US2200587A - Method and apparatus for sand blasting - Google Patents

Description

May 14, 1940. TURRELL 200,587

METHOD AND APPARATUS FOR SAND BLASTING i Filed Feb. 25, 1937 2 Sheets-Sheet 1 NN mv KN. NN k N N QN NN Q @I .JQN @NNW NNRN Q. NN ,WN 01%, NN .NQWMQNJ May 14, 1940- l.. l.. TIRRELL 2,200,587

METHOD AND APPARATUS FOR SAND BLASTING "TPatentecl May 14, 1940 METHOD AND APPARATUS Fon SANDv BLAs'rmG Leslie L. Tirrell, Benton Harbor, Mich., assixnor to The Hydroblast Corporation, Chicago, Ill., a corporation of Illinois Application 'February z5, 1937, serial No. .127,620

27 Claims.

This invention relates to a method and apparatus for sand blasting devices, and more particularly to a m'ethod and apparatus for cleaning by abrasion which includes means whereby surnozzle retaining sleeve with means for cleaning the thread of the gun body when the two are screwed together.

A further object is to provide a method and tionship to each other so that a chamber I2 is DEC 14 i948 5 faces are abraded with a Wet abrasive by the inapparatus for cleaning by abrasion in which the 5 troduction of a supply of air and abrasive into abrasive, after a cleaning operation, may be cola Water stream, operated under high pressure. lected, classified, and recirculated through the The present application is a continuation in machine. part of my earlier application, Serial No. 37,585, y Another object of my invention is to provide filed August 23, 1935. V a process and apparatus for cutting coherent 10 The main object of my invention is to provide solids which reclaims and' utilizes particles cut a method and apparatus for sand blasting which from the solid as abrading material. utilizes a liquid carrying medium for projecting A further object is to provide a. feeder in conabrasive material at high velocity and entrains nection with the collecting means for the used i5 a large amount of the abrasive material in a Vsand or particles, and in which a suction is crel5 concentrated and forceful stream. ated by the gun for lifting the sand from the Another object of my invention is to provide collecting means. apparatus and a method for controlling the 'A further object is to provide means within spread of a, projected stream of liquid carrying the feeder for keeping the sand and water in a medium, such as water, having sand or other mobile condition and to provide easy starting 20 abrasive material entrained' therein whereby the of the gun after a period of inoperation.' stream may be varied from a thin concentrated With the above and other objects in view the pencil to awide spray. invention resides inthe method together with Afurther object is to provide a method and the` combination and arrangement of parts 'as apparatus for abrading in which particles and hereinafter set forth, shown in the drawings, 25 air are fed to separate chambers of a gun described and claimed, it being understood that through depressions in air pressure created in changes in the precise embodiment of the inn said chamber by fluid jets passing through each vention may be made within the scope of what chamber from a nozzle of vone cross sectional is claimed without departing from the spirit of 3g area to a nozzle of greater cross sectional area. the invention. so

A further object is to effect controllable con- In the drawings: A finement of a projected liquid stream by securing Fig. 1 is a vertical longitudinal sectional view the entrainment of highly rareed air thoroughof. the gun; ly and substantially equally distributed within Fig. 2 is a vertical longitudinal sectional view the stream, for the accomplishment of which I ofthe swivel joint between the inlet water hose 35 use two nozzles in tandem behind the final disand the gun; charge nozzle and admit air in controlled Fig. 3 is avertical longitudinal sectional view amounts to the stream as it passes between said of the feeder; f

I tandem nozzles. y Fig. 4 is a sectional View of the feeder cut 40 A further object is to provide a simple method along the line of 4--4 of Fig. 3; 40 and means for vcleaning the abrading material Fig. 5is avertical longitudinal sectional view from the gun, piping, and feeder. through the platform, and sand classifier, showx A further object is to provide the cut-off valve ing the feeder in the tank, and the gun and for the water stream with a self-sealing packing water supply connected therewith; and gland which needs no tightening or other ad- Fig. 6 is a sectional view of the gun cut along 45 justment. the line 6-'6 of Fig. 1.

