US 3442454 A
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y 1969 H. STENGER ET AL POWDER SUCTION DEVICE orz Sheet Filed April 15, 1966 y 6, 1969 H. STENGER ET AL 3,442,454
POWDER SUGTION- DEVICE Filed April 15, 1966 Sheet 2 Of 2 United States Patent 3,442,454 POWER SUCTION DEVICE Herbert Steuger, Schwarzenbruck, Manfred Strossner,
Nuremberg, and Friedrich Wendler, Erlangen, Germany, assignors to Siemens Aktieugesellschaft, Er-
langen, Germany Filed Apr. 15, 1966, Ser. No. 542,897 Claims priority, applicgtiou Gsrmany, Apr. 17, 1965, 96 6 Int. Cl. BilSb 7/30 US. Cl. 239-85 7 Claims ABSTRACT OF THE DISCLOSURE Our invention relates to powder suction device, and more particularly to such devices for use with flame spray guns.
Linings or coatings and shaped members can be formed by spraying solid materials with flame spray guns and plasma burners or plasma spray guns. Plasma spray guns also now for the first time permit processing or working, by spraying, of materials such as tungsten, which are tough materials and difficult to melt. Also, by means of plasma spray guns, close adhesion of the sprayed material to the base or core on which it is sprayed is achieved, a result which had not heretofore been so easy to obtain. When employing such spraying technique, the material which is to be worked is conventionally supplied to the flame or plasma beam in powder form. Exceptional difliculties have been encountered, however, in supplying a continuous flow of powder to the gas flame or the plasma beam. Of particular importance is the fact that the plasma spray guns are especially sensitive to a non-uniform feeding of the powder. For practical operation it is furthermore often essential to control the quantity of powder independently of the respective operating condition of the spray gun.
Multifarious systems of operation for powder suction devices have already been developed heretofore. Thus, in a well known plasma spray gun the powder is forced out of the powder receptacle, at a slight overpressure, by vibratory motion through a sieve or screen in a tube into the channel of the burner. Such devices wherein the powder is fed to the burner channel only under pressure, tend to clog the supply conduit particularly easily. With another type of powder supply, the powder receptacle is located above a screw or worm conveyor which conveys the pulverulent material mechanically to the spray gun. In actual practice, devices which suck the powder out of a powder receptacle in accordance with the jet pump principle have particularly been tested and tried. In principle they comprise a closed powder supply hopper from which, with pressure equalization through a standpipe or ascending tube, the powder is removed by suction through a jet pump by means of a gas current. All of the a-foredescribed devices of the known art have the disadvantage that the working material supplied into the powder receptacles and flasks must be emptied into the powder supply hopper of the supply :device and that for 3,442,454 Patented May 6, 1969 working processes requiring several different materials, many of such devices must be provided accordingly. Furthermore, one must also consider the disadvantage resulting from the fact that the powder supply hoppers must be emptied and cleaned very often.
Also, the method previously found successful in the laboratory of sucking the powder out of open shells or cups has not proven to he too successful in actual practice because it is dependent upon manual skill as to whether the suction conduit is to provide a uniform powder current flow or become clogged.
It is accordingly an object of our invention to provide powder suction device which will avoid the disadvantages of the aforementioned devices known heretofore.
It is furthermore an object of our invention to provide powder suction device which will safely suck powder directly from conventional powder receptacles o-r flasks during operation.
With the foregoing and other objects in view we provide powder spray device comprising a jet nozzle leading to a spout opening formed in a nozzle head mounted on the powder receptacle. For those powlder receptacles which do not have a venting hole, a branching bore to the gas channel is provided upstream of the jet nozzle, an ascending tube or standpipe being inserted in the branching bore.
Further in accordance with our invention, the powder suction device can be quite readily interchanged so that it is available for immediate use. The nozzle head can be provided with a suitable thread so that it can be directly screwed with conventional threading means immediately on correspondingly threaded conventional powder flasks. When in operation, the flask is merely placed on the nozzle head so that the neck of the flask is located on the base of the nozzle head and is provided with the connecting conduits. With the device constructed in accordance with our invention, the supply of spray material is continuously adjustable. The powder flask can be placed under a protective gas atmosphere and can 'be fed by suction and/or under pressure to the burner.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in powder suction device, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings, in which:
FIG. 1 is a side view partly in section of a powder flask on which a nozzle head has been mounted in operating position, i.e., with the flask inverted;
FIG. 2 is a sectional view of a slightly modified embodiment of the nozzle head of FIG. 1;
FIG. 3 is a sectional view of another embodiment of the nozzle head; and
FIG. 4 is a diagrammatic view of an adapter ring which permits the nozzle head of FIGS. 1 to 3 to be screwed onto a powder receptacle having a threaded neck of larger thread diameter than that of the nozzle head.
