US2723498A - Abrasive blasting machine - Google Patents

Description

NOV. 15, HASTRUP ETAL ABRASIVE BLASTING MACHINE Filed April 9, 1953 5 Sheets-Sheet l INVENTOR. J Herman Hastrup I, BY Dale E Pinkerton ATTORNEY Nov. 15, 1955 H. HASTRUP ET AL ABRASIVE BLASTING MACHINE Filed April 9, 1953 5 Sheets-Sheet 2 '54 INVENTOR.

5s Hermon Hastrup BYDole F. Pinkerton 55 I ATTORN EY H. HASTRUP ET AL 2,723,498

ABRASIVE BLASTING MACHINE Nov. 15, 1955 Filed April 9, 1953 5 Sheets-Sheet 3 Herman Hosirup ByDaie E Pinkerton ATTREY Nov. 15, 1955 H. HASTRUP ET AL 2,723,498

ABRASIVE BLASTING MACHINE Filed April 9, 1953 5 Sheets-Sheet 4 INVENTORS DALE F. PINKERTON HERMAN HASTRUP ATTORNEY Nov. 15, 1955 H. HASTRUP ET AL ABRASIVE BLASTING MACHINE 5 Sheets-Sheet 5 A 1 f M Filed April 9, 1953 Inf/AAI INVENTORS DALE F. PINKERTON HERMAN HASTRUP BY fl y mw/ 4 a ATTORNEY United States Patent Ofiice ABRASIVE BLASTIN G MACHINE Herman Hastrup, Lanikai, Territory of Hawaii, and Dale F. Pinkerton, San Francisco, Calif.

Application April 9, 1953, Serial No. 347,858 32 Claims. (Cl. 51-8) (Granted under Title 35, U. S. Code (1952), see. 266) The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

This application is a continuation-in-part of abandoned but copending application Serial No. 130,822 filed December 2, 1949 for Abrasive Blasting Machine.

This invention relates to improvements in abrasive blasting machines and more particularly to such machines of the portable type used for removing paint, rust or other coatings from metal or other surfaces by applying a blast of abrasive particles thereto.

It is an object of the invention to provide a blasting machine of such light weight as to be readily portable and used by a single operator.

It is an important object of the invention to provide an abrasive blasting machine which is portable in its entirety as a single unit; and which is complete in itself so as to require only a single connection to a source of air under pressure for manual use in cleaning operations.

Another object of the invention is to provide a portable blasting machine in which the abrasive for cleaning a surface is recirculated in the machine.

An important object of the invention is to provide a completely portable abrasive blasting machine of a type described which is extremely compact and light so that the whole machine can be worn by a single operator, preferably with a suitable harness; the elements of the machine being designed, arranged and carried so that the single operator can easily handle the machine for cleaning both regular and irregular surfaces, vertical and horizontal surfaces, and surfaces awkward or diflicult to reach as Well as those easy to reach. To this end, the machine comprises a novel operating head or nozzle unit which is readily manipulated manually against the surfaces.

A further object of the invention resides in providing a portable blasting machine with an improved operating head, or nozzle unit, having a work piece contactor of sufficient resiliency for smoothly contacting the surface being treated while containing sufi'lcient flexibility to adapt itself to any rough protrusions residing on the surface of the object being treated.

A further object of the invention is the provision of an'improved operating head for the blasting machine which incorporates abrasive supply and returns channels therein, the return channel having sufiicient suction effect to draw in the spent abrasive particles and the dirt particles or debris dislodged from the surface being cleaned. 4

Still another object of the invention is to provide a completely portable abrasive blasting machine having a nozzle unit in the form of an operating head to which an air stream under pressure can be supplied for providing all the man-made power needed to operate the whole machine. In accordance with the invention, the head has simple improved means therein providing a blast nozzle and an eductor nozzle to which the air is passed. In a 2,723,498 Patented Nov. 15, 1955 preferred embodiment of the invention, the supply air is divided into two streams by a manually controlled valve in the operating head. One stream passes to the blast nozzle for drawing abrasive particles from an abrasive container means or unit of the machine and for carrying the abrasive particles to the surface being treated. The other stream passes through the eductor nozzle for forcing the spent abrasive particles and the debris, including the blasted off surface or dirt particles, through a return channel in the head. The channel leads to additional elements of the portable blasting machine. These additional elements comprise a separator means or unit for separating the dirt particles from the abrasive particles, 3. short hose connecting the return channel to the separator unit, the abrasive container unit to which the separatedout abrasive particles pass, and a short feed conduit or hose for delivering these particles from the container unit back to the operating head for reuse. The energy supplied in the nozzle unit to the spent particles and debris is enough to pass them through the separator unit for separation, and to deliver the cleaned abrasive particles to the container unit therefor for reuse. Consequently, the portable machine, although small, has a complete path in which abrasive particles are recirculated for use over and over again, and by means of the single energy source comprising air under pressure.

Other objects and features of the invention will be readily apparent from consideration of the following specification and claims relating to the annexed drawings wherein:

Figure 1 is a perspective view of a portable abrasive blasting machine constituting a preferred embodiment of the invention as used on a'ceiling by an operator indicated in dotted lines;

Figure 2 is a perspective view of the machine as applied to a vertical surface, such as a wall, and also sup ported by an operator indicated in dotted lines;

Figure 3 is a sectional view in elevation of the nozzle unit of this machine, taken along lines 33 of Figure 2, with arrows added to show the path for air passing through its blasts and eductor nozzles, the valve therefor and the return channelwhich directs particles of abrasive and debris to the return conduit leading to the separator unit of this machine.

Figure 4 is a section of the nozzle unit taken along lines 44 of Figure 3, showing the valve operating means;

Figures 5, 6 and 7 are sectional views taken through the valve for difierent degrees of valve stem rotation, Figure 5 indicating closure, Figure 6 indicating eductor opening only, and Figure 7 indicating both blast and eductor opening;

Figure 8 is a perspective view of a modified work piece contactor adapted for use on one end of the operating head of the machine;

Figure 9 is a section on lines 99 of Figure 2 showing the particle separator unit and the abrasive container unit of this machine;

Figure 10 is a cross section of the abrasive container taken on lines 10-10 of Figure 9;

Figure 11 is a detail section showing a second modification of a work piece contactor adapted for use on one end of the operating head of the machine;

Figure 12 is a perspective view of a modified form of a portable abrasive blasting machine embodying principles of the invention;

Figure 13 is a vertical sectional view of the separator and container units of the embodiment of Figure 12, taken on lines 13-13 of Figure 12;

Figure 14 is a horizontal section taken on lines 1414 of Figure 13;

Figure 15 is a longitudinal sectional view taken on lines 15-45 of Figure 12 showing details of the operating head or nozzle unit of the embodiment of Figure 12;

Figure 16 is a sectional view in elevation showing details of the inside of the central part of the operating head or nozzle unit of Figure 15;

Figure 17 is a horizontal view taken on lines 17-17 of Figure 15 showing details of the air supply valve of the operating head, the valve being shown closed; and

Figure 18 is a sectional view taken on lines 1818 of Figure 17 showing the valve operating mechanism with the valve in open position.

Referring now to the drawings and particularly Figures 1-11, in which like reference numerals designate like parts throughout the various views, there is disclosed a blasting machine consisting of three main parts or units; a nozzle unit or operating head 15, a separator unit 16 and an abrasive container unit 17.

