Abstract:
A process and apparatus wherein a bulk quantity of parts is positioned in a channel-like treating chamber which is subjected to vibration to cause the flowable mass of parts to slowly undergo a corkscrew-like tumbling movement. One or more nozzle arrangements are positioned adjacent the treating chamber so that each nozzle has its discharge orifice position closely adjacent the flowing bulk mass in the chamber to effect high-velocity blasting of a selected region of the flowing mass. The nozzle emits a high-velocity spray which is defined by a carrier medium such as air having small abrasive particles or grit embedded therein. The abrasive spray contacts a concentrated area which has relatively small transverse and longitudinal extent over the flowing mass in the chamber. Due to its high-velocity discharge, the spray is effective in penetrating at least partway into the depth of the flowing mass to abrade the parts.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]    This application relates to and incorporates therein, in its entirety, the subject matter of U.S.A. Provisional Application Serial No. 60/211,641 filed Jun. 14, 2000. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    This invention relates to an improved process and apparatus for finishing, and more specifically abrading, a large number of parts, substantially in bulk treatment, for removing flash, burrs, sharp corners and surface contamination.  
         BACKGROUND OF THE INVENTION  
         [0003]    A wide variety of vibratory and tumbling processes and apparatus have been developed for finishing parts, and these known arrangements for the most part are reasonably efficient in their performance on some parts, particularly larger and more durable parts. The known arrangements, however, have proven less effective when dealing with large quantities of smaller parts and specifically those of more delicate materials such as plastics or powdered metals, and in particular those parts having complex configurations.  
           [0004]    One of the most commonly used techniques for finishing parts involves a tumbling device such as an elongate barrel which rotates or moves generally about a horizontal axis, and the bulk quantity of parts is positioned in the barrel whereby they travel upwardly along one interior side of the barrel during rotation thereof, and then tumble back downwardly due to the effect of gravity. Many of these tumblers also use nozzles disposed interiorly thereof to effect blasting of the parts simultaneously with the tumbling thereof. These known arrangements, however, have been observed to be relatively violent in that the nature of the tumbling action makes it difficult to control the movement of the parts, and thus such arrangements have been observed to cause significant damage such as chipping and the like when the parts being processed are of a fragile or delicate nature.  
           [0005]    With respect to known vibratory arrangements, the parts are typically positioned in a vibratory machine having an elongate channel which contains not only the parts, but also a quantity of bulk abrasive media. Due to the vibration of the machine, the parts and bulk abrasive media function effectively as a flowable mass such that the parts and abrasive media are moved, typically in a progressive screw-like pattern along the length of the confining chamber as a result of the vibration of the apparatus. The gradual tumbling movement of the flowable mass causes the parts and abrasive media to continually rub and contact one another so as to effect surface finishing of the parts. While such vibratory arrangement is particularly desirable in that it is capable of handling and not severely damaging delicate parts, nevertheless such process is relatively slow in terms of performance time, and also requires substantial quantities of consumable abrasive media. This arrangement also is not as effective for finishing of complex shaped parts, specifically those having bores or holes therethrough due to the difficulty in effectively accessing such regions during tumbling of the flowable mass.  
           [0006]    Accordingly, it is an object of this invention to provide an improved process and apparatus for finishing, for example abrading, parts which particularly have a complex configuration or shape, and/or which may be of delicate or frangible material, with the improved process and apparatus of this invention overcoming many of the disadvantages associated with prior arrangements.  
