US3896998A

US3896998A - Apparatus for spraying particulate material

Info

Publication number: US3896998A
Application number: US438617A
Authority: US
Inventors: Charles F Vertue
Original assignee: Volstatic of Canada Ltd
Current assignee: C-I-L Inc A CORP OF CANADA; HANSON (1984) Inc; Volstatic of Canada Ltd; PPG Architectural Coatings Canada Inc
Priority date: 1972-09-25
Filing date: 1974-02-01
Publication date: 1975-07-29
Anticipated expiration: 1992-07-29

Abstract

Particulate material spraying apparatus comprises an extractor device having an inlet passage extending from the mouth of an inlet nozzle at one end of the inlet passage and a compressed gas passage extending past the other end of the passage to entrain particulate material through the inlet nozzle and inlet passage, to a flexible pipe leading to a spray gun. To prevent choking by accumulation of the material in or on the extractor device, the inlet nozzle has a tapered outer surface converging with the inlet passage at the mouth, and a vibrator is provided for vibrating the nozzle. The extractor device may be attached to the wall of a container for the particulate material, or may be separate from the container to facilitate transference of the extractor device to a different container.

Description

O United States Patent 1 1 1111 3,896,998 Vertue July 29, 1975 [541 APPARATUS FOR SPRAYING 2,545,829 3 1951 Spreng 222 193 I M TE AL 3,134,513 5/1964 Ashman 222/193 PART CULATE A R 3,637,135 1/1972 Luderer et a1. 222/193 X Inventor: Charles t C le, 3,740,612 6/1973 Gauthier et a1. 117/934 x Canada 3,795,348 3/1974 Vertue 222/193 [73] Assignee: Volstatic of Canada Limited, FOREIGN PATENTS OR APPLICATIONS Canada 651,407 4/1951 United Kingdom 222/193 [22] Filed: Feb. 1, 1974 Primary Examiner-Robert S. Ward, Jr. [211 PP 438,617 Attorney, Agent, or FirmStaas & Halsey Related U.S. Application Data [63] Continuation-impart of Ser. No. 314,737, Dec. 13, [57] ABSTRACT 1972, abandoned. Particulate material spraying apparatus comprises an extractor device having an inlet passage extending [30] Foreign Application Priority Data from the mouth of an inlet nozzle at one end of the Sept. 25, 1972 Canada 152412 inlet P g and a compressed gas Passage extending Dec. 18, 1973 Canada 188393 P the other 9nd of the Passage to ehtraih Particulate material through the inlet nozzle and inlet passage, to 52 U.S. c1. 239/106; 239/318; 222/193; a flexible p p leading to a p y To Prevent 2 9 5; 3 5 239 54 choking by accumulation of the material in or on the [51] 305 5 02; 5053 5 02; 3 5 53/42 extractor device, the inlet nozzle has a tapered outer [58] Field of Search 239/3, 15, 8, 654, 106, surface converging with the inlet Passage at the 239/310, 318, 340, 372; 1l7/93.4 R, 93.4 A, 93.4 NC, 17; 118/302, 7; 317/3; 222/193; 302/58 [56] References Cited UNITED STATES PATENTS 2,187,376 1/1940 Guibert 222/193 mouth, and a vibrator is provided for vibrating the nozzle. The extractor device maybe attached to the wall of a container for the particulate material, or may be separate from the container to facilitate transference of the extractor device to a different container.

15 Claims, 10 Drawing Figures PATENTEDJULZQIHIS 3,896,998

SHEET 2 FIG. 2.

PATENTEDJULZSISYS 3, 896,998

SHEET PATENTED Z IHYS a. 896,998

SHEET 4 PATENTED JUL 2 9 I975 SHEET FIG. 7.

APPARATUS FOR SPRAYING PARTICULATE MATERIAL lier application Ser. No. 314,737, filed Dec. 13, 1972,

now abandoned.

The present invention relates to apparatus for spraying particulate materials.

The spraying of materials in powdered form, such as synthetic resins and pigments, and powdered metals, onto substrate to form coatings on the substrates has the advantage that at least part of the material sprayed, but which does not form part of the coating, may be recycled for reuse, thus providing considerable economy and reduction of pollution in comparison to the use of liquid spraying.

For delivering particulate material to a spray gun, it has previously been proposed to use an extractor device for extracting particulate material from a bed of the material, the extractor device having an inlet passage communicating at one end thereof with the bed through an inlet to the extractor device, and means for discharging compressed gas, e.g. air, past the other end of the inlet passage, so that particulate material is thereby entrained from the inlet passage through a flexible hose to a spray gun.

It has been found that in practice the particulate material has a tendency to deposit on and around the inlet to the extractor device and thereby build up into an accumulation of the particulate material which eventually interferes with the flow through the inlet passage, causing this flow to be choked and thereby causing an uneven discharge of the particulate material from the spray gun. This effect may also be caused or increased by partial or complete blockage of the inlet passage by flakes or lumps formed by mutual adherence of recycled particles of the particulate material.

In my co-pending patent application Ser. No. 278,320, filed Aug. 7, 1972 now U.S. Pat. No. 3,795,348, issued Mar. 5, 1974, In have disclosed a device for conveying particulate material by entraining the latter in a flow of gas, the device being provided with an inlet nozzle which, to counteract accumulation of the particulate material, has an outer surface which tapers towards the mouth and converges with a passage through the nozzle, so that no shoulder is formed around the nozzle mouth which would facilitate such accumulation.

It is, accordingly, an object of the present invention to provide particulate material spraying apparatus having novel and improved means for counteracting blockage of the flow of the particulate material through the apparatus.

According to the present invention, a vibrator is provided for vibrating the nozzle and further counteracts the deposition of particulate material on the unit and facilitates breaking-up of any lumps or flakes of the particulate material.

Further objects, features and advantages of the present invention will be more readily understood from the following description thereof given by way of example with reference to the accompanying drawings, wherein:

FIG. 1 shows a diagrammatic front view in elevation of a particulate material spraying apparatus according to the present invention;

FIG. 2 shows a view taken in vertical section through a powder funnel and container forming part of the apparatus of FIG. 1;

FIG. 3 is a broken-away view illustrating part of the apparatus of FIG. 1;

FIG. 4 shows a broken-away view taken in section along the line IV--IV of FIG. 3;

FIG. 5 shows a view taken in section through an outlet unit forming part of the apparatus of FIG. 1;

FIG. 6 shows a diagrammatic side view in transverse cross-section of powder conveying apparatus embodying the invention;

FIG. 7 shows a plan view of a housing and a powder extraction device forming parts of the apparatus of FIG. 6;

FIG. 8 shows a view taken in section along the line VIII-VIII of FIG. 7;

FIG. 9 shows a rear view of the housing and powder extraction device, viewed in the direction of arrow A of FIG. 7; and

FIG. 10 shows a view taken in cross-section through a powder inlet nozzle and associated parts of the powder extraction device of FIGS. 6 to 9.

With reference firstly to FIG. 1, the spraying apparatus illustrated therein has a powder storage unit indicated generally by reference numeral 10. The powder storage unit 10 has an upper frusto-conical portion 11 disposed on a lower, cylindrical container portion 12.

As can be seen from FIG. 2, the lower, cylindrical container portion 12 also supports a cylindrical powder retaining wall 14, which extends upwardly from the lower cylindrical container portion 12 within the frusto-conical portion 11. The cylindrical powder retaining wall 14 is provided with a plurality of support struts 15, by which a conical cover 16 is supported at a spacing above the top of the cylindrical powder retaining wall 14, the cover 16 projecting laterally beyond the cylindrical powder retaining wall 14.

The lower end of the cylindrical powder retaining wall 14 is provided with a plurality of circumferentially spaced circular openings 17. The frusto-conical portion 11 contains a body of powder 18, which can flow through the openings 17 and drop into the underlying lower cylindrical container portion 12.

