US2982524A

US2982524A - Ultrasonic cleaning equipment

Info

Publication number: US2982524A
Application number: US760987A
Authority: US
Inventors: Marshall R Bland
Original assignee: Purex Corp
Current assignee: Purex Corp
Priority date: 1958-09-15
Filing date: 1958-09-15
Publication date: 1961-05-02
Anticipated expiration: 1978-05-02

Description

May 2, 1961 M. R. BLAND uLTRAsoNIc CLEANING EQUIPMENT 5 Sheets-Sheet 1 Filed Sept. 15, 1958 IIIIIIIIIIIIIII l' JNVENToR. Mes/4MM JQ. 5MM/0 Arrow/EVS.

May 2, 1961 M. R. BLAND 2,982,524

ULTRASONIC CLEANING EQUIPMENT Filed Sept. l5, 1958 5 Sheets-Sheet 2 rraeA/ys May 2, 1961 M. R. BLAND ULTRAsoNIc CLEANING EQUIPMENT Filed sept. 15, 1958 3 Sheets-Sheet 5 i Unit thee Patented May 2, 1961 ULTRASONIC CLEANING EQUIPMEN Marshall R. Bland, La Habra, Calif., assigner, by rnesne assignments, to Purex Corporation, a corporation of California Filed Sept. 15, 1958, Ser. No. 760,987

17 Claims. (Cl.259-1) the high velocity rotation of specific shaped generators including a Wedge type sound generator by a .propeller in a body of liuid being displaced at high velocity toward and from a cleaning zone by the propeller so as to produce ultrasonic wave energy in the cleaning zone acting in cooperation with the liquid to remove soils from the parts.

Speaking generally with respect to the prior artV concerning ultrasonic cleaning, the applicators or transducers previously used for such cleaning and of which I am aware have been mounted so as to be non-movable during their operation to produce ultrasonic wave energy propagated into the coupling solution within which the parts to be cleaned are immersed for producing cavitation at the parts surfaces. Electro-mechanical transducers typically used for this purpose are necessarily rather complex and therefore are conned to a fixed position relative to the receptacle containing the cleaning liquid. However, such fixed positioning of transducersdoes not best promote the distribution of liquid cavitation over extended surfaces of parts to be cleaned, the parts normally 'being stacked in different random positions in a basket lowered into a cleaning zone within a liquid receptacle. `As aresuit, .certain surfaces ofthe parts closer to the transducer will receive ymore ultrasonic treatment than `other parts surfaces located remotely or at a greater distance from the transducer, and such differential treatment makes the degree and time of cleaning unpredictable. I `am aware that attempts have been made to overcome this problem through the use of many xed location.electro-mechanical transducers; however, such provision is extremely expensive and hence `prohibitive in low cost cleaning equipment.

The present invention seeks to avoid the difficulties mentioned above through the provision of a fluid dynamic wedgevtype sound generator bodily rotated in a moving body of cleaning liquid at a speed suflicient for the production of ultrasonic energy. Such rotation serves not only to effect production `of the desired ultrasonic Wave energy, but also to move the energy source in relation to the parts surfaces to be cleaned so that no parts surfaces remain located at fixed distances from the generator. As a result, more nearly uniform cleaning rates for all parts surfaces -are realized, with consequent decreased differential cleaning treatment of differently located parts surfaces. rotary means carrying it is simplevto manufacture, does not have orifices subject to clogging, and is capable of producing utrasonics at relatively low velocities in a liquid bath. Operation of the 'generator is characterized by relativeflowage of liquid pastanedge or edges of the wedge In addition, the wedge-type generator and the l being rotated through liquid at such high velocity and reduced pressure that ultrasonic waves are produced and propagate into the tank cleaning zone. Also, a broad spectrum of ultrasonic frequencies is produced for efficient cleaning treatment of many different objects coated with different soils, as distinguished from the rather narrowl spectrum of ultrasonic frequencies produced by electromechanical transducers.

Accordingly, it is a major object of the present invention to provide ultrasonic cleaning equipment broadly comprising rotary means axially rotatable in a body of liquid and wedge means carried by the rotary means for high velocity rotary displacement in the liquid in the direction of wedge taper relatively to accelerate liquid over y' the `wedge tapering surface or surfaces and producing u1- trasonic disturbances propagating in the liquid and acting to aid cleaning of parts inserted therein. More speciically, the invention contemplates rotation of the wedge means by an axial fiow propeller received Within a recess in the side wall of a cleaning receptacle and opposite a cleaning zone in the receptacle, so that ultrasonic disturbances propagate in liquid being displaced laterally into the cleaning Zone by the propeller to aid cleaning of parts in that zone, the recess walls acting to` guide thel liquid flo-w in most eflicient relation to the .propeller and parts cleaning zone and also to reflect ultrasonic wave energy toward the interior of the cleaning zone.