Referring now to the drawing and first particularly to FIG. 1 thereof, there is shown a powder suction device proper which is formed of a powder flask 1 and a nozzle head 2 capable of being threaded on the flask 1. The nozzle head is provided with a tubular nipple 3 by means of which the nozzle head is connectable to a supply tube of a spray gun (not shown). It the supply tube to the spray gun is under suction, the other nipple 4, as shown in FIG. 1, can remain open to admit air or can be connected to a container of a specific gas when the specific gas only is to be sucked into the spray gun. For other types of spray guns, a suitable gas can be supplied under pressure to the nozzle head 2 through the nipple 4. The standpipe or ascending tube communicates with the nipple 4 and provides pressure equilization in the powder receptacle 1. By means of the two bends in the lower end of the standpipe 5 as shown in FIG. 1, the main portion of the standpipe 5 can be placed in a central location in the receptacle 1. The standpipe 5 ends in a pointed dome to prevent its being clogged when it is inserted into a powder flask filled with powder. The gas or air which is admitted through the nipple 4 passes through the vertical tube 5 and is discharged through lateral gas outlet openings 7 (only one of which is shown in FIG. 1) formed in the vertical tube 5.
A detailed description of the nozzle head 2 will now be given with respect to the embodiment shown in FIG. 2. The nozzle head 2 comprises a base ring 8 formed with an axially extending funnel or hopper 9 which acts as a spout opening for the flask 1, and furthermore comprises an annular rim 10 in which an inner thread 11 is provided, for threading therein powder flasks having a corresponding outer thread. The base ring 8 and the annular rim 10 are secured to one another by press-fitting an anular sleeve portion of the annular rim 10 into an annular recess of the base ring 8 so that the base ring -8 and annular rim 10 abut against each other at their mutually engaging shoulders 14. A sealing ring 13 is interposed between the base ring 8 and the anular rim 10. It is of course also posible to provide mutually threadable screw threads on the respective shoulder locations 14 of the base ring 8 and the annular rim 10 instead of press-fitting those members together. The neck of the powder flask is threaded in an annular groove 15 located between the outer surface of the funnel 9 and the innersurface of the annular rim 10, and is sealed by the sealing ring 13 and the connection between the base ring 8 and the annular rim 10 at 14. The side or wall of the funnel 9 consequently protects the thread 11 from being soiled.
A radially extending bore 16 is provided in the base ring 8, and a jet nozzle 17 and discharge tube 18 are inserted in the bore 16 which forms a gas channel with which a branching bore 19 communicates. As shown in FIG. 1 the ascending tube 15 is inserted in the branching bore 19. The discharge tube 18 which is made of a material selected with regard to its compatibility with the chemical substances passing therethrough, is adjustable in the axial direciton of the gas channel by means of the knurled screw 20 which is threadable axially of the gas channel so as to move the discharge tube 18 in either axial direction. Thus the cone 21 of the jet nozzle 17 can be inserted to a lesser or greater extent into the discharge tube 18 so that the annular suction gap 22 in the powder funnel 9 is adjustable in width between the nozzle 17 and the discharge tube 18.
The quantity of powder sucked out of the tunnel or hopper 9 is thereby able to be continually controlled or regulated. The discharge tube 18 is sealed with respect to the wall of the radial bore 16 by a sealing ring 23, consisting for example of rubber.
The knurled screw 20 is provided with a central bore so that it can be mounted circumferentially on the discharge tube 18. The centrally bored screw 20 extends between the shoulder of an annular head or extension 25 formed on the discharge tube and a spring washer 26 abutting against one of the shoulders formed on the nipple 3. By this construction, the discharge tube 18 is movable in the axial direction of the channel when the knurled screw 20 is screwed into or out of the base ring 8 by means of its threaded neck 27 which is engageable in the internally threaded walls of the bore mechanism such as has been afordescribed herein with regard to the discharge tube 18, e.g. with a knurled centrally-apertured screw 30 threaded in a cooperating thread for-med in the base ring 8. The shut-off cone 29 is not provided with a bore extending in the axial diretcion thereof but rather has radially extending lateral openings 31 formed therein for conducting the gas or air which is admitted to the nipple 4. It the knurled screw 30 is turned so that the shut-01f cone 29 is extended into the bore of the jet nozzle 17, the jet nozzle 17 is thereby closed and the path of the working gas between the tubular nipples 4 and 3 is diverted through the powder receptacle 1. The powder is then not sucked out of the powder receptacle, but rather, is entrained with the gas flow out of the pouring funnel or hopper 9. If the knurled screw 30 is turned in the opposite direction so that it is unscrewed and the shut-01f cone 29 is moved axially toward the right side of FIG. 3 so that the bore of the jet nozzle 17 is open, the operation of the embodiment shown in FIG. 3 will correspond to the operation of the embodiment shown in FIG. 2.
