US2953875A - Dry honing device - Google Patents

Description

Sept. 27 1960 w. H. MEAD 2,953,875

DRY HONING DEVICE Filed Dec. 3, 1957 nap I uana,

INVENTOR. FIG.

- LJ/LL/AM. H. EAD

BY :5 W a ATTORNEY United States Patent My invention relates to improvements in .means .for

efluidizing any powdered or finely ground material to. facilitate its rbeingfedrinto an airstream while atthesame time separating ,from the material .any heavier particles which :it .may have picked up.

I shall describe .the application of .my invention as a dry powder .feeder .and separator in .a .dry honing .device. By dry honing device, .I .mean .a mechanism which employs an air Stream into which .a metered amount .of .a -.dry powdered .abrasive is -fed and then impelled by the force of the .air stream against a surface .tobe cleaned -.or .otherwisetreated. s a

My invention was directed at first to :solving .a problem existing in the tool and die art where :in finishing a :die

[it :is blasted-to smooth out the grinding vlines. .Anunex- .pected advantage of my invention that in'addition to erasing the ggrindinglines, the action-of the dry abrasive provided countless tiny pockets in the die parts rinwhkh zlubricant is retained, .with .a resulting-longer ,life of idl die.

Another advantage -.of my invention rlies in its use in deburring tools and machine ,parts vhaving intricate passageways which in the past served as'traps .for the abrasive which was used in a-slurry (wet form ina fluidetreamt).

The slurry would pack in corners :and crevices, ,makingit practically impossible ,to remove it. The time spent in blowing, washing and scrubbing the part was long and tedious and never completely e'fiective.

A further advantage of being abletoifluidize thezabrasive and to use it in dry form is,that.a.vacuum,pickeuprof the spent abrasive can be used to get a continuous re-use of the abrasive. This pickup was not possible with slurry honing.

Another advantage of being able to fluidize the abrasive prior to its re-entry into the air stream is that the debris can be settled out and not be recirculated.

Other objects and advantages of my invention will be apparent from the following disclosure of a preferred embodiment of the device. This disclosure is made in compliance with the statute and is not intended to limit the form of the parts which may be varied by different manufacturers.

In the drawings:

Fig. 1 is a diagrammatic view of the parts comprising the invention, in the environment of an air blasting device, and

Fig. 2 is an exploded view of certain of the parts.

In Fig. l, a hopper 10 is shown positioned above the feeder fluidizer parts which are in the area at the bottom of the hopper. The hopper 10 contains a load of finely ground abrasive which, depending upon the work to be done, may be anywhere from 325 mesh to 5000 mesh.

The feeder-fluidizer includes the feed valve housing 11 with a feed T 12 extending vertically through it and terminating at an orifice 13 in the bottom of hopper 10. The end 14 of the T is connected by the conduit 15 I ice with thetop of the hopper 10. The other end 16 is :connected to the vacuum source "(not shown) and beyond that to'the blasting gun or nozzle (shown in dotted'l-ines). Thisproduces a flow of air in thedirection ofgthe arrow .17 which willp'ick up any abrasive particles Whichtravel downthe leg '18 of .the TI v A vacuum is maintained in the hopper 10 which means that the area 20 in the housing 11 is also under reduced pressure. An air inlet "21 is provided into the housing '11, with a suitable silica-gel moisture trap 22 to-dry the entering the housing. The .size of the inlet 21 "is fixed to give the air flo,w necessary to fluidize and *to separate the dry abrasive in the hopper "10.

Supported in the housing 11 is a porous stone partition 23 with a close fit both against the wall of the .housing at ,its periphery, and at 24 where ;the leg 18 of the T extends through it. The porosity of the stone is such ,that'ior the vacuum maintained in the hopper 10, enough air .will flow upwardly through the stone (see arrows in fig. 2) to fiuidize the fin powdered abrasive in the bot- 'gtom of 1116 hopper 10'. A form of porousstone'i have found useful is jknown on the market as a rosin .guartz vfilter, a product of ,Filtros, Inc., Rochester, NewfYork.

fThe porosity according to the manufacturers description is medium :fine porosity. T his works well With.-a11 aluminum oxide abrasive of a wide range in particle size.

As aresultoi beingffluidizedthe abrasive li r lly fiows -fhrough the orifice13into the feed T at ;12. From there ,theabrasive goes tothe'hlast nozzle ,audiis picked up, as

spent abrasive, by the suction line 25 connectedftov the .cyclone26 and thesuction pump 27. The ,spent abrasive 'hasiinitsome debris which its imp t with the work. sur Iaeereinoyed. 'Largenparticbs of dehrisarett pped on the screen 28 and the smaller particles remain intermingled with the abrasive powder whieh fallsthroughgthe screeninto.thehQmlerlo.

My invention acc mplishes he removal ;from .th'ea asive of .these smaller parti le of debris by having th ai .pervions stone .23 com ine with the orifi e1 which i spacedabove thesuriace o'f theston 13. What app ar ;to;hannen; is that the .air .on leaving the stone .23 b bbles .throughthe abrasive and debris .caus'ingthe latt r to. e e flower in the.hopper10j'intojthearea below the level or the .orjifice 13. The net result isthat the abrasive entering the orificem 'is-subs'tantia'lly cleaned and is only contaminated with debris to the extent of the relative area of the orifice 13 to the area of the housing 11. If these relative areas are 1 to 100, then it means the abrasive will be about 99% cleaned. This slight contamination is because the debris over the orifice 13 will settle into the tube while the other debris is settling into the areas below and beside the orifice 13.