The wedge means referred to will typically include relatively forwardly tapering opposite sides at least one of which has forwardly and rearwardly spaced sharply defined edges over whichthe liquid relatively accelerates by a Bernoulli effect, causing the relative'ow velocity to increase and the pressure to sharply decrease at one and preferably opposite sides of the Wedge, and resulting in the formation at the sharp edges of the wedge of cavitation bubbles in the liquid. The formation and collapsing of these bubbles will in general produce vperiodic pressure changes propagating in the liquid :as waves of ultrasonic frequency. v

The invention furthermore Acontemplates mounting one or more Wedges either on a ring coaxial with and carried by a screw propeller or on the propeller blades themselves, the wedges being arranged both circularly and radially with respect to the propeller axis, and the wedges tapering in opposite directions of propeller rotation to facilitate sonic energy production during y'both forward and reversecycling of the propeller, as ywilll be described.

These and other objects and advantages of the invention. as well as the details of an illustrative embodiment, will be more fully understood from the following detailed description of the drawings, in which:

Fig. 1 is a side view of one form of the complete cleaning apparatus showing the receptacle partly broken away to show the interior construction thereof and the flow of liquid therein;

Fig. 2 is an end elevation of the exterior of the receptacle;

Fig. 3 is a view taken on `line 3-3 of Fig. l;

Fig. 4 is an enlarged frontal view of the propeller shown in yFigsl 1 and 3 and showing the sonic generators carried byV the propeller; i l l Fig. 5 is a view simzlar to Fig. 4 showing the manner in which the sonic generators may be mounted to the propeller blades themselves;

Fig, 6 is a view taken on line 6-6 of Fig. 4;

Fig. 7.is a perspective side view of the sonic generator shown in Fig. 6;

Fig. 8 is a section taken on line 8 8 of Fig. 5;

Fig. 9 is a cross-section through `a wedge-shaped propeller blade; and

Fig. 10 is a fragmentary showing of venturi tube type sonic generator of wedge design, carried by a propeller blade.

Referring first to Figs. l through 3, the cleansing apparatus includes an upright tank 11 which has opposite front and rear walls 12, and opposite side walls 13 together forming an interior zone 14 for receiving articles to be cleansed. Typically, such articles may comprise jet engine parts such as illustrated at 15 as retained in a rectangular basket 16 received downwardly between the receptacle Walls into the cleansing zone 14. The basket is shown as seated on a grating 17 typically having an egg-crate design and consisting of two sets of integral panels extending vertically and at right angles to one another to form spaces 18 therebetween into which soils removed from the parts 15 are adapted to settle out of the path o f liquid circulation in the receptacle.

The opposite walls 12 of th'e tank have recesses 19 formed therein which open transversely and divergently toward the cleansing zone 14. Each of the recesses is preferably in the form of a truncated pyramid having four divergent sides, a vertically spaced pair 20 of which diverge respectively toward the top and bottom of the receptacle. Similarly, a horizontally spaced pair 21 of the recess sides diverge respectively toward the opposite sides 13 of the receptacle, and it will be understood that as a result of this recess configuration the liquid is circulated in the tank in four loops which merge in the central regions of the cleaning zone, as indicated by the arrows in Figs. l and 3.

Such liquid circulation is preferably effected by a hydrodynamically designed and reversible thrust propeller 22, typically a three blade screw propeller, operable to displace the bulk of the liquid therethrough and alternately in axially opposite directions, as distinguished from the action of a centrifugal impeller which throws the bulk of the liquid radially therefrom during impeller rotation and moreover is not reversible to displace liquid in opposite directions as desired. Each propeller is attached to a horizontally extending shaft 23 projecting through the wall 12 at its flat square head or base 24 from which diverge the upwardly and downwardly flared wall portions 20 and the horizontally flared portions 21 of the receptacle wall 12. Attached to the base 24 is the housing 28 of an electric motor, which is preferably reversible so that the propeller 22 may be driven in opposite directions. Each of these motors may be of the induction type, so that by changing the polarity of the motor or the phase relationship of the applied current a reversal in the direction of the drive transmitted to the propeller may be secured. Current is applied to each motor through switching mechanism indicated at 30 which is operable to reverse the direction of drive transmission to the propellers from the motors, for purposes to be described. A master control switch is shown at 130.

