US2883310A - Surface cleaning apparatus and method - Google Patents

Description

April 21, 1959 J. w. MCAULEY ET AL SURFACE CLEANING APPARATUS AND METHOD 2 Sheets-Sheet 1 Filed July 1, 1954 INVENTORS @wau? $221 ATTORNEYS III-III vv amm April 21, 1959 'J. w. MCAULEY ET AL 2,883,310

SURFACE CLEANING APPARATUS AND METHOD Filed July 1, 1954 2 Sheets-Sheet 2 INVENTORS fid ZML F/aala 29m A TTORNE YS plaster from'the fiat tops of'metal the surfacing of plate also remove layer 'to receive subsequent blanks to be surfaced.

tables, the 'and heretofore-cleaning of the tables has been done by :rotary wire brushes which acted inconjunction with water *dium; cavitation being the ellect "tion and collapse of solid material; and tationcan be used to disintegrate partielesofforeign. mat- United States Patent SURFACE CLEANING APPARATUS AND METHOD Application'lulylg1954, Serial No.'440,774 11 Claims. (Cl..134-1) 'The present invention relates'broadly towashing or cleaning, and more particularly to an improved method and apparatus for cleaning surfaces by high frequency vibrations.

Although the invention is'not restricted to the cleaning of any particular article or type of surface, it is especially'well adapted to carryout'the difficult job of removing tables employed in glass and willbe'described in that connectionhere.

In'the regular commercial production of'plate glass,

"the unfinished glass "blanks are ordinarily bedded upon surfacing tables in a layer ofplaster of Paris-or the like 'which securely holds them in and-polishing thereof. After the 'glass'has been surfaced place during the grinding the blank is removed "from'the tables and it is necessaryto the old plasterbedding and to apply afresh Because of the good bond'between the plaster and the removal of the old plaster presents a problem under pressure to remove the'plaster by an abrading action upon the tables.

However, the abrading action-of area to be damp, dangerous and unsightly. Further deficiences also inherent insuch a cleaning procedure involve increased maintenance costs resulting from the necessity for frequently adjusting the brushes as they '-wear down, and the replacing selves.

It is therefore a primary object of this inventionto provide a method and device which will-clean fiat surfaced bodies in an expeditious and efficientmanner.

More the washing of and rapid maninvention contemplates to the characteristics of the sound waves. In this manner,'the sound waves will create cavitation in a liquid meof the alternate "forma- 'gas bubbles or cavities. lapse of the cavities creates an agitation of suflicient magnitude to actually disintegrate particles of substantially wehave found that thisvibratory agiter on the-surfaces to be may be easily and readily phenomenon just described,

description when taken in ,each of the openings cleaned so that such particles removed therefrom.

present invention employs the to clean and remove plaster from surfacing tables by continuously passing such tables 'In a specific aspect, the

beneath vibration generating elements while maintaining a supply of a suitable energy conducting medium between said elements and the surface of the tables.

It is therefore another object of the invention to providea means whereby a plurality of vibration generating elements may be mounted above the path of a conveying means so that the generating faces thereof will completely traverse the surface of the conveying means as it passes therebeneath.

Another object of the invention is to provide a means whereby a thin film of a liquid transmitting medium may be confined to a very small and localized area over the surface being cleaned.

Further objects and advantages of the invention will became more apparent during the course of the following connection with the accompanying drawings.

In the drawings, wherein like numerals are employed to designate like parts throughout the same:

Fig. 1 is a perspective view of one form of cleaning apparatus constructed in accordance with the invention;

Fig. 2 is a vertical section taken substantially on line 2-2 of Fig. 1;

Fig. 3 is a partial :side elevation of an adjustment means for the mounting of the vibration generating elements;

Fig. 4 is a sideview of a vibration generating element or transducer used in the cleaning apparatus of the inven- Fig. 5 is a partial plan view of the apparatus of Fig. 1; and

Fig. 6 is a partial plan view of a modified arrangement of the invention.

are secured upon the tops of the tables layer of plaster. This is done in Then after the glass has been surfaced by the grinding and polishing units and removed from the tables in the unloading each end of the 14 are vertical flange portions 17 which decross beam 12 adjacent the legs portions 16 and horizontal flange fine rectangular openings 18 therebetween at the end of the beam. Slidablymounted for vertical movement in 18 is an open frame type of clampmg bracket 19. Mounted within the clamping brackets 19 adjacent the opposite sides thereof are specially formed channels 20 and 21 having grooves 22 therein and bridging the tables the channel 20 is secured to one side of each of the brackets 19 by means of screws 23, and the channel 21 is slidably mounted along a finished slot 24 in the opposite side walls of the brackets, being held in an adjusted position by an adjustment screw 24'.