Figures 1 and 2 illustrate the relative location of these units with respect to one another. Broadly stated, the machine functions by supplying air under pressure to the nozzle unit for blasting and suction purposes, supplying abrasive such as sand or steel grit from the container to the nozzle through nozzle suction, and utilizing the separator to screen out abrasive particles for recirculation to the blast nozzle, a minimum of conduit being used in the machine for these purposes.

The nozzle unit 15, Figure 3, which is adapted to be placed against a corroded surface, comprises a casing 22, a cross-shaped valve block 23 welded or otherwise secured within the casing 22, a blast nozzle 18, an eductor nozzle 19, a control valve 20 for the nozzles, and an injector nozzle 21 in line with the blast nozzle.

The block 23 is formed to receive the nozzles 13, 19 and 21 in axial alignment (vertical in Fig. 3), and to receive the valve 21 which controls the supply of air to the nozzles. To this end the block 23 is provided with a lateral bore 14 extending horizontally therethrough and with a pair of vertically positioned openings on its upper and lower sides. The upper and lower openings are each internally threaded and respectively have screwed therein, in vertical alignment but extending in opposite directions, the eductor nozzle 19 and injector nozzle 21. Axially aligned with the injector nozzle 21, the block 23 has a threaded opening of increased diameter for receiving blast nozzle 18.

The lateral bore 14 is provided with a chamber 13, Figure 4, and is internally threaded for receiving any suitable hose adapter 24 and attached rubber hose means 25 which supplies air under pressure to the nozzle unit 15. The other end of the bore is closed by a hollow screw plug 26 which also constitutes a tubular bearing for valve pin 27. As shown, the plug 26 is screw threaded in the transverse plug opening and presses upon an annular ring 28 formed in the valve block 23 through a gasket 29 positioned therebetween.

The valve 2 as better shown in Figures 4 and 5, comprises a hollow cylinder having opposite ports 33 and 34 therein, port 34 being approximately twice the length of port 33. Block openings 31 and 32 are formed in the block 23 above and below the valve ports 33 and 34; and adjustment of the relative position of these valve ports and block openings is made by the valve pin 27 as controlled by valve handle 34' on the outer end of the valve pin. Referring to Figures 3, 5, 6 and 7 the various functions of the valve 21 may be explained. In Figure 5, communication between openings 31 and 32 is shut off by the valve wall. In Figure 6 communication is made between the block chamber 13 and opening 31, so that air under pressure may be supplied to the eductor nozzle 19. In Figure 7 communication is established from chamber 13 to both upper and lower openings 31 and 32. By this arrangement, it is seen that if the valve is rotated in the sequence of Figures 5, 6 and 7 as indicated by the direction arrows, air under pressure is always passed to opening 31 bef e being released through opening 32, and that valve 20 is adapted to simultaneously shut off the flow of air supplied through openings 31 and 32. The blast is stopped by reversing the valve rotation resulting in first cutting off the supply of air to the injector nozzle 21 and the blast nozzle 18 and then to the eductor nozzle 19, thus assuring a complete removal of debris from the work area, as will be more fully described hereinafter.

As aforementioned, the eductor nozzle 19 is mounted in extension of block opening 31 by a screw thread connection. Beneath the opening 32 and in line therewith is the air injector nozzle 21, the tip of which lies in a reduced pressure region or chamber 41 formed in the bottom portion of valve block 23. A circular inlet, terminating in a port 42, is formed in the block 23 and casing 22 through which abrasive material can pass to chamber 41 where it mixes with air flowing from injector nozzle 21 prior to its delivery through blast nozzle 18. The blast nozzle 18 is subtended from the chamber 41 and the former is provided with an annular flange 43 which coacts with shoulder on the valve block 23 for forming a substantially air tight fit and is held in place by a screw plug 45 on its lower side. The blast nozzle has a central duct 46 communicating with the chamber 41 adjacent port 42 at its inner end and terminating in a flared tip outlet 46a at its outer end.

The lower portion of the nozzle unit 15 comprises a pair of spaced concentric tubular casings 47 and 49. The inner casing 47 is attached to the lower end of the valve block 23 and extends downwardly therefrom beyond the blast nozzle 18 to form a blast chamber 48 below the blast nozzle, as better shown in Figure 3. The outer cylindrical casing 49 is spaced from the inner casing 47 so as to form therewith a substantial annular channel or space 51) between the casings to provide a cylindrical shell passageway for return flow of abrasive and debris particles as will be made clear hereinafter. This second and outer casing 49 is formed in extension of casing 22 closely surrounding valve block 23, the attachment therebetween consisting in an annular ridge 52 at the lower outer edge of the casing 22, and an overlying groove 53 at the adjoining end of casing 49.

The lower ends of casings 47 and 49 are bridged by the tubular coiled spring screen 51, the spaces between turns serving to limit the size of debris particles and operating to break up the larger particles, so that only abrasive and debris granules of limited dimensions pass through the screen. In order to provide a passageway around the outer end of casing 47, to and through screen 51 and into space 50, a downwardly protruding terminal band or adapter 54 is attached as by twine 60' and a bead groove connection 61 to the lower edge of outer casing 49 so as to extend below the lower edge of the inner casing 47. The band 54 has a yieldable contact coil spring 55, deeply seated in its bottom so as to bring the edge of the band 54 beyond the outer edge of the casing 47 and close to the working surface to be cleaned. Such a surface is indicated at 56. Thus, a constricted passageway is formed around the end of casing 47, when the nozzle is applied to a plane work piece. While rigid material may be used for the casings 47, 49 and band 54, the use of yieldable elastic material such as rubberized fabrics has been found desirable in that casings of these fabrics readily conform and adjust to the surfaces being cleaned, which may vary widely in smoothness and angularity.

The block casing 22 is appropriately apertured to receive the hose adapter 24 and the screw plug 26. Also above the block 23, as shown in Figure 3, the casing 22 is tapered approximately to the level of the tip of eductor nozzle 19 and then continued as a cylindrical section 57 to form a reduced pressure region or suction chamber 58 which communicates with the cylindrical channel 50 between casings 47 and 49. The taper of casing 22 conforms to the shape of the discharge end 40 of nozzle 19. Communication between chamber 58 and channel 50 is made by way of spaced axial edge channels 59 (Figure 4) formed by the coaction of the inner wall of casing 22 and the cut-away section of valve block 23. Tubing 60 is connected at one end to the top of casing 22 and at the other end to separator unit 16 which will now be described.

As shown in Figure 9, the separator unit 16 includes chiefly: a separator 65 and a dust bag 66 shown broken away in the figure. The separator is constructed as a relatively Wide hollow cylindrical body member 67 having a flat back 68 and an outwardly converging front element 69 terminating in an annular edge groove 70 from which a short tube 64 extends inwardly. In this groove 70, a wire ring 71 removably clamps the neck end 72 of the dust bag 66 which is made of conventional airpervious material permitting escape of air under pressure but retaining small particles of grit, abrasive or debris as received from separator 65. The separator inlet 74, Figures 2 and 9, is directed tangentially into the body member 67 of the separator 65, so that the mixed air, abrasive particles and debris particles which enter the separator through tubing or hose 60 tend to move outwardly along the inside of the body member 67. The heavier abrasive particles are thrown outward by centrifugal action. The separator 65 also includes an outlet port 75 which is approximately diametrically opposite the inlet port 74, into which the heavier abrasive particles pass. The lighter particles continue around the separator chamber moving toward and through the central dust outlet 76 into the dust bag 66 where the air escapes leaving the debris for removal as desired.

