US3447272A - Method for wet abrasive blasting - Google Patents

Description

June 3, 1969 A H. EPPLER METHOD FOR WET ABRASIVE BLASTING Original Filed March 12, 1965 Sheet of 2 IN VENTOR. fier /we H PPA 5/? BY Q1 6024, firm/ ATTORNEY June 3, 1969 I H, PP R 3,447,272

METHOD FOR WET ABRASIVE BLASTING Original Filed Harsh 12, 1965 Sheet 2 of 2 He THUR H. 5. 91.512

M, m Maw? United States Patent 3,447,272 METHOD FOR WET ABRASIVE BLASTING Arthur H. Eppler, 2518 W. Wisconsin Ave., Milwaukee, Wis. 53233 Original application Mar. 12, 1965, Ser. No. 439,198, now Patent. No. 3,343,304, dated Sept. 26, 1967. Divided and this application May 17, 1967, Ser. No. 639,079

Int. Cl. B24b N00 US. Cl. 51-319 6 Claims ABSTRACT OF THE DISCLOSURE A tank separate from the sump of the blasting equipment contains a batch of slurry of abrasive which is maintained in suspension by high velocity circulation of the carrier liquid pending pneumatic pressure delivery to the blast nozzle, the entire contents of such tank being maintained under high pressure without pumping, the circulation including little back pressure notwithstanding flow through an apertured baflle.

Background of the invention The instant application is divided from my application 439,198, filed Mar. 12, 1965, now Patent No. 3,343,304 and disclosing in detail apparatus for wet abrasive blastmg.

A slurry of abrasive and liquid carrier is extremely destructive of pumps and other parts of the apparatus which may be exposed thereto. Accordingly, it has become customary to elevate the slurry to the blasting nozzle under relatively low pressure and to use an aspirating jet of air at the nozzle to accelerate the slurry for blasting the work. The slurry being very heavy, the degree of acceleration produced by air under any practicable pressure is inadequate. It is impracticable to supply the slurry to the nozzle under any substantial pump pressure because the pumps used for this purpose will be destroyed after a very brief period of usage.

Accordingly, the present invention contemplates the Withdrawal of slurry from a sump in the treatment chamber and the storage thereof in a pressure vessel wherein a batch of slurry initially accumulated at low pressure is subjected to a head of high air pressure and is circulated rapidly under circumstances which assure that the abrasive will be maintained in suspension. Since the operation is a batch operation in which the entire vessel is under pressure, the circulation does not involve any great head resistance. It can, therefore, be accomplished by a screw rather than a centrifugal or a positive pump.

One particular means for maintaining the abrasive in suspension has proved superior to any other. The screw withdraws the slurry from the bottom of the batch tank and discharges it at an elevated position therein. From the point of discharge from the screw, the slurry flows by gravity back toward the bottom of the vessel. Enroute, the slurry is required to pass through small openings in a conical bafiie above which a mass of slurry is maintained without great ebullition while below it there is a partial void produced by the withdrawal of slurry by means of the screw at a rate faster than the slurry can flow through the apertures in the conical baflle. This results in great agitation and, apparently, breaks up any tendency of the abrasive particles to agglomerate.

Authorities consulted with regard to the superior results achieved have theorized that there may be a certain amount of ionization of the particles resulting from their passage through the bafiles, this being possibly attributable in part to the alkalinity of the carrier liquid, and the other to prevent agglomeration. They further theorize ice that agglomerated particles have a built-in cushioning effect which minimizes the abrasive action on the work in relation to the total weight of abrasive used. In contrast, the total abrasive action of individual particles propelled against the work at like speeds will be much greater.

In any event, exhaustive tests have shown that the abrasive action on the work is superior when the particles are circulated through the bafiie and projected under head of air pressure to the nozzle, where a jet of air under slightly higher pressure completes by aspiration the desired acceleration of the particles projected against the work. Using similar apparatus under a similar head of pressure and similar nozzles, but without the particular bafile, produces markedly less successful abrasive action.

Because the slurry is pressurized and circulated in a batch, a preferred embodiment of the invention includes a plurality of batch vessels in which the slurry is pressurized, the arrangement being such that a vessel from which slurry has been used can be relieved of pressure and refilled while the adjoining vessel is in service. Electrical programming means is used in the preferred embodiment of the invention to correlate the treatment of the work with the filling, and pressurizing, and relief of pressure, of the respective vessels.

