotably connected to central portion  608  by two pins  640   a  and  640   b  extending through respective holes  642   a  and  642   b  of central portion  608  and into holes  644   a  and  644   b  of head portion  628 . 
     Retaining member  632  is threaded at its end distal over center lever  626  and extends through slot  618  beyond outer surface  540   b  of rotatable carrier  540 . A plurality of spring washers  644  disposed between bearing washers  646  and nut  648 . To prevent nut  648  from rotating, cotter pin  650  is used. Over center lever is thus resiliently biased in the direction from inner surface  540   a  toward outer surface  540   b  by retaining member  632 . Holes  644   a  and  644   b  are offset relative to holes  636  and  638 , producing an over-center construction. Slide  602  may be moved within recessed opening between the fully open position illustrated in  FIG. 31 , whereat opening  592  is at its maximum size to the closed position with edge  616  adjacent edge  606   c , whereat  592  is at its minimum, which is fully closed in the embodiment depicted. 
     In one mode, openings  592  may be set at their minimums when a block of solid carbon dioxide is disposed in supply bin  581  and working edges  598  are shaving particles from the adjacent face. In another mode, when loose particles, such as pellets, are disposed in supply bin  581 , openings  592  may be set between and up to its minimum and maximum size to meter the loose particles to feeder assembly  512 . The size of openings  592  as well as the rotational speed of rotatable carrier  540  determine the flow rate of particles. At any given rotational speed, the larger the openings  592  the higher the flow rate of particles. 
     Referring to  FIGS. 33-38 , feeder assembly  512  includes feeder block  652  in which inlet  654  and outlet  656  are formed. Inlet  654  includes inlet fitting  202 . Feeder block  652  includes cavity  658  defined by wall  658   a  and bottom  658   b . Feeder block  652  is secured to plate  660  which may be secured to the frame of apparatus  521 . A pair of spaced apart supports  662  and  664  are secured to feeder block  652 . Sealed bearing  666  is carried by support  662 . 
     Rotor  668  may be from any suitable material and is depicted as a cylinder, although various other shapes, such as frustoconical may be used. Shaft  670  extends from rotor  668 , with drive element  586  disposed thereon. Rotor  668  includes peripheral surface  672  in which a plurality of spaced apart pockets  674  are formed. In the embodiment shown, there are four circumferential rows of pockets  674 , with each circumferential row having six pockets  674 . Pockets  674  are also aligned in axial rows, with each axial row having two pockets  674 . The axial and circumferential rows are arranged such that the axial and circumferential widths of pockets  674  overlap, but do not intersect, each other. 
     In this embodiment, rotor  668  includes legs  676  which are engaged by legs  678  of coupling  680 . Coupling  680  may be secured to motor  682  such that rotor  668  may be driven by motor  682 , thereby driving drive element  586 , which in turn drives driven element  584  through endless drive element  588 . In this configuration, when properly aligned, rotor  668  does not experience significant axial loading. Retaining plates  684  and  686  are disposed at one end of rotor  668 , and may be made of any suitable material, such as UHMW plastic. The fit between bearing  666  and rotor  668  allows rotor  668  to be easily withdrawn from feeder assembly  512  by removing retaining plates  684  and  686 , sliding rotor  668  out through bearing  666 . 
     Lower seal pad  688  is disposed partially in cavity  658 , with seal  690  located in groove  692 , sealingly engaging groove  692  and wall  658   a . Lower seal pad  688  includes surface  694  which, when assembled, contacts peripheral surface  672  of rotor  668 , forming a seal therewith, as described below. Bracket  696  is attached to block  652  by fasteners (not shown), and has portion  696   a  which overlies the upper surface of lower seal  688  so as to retain lower seal  688  to block  652 . As used herein, “pad” is not used as limiting: “Seal pad” refers to any component which forms a seal. 
     Upper seal pad  698  includes surface  200  which, when assembled, contacts peripheral surface  672  of rotor  668 . Upper seal pad  698  and lower seal pad  688  may be made of any suitable material, such as a UHMW material. The ends of surfaces  694  and  200  may be chamfered to allow easier insertion of rotor  668 . 
     As seen in  FIG. 38 , lower pad seal  688  is disposed in cavity  658 , with seal  690  engaging wall  658   a , and upper pad seal  698  overlying but not engaging lower pad seal  688 , surface  200  engaging rotor  668 . Surface  694  includes two openings  204  which are in fluid communication with inlet  654  through upstream chamber  208 , and two openings  206  which are in fluid communication with outlet  656  through downstream chamber  210 . It is noted that although two openings  204  and two openings  206  are present in the illustrated embodiment, the number of openings  204  and openings  206  may vary, depending on the design of feeder assembly  512 . For example, a single opening may be used for each. Additionally, more than two openings may be used for each. 
     Feeder assembly  512  has a transport gas flowpath from inlet  654  to outlet  656 . In the depicted embodiment, passageways  212  and  214  are formed in feeder block  652 . Lower seal pad  688  includes recess  216 , which is aligned with inlet  654  and together with passageway  212 , places upstream chamber  208  in fluid communication with inlet  654 . Lower seal pad  688  also includes recess  218 , which is aligned with outlet  656  and together with passageway  214 , places downstream chamber  210  in fluid communication with outlet  656 . 
     Upstream chamber  208  is separated from downstream chamber  210  by wall  216  which extends transversely across lower seal pad  688 . Lower surface  216   a  of wall  216  seals against bottom  658   b  of cavity  658 , keeping upstream chamber  208  separate from downstream chamber  210 . Wall  218  is disposed perpendicular to wall  216 , with lower surface  218   a  engaging bottom  658   b.    