, A further object is to provide a self-sealing Referring tor-the drawings, and particularly to swivel joint for the high pressure'water line, a Fig. 1, which shows the gun as a whole, the gun feature of this joint being that-it compensates comprises an elongated casing i tted with a for wear on the packing material Without hand hand grip 2 at the forward end and an arm rest 50 adjustment and constantly assumes the mini- 3 at the rear. Inside this casing is a tube l mum degree of resistance to turning consistent made up of the axially aligned sections 5, 6, 1, with the pressure against which it is required 8, and 29. Inside the tube @are arranged three to maintain a seal. tandem nozzles, 9, i0, and Il, in spaced rela- A further object is to provide the discharge 55 provided inside the tube 4 between the rear noz? zle II and the intermediate nozzle IIJ and another chamber I3 is provided between the intermediate nozzle I0 and the front nozzle 9.

The opening in the intermediate nozzle I0 is larger than that in the rear nozzle II, but smaller than the opening in the front nozzle 9. Therefore, it will be seen that as the high pressure fluid stream leaves the rear nozzle I I and passes through the chamber I2 and intermediate nozzle I0, no back pressure will result since the natural expansion of the stream is compensated for by the increased cross-sectional area of the middle nozzle I0. In a like manner the increased diameter of the stream as it passes from the middle nozzle I0 to the front nozzle 9 is provided for by the larger opening in the front nozzle 9. A nozzle casing 5 forms the holder for the resilient discharge nozzle 9 and consists of a sleeve with a forward cut-away section of reduced diameter, an axial hole I4 through the sleeve to receive the nozzle liner 9, an annular recess I5 to receive the flange of the nozzle liner, an internal thread I6 of larger diameter than the hole I4 thatv is fitted to a thread I1 of the tube 6, and an annular recess I8 near its rear end containing a rubber ring I9 that clamps against the tube 6 when sections 6 and 5 are screwed together, effectively brushing the thread free from sand and dirt. The recess I8 has one or more holes 20 extending radially outwardly from its circumference, which fit over one or more knobs 2I on the circumference of the rubber ring I9, thereby forcing the ring I9 to revolve with the sleeve 5. The discharge nozzle 9 is of substantially cylindrical section with an external annular ridge 22 near its center and a cylindrical axial hole 23 extending through it.

The hole 23 is tapered outwardly and rearwardly from a point near its rear end. The discharge nozzle 9 is preferably made of rubber or other resilient material since these materials being resilient, are much more resistant to abrasion than are metals. Disposed within the recess I5 and held against the outer end of the tube 6 is the ridge 22 of the nozzle liner SI;`

therefore, it will be seen that the nozzle liner 9 will not be forced from the gun by the projected abrasive. The wet sand is brought into the gun through a hose connection 24 which opens into the lower side of the chamber I3. Therefore, it will be seen that the course of the sand is through the hose connection 24, chamber I3 and nozzle 9 only, and since the movement of the sand is not rapid until it starts flowing through the nozzle 9, wear is largely restricted to this latter part.

The middle nozzle I0 has a cut-away forward section of reduced diameter, an ain'al hole 25 of varying diameter, being smallest at a point somewhat forward of its center; it tapers from this point outwardly in both directions.

Axiaily through the rearnozzle II is a hole 26 which tapers outwardly and forwardly from a point near the forward end of the nozzle. The external forward surface of the nozzle II tapers at 21 inwardly and forward from about the same position longitudinally that the internal taper begins. The front of the nozzle II is somewhat behind the rear of l the nozzle I0, forming a chamber I2 between the two in the tube 4. A needle valve 38 of well known design is screwed into a threaded opening 39`leading into the chamber I2 so that by adjusting this valve 38 varying ainounts of air can be allowed to flow into the chamber I2.

Connected with the tube 8 at its rear end is the section 29 of irregular shape containing the inlet 4I for water under relatively high pressure, having at its outward end a threaded section 42 for connecting the water hose.

Extending rearwardly through the section 29 is the chamber 43 containing the water inlet valve 44, provided with a knob 96. This valve is of well known design excepting that it has a novel means for sealing the valve stem 45 consisting of two circular washers 46 and 41 that fioat on the valve stem 45 and contain a quantity of packing substance 48 between them. When the water pressure builds up on the forward side of the washer 46, it moves it rearwardly and compresses the packing 48, since the rear washer 47 is held in place by the forward face of the valve gland 49. This compression of the packing 48 forces it against the valve stem 45 and against the cylindrical surface 5U. Therefore, manual adjustment is avoided and the greater the water pressure in the gun, the tighter the packing is compressed, the parts being so proportioned that the water pressure is always sufficient for sealing. With this Varrangement rotational friction on the valve stem 45 is always at the minimum for the pressure of the water against which the seal is maintained.