Brief summary of the invention In lieu of pumping slurry under high pressure to an abrasive blast nozzle, the slurry is delivered from a batch to such nozzle under superatmospheric fluid pressure. There are one or more batch storage tanks in which slurry is maintained under rapid circulation on a path which preferably requires passage through the aperture of a baflie.

Brief description of the drawings FIG. 1 is a diagrammatic view partially in side elevation but largely in section through treating apparatus and one of the batch storage and pressurizing vessels.

FIG. 2 is a detail view taken in section on the line 22 of FIG. 1.

FIG. 3 is a fragmentary view on a somewhat reduced scale showing a more highly developed system in which two vessels are used interchangeably, the treating chamber being fragmentarily illustrated in an embodiment differing from that of FIG. 1.

FIG. 4 is a fragmentary view in horizontal section through the treating chamber, diagrammatically illustrating in plan the work support and treatment nozzles.

Description 07 the preferred embodiment Referring to FIG. 1: The treatment chamber 6 is generally conventional, having work supporting bars at 8 upon which the workpiece 10 is mounted for wet abrasive blast treatment. The work is accessible to the operator through a sleeve 12 which may optionally be provided with a glove-like closure at its inner end into which the operator may put his hands while manipulating the work beneath the nozzle 14. The glove-like closure is not shown because it is conventional and its showing Would obscure the illustration of the work.

Beneath the work is a sump 16 in which the used slurry may accumulate as indicated at 18. A centrifugal pump 20 driven by motor 22 has an inlet 24 provided with screen 26 through which slurry may be withdrawn from the sump 16 and recirculated through the discharge pipe 28 and returned to the sump, the purpose of this circulation being to maintain in suspension the abrasive content of the slurry 18.

In the past, the branch discharge pipe 30 leading from the pump 20 would have extended directly to the slurry inlet 32 of nozzle 14 where it would be subjected to the aspirating effect of air supplied through the line 34 for blasting the workpiece 10. According to the present invention the branch pipe 30 does not lead directly to the nozzle but leads, subject to the control of valve 36, into the pressure vessel 38 where batches of slurry can be accumulated from pump 20 under low pressure. A pressure venting line 40 controlled by valve 42 leads from the vessel 38 back to the lower portion of the treatment chamber 6. When it is desired to fill the vessel 38, the interior is reduced substantially to atmospheric pressure by venting air through the line 40.

The pressure vessel 38 has something the shape of an inverted bottle, its lower wall 44 being conically tapered downwardly to a bottom 46 which is immediately beneath the circulating screw 48. A pipe 50 controlled by valve 52 may be used to drain the vessel 38 but, as illustrated, it is equipped with a pressure gauge 54.

The screw 48 is provided with a shaft 56 supported in bearings 58 and 60 at its upper end. The bearings are mounted in a housing 62 supported on the plates 64, 66 which rest on the upper end of the vessel 38. The plates 64 and 66 are both apertured, the latter having the smaller aperture to provide a shoulder at 68 upon which the flanged seal chamber 70 is mounted. This chamber has upper and lower annular seals 72, 74 which may conveniently be made of rubber or the like to embrace the shaft 56. The purpose of the seals is to exclude the abrasive material from the bearings 60 and 58 for shaft 56.

The interior of the chamber 70 contains clear water allowed to circulate by gravity between such chamber and the storage and heat radiating reservoir 76 with which the seal chamber 70 is connected by upper and lower pipes 78 and 80. A Water supply line 82 controlled by valve 84 allows makeup water to be added as needed. It also maintains the seal chamber under pressure which is at least substantially equal to the pressure in the vessel 38 so that there will be little or no tendency for the abrasive liquid to enter the seal chamber. On the contrary, the tendency is for the water to leak through the seals outwardly of the seal chamber.

The water in the storage reservoir 76 and the seal chamber may not only be subjected to the pressure of water from line 82 but is preferably subjected to air pressure through pipe 85. The pipe 85 connects to the air line 86 which, in practice, has been maintained at 90 lbs. pressure, it being understood that the figure is given by way of example and not by way of limitation. This is the same air line which, subject to the control of valve 88, supplies air through the pressure line 34 to the treating nozzle 14.