The transducers 11, which are preferably of a magnetostrictive type having a laminated core 25 and electrical coil windings 26 (Fig. 4), are supported by the channels 20 and 21 along nodal tabs 27 on the core 25, which tabs fit in the grooves 22 of the channels, as shown in Fig. 2. The nodal tabs 27 are located at a point of substantially zero vibration of the transducer vibratory system so that a minimum of vibration energy will be imparted to the supporting structure, thus allowing a maximum amount of vibration energy to be expended upon the surface being cleaned.

By virtue of the novel supporting means provided herein, the transducers 11 may be easily removed from the supporting beam 12 to be repaired, or to be transferred to another cleaning table by merely loosening the adjustment screw 24 so as to allow the channel 21 to slide in the slot 24 thus causing it to disengage one of the nodal tabs 27 on the transducer core 25. After the channel 20 has been withdrawn from contact with the transducer tabs 27 of any one of the transducers, it may be removed from the beam by disconnecting the transducer power lead 28 and its associated plug 29 from the power supply housing 30 mounted on the upper side of the supporting cross beam 12.

As will best be seen in Fig. 5, the transducers 11 are spaced from each other as at a and both the transducers and the support beam 12 are initially arranged at an angle to the path of movement (designated by the arrow x) of the tables 10. This spaced and angular arrangement not only allows the transducers to vibrate without interference from each other, but it also provides a means whereby the corner b of the transverse sides 31 of each of the transducers may overlap the corners c of the adjacent transducer, and thus cover the space a existing between the transducers. In this way, the tables will be subjected to vibration waves across their entire area. If such diagonal arrangement were notprovided for, the space a between the respective transducers which is necessary for proper vibratory action, would allow narrow strips on the surface of the tables or sheets thereon to go untouched resulting in an inadequately cleaned surface.

When all of the transducers 11 are properly supported along the channels 20 and 21, the whole bank of trans ducers may be vertically adjusted to place the transducer working surfaces or faces 32 at the desired height above the surface to be cleaned by means of opposed adjustment screws 33, held in place by lock nut34, and carried by the horizontal flange portions 17 of the cross beam 12. These adjustment screws engage the clamping brackets 19 and provide a means whereby the brackets may be raised or lowered in the slot 18 defined by the flanges 16 and 17, and thus cause the channels 20 and 21 to raise or lower the transducers 11 to place them in proper position with respect to the surface of the tables 10 or sheets carried thereby. The clamping brackets 19 are kept in aligned position with respect to the vertical flanges 16 by means of keys 35 mounted on the inside of the flange which engage key-ways 36 formed in the sides of the clamping brackets. Thus, when the brackets are moved upwardly and downwardly the keys 35 engage the ways 36 and allow the brackets and channels associated therewith to move only in a vertical direction.

In accordance with this phase of the invention, as noted hereinbefore, a supply of liquid energy transmitting medium is maintained between the working surfaces 32 of the transducers and the surface being cleaned so that a cavitation effect can be set up in the liquid medium which will cause the molecular structure of the foreign material on the surface to be disturbed. This energy transmitting medium may be supplied by means of pipes or conduits 37 (Fig. 2) mounted above the path of the tables and adjacent the lower working faces 32 of the transducers 11. More particularly, the liquid medium, designated by the numeral 38 (Fig. 2), is directed onto the surface of the tables 10 and beneath the said faces 32 by means of spray holes 39 provided along the length of the pipes or conduits 37. In this manner, it is possible to set up and maintain a film of fluid over a narrow area of the surface being cleaned. While this film or layer of energy conducting liquid is extremely thin and vertically unconfined, it nevertheless completely fills the space between the transducer working faces 32 and the table surface due, at least to someextent, to surface tension and capillary attraction. These effects act to maintain the energy conducting medium beneath the transducer faces at a level substantially higher than that of the unconfined film'of the liquid that flows away from the transducers onto the remaining portion of the table surface. It will therefore be evident that the liquid medium 38, although unconfined, may be maintained in a thin but effective layer over the necessary narrow width of surface being cleaned, thus eliminating the need for tanks or other confining means to contain the liquid in sufficient volume to cover the transducer generating faces. The advantages of a technique in which the energy transmitting liquid is spread in a thin unconfined layer over a narrow area of the surface being cleaned, over prior known ultrasonic cleaning applications requiring large volumes of energy conducting medium in cumbersome rc taining tanks to completely surround the transducer or the article being cleaned will be apparent.