The above working parts of the gun are enclosed within the casing which consists of two main parts. The part I is of irregular shape so formed as to have a cavity 5I to take the working parts of the gun. A projection 2 extending downwardly near the front of the gun covers the sand hose for a short distance and serves as a handle to be held in the left hand, and a projection 3 extending rearwardly behind the working parts of the gun is to be held in the crook of the right arm. By thus holding the gun, the recoil in operation is easily absorbed without discomfort. A cover plate 52 is held to the case I by means of screws 53, effectively enclosing the working parts of the gun and holding them rigidly in place by means of the pressure of bosses 54 on a ridge 28.

In Figs. 3, 4 and 5, the sand feeder 55 consists of a cap 56 provided with a downwardly extending axial tube 51 through which sand is drawn to the hose and thence to the gun. Surrounding this tube is the tube 58 closed at the bottom by the cap 59 and at the top by the cap 56, having a plurality of holes 60 arranged radlally'around ,it near the lower end through which the sand and water mixture is drawn. Surrounding this tube 58 is the tube 6I closed at the bottom by the base 62 and sealed against the tube 58 at the top by the cap 63. Arranged radially around the tube 6I are a plurality of holes 64 somewhat closer to the top of the feeder than the holes 60.

Located vertically between the two rows of holes 60 and 64 and inside the tube 6I but surrounding and those in the inside tube 60 are still smaller.

It will also be noticed that as the sand and water mixture fiows inwardly toward the tube 51, it also flows downwardly since eachv successive row of will seep through the holes 64 and fall on the l0 baille plate 65, and since the holes 61 in the baille plate 65 are spacedbetween the holes 64 in the casing, only a very small amount of sand will fall through these holes 61 into the bottom' of the feeder. Consequently, when the machine is at 115 rest the lsand or other abrasive will not pack around the inlet tube 51.

When the gun is put into operation the suction on the tube 51 draws thewater from the feeder which sets up a current throughthe holes 64, 61 and 60 and draws a slurry of abrasive and water from the tank 68 through these holes and up through the tube 51 to the sand hose and gun. The holes 60 are made small so that the mixture has to move rapidly through them, thereby setting up the necessary current while the holes 64 are much larger so that the sand coming from the sand tank 68 moves relatively slowly into the feeder, thereby preventing a cone to the surface A forming around the feeder.

80 The'cap 56 has av connection 69 with an outside water supply communicating with the chamber between theA tubes 58 and 51. This water supply is controlled by a valve 10 and is used for flushing sand from the feeder, hose,

and gun'.

In Fi'g. 5 the feeder 55 is shown in a sand tank 68. It is connected with the gun by the hose 1| and with a water supply by the pipe 12. In the tank and surrounding the feeder is the wet sand 40 13. The tank 68 is covered by a platform 14 on which the operator can stand and to which the projected abrasive and abrasive such as core and moulding sand out or cleaned from the castings is washed by the water from the gun after being projected from the gun. The platform 14 is provided with holes 15 through which the sand and water mixture runs into a hopper 16 of a sand classifier 86. n the hopper 16 of the sand classifier is provided a screen 11 sloping toward a sludge tank 18 which is separated from the sand tank 68 by a partition 19. Thisl screen allows the sand, water and sludge mixture to pass through into a chamber 80 while rejecting larger particles downwardly through a. trough 8| and into the sludge tank 18. Communicating with the chamber 80 is a downwardly extending passageway 82 which is open at its bottom to an upwardly extending passageway 83 adjacent thereto. The top of the passageway 83 communicates with a water and sludge trough 84 which slopes downwardly and empties into the sludge tank 18. The bottom of the passageway.