The separator outlet 75 for the separated-out abrasive particles is connected to a short connection or passageway joining the separator and the container. This connection includes a shortneck or conduit 76' and a pivot joint 78. The joint 78 includes a tube having a flared section 80 and a cylindrical section 81 as shown in Figure 9. The flared section 80 has a Wall which is formed with an opening 82 and this wall is placed across the base end of conduit 76' with the opening 82 in alignment therewith. The enlarged end of the flared section surrounds the container inlet 77.

The abrasive container 17 is approximately kiteshaped with an enlarged top portion tapering down to a constricted base having a loading opening at its bottom which is closed by a removable rubber cup 83. The inlet tube 77 is fixed near the top of the container on one side thereof. An L-shaped pipe 84, having transverse section 85 and axial section 86, is supported by spider 87 inside the container for centrally locating the pipe section 86 in the container. The lower end of the pipe terminates near the cup 83, and the transverse section 85 passes centrally through the tube 77 and terminates in a screw thread connection with joint section 81. An elastic gasket 88 is placed on tube 77. The yield of gasket 88 and the pitch of the thread junction of pipe section 85 and joint section 81 are such as to permit pivotal adjustment of the abrasive container through an angle of at least 180 with respect to the separator 65 of the separator unit 16, without disturbance of the gasket seal, to accommodate the apparatus for floor, wall or ceiling blasting.

The container pipe 84 has connection with the port 42 at the injector 21 by means of a flexible hose 89, there being a coupler 90 at one end, screw threaded to conduit section 81, and a coupler 91 at the other end communicating with port 42 of the chamber 41 in the nozzle unit 15. Thus suction developed in chamber 41 by the action of ejector nozzle 21 is made effective at the open lower end of the pipe section 86 at the base of the container 17 and abrasive is thereby drawn from the container, through pipe 84 and hose 89 and into chamber 41 where it is merged with the air flowing through injector nozzle 21, prior to delivery through the blast nozzlelS.

The operation of the machine will now be described, it being assumed that a supply of abrasive, such as steel grit, is in container 17. Air pressure at suitable pressure,

such as pounds per square inch, is supplied to the chamber 13 of the bore 14 leading to the inside of valve 20. The valve, which is normally closed as in Figure 5, is then manually rotated through handle 34' in the direction indicated, approaching the setting of Figure 6. This setting opens communication between the valve center cavity and the eductor nozzle 19 and air is blown forcibly therethrough creating a pronounced suction effect at the base end of nozzle unit 15. Atmospheric air surrounding nozzle unit 15 is drawn past the adapter 54 and serves to purge the nozzle unit of any debris or grit contained in the passages thereof While simultaneously conditioning the nozzle unit for the application of abrasive material.

The valve rotation is continued to the operating position of Figure 7, in which position the air under pressure flows through the injector nozzle 21 and blast nozzle 18, as Well as eductor nozzle 19. The ejector action develops a suction at the port 42 of chamber 41, drawing in abrasive from the container 17 which mixes with the air blast, the mixture forcibly passing through the blast nozzle 18 to the surface of the workpiece 56 to be cleaned. The ricocheting steel grit as well as particles of debris are drawn by the established suction of eductor 19 through the screen 51, large particles being broken by repeated impact on the screen wire and by ricocheting abrasive, and the resultant mixture carried by the air draft to the separator unit 16. Here the smaller lighter particles pass into the dust bag, while the larger heavier particles are whirled around the separator periphery and pass through outlets 75 and into the abrasive container unit 17 from which these particles can again be drawn into tube section 85 and hose 89; and thus the abrasive particles recirculate over and over again within the portable machine in a closed path comprising the bottom of the container unit 17, the tube 84, coupler 90, flexible hose or feed line 89, coupler 91, port 42, chamber 41, blast nozzle 18, blast chamber 48, the surface 56, the space 50, the chamber 58, tubing 60, inlet 74 of the separator 65, the separator 65, separator outlet 75, flared section 80 of the pivot joint 78, and back to the container unit 17 through inlet tube 75. It will be readily apparent that the upper portion of the abrasive container unit 17 is at a relatively higher air pressure than is its lower portion, because of the pressure of air leaving the eductor nozzle 19 and passing to the container unit. The lower portion of the container unit 17 is at the same time subjected to the relatively reduced air pressure at the open end of container pipe 84 which is connected to the reduced pressure region of the injector nozzle 21.

In order to preserve the proper relationship of the abrasive container unit 17 in vertical position so as to permit the ready use of the nozzle unit on floor, ceiling or wall, the container unit is manually adjusted. Such action is permitted by the pivot joint 78, its elastic gasket 88 serving to maintain the air seal for the extent of pivotal movement required. Thus the use of the screw thread attachment of the container to the separator joint is made feasible and extensive break-down and reassembly or" parts, or duplication of equipment is made unnecessary.

The workpiece engaging nozzle unit tip shown in Figure 3, which is formed of elastic turns of Wire coil 55 supported by flexible band 54, has been found practical for ordinary blast operations. However, modification of this particular structure may be desirable as shown, for example, in Figures 8 and 11. In Figure 11 the use of the two coil springs 22, and 93, respectively similar to coil springs 51 and 55, is continued but with minor modification in that the contact spring 93 is directly attached to the outer casing 49 and use is made of a retaining apron 94 attached to inner casing 47 for positioning spring 95 somewhat above spring 93, and for keeping the nozzle casings in properly spaced relationship. In this form the angle or ricochet for the particles is more abrupt than in the arrangement of Figure 3. Figure 8 illustrates the use of a brush 96 in place of the contact coils 93 and 95, the brush being supported by ring 97 and retained in position by the elastic support '8 overlying the bead 61 on the outer casing.

Referring now to the modification of Figures 12 through 17, there is shown a portable abrasive blasting machine which employs the same principle of operation as that above-described but differs considerably in the structure used for carrying out the operation. A modified operating head or nozzle unit and a modified separator and container means are also shown in these figures for effectively separating the abrasive material from the debris cleaned from a surface.

In the modified form of the invention of Figures 1217, the portable machine comprises a receptacle 110 comprising a combined separator and container means for the abrasive particles to be projected on the surface to be cleaned, an abrasive feed line or hose 111 through which the abrasive particles are drawn, an operating head or nozzle unit 112 to which air under pressure is fed by a detachable air supply line 112' for drawing the abrasive particles from the receptacle 110 through the feed line 111 and delivering them with great force against the surface to be cleaned, a return trunk or hose 113 from the nozzle unit for delivering the mixture of spent abrasive particles and debris back to the receptacle 110. An important feature of this modified form resides in the construction of the receptacle 110 which comprises a separator 114 to which the return hose 113 delivers the mixture, and a container 115. The separator 114 also comprises an air-pervious dust collecting sack 114'. In accordance with the invention, the separator 114 and the container 115 are combined into the single unit or receptacle 110 for further decreased weight and simplicity. Another important feature of this embodiment resides in the simplified nozzle unit.

As shown in Figures through 18, the nozzle unit 112 is formed of an outer casing and contains a globular air pressure chamber 117 therein which receives the air under pressure from the line 112' through a valve casing 118 which may be removably attached to one side of the casing of the nozzle unit 112, as indicated by screw threading in Figures 17 and 18.