In operation the liquid filling the tank is caused to be circulated by the opposed propellers, which have a common horizontal axis of rotation as shown in Fig. l, such circulation being indicated by the arrows. When the propellers are rotated so as to displace 4liquid axially therethrough, the liquid ows radially in a laminar or viscous flow pattern in each of the recesses 19 adjacent the

flared wall portions

20 and 21. Since those wall portions are outwardly to the top, bottom and opposite sides of the receptacle, the flow pattern therealong is streamlined and not turbulent. Furthermore, each propeller is spaced at a distance from the head or base 24 substantially equal to the diameter of the propeller, it having been found that this dimensional relationship is most desirable from the standpoint of the viscous or laminar ow pattern desired.

As the liquid leavesV the recess 19 in the four loops indicated by the arrows in Figs. l and 3, it circulates through the cleansing zone 14 in the symmetrical ow pattern shown by the arrows, which assumes that opthe tank or receptacle.

posite propellers are being rotated to displace liquid axially therethrough toward the heads or bases 24 and away from the cleansing zone. Such circulation is reversible by reversing the direction of propeller rotation to secure alternation of the impingement and shear effects of the flowing high velocity liquid upon the soils coating the parts to be cleaned. Also, opposite propellers may be rotated so that the liquid circulates completely across the tank from propeller to propeller. Under these conditions, the liquid passes through both propellers in the same direction, whereas -in Fig. 1 the liquid passes through opposite propellers in opposite directions.

Shown in the upper regions of Fig. 1 and also in Figs. 2 and 3 is a split cover or baie 32 extending in a horizontal plane and overlying the cleansing zone 14 within The cover halves are guided in tracks `33 so as to be slidable transversely outwardly away from the receptacle, leaving the cleaning zone exposed for downward reception of the parts basket 16. Fig. 2 shows a plate-type heating element 35 secured to the inner side of the receptacle flared wall portion 21 for heating the liquid therein to desired temperature for maximum cleaning efficiency, typical cleansing liquids consisting of trichloroethylene, cyclohexane, and solutions of detergents, or acids or bases, such as strong caustic soltuions. Representative soils to be removed from parts such as bearings, shafts, compressor blades, sleeves and the like include greases, oils, dust, tar, sludge, rust, resin, wax, carbon, lapping and buflingcompounds, and steel particles.

The tank shown in Figs. l to 3 has a sloping bottom tapering downwardly and away from the grating 17 to form a flow space 81 within which collected soils may flow laterally to the normally closed outlet 82. Liquid is typically supplied to the tank through an inlet 83 in wall 13 below the level of the cover 32.

Each of the propellers 22 is better shown in Fig. 4 as having three blades 40 together mounting a narrow ring 41 extending through slots 42 in the blade tips and welded to the blades to be integral therewith. Welded to the inner and outer sides of the ring 41 mid-way between each pair of blades are a radially spaced pair of sonic generators 47 each of which, as shown in Fig. 6, is endwise elongated in plate form and includes a rectangular body portion 48 and wedge shaped end portions 49 integral with opposite ends of the intermediate portion 48.

As each generator plate 47 is rotated in either endwise direction about the axis of the propeller shaft 23, its wedge apex edge 50 splits the liquid through which it passes as generally indicated by the arrows 51, the divided stream accelerating past the opposite tapering sides 52 of the wedge portion 49 and past the sharply defined rearward wedge edges 53. Such liquid acceleration leads to a Bernoulli effect, productive of split stream vibrations, cavitation bubbles and vortices shown at 54 streaming rearwardly at opposite sides of the plate 47 rearward of edges 53. Split stream vibration, and the formation and collapse of cavitation bubbles and vortices cause periodic pressure changes that propagate into the liquid as waves of ultrasonic frequency.

The same elects are produced at opposite sides of the wedge-shaped rearward portion of the plate 47, as indicated in Fig. 6, with production of split stream vibration, and formation and collapse of cavitation bubbles and vortices rearward of edges 53.

Referring back to Figs. 1 and 3, the ultrasonic energy generated by the rotating wedge generators emanates from the ring-shaped paths of generator rotation in the recessed zone 19 of propeller rotation, as indicated by the broken wave front lines 55 which travel laterally and substantially fill the mixing zone 14 of the receptacle with sound energy. The angularity of the recessed walls 25, 26, and 27 enables reflection of some incident ultrasonicwave energy back into the interior of the cleaning zone. Sound energy propagating into zone 14 acts in conjunction with the high velocity flow of the -randomly oriented parts surfaces, making the ultrasonic surface treatment of the parts more uniform, as brought out in the introduction. This effect is greatly enhanced by the use of opposite propellers each of which mounts sonic generators, as shown in Fig. l. Since the fluid dynamic generators create ultrasonic energy characterized by a broad frequency spectrum, there is negligible phase eect cancellation of energy waves travelling toward the center of the cleaning Zone from opposite recesses 19.