83 has an opening 85 in communication with the inside of the sand tank 68. .f

In operation the sand, water and sludge mixture runs through the holes 15 inthe platform 1d and on to the screen where the large particles are separated from the `mixture and projected downwardly through the trough 8| and into the sludge tank 18. The sand, water and sludge mixture, freed of the large particles, ows through the screen, downwardly through the chamber and passageway 82 and into the passageway 83. From here the water carrying 75 the sludge iiowsv upwardly through the passage-J way 83, downwardlyfthrough the trough and into the sludge tank 18.

Since the water flowing upwardlyin the passageway 83 does not move rapidly enough to carry along the heavier abrasive particles in suspension, these particles settle out and drop through the opening 85 into the sand tank 68 from where they are recirculated through the sand feeder 55, hose 1| and back to the gun.

In the sludge tank 18 the fine sludge and large particles settle and the relatively clear ,water overflows through the outlet 81 and passes int thelsewer.

The pressure in the water hose leadingto the gun is relatively high, in Ithe nature of 700 to 1000 pounds to the square inch, which causes the hose to become more or less rigid. Consequently, it is preferred'to incorporate a swivel joint between the hose and gun. The swivel joint, Fig. 2, consists of three sections |00, |0| and |02. Section |00 has an external thread |03 on its forward end to iit the gun opening 42 and an axial hole |04, with an internal thread toward the rear end to join it to a stem |05 of the part |02.l Part l0| hasarcylindrical recess |06 with a thread |01 in the rear to couple with the water hose, an annular face |08 at the bottom of the recess and an axial hole |09 that closely fits the stem |05. Connecting the two sections |0| and |00 is the part |02 which has a long cylindrical stem |05 with a thread on its'forwaidV end to fasten rigidly to part |00 by means of the thread 'in the hole |04, an axial hole H0, and a thickened section at. its rear to t the recess |06 with two annular faces and ||2. Between the annular4 faces |08 and ||2 are two washers I|3 and H4 that t closely inside the recess |06 and around the stem |05 having between them a quantity of packing l I5. When the water pres-J compressing the packing ||5 and forcing it outwardly against the wall of the recess |06 and inwardly against the stern. The Size of the annular face is so proportioned that the necessary sealing action is obtained while allowing as much freedom of motion to the coupling as is consistent. The greater the pressure against the face the tighterthe packing will be compressed, and the more tightly the coupling will seal against leaks. Consequently, no tightening or other adjustment is necessary in orderto insure against leaks and still obtain freedom of movement.

The operation of the machine is as follows: When the high pressure water hose and sand hose are connected to the gun, the operator grasps the handle 2 in his left hand, holds the stock 3 in the crook of his right'arm and opens the water valve 44 by turning the knob 90. Thewater flows through the opening 4|, past the valve 44 and through the rear nozzle It comes out of this nozzle as a jet which expands somewhat before entering the opening of the nozzle I0. The size of the opening in nozzle l0 is such that the water stream lls it without producing any back pressure. Consequently, since the diameter of the stream leaving the chamber E2 is larger than the diameter of the stream entering the chamber, a depression in air pressure is produced in the chamber l2. Therefore, when the needle valve 38 is opened, air will flow into the chamber |2. This air is drawn' along with the water stream and incorporated in it in the form of line bubbles. Since the needle valve 38 does not admit as much air as the water stream will take up, the air in the chamber l2 is always -below atmospheric pressure; consequently, when this rareed air is incorporated into the water stream in the form of bubbles, these bubbles are of expanded air. When the jet of water and incorporated rarefied air is projected from the middle nozzle I into the front nozzle 9, an additional vacuum is produced in the chamber I3, drawing the sand and water mixture from the sand tank through the feeder 55, hose 1|, and coupling 24 into the chamber i3, where it is intimately incorporated with the stream of water and rareed air, the rarened air aiding the mixing of the sand with the stream. Thus, when the stream is projected from the nozzle at great force, it consists of an intimate mixture of water, sand and rarefied air bubbles..