In operation the distance between the transducer working faces 32 and the table or objects being cleaned can be varied by means of the adjustment described hereinbefore, and the distance provided therebetween related to the surface tension and capillary attraction characteristics of the energy transmitting liquid. For example, with liquids having the greater surface tension and capillary attraction characteristics the transducers can be maintained at a greater v distance from the surface being cleaned inasmuch as the surface tension will not be overcome as easily to permit the liquid to become separated from the working faces 32.

With the transducer position determined, the conducting medium 38 is deposited therebeneath upon and over a narrow width of the table 10 being cleaned where it will substantially fill the narrow space between the transducer generating faces 32 and the table surfaces and be maintained by the natural forces mentioned above. The transducers are then energized by an alternating voltage supplied to the coils 26 thereof causing extremely rapid vibrations to occur along the area of the working faces 32. Since the generating surfaces are in direct contact with the liquid medium 38, alternate positive and negative pressure fronts which travel directly from the vibrating surfaces or faces to the surface being cleaned along a path normal thereto are created. These variable pressure fronts cause a cavitation or bubble effect to take place in the medium which in turn acts upon the molecules of foreign material appearing on the surface being cleaned by first compressing the molecules toward the surface, and then pulling the molecules toward the vibration generating elements as the bubbles collapse and create a negative pressure area.

As the tables 10 move past the bank of transducers 11, the surfaces thereof are cleaned as they are swept by the cleaning action of the cavitation effect mentioned above. This movement of the tables 10 past the working faces 32 of the transducers also causes a slight build up of the energy conducting medium along the side of the transducers facing the uncleaned portion of the table because of the .damming effect of the transducers and the resistance to flow of the medium and adhering to the transducer in the restricted opening between the table surface and the said working faces. Such damming effect aids the surface tension and capillary attractioncharacteristics of the medium by providing an abundant supply of liquid medium in contact with the working'surfaces 32 at all times when the tables are moving therepast.

While an energy transmitting medium of water may be advantageously used in many cases, in others, it is desirable to use a detergent medium as a transmitting medium as noted above. Forexample, in using a detergent medium, when the molecules are subjected to negative pressures they are spread from one another in minute degrees allowing the liquid medium to seep into the interstices and form a wetting layer between the adjacent molecules. Eventually the detergent action of the liquid medium between the molecules causes the molecules to separate from each other and from the sheet thusleaving the sheet free of foreign matter. These alternate .positive and negative pressure fronts may be set up'from 100 to 30,000 times per second, resulting in tremendous pressures-on the molecular structure of the depositmaterial during a short interval of time. Consequently, the detergent action of the liquid medium on the molecular structure of the deposit material causes the material to become suspended in the liquid in a matter of seconds. In this connection, for many applications it is desirable to use'de-aerated energy transmitting mediums as such ble pressure wave fronts. On the other hand, if the material to be cleaned can be dissolved by an acid in cansing a chemical reaction to take place between the acid and the deposit matter, a medium of the type might also be used in conjunction with the vibration generators to remove the deposit on the said surfaces. Other types of mediums may also be employed to obtain the cleansing action regardless of their chemical nature e.g. kerosene, sodium silicate, as well as liquids containing certain types of abrasive material which cause an eroding action to take place on the foreign matter itself.

As pointed out above, the cleaning method of this in-. vention is based primarily on the action of cavitation.

Wehave also discovered that the effectiveness of the cleaning action, particularly in such difficult cleaning functions as the removal of plaster from grinding and polishing tables, is dependent on the magnitude of displacement at the working face of the transducer. In other words, we find that displacement magnitudes or amplitudes suitable for other purposes, and even for other cleaning operations, are insuflicient to effectively clean hardened plaster from metal surfaces.

To illustrate, trials with-the magnetostrictive transducer shown and describedhere-as one form of suitable vibration generator with which the invention can be practiced disclosed that when normal cleaning power of 50 'watts was applied to the transducer it failed to effectively remove plaster. It was our theory that this was due to the fact that eifectiveplaster removal is dependent on the degree of cavitation as determined by the amplitude of displacement at the working face of the transducer or, differently expressed, on a sufficiently high power density, expressed in watts per square inch, at the working face.