The valve casing 1.18 includes a movable valve 119 for controlling the how of air from line 112' to the nozzle unit 112. The valve 119 is mounted to reciprocate in the casing 118 toward and from a valve seat 120. A valve stem 121 connected to the valve 119 slides through a plug 122 screw threaded or otherwise removably carried in the outer end of the casing 118. The valve stem 121 also slides through a stuffing box 123 mounted in the plug 122. A coil or other spring 124 wound in a suitable number of convolutions about the valve stem 121 abuts the valve 119 at one end and the plug 122 at the other end. This spring helix is under suitable load or compression biasing the valve 119 to a closed position against its seat 120.

The opening movement of the valve 119 is under the control of a handle lever 125 accessible to the hand of the operator, as shown in Figures l2, l7 and 18, and carried upon pivots 126 mounted in arms 127 which derive their support from the casing of the nozzle unit 112 or other suitable part. The upper end of the lever 125 terminates in forks 128 pivoted to the sides of a yoke 129 to which the outer end of the valve stem 121 is afilxed.

The valve casing 118 has a lateral extension 130 to which the air pressure line 112' is coupled and with which an air inlet port 131 communicates. When the valve 119 is open and away from its seat 120, air from line 112' passes through the valve casing 118 and into the air pressure chamber 117.

Below the air pressure chamber 117 is a nozzle block 132 having a Venturi throat composed of an inner convergent section 133 and an outer divergent section 134. An abrasive induction tube or nozzle 135 of smaller external diameter than the internal diameter of the air pressure chamber 117 extends through such chamber and has its inner abrasive delivery end located in the reduced pressure region or Venturi throat. The free end 136 of such tube or nozzle is shaped as to its outer surface in a manner complementary to the inner convergent section 133 of the throat in order to cooperate therewith in the manner of a valve to regulate and adjust the width of the air passage between this valve end 136 and the wall of the convergent throat section 133. The throat section 133 corresponds, in efiect, to the injector nozzle 21 of the embodiment of Figures 1-11; whereas the section 134 corresponds, in effect, to the blast nozzle 18 of the embodiment of Figure l-l 1.

For the purposes of adjustment the abrasive induction tube 135 is carried on a threaded plug 137 which is threaded for rotational and axial adjustment in the nozzle unit 112. A lock nut 138 is provided to preserve the adjustment.

The interior of the plug 137 is made with a smooth bore 139 opening outwardly and terminating at its inner end in a stop shoulder 140. The bore 139 is adapted to slidingly yet snugly receive the end of the abrasive feed line hose 111, which end will be of some flexible material which permits the line to be withdrawn from the bore and flexed in the manner indicated by the dotted lines in Figure 15 so that the then free and disconnected end of the feed line 111 may be inserted over a stud 141 carried upon the nozzle unit 112. The stud is preferably provided with a round head 142 larger in diameter than the internal diameter of the feed line 111, which will require the end of the feed line to be forcibly inserted over the stud, the flexible and resilient wall of the feed line 111 being outwardly displaced by the enlarged head 142. This will insure the free end of the feed line 111 remaining on the stud 141 until positively and forcibly removed therefrom.

The nozzle block 132 is screw threaded or otherwise detachably mounted in the casing of the nozzle unit 112 as shown at 143 in Figure 16. The mounting is shown to be made in a dependent neck 145 of the nozzle unit 112. An inner shoulder 144 of the nozzle block 132 may abut against the inner end of the neck 145. An outer shoulder 146 of the nozzle block 132 is spaced from an annular flange 147 to provide therebetween an annular groove 148.

As better shown in Figures 15 and 16, a casing or partition sleeve 149, preferably of a frustoconical form, is fitted to the inner end of the nozzle block 132 as an extension thereof. The inner bore of this casing or sleeve 149 is complementary to the outer divergent section 134 of the Venturi throat, and together therewith forms a progressively enlarging passage for the forcibly propelled abrasive and air. The outer larger end of the easing or sleeve 149 is open to discharge the abrasive and air against the surface to be treated. The neck 145, nozzle block 132 and inner casing or sleeve 149 have external diameters substantially less than the internal diameter of the nozzle unit 112 to provide an annular exhaust channel, space, or passage 150 for the abrasive, debris and air after performing the work of blasting. The adjacent internal wall or casing of the nozzle unit 112 which surrounds the sleeve 149 may be provided with a suitable liner 151 of hard rubber or other material resistant to abrasion. The sleeve 149 may be made of the same material and with sufficient flexibility and resiliency so that the annular recess 152 internally of the upper end portion thereof may be expanded to slip over the flange 147 at the lower end of the nozzle block 132 with the portion of the sleeve 149 lying above this recess 152 being inter-lockingly received into the annular groove 148 of the nozzle block 132. The upper end of the sleeve 149 will then abut upon the outer shoulder 146. it will be understood that the sleeve 149 may be attached to the nozzle block 132 in any other suitable manner.

The outer end of the nozzle unit 112 comprises a work piece adapter or hollow hood 153 of rubber or other resilient material having a confining lateral wall 154 which is inclined or tapered as to its external surface from a wider base at the inner portion of the adapter to a narrower section at the outer portion thereof where the adapter is provided with an opening 155 surrounded by turned back edges 156. The opening 155 is in alignment with the larger discharge end of the frusto conical division or partition sleeve 149 and spaced therefrom, being preferably of a slightly larger diameter than the greatest diameter of the internal bore of the sleeve 149. The edges 156 have outer curved surfaces 157 merging with the outer inclined surface of the lateral wall 154, and also inner curved surfaces 158 which lead to the opening 155 and to the enlarged free inner edge 159.

The adapter 153 may be removably or otherwise connected with the casing section of the nozzle unit 112 as by an annular groove 161 of an inner ring 160 of the adapter receiving an annular bead 162 outstanding from the outer end portion of the casing section of nozzle unit 112. The inner ring 160 is expanded and slipped over the bead 162 with its annular groove 161 registered with such bead 162. The inherent resiliency of the ring 160 will constrict such ring about the bead 162 in an interlocking fit. By prying out and expanding the ring 160 the adapter may be removed from the nozzle unit and another adapter of a diiferent size placed thereon, or the adapter if worn may be replaced.

The annular exhaust passage 150 communicates-at its inner end with a lateral or diagonal branch tube 163 of the nozzle unit 112 which extends partially about the air pressure chamber 117, with which this branch tube communicates through an eductor nozzle 164. This nozzle 164 is threadedly removably mounted in a nipple 165 of the casing section of the nozzle unit 112. This nipple 165 extends outwardly from the air pressure chamber 117. Any other suitable nozzle may be substituted for the nozzle 164 for use with a particular type of work in order to produce the desired aspirating or suction effect, it being understood that the delivery end of this eductor nozzle 164 is directed into the branch tube 163 in the direction of the return trunk 113 with which this branch tube 163 connects. It is evident that the eductor nozzle 164 corresponds, in effect, to the eductor nozzle 19 of the embodiment of Figs. 1-11.