The normal tendency of a stream of water when projected from a nozzle is to begin'to expand and disintegrate as soon as it leaves the nozzle. However, in this stream the tendency to expand is counteracted by the atmospheric pressure around it. That is, as soon as the stream leaves the nozzle 9, theatmosphericpressur'e around it collapses the air bubbles incorporated in the ,\stream, thereby having a. tendency to narrow the stream, the result being that the mixture is projected for a considerable distance as a thin pencil-like jet which has a much greater abrasive action than would be true of an expanded stream. However, if an expanded` stream is required for certain kinds of work, it is only necessary to close somewhat the needle valve 38, since by not allowing rareed air to be incorporated in the stream, the stream expands normally on leaving the gun. Consequently, by merely adjusting the valve 38, the operator can control the character of the stream Within Wide limits.

After the abrading stream Vstrikes the work it runs to the floor, back through-the holes 15 in the platform 14, through the sand classifier 86 .where the large particles and sludge are separated from the abrasive as previously described, and into the sand tank 68. From there the water and sand mixture is sucked in through the holes 64, down through the holes 61, in through the holes 60, up through the tube 51, and back to the gun through the hose 1I.

When it is desired to put the gun out of operation for a while, the water valve 10 is opened, 'a1- lowing water to iiow into the chamber between.

this chamber back through the holes 60, 61 and' 64 into the sand tank and also up through the tube 51 to the gun, thereby cleaning the feeder, hose and gun o'f sand. When clear water comes out of the nozzle 9, the apparatus is cleared oi sand and the valve 10 may be closed.

When it is desired to put the gun back into operation it is only necessary to open the valve 44 as usual and in a few seconds the system will be filled with sand again.

The invention having been set claimed to be new and useful is:

l. An abrading gun comprising an elongated body member with a water intake at one end and a discharge nozzle at the other end of said body member for projecting a fluid stream, a rear nozzle Within the body member forwardly of the water intake for creating a high velocity water stream within the body, an intermediate nozzle within the body member between the rear nozzle and the discharge nozzle, said intermediate and rear nozzles having their bores in axial forth, what is f 'l bancaria? vsand slurry to the chamber around the discharge end of the intermediate nozzle under the influence of suction created within said chamber, and means for admitting air to the chamber surrounding the discharge end of the rear nozzle i'or entrainment in the water stream in advance of the supply of sand slurry to the stream.

2. An abrading gun comprising a body member having a liquid intake end and a fluid discharge end for projecting a. stream oi iluid, a nozzle forming the iluid discharge end, spaced axially aligned nozzles within the body member having chambers around their discharge ends. means for feeding a sand slurry to the forward chamber, 'and adjustable means for admitting regulated amounts of air to the rearward chamber for varying the degree of vacuum in the last said chamber, and the degree of rarefication of the air entrained in the projected stream.

3. In a hydraulic labrading 'gun a. system of three nozzles in axial alignment, the rear nozzle and the middle nozzle having chambers around their discharge ends, and adjustable means to admit controlled amounts of air to the chamber around the discharge end of the rear nozzle.

4. In a hydraulic abrading gun, a system of three nozzles in axial alignment the rear nozzle and middle nozzle having chambers around their discharge ends, means Ai'or venting the chamber around the discharge end of the rear nozzle to `the atmosphere, and valve means in said vent to resist the passage of air therethrough.

5. In a gun of the class described, means for automatically `cleaning the thread .of the gun body whenever the nozzle is screwed on the gun, said means consisting of a threaded nozzle containing an annular recess at the outside end of the thread, and an annular rubber ring -in the bedded in the abrading material, said supply pipe extending into said Acylinder in spaced relation to the inner periphery thereof, and a baffle plate within said cylinder and having openings through which abrading material passes to the 'supply pipe, all for the purpose of preventing packing of sand in the supply pipe.

.7. In combination with an abrading gun, means for feeding the abrading material to a supply pipe, said means comprising an apertured chamber gto be embedded inthe abrading materlal, said supply pipe extending into said chamber, and one or more apertured chambers inside the iirst said chamber so arranged that the abrading material must pass through the last said chamber or chambers before reaching the supply pipe, for the purposeI of preventing packing of sand in the supply pipe.

i 8. A feeder of the class described consisting of a sand pipe; a shell around the sand pipe opening, said shell being closed at the bottom and top and having a plurality of holes around the bottom; a second shell around the rst shell, said second shell being closed at the bottom and top, and having holes near the bottom; these last said Y holes having a greater total area andbeng higher up than the holes in the iirst named shell.