By means of intermediate or adapter rings such as is shown in FIG. 4, the nozzle head constructed in accordance with our invention can be employed also with powder receptacles having an externally threaded neck wherein the thread thereon has a greater diameter than the internal thread of the nozzle head. Thus, the thread 33 on the adapter ring 35 can be screwed into the thread on the neck of the powder receptacle, and the thread 32 of the adapter ring can be screwed into the corresponding thread of the nozzle head. A funnel-shaped rim 34 protects the thread 33 from being soiled and a sealing ring 35 is provided at the base of the thread 33 in the adapter ring so as to provide a sealed connection between the adapter ring and the powder receptacle. If the thread 32 has a greater diameter than the thread 33, then nozzle heads constructed in accordance with our invention can be employed for powder receptacles having necks whose thread has a smaller diameter than the diameter of the thread in the nozzle head. Instead of the adapter shown in FIG. 4, for example, the embodiment of FIG. 2 can be so constructed that annular rims 10 of respectively different internal diameters, and consequently having internal threads of respectively different diameters, can be interchangeably fitted or threaded in the base ring 8.
With the nozzle head of this invention it is solely necessary to maintain a pressure difference of the gas flow between the tubular nipples 4 and 3. Consequently, gas or air can be supplied under pressure to the nipple 4, or suction can be applied to the nipple 3.
1. Powder-feeding device for extracting powder from a receptacle by jet-pump action, comprising a nozzle head member formed of a base ring and an annular rim secured to said base ring, said annular rim including means having an internal thread for screwing said nozzle head member into an external thread formed on the receptacle so as to attach said nozzle head member to the receptacle, said base ring having a funnel-shaped recess forming a spout opening extending coaxially to said base ring, said spout opening being in communication with the interior of the receptacle when said nozzle head member is attached to the receptacle, radially extending inlet and outlet gas channels formed in said base ring and communicating with said spout opening, jet nozzle means disposed in said inlet gas channel, and a discharge tube disposed in said outlet gas channel.
2. Powder-feeding device according to claim 1 wherein said nozzle head member is formed with a bore branching off from said inlet gas channel, the powder-feeding device also including a tube received in said branching bore and extending into the powder receptacle, said tube being adapted to equalize the pressure in the receptacle and in said gas channel.
3. Powder-feeding device according to claim 2 wherein said tube is formed with a plurality of bends at the end thereof received in the branching bore of said nozzle head so as to centrally locate the greater portion of said tube in the powder receptacle, the free end of said tube being in the form of a pointed dome and said tube being formed with at least one lateral opening.
4. Powder-feeding device according to claim 2, including a shut-off element in said inlet gas channel at a location between said jet nozzle means and said branching bore, said shut-01f element being adapted to close said jet nozzle means so that the gas in said channel is passed from said gas channel solely through said equalizing tube.
5. Powder-feeding device according to claim 1 wherein said annular rim is exchangeable, and sealing means is disposed between said annular rim and said base ring for sealingly securing them together, said powder receptacle being formed with a thread surrounding said opening thereof and said annular rim being formed with an external thread corresponding to an internal thread formed in the receptacle for directly screwing said powder receptacle and said nozzle head member together.
6. Powder-feeding device according to claim 1, including an adapter ring for fitting said powder receptacle and said nozzle head member together.
7. Powder-feeding device according to claim 6 wherein said nozzle head member is formed with a thread having a given diameter different from the diameter of the thread formed on the powder receptacle, and said adapter ring is provided with a first threaded portion corresponding to the thread on the powder receptacle and with a second threaded portion corresponding to said thread formed on said nozzle head member, whereby said first threaded portion of said adapter can be screwed to said powder receptacle and said second threaded portion of said adapter can be screwed to said nozzle head member so as to securely mount said nozzle head member on said powder receptacle.
References Cited UNITED STATES PATENTS 968,350 8/1910 Harrison 266-23 1,756,381 4/1930 Pahl 239 2,181,095 11/1939 Ness 30253 2,327,337 8/1943 Burch et a1 30253 2,786,779 3/1957 Long et a1. 23985 X 3,281,078 10/1966 Cape 23985 M. HENSON WOOD, JR., Primary Examiner.
HOWARD NATTER, Assistant Examiner.
US. Cl. X.R.