A section 166 of the return trunk 113, which may be of metal, aluminum preferred, has its outer end seated with a slip fit into a smooth bore 167 and against a shoulder 168 of the branch pipe 163 in such manner that the nozzle unit 112 is rotatable upon the return trunk 113, thus forming, in eflect, a pivotal connection. A coil or other spring 169 coupled between the trunk section 166 and the nozzle unit 112 serves to maintain the trunk section 166 in the socket 167 while permitting of a relative rotation between these parts. The spring 169 will also tend to orient the nozzle unit 112 to a preselected angular position with respect to the return trunk. One end of the coil spring 169 for instance may be anchored to a headed pin 170 projecting radially from the pipe section 166, while the other end of the spring 169 carries a detachable metallic or other tab 171 having a keyhole slot therein adapted to slide over the head of a stud 173 on the nozzle unit 112. The coil spring 169 will automatically draw the tab to a position where the stud occupies the constricted end of the keyhole slot 172 so that in the position illustrated in Figure 15 the tab 171 is interlocked with the stud 173. By stretching the spring 169 and sliding the tab 171 downwardly, the wider end of the keyhole slot 172 may be brought opposite the head of the stud 173 whereupon the tab and spring may be detached from the stud 173 after which the nozzle unit 112 may be lifted off the trunk section 166 for adjustment or other purposes.

As better shown in Figure 12, the trunk section 166 affords suitable support for a clamp 174 usable to engage an intermediate portion of the abrasive feed line 111 to prevent fouling by this line 111 of the person of the operator, or other parts about to be encountered in the 10 course of the operation of the device. The remainder" of the return trunk 113 is preferably flexible to enable the various units at opposite ends thereof to be shifted to a variety of relative positions suitable to accommodate such units to various parts of the person of the operator.

As better shown in Figures 12 and 13, the dust sack 116 is formed with a month 175 adapted to fit over the outwardly flanged end 176 of an upstanding neck 177 on the cover 178 for the receptacle 110. A clamp 181 of any suitable form may be employed to bind the sack mouth 175 about the neck 177. A tubular diverting shield 179 projects downwardly from and into the cover 178 and is co-axial with the attaching neck 177. The lower end of the tubular shield 179 opens downwardly into the separating chamber 114 into which the trunk 113 delivers through a non-radial, preferably tangential connection 180.

A screen 182 in the receptacle 110 separates the separator 114 from the abrasive container 115, and may rest upon an outwardly extending flange 183 on the upper edge of the receptacle 110, which flange receives there beneath the lower shoulder 184 of an outwardly displaced bead 185 on the lower edge portion of the cover 178 which is of hard rubber or other suitable material possessing, at least at the head portion, sufiicient resiliency to enable the bead to be sprung outwardly to extend over the marginal edge of the screen 182 and over the flange 183. An upper shoulder 186 of the bead will resiliently clamp upon the top portion of the marginal edge of the screen 182 to firmly hold the same in place.

The receptacle 110 is preferably funnel shaped or narrower toward its base into which projects an abrasive discharge tube 187 with which the feed line 111 connects. Preferably the outer end of the tube 187 is made with a smooth Walled socket 188 having an internal stop shoulder 189 against which the inner end of the feed line 111 will abut. This feed line 111 at this point at least may be of hard rubber possessing some flexibility which will enable the same to be fitted into the socket 188 and to have sufficient rigidity to maintain the line 111 in the socket except when the same is forcibly removed therefrom.

In Figure 12, a bracket 190 on the trunk connection 180 is shown as receiving a supporting strap or harness looped about the left shoulder of the operator while the left hand engages a finger piece 192 on the receptacle 110 which is displaced angularly from the trunk connection 189 in a position where the hand may readily engage such finger piece 192 for the purpose of steadying the unit comprising the receptacle 110 with the dust collecting sack 116. By grasping the finger pieces 192 the unit may be prevented from undesirable movement which might otherwise occur incident to movements of the body of the operator.

In operation of this modification, the device may be mounted upon the person of the operator in the manner shown in Figure 12. The valve handle 125 and easing of the nozzle unit 112 are grasped in one hand so that the operator may squeeze the handle 125 to open the valve 119 while at the same time applying the adapter 153 of the nozzle unit 112 to the surface 194 to be treated. The air pressure line 112 will be connected to a suitable source of air under pressure which is introduced under control of the valve 119 to the globular or other air pressure chamber 117 in the nozzle unit 112. The air under high pressure will issue from this chamber in two directions. In one direction such air will pass through the annular frusto conical chamber between the valve end 136 and the inner convergent section 133 of the Venturi throat. The velocity of flow of air will be increased as it passes through this restricted throat. Such air will therefore draw by suction the abrasive material to and through the abrasive induction tube 135. In this way abrasive material from the receptacle 110 is pulled through the tube 187, feed line 111 and induction tube 135 into the nozzle throat where it is entrained with the air under high pressure. The comingled air and abrasive continues at high pressure through the expanding section 134 of the nozzle throat and through the inner casing or partition sleeve 14) out the wide end of which the abrasive is delivered with great force into and through the opening 155 of the adapter and against the surface 194.

In the second place, air under pressure from the air chamber 117 moves through the eductor nozzle 164 at high pressure into the branch 163 and into the pipe section 166 of the return trunk 113. Such air places the annular exhaust passage 15% under partial vacuum which acts to draw up the abrasive and air after the same have performed their work upon the surface 1%. In this way the abrasive, debris and air are delivered to the return trunk 113 and to the separating chamber 114 Due to the tangential delivery of the abrasive, debris and air through the connection 13!; to the separating chamber 114, such material will circle about the dependent tubular shield 179. Due to its greater specific gravity, the abrasive will be thrown out by centrifugal force to the outer portion of the separating chamber 114 and as it loses force of movement, such abrasive will drop by gravity onto and through the screen and back into the abrasive container 115 for subsequent reuse. The dust-laden air which is separated from the abrasive in the separating chamber 114 will escape through the tube 179 and neck 177 into the sack 116 carrying the dust and other lighter foreign particles which wil be entrapped in the sack 116 while the air will pass through the pores of the sack and escape into the surrounding atmosphere.

It will be noted from Figure 15 that the outer end of the division or partition sleeve 14-9 projects outwardly beyond the adjacent ends of the casing of the nozzle unit 112 and liner 151 and that the external surface of the projecting end of such sleeve 149 is preferably straight or cylindrical so as to bring the abrasive and air on its outward movement close to the opening 155 of the adapter 153 and at the same time to provide a surrounding division or partition which will enable-the abrasive and air after impinging against the surface 194 to more easily come under the influence of the suction in the annular exhaust passage 15%. Thus the spent abrasive and air in the adapter can more readily find its way into the mouth of the exhaust passage 1513-.

It will be understood from Figure 15 that there will be a pressure drop from the outside atmosphere across the adapter wall 154 and into the inner space of the adapter which may be constant or variable dependent upon the manipulation of the valve 119 by the operator. This pressure drop causes external atmospheric pressure to exert a force against the inclined er tapered wall 154 tending to push the wall, which is resilient, inwardly and slightly lift the edges 156 from the surface 194 permitting atmospheric air to enter around the circumference of the edges 156 and to enter the inner confined space of the adapter, which air will come under the influence of the suction produced by the nozzle 164 and be drawn into the exhaust passage 156 and ultimately into the return trunk 113. Such inflow of atmospheric air around the edges 1556 creates a countercurrent to any escaping abrasive or air from the interior of the adapter out into the atmosphere. Therefore due to the fact that the side wall 154 is solid and non-porous, yet yieldable and resilient, no abrasive may escape through the opening 155. Due to the curvature 157, 158 the edges 156 have substantially a line contact only with the surface 194, and where the adapter is annular, as shown, such line is a circle. It will of course be understood that only a limited flow of atmospheric air into the interior of the adapter chamber occurs relatively to the large mass of air passing therethrough having its origin from the chamber 117. The eductor nozzle 164 will create a high flow in the return trunk 113.

The flexible and resilient wall 154 of the adapter enables the same to accommodate it to irregular and cramped surfaces, to sharp corners and the like. When moving over an irregular surface, the external curvature 157 will first encounter the irregularity and permit the edges 156 at that point to lift slightly from the surface 194 riding over the irregularity but maintaining close contact with the surface of the irregularity and with the surface 194 at both sides of such irregularity.

In Figure 15 in dotted lines the enlarged free inner edge 159 is shown as having been moved up into the space adjacent the mouth of the exhaust passage 150, the wall 154- due to its inclination and form as shown requiring that the edge 159 move clear of the mouth of the exhaust passage 150 so as not to block or obstruct the same.

By backing off the lock nut 138 and rotating the threaded plug 137, the abrasive induction tube may be axially adjustable in or out so that its conical valve end 136 approaches more closely to or recedes further from the inner convergent section 133 of the Venturi throat. By thus screwing the tube plug 137 in or out the width of the annular air passage about the valve end 136 may be adjusted to control the rate of flow of the air and hence the volume of abrasive entrained with the air. The adjustment controls the amount of abrasive per unit volume of air. in other words such arrangement adjusts the ratio of the abrasive to the air.

Instead of using a hard abrasive material, a soft material may be employed for polishing, such soft material would still be an abrasive. Parts so section lined may be made of hard rubber and other parts of aluminum as both these parts resist attrition to a high degree.

The feed line 111 is held in the socket 139 by the action of suction. It will be understood that this feed line, while flexible, possesses a certain stiffness which together with its resiliency will tend to hold the feed line in the socket 139.

It will be appreciated that the invention provides a portable device all parts of which may be conveniently carried by the operator so as to move from place to place with him and to progress with him along the line of the surface to be treated. All large fixed and immovable parts are avoided and the relative arrangement of the units is such that while they are supported by the person of the operator the operating head is entirely free to be moved and manipulated to successive areas upon the surface to be treated and the units are so relatively arranged and provision is so made for the support of the elements about the body of the operator that the hands and arms of the operator are not impeded in their movements by any of the units or the lines connecting the same and the hands of the operator are entirely free to carry out the operations of polishing, cleaning, stripping, blasting, etc., with a minimum of effort and with a great economy of time.

Although there have been disclosed herein the best forms of the invention known to the inventors at this time, the right is reserved to all such modifications and changes as may come within the scope of the following claims.

What is claimed is:

1. A portable abrasive blasting machine comprising a nozzle unit including a blast nozzle, means for supplying compressed air to said nozzle, an abrasive container having a normal vertical position, means for supplying abrasive to said nozzle from said container, an air-abrasive separator connected to the output of said nozzle unit, and pivotal conduit connection means between said container and said separator, whereby said container may be maintained in vertical position irrespective of the position of said nozzle.

2. In a portable abrasive blasting machine, a blast nozzle unit manually supportable by an operator for wall, floor or ceiling blasting, means for supplying air under pressure to said nozzle unit, an abrasive container to be 13 carried by said operator in a normal vertical position, means for transporting abrasive from said container to said nozzle unit, and pivotal connection means between said nozzle unit and container, whereby thecontainer may be maintained in vertical position irrespective of the position of said nozzle unit.

3. A nozzle unit for blast machines comprising a valve block having a valve chamber therein, an eductor nozzle connected to said chamber, an injector nozzle connected to said chamber, a valve in said chamber having separate ports for said eductor and injector nozzles, means for supplying abrasive at said injector nozzle, a blast nozzle in line with said injector nozzle, a workpiece contactor, a chamber enclosing said blast nozzle extending to said contactor, a channel for blasted debris extending from said contactor to said eductor nozzle, and means for supplying compressed air to said valve chamber, whereby air is forced through said eductor, injector and blast nozzles on valve manipulation to open said valve ports.

4. A nozzle unit for portable blast machines comprising an elongated casing, a contactor at one end of the casing for application to a workpiece, means providing a suction chamber at the other end of said casing, a valve block adjacent the suction chamber end of said casing, a valve in said block for supplying only air under pressure to said suction chamber, a blast nozzle in said casing connected to said valve and directed toward the contactor end of said casing, means open to the discharge end of said nozzle for supplying abrasive particles, and a channel for conveying grit forming at said contactor to said suction chamber.

5. In an abrasive blast nozzle unit, a first tubular cas-.

ing, a ring-like work contactor secured to the end of said casing for application to a workpiece to be cleaned, a blast nozzle inside said casing, a second tubular casing inside said first casing and outside said nozzle, forming with said first casing a channel, and a ring-like screen at the mouth of said channel so as to bridge completely the channel mouth formed between said casings.

6. A nozzle unit for blast machines comprising a valve block provided with intersecting longitudinal and transverse channels positioned on the longitudinal and transverse aXes of said block respectively, an eductor nozzle threadedly engaging one end of said transverse channel, an injector nozzle threadedly engaging the opposite end of said transverse channel, means for supplying compressed air to said longitudinal channel and thereby to said transverse channel and said nozzles, a source of abrasive particles at said injector nozzle, a blast nozzle for applying the compressed air and abrasive particles at said injector nozzle to a workpiece, and a channel for conveying the grit from the surface of said workpiece to said eductor nozzle outlet.

7. .A portable abrasive blasting machine for removing debris from a coated surface that may be horizontal or inclined, comprising, a nozzle unit adapted to be located adjacent said coated surface, an abrasive container, an abrasive supply. conduit connecting said container with nozzle unit, swivelable connecting means between said container and nozzle unit whereby said container is maintainable in an upright position for various positions of said nozzle unit, an abrasive and debris return line connected to said nozzle unit, separator means connected with said return line and said container for separating abrasive particles from the debris, an air supply pipe adapted to be connected to a source of air supply at one end, air flow guiding means in said nozzle unit for dividing air from said air supply pipe into a blast stream and a suction stream, means directing said streams in distinct paths in said nozzle unit whereby said blast stream forces said abrasive particles on to said surface and said suction stream carries said particles from said surface to said abrasive container, said paths having portions providing for communication with said supply-conduit and said return line.

8. A portable abrasive blasting machine for removing debris from a coated surface that may be horizontal or inclined, comprising, a nozzle unit adapted to be located adjacent said coated surface, an abrasive container and separator means comprising a container portion for abrasive particles, a separator portion for separating abrasive particles from debris, and means for directing separated out abrasive particles to said container portion, an abrasive supply conduit connecting said container portion with said nozzle unit, means for maintaining said container portion upright, an abrasive and debris return line connecting said nozzle unit with said separator portion, said nozzle unit having means for receiving an air supply pipe connected to a source of air supply, air flow dividing means in said nozzle unit for splitting said air into a blast stream and a suction stream, said abrasive supply conduit having an outlet at said blast stream, whereby said blast stream forces said abrasive particles on to said surface and said suction stream carries said particles from said surface tosaid abrasive container portion, said dividing means comprising an injector means associating said blast stream with said abrasive supply conduit and an eductor means associating said suction stream with said return line, whereby said streams constitute substantially the sole source of power for recirculating abrasive particles in a path comprising said nozzle unit, said return line, said container and separator means and said supply conduit. A

9. A portable abrasive blasting machine for removing debris from a coated surface comprising, a nozzle unit, an abrasive container, abrasive supply and return conduits connecting said nozzle unit with said container, means for maintaining said container upright, means for supplying compressed air to said nozzle unit, a separator for separating abrasive particles from debris returned through said return conduit, means attaching said container to said separator, and a dust bag connected to an outlet of saidseparator, whereby the heavy abrasive particles are adapted to drop into said container while the lighter particles of debris are carried by means of air to said dust bag.

10. A portable abrasive blasting machine for removing debris from a coated surface comprising, a nozzle unit, an abrasive container, abrasive supply and return conduits respectively connecting said nozzle unit with said container, means for supplying compressed air to said nozzle unit, a separator in said return conduit connected between said nozzle unit and said container for separating abrasive from particles of debris returned through said return conduit, said separator comprising a receptacle having one side closed and the other side terminating in an opening, a dust bag secured to a wall forming said opening, and the air flow dividing means in said nozzle unit dividing said air into a blast stream and a suction stream, whereby said blast stream forces abrasive particles against said coated surface and said suction stream draws such abrasive and particles of debris through said return conduit to said separator.

11. A portable abrasive blasting machine for removing debris from a coating surface of various inclinations comprising, a nozzle unit, a unitary abrasive container and separator, an abrasive supply conduit connecting said container with said nozzle unit, an abrasive return conduit connecting said nozzle unit with said separator, abrasive pervious means between said separator and said container, and constantly open during operation of said machine, means for supplying compressed air to said nozzle unit, said nozzle unit comprising a valve connected to the last said means, a first passageway and a second passageway communicating with said valve, suction nozzle means centrally disposed in said first passageway, said nozzle unit having therein a blast nozzle, said supply conduit having an end at said blast nozzle, said blast nozzle being associated with said second passageway for directing abrasive particles against said coatedv surface,

a return channel formed in said nozzle unit, said channel being connected to said return conduit and said first passageway for carrying abrasive particles and debris from said surface to said separator, whereby a substantially open recirculatory path is provided in said blasting machine for continuously recirculating abrasive particles.

12. A portable abrasive blasting machine for removing debris from a coated surface of various inclinations comprising, a nozzle unit, an abrasive container, a separator connected to said abrasive container, an abrasive supply conduit connecting said container with said nozzle unit, an abrasive return conduit connecting said nozzle unit with said separator, means for supplying compressed air to said nozzle unit, said nozzle unit comprising an air control valve connected to the last said means, a first passageway and a second passageway connected to said valve, suction means disposed in said first passageway, said nozzle unit having therein a blast nozzle, said supply conduit having an end at said blast nozzle, said nozzle unit comprising a pair of spaced nested casings providing an inner space in which said blast nozzle is disposed, and an outer space providing an abrasive return channel, means connecting said abrasive return channel with said first passageway and said return conduit whereby said abrasive and particles of debris are returned through said channel and said return conduit to said separator.

13. The combination according to claim 12 wherein said valve supplies air simultaneously to each of said air passageways, and comprises means for changing the relative amounts of air from said valve to said passageways.

14. A portable abrasive blasting machine for removing debris from a coated surface comprising, a nozzle unit, an abrasive container, a separator connected to said container, abrasive supply and return conduits connecting said container with said nozzle unit, means for supplying compressed air to said nozzle unit, said nozzle unit comprising a first casing, an air control valve in said first casing connected at its inlet end to said compressed air supply and at its outlet end to a port in said casing, a chamber defined by the interior walls of said first casing in communication with said port, an eductor nozzle secured to said first casing and open to said chamber for directing air into said return conduit, a venturi throat open to said chamber, a blast nozzle in said first casing extending through said chamber and having its tip positioned in said throat, means connecting said abrasive supply conduit to said blast nozzle so that air flowing from said chamber through said throat draws abrasive particles through said blast nozzle, a second casing mounted within said first casing adjacent said throat and designed to direct said abrasive particles to said coated surface, means separating said first casing from said second casing thereby forming a return channel therebetween, and an adapter attached to the outer end of said first casing for surrounding the open ends of said first and second casings and adapted to contact said coated surface, whereby the abrasive particles drawn through said throat by the air from said chamber impinges against said coated surface enclosed by said adapter at a high velocity, the spent abrasive and particles of debris being returned to said return conduit by the suction created in said channel by said educator nozzle.

15. A nozzle unit for use with an abrasive blasting machine comprising, a first hollow casing having an inner and outer end, a second hollow casing mounted at its inner end within said first casing thereby forming a channel therebetween, a work-contacting adapter secured to the outer end of said first casing for contacting a coated surface, first suction nozzle means mounted on supporting means in said nozzle unit for creating a suction in said channel, second suction means comprising a nozzle mounted on said supporting means for drawing abrasive particles into said nozzle unit, and impinging them against said surface at high velocity whereby the spent abrasive and particles of debris are drawn into said channel by the action of said first suction means and ejected from said nozzle unit.

16. The combination according to claim 15 wherein said adapter comprises a rubber tubular member having a resilient part at its open work-contacting end, said resilient part comprising a converging open end portion terminating radially outward from the inner one of said casings, whereby said converging end portion can move in a direction toward said channel without blocking the channel.

17. The combination according to claim 15 wherein said adapter comprises a work-contacting end comprising a spring wire coil peripherally along the end of the adapter.

18. The combination according to claim 15 wherein said adapter comprises a round resilient member extending beyond the outer ends of said casings.

19. A nozzle unit for use with an abrasive blasting machine comprising, a valve block, a valve in said valve block adapted for connection to a compressed air supply, an eductor nozzle mounted on said valve block, an air chamber in said block, a port in a side wall of said chamber adapted for connection to an abrasive supply, an injector attached to said valve block having its tip positioned in said chamber, a blast nozzle secured to said block and axially aligned with said injector, a first hollow casing attached to said valve block adjacent said blast nozzle thereby forming a blast chamber, a second casing enclosing said valve block and said first casing, means positioning said second casing with respect to said first casing for providing an abrasive and debris return channel between said casings, means secured to the outer extremities of said casings for confining the abrasive particles therein, and means for providing communication between said channel and said eductor nozzle, whereby abrasive particles are adapted to be drawn into said air chamber by said injector and directed through said blast nozzle at a high velocity against said surface, the confined abrasive particles and particles of debris being discharged from the nozzle unit through said channel by the suction action of said eductor nozzle on said channel.

20. The combination according to claim 19 wherein said valve has a first port and a second port, a first position for said valve connecting said eductor nozzle with said first port and a second position for said valve simultaneously connecting said first port with said eductor nozzle and said second port with said injector.

21. A nozzle unit for use with a portable abrasive blasting machine comprising, a first casing having an open outer end, an air inlet port in a side wall of said casing terminating in an air chamber, first and second air outlets from said chamber, a hollow nozzle block having a venturi formed therein detachably fixed in said first outlet, a blast nozzle extending through said chamber and having the tip thereof terminating in the throat of said venturi so that air flowing from said chamber through said throat is adapted to draw abrasive particles through said nozzle, means adjustably mounting said nozzle on said first casing, a second hollow casing secured to said nozzle block and having its open outer end terminating adjacent a surface to be cleaned, means on said first casing for spacing said first casing from said second casing thereby providing a channel therebetween, an adapter secured to the open outer end of said first casing for contacting said surface, means integral with said first casing comprising an abrasive return outlet connected with said channel, an eductor nozzle secured in said second outlet from said air chamber and having the tip thereof positioned in said return outlet whereby abrasive particles impinging on said surface are adapted to be drawn through said channel by the aspirating effect caused by said eductor nozzle in said return outlet.

22. A nozzle unit for use with an abrasive blasting machine comprising a first hollow casing, a fiuid chamber formed in said casing, first and second fluid outlets from 17 said chamber, means including a venturimeans having a reduced pressure region connected with said chamber, an abrasive carrying tube in said first casing having its open end terminating in said reduced pressure region so that fluid flowing through said region draws abrasive particles from said abrasive carrying tube, a second hollow casing secured within said first casing and having its outer open end terminating adjacent the outer open end of said first casing, means aligning said second casing with said venturi means for directing abrasive particles to a coated surface, a return channel between said first and second casings terminating in an outlet tube, and an eductor nozzle mounted in said outlettube and in communication with said fluid chamber for creating an aspiratin g effect in said channel.

23. A portable and hand-holdable nozzle unit of a type described comprising a block means, an injector nozzle and an eductor nozzle mounted on said block means, said block means having an air pressure chamber communicating with said nozzles and adapted to be connected to a source of fluid pressure, an abrasive inlet located at a low pressure region adjacent said injector nozzle, whereby a mixture of abrasive and fluid can be obtained, a first tubular casing member to guide the mixture toward a work surface to be treated at an open end of said memher, a second tubular casing member surrounding said first tubular casing means to form a channel therebetween, said second tubular member having an open end adjacent the open end of the first tubular member, and passageway means in said nozzle unit connecting said channel to a relatively low pressure region adjacent said eductor nozzle.

24. A nozzle unit as defined in claim 23 but further characterized by a work adapter extending beyond said open ends of said tubular casing members, said work adapter being resilient and comprising a converging end portion.

25. A portable abrasive blasting machine to be carried and operated by a single operator for treating a work surface disposed horizontally or inclined, comprising a manually-manipulatable nozzle unit having a work-surface contactor with an open end, said nozzle unit having inlet means adapted to be connected to source of fluid under pressure, an abrasive inlet and a particle outlet, an abrasive container, an abrasive and debris separator having an outlet for separated-out abrasive particles, said nozzle unit further having means providing a first passageway from said abrasive inlet to said work-contactor end and a second passageway frorn said work-contactor end to said particle outlet, conduit means connecting said abrasive inlet, abrasive container, separator, and particle outlet to provide a continuously open endless recirculatory path for abrasive particles to pass from said container, through said first passageway into contact with said work surface, through said second passageway, into said separator and back to said container, and nozzle means disposed within said recirculatory path, connected to said inlet means, and providing substantially the sole source of power for forcibly recirculating abrasive particles in said recirculatory path.

26. A portable abrasive blasting machine as defined in claim 25 but further characterized by said separator and container comprising a unitary casing having a screen means therein dividing said casing into an upper portion comprising said separator and a lower portion comprising said container.

27. A portable abrasive blasting machine to be carried and operated by a single operator for treating a work surface disposed horizontally or inclined, comprising a manually operable nozzle unit, said nozzle unit comprising a workpiece contactor, abrasive container means, abrasive supply and return conduits connecting said nozzle unit with said container means, passage means in said nozzle unit adapted to receive compressed air, combined nozzle and passageway means in said nozzle unit leading to said work surface and connected to said passage means for receiving compressed air from said passage means, said combined nozzle and passageway means having a portion having a first reduced pressure region providing a suction in said abrasive supply conduit from forcing abrasive from said container means through said supply conduit and toward said workpiece contactor, said combined nozzle and passageway means having another portion having a reduced pressure region and associated with said return conduit for drawing particles from inside said workpiece contactor near said surface and forcing abrasive particles through said return conduit to said container means.

28. A portable abrasive blasting machine for treating a-work surface disposed horizontally or inclined, comprising a nozzle unit; an abrasive container; a separator for sepaarting abrasive particles from debris particles, said separator having an outlet for separated-out abrasive particles; connection means connecting said separator outlet to said container; a relatively short abrasive supply conduit connecting said container with said nozzle unit; a relatively short return conduit connecting said nozzle unit with said separator; said nozzle unit comprising inlet means adapted to be connected to a source of pressurized air, a blast passageway, a suction passageway, passage means connecting said inlet means to said passageways, said passage means comprising an air pressure chamber and air flow dividing means for respectively directing air from said inlet means into said blast passageway in a direction toward said surface and into said suction passageway in a direction away from said surface, said passage means containing nozzle means for developing, within the nozzle unit and through action, of pressurized air from said inlet means, the air flow required to deliver abrasive particles forcibly to said surface and the suction required for evacuating expended abrasive particles, debris and spent air from the nozzle unit.

29. A portable and hand-holdable nozzle unit of a type described having a work contactor with an open end to be placed against a work surface to be treated, said nozzle unit comprising a block means having an air pressure chamber for connection to a source of gas under pressure, an eductor nozzle communicating with said chamber, said nozzle unit having a passageway about the discharge end of said eductor nozzle, a pair of nested spaced tubular casings providing a channel therebetween, said work contactor being attached to the outer casing of said tubular casings and extending beyond the inner casing, said passageway communicating with said channel, said eductor nozzle having its discharge end directed in a gas-flow direction which is away from said open end of said work contactor, and nozzle means communicating with said chamber to provide a flow of abrasive particles in the space within said inner casing in a direction toward said open end of said work contactor.

30. A portable nozzle unit for a blasting machine, said unit having a pair of spaced nested casings providing an inner space in which abrasive is directed toward a work surface, and an outer channel in which spent abrasive is drawn in a direction away from said surface, and a work contactor on the outer end of the outer of said casings, said work contactor having a tubular converging end portion of rubber.

31. A nozzle unit as defined in claim 30 but further characterized by said tubular end portion terminating radially outward of the inner one of said casings, and being movable in a direction toward said channel without blocking said channel.

32. A portable abrasive blasting machine to be carried and operated by a single operator for treating work surfaces disposed horizontally or inclined, comprising a manually-manipulated nozzle unit having a work-surface contactor with an open end, said nozzle unit having an abrasive inlet and a particle outlet, a separator and container means having an inlet opening for particles comprising abrasive and debris and having an outlet opening for separated-out abrasive particles, said nozzle unit further having means providing a first passageway from said abrasive inlet to said work-contactor end and a second passageway from said workcontactor end to said particle outlet, conduit means connecting said outlet opening, abrasive inlet, particle outlet and inlet opening to provide a continuously open endless recirculatory path for abrasive particles to pass from said separator and container means, through said first passageway into contact with said work-surface, through said second passageway and back to said separator and container means, and nozzle means disposed within said recirculatory path, adapted to be connected to a source of fluid under pressure, and providing substantially the sole source of power for forcibly recirculating abrasive particles in said recirculatory path.

References Cited in the file of this patent UNITED STATES PATENTS 681,867 Bardwell Sept. 3, 1901 847,269 Wise Mar. 12, 1907 2,230,690 Lanza Feb. 4, 1941 2,455,514 Mead Dec. 7, 1948 2,494,773 Mead et al. Jan. 17, 1950 FOREIGN PATENTS 15,730 Great Britain 1899 487,532 Great Britain June 22, 1938

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