A spring 30 encircling the tube 18 will hold the porous stone 23 in a snug fit on the bottom of the hopper 10.

The above described device thus accomplishes an aeration of fluidizing of the abrasive-debris mixture in the hop per 10, and the difference in specific gravity of the debris and of the abrasive causes the debris to settle out of the aerated abrasive. This settling-out can go on efiectively until the area in the hopper below the orifice 13 becomes filled with debris at which time the machine is stopped and the parts separated to remove the accumulated debris. This suggests that the orifice 13 should be put at a height which will give the desired length of operating cycle between cleanouts.

Briefly summarized, the operation of my device is as follows: The hopper 10 is filled with a dry powdered abrasive suitable to the job to be done. A vacuum is applied to the line 16 to draw the abrasive to the blast gun. This same vacuum, through pipe 15 puts the hopper under reduced pressure, with the result that air is drawn into the hopper 10 through the silica-gel dryer 22 and through it the porous stone 23. This air fiuidizes the abrasive in the hopper 10 with the result that some of it enters the orifice 13 and travels down the leg 18 into the air stream to the blast nozzle. The abrasive loosens debris from the surface being treated and this with the spent abrasive is sucked into the cyclone 26 where it falls onto a vibrating screen 28. The large particles of debris are caught by the screen. The smaller particles go with the abrasive into the hopper 10. Here, the upward moving air current through the porous member 23 fluidizes the abrasive-debris mixture, causing the debris to stratify into a layer below the orifice 13, simultaneously lifting the abrasive above it and causing the abrasive to flow easily down the leg 18 of the feed T 12. This fluidizing of the abrasive makes possible a metering feed of it to the blast gun and an effective cleaning of the abrasive as the continuous blasting goes on.

In brief what happens is that the dry abrasive powder is fluidized so it can be metered to the feed T 12, while the debris brought back from the work with the spent abrasive is settled out in the area below the orifice 13.

The area of the stone 23 and its porosity will be chosen with the size of the abrasive and the size of the blast gun in mind. The same is true of the size of the feed orifice 13. The height of the orifice 13 above the stone 23 will be regulated by the length of runs between shutdowns to clean out the debris. The porosity of the air pervious member 23 can be selected on the basis of the upward air flow needed to produce the desired aeration of the abrasive and the settling out of the debris.

While I have mentioned the use of air pervious stone for the part 23, it is possible to use other air pervious materials which will have an equivalent operation in the device.

The tube 18 may be made adjustable in height in the bottom of the hopper 10 by any well known expedient,

such as by the use of a slip joint sealed by an O ring or the like.

What I claim is:

1. In a dry honing device for treating the surface of materials with fine abrasive particles contained in an air stream, including a source of air under reduced pressure, a feed hopper for said abrasive particles, also connected to the aforesaid air source, a blast nozzle for directing said particles at said surface, the device for feeding said abrasive particles to said nozzle being characterized by a housing secured at the bottom of said hopper, an air inlet into said housing, an air pervious partition separating said housing from said hopper, said partition formed from a porous material having a large number of irregular tortuous passages, the porosity of said partition being chosen to give the desired air fiow from the air inlet up into the hopper, while preventing downward flow of the abrasive particles through the partition when no air is flowing, an outlet from the bottom of said hopper, connected at its lower end to the blast nozzle and terminating at its upper end in an orifice spaced above the air pervious partition, whereby the abrasive in said hopper will be fluidized to facilitate its flow into said outlet orifice, and during continuous operation of said device, the effect of the fiuidizing will be to cause particles of debris mixed with the abrasive to settle into the hopper area below said outlet orifice and to leave the abrasive above it substantially uncontaminated with particles of debris.

2. The device of claim 1 in which said partition is a porous stone.

3. An abrasive impelling device including a source of air under reduced pressure, a blast nozzle in the enclosed work area, a suction trap in the bottom of Said area, a cyclone connected to said trap, a hopper connected with and located beneath said cyclone, means connecting said source of air to said hopper and to said blast nozzle, wherein an airstream flows to said nozzle, an abrasive inlet tube in said means to introduce abrasive into said air stream, a housing area in the bottom of said hopper formed by an air pervious partition separating said hopper into an upper storage area and said housing area, an air inlet into said housing area to admit air at atmospheric pressure which will flow upwardly through said partition, said abrasive inlet tube having its inlet orifice spaced above said partition, said partition having a large number of tortuous passageways whereby in continuous operation of said device, the air flowing upwardly through said partition will both fiuidize said abrasive and will cause any debris returned from said work area to settle onto said partition below the level of said inlet orifice so it will not be fed back to said blast nozzle.

4. The device as described in claim 3 including a screen member between said cyclone and said hopper to arrest large particles of debris removed by the blast nozzle in the enclosed work area.

Berg Jan. 26, 1954 Mead et al Nov. 20, 1956

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