By way of confirmation, we found that when we multiplied the power input some sixteen times, applying 800 watts that the very effective and complete cleaning described above was obtained. However, it should be un- 6 derstood that the matter of applied power is probably not the controlling factor because it is expected that the advent of vibration generators of greater efficiency, which may be of the same or different types or constructions from the magnetostrictive type here indicated as the preferred form, sufficient displacement orpower density at the working face may be obtained with a much lower power input.

While the vibration generators 11 used topro'duce'the cavitation effectin a liquid medium may operate continuously without interruption, it has been found that they overheat and tend to'lose their efficiency when operated continuously for long periods of time. Tocompensate for this condition, thereis herein provided a coolor other suitable cooling mediums upon the transducers so as to provide a cooling effect therefor and thus allow the transducers to operate at peak efficiency. However, it isto be pointed out that other'types of cooling means may be employed such as cooling pipes which cool by heat absorption, or air jets, etc.

Should it be desired to move thecleaning assembly to another table line or location, the complete unit may be moved without moving the individual'transducers therefrom by releasing the bolts 15 attaching the beam to the standards 13 and lifting the supporting beam 12 along the boss 43 extendingalong the upper portion of thebeam by means of crane hooks or the like which may be inserted in holes 44 provided therein.

An alternate embodiment of the invention is shown in Fig. 6 which differs from the embodiment of Figs. lto 5 by providing two parallel rows of vibration generators or transducers 11. This arrangement may be used to clean surfaces which have'an unusually hard material thereon requiring a greater amount of energy to break down the molecular structure thereof. Also, thearrangement shown in this embodiment may be used when'it is desired to 'move the conveying'means or tables 10 at a greater speed. If desired, in this embodiment it is not necessary that the transducers 11 and support 12 be disposed at an angle to the path of movement of the tables 10 since the respective transducersmaybe staggered to overlap one another as shown in Fig. 6.

It will be apparent that while the cleaning'apparatus discl'osedherein has been described in connection with cleaning of plaster from moving tables that it may also be used 'to clean sheet material'such as steel plate or glass and that the transducers may be moved while the object being cleaned remains substantially stationary or moves relative thereto.

It is also 'to be understood that the form of the invention disclosed herein is tobe taken as the preferred embodiment thereof, and that various changes in the shape, size and arrangement of parts may be resorted to without departing from the spirit of the invention or the scope of the following claims.

We claim:

1. Apparatus for cleaning a moving'surface comprising, a support mounted abovethe path of said moving "surface, a plurality of vibration generating elements provrded with'working faces and mounted on said support in a position to provide vibrations substantially normal to the surface being'cleaned, and means for building up a layer of an energy transmitting liquid on a localized area of said surface that fills all of the space between the entire working faces said vibration generating elements and of said localized area as said surface moves past said vibration generating elements.

2. Apparatus for cleaning moving flat surfaced objects comprising means for moving said objects along a definite path, a plurality of vibration generating elements mounted above said path and in overlapping relationship transversely thereof, 'sald vibration generating'elements having vibrating surfaces substantially parallel to the plane of said path for providing vibrations substantially normal to the surface being cleaned and means for maintaining a layer of energy transmitting liquid between and in contact with said elements and said objects.

3. Apparatus for cleaning a moving flat surfaced objcct comprising, means for moving said object along a definite path, magneto-strictive transducers mounted above and diagonally of said path of said moving object, said magneto-strictive transducers having vibratory faces substantially in a common plane and relatively close to the surface being cleaned, and means for depositing an energy transmitting liquid on a localized area of said surface and filling all of the space between the entire vibratory faces of said transducers and said localized area as said object passes beneath said magneto-strictive transducers. j

4. Apparatus for cleaning plaster from a surface of a plate glass surfacing table comprising, a support mounted above said surfacing table, a vibration generating element carried by said-support for providing vibrations substantially normal to the surface being cleaned, means for depositing an energy transmitting liquid between said vibration generating elements and said surface, and means for adjusting the vibration generating elements relative to said table and sufiiciently close to said surface to provide a heavy concentration of energy at the surface being cleaned and close enough to retain a liquid between and in contact with said generating elements and said surface by capillary action.

5. Apparatus for cleaning plaster from a surface of a plate glass surfacing table as it moves along a definite path comprising, a support mounted above said surfacing table, a plurality of magneto-strictive transducers mounted on said support for providing vibrations substantially normal to the surface being cleaned, cooling means for said magneto-strictive transducers, means for adjustably moving said magneto-strictive transducers relative to said table and sufiiciently close to said surface to provide a heavy concentration of energy at the surface being cleaned and close enough to retain a liquid between and in contact with said magneto-strictive transducers and said surface by capillary action, and means for depositing an energy conducting liquid between said magneto-strictive transducers and said surface, said energy conducting liquid serving to transmit undamped elastic vibrations to said surface from said magneto-strictive transducers so as to disturbthe molecular structure of end and side portions at an angle to the path of movement of said moving object, and means adjacent said vibration generating elements for depositing an energy conducting liquid between and in contact with said vibration generating elements and said surface and which fills all of the space between the entire working face of. each of said elements and said surface in advance of the vibration generating elements.

7. A method of cleaning a surface of a body comprising the steps of moving the said body along a predetermined path, providing a thin film 'of an energy conducting medium in the form of a tie-aerated liquid having a detergent material dissolved therein on a localized area of said body, and conducting elastic vibrations to said surface through said film.

8. In a method of continuously cleaning the entire area of a surface as it moves along a definite path the steps of arranging a plurality of fixed position vibration generating elements with their Working surfaces in closely spaced face to face relation with the moving sur face to be cleaned and with certain of said elements positioned rearwardly of other of said elements to bridge the gap between adjacent elements, and maintaining a relatively thin film of an energy conducting liquid between and in contact with said elements and the surface to be cleaned.

9. In a method of cleaning plaster from a surface the steps of depositing an unconfined body of an energy conducting liquid on a localized area of said surface, and transmitting elastic vibrations to said energy conducting medium to produce a cavitation effect therein involving suflicient displacement to remove the plaster from the surface through said liquid.

10. Apparatus for treating surfaces comprising a support mounted adjacent said surfaces when in position to be treated, a plurality of vibration generating elements provided with working faces and mounted on said support in a position to provide vibrations substantially normal to the surfaces being treated, means for creating relative movement between said surfaces and said vibration generating elements, and means for maintaining an unconfined layer of an energy transmitting liquid on a localized area of said surfaces that fills all of the space between the entire working faces of each of said vibration generating elements and said localized area during said relative movement therebetween.

11. In a method of treating an area of a surface with a vibration generating element provided with a working face, the steps of creating relative movement between the area of said surface to be treated and the working face of said vibration generating element to cause one to pass the other in close substantially parallel face-toface relation, maintaining a thin unconfined layer of an energy conducting liquid between and in contact with said surface area and said working face when in such relation that fills all of the space between the entire working face of said vibration generating element and said surface area, and transmitting vibrations in a direction normal to said surface area from said working face to said thin unconfined layer to produce a cavitation effect during said relative movement.

References Cited in the file of this patent UNITED STATES PATENTS -2,460,919 Bodine Feb. 8, 1949 2,484,014 Peterson Oct. 11, 1949 2,651,148 Carwile Sept. 8, 1953 2,702,260 Massa Feb. 15, 1955 2,717,319 Bundy, Sept. 6, 1955 FOREIGN PATENTS 278,905 Switzerland Feb. 16, 1952 587,214 Great Britain Apr. 17, 1947 978,290 France Nov. 22, 1950 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent NO, 2,883,310 April 21, 1959 James W, McAuley et alfl It is hereby certified that error appears in the-printed specification of the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 4, line 75, before "adhering" strike out w and column 6, line; 69, after faces" insert of line 70, after and" strike out H fH I Signed and sealed this 18th day of August 1959.,

Attest:

ROBERT C. WATSON KARL AXLINE Commissioner of Patents Attesting Officer UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION April 21, 1959 Patent No, 2,883,310

James W, McAuley et all,

It is hereby certified that error appears in the-printed specification of the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

g" strike out and column 6,

Column 4, line '75, 'before adherin line 69, after "faces insert w of line 70, after and" strike out n fn Signed and sealed this 18th day of August 1959 (SEAL)- Attest:

KARL AXLINE Attesting Ofiicer ROBERT C. WATSON Commissioner of Patents

Claims (2)

1. APPARATUS FOR CLEANING A MOVING SURFACE COMPRISING, A SUPPORT MOUNTED ABOVE THE PATH OF SAID MOVING SURFACE, A PLURALITY OF VIBRATIONS SUBSTANTIALLY NORMAL VIDED WITH WORKING FACES AND MOUNTED ON SAID SUPPORT IN A POSITION TO PROVIDE VIBRATIONS SUBSTANTIALLY NORMAL TO THE SURFACE BEING CLEANED, AND MEANS FOR BUILDING UP TO THE SURFACE BEING CLEANED, AND MEANS FOR BUILDING UP A LAYER OF AN ENERGY TRANSMITