GB2145389A - Apparatus for feeding particulate materials - Google Patents

Abstract

A vibratory cylinder 13, vibrated by an electrically driven mechanism 46, receives powder from a reserve chamber 21 through a feed tube 22 ending just above the floor 14 of the cylinder 13. Powder is driven, by the vibration of the cylinder 13, up a helical channel 17 formed on the inner cylindrical wall of the cylinder 13 and leaves through a connection 18, 19 and a duct 8 to a nozzle 9. Operation of the mechanism 46 is controlled by the same switch 44 as a solenoid valve 10 in the duct 8. Compressed air pressurises the reserve chamber 21 and a feed chamber 12 enclosing the cylinder 13, supply and exhaust solenoid valves 35 and 39 being controlled jointly from a switching circuit 41. <IMAGE>

Description

SPECIFICATION Apparatus for feeding particulate materials This invention is concerned with the feeding of particulate materials, especially powder materials.

While not limited thereto, the equipment of the present invention is especially well adapted to the feed of abrasive particulate material in a pressurized gas stream. Because of the special adaptability of the apparatus to this type of use, the invention is illustrated in the drawings and described hereinafter in connection with an adaptation particularly suited to use for abrasive purposes.

Various forms of equipment for the above purpose have been known and the invention is concerned with a number of improvements, especially relating to the particular feed mechanism.

One of the principal objects of the present invention is the provision of apparatus for feeding particulate material and providing for establishment of a controllable but precise stream of the particulate material.

According to the present invention there is provided apparatus for feeding particulate material into a gaseous stream, comprising a gas flow duct having an inlet, a vibratory feed chamber adapted to feed a stream of particulate material into the inlet of the gas flow duct, the wall of the chamber being mounted for vibratory movement, and means for establishing a flow of gas through the gas flow duct from its inlet.

A preferred embodiment of the invention provides a feed mechanism which is readily adaptable to the handling of particulate materials of a variety of types and which maintains a relatively constant or precise stream or flow of the powder or other particulate material, even in situations where the material being handled comprises particles of a variety of sizes, or where the material being handled varies as to particle size at different times in the operation of the equipment.

Another feature of a preferred embodiment of the invention is a particle feed system in which the feed or flow of the particles into a pressurized gas stream will maintain a desired flow rate without excessive fluctuation in the amount of particulate material delivered into the pressurized gas stream, thereby avoiding problems of blockage of flow passages because of excessive fluctuation in the quantity of the material being delivered.

One of the problems encountered in a system for the feed of particulate materials is the problems of establishing a supply or reservoir of the material readily available to the delivery equipment and in which the material is automatically delivered into the flow stream notwithstanding the presence of the particles in a mass or bulk from which the stream of particles is derived and fed to the delivery means.

A preferred embodiment of the invention incorporates not only the particulate feed mechanism itself, but also a special arrangement of a reserve supply container associated with the particle feed device.

The reserve particle supply container is adapted to deliver the reserve supply of particulate material to the feed mechanism in a novel manner.

In accordance with one important aspect of the preferred embodiment, the reserve supply container is of large capacity but is arranged in association with the particle feed mechanism in such manner as to provide for uniform introduction of a stream of the reserve material into the feed mechanism without causing packing or backing up of the particulate material, notwithstanding the large reserve supply available in the reserve supply container.

In accordance with another aspect of the preferred embodiment, provision is made for pressurizing both the feed chamber and the reserve supply container, the pressurization being effected to establish the same pressure in both the reserve supply container and the feed chamber.

In accordance with still another aspect of the preferred embodiment, provision is made for the employment of a particle feed mechanism of very small size when considered in relation to the volume of reserve particulate material available for feed from the reserve supply container. This is achieved by a special arrangement of feed mechanism for controlling the delivery of the particulate material from the reserve supply container into the feed chamber.

Features of the preferred embodiment are defined in the claims hereinafter.

How the foregoing and other objects and advantages are attained will appear more fully from the following description referring to the accompanying drawings, in which: Figure l is a vertical sectional view of a feed chamber and reserve supply container embodying the invention, this view also diagrammatically indicating certain of the electrical and pressure control systems preferably employed; Figure 2 is a top plan view of the equipment shown in Figure 1, this view being taken as indicated by the line 2-2 on Figure 1 and illustrating certain parts in horizontal section; Figure 3 is a horizontal sectional view through the reserve supply container taken as indicated by the section line 3-3 on Figure 1; Figure 4 is a horizontal sectional view of the feed chamber taken as indicated by the section line 4-4 on Figure 1;; Figure 5 is an enlarged fragmentary view showing certain parts of the lid closure mechanism for the reserve supply container, with some elements illustrated in vertical section; Figure 6 is an enlarged vertical sectional view of the helical feed device which is arranged within the feed chamber; and Figure 7 is a horizontal sectional view of the feed device taken as indicated by the section line 7-7 on FigureS.

Figure 1 shows equipment embodying the present invention. The equipment is adapted to feed particulate material, for instance, an abrasive powder, through a gas flow duct 8 which serves to deliver a stream of pressurized gas, for instance, air, with particles dispersed therein, and is adapted to be controlled by the normally closed valve 10 controlled by the solenoid 11. A nozzle, such as indicated at 9, may be employed to deliver the airEabrasive stream to the point of use, such as mechanical or electronic parts requiring controlled abrasion.

As seen in Figures 1 and 6, the gas flow duct 8 extends through the wall 12 of a feed chamber in which a vibratory particle feed device is incorporated. The duct 8 may be downwardly inclined to facilitate flow. This feed device, as shown in the drawings, comprises a cylinder 13 having a closed bottom 14 but being upwardly open at the top of the interior of the feed chamber 12.

As shown in Figures 1 and 4, the feed chamber 12 is closed by an upper lid part 15, the two parts of the container being bolted together, as indicated at 16 in Figures 1 and 4. The cylinder 13 of the feed device is provided on its inner surface with a helical feed groove 17, the lower end of which communicates with the bottom of the cylinder 13 just above the bottom wall 14 thereof and the upper end of which communicates with a feed tube 18 which delivers the particulate material being fed from the helical groove 17 into an upwardly open funnel 19, the bottom of the funnel communicating with the feed or flow duct 8.

The cylinder 13 is ofthevibratorytype of feed mechanism. For this purpose, the device is mounted upon a base 20 comprising part of any of a number of well-known devices for developing a vibratory motion which, in this case, is transmitted to the chamber 13.

Devices 20 operated electrically are well-known, and may be provided with operated current through appropriate circuits, as will be referred to hereinafter.

The vibration generator may be of the type available on the market under the trade name SYNTRON, for instance, Model EB-00. Vibratory equipment of this type serves to generate the vibratory oscillations of the feed chamber 13 and thereby causes the feed of the particulate material from the bottom of the chamber upwardly through the helical groove 17 for delivery to the flow duct 8.

Particulate material for feed from the helical groove 17 to the feed duct 18 is supplied to the chamber 13 from the reserve supply container indicated at 21. This reserve supply container may be of substantial volume so that it will require loading or reloading only at infrequent intervals. The feed is effected from the bottom of the container 21 through a feed tube 22 which communicates with the bottom of the reserve container 21 and extends downwardly to a level close to the inside surface of the bottom wall 14 of the feed chamber 13. The feed tube 22 has a readily separable threaded mounting 22a so that it may readily be removed and replaced by tubes of other sizes adapted to the feed of particulate materials of various types. The space between the lower end of the feed tube 22 and the bottom wall 14 is indicated by the symbols AB.The distance AB will be selected in accordance with the character, especially particle size, of the material being fed.

Attention is now called to the fact that the wall of the reserve supply container 21 converges downwardly, as indicated at 21 b, and the inclination of this converging portion of the container wall will also depend on the character, including especially the particle size of the particulate material being handled. It is contemplated that the angle of the wall 21 b be such that any remaining material in the reserve supply container will be fed downwardly by gravity into the feed mechanism so long as any material remains in the reserve supply container. This angle, therefore, should be related to the "angle of repose" of the material being handled.In other words, the angle of the portion 21 b of the container wall should be sufficiently steep so that the material will not come to rest on the lower wall of the container but will continue to flow into the feed tube 22 and maintain the feed tube full of the particulate material. As examples of the inclination of the wall of the bottom 21b, for particulate material, such as aluminium oxide, having an average particle size of 50 microns, the angle should be about 60 with respect to the vertical. In the case of aluminium oxide having an average particle size of 10 microns, the angle should be about 30 with respect to the vertical.

The spacing AB between the lower end of the feed tube 22 and the bottom wall 14 of the vibratory feed chamber 13 is also related to the angle of repose of the particular material being handled. This spacing (AB) should be sufficient to provide for continued feed of the material onto the upper surface of the bottom 14 of the feed container and thus into the entrance end of the helical groove 17. However, the spacing AB should not be so great as to "flood" the bottom of the feed container and thereby excessively increase the amount of particulate material fed upwardly in the helical groove 17.

The reserve container 21 is adapted to be connected with the underlying feed chamber by means of bolts indicated at 21a. The formation of the reserve container 21 separately from the feed chamber is desirable because this permits substitution of reserve container of different sizes, thereby adapting the equipment to many different uses.

With respect to the reserve supply container, it is further noted that a device, such as indicated at 23, generally of cone shape is desirably positioned in the lower portion of the supply container, the inclined walls of this device having apertures 24 to provide for feed of the particulate material into the lower portion of the reserve supply container and thus into the feed tube 22. This device 23 may also serve to assume a portion of the weight of the supply of material in the reserve supply container.