     As illustrated, in the depicted embodiment, inlet  654  is in fluid communication with outlet  656  substantially only through individual pockets  674  as they are cyclically disposed by rotation of rotor  668  between a first position at which an individual pocket first spans openings  204  and  206  and a second position at which the individual pocket last spans openings  204  and  206 . This configuration directs substantially all of the transport gas entering inlet  654  to pass through pockets  674 , which pushes the blast media out of pockets  674 , to become entrained in the transport gas flow. Turbulent flow occurs in downstream chamber  210 , promoting mixing of media with the transport gas. Such mixing of the media entrains the media in the transport gas, minimizing impacts between the media and the feeder components downstream of the pockets. The significant flow of the transport gas through each pocket  674  acts to effectively clean all media from each pocket  674 . 
     It is noted that there is a gap above top  216   b  of wall  216  and top  218   b  of wall  218  and peripheral surface  672  of rotor  668 . Some transport gas flows across tops  216   b  and  218   b  from upstream chamber  208  to downstream chamber  210 . 
     Particles generated by action of the working edges across a block or a plurality of pellets disposed in supply bin  581 , or particles passed through openings  592 , travel directly through collector chamber  562  and internal passageway  568  into feeder assembly  512 . The relative rates of rotatable carriage  540  and rotor  668  is set such that the displaced volumetric rate of pockets  574  is greater than the particle capacity of rotatable carrier  540  and associated parts at maximum speed. Thus, such particles reach feeder assembly  512  without being held or stored for any appreciable time period. 
     Alternative Slide Embodiment 
     Referring to  FIGS. 39-43 , a plurality of movable inserts  702 , also referred to herein as slides  702 , are disposed in respective recessed openings  704  which are similar to openings  604  described above. Edges  716  of recessed openings  704  define a fixed boundary of openings  592 , with movable edges  706  of slides  702  defining the other boundary. Each slide  702  has a generally T shaped configuration that is similar to slide  602  described above. 
       FIGS. 39-40  show insert  702  disposed in opening  704  in an open position, such that opening  592  is at a maximum size. As shown in  FIG. 40 , end  709  of central portion  708  is disposed above surface  715  defining recessed opening  704  and terminating at edge  717  that is spaced apart from edge  716 .  FIG. 41  shows lever  726  rotated in the direction of arrow (A) to a position from which it is possible to move insert  702  in the direction of arrow (B). As further described below, lever  726  is then rotated in the direction of arrow (C) to positively locate insert  702  with opening  604  in a closed position, as shown in  FIGS. 42-43 . In the closed position, opening  592  is closed and at its minimum size. Further, in the closed position, a portion of surface  715  is exposed as shown as surface  715   a  in  FIG. 43 . 
     As shown in  FIGS. 40, 41, and 43 , insert  702  includes pin  730  that projects from an undersurface of insert  702  and is configured to be received in one of two openings  732  or  734  in surface  715  of recessed opening  704 . When insert  702  is in an open position as shown in  FIG. 40 , a sufficient portion of pin  730  is disposed within first opening  732  so as to provide positive locating of insert  702  within opening  704  sufficient to resist movement. To adjust insert  702 , as shown in  FIG. 41 , lever  726  is rotated in the direction of arrow (A), allowing slide  702  to be moved away from surface  715  such that pin  730  is no longer disposed in first opening  732 . Insert  702  may then be moved in the direction of arrow (B) to a location at which pin  730  aligns with second opening  734 , and moved toward surface  715  causing pin  730  to be disposed within second opening  734 . Lever  726  is rotated in the direction of arrow (C) to hold slide  702  adjacent or at least sufficiently proximal surface  715  such that at least a portion of pin  730  remains disposed in second opening  734  so as to positively locate insert  702  within opening  704  sufficient to resist movement of slide  702  from the closed position as shown in  FIG. 43 . Alternately, pin  730  and first and second openings  732 ,  734 , may be replaced by a resilient detent configuration, such as with a spring and ball detent carried by slide  702  engaging shallow openings in surface  715  in place of first and second openings  732 ,  734 , sufficiently strong to retain slide  702  in the desired location. Although only open and closed positions are illustrated, it is within the scope of the present disclosure to provide one or more additional positive locating positions for slide  702  intermediate the full open and full closed positions. 
     The foregoing description of one or more embodiments of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed. Obvious modifications or variations are possible in light of the above teachings. The embodiment was chosen and described in order to best illustrate the principles of the invention and its practical application to thereby enable one of ordinary skill in the art to best utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. Although only a limited number of embodiments of the invention is explained in detail, it is to be understood that the invention is not limited in its scope to the details of construction and arrangement of components set forth in the preceding description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or carried out in various ways. Also, in describing the preferred embodiment, specific terminology was used for the sake of clarity. It is to be understood that each specific term includes all technical equivalents which operate in a similar manner to accomplish a similar purpose. It is intended that the scope of the invention be defined by the claims submitted herewith. 
     Another embodiment of the present invention is described in U.S. Provisional Patent Application Ser. No. 61/594,347, filed on Feb. 2, 2012, titled APPARATUS AND METHOD FOR HIGH FLOW PARTICLE BLASTING WITHOUT PARTICLE STORAGE, which is incorporated herein by reference and which is set forth Appendix A of this application. 
     The foregoing description has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed. Obvious modifications or variations are possible in light of the above teachings. The embodiment was chosen and described in order to illustrate the principles of the invention and its application to thereby enable one of ordinary skill in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. Although only a limited number of embodiments of the invention is explained in detail, it is to be understood that the invention is not limited in its scope to the details of construction and arrangement of components set forth in the preceding description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or carried out in various ways. Also, specific terminology was used herein for the sake of clarity. It is to be understood that each specific term includes all technical equivalents which operate in a similar manner to accomplish a similar purpose. It is intended that the scope of the invention be defined by the claims submitted herewith.