A modified form of mounting of the sonic generators 47 is shown in Figs. 5 and 8 wherein a single split diamond-shaped generator S7 is secured to opposite sides of the tip region of each propeller blade 40. In this form of the invention, the generator halves 58 are generall;l symmetrical and have sharply defined intermediate kedges S9` that are outwardly presented to the relative flow of liquid thereover, as indicated by arrows 60, so as to produce the same effects of split stream vibration, and cavitation bubble and vortex formation productive of ultrasonics as described previously.

The manner in which the

generator plates

47 and 57 are mounted to the propellers as viewed in Figs. 4 and 5 is an important feature of the invention; however, the invention broadly contemplates other methods of mounting sonic generator wedgeplates to rotary means such as propellers, all for the purposes previously described. For example, many wedge plates 57 can'be mounted on each propeller in radially spaced configuration. Also, the plates 47 can be mounted at their nodal vibration points 45 so as to vibrate and create ultrasonic energy, when rotated. lt will also be noted that by virtue of the fact that the

sonic generators

47 and 57 are tapered at their opposite ends, they will function to produce high intensity sonic energy during blade and propeller direction in either rotary direction, enabling sonic cleaning treatment of parts surfaces during the different tangential and normal force treatment of the parts surfaces by the high velocity liquid, as contemplated in the beginning portion of the specification. In all cases the wedge plates are carried by the rotary means at a radially outward location so that high intensity sonic energy will be produced in the liquid body.

Fig. 9 shows that the propeller blade itself may be wedge-shaped for creating ultrasonic wave energy, a cross section through such a blade being indicated at 70. In Fig. l a venturi tube 7l is carried at the top right receptacle `forming anvinterior zone for receiving a body of liquid and partsfto be cleaned thereinyrot'ary, means axially rotatable in the liquid received in thereceptacle and at one side of said zone, and means having blades for flowing liquid through said zone, and wedge v means carried' by said rotary means at a radially outward location relative thereto for high velocity rotary dis? placement in said liquid in the direction of wedge taper relatively to accelerate liquid over the wedge producing ultrasonic disturbances propagating in said liquid body through said zone as the Wedge is rotated in said liquid.

3. Ultrasonic cleaning equipment, comprising an upright receptacle forming an interior zone for receiving a body of liquid and parts to be cleaned therein, propeller means axially rotatable in the liquid received in the receptacle and at one side of said zone forcirculating liquid therethrough, and wedge means carried by said propeller means at a radially outward location relative thereto for high velocity rotary displacement in said liquid in the direction of wedge taper relatively to accelerate liquid over the wedge producing ultrasonic disturbances propagating in said liquid body through said zone-as the Wedge is rotated in the liquid.

4. Ultrasonic cleaning equipment, comprising an upright receptacle forming an interior zone for receiving a body of liquid and parts to be cleaned therein, said receptacle having a recess opening and divergently toward said zone, rotary means in said recess axially'rotatable in the liquid received in said receptacle for circulating liquid through said zone,l wedge'means carried by said rotary means at a `radially outward location relative thereto for high velocity forward rotary displacement in said liquid in the direction of wedge taper, said wedge means having a forwardly tapering side terminating rearwardly at a sharply defined edge, and means for rotating said rotary means at a speed such that liquid relatively accelerates over the wedge tapering side and sharp edge producing ultrasonic disturbances propagating in said liquid through said zone.

5. The invention as defined in claim 4 in which said rotary means comprises a propeller operable to draw of a propeller blade 72, the tube being wedge-shaped in cross section, as shown, for creating ultrasonic wave energy as the tube is rotated by the propeller in a body of liquid.

'Other uses to which the rotary wedge generators described above may be put include the generation of ultrasonic wave energy in liquids other than cleaning liquid, as for example solutions to be emulsilied by ultrasonic treatment.

I claim:

l. Ultrasonic cleaning equipment, comprising a receptacle forming an interior Zone for receiving a body of liquid and parts to be cleaned therein, rotary means axially rotatable in the liquid received in said receptacle for flowing the liquid therein, and wedge means carried by said rotary means at a radially outward location relative thereto for high velocity rotary displacement in said liquid in the direction of wedge taper relatively to accelerate liquid over the wedge producing ultrasonic disturbances propagating in said liquid body through said zone as the wedge is rotated in said liquid.