The lowermost end of the lower cylindrical container portion 12 is closed by a circular bottom 20. A membrane 21 extending transversely across the whole area of the interior of the lower cylindrical container portion 12, and supported from the inner surface of the lower cylindrical container portion 12 by means of an annular support bracket 22, divides the interior of the lower cylindrical container portion 12 into an upper chamber 24 and a lower chamber 25.

The lower chamber 25 is provided with an inlet pipe 26 which is connected by a branch 27 of the pipeline 28 (see FIG. 1) to a compressed air pump P.

The pump P is further connected by the pipeline 28, through

branches

29 and 30, to a pair of powder extractor devices 31, which in turn are connected by flexible pipelines 32 to respective spray guns 33. The spray guns 33 may for example by mounted on a reciprocating mechanism (not shown) for spraying articles in a spray booth (not shown), and may be a conventional type of spray gun used for electrostatic coating.

Referring now to FIGS. 3 and 4, it will be seen that each of the two extractor devices 31 are connected to a plate 35, on which there is supported a vibrator 36.

The plate 35 has an arcuately shaped portion 37, the curvature of which corresponds to that of the lower cylindrical container portion 12. A sheet 39 of rubber is sandwiched between the plate portion 37 and a similarily arcuately curved metal plate 40. The rubber sheet 39 forms a closure for an opening 42 formed in the wall of the lower cylindrical container portion 12, and the plate 40 fits into, and is spaced from the edge of, the opening 42. The plate 35, with the vibrator 36 and the extractor devices 31, are thus resiliently supported by the rubber sheet 39 on the lower cylindrical container portion 12.

Each of the extractor devices 31 has an inlet nozzle 60 projecting into the interior of the lower cylindrical container portion 12 within the chamber 24.

FIG. shows in greater detail the construction of one of the extractor devices 31. As can be seen from FIG. 5, the unit illustrated therein has a generally T-shaped body in the form of a Tee-piece indicated generally by reference numeral 45, which is threaded at the ends of each of its arms. Internally threaded

retainers

46, 47 and 48 are in threaded engagement with these threaded arm ends of the Tee-piece 45. The retainer 46 connects a flanged end of an outlet pipe 50 to the Tee-piece 45, and the other end of the outlet pipe 50 is formed on its outer periphery with annular ribs 52 for engagement with the respective flexible pipeline 32.

The retainer 47 engages a flange 54 on a nozzle 55 extending into the Tee-piece 45 and thereby retains the nozzle member 55 in position as shown. The nozzle 55 has a threaded end 56 projecting away from the Teepiece 45 beyond the retainer 47 for engagement with the

respective branch pipeline

29 or 30, this threaded end 56 being formed internally with a flared mouth 57 communication with a bore 58, which in turn extends to and communicates with a discharge orifice 59 at the opposite end of the nozzle 55.

The retainer 48 connects an inlet nozzle 60 to the third arm of the Tee-piece 45 and clamps the Tee-piece 45 to the

plates

35 and 40 and the rubber sheet 39, the inlet nozzle 60 being formed with an annular shoulder 61 for engagement with the retainer 48. An inlet passage or bore 62 extending longitudinally through the inlet nozzle 60 communicates with a bore 63 extending through one arm of the Tee-piece 45 to a frustoconically diverging gas discharge passage 64, which extends from the bore 63 to a cylindrical passage 65 extending through the interior of the pipe 50, the

passages

64 and 65 being held in alignment by the retainer 46. The upper end of the bore 63 and the frustoconically diverging gas discharge passage 64 form parts of a venturi, the nozzle discharge orifice 59 being directed towards the frusto-conically diverging gas discharge passage 64 and communicating with the upper end of the bore 63.

The inlet nozzle 60 has a frusto-conically shaped outer surface 70, which tapers to the inlet end of the bore 62 to form a thin, annular, substantially knifeedged rim or mouth around the inlet end of the bore 62,, where the outer surface 70 converges with the bore 62.

The operation of the above-described apparatus is as follows:

The powder 18, which for example may be a powder paint comprising a mixture of powdered synthetic resin material and pigment particles, is discharged through the open top of the frusto-conical portion 11 of the powder storage unit or container 10, and deflected laterally by the cover 16 so that it accumulates between the wall of the frusto-conical portion 11 and the cylindrical powder retaining wall 14. Some of the powder 18 falls through the openings 17 into the lower cylindrical container portion 12, and more particularly into the chamber 24.

A suitable gas under pressure, for example compressed air or an inert gas, is supplied by the pump P through the pipeline 28, the branch pipeline 27 and the inlet 26 into the chamber 25 and diffuses through the membrane 21 into the chamber 24, so that the powder in the chamber is fluidized.

The compressed air or inert gas is also supplied through the pipeline 28 and the

branch pipelines

29, 30 to each of the extractor devices 31, and more particularly to the nozzles 55. In each extractor device 31 the,

air or gas flows through the orifice 59 into the frustoconical passage portion 64 and thereby entrains a mixture of gas and the powder 18 from the chamber 24 through the nozzle 60 and the inlet passage formed by

bores

62 and 63 into the frusto-conically diverging passage portion 64, and thence through the cylindrical passage 65 of the pipe 50, and through the respective flexible pipeline 32, to one of the spray guns 33, where the mixture is discharged onto a substrate which is to be coated.

At the same time, the vibrator 36 is energized to oscillate the plate 35, which is resiliently supported by the rubber sheet 39, and thereby to vibrate the extractor devices 31 to prevent accumulation of powder at the extractor devices 31 and in particular at the mouths of the inlet nozzles 60. The accumulation of powder at the inlet end of each inlet nozzle 60 is also counteracted by the tapering of the outer surface thereof to the inlet end of the passage 62, so that no flat inlet end is presented by the nozzle 60 on which powder could be accumulated.

A further problem which may arise when spraying powder paint may be a requirement that the spraying apparatus should be readily and quickly changed over from powder of one colour to powder of a different col our. However, rapid changeover of the powder colour may be hindered by the fact that the powder tends to adhere to some extent to the apparatus employed, and the adhering powder may contaminate powder of a different colour sprayed by the apparatus after the changeover.

Rapid changeover from powder paint of one colour to that of another colour is facilitated by the apparatus illustrated in FIGS. 6 through 10.

The apparatus illustrated in FIG. 6 has a powder container indicated generally by reference numeral 110, which is open-topped and which has an upper, frustoconical portion 111 extending from a lower, cylindrical portion 112. A supply of paint powder 114 is held in the container on a horizontal partition 115.

The horizontal partition 115 is made of a porous material, for example porous polyvinyl chloride, and provides a porous support surface for the powder 1 14. The partition 115, together with part of the wall of the cylindrical container portion 112 and a bottom 116 closing the underside of the container 110, form a compressed gas chamber 118, which has a compressed gas inlet opening 119.

On the upper, porous surface of the partition 115 there are supported a housing indicated generally by reference numeral 120 and a powder extractor device indicated generally by reference numeral 121. A flexible pipe 122 extends from the housing 120, and

flexible pipes

123 and 124 extend from the powder extractor device 121. The

flexible pipes

122, 123 and 124 extend upwardly to the open top of the container 111 and are connected beyond the container to other apparatus which will be referred to hereinafter.

As shown in FIGS. 7 to 9, the housing 120 is formed by an open-topped metal box 126 having at its top an inturned flange 127, and a porous wall portion in the form of a porous plate 128, which is secured to the top of the box 126 in an airtight manner by means of a plurality of rivets 129 extending through the flange 127.

A vibrator 130, which is operated by compressed air, is resiliently supported within the housing 120 in a manner described in more detail hereinafter, and has an inlet 131 and an outlet 132 (FIG. 7) for the flow of the compressed air to and from the vibrator 130. The vibrator outlet 132 discharges the compressed air directly within the interior of the container 120 and this compressed air then passes through the porous plate 128.

The vibrator 130 is connected, at the vibrator inlet 131, to a connecting pipe 134, which extends to the exterior of the housing 120 for connection to the flexible pipe 122, which serves to supply the compressed air from a suitable soure, e.g. the pump P of FIG. 1, to the vibrator 130 for operating the latter.

The powder extraction device 121 is mounted on the connecting pipe 134 by means of a support bracket indicated generally by reference numeral 135, which is made of sheet metal and has a vertical portion 136, which is clamped at its lower end around the connecting pipe 134 by means of a sleeve 137 and a threaded collar 138 in threaded engagement with the connecting pipe 134.

The upper end of the bracket is bent to provide a horizontal portion 140 and two further vertical bracket portions 141 (see FIG. 7) extending upwardly from the horizontal portion 140 and parallel to one another.

Each of the vertical bracket portions 141 supports two blocks 143 of plastic material, which are secured thereto by means of nuts 144 and bolts 145 extending through the blocks 143. Each of the blocks 143 has a powder inlet nozzle 147, a compressed air inlet nozzle 48, and an outlet nozzle 149 for the flow of a mixture of compressed air and entrained powder. The compressed air inlet nozzle 148 is connected to the flexible pipe 124 (FIG. 6), which in turn is connected to a source of compressed air, e.g. the pump P of FIG. 1, and the outlet nozzle 149 is connected to the flexible pipe 123. When the present apparatus is employed as part of a spraying apparatus, the flexible pipe 123 is connected to a spray gun, e.g. one of the spray guns 33 of FIG. 1. However, it is to be understood that the apparatus illustrated in FIGS. 7 to 9 may be employed, for example, for transferring powder from one container to another or for transferring powder from a supply box to the container 110 or another container.

In addition, while only one of each of the

flexible pipes

123 and 124 have been illustrated in FIG. 1, for convenience of illustration, it is to be understood that each of the inlet nozzles 148 and each of the outlet nozzles 149 is connected to a respective flexible pipe. Of course, in a modification of the apparatus, a single flexible pipe for the supply of compressed air could be connected by a suitable manifold to each of the inlet nozzles 148. Similarly, each of the nozzles 149 could be connected by a suitable manifold arrangement to a common outlet pipe.

Referring now to FIG. 10, which shows one of the nozzles 147 and the associated block 143, inlet nozzle 148 and outlet nozzle 149, it can be seen that the block 143 is provided with a boring 150' communicating with the inlet nozzle 148 and with a further boring 151 in the block 143. One end of the boring 151 is closed by a grub screw 152, and the other end of the boring 151 communicates through an opening 153 in the wall of the outlet nozzle 149 with a boring 154 in a flow constriction nozzle 155 inserted into the outlet nozzle 149. The flow constriction nozzle 155 has an axial boring 156 communicating with, and having a smaller crosssection than, the boring 154, and serves to constrict the flow of the compressed air fed in through the inlet nozzle 148 and thereby to accelerate this compressed air.

The powder inlet nozzle 147, which forms a powder inlet through which the powder flows to the outlet nozzle 149, is made of plastic material and has at one end a threaded portion 158 which is in threaded engagement with the block 143. An axial inlet passage extending through the nozzle 147 is formed by a first boring 159 extending from the other end of the inlet nozzle 147 and a second boring 160, which has a larger cross section than the first boring 159 and is in axial alignment and communication with the first boring 159 and with a frusto-conically divergent mouth 161. The mouth 161 communicates through an opening 162 in the wall of the outlet nozzle 149 with the interior of the outlet nozzle 149 opposite the outlet end of the boring 156 of the flow constriction nozzle 155.

The powder inlet nozzle 147 has a frusto-conical outer surface 164 which converges with the wall of the bore 159 to form a circular knife-edge 165 at the outer, inlet end of the boring 159, where the outer surface converges with the bore 159 at the mouth of the inlet nozzle 147.

The block 143 is also provided with a boring 167 extending through the block 143 for receiving one of the bolts 145 which, together with its associated nut 144, serves to clamp the block 143, in a pair of such blocks, to one of the vertical bracket portions 41, as shown in FIG. 7.

It will be noted that the four powder inlet nozzles 147 extend parallel to one another and to the porous plate 128 and have their inlet ends spaced above the porous plate 128. I

As has been mentioned hereinabove, the vibrator 130 is resiliently mounted within the housing 120. For

this purpose, one wall of the box 126 is formed, as illustrated in FIG. 9, with a rectangular opening 170, which is closed by a sheet 171 of Neoprene (Trade Mark) clamped over the opening-171]! by a rectangular frame 172, which is firmly secured to the box 126 by means of a plurality of screws 173.

The collecting pipe 134 extends through an opening (not shown) in the resilient sheet 171 and is secured thereto by means of a nut 175 (FIG. 8), which clamps the resilient sheet 171 against the sleeve 137, suitable washers (not shown) being provided between the nut 175, the sleeve 137 and the resilient sheet 171.

The operation of the above-described apparatus is as follows:

With the powder 114 in the container 110, and the housing 120 resting on the partition 115 within the powder 114 as shown in FIG. 6, compressed air is supplied to the chamber 118 through the inlet 119, to the vibrator 130 through the flexible pipe 122, and to the powder extraction device 121 through the flexible pipes 124.

The compressed air in the chamber 118, which escapes upwardly through the-porous partition 115, and also the compressed air from the outlet of the vibrator 130, which escapes from the housing 120 through the porous plate 128, forms a fluidized bed of powder around the powder inlet nozzles 147, which are caused to vibrate by the motion of the vibrator 130, the fluidized bed facilitating flow of the powder through the nozzles 147.

The compressed air entering each of the blocks 143 through the respective compressed air inlets nozzles 148 passes in turn along the

borings

150 and 151, through the opening 153, and along the boring 154 to the constricted boring 156, from the outlet end of which the compressed air is discharged as an accelerated jet, which creates a partial vacuum at the mouth 161 of the powder inlet nozzle 147 for drawing powder through the latter frq the' fluidized bed. The vibration caused by the vibrator 130, and the use of the knifeedge 165 at the inlet end of the powder inlet nozzle 147, counteracts the build-up of powder at the inlet to the powder nozzle boring 159, which helps to avoid clogging of the latter. The powder, entrained in the accelerated stream of compressed air jetting from the flow constriction nozzle l55,is carried through the outlet nozzle 149 and along the flexible pipe 123.

When it is desired to change-over to a powder of a different colour, the housing 120 and the powder extraction device 121 are withdrawn as a unit from the container 110 merely by pulling the

flexible pipes

122, 123 and 124, and are then cleaned by means of a suitable suction device to remove any of the powder 114 adhering thereto. 'A burst of compressed air is passed through the powder extraction device 121 to remove any of the powder/114 which may be remaining in the flexible pipe 123 and any apparatus connected thereto. By supplying compressed air through the flexible pipe 122, powder adhering to-the plate 128 can be removed.

In addition, a suitable suction cleaner device is employed to remove powder from the exterior of the housing 120 and the powder extraction device 121, and these parts can then be placed in the powder of a different colour for conveying that powder.

While the apparatuses described above with reference to the accompanying drawings make use of a fluidized bed of powder, it is to'be understood that it is not essential to fluidize the powder bed, and that the extractor, devices will operate satisfactorily in nonfluidized powder beds.

.1 claim:

1. Particulate material spraying apparatus comprising:

a container for particulate material;

an extractor device for extracting particulate material from said container;

a particulate material discharge device for discharging the particulate material;

an outlet duct connecting said extractor device to said discharge device;

said extractor device having an inlet nozzle and means defining an inlet passage extending through said nozzle, said nozzle defining a mouth at one end of said inlet passage, said nozzle having an outer surface which tapers towards said mouth and converges with said inlet passage at said mouth;

a gas discharge passage extending past the other end of said inlet passage;

means for discharging compressed gas through said gas discharge passage past said other end into said outlet duct, whereby particulate material is entrained from said inlet passage and driven through said outlet duct to said discharge device; and

a vibrator for vibrating said nozzle to counteract accumulation of the particulate material on said nozzle.

2. Particulate material spraying apparatus as claimed in claim 1, and further comprising means defining an opening in one side of said container, said extractor device extending through said opening with said nozzle projecting into the interior of said container, and a resilient closure extending between said container and said extractor device and closing said opening.

3. Particulate material spraying apparatus as claimed in claim 1, wherein said vibrator and said powder extractor device are combined as a unit separate from said container to enable said unit to be readily transferred from said container to a different container.

4. Particulate material spraying apparatus as claimed in claim 3, and further comprising a housing forming part of said unit, said housing having an inlet for the entry of compressed gas into said housing and at least one porous wall portion for escape of the gas from said housing to the particulate material in said container.

5. Particulate material spraying apparatus as claimed in claim 4, wherein said vibrator has an inlet for flow of compressed gas into said vibrator to operate said vibrator and an outlet for discharging the gas from said vibrator, said vibrator outlet communicating with the interior of said housing for discharging the gas from said vibrator through the interior of said housing and through said porous wall portion.

6. Particulate material spraying apparatus as claimed in claim 5, wherein said vibrator is mounted with said housing.

7. Particulate material spraying apparatus as claimed in claim 4, wherein said vibrator is resiliently connected to said housing.

8. Particulate material spraying apparatus as claimed in claim 4, wherein said housing has an opening in one wall thereof, said opening is closed by resilient material secured to said wall, and said vibrator is supported by said resilient material.

9. Particulate material spraying apparatus as claimed in claim 3, wherein flexible pipes are connected to said housing inlet and said extractor device outlet for supply of the compressed air and discharge of the particulate material, said housing and said extraction device being removable from said container by means of said flexible pipes.

10. Particulate material spraying apparatus as claimed in claim 3, comprising a support by which said extraction device is held in a predetermined position in relation to said porous wall portion.

11. Particulate material spraying apparatus as claimed in claim 3, wherein said container has a porous surface for supporting said unit, a compressed gas chamber beneath said porous surface, and a compressed gas inlet opening into said chamber for supplying compressed gas through said chamber and said porous surface to fluidize the powder in said container.

12. Particulate material spraying apparatus as claimed in claim 4, wherein said container has a porous surface for supporting said housing, a compressed gas chamber beneath said porous surface, and a compressed gas inlet opening into said chamber for supplying compressed gas through said chamber and said porous surface to fluidize the powder in said container.

13. Particulate material spraying apparatus as claimed in claim 3, wherein said porous wall portion forms a top for said housing.

14. Particulate material conveying apparatus for extracting particulate material from a bed of such material, comprising an extractor device, said extractor device having an inlet nozzle, means defining an inlet passage extending through said inlet nozzle, said inlet nozzle defining a mouth at one end of said inlet passage, said nozzle having an outer surface which tapers towards said mouth and converges with said inlet passage at said mouth, and a gas discharge passage extending past the other end of said inlet passage, and a vibrator for vibrating said nozzle to counteract accumulation of the particulate material on said nozzle.

15. Particulate material conveying apparatus as claimed in claim 14, wherein said extractor device is adapted for insertion into a container and formed as a unit separate from the container.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patgnt No. 318961998 D t d July 29, 1975 Inventor(s) CHARLES VERTUE It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, line 41, "In" should be -I-. Column 2, 'line 61, "by" should be --be. Column 5, line 47, "48" should be .l48. Column 6, line 46, "41" should be -l4l.

Signed and Sealed this twenty-first Day of October 1975 [SEAL] Attest:

RUTH C. MASON C. MARSHALL DANN Arresting Officer Commissioner nfPaIents and Trademarks

Claims

1. Particulate material spraying apparatus comprising: a container for particulate material; an extractor device for extracting particulate material from said container; a particulate material discharge device for discharging the particulate material; an outlet duct connecting said extractor device to said discharge device; said extractor device having an inlet nozzle and means defining an inlet passage extending through said nozzle, said nozzle defining a mouth at one end of said inlet passage, said nozzle having an outer surface which tapers towards said mouth and converges with said inlet passage at said mouth; a gas discharge passage extending past the other end of said inlet passage; means for discharging compressed gas through said gas discharge passage past said other end into said outlet duct, whereby particulate material is entrained from said inlet passage and driven through said outlet duct to said discharge device; and a vibrator for vibrating said nozzle to counteract accumulation of the particulate material on said nozzle.