           [0007]    More specifically, this invention relates to a process and apparatus wherein a bulk quantity of parts are positioned in a channel-like treating chamber which is subjected to vibration so as to cause the flowable mass of parts in the chamber to slowly undergo a corkscrew-like tumbling movement, whereby the parts are slowly and gently circumferentially tumbled around the transverse cross-section of the treating chamber while at the same time the flowable mass of parts is progressively moved lengthwise of the chamber. In a preferred embodiment, one or more nozzle arrangements are positioned directly over the treating chamber so that each nozzle has its discharge orifice position closely adjacent and directly above the flowing bulk mass in the chamber so as to effect a high-pressure blasting of a selected region of the flowing mass. The nozzle emits a downwardly-directed high-velocity spray which is defined by a carrier medium such as air having small abrasive particles or grit embedded therein. The abrasive spray contacts a reasonably small or concentrated area which has relatively small transverse and longitudinal extent over the flowing mass in the chamber. Due to its highvelocity discharge, the spray is effective in penetrating downwardly at least partway into the depth of the flowing mass. Accordingly, the slow corkscrew-like vibratory movement of the tumbling bulk mass causes and allows the orientation of the individual parts making up the mass to constantly change as they slowly move through the relatively small blasting zone defined below the nozzle, whereby the many different surfaces including edges and corners of the parts are thus subjected to the highvelocity abrasive spray which, in combination with the gentle tumbling contact of the parts with one another, is effective for removing flash, burrs, sharp edges, surface oxides and the like.  
           [0008]    In the improved process and apparatus of the present invention, as aforesaid, the blasting nozzle typically involves use of air as a media for effecting high-velocity discharge of solid abrasive media, and the velocity of the discharge from the blasting nozzle will normally be in the range of from about 80 to about 150 feet per second so as to achieve the desired abrading performance. In some instances, however, the carrier media for the abrasive as discharged from the blasting nozzle may comprise a liquid.  
           [0009]    In the improved apparatus and process of this invention, as aforesaid, the vibrating apparatus includes an elongate treating channel which may be either circular or arcuate and which is subject to vibration in a conventional manner so as to effect gradual and gentle corkscrew-like tumbling of the flowable mass in the lengthwise extent of the channel, and in many instances a plurality of blasting nozzles are positioned in longitudinally spaced relationship along and typically above the channel to permit subsequent treating of the flowable mass as it slowly tumbles and longitudinally advances along the channel. The sequentially positioned blasting nozzles can themselves be utilized to supply different types of blasting media so as to permit the flowable mass to be progressively abraded using different blasting media, such as finer or softer media as the flowable mass approaches its discharge time or location.  
           [0010]    With the improved process and apparatus of the present invention, by causing the abrasive media to be blasted into the slowly tumbling bulk mass of parts which slowly move into and through a small and concentrated blasting zone, the use of carrier media such as air or water as well as the higher pressure thereof necessary to effect high discharge velocity, and the quantity of solid abrasive media which is intermixed in the discharged spray, can be optimized in terms of both efficient use and overall performance, and at the same time the tumbling of the mass of bulk parts is sufficiently gentle as to minimize damage to the parts as a result of both the tumbling and blasting thereof.  
           [0011]    In the improved process and apparatus of the present invention, the blasting nozzles may be positioned at various locations relative to the elongate treating channel so as to optimize the overall treating effect. For example, while positioning the blasting nozzles above the channel will often be a preferred location, nevertheless in some situations the nozzles may be disposed so as to discharge directly into the flowable mass within the channel, such as by disposing the nozzle so that it is oriented to discharge directly through the wall of the channel, such as through a side or bottom wall of the channel. In addition, the blasting nozzle may utilize any conventional technique for introducing the abrasive into the discharged fluid stream, such as either a conventional vacuum or aspiration-type nozzle which effectively sucks the abrasive into the fluid stream, or a conventional pressure-type nozzle which effectively causes the abrasive under pressure to be injected into the discharged fluid stream. In addition, in some applications the overall finishing performance may be vastly improved by intermixing the bulk parts with a plurality of inert flowable tumbling elements such as polyurethane elements which are relatively inert when subjected to the abrasive media discharged by the blasting nozzle, whereby the flowable mass defined by the inert tumbling elements and the parts being treated thus provides increased or optimized spacing and tumbling of the parts and hence increased treating thereof by the abrasive media as the parts flow through the blasting zones.  
           [0012]    Other objects and purposes of the present invention will be apparent to persons familiar with processes and arrangements of this general type upon reading the following specification and inspecting the accompanying drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]    [0013]FIG. 1 is a perspective view of a vibratory finishing apparatus for a flowable bulk mass and having, in the illustrated arrangement, a plurality of blasting nozzles associated with the apparatus and positioned above the treating channel for effecting abrading of the mass of parts in the treating channel.  
         [0014]    [0014]FIG. 2 is a fragmentary side elevational view which diagrammatically illustrates the arrangement of FIG. 1.  
         [0015]    [0015]FIG. 3 is a top view of the apparatus wherein the cover over the treating channel has been removed for clarity of illustration.  
         [0016]    [0016]FIG. 4 is an enlarged fragmentary sectional view which illustrates the cross section of the treating channel and the disposition of a blasting nozzle thereover.  
         [0017]    [0017]FIG. 5 is an enlargement of solely the treating channel and its associated blasting nozzle, and a diagrammatic representation of the penetration of the blasting spray into the flowing mass of bulk parts.  
         [0018]    [0018]FIG. 6 is a diagrammatic perspective representation as to the tumbling corkscrew-like movement of the flowing mass of parts longitudinally along the treating channel.  
         [0019]    [0019]FIG. 7 is a diagrammatic representation similar to FIG. 5 but illustrating a modification wherein the blasting nozzle communicates directly with the flowing mass and acts through the side wall of the treating channel.  
         [0020]    [0020]FIG. 8 is a diagrammatic representation similar to FIG. 7 but illustrating a further variation wherein the blasting nozzle acts through the bottom of the channel so as to discharge the abrasive spray upwardly into the flowing mass. 
     
    
       [0021]    Certain terminology will be used in the following description for convenience and reference only, and will not be limiting. For example, the words “upwardly”, “downwardly”, “leftwardly” and “rightwardly” will refer to directions in the drawings to which reference is made. The word “forward” will also refer to the normal advancing direction of the flowing mass along the treatment channel. The words “inwardly” and “outwardly” will refer to directions toward and away from, respectively, the geometric center of the apparatus and designated parts thereof. Said terminology will include the words specifically mentioned, derivatives thereof, and words of similar import.  
       DETAILED DESCRIPTION  
       [0022]    Referring to FIGS.  1 - 6 , there is illustrated an improved finishing apparatus  11  for carrying out the improved finishing process of the present invention, which finishing of parts involves abrading of the parts to effect removal of flash, burrs, sharp corners and undesired surface features such as oxides.  
         [0023]    The apparatus  11  includes a generally upright housing  12  which, in the illustrated embodiment, is constructed generally as an upright cylinder and includes an upwardly-opening tub  13  fixed thereto in surrounding relationship therewith. The tub  13 , in the illustrated embodiment, includes annular channels  14  and  15  which extend generally concentrically of the tub in surrounding relationship to one another and open upwardly, whereby these channels accommodate therein a flowable bulk mass for effecting treating thereof as described hereinafter.  
         [0024]    The housing  12  is supported on a generally rigid frame  16  by a plurality of springs  17  which have lower ends mounted to the frame and upper ends mounted to the housing, with the plurality of springs being disposed in circumferentially spaced relationship around the central axis  22  of the housing so as to resiliently support the housing for vibratory movement generally about this axis.  
         [0025]    The housing  12  mounts thereon a vibratory device for effecting vibratory or gyratory movement of the housing due to its support by the springs  17 . The vibratory device includes a motor  18  which is mounted on the housing and acts through a drive arrangement, specifically a belt drive  19 , for effecting rotation of a shaft  21  which is rotatably supported on the housing  12  generally along the central axis  22  thereof. The rotary shaft  21  in turn mounts thereon an eccentric weight arrangement  23  which, when rotated, effects a vibratory or gyratory movement of the entire housing  12  relative to the frame  16 .  
         [0026]    The channel  15  is elongated generally along a longitudinally extending central axis  25 , with this channel and its axis in the illustrated embodiment being of a generally annular or circular configuration generated substantially about the central axis  22  of the housing. It will be appreciated, however, that the elongate channel  15  can be of an arcuate configuration which is other than circular, for example it can be spiral relative to the central axis, and in some situations the channel can be defined in a vibrator which is of a straight configuration, such being well known.  
         [0027]    The channel  15  typically has a top or mouth  26  which is open so as to allow access into the channel, with the channel itself being defined by a surface wall  27  which along at least the bottom portion of the channel preferably has a rounded concave configuration which typically resembles a semi-circle, and in the illustrated and preferred embodiment the channel  15  has a transverse cross section whereby the substantially rounded bottom wall joins to side walls which project upwardly and continue with the same curvature as the bottom wall so that a majority of the side wall of the channel is defined by a generally circular configuration which extends through an angle in excess of 180°, for example an angle of about 210° up to about 240°, with this rounded side wall configuration then joining to side wall portions which project upwardly and define the mouth of the channel. This configuration of the channel cross section, which itself is well known, facilitate the desired transverse rotary tumbling of the parts when the apparatus is vibrated, as discussed hereinafter.  
         [0028]    The side wall  25  which defines the channel area, and hence functions as a liner for the channel so as to provide protective contact with the parts being moved along the channel, is typically constructed of a molded plastics material such as polyurethane or equivalent.  
         [0029]    The overall construction of the apparatus  11  as described above is conventional and well known, and in effect constitutes a structure which is provided in vibratory tub or bowl-type part finishing devices.  
         [0030]    The apparatus  11  of the present invention mounts thereon at least one blasting nozzle arrangement  31  which, in this embodiment, is disposed directly above the treating channel  15 . The blasting nozzle arrangement  31  in the illustrated embodiment is secured to a mounting bracket  32  which in turn connects to a wall of the housing  12  which extends in surrounding relationship to the channel  15 . The nozzle arrangement  31  is oriented generally vertically so that its discharge end or orifice  33  is disposed generally at or within the upwardly opening mouth of the channel  15 , and the discharge orifice is oriented generally downwardly into the channel  15  so as to emit a generally conical spray pattern  36  onto the flowing bulk mass  37  which is disposed within and is being tumblingly advanced longitudinally along the channel. The blasting nozzle arrangement has appropriate conduits  34  and  35  connected to the body thereof so that one supplies high-pressure blasting fluid to the nozzle, and the other supplies relatively fine particulate solid abrasive (i.e. grit). The very fine or small-sized abrasive particles as supplied to the nozzle may be contained in a liquid carrier if desired, such as a slurry, so as to facilitate supply of grit to the nozzle since any liquid associated with the slurry will be readily atomized in the nozzle.  
         [0031]    The nozzle arrangement  31  is of conventional construction in that it utilizes the high pressure of the blasting fluid and, in passing through the nozzle body to the discharge opening, effects entrainment therein of the particulate blasting media, whereupon the nozzle orifice  33  thus effects downward discharge of the spray  36  which conventionally has an enlarging conical spray pattern as it moves away from the discharge orifice. The discharge spray  36  is defined by the main blasting fluid which is discharged from the nozzle  33  at a high velocity and which has entrained therein the small solid particles defining the abrasive media.  
         [0032]    In a preferred arrangement the blasting fluid comprises air, although in some situations it will be recognized that liquids such as water may be utilized as the discharge media. The fluid (i.e. air) discharged from nozzle  33  preferably will typically be discharged at a velocity in the range of from about 60 feet per second to about 280 feet per second, with the typical and normal discharge velocity range expected to be between about 80 feet per second and about 150 feet per second.  
         [0033]    As illustrated by FIG. 5, the flowing bulk mass  37  typically comprises a large quantity of small elements or parts which occupy a significant portion of the channel  15 , such as at least the lower part of the channel so that the flowing mass has an upper surface level which, as indicated at  40 , is generally positioned close to but spaced downwardly a small distance below the discharge orifice  33  of the blasting nozzle. This relationship, coupled with the high velocity of the conical discharge  36  and the looseness or porosity of the bulk mass  37 , causes the discharge spray  36  where it contacts the flowing mass  37  to be concentrated over a rather small area which extends both transversely and longitudinally of the flowing mass, but at the same time this enables the discharged spray  36  to penetrate downwardly into the flowable mass at least a significant distance toward the bottom of the channel. The individual members or parts of the flowing mass, as they move through the blasting region (i.e. volume) which is contacted and penetrated by the discharge spray  36 , thus are intimately acted upon by the high-velocity carrier containing abrasive media therein so as to effect desired abrading of the parts so as to remove burrs, flash, sharp corners and the like without effecting any significant damage to the parts.  
         [0034]    In the illustrated arrangement the housing  12  is provided with a top cover  38  which effectively encloses the top  26  of the treating channel  15 , and this cover  38  has a small opening  39  therein through which the discharge end of the nozzle arrangement  31  projects for access with the channel  15 . The cover  38  thus provides for desired confinement of the discharge spray  36  interiorly of the treating channel.  
         [0035]    The top cover  38  in turn is provided with an openable gate or hatch  41  which permits the bulk quantity of parts to be deposited into the channel  15  for subsequent abrading or treating thereof. This can be accomplished manually if desired, or alternatively the hatch or gate  41  can be controlled automatically and connected to a suitable supply chute.  
         [0036]    The arrangement  11  is also provided with a gate  42  which controls communication from the treating channel  15  to the outer channel  14 . The gate  42  is of conventional construction and controlled by a driving device such as a pressure cylinder (not shown) so that when the gate  42  is closed the channel  15  is a continuous annular track which enables the parts to be moved therearound through multiple revolutions. Opening of this gate  42 , however, diverts the parts from the channel  15  into the outer channel  14  which can be provided with appropriate nozzles or other supply devices  43  for supplying cleaning fluid or the like to the channel  14  to effect removal of abrasives and other undesirable contaminants from the parts. A deflector  44  at the end of channel  15  causes the finished parts to be deflected sidewardly to a discharge chute  45 . The channel  15  will have suitable filters, screens and the like associated therewith for effecting removal of the fluids, and abrasive solids and other contaminants can be separated from the finished parts in a conventional manner.  
         [0037]    In operation of the apparatus  11 , the vibratory or gyratory movement of the tub  13  causes the bulk part mass  37  to undergo a gentle rotary tumbling movement in a direction which is generally transverse to the lengthwise extent of the channel  15 , which transverse tumbling is significantly aided by the partial rounded cross section of the channel. Simultaneous with this transverse rotary tumbling of the parts, the flowable mass  37  is also slowly advanced in the lengthwise or longitudinal direction of the channel. The flowing mass  37  hence has a gentle tumbling movement which has a configuration which roughly corresponds to a helical or corkscrew-like movement, such being diagrammatically indicated at  46  in FIG. 6. With this arrangement, movement of the flowing bulk mass along the elongate treating channel  15  hence causes the individual parts which make up the flowable bulk mass to be tumbled in a generally circular pattern transversely of the track through numerous revolutions simultaneous with the longitudinal advancement of the mass, and hence longitudinal advancement of the individual parts, in the lengthwise extent of the track. As the gently and slowly tumbling bulk mass  36  moves into and thence through the spray zone defined below the blasting nozzle arrangement  31 , the individual parts hence are undergoing a transverse rotary tumbling movement simultaneous with a slow longitudinal advancing movement through the spray zone, and in doing so the parts are undergoing a constantly changing orientation as they move through the blasting zone, thereby providing exposure of substantially all of the part surfaces to the blasting zone as the parts tumble slowly therethrough.  
         [0038]    With the arrangement of the present invention, the treating channel can be provided with multiple blasting nozzles associated therewith at spaced intervals therealong, such being illustrated by FIG. 2 which depicts four such blasting nozzles disposed in spaced relationship along the treating channel. When using multiple blasting nozzles, this permits the overall abrading process to be finely tuned since each blasting nozzle can be utilized to provide its own unique blasting characteristic. For example, the different blasting nozzles can be provided with different blasting pressures, and/or different blasting media in terms of either material properties and/or particle size, so as to permit subsequent and optimized abrading of the parts defining the flowable bulk mass. More specifically, a first blasting nozzle as disposed more closely adjacent the upstream end of the channel may be provided so as to supply a first type of abrasive media entrained within the carrier fluid discharged into the flowing mass of parts, which first abrasive may be of a larger size or coarseness, or of a harder material, so as to effect initial abrading and finishing of the parts since at this stage the parts are in a rougher or more unfinished condition. At a second or subsequent blasting nozzle disposed downstream from the first nozzle, the second nozzle can be utilized to discharge a second abrasive media which is different from the first media, which second media may be of less coarseness or smaller size and/or of less hardness so as to effect a more refined or less severe abrading of the parts as they approach the desired finished surface condition. If desired, a third subsequent blasting nozzle can be positioned downstream of the second nozzle and can be used to discharge a third different abrasive media into the flowing mass of parts, with this third abrasive providing a finer finishing of the parts such as effecting a final abrading or cleaning of the parts, so that the parts when discharged from the treating apparatus have been appropriately abraded and cleaned by being subjected to multiple sequential treating steps which progressively refine the treated surfaces so as to achieve the desired end result.  
         [0039]    In addition, after the flowable bulk mass has passed beneath at least a first blasting nozzle, the abrasive media from the blasting spray remains within the flowable bulk mass, and thus this abrasive media continues to tumble with the bulk mass and continues to effect continued abrasive action on the parts being finished.  
         [0040]    While in many use situations the flowable bulk mass will initially be defined solely by a plurality of small parts, such as small molded or formed plastic or powdered metal parts, nevertheless in some situations it may be desirable to define the flowable mass by mixing the parts with a particulate inert carrier, such as plastic particles or the like, so as to provide for desired carrying and spacing of the parts as they are tumbled along the track  15  and specifically as they are tumbled into and through the spray zone. Any such particulate inert carrier will obviously be selected so as to avoid damage to the parts. As an example, the particulate inert carrier may comprise discrete tumbling elements formed from an inert material which is not severely affected by the abrasive media discharged from the blasting nozzles, such as forming the inert tumbling elements from urethane. Such urethane tumbling elements will be shaped and sized so that they do not effectively interlock with either themselves or the parts being treated, and yet the tumbling elements will maintain the parts in the flowing mass in more widely spaced relationship while at the same time providing the desired rolling and tumbling movement of the parts and in fact the different shape of the tumbling elements relative to the parts may increase or provide for a different mode of tumbling movement of the parts, so as to enhance the overall finishing or treating of the parts during their exposure to the abrasive media as the parts move through the blasting zones which are defined in the flowing mass adjacent the discharge from the blasting nozzles.  
         [0041]    While FIG. 5 illustrates the blasting nozzle disposed so that the direction of discharge (discharge axis  51  in FIG. 5) is oriented substantially perpendicular to the upper surface level  40  of the flowing bulk mass  37 , it will be appreciated that desired or optimum performance may be achieved by orienting blasting nozzle  31  so that the blasting direction or axis is oriented at an angle relative to the perpendicular or vertical direction, which angle may be as much as 45° relative to the vertical, and can be angled sidewardly (i.e. transversely) in either direction relative to the vertical, or can be angled forwardly or rearwardly relative to the vertical (i.e., angled forwardly or rearwardly relative to the advancing direction of the mass longitudinally along the channel). In some situations the discharge of the spray  36  may be oriented so that the discharge is angled sidewardly so as to be directed directly into and hence opposed to the circular tumbling direction of the flowing mass. As illustrated in FIG. 5, if the flowing mass is undergoing a circular tumbling movement in the direction depicted by the arrow  52 , then the discharge axis of the nozzle may be angled sidewardly so as to be disposed approximately as indicated by the line  51 ′ in FIG. 5 so that the discharged spray is thus oriented more directly in opposition to the direction of tumbling of the parts as they move upwardly along the side wall of the channel and approach the surface  40  of the flowing mass.  
         [0042]    It will also be appreciated that the tip or discharge end of the nozzle  31  as illustrated in FIG. 5 can also be disposed at varying distances above the surface  40 , and in fact the discharge nozzle can be moved vertically downwardly relative to the flowing mass  37  so that the discharge tip of the nozzle is positioned closely adjacent the upper surface of the mass. Under such situation, a much more intense spraying of adhesive over a smaller discharge zone will occur, although such is also regulatable by means of the pressure of the carrier fluid being supplied to and discharged from the nozzle.  
         [0043]    Referring now to FIG. 7, there is illustrated a variation of the invention wherein, in contrast to FIG. 5, the blasting nozzle in the FIG. 7 embodiment is disposed so that the nozzle discharge tip is associated with a side wall of the treating channel so as to effect discharge of the abrasive-carrying spray directly into the flowing mass. With this arrangement one or more blasting nozzles can again be disposed for disposition at longitudinally spaced intervals along the treating channel so as to permit the tumbling mass to pass progressively through several blasting zones. The mounting of the nozzles so that they are oriented through the channel sidewall hence provides greater flexibility with respect to the structure associated with the upper side of the channel in terms of enclosures and the like and, at the same time, this arrangement of FIG. 7 permits the abrasive-carrying spray as discharged from the nozzle to act more intensively directly on the tumbling flowing mass to effect the desired abrading and treating of the parts. The nozzle when so disposed can again be oriented so that the angularity thereof relative to the channel wall and relative to the flowing mass is selected so as to optimize performance. Further, when using multiple blasting nozzles associated with the side wall of a channel, the nozzles can be positioned so as to be all associated with one side wall of the channel, or different nozzles can be associated with opposite side walls of the channel so as to further optimize the desired treating process. As a still further alternative, some nozzles can be provided on either one or both side walls of the channel, and other nozzles can be positioned above the channel in the manner illustrated by FIG. 5.  
         [0044]    As a still further variation, one or more of the nozzles can, as illustrated in FIG. 8, be disposed so that the nozzle is associated with the bottom of the channel wall so that the abrasive-carrying spray is directed upwardly into the tumbling flowing mass. The blasting nozzle illustrated by FIG. 8 can again be angularly oriented relative to the flowing mass so as to optimize performance, and the generally upwardly oriented discharge of the abrasive-carrying spray is believed particularly desirable for permitting treating of the parts adjacent the bottom of the treating channel in a manner which is generally opposed to the effects of gravity, so that the discharged spray hence tends to effect lifting and hence increases the tumbling and overall random agitation of the parts as they move through the blasting zone created by the upwardly-directed spray. The arrangement of FIG. 8 can, of course, be combined with additional blasting nozzles oriented in manners similar to those illustrated by FIGS. 5 and 7.  
         [0045]    In carrying out the improved treating process of the present invention, it will be recognized that a wide range of particulate abrasive may be utilized for discharge from the blasting nozzles, with the nature of the abrasive being selected according to the finishing treatment desired. For example, if the abrasive constitutes rigid metal grit or equivalent or small metal shot, then the pressure of the carrier fluid as supplied to the nozzle and the discharge velocity from the nozzle will necessarily be higher. If the abrasive from the blasting nozzle is of a softer material such as for effecting fine finishing or cleaning, such as walnut shells, then the pressure of the carrier fluid supplied to the nozzle will be significantly less, and likewise the discharge of the abrasive spray from the nozzle will also typically be of lower velocity.  
         [0046]    Although a particular preferred embodiment of the invention has been disclosed in detail for illustrative purposes, it will be recognized that variations or modifications of the disclosed apparatus, including the rearrangement of parts, lie within the scope of the present invention.