2. Ultrasonic cleaning equipment, comprising an upliquid in a first high velocity course of flow transversely from Within the interior of said zone toward said recess and to return liquid in a second high velocity course of flow transversely away from said recess and toward the interior of said zone.

6.V The invention as defined in claim 4 in which said wedge means has forwardly tapering opposite sides terminating rearwardly at sharply defined edges.

7. The invention as defined in claim 4 in which said last named means is operable to rotate said rotary means alternately in forward and rearward rotary directions, and in which said wedge means has forwardly and rearwardly tapering opposite sides terminating at sharply defined edges rearward of said forwardly tapering sides and forward of said rearwardly tapering sides.

8. The invention as defined in claim 7 in which said-iY wedge means comprises a forwardly and rearwardly elongated plate having a pair of .said sharp edges at each side of the plate.

9. The invention as dened in claim 8 in which said wedge means is diamond shaped and has a single sharp edge at each side thereof. l

l0. The invention as defined in claim 8 in which said wedge means comprises a plurality of wedge shaped plates spaced about the axis of said rotary means.

l1. The invention as defined in claim 5 in which said wedge means comprises a plurality of wedge-shaped plates carried on said propeller blades.

12. The invention as defined in claim 5 including a ring mounting said wedge means and carried by the propeller.

13. Ultrasonic cleaning equipment, comprising an upright receptacle forming an interior zone for receiving a' tacle having a recess opening and diverging toward said zone, rotary means in said recess axially rotatable in the liquid received in said receptacle for circulating liquid through said zone, said rotary means including a propeller operable to draw liquid in a rst high velocity course of ow transversely from within thel interior of said zone toward said recess and to return liquid in a second high velocity course of flow transversely away from said recess and toward the interior of said zone, said rotary means also including a ring extending about the propeller axis of rotation and secured to the outer portion of Ithe propeller blades, and wedge means mounted by said ring for high velocity forward rotary displacement in said liquid in the direction of wedge taper, said wedge means having a forwardly tapering side terminating rearwardly at a sharply dened edge, and means for rotating said rotary means at a speed such that liquid relatively accelerates over the wedge tapering side and sharp edge producing ultrasonic disturbances propagating said liquid through said zone.

14. Ultrasonic equipment, comprising means rotatable in a body of liquid, and wedge means carried by said rotatable means at a radially outward location relative thereto for high velocity rotary displacement in said liquid and for producing ultrasonic disturbances propagating in said liquid body as the wedge is rotated therein, said wedge means comprising a propeller blade having a diamond shaped cross section.

15. Ultrasonic cleaning equipment, comprising rotary means axially rotatable in a body of liquid, said means having blades for owing said liquid, and wedge means carried by said rotary means at a radially outward location relative thereto for high velocity rotary displacement in said liquid in the direction of wedge taper relatively to accelerate liquid thereover producing ultrasonic disturbances propagating in said liquid body as the Wedge is rotated therein, said wedge means comprising a venturi tube having a wedge shaped cross section, said tube being carried by one of said blades.

l6. Ultrasonic cleaning equipment, comprising an upright receptacle forming an interior zone for receiving a body of liquid and parts to be cleaned therein, said receptacle having recesses opening transversely and divergently toward opposite sides of said zone, rotary means in each recess axially rotatable in the liquid received in said receptacle and operable to draw liquid in a iirst high velocity course of ow transversely from within the interior of said zone toward said recess and to return liquid in a second high velocity course of flow transversely away from said recess and toward the interior of said zone, and wedge means carried by said rotary means at a radially outward location relative thereto for high velocity forward rotary displacement in said liquid in the direction of wedge taper, said wedge means including opposite forwardly tapering sides at least one of which has rearwardly and forwardly spaced sharply defined edges and means for rotating said rotary means at a speed such that liquid relatively accelerates over the wedge tapering side and rearward edge producing ultrasonic disturbances propagating in said liquid body.

17. The invention as defined in claim 16, in which said rotary means comprises a screw propeller.

References Cited in the le of this patent UNITED STATES PATENTS 982,578 Dilg Jan. 24, 1911 2,014,032 Sharpe Sept. 10, 1935 2,175,609 Leeb Oct. 10, 1939 2,495,159 Chertoff Jan. 17, 1950 2,516,656 Smith July 25, 1950 2,607,568 Seavey Aug. 19, 1952