9. A feeder of the class described consisting of a sand pipe; a shell around the sand pipe opentop andhaving a plurality of hols around the and means to admit abrasive particles mixedl with water between the middle nozzle and the bottom; a second shell around the first shell, said second shell being closed at the bottom and topiand having holes near the bottom, these ,last said holes having -a greater total area land being higher up than the holes in the first named shell; and a connection to an outside water supply between the first and second shells for washing out the feeder, sand hose and gun.

10. The method of preventing packing in a sand hose and sand feeder conveying a sand and water sluurry to a hydraulic blast gun which comprises admitting clear water under pressure to the system at' such a point that sand is forced backwardly from the feeder and forwardly from the hose and gun, said water under pressure being admitted before the vblast gun is shut off and its admission being continued until no more sand is projected from the blast gun, the gun then vbeingy shut off before the clear water is shut oi.

11. In a hydraulic sand blast gun, a gun body provided with three nozzles in tandem, means to project a high pressure liquid stream through said three nozzles, valve means to admit air between the rear nozzle and the middle nozzle,

front nozzle. l

12. The combination with the supply pipe of a hydraulic abrading gun, of means for feeding a slurry of abrading material to the supply pipe, 4said means Acomprising an apertured chamber adapted to be embedded in --the wet abrading material, said supply pipe extending into said chamber in spaced relation to the inner periphery thereof, and means to admit a substantially sand free uid to the feeder between the supply pipe land the chamber wall for washing abrading material from the supply pipe and chamber.

13. In a device of the class described, a gun, a sand supply system comprising a sand supply conduit connected to said gun, a feeder connected to the conduit, said feeder adapted to be inserted in a tank of wet sand to feed a sand slurry therefrom; and means to admit a substantially sand free uid to the feeder in such a position that sand is washed from the feeder, supply conduit, and gun.

14. In a hydraulic sand blasting device, the combination comprising: an elongated body member having water intake and discharge ends,

means to project a high pressure liquid stream f through said body member, needle valve means to admit controlled amounts of air to said body member for incorporation in. the liquid stream passing therethrough, and means to admit a sand.slurry to said body member for incorporation in said liquid stream subsequent to the incorporation of the air in said stream.

15. The method of controlling the-spreading of a projected liquid jet which comprises the steps of mixing rareed air with `the liquid before it is finally projected as a jet and adjusting f the amount of said air that is mixed with the liquid.

16.- 'I'he method of projecting abrasive material with a relatively non-compressible fluid carrying medium which comprises the steps of mixing with the relatively non-compressible fluid carrying medium a controlled amount of ext pansible uid to provide a relatively porous fluid mixture, then separately mixing abrasive material with the porous uid mixture and projecting the mixed abrasive and porous fluid.

` 5 l 17. The method of projecting abrasive material comprising the steps vof subjecting a supply of liquid carrying medium to high pressure, restricting the now of the saidiliquid carrying medium to a high velocity jet, passing said jet through a. chamber to produce a partial vacuum in said chamber, admitting air to said chamber through a restricted orifice and incorporating said air in the liquid stream, restricting and projecting the liquid canying medium as a second high velocity jet, admixing granular abrasive with the second high velocity jet, and projecting the liquid carrying medium and admixed air and abrasive as a high velocity jet.

18. The method of projecting abrasive material comprising the steps of subjecting a supply of water to high pressure, restricting the iow of water to a high velocity jet, restricting. the ampunt and-pressure of air surrounding the jet so as to admix with the jet a lcontrolled amount of rarefied air, restricting and reprojecting water and admixed air through a slurry of admixed water and granular abrasive, and projecting the water, air, and granular abrasive as aphlgh veloclity jet.