The motor 90 is connected by belt 92 with shaft 56 to rotate the screw 48 at high speed. A tubular casing 94 encloses the intermediate part of the screw. The casing is supported on the arms 96 from a sleeve 98 attached to the plate 66 at the top of the vessel 38. The arrangernent is such that slurry elevated by the screw is confined within the casing 94 until it is discharged from the screw at the upper end of the casing. See the arrows 100. A rotary slinger 102 on the shaft 56 intercepts any slurry which might otherwise be thrown into the sleeve 92. All such slurry engaged by the slinger 1702 on shaft 56 is thrown radially outwardly so that the portion of shaft 56 above the slinger 102 is substantially free of slurry.

A very important feature of the invention is the provision of the conical baffle 110 which is mounted on the tubular casing 94 in a position to intercept all slurry elevated in vessel 38 and tending to return by gravity to the bottom of the vessel for recirculation by the screw. The bafile 110 is provided with a very large number of small openings at 112. By way of example and not by way of limitation, it may be stated that the battle performs advantageously if the openings all have the approximate diameter of holes on A" centers.

With the vessel 38 filled with slurry to the approximate level from which the vent line 40 opens, the vessel 38 is subjected to air pressure through line 114, manually adjustable reducing valve 116, and shutoff valve 118. Assuming the air supply line 86 to be at 90 lbs. pressure, this pressure also being communicated through reservoir 76 to the seal chamber 70, it has been found expedient to set the reducing valve 116 for the delivery of air under lbs. pressure into the upper end of the vessel 38. It will be understood that all figures are given by Way of example and not by way of limitation.

With the slurry under the desired pressure in the vessel 38, the motor is started to drive the screw 48 at high speed sufiicient to withdraw slurry from below the bafiie at a rate in excess of the rate at which the slurry will fiow through the baffle apertures 112. This will result in a partial void below the battle into which the slurry is constantly being discharged through the apertures 112 with considerable turbulence. Although very turbulent, the mass of slurry immediately above the baflle will be relatively non-ebullient. Accordingly, it is from the area immediately above the bafile that slurry under pressure is withdrawn from vessel 38 through the supply pipe 120, subject to the solenoid valve 122 for delivery to the slurry inlet 32 of the treatment nozzle 14.

All of the slurry used in treatment accumulates in the sump 16 beneath the work 10. None is returned to the vessel 38 until the conclusion of the batch treatment, at which time the vessel is vented through pipe 40*. The pump 20 will not be effective to refill the vessel 38. If it has been permitted to continue in operation, the output thereof wil have circulated idly back to the sump through the branch line 28. Only after the vessel 38 has been vented is the valve 36 opened so that a major component of the output of pump 20 will then be delivered into the vessel 38 for a repetition of the batch operation.

The construction shown in FIGS. 3 and 4 is generally similar to that above described but continuous treatment is permitted by an arrangement 'in which two of the vessels 38 are located side by side as shown in FIG. 3 so that one can be charged while the other is in use.

N 0 claim is made herein to the special treating chamber shown at 7 wherein multiple workpieces 11 are mounted on studs 13, which project radially from the work supporting turret 15. A shaft 17 supports this turret for clockwise indexing movement in successive increments of 90 each (in the particular embodiment shown).

The chamber 7 is provided with a loading station A defined by partition walls 19 which converge toward shaft 17 and have flexible wiping blades 2-1 engaged by radial flanges 23 with which the turret 15 is provided. At station A the treated workpieces are removed in each dwell of turret 15 and workpieces to be treated are substituted on the studs 13.

In the first 90 indexing movement of turret 15, the workpiece or workpieces mounted on the stud or studs 13 will be moved to a treating station B in the path of a treatment nozzle or nozzles 25. A cross head 27 supports these from the ends of reciprocable rods 29 which operate in fixed bearings 31 to permit the nozzles 25 to move to and from the workpieces 11 presented thereto. A yoke 33 couples the supporting rods 29 to the ram 35 which is moved in and out of the ram cylinder 37.

It is not necessary to isolate treating station B from treating station C to which the workpieces 11 are advanced in the next 90 indexing movement of turret 15. Here a similar arrangement to that above described permits the ram- 39 to move the nozzle or nozzles 41 to and from the workpiece or workpieces 11 exposed thereto.

The rinsing station D has its own sump land is isolated from stations C and A by partitions 43 and 19 respectively, each being provided with a wiper blade 21 engaged by one of the flanges 23 on the turret. At station D the workpiece o-r workpieces 11 will be subjected to cleaning blasts from either or both of liquid and air nozzles 45 and 47. At station =D all slurry is removed from the workpieces passing therethrough, leaving successive workpieces completed and in readiness for removal and replacement at station A.

From the standpoint of method, it may be maintained that, in the preferred operation of the apparatus shown in FIG. 4, a steady blast is delivered against workpieces 11 at station B while a reciprocating blast is delivered against workpieces at station C by causing the nozzles 41 to reciprocate inwardly and outwardly with respect to the workpieces during treatment. Since the apparatus is not claimed, the details of mechanism for effecting nozzle movement are not shown.

Referring now to FIG. 3, the treatment chamber 7 is here shown in !a section which include sa nozzle 25 for projecting slurry against the workpiece 1-1, the objective being to clean, or remove scale from, or to polish, the bearing surface 49 in the interior thereof. Nozzle 25 is supplied with slurry under pressure from one or -an other of the vessels 38 through the pickup lines 120 of the individual vessels, each being provided with its own control valve 122. The slurry received through either valve passes through line 126 to a manifold 128 having as many outlets 130 as may be required to supply hoses 132 leading to the respective nozzles.

The valves 122 which regulate slurry delivery from the respective vessels 38; the valves 361 which regulate slurry delivery by the pump 20 from the sump 18 to the respective vessels 38; the valves 421 which control the venting of the respective vessels 38; the valves 117 which control the pressurizing of the respective vessels 38 from the air line 86; the valves 89 which control the admission of air to the header 91 which services the several nozzles; are all controlled electrically from a programming device or sequence timer 150 which is also correlated by the electrical connection indicated at 152 with the gear box 154 from which the indexing of turret shaft 17 is operated. The timer function is further regulated from upper and lower limit switches 156, 158 which desirably operate magnetically according to the position of the armature member 160 carried by float 162, the arrangement being duplicated in each of the vessels 38. In short, the programming system (not shown in detail here) is such as to provide complete interlock between the parts to the 2 end that the turret 15 cannot index if any of the nozzles 25, 41 or 45 is engaged within a workpiece such as that shown at 11. Neither can slurry be discharged from either of the vessels 38 unless that vessel has first been filled and pressurized. Neither can either of the valves 361 open to receive slurry from the sump unless the respective vessel 38 has been vented. It will be understood that instead of showing a complete circuit diagram for effecting the described interlock, the foregoing description is supplemented only by the diagrammatic showing at 166 of electrical wiring to the respective solenoid valves from the programming device or sequence timer 150.

In the use of the device pictured in FIGS. 3 and 4, a given vessel 38 will be vented and filled during the indexing of the turret 15. During this indexing movement, the full vessel 38 will be made ready for the use of the slurry therein, the screw 48 being set into motion and the contents of the vessel being pressurized. When, therefore, the indexing movement of the turret 15 has been completed by rotation of its shaft 17, one of the supply valves 122 will be opened to draw from immediately above the baffle 110 of the respective vessel a supply of slurry in which the abrasive is in suspension in a form which minimizes agglomeration of abrasive particles.

It should be noted that in the preferred practice of the invention the slurry contains a chemical additive in solution which changes the pH factor of slurry from 7 to approximately 10. It is believed possible that the ionization of the abrasive particles may be at least facilitated by alkalizing the carrier liquid.

The control of the operation by means of the respective floats 162 assures that the blasting operation will 6 be discontinued before one charge is exhausted, thu permitting a new charge to be continuously available for a substantially continuous functioning of the machine notwithstanding that each pneumatic projection of the slurry from a given vessel is a batch operation.

In order to disclose fully the best known means of practicing the invention, I herein disclose the following additional particulars. While related to the invention, these are given by way of example rather than by way of limitation, it being understood that I do not wish to limit my claims except as therein stated.

The invention may use any appropriate natural or manufactured metallic abrasive of such character that at least 50 percent of the abrasive used will last for a full 8-hour shift without disintegration into fines.

The preferred types of abrasives for the most efiicient use of the invention are the manufactured grits consisting of grains or powders of heat-treated aluminum oxide, silicon carbide, boron carbide, tungsten carbide, or oxides of cerium and zirconium. However, natural grits such as diamond, quartz, quartizite, tripoli, garnet, flint, jadeite, nephrite and others may also be used.

With reference to the desirable grain or particle sizes of the abrasives used, when I am using manufactured aluminum oxide abrasives, the predominant grain sizes have a broad range between 60 and 800 mesh according to the speed of cutting desired and the hardness and the shape of the surface to be cut, as well as the diameter of the orifice of the blasting gun and the distance at which the gun will be mainted from the work. With regard to natural quartz or other silicates or alumina, the preferred range of predominant grit size is between 60 and 140 mesh. The closer the proximity of the gun to the work, and the higher the specific gravity of the abrasive, the faster will be the cutting but it may be necessary, according to conventional practice, to make ajustments according to the toughness of the grit in resisting disintegration over a given period of reuse.

The amount of abrasive material to be kept in suspension is widely variable according to conditions. I prefer to use 30 to 50 pounds dry weight of abrasive in 70 to 50 pounds of aqueous vehicle, assuming that the grit does not exceed average grain size. When larger grit sizes are used, I prefer to incorporate only 30 pounds dry weight in at least 70 pounds of aqueous vehicle. If the specific gravity of the grit is reduced, I may, for the same grain size, use as much as 50 pounds of the lighter ma terial with each 50 pounds of the aqueous vehicle.

After the material has been recirculated many times for use over a period of eight to twelve hours of operation as much as 50 percent of dry weight of the same abrasive may be added to the slurry to recondition it for continued use. Preferably, however, the slurry is entirely changed and a completely new batch is used after one batch has been in repeated reuse for eight hours.

The preferred air pressure is maintained at about pounds p.s.i. at the source but I have success-fully used air pressure all the way from 125 pounds to 1250 pounds p.s.i. If the higher air pressures are used, it is, of course, necessary that the design of the equipment be such that the pressure can safely be handled. Desirably, the air is delivered to the blasting gun orifice from an air supply pipe which is engaged within the pipe which furnishes the slurry. However, I have also operated successfully with a gun in which the slurry delivery pipe is at the center and surrounded by the compressed air supply line. When multiple guns are supplied with pressure from a single source, the source must be maintained .at whatever predetermined minimum is required so that the concurrent operation of a number of guns does not draw down the pressure at the source. The carrier is normally ordinary water. However, I may use any other appropriate liquid carriers such as kerosene, methyl orange, varsol, light petroleum lubricating oils, and other low flash point solvents.

As already stated, it is preferred to use alkalizin agents in carrier to maintain the pH not lower than 7 and preferably as high as 10. Any appropriate proprietary chemical sold for alkalizing purposes can apparently be used. This is a factor which is most appropriate when the carrier is ordinary water.

An alkalizer sold under the trade name Metrolux has been used successfully at the rate of one-half ounce per gallon of water. This chemical is understood to comprise trisodium phosphate, sodium chromate and a form of lime which contains boron. Another proprietary chemical sold under the trade name No-Pac is used at the rate of four ounces for each twelve gallons of water. This chemical is understood to comprise lime which contains boron. In part, this acts as a rust inhibitor and, in part, it functions to maintain the aqueous carrier alkaline. Still another chemical sold under the trade name Cerfacto has been used at the rate of one ounce to each twelve gallons of water, where it functions as a non-ionic wetting agent to assist in maintaining the abrasive particles in suspension in the slurry and minimizes agglomeration. It is believed that this particular chemical also assists by keeping each abrasive particle isolated from other abrasive particles and entrained in a single droplet of water. Finally, I have successfully used .as an additive a Du Pont product sold under the trade name Duponol. This is employed at the rate of one teaspoonful to twelve gallons of water.

Referring now to the structure of the mechanism, the preferred thickness or gauge of the material used in the conical baffle is ten gauge, this being identical with the outer walls of the tank and the casing for the screw pump. The taper or angle of the conical baflle should be such as to assure the run off of the abrasives and the minimizing of agglomeration on the bafiie.

The number and dimensions of the apertures in such conical baffie will be related to the interior diameter of the screw pump running through such conical baffie and to the rpm. of such pump screw and to the inside diameter of such slurry agitating and pressurizing tank walls to which such conical baffle extends from the casing of such screw pump. The apertures should be such as to retard but not prevent the return of the slurry being recirculated to the sump below such screw pump. In the practice which I prefer, the number and dimensions of apertures in the baffle have been such that within two minutes after the start of operation of the screw pump, partial vacuum willhave been established in the sump area below the baffle. In practice, it has been found desirable to have the baffle apertures of uniform size. Apertures of /8 diameter on centers have been used successfully.

An interesting factor concerns the functioning of the bafile in reducing or eliminating an electrical static discharge which occurs in the absence of a bafile. In experimentation with the device before the baflie was added, it was found that an electrical charge would accumulate on the slurry vessel notwithstanding conventional grounding precautions in the electrical wiring to the electrically operated parts. After the baflie was added and the number and size of apertures adjusted to produce the results described above, it was found that only a mild charge of static would accumulate on the vessel when the pump was started but this was insuflicient to discharge or to cause injury and it became dissipated within a minute or two after the pump reached full operation.

Another interesting phenomenon concerns the temperature of the vessel in which the slurry is being recirculated. After the perforated conical baflie plate was incorporated, the temperature of the walls of the vessel below the baffie dropped well below room temperature. It did not drop sufiiciently far to frost. However, if the baflle is not used there is no observable drop of temperature in the lower portion of the walls of the slurry vessel.

As for nozzle orifice sizes and shapes, there is no specific preference as to size but it is preferred that the greater effectiveness is desired, it is preferred to achieve this by increasing the number of nozzles.

The slurry vessel may be of any size and capacity to meet any desired requirements. It may be portable or installed permanently.

The very superior results achieved in the use of the system appear to be dependent, first, upon the pressure with which the slurry is supplied to the nozzle and, sec-' ondly, upon the fact that the individual abrasive particles are separate rather than agglomerated, because of recirculation through the baffle. The resulting blast has been used to de-burr harder metals than can be handled with conventional dry or wet blasting. In addition, it has been used to bore holes into and through, as well as to cut into and through, hard metals, ceramics, plastics, stone, cement, and wood and to do many other works of this type which cannot be done with conventional dry or wet blasting. Also, the method and apparatus will perform more rapidly and at less expense any operations of which dry or wet blasting are capable.

I claim:

1. A method of wet abrasive blasting through a conventional blast nozzle having slurry and air inlets and an outlet for air pressure discharge of slurry, which method comprises pressurizing a batch of slurry, rapidly circulating slurry of said batch while it is subject to pressure, whereby to maintain the slurry in homogenous suspension, and supplementing air inlet pressure for discharge of slurry from the nozzle by delivering the homogenous slurry from said batch to the nozzle under the pressure to which the batch is subject.

2. A method according to claim 1 in which the pressure to which the batch is subject is at least approximately as great as the pressure of air at the air inlet to said nozzle.

3. A method of wet abrasive blasting involving the projection of a slurry of abrasive in suspension in a carrier liquid through a conventional blast nozzle having slurry and air inlets and a slurry outlet, said method comprising the delivery of air under pressure to the air inlet of the nozzle, storage of slurry in a batch, subjecting the batch of slurry to pressure suflicient to deliver slurry from the batch to the nozzle, maintaining the pressurized slurry in the batch in substantially uniform suspension, and discharging the pressurized slurry from the batch to the nozzle.

4. A method according to claim 3 in which the flow of slurry through the slurry outlet of the nozzle is accelerated by air admitted under pressure to the air inlet of the nozzle.

5. A method according to claim 4 in which the step of maintaining the slurry at uniform suspension includes the circulation of pressurized slurry in the batch, and homogenizing the circulating slurry by passing it through an apertured bafile in the course of its circulation.

6. A method according to claim 5 in which slurry is stored in a plurality of tanks and is circulated in each and is discharged from a successive tank to said nozzle upon exhaustion of slurry in a tank from which slurry was previously delivered to the nozzle.

References Cited UNITED STATES PATENTS 2,200,587 5/ 1940 Tirrell 51-8 2,380,738 7/ 1945 Eppler 518 2,569,952 10/1951 Ridley 5112 2,576,008 11/ 1951 Gladfelter et a1. 51-8 2,613,482 10/ 1952 Hamacher 518 2,667,015 1/1954 Berg 51-12 2,797,530 7/ 1957 Garver 51-8 LESTER M. SWINGLE, Primaly Examiner.

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