US2770924A - Instant stop and start blasting device - Google Patents

Description

1956 w. H. MEAD ETAL INSTANT STOP AND START BLASTING DEVICE 2 Sheets-Sheet 1 Filed April 1, 1954 T m mnwfl MMBJ E wi /m N A n mwz m HAM T M 4 A 4 um. L MMMU v! a .1 6

INSTANT STOP AND START BLASTING DEVICE William H. Mead, Oakland, Arthur A. Zambruno, San

Mateo, and Alexander L. Jett, Menlo Park, Calif., assignors, by mesne assignments, to William H. Mead, Oakland, Calif.

Application April 1, 1954, Serial No. 420,254 18 Claims. c1. 51-8 This invention relates to a novel method and apparatus for cleaning or treating surfaces and, broadly, has to do with the art of cleaning or treating surfaces in which an abrasive material or substance is impinged against the surface.

The invention provides for the first time a portable, lightweight, efiicient blast cleaning device useful in removing paint, rust, scale or any other deposit from off a surface being cleaned without scattering the removed scale and the spent abrasive over the whole adjacent area. It provides for the first time such a device in which there are no moving parts, thus rendering it fool-proof and easy to maintain. It provides for the first time such a device which can be used in an engine room or other like confined area without requiring adjacent equipment to be covered to protect it from flying abrasive and scale. It provides for the first time such a device in which the flow of abrasive to the blast gun stops immediately upon the closing of the control valve and the abrasive in the supply line is pulled back into the abrasive storage chamber leaving the supply line clear for an immediate start. Other objects and advantages in addition to the above will become apparent as the description of a preferred embodiment of the invention is now given. Also with this description before him the man skilled in this art will be able to devise modifications of the apparatus, because the. invention and its principle is capable of being embodied in more than the one form described in compliance with the Statute. In the drawings:

Fig. 1 is a view in perspective of a somplete apparatus constructed according to the present invention;

Fig. 2 is a diagrammatic representation of the device of Fig. 1, explaining its mode of operation;

Fig. 3 is a view in vertical cross-section through a blast gun of the type preferred for use in the device of Figs. 1 and 2; I

Fig. 4 is a similar view of a separator and reclaimer tank of the type preferred for use in the device of Figs.

1 and 2, taken along the line 44 of Fig. 5, and showing, also, the bypass abrasive control conduit;

Fig. 5 is a top plan view of Fig. 4; and

Fig. 6 is an enlarged detail view of the abrasive outlet from the tank of Fig. 4,'showing the position of the treating material adjacent the outlet when the device is not in operation.

Broadly, the present invention includes a surface-treating head or gun A (see Fig. 2) which is supplied, through a supply line B, with abrasive from the abrasive storage bin C. When blasting, the abrasive is pulled into the nozzle in the gun A and is impelled at the surface being treated by the air jet assembly D. The lower end of the gun A is connected to the suction pick-up line B which has maintained therein a reduced pressure, the net effect of which is to pick up and carry away the spent abrasive and the scale loosened from the work surface. Another efifect of the reduced pressure in the lower end of the gun A is to pull in enough air from the outside through its pervious maze so that none of the abrasive or scale United States Patent can get out from under the gun. Completing this embodiment of the invention is a bypass abrasive control line F, which, in conjunction with the gun control valve G in the air-supply line, and the suction in the abrasive .pickup line B permits a very desirable emptying of the abrasive supply line B, thereby giving instantaneous control over the stopping and starting of the blasting action within the head A. While we have shown a particularly efiicient separator-reclaimer R,.cyclone S and vacuum ejector pump P, these are parts which can be varied and replaced by other devices to perform like functions.

This instanstaneous control over the abrasive flow is achieved by connecting suction lines B and F to a single outlet from the abrasive storage bin C. When there is suction in the line B produced by the jet assembly D in the plasting gun A it is of greater intensity than the suction in the line F created by the ejector pump P so the abrasive flows through the abrasive supply line B to the gun A. The instant the gun control valve G is closed, suction being created by the jet assembly D stops and the abrasive in the supply line B stops moving toward the gun A. Then the suction in the bypass abrasive control line F takes over and draws all the abrasive remaining in the supply line B into the line F and dumps it into the reclaimer R. The. suction in the line F is able to do this because the end 'of line B in the gun A is open to atmospheric pressure. The net result is that so long as the suction is maintained in the line F and the valve G is closed, abrasive will keep cycling through the bypass abrasive controlrline F, through the reclaimer R, then by gravity into the abrasive storage bin C into the T and into the line F. The instant the valve G is opened, the suction created in the line B will draw the abrasive from the bin C through the empty hose B into the gun A. The spent abrasive then returns with the loosened scale to the reclaimer R through the hose E.

Referring to the drawings in detail, 10 indicates the work surface being treated by an abrasive surfacetreating "material 11, in a treating zone 12. This work surface may be wood, glass, metal, cement or a synthetic, and may be covered with paint, rust, scale, or other material 9 which it is desired to remove. The surfacetreating material 11 may be an abrasive or a covering material, depending upon the treatment it is desired to give the surface 10. For purposes of illustration, an abrasive treatment will be dealth with, and this is not intended to mean any relinquishment of the scope 'of interpretation of the invention.

The illustrative apparatus shown in Fig. 1 is movably mounted on a lightweight wheeled frame 13 to permit it to be moved about easily when being used. It is coupled to a source 14 of compressed air by the hose 17. Any type of air-velocity means or pressure accumulator 14, such as a motor-driven conventional air compressor, may be used. Preferably, a constant pressure outlet valve 15 is interposed in the line to regulate the pressure and volume of air metered to the surface-treating apparatus from the source 14.

Compressed air is piped from the source 14 through the inlet conduit 17 to a main hand-operated valve V on the unit. Upon opening the valve V, the air passes into an aridifier or moisture trap 18 which separates the moisture in the air stream and permits the moisture to be blown down through the valve 19. From the aridifier the air passes through the conduit 20 and is divided into branch conduits 21 and 22. The conduit 21 conducts the air to an ejector pump P which creates all the suction needed for the spent abrasive and scale pick-up line B and for the bypass abrasive control line F. The conduit 22 conducts air to the jet assembly D where the air :flow performs the dual function (a)"of sucking the abrasive material 11 from the T where it has fallen by gravity from the storage bin C, and through the abrasive supply line B into the jet assembly D on the gun A; and (b) of impelling the abrasive at the work surface 10.

The main suction system The suction circuit initiated by the air flowing into branch conduit 21 will be considered first. As indicated in Fig. 2, the compressed air passes from the conduit 21 into the ejector pump P where it is jetted through an annulus 23 at very high velocity into the throat of a mixing tube. By adding the ditfuser 24 the maximum energy is taken from the air flow. By properly proportioning the annular throat of the ejector pump, the size of the diffuser and the volume and velocity of the entering air, the ejector pump can be made to entrain the air from the conduit 25 and produce the desired degree of vacuum. The vacuum or subatmospheric pressure, thus created supplies the suction in the spent abrasive and scale pick-up line E leading from the blasting gun head A, and acts to pick up all the loosened scale and the spent abrasive as soon as it has impinged against the work surface in the treating zone 12. The pump P and associated conduits thus act as a source of suction connected to the reclaimer R.

The suction created by the ejector pump P, in addition to the foregoing, also supplies the air flow needed in the separator and reclaimer R, in the cyclone S, and in the bypass abrasive control line F making the same air do double duty, that of conveying and air washing the reusable abrasive.

The separator and reclaimer R It is a feature of the preferred embodiment illustrated that all the spent abrasive 11 removed from the zone 12 be reused many times which requires that it be separated from the entrained dirt and debris after each trip to the gun A. To achieve this result, a suitable separator-andreclaimer tank R is needed. It should be noted, though, that the invention may be employed without a reclaimer positioned between the suction line E and the ejector pump P. The form of separator and reclaimer shown in Fig. 4 has an upper chamber with a novel system of bafiles and passageways which are particularly effective in separating the abrasive from the entrained dust and scale. The latter then pass on to the cyclone S where the scale and most of the dust is captured in the receptable 29 below the cyclone S. If there is an especially large amount of dust being lifted off the work surface, that part which is not caught in the cyclone will be caught in the dust bag 51. For most work the dust bag is not needed.

In operation, the tank R acts to separate and reclaim the abrasive 11 from the fines and debris 26 removed from the treating zone 12 by the suction pick-up line E, so thatthe abrasive may be collected for reuse inthe lower reservoir portion 30 of the tank. As the mixture of scale and abrasive enters the tank R, it is directed by the tangential inlet '32 in a circular path within the battle 31. Centrifugal force genenrated by this circular motion accomplishes an initial separation of the abrasive and scale particles from the air stream so that the abrasive and scale will be spread out over the relatively large area of a conical slide 33. An intermediate oppositely directed baffie 34 restricts the downward flow of the air stream and also acts to deflect the abrasive and scale particles which are moving on or close to the wall 31 onto the upper surface of the stratifying slide 33. As the abrasive and scale particles move down the conical slide 33, the increasing surface area presented permits the particles to spread out and for each particle to come into contact with the slide rather than to remain piled on top of another particle. Consequently, when the solid particles cascade over the lower perimeter of the cone 33, as a film about one layer thick, the relatively heavy individual particles of abrasive and the relatively light more circuits around the chamber 31, meanwhile flows up the channel 35 formed by the annular flange 36 surrounding the discharge pipe 37 by reason of the larger area. It then moves down the annular channel 38 formed between the outer tank wall 39 and baifle 31. The air takes this path because of the restriction formed by the relatively narrow gap 39a between the cone 33 and the deflecting baflie 34 which only lets a small amount of the air through this gap. Thus the bulk of the air sweeps down the channel 38 and through an annular opening 40 between the cone 33 and the lower adjustable cone 41. As a result, the cascading abrasive and fine particles are subjected to a cross-current of air which sweeps the fines, scale and dust particles into the space between the cones 33 and 41 into the discharge stack 37 and over into the cyclone S. The heavier abrasive particles fall by gravity into the abrasive storage bin C through the gap at the lower periphery of the cone 41. Any oversize particles that escaped removal above are caught on the sloping screen 42. The screen '42 also serves to remove any oversize particles in the abrasive when it is first loaded into the bin C through an opening 104 provided for that purpose. A door 103 enables any screened coarse material to be removed periodically. A curved baffle or floor 43 is provided to guide the abrasive toward the outlet 44 leading to the abrasive supply and control lines B and F.

The effectiveness of the separator and reclaimer R is dependent on having the proper velocity of the crosscurrent air sweeping into the gap between the cones 33 and 41. The necessary range of velocities will vary with the types of abrasive material used. This velocity must be great enough to carry the individual dust or scale particles out from among the abrasive particles so they will be swept up between the cone 41 and cone 33 and then out the pipe 37. The cone 41 has less slope than the cone 33 (see Fig. 4) thereby providing a space be tween them which increases in area in the upward direction. Thus, should a reusable abrasive particle be unswept into the area, the progressive enlargement of the area will slow the air flow and will allow the particle to settle and return to the opening 40 and to fall down into the storage bin 30. In general, the air velocity of this cross-current must not be great enough to pick up the abrasive particles themselves, as they should fall in the first instance into the abrasive storage hopper 30. To adjust the air velocity the lower cone 41 is raised or lowered to vary the width of the entry gap 40 between the two cones 33, 41. Thus, if a relatively heavy abrasive is used, such as steel grit having a mass of aproximately 265 lbs/cu. ft., the cone 41 would be raised to decrease the gap and thereby achieve a relatively high sweep velocity. With a lighter abrasive, such as sand (approximately lbs./cu. ft.), the cone 41 would.

be lowered, thereby widening the gap and lowering the velocity of the air so it would not sweep the sand particles up the conduit 37 along with the scale. A suitable adjusting means for this purpose is illustrated in Fig. 4, which shows the cone 41 adjustably mounted on a vertical shaft 45 by a sleeve 46 and adjusting screw 47. Of course, any other convenient means could be used. For certain abrasives, such as ground walnut shells (35 lbs/cu. ft.), it may be desirable to remove the cone completely to further reduce the sweep velocity.

Separating the air from the dust and scale After leaving the separator and recl'aimer R,the debris and dust-laden air is sucked through conduit 48 into a conventional cyclone separator SLwhereathe bulleofl any;

contaminant-s remainingin the :air are removed'by centrif? ugal for'ce'. The solid particles are thrown againstthewall.

50' and conduit 25" into the ejector pump P which constitutes the source of the suction circuit. The suction circuit-is completed when the air is exhausted from the pump P through the diifuser 24. Preferably, a-dust bag 51surrounds the diffuser so that any remaining fine dust willibe.

removed from the airbefore it is exhausted to the atmosphere.-

The blast gun suction system Next tobe considered is-the. air blast circuit supplied by the branchconduit 2'2 which leads-into thebl'asting gun A. As shown in Fig. 2, the-air passes fromthe line' 22; throughrnanual c'ontrolvalveG, into the jet'assembly D, where it serves the dual-functional) of sucking the |abrasive-11 through the abrasive supply line B from the abrasive reservoir 30 and (b) of impellingjthe abrasive at the? work surface enclosed within the blastinggun A1 Broadly thisfunction is achieved by surroundingthe jet- 60 leading'from the abrasive supply lineB with a mixing. Air passing through the annular orifice 6'2"- tube 61. formed between'the two members 60 and 61 will pull'air from the abrasive supply line B. The motion-of the air wil-l'carry the abrasive 11 through theb'ore of the-jet nozzel 60 depositing itin frontof the blast of air emerging up the-abrasive and:

from the orifice 62 which blast picks impels-it against'the work surface Within theblasting gun orhead'A, it is important that two impinging aircurrents are provided so that the blast ing and pick-up elfect, described in the Mead U. S. Re-' issueP-atent No. 23,186 will be present. One of these currents is the air blast from line 22 which'sucks the abrasive through the jet and throws it against the work surface :10. The other current is the flow induced in the suction pick-up line B which causes an 'air'sweep into-the head A through an air-.pervious mazeor impeding-means 63-conneotedto the casing SI-andicontacting the work surface 10. These two currents meet just inside the maze orxair-pervious deflector means and form :a pick-up force I Whichlifts the spent abrasive and the scale upwardly and out through the pick-up line E. In this respect the operation of the blast gun A is identical 'witht-hatdescribed in the above patent, wherein the net effect is a completescavenging of the @work area within the treating zone of all scale and spent-abrasive without any 'ofthe abrasive or scale gettingthrough' the maze-63where it might in' jure delicate machines-and other finished surfaces.

The I blasting gun A An'illus-trative apparatus fortheblastinggun and-head A is presented in-Fig. 3, which shows an inner casing or shell 72 which serves to direct'onto'the 'surfiace 10 the abrasive 1 1 issuing from the jetassembly D. The mouth 74 of thecasing 72 confines the work area 10 to the treat iug zone 12. A-second or out-creasing 75'surrounds the inner casing 72 adjacent the mouth 74 of the latter. How far up the outside of the casing 72-the-outer casing extends is. a matter of choice, the critcrionbeing a size and shape that will givea sustained'velocity to the'air flowindicated' by the arrows 76* so that the air currentwill have a high weight-sustaining or carrying characteristic. This charac-- The-maze '63; batfie and body 81" may be thought 'of as constituting,- togetherwith other associated parts, a hood that encloses a portion of the surface aroundthe area being...

treated Adjustments for difierent quantities of abrasives One feature of the apparatus illustrated inFi g. 3 is-the provision for an adjusting means within the jet assembly.

D so that any desired amount of abrasive may be caused to flow in :a given time intervalto'fit the requirements of dilferent abrading operations. Thisadjustment may'be achieved by a threaded connection 83 between the-separate structures-of the jet nozzle 60:=and=the-mixing tube 61. By manipulating the threaded connection 83,- the annulargap 62 between the :jetand the mixing-tube may be widenedor narrowed. The extentof the" adjustment may be gauged by the numberof shims-82 interspersed metering orifice 851's provided "in the-feed outle-t44, so 3 that .the flow of abrasive into the abrasive supply-line B wil-l be regulated'to cause the amount of abrasive 1 02;

droppinginto the pipe tee 90 beneath the pipe 44'- to equal what the flow of air created by the jet D cancarry Thus, the relationship between th'eannular orifice 62and the metering insert 8 5 is such that the orifice 85 will be increased in size, as the gap-in the orifice 62 is-increased. The right size of orifice 85 will allow only theamount of abrasive to fall into the-tee 90, as can be airborne by the flow of air created-by. the jet D. The only-time the abrasive 102 lies in the pipe 'is when the-valve V closed.

Abrasive control mechanism Early in this specification appeared an explanation of the broad structure by which instantaneous control over the abrasive is obtained in a very simple and unique manner. This structure is shown in detail in Figs. 2 and'4, where the by-pass abrasive control line-F is connected to" one end of'a T fitting .90 secured to the abrasive storage bin outlet 44, and at its other end it is connectedinto the suction pick-up l-ine E at some. convenient point, preferably just before the line B enters the reclairnertank R. The other end of the T-fitting 90 is connected to the abrasive supply line B leading into the blasting gun and: head A. In operation, the function of the bypass control line F is closely tied'in with the operation of the'cont-rol valve G which supplies air to the jet assembly D. When the valve G is open, the air passing through the orifice gap 62'creates a flow of air in the supply line B'which picks up the abrasive in the T-fitting 90 below theorifice 85 and carries the abrasive from the abrasive storage bin C through the jet 60 into the blastinghead-A'.

In normal operation, the suction at the abrasive supplyline B side of the T-fitting 90 is proportioned to be somewhat greater than that in the bypass line F so that when the valve G is open the flow of air and abrasive-is to the blasting gun A. During. this stage of the operation,- termed for convenience the blasting stage, the jet assembly D assumes complete control over the through the blasting head A and back to the separatorrec'laimer R through the pickup, line E. The path of thisblasting cycle is indicated by the arrows in Fig; 2. It is apparent that any abrasive particles movingin-thiscycle in the supply line B will develop considerable kinetic energy as they are sucked into the blasting jet- 60.

The importance of the bypass control line Flies in its. instant ability to overcome the kinetic energy of the flow:

line B back away from the nozzle 60'." Another important.

abrasive cycle valve G. Thus no complicated electrical or other remote controls and no extra valves are needed.

Operation The over-all operational cycle of the abrading apparatus disclosed is as follows:

A suitably-sized orifice 85 is inserted in the feed outlet 44 and the orifice gap 62 in jet assembly D is adjusted for the particular quantity of abrasive 11 that is to be fed in the abrading operation. Also the cone 41 is set to provide the proper gap 40 in the reclaimer R. A charge of the desired abrasive is then placed in the reservoir 30 through the filling spout 104 above the screen 42. At this stage the abrasive seeks its level through the screen 42, outlet 44, and orifice 85 and forms into a mound in the T-fitting 90, with its angle of repose generally as shown in Fig. 6. The device is then ready to be rolled up to the work area on its wheeled frame B, where a connection 16 may be provided to a compressed air source 14. The blasting gun and head A is then placed on the work surface 10 preparatory to blasting.

Blasting is initiated by first opening the main valve V which starts the ejector pump P in the suction circuit. At this stage air begins to flow into the reclaimer R, and the cyclone S (a) through the pickup line B, and (b) through the abrasive supply line B, the mixing tube 61, the cone 72, the maze 63, and the bypass line F. Through the pickup line B the suction circuit applies an operating vacuum on the treating head A, while the suction in the bypass line F scavenges the build-up of abrasive material in the T-fitting 9t) and also acts to clean out the feed outlet 44 and orifice 85 prior to actual blasting operations. The abrasive continues to cycle from the outlet 44 through the line F into the reclaimer R. To start actual blasting the control valve G is opened to admit the air blast to the chamber in the jet assembly D, so that it may pass through the orifice gap 62, causing the blasting jet 60 to produce a suction in the line B. Suction in the line B causes the abrasive falling through the orifice 85 into the T-fitting 90 to flow into the abrasive supply line B, into the blasting jet 60, and onto the work surface. There the abrasive elfects a loosening of whatever scale or coating 9 may be covering the surface 10. After the abrasive material 11 impinges on the work in the confined area, this material 11 immediately comes under the influence of the air stream flowing inwardly through the maze 63 in the blast gun A, with the result that the two air streams impinge and lift off the surface 10 the spent abrasive and the loosened scale or coating. These are conveyed away out of the operating head A through the flexible pickup line B and into the separator R. The blasting gun A is moved over the working surface 10 as fast as the scale is removed. In the drawings it has already moved over the surface lying to the right of the treating zone 12 and is being moved to the 'left to clear that surface of the scale 9.

In the reclaimer and separator R the scale and dust is separated 'from the abrasive and the latter drops into the abrasive storage bin 30. The dust and scale go on to the cyclone S where most of the scale and dust is removed from the air. As a final step in very dusty work the air is passed through a dust bag 51 before being exhausted. The blasting operation can go on continuously as the abrasive is used over and over again.

When the operator wishes to lift the blasting gun A off the surface 10 for any reason he closes the valve G which stops the flow of air to the jet orifice 62. This discontinues the suction in the abrasive supply line B in the direction of the arrow 100 and the suction in the bypass abrasive control 'line F takes effect reversing the flow of air in the abrasive supply line B and in the bypass line F so the abrasive in the line B is pulled back away from the nozzle 60 and is carried through the line F into the reclaimer R. As soon as the line B is cleared, more abrasive is picked up below the orifice and there is a continuous cycling of abrasive in the direction of the arrows 101 (Fig. 4) until either (a) the ejector pump P is shut down or (b) the valve G is opened and blasting is resumed.

By combining the maze 63 and the blasting gun A with the conduits B, E and F, the maze not only performs the functions set forth in Reissue Patent No. 23,186, but it performs in this new combination the additional function of providing an inlet so that air may flow freely in the reverse direction to those denoted by the arrows in conduit B whenever the gun valve G is closed.

As noted earlier, the device illustrated is a preferred form and this description is not intended as a disclaimer of other forms in which this invention may be embodied. Also attention is called to the fact that in lieu of the ejector pump P any other suitable source of vacuum may be substituted. Also, where abrasive is plentiful and need not be reused the pickup line B would go directly to the vacuum source, omitting the reclaimer R and the cyclone S. The bin C would be kept filled with abrasive and the instant the blast gun A was turned off the bypass line F would clear the abrasive supply line B. If the gun A were to remain inactive for any length of time, a suitable valve at the bottom of the bin C could be provided to avoid wasting the abrasive.

From the foregoing it will be apparent that this method and apparatus make possible the use of a small, portable treating device that is ideally suited for use around delicate machinery, as in automobile repair shops, or on shipboard, or in closed rooms, or in any area or application where complete and instantaneous control over both the treating action and the treating material is required. Thus, with the present invention not only is the area of treatment controlled, since there is no escape of the treating material from the treating head, but also the time of treatment maybe carefully controlled, since the flow of abrasive to the work area can be instantaneously started and stopped without any time lag.

To those skilled in the art to which this invention relates, many changes in construction and widely difiering embodiments and applications of the invention will suggest themselves without departing from the spirit and scope of the invention. The disclosures and the description herein are purely illustrative and are not intended to be in any sense limiting.

We claim:

1. A surface treating device comprising a supply source for the treating material; a reclaimer separator having an inlet, an air outlet, and a connection to said supply source and adapted to deposit cleaned treating material in the latter; a blasting gun for directing said material at said surface; control means for activating and inactivating said gun; a hood enclosing said gun, said hood having an open end with a pervious maze bordering said end to enclose a portion of said surface around the area being treated; a source of suction connected to said air outlet from said reclaimer; a first conduit connecting said hood to the inlet on said reclaimer; a second conduit connecting said supply to source to said gun; means for producing simultaneously a suction in said second conduit and an impelling force in said blasting gun whereby treating material will be caused to flow in said second conduit to said gun; a third conduit connecting said second conduit and said supply source to the inlet end of said reclaimer and therethrough to said source of suction; whereby upon activation of said gun, the suction in said second conduit will move said treating material to said gun as needed, and the suction in said first conduit will remove from the surface area enclosed by the hood the spent treating material and through said second conduit thereby moving outof' said second" conduit into said" third conduit and into. said reclaimer'" any treating material in, said second conduit; and so'long as the source of'suction is connected'to said treclaimer and said gun is, inactivated; said treating material'will be cycled through said third-conduit, said reclaimer'and said supply source.

2. A surface treating device comprising a supply source for the treatingmaterial; a blasting gunfor directing said material at said-surface; control means for activatingfand inactivating said gun;,a hood enclosing said gun, said hood having an open end'with a pervious-maze bordering ,said endvto enclose arportion of said surface around the area beingtreated; a source of suction; a first conduitconnecting saidsource of suction to said hood; a second conduit connecting said supply source to said gun; impelling means for producing simultaneously av suctionin said second-conduit and an impellingvforcein said blasting gun whereby treatingsm aterial will be caused to flow in said conduittosaid gun; a thirdiconduitwconnecting, said second. conduitand said supply source to saidsource of suction;.whereby upon activation of said.

impellin-gmeans, the.suction in said second conduitwill move said treating material to said:impelling means as needed,.and uponhinactivationofsaidgun, the suction in said thirdiconduitwill become effective inv said. second conduit to move. any treating material'therein'into' said third conduit and away. from saidgun.

3. A surface treating device comprising a-supplysource for the treating material; anblasting gun for directing; said. material. at-said surface; a hood enclosing said gun and .having, an open end to enclose I a portion of said' surface; a source ofsuction; a conduit connecting said source. of. suetionto said hood; a-secondconduit con necting. said.supply source to said blasting gun; means. for producing simultaneously a suction. inisaid second conduit and an impelling force in said blasting gun whereby treating material will be caused to flow in said conduit suction-removed'abrasive having air: compressor"m'eans for impelling said abrasive at-thesurface being treated,

vacuum means forconveying the: spentiabrasive away from-said surface; and bypass control'means for elim inating time lag in the operation of the device; thecombination of a-treating head'spaced slightly above and having an air-pervious maze" adapted to cover-over aportion of the surface being treated, said treatinglhead' having anopen. end, .a; jet 3 means therein withits"- open end pointed towardthe opentend ofsaid headandwith' its other end connected'tossaid air compressor andto'a supply line in communication with a source of abrasive, a vacuumconduit from'said head to said vacuum means,

albypass control line leading from-said vacuum' conduit" to both said supply line and said-sourceof abrasive; and

a control valve interrupting'the flowof abrasive from said air compressor'to said jetmeans, wherebyorr closing said valve during normal operation of the-device; a

flow ofabrasive'throughsaid supply line into said treating head will'be instantaneously"redirected throughsaid bypass'vcontrol line.

5. Ina device-for treating a surface with an'air-blasted;

suction-removedabrasive. having high air velocity means for impellingisaid. abrasive. at .the surface being treated," and for producing. reduced. pressure: for conveying the spent abrasive away fromsaid surface, and havinga'by pass controlmea'ns "for-eliminating time lag in the operation ofthe device; the-combination of a treating h'e'ad spaced slightly above and having anair-pervi'ous maze adapted to cover over a" portion of the surface being.

treated, said treating head having an open end, a jet means'thereinwith'its open end pointed toward'the openend" of said head for impelling said abrasive at said surface, and adapted to be energized by'said air'velocity,

means; a first conduit forming a supply line between a source of abrasive and" said jet means, said jet means creating a reduced pressure in said supply line to induce a flow of abrasive therein to said jet means, a secondconduit connecting saidhead to said air velocity means for conveying the spent abrasive away from said surrupting. the flow of air from said air velocity means tosaidjet means, whereby on closing saidvalve to end the blasting operation said jet means is de-energized causing the pressure at the outlet end of said second conduit to become lowerthanthe pressure at-the outlet end of said first: conduit so that the flow of abrasive through said first conduit is reversed and flows through said third conduit.

6. An apparatus for treating a surface with an airblasted, suction-removed abrasive and for substantially eliminating time lag in 'theoperation of the apparatus,- which com-prises a treating head, including deflecting and impeding meansltoprevent loose material from flying about and'to confine the areaof treatment, a source of abrasive, a supply line from said abrasive source to the head, a suction circuit, an exhaust connection between said suction circuit and said head, separating and reclaiming means for said abrasive interposed in saidsuction' cir-' cuit, a bypass suction lineleading from said suction cirwit to aconnection with both-said supply line and-said abrasive source,- air*jet means in said treating head connectedto said abrasive'supply line, and valve means regulating-the flow of-air to said-jet means, whereby during a blastingstage of operation said jet means creates sufficient pressure to such abrasiveinto a jet blastingv action insaid head from which bothspent abrasive and loosened debris' may be removedfrom the surface by the suction circuit and the abrasive returned to saidabrasivesource through said separating and reclaiming means, but on closing said valve said bypass line' redirects the flow of abrasive away from. the treating head into an abrasive recycling. stage of operation through said separatingandreclaimingmeans, thereby permitting instantaneous stopping of the abrading action upon valve closure.

7. The device of claim 6 in which said source of abrasive comprises'a hopper inthe' bottom of said separating and reclaiming means, a feed outlet from'said hopper, and

a T-fittinglconnecting said outlet"v to said bypass control line and .said' abrasive supply line.

8. The device of claim 7 wherein said feed outlet is 1 providedlwith an orifice to meter a predetermined amount of abrasiveinto the air stream leadingto sa-id jet means and treating head.

9.. An apparatus for treating a surface with an' airconnecting said apparatus to a sourceof compressed air,

anejector pump connected to a branch conduit of said air supply line to create a suction circuit, a-jet assembly connected to another branchconduit of said airsupply line to create an air-blasting circuit, a treating head coupled with said jet assembly to utilize said air blast, said head including an air-pervious surface-contacting means to confine the movement of loose material to an area within the head, a source of abrasive, a supply line from said abrasive source to said jet means, said jet means creating a vacuum in said supply line to induce the flow of abrasive into the air blast in said head, an exhaust connection between said suction circuit and said head, separating and reclaiming means for said abrasive interposed in said suction circuit, a bypass suction line leading from said suction circuit to a connection with both said supply line and said abrasive source, and valve means regulating the flow of blasting air to said jet assembly, whereby during a blasting stage of operation abrasive material is sucked through the supply line, blasted at the surface, removed through said suction circuit and reclaimed in said separating and reclaiming means, whereas on closing said valve means said bypass line redirects the flow of abrasive away from the treating head into an abrasive recycling stage of operation through said operating and reclaiming means, thereby permitting instantaneous stopping of the abrading action upon valve closure.

10. An apparatus for treating a surface with an airblasted, suction-removed abrasive and for substantially eliminating time lag in the operation of the apparatus, which comprises'an air supply line for connecting said apparatus to a source of compressed air; an ejector pump connected to a branch conduit of said air supply line to create a suction circuit; a jet assembly connected to another branch conduit of said air supply line to create an air-blasting circuit; valve means regulating the flow of blasting air to said jet assembly; a treat-ing head coupled with said jet assembly to utilize said air blast, said head including an air-pervious surface-contacting means to confine the movement of loose material to an area within the head; a source of abrasive; a supply line from said abrasive source to said jet means, said jet means creatinga reduced pressure in the outlet end of said supply line to induce the flow of abrasive into the air blast in said head; an exhaust line connecting said suction circuit to said head; separating and reclaiming means for said abrasive interposed in said suction circuit; a bypass line leading from said suction circuit to a connection with both said supply line and said abrasive source, the pressure at the outlet end of said bypass line being higher than the pressure at the outlet end of said supply line during blasting and being reversed when said jet means is inactivated by closing said valve means; whereby during blasting abrasive material is moved through said supply line, is impelled at the surface being treated, is removed through said suction circuit and reclaimed in said separating and reclaiming means, and upon closing of said valve means and flow of abrasive in said supply line is reversed thereby effecting an instantaneous stopping of the abrading action, and thereafter the abrasive cycles from the abrasive source through said bypass line into said operating and reclaiming means and back to said abrasive source until said valve means is again opened to resume blasting.

11. In a devicefor treating a surface with an airblasted, vacuum-removed abrasive having air compressor means for impell ing said abrasive at the surface being treated, vacuum means for conveying the spent abrasive away from said surface, and suction control \means for eliminating time lag in the operation of the device; the combination of a treating head spaced slightly above and having an air-pervious maze adapted to cover over a portion of the surface being treated, said treating head having an open end, a jet means therein with its open end pointed toward the open end of said head and with its other end connected to said air compressor and to a supply line in communication with a source of abrasive, a vacuum conduit from said head to said vacuum means, a suction control line leading from a source of reduced pressure directly to both said supply line and said source of abrasive, and a control valve interrupting the flow of air from said air compressor to said jet means, whereby on closing said valve during normal operation of the device, a flow of abrasive through said supply line into said treating head will be instantaneously redirected through said suction control line.

12. An apparatus for achieving instant control over the abrading action involved in treatment of a surface by impinging loose solid abrasive material against the surface which comprises a source of abrasive material, an air jet creating a source of reduced pressure in an abrasive supply line leading from said material source, thereby inducing flow of the material to the surface, an independent source of reduced pressure operable in a pickup line adjacent the surface to induce fiow away from the surface of both said material and of solid particles removed from the surface, and a bypass line con meeting said independent source of reduced pressure to said material source and said abrasive supply line, whereby on closing of the air jet, said independent source of reduced pressure will operate through said bypass line to instantaneously redirect the flow of abrasive material away from said jet.

13. A surface-treating device, including in combination: a supply source for treating material; a blasting gun for directing said material at said surface; a first conduit connecting said supply source to said gun; gunactuating means for producing simultaneously a first suction force in said first conduit for causing said material to flow from said source to said gun, and an impelling force in said gun for projecting said material at said surface; control means for alternately rendering said gun actuating means operative and inoperative; a second conduit connected to said first conduit between said supply source and said gun; and means for producing a second suction force on said second conduit of lower magnitude than said first suction force and therefore not able to interfere with the movement of material from said supply source to said gun while said gunactuating means is operative, but, when said gun-actuating means is inoperative, serving immediately to redirect said material away from said gun and through said second conduit so that then said material never reaches said gun.

14. In an apparatus for treating a surface with a loose abrasive material, for providing instantaneous stop-andstart control over the treating action, and for collecting and preventing loose material from such treatment from flying about, said apparatus having a casing with an open end; suction means connected to said casing; jet means within said casing for projecting said material at said surface through said open end; air-permeable, mazelike impeding means projecting from said end and impeding the exit of said material while said suction means draws in air through said maze-like means and carries away said material; a source of said treating material; and a supply conduit connecting said source to said jet means; the combination therewith of: a bypass control conduit connecting said supply conduit to said suction means; means at said jet means for producing a suction force on said supply conduit greater than that produced thereon by said bypass control conduit; and means for rendering said jet means alternately effective and ineffective, whereby when said jet means is effective it immediately draws material from said supply source and projects it through said gun and when said jet means is ineffective said suction immediately acts through said bypass control conduit to reverse the flow of said material and move it away from said gun through said bypass control conduit.

15. In an apparatus for treating a surface and having a casing with an open end spaced slightly above said surface, air pervious deflector means secured around said open end and adapted to rest on said surface and surround the space between said open end and said surface, and suction means connected to said casing, the combina- ;tion therewith, for the purpose of substantially eliminating time lag in the operation thereof, of: a source of treating material; a supply line connecting said source of treating material to said casing; a control line connecting said supply line to said source of suction and bypassing said casing; jet means projecting within said casing and forming the connection of said supply line to said casing; means for supplying air under pressure to said jet means; and valve means regulating the supply of said air to said jet means, said valve in open position creating a force of suction on said supply line greater than that in said control line so that treating material passes through said supply line to said jet means and is projected thereby against said surface, whence it is withdrawn by said suction means without passing outward through said deflector means, whereas said valve in closed position re sults in said treated material reversing its flow to said jet means and flowing away therefrom through said control line.

16. A device for achieving instantaneous control over the stopping and starting of abrading action involved in surface-treating operations of the type where loose, solid abrasive is impinged against a surface, said device including in combination: a treating head; a source of abrasive; an air jet connected to said head and creating a reduced pressure within a portion of said jet; a supply line from said source to said jet, said reduced pressure inducing flow of abrasive therethrough; a second source of reduced pressure connected to said supply line and exerting a lesser force than that of said jet upon said supply line and said source of abrasive; an air source supplying said air jet; and a valve for interrupting the flow of air from said air source to said jet, whereupon said source of reduced pressure immediately reduces the flow of abrasive away from said head.

17. The device of claim 16 in which said air jet includes a nozzle in communication with said source of abrasive and a mixing tube spaced about said nozzle to produce an orifice gap between the two, said nozzle being axially adjustable with respect to said nozzle to vary the dimensions of said orifice gap, whereby abrasive materials of varying quantities may be impelled at the surface.

18. A device for achieving instantaneous control over the stopping of a surface abrading action produced through the impingement of granular abrasive against a work surface, including in combination: a source of abrasive; first suction means for moving said abrasive material from said source and toward and against said work surface; a second smaller suction means opposing said first means; and means for instantaneously stopping said first means so that said second means reverses the flow of abrasive material and instantaneously stops the abrading action against the work surface by redirecting said abrasive.

References Cited in the file of this patent UNITED STATES PATENTS 2,365,250 Crowley Dec. 19, 1944 2,455,514 Mead Dec. 7, 1948 2,483,176 Bishop Sept. 27, 1949 2,494,773 Mead Jan. 17, 1950 2,503,743 Keefer Apr. 11, 1950 2,521,931 Mead Sept. 12, 1950 2,597,434 Bishop May 20, 1952 FOREIGN PATENTS 614,087 France Sept. 11, 1926

Images