19. The methodof cleaning or cutting with an abrasive material which comprises the steps of admixing liquid with a supply of granular abrasive, subjecting a liquid carrying medium to high pressure, projecting the liquid carrying medium as a. high velocity jet, admixing air with the projected jet of liquid carrying medium, repojecting the liquid carrying medium and admixed air as a. second high velocity jet, utilizing the force of the second high velocity jet to pump admixed liquid and granular abrasive, entraining the admixed liquid and granular abrasive in the second high velocity jet, and projecting the liquid carrying medium and entrained granular abrasive and air as a third high velocity jet. i 20. The method of cleaning or cutting with an abrasive material which comprises the steps of admixing liquid with a supply of granular abrasive, subjecting a liquid carrying medium to high pressure,` projecting the liquid carrying medium asa high velocity jet, admixing air with the projected jet of liquid carrying medium, restricting and projecting the liquid carrying medium and admixed air as a second high velocity jet, pumping the admixed liquid and granular abrasive by the force of the second jet, entraining the admixed liquid and granular abrasive in the second jet, projecting the liquid carrying medium and entrained granular abrasive as a high velocity jet, and reclaiming and reusing the granular abrasive.

21. The method of cleaning or cutting with an abrasive material which comprises the steps of admixing liquid with a supply of granular abrasive, subjecting a liquid carrying medium to high pressure, projecting the liquid carrying litt medium as a high velocity jet, admixing air n with the projected jet of liquid carrying medium, restricting and projecting the .liquid carryi of admixing liquid with a supply of granular 6 i abrasive, subjecting a.l liquid carrying medium to high pressure, projecting the liquid carrying medium asa high velocity jet, admixing air with the projected jet of liquid canying medium, restricting and projecting the liquid carrying medium and admixed air as a second high velocity jet, pumping the admixed liquid and graniilax' abrasive by the force of the second jet, entraining the'admixed liquid and granular abrasive in the second jet, projecting the liquid carrying medium and entrained granular abrasive as a high. velocity jet, washing the' granular abrasive with the liquid carrying medium,- and reclaiming andV reusing the granular abrasive.

23. The method of cleaning or cutting with an abrasivmaterial which comprises the steps of admixingliquid with a supply of granular abrasive, subjecting a.v liquid carrying medium to high pressure, projecting the liquid carrying medium as a high velocity jet, admixing air with the projected jet of liquid carrying medium, restricting and projecting the liquid carrying medium and admixed air as `a. second high velocity jet, pumping the admixed liquid and granular abrasive bytheriorce of thesecond jet, entrainin g the admixed liquid and granular abrasive in the second jet, projecting the liquid carrying medium and entrained granular abrasive as a high 'velocity jet, washing the granular abrasive with the liquid carrying medium, screening, reclaiming and reusing the granular abrasive,

and draining off excess liquid from the reclaimed abrasive material.

24. In an abrading gun adapted to be utilized with a supply of liquid under high pressure so that said liquid provides a.l carrying and motivating medium for abrasive material, the combination comprising a body including three spaced and axially aligned nozzles and providing chambers at each end of the intermediate nozzle, a liquid input connection communicating with one of the end nozzles so that liquid is projected from each of the nozzles and through each of the chambers as a high velocity jet, an adjustable valve for admitting a controlled amount of air only to the chamber between the intermediate nozzle and said one oi the end nozzles for controlling the spread of the high a sand slurry into the chamber for entrainment in the said high velocity jet therein.

25. In an abrading gun adapted to be utilized with a supply 0f liquid under high pressure so that said liquid provides a carrying and motivating medium for abrasive material. the combination comprising a body including three spaced and axially aligned nozzles and providing chambers at each end of the-intermediate nozzlel a liquid input connection communicating with one of the end nozzles so that liquid'is projected from each oi the nozzles and through each of the chambers as a high velocity jet, two of said axially aligned nozzles having a larger opening therein than the preceding nozzle through which the liquid passes, an adjustable valve for admitting a controlled amount of air only to the chamber between the intermediate nozzle and said one of the end nozzles for controlling the spread of the high Velocity jet from the last nozzle from which the liquid is projected, and means communicating with the other of the chambers for introducing a sand slurry into the chamber for entrainment in the said high velocity jet therein.

26. The method of cleaning or cutting with an abrasive material which comprises the steps of admixing a liquid with a supply of granular abrasive, subjecting a liquid carrying medium to high pressure, prrjecting the liquid carrying medium as a high velocity jet, utilizing the force of the high velocity jet to pump the admixed liquid and granular abrasive, entrainirig the admixed liquid and granular abrasive in the high velocity liquid jet, and projecting the liquid carrying medium and entrained granular abrasive as a cleaning and cutting jet.

27. The method of producing a high velocity.

LESLIE L. v'I'IIEiRELL

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