The reserve container may, if desired, be formed as a cartridge or may be adapted to receive a cartridge, for instance in the manner described in relation to an alternative embodiment disclosed hereinafter.

The feed chamber 12 is supplied with gas, for instance, air under pressure through a connection 25. Similarly, a connection 26 serves to supply gas under pressure to the reserve supply container, and it is preferred that the feed chamber and supply container operate under equalized pressure conditions. This pressure induces the gas flow into the gas flow duct 8 into which the stream of particles is delivered in accordance with the feed rate estab lished by the helical groove 17 in the vibratory feed chamber 13.

Because of the arrangements described above, it becomes possible to charge the overall equipment with a large volume of particulate material without adversely influencing the rate of feed either of the particulate material itself or of the gas introduced into the flow duct 8 for delivery to the point of use.

Because of the handling of the reserve supply of particulate material in the separate upper chamber indicated at 21 and because of the manner in which the material is fed from the reserve supply container through the feed tube 22 into the bottom of the vibratory feed chamber 13, it becomes possible to provide a given rate of feed with vibratory equipment of much smaller size than would be practicable with various other forms of known equipment. In other words, these features make it possible to reduce the size of the vibratory feed chamber and other associated parts.

These features have a further advantage in that particulate material even of very fine particle sizes can readily be handled and uniformly fed, notwithstanding the large overall storage capacity of the equipment.

Before considering the electrical and pneumatic control systems, attention is directed to the structure at the top of the reserve supply container. A lid 27 is provided, being insertable into a circular cavity at the top of the chamber. The lid is provided with latch mechanisms indicated at 28, which mechanisms are adapted to be moved radially in order to engage under an annular ring 29. The action of these latches is adapted to be controlled by a knurled knob 30, or by other suitable mechanism providing for alternative engagement and disengagement of the latches 28 with the ring 29.

As above mentioned, both the feed chamber 12 and the reserve supply container 21 are adapted to be pressurized, and it is preferable that the pressure be equalised in the feed chamber and reserve container. From Figure 1,itwill be seen that the pressure connections 25 and 26 for the chamber 12 and container 21 are interconnected by a pipe 31, thereby assuring that the pressures will be equalized. The system may be supplied with a gas under pressure, for instance, air, in any desired manner, for example, by a supply line diagrammatically indicated at 32, and it is desirable that this supply line be connected with a pressure regulated source of the gas employed. The line 32 is adapted to be connected with the passages 25 and 26 and the interconnecting pipe 31 through a connection 33 having a check valve 34 and also a solenoid control valve 35 therein.The valve 35 is adapted to be operated by the solenoid indicated at 36, and this arrangement provides a normally closed valve openable by the solenoid when the master control for the equipment is turned on.

In a typical case where the equipment is used with an abrasive powder, the pressure in both the feeding chamner and the reserve container may be of the order of 5PSI to 300 PSI, for instance about 85 PSI.

Provision is also made for discharge of the pressurized air from both the chamber 12 and container 21 through a discharge connection 37. This discharge connection may deliver to atmosphere through an exhaust pipe 38 when a valve 39 is open.

The valve 39 is adapted to be controlled by a solenoid 40, and this represents a normally open solenoid valve so that the valve 39 remains open except when the master control is turned on.

The two solenoids 36 and 40 are supplied with current through the control switch diagrammatically indicated at 41. In turn, the control switch 41 receives current through the master power switch generally indicated at 42. The circuits extending from the switch 41 to the solenoids 36 and 40 are also controlled by an automatic shut-off device 43 which is arranged in the lid portion of the container 21 and which is shiftably movable under the influence of one of the latch mechanisms 28. When the control knob 30 is operated to engage the latches 28, the latch which is associated with the automatic shut-off device 43 is shifted to a position in which the circuit through the switch 41 is completed, in order to provide the operating current to the solenoids 36 and 40.When the latches 28 are withdrawn under the action of the control knob 30, the automatic shut-off device 43 prevents current from being delivered to the solenoids 36 and 40. This arrangement automatically prevents introduction of the pressurizing gas when the lid and its latches are not closed.

With the control equipment above described, it will be seen that closure of the master control switch 42 will provide for pressurization of both the chamber 12 and the container 21. When the master control switch 42 is opened, the NC solenoid 36 will close the valve 35, thereby shutting off the supply of compressed air, and the NO solenoid 40 will open the valve 39, thereby providing for bleeding off of the pressure from both of the chamber 12 and the container 21.

The master control switch 42 also controls the delivery of current to certain other devices, including the NC solenoid 11 which controls the delivery of the air/abrasive stream through the gas flow duct 8. This action is under the control of a manually operable switch 44. The switch 44 also controls the delivery of current to a device 45 through which the current is supplied to a vibrator mechanism 46 on which the base 20 for the vibratory cylinder 13 is mounted. The device 45 is in the nature of a control box regulating the intensity of the vibration communicated to the vibratory cylinder 13, and thus regulating the rate of feed of the powdered material into the gas flow duct 8. Because of this arrangement the vibratory feed action occurs only when the delivery duct 9 is open.

It will further be noted that the pressurization of the chamber 12 and the container 21 may be effected independently of actual delivery of the air/abrasive stream, which is desirable, since for most purposes when air/abrasive material is being handled, it is preferred that the pressure desired be preestablished, prior to the time the abrasive particles are used for an actual abrading operation. A time interval is, of course, required to build-up the pressure in the container and chamber, and once this is established, virtually instantaneous action of delivery of the abrasive stream can be effected at will by the operation of the manual control switch 44.

The equipment herein disclosed is adapted to the handling of any of a variety of particulate materials, and is especially suitable forthe handling of abrasive materials of fine or small particle size. Because of the employment of the reserve container 21 in combination with the feed chamber 12, it is possible to charge the equipment with a relatively large volume of the material to be handled, while at the same time permitting miniaturization of the vibratory equipment and the vibratory cylinder 13.

Because of the arrangement of the inclination of the walls 21 a at the bottom of the reserve container and also the arrangement of the cone-shaped device 23 in the lower portion of the container, and still further because of the close spacing of the feed tube 22 to the bottom wall 14 of the vibratory cylinder 13, continued and controlled feed of the particulate material is assured, even from a large volume reserve container, and without excessive build-up at any point in the system, including the interior of the vibratory cylinder 13. With equipment of the kind illustrated and described, when handling an abrasive particulate material, for instance averaging in a range from about 0.3 to 100 microns, the vibratory cylinder 13 may even be reduced in size to about 1 inch (2.54 cm) in diameter, depending on the powder being dispensed.

Equipment embodying the present invention is capable of adaptation in order to handle particulate materials of a wide variety of types, for instance, powders, such as abrasive powders, for example, finely grated aluminium oxide, sodium, bicarbonate or the like. Other abrasive materials can also be handled, including, for example, sand. Moreover, the use of equipment embodying the invention is not limited to the handling of abrasive material, but almost any particulate material, even dirt of particulate rock could be handled. The equipment is especially adapted for use with a gaseous carrier stream for the particulate material; and in a typical case, the gas employed may be air, especially dehydrated air.

In an alternative, simpler embodiment of the invention, the major components of the system include a chamber for receiving the supply of abrasive powder to be delivered to a point of use, the chamber being adapted to operate under pneumatic pressure, and the pressurized fluid being introduced into the chamber through an air supply connection.

Another connection extending from the chamber serves to deliver the stream of pressurized air carrying the abrasive particles therein, and this delivery line extends through a valve which controls the flow to a delivery nozzle. The valve is desirably operated by a solenoid, and this solenoid-operated valve is a Normally Closed valve. Compressed air from the supply source is delivered to the chamber through another valve which is operated by another solenoid and constitutes a Normally Closed valve.

For the purpose of effecting depressurization of the chamber, an exhaust line is connected with the air input connection and delivers through a valve operated by the solenoid, this valve being a Normally Open valve. A check valve is so arranged that upon depressurization of the system through the exhaust line valve, flow will not occur from the chamber into the air supply line.

The air supply valve and exhaust valve are desirably controlled by a common control switch.

The chamber is of special form particularly adapted to effect the feed of a constant stream of powder from a cartridge or powder supply within the chamber into the pressurized air stream which is delivered through the connection. This feed is effected by a vibratory system, the vibrations being initiated by mechanism in the base on which the chamber is mounted. The vibratory base comprises electrical mechanism for initiating the vibrations, and current for operating the electrical vibratory mechanism is delivered from a control box preferably having a control for adjusting the frequency and/or the intensity of the vibration. A manual control switch serves to deliver current from a source of supply both to the control box for the vibratory mechanism and also the NC solenoid of the delivery line valve.With this system, the vibratory feed of the powder material and the opening of the valve are concurrently effected by means of the same manual control switch.

The delivery nozzle may be of any suitable form adapted to the purposes for which the equipment is to be used. Any handpiece having a nozzle can be employed, thereby delivering the abrasive-laden air stream to the desired point of use. It will be understood that for this purpose, it is preferable that the delivery connection include a portion which is of flexible character so that the nozzle may be moved to any desired position in relation to the supply source for the abrasive-laden stream within the chamber.

With respect to the air supply and delivery connections to the chamber, it is desirable that at least a portion of those connections comprise flexible tubes so that the connections will not interfere with the vibratory motions of the chamber during use of the equipment. It is also desirable that those vibratory motions be absorbed in flexible connections so as to avoid communicating such vibrations to the valve mechanisms either on the input side or the output side of the system.

The chamber may conveniently be of generally cylindrical construction having a bottom wall. On the inside of the upright cylindrical wall of the chamber, there is provided a helical feed groove which runs from the bottom to the upper region of the chamber.

This groove is formed by a wall carried on the inside surface of the chamber. The lower end of the feed groove is opened to the bottom area of the chamber, and the upper end of the feed groove is associated with the discharge channel which, in turn, is associated with the delivery connection.

The central portion of the chamber is adapted to receive a cylindrical, open-topped container for a charge of the powder or other particulate material to be delivered. The wall forming the helical groove defines a central compartment in the chamber which receives the container as a replaceable cartridge of powder. This container has a screen mounted in the bottom thereof adapted to be supported in the chamber slightly above the bottom wall thereof. The bottom of the container is also provided with angularly spaced supports which are received between pairs of spaced lugs which project upwardly from the bottom wall of the chamber.These parts not only serve the purpose of supporting the lower wall of the container above the bottom wall of the chamber, butfurtherserve another purpose explained more fully hereinafter with respect to the vibration of the equipment as contemplated for the purpose of feed of the powder material.

A portion of the powder material spreads itself on the bottom wall of the chamber.

The container may be inserted in or removed from the chamberthrough the top thereof by removal of a lid which has a threaded connection with the upper edge of the chamber. If desired, the lid may also be provided with a central aperture which is adapted to be covered by a closure member which is oscillatably movable about the connecting post. A resilient gasket or seal is desirably positioned between the closure member and the lid, in order to prevent pressure leakage when the system is charged and in use. The closure member may be swung to one side, and when in position to close the central aperture in the lid, may be fastened by any appropriate locking device.

The base on which the chamber is mounted comprises any of a number of well-known devices for developing a vibratory motion which, in this case, is transmitted to the chamber. A power connections is provided between the base and the control box. The control box is provided with appropriate control devices of known type to regulate the vibratory motion.

The vibration generator may be of the type with the trade name SYNTRON, for instance, Model EB-OO. The vibration generator causes oscillation of the chamber substantially about its vertical axis.

With this type of vibratory action, the powder material which is discharged from the container onto the bottom surface of the chamber enters the entrance end of the helical groove; and the vibratory oscillation of the chamber results in progressive feed of the powder material upwardly in the helical groove for ultimate delivery through the discharge channel which communicates with the delivery connection. Since the system is pressurized during operation, this feed of the powder through the discharge channel into the delivery connection results in entrainment of the powder in a stream of the pressurized air or other gas.

As a preliminary to conditioning the equipment for operation, the control switch will be closed, thereby opening the NC solenoid valve in the air supply line and closing the NO solenoid valve in the exhaust line. This will result in build-up of the appropriate pressure in the system. After the system has been pressurized, and at the time when the operator desires to deliver the air/abrasive stream from the nozzle, the operator closes the switch which concurrently opens the NC solenoid valve in the delivery line and delivers current through the control box to the vibration mechanism. Thus, the control switch automatically interrelates the operation of the nozzle and the feed of the abrasive material into the pressurized stream of air.Similarly, when the control switch is opened, the NC solenoid valve in the delivery line will be closed and, concurrently, the vibration will be terminated. This is important as it is desired to have the feed effected only at the time when the flow of material is being discharged from the equipment.

At a point in the use of the equipment, for instance, when it is desired to reload the container in the chamber, the control switch may be opened, thereby closing the NC solenoid valve in the air supply line and opening the NO solenoid valve in the exhaust line. This will result in bleeding of the pressure from the system through the exhaust line, after which the chamber may be opened, for instance, by displacing the closure plate or removing the lid.

The control for the vibratory action of the base will be employed to regulate the quantity of the material being delivered into the gas stream. Such a control may provide either for regulating the intensity or the frequency, or both, of the oscillative vibratory action.

As above noted, it is contemplated that the supply and delivery connections be flexible so as not to interfere with the vibratory action of the feed mechanism.

Depending upon the particulate material being handled, the equipment is adapted to serve many purposes, for instance, delicate dental operations, including abrasive jet etching or dental prophylaxis.

The equipment may also be used for may industrial purposes, such as resistor trimming and heatless and shockless cutting of a wide variety of hard brittle materials, such as germanium, silicon, mica, glass, fragile crystals and ceramics. For many purposes, including dental prophylaxis and tooth restorations, the particulate material employed may constitute a soft powder suitable for polishing delicate surfaces.

For all of the foregoing and other purposes, the invention is of special advantage because of the fact that uniform and accurate feed of the particulate material is provided for. It is also of importance that the rate of feed may readily be adjusted by control of the vibratory oscillation.

Because of the foregoing capabilities, the present equipment may be employed for a much broader range of uses than other systems heretofore proposed.

The uniformity of flow provided by equipment embodying the invention eliminates the difficulties and disadvantages incident to various prior systems which were characterized by erratic flow or spurting of the abrasive or other particles being delivered.

In addition to the employment of air, other gases may be used, including carbon dioxide and also various chemically inert gases.

In a typical system according to the invention, with a SYNTRON feeder of the type above mentioned, the vibrations of the container may occur at a rate of about 3600 vibrations per minute, but other rates are usable, for instance, in the range from about 1200 vibrations per minute to about 24,000 vibrations per minute. The rate of vibration employed will depend somewhat upon the character of the material being handled and also upon the volume of material desired to be delivered.

In a typical application of the equipment to abrasive action with a fine powder, for instance, a powder having particle sizes running from about 1:2 micron to about 200 microns, a delivery nozzle having a bore of about 0.005" to about 0.125", for instance, 0.018" may be used. In such use, the pressure may be from 5 psi to about 250 psi, for instance, about 80 psi.

Another advantageous characteristic of the arrangement of the invention is the fact that substantial uniformity and accuracy of feed of the particles may be achieved, even in circumstances where the powder being delivered has a relatively broad range of particle sizes.

Relatively soft powders, such as sodium bicarbonate or calcium carbonate, may be employed for various dental purposes. Calcium carbonate is preferably of crystalline form and may be derived, for example, from iceland spar or from fresh water clam shells, or high grade silicate-free white marble. The equipment may be used for a wide variety of purposes in dental work, including not only polishing and abrading, but in order to provide accurate occlusial articulation in dental porcelain, and this has not been practicable heretofore. Other uses may also be served including for the purpose of deburring gold crowns and cleaning dental castings; and for many of these purposes, a change of nozzle would be the only required alteration in a given equipment set-up.

The pitch of the helical groove is an important characteristic in the equipment of the invention, and this pitch may vary over a rather broad range, even for a powder of a given type. Thus, a pitch of from about 1 1/2 degrees up to about 30 degrees may be used for various purposes and various different powder materials. The diameter of the chamber 6 may also vary, in a typical case being from about 1 to about 12 inches; with a chamber in the range indicated, the width and depth of the helical groove may vary all the way from about 1:32 x 1/32 inch up to about 1 1/2 x 1 112 inches.

Claims (32)

1. Apparatus for feeding particulate material into a gaseous stream, comprising a gas flow duct having an inlet, a vibratory feed chamber adapted to feed a stream of particulate material into the inlet of the gas flow duct, the wall of the feed chamber being mounted for vibratory movement, and means for establishing a flow of gas through the gas flow duct from its inlet.

2. Apparatus for feeding powder particles into a gaseous stream, comprising a pressurized powder chamber, means defining a helical powder feed channel with its inlet end in a lower portion ofthe chamber and inclined upwardlyto an upper portion of the chamber, mechanism for vibrating the chamber and the powder feed channel therein to effect upward feed of the powder particles in the channel, and a gas flow duct having an inlet in communication with the chamber in a region adjacent the upper end of the helical feed channel.

3. Apparatus as defined in claim 2, in which the feed channel is open to the interior of the chamber, the apparatus further including a pressureized gas inlet communicating with the chamber and providing a pressurized gas supply in the chamber for delivery through the said gas flow duct.

4. Apparatus as defined in claim 2, in which the powder chamber has a compartment located centrally of the helical powder feed channel for receiving a replaceable cartridge of powder to be delivered to a lower portion of the feed channel.

5. Apparatus as defined in claims 2 and further including means for delivering a supply of powder into the lower portion of said chamber in the region ofthe lower end ofthe helical channel.

6. Apparatus for feeding powder particles into a gaseous stream comprising a generally cylindrical powder chamber positioned on an upright axis, means on the inside wall of said chamber defining an upwardly open helical powder feed groove with its inlet end in a lower portion of the chamber and inclined upwardly to an upper portion of the chamber, mechanism for vibrating said chamber and the powderfeed groove to effect upward feed of the powder particles in the groove, and a gas flow duct having in an upstream region thereof an inlet communicating with the powder feed groove.

7. Apparatus for feeding abrasive particles into a gaseous stream and for delivering the abrasiveladen stream to a target area to be abraded, comprising a powder chamber, means defining a helical powder feed channel with its inlet end in a lower portion of the chamber and inclined upwardly to an upper portion of the chamber, mechanism for vibrating said chamber and the powder feed channel therein to effect upward feed of the powder particles in the channel, a gas flow duct having an inlet communicating with the helical powder feed channel in a region in the upper portion of the chamber, and a nozzle connected with said duct to receive abrasive-laden gas therefrom when the vibration mechanism is activated.

8. Apparatus for feeding a stream of particulate material comprising a chamber defined by a wall mounted for vibratory movement, the chamber being closed and having means for introducing a pressurized gas, supply means for delivering particulate material into a lower region of the chamber, a pressurized gas discharge connection communicating with an upper portion of the chamber, and means defining a helical particle feed channel extended from the lower region of the chamber upwardly to the discharge connection, thereby providing for feed of particulate material into the discharge connection.

9. Apparatus as defined in claim 8, in which the material supply means comprises a replaceable cartridge having delivery means in the bottom thereof for delivéring the material into the bottom region of the chamber.

10. Apparatus as defined in claim 8, in which the material supply means comprises a material container having means for delivering the material downwardly, the apparatus further including means interconnecting the chamber and the material supply means and providing fortransmission of vibratory movement from the chamber to the material container.

11. Apparatus as defined in claim 8 and further including an electrically activated means for vibrating the chamber, pneumatic means for delivering the particulate material from the helical feed channel to a point of use, and common control means for the electrically activated means and for the pneumatic means.

12. Apparatusforfeeding abrasive powder particles into a gaseous stream and for delivering the abrasive laden stream to a target area to be abraded, comprising a powder chamber, means for delivering a pressurized gas into the powder chamber, means defining a helical powder feed channel with its inlet end in a lower portion of the chamber and inclined upwardly to an upper portion of the chamber, mechanism for vibrating the powder feed channel to effect upward feed of the powder particles in the channel, a delivery duct having an inlet communicating with the helical powder feed channel in a region in the upper portion of the chamber to receive a pressurized stream of abrasive-laden gas, and a nozzle connected with the duct to receive abrasiveladen gas and deliver the abrasive-laden gas to a point of use.

13. Apparatus as defined in claim 12 and further including a pressurized gas supply system including a normally closed solenoid-operated valve for delivering pressurized gas into the powder chamber, and a normally closed solenoid-operated valve in the delivery duct.

14. Apparatusforfeeding powder particles into a gaseous stream comprising a powder chamber, means defining a helical powder feed channel with its inlet end in a lower portion of the chamber and inclined upwardly to an upper portion of the chamber, mechanism for vibrating the chamber and the powder feed channel therein to effect upward feed of the powder particles in the channel, a system for pneumatically pressurizing the chamber comprising a pressurized gas inlet communicating with the chamber and having a normally closed control valve, an exhaust connection communicating with the chamber and having a normally open control valve, common control means for the normally open and normally closed valves and providing for concurrent operation thereof in opposite senses, and a gas delivery duct for delivering a stream of gas and suspended particles from the chamber and having an inlet in communication with the chamber in a region adjacent the upper end of the helical feed channel.

15. Apparatus as defined in claim 14 and further including a control valve in the gas delivery duct, and control means for concurrently closing the control valve and deactivating the mechanism for vibrating the chamber.

16. Apparatusforfeeding particulate material into a gaseous carrier stream, comprising a gas flow duct having an inlet, a vibratory feed chamber adapted to feed a stream of particulate material into the inlet of the gas flow duct to provide for carrying the particulate material in a stream of gas in the flow duct, a container for a reverse supply of particulate material, and a feed tube for delivering material from the container into the vibratory feed chamber, the feed tube being extended into the feed chamber to deliver particulate material against a wall of the feed chamber, and the wall of the feed chamber being mounted for vibratory movement independently of the feed tube.

17. Apparatus for feeding particulate material into a gaseous carrier stream, comprising a gas flow duct having an inlet, a pneumatically pressurized receptacle in which the inlet of the flow duct is exposed, a vibratory feed chamber in said pressurized receptacle, the feed chamber having means adapted to feed a stream of particulate material into the inlet of the gas flow duct to provide for carrying the particulate material in a stream of gas in the flow duct, a container for a reserve supply of particulate material, and a feed tube for delivering material from the container into the vibratory feed chamber, means establishing substantially the same pneumatic pressure in the container as in the pressurized receptacle, the feed tube being extended into the feed chamber to deliver particulate material against a wall of the feed chamber, and the wall of the feed chamber being mounted for vibratory movement independently of the feed tube and of the container.

18. Apparatusforfeeding particulate material into a gaseous carrier stream, comprising a gas flow duct having an inlet, a pneumatically pressurized receptacle in which the inlet of the flow duct is exposed, a vibratory feed chamber in the pressurized receptacle, the feed chamber having means adapted to feed a stream of particulate material into the inlet of the gas flow duct to provide for carrying the particulate material in a stream of gas in the flow duct, a container for a reserve supply of particulate material, means interconnecting the container and the chamber and providing for delivery of material from the container into the chamber, and means establishing substantially the same pneumatic pressure in the container as in the pressurized receptacle.

19. Apparatus as defined in claim 18 and further including means for concurrently pressurizing the feed chamber and the container.

20. Apparatus as defined in claim 18 and further including a removable cover for the container, pneumatic means for retaining the cover in closed position, and means interrelating the operation of the pneumatic means and the means establishing the pneumatic pressure in the container and providing against opening of the cover when the container is pressurized.

21. Apparatus as defined in claim 18 and further including valve means in the flow duct for carrying the particulate material in a gas stream, and control means for the valve means providing for selective opening and closing of the valve means when the receptacle is pressurized.

22. Apparatus for feeding particulate material into a gaseous stream comprising a pressurized chamber, means defining a helical powder feed channel with its inlet end in a lower portion of the chamber and inclined upwardlyto an upper portion of the chamber, mechanism for vibrating the chamber and the feed channel therein to effect upward feed of the particles in the channel, a gas flow duct having an upwardly presented inlet, and a conduit having one end positioned to receive particulate material from the feed channel and the other end positioned to deliver particulate material into the upwardly presented inlet of the gas flow duct.

23. Apparatus as defined in claim 22 in which the inlet end of the flow duct comprises an upwardly flared funnel, and in which the delivery end of the conduit extends downwardly into said funnel.

24. Apparatus for feeding particulate material into a gaseous stream comprising a generally cylin drical particle feed chamber positioned on an up right axis, mearis in the chamber defining a helical particle feed groove with its inlet end adjacent to the bottom wall of the chamber and inclined upwardly to an upper portion of the chamber, mechanism for vibrating the chamber and the particle feed groove to effect upward feed of the particles from the bottom of the chamber upwardly in the groove, a gas flow duct having an inlet in an upstream region thereof, with the inlet communicating with the particle feed groove and providing for delivery of a stream of gas and particles, a reserve particle supply container above the feed chamber, and a feed tube extended downwardly from the reserve supply container into the feed chamber with a delivery opening in the region of the bottom of the feed chamber, the feed chamber being mounted for vibratory movement independently of the feed tube.

25. Apparatus as defined in claim 24 in which the delivery opening of the feed tube is spaced above the bottom of the feed chamber at a distance sufficient to pass the particles being delivered but not sufficient to permit free unlimited particle flow.

26. Apparatus as defined in claim 25 and further including a receptacle surrounding the feed chamber, and means providing for pneumatic pressurizing of said receptacle and the containerforthe reserve powder supply.

27. Apparatus for feeding particulate material into a gaseous stream comprising a generally cylindrical particle feed chamber positioned on an upright axis, means in the chamber defining a helical particle feed groove with its inlet end adjacent to the bottom wall of the chamber and inclined upwardly to an upper portion of the chamber, mechanism for vibrating the chamber and the particle feed groove to effect upward feed of the particles in the groove, a gas flow duct having an orifice in an upstream region thereof, with the orifice communicating with the particle feed groove and providing for delivery of a stream of gas and particles, a generally cylindrical reserve particle supply container above the feed chamber, and a feed tube extended downwardly from the reserve supply container into the feed chamberwith a delivery opening in the region of the bottom of the feed chamber, the feed chamber being mounted for vibratory movement independently of the feed tube, the bottom of the reserve supply container having a converging wall with the feed tube associated with the bottom thereof, and the angle of convergence of the bottom wall being smaller than the angle of repose of the particulate material being handled, so that the entire reserve supply may be fed downwardly under the influence of gravity into the feed tube

28.Apparatus as defined in claim 27 in which the reserve supply container is adapted to receive a bag containing a charge of the particulate material and having a rupturable bottom, the apparatus further including a bag rupturing device in the lower portion of the supply container above the feed tube.

29. Apparatus as defined in claim 27 and further including a pneumatically pressurized receptacle surrounding the feed chamber, and means for pneumatically pressurizing the reserve supply container and providing for equalization of the pressure in the receptacle and the container.

30. Apparatus for feeding particulate material into a gaseous stream comprising a generally cylindrical particle feed chamber positioned on an upright axis, means in the chamber defining a helical particle feed groove with its inlet end adjacent to the bottom wall of the chamber and inclined upwardly to an upper portion of the chamber, mechanism for vibrating the chamber and the particle feed groove to effect upward feed of the particles from the bottom of the chamber upwardly in the groove, a gas flow duct having an orifice in an upstream region thereof, with the orifice communicating with the particle feed groove and providing for delivery of a stream of gas and particles, a reserve particle supply container above the feed chamber, the reserve container having a downwardly converging side wall at an angle steeper than the angle of repose of the particulate material being fed, and a feed tube extended downwardly from the apex of the bottom of the reserve container for delivery of the particulate material to the bottom of the feed chamber, the feed chamber being mounted for vibrating movement independently of the feed tube.

31. Apparatus as defined in claim 30 and further including a conical perforated wall in the lower portion of the reserve container, with the apex of the cone presented upwardly.

32. Apparatus for feeding particulate material into a gaseous stream, substantially as described hereinbefore with reference to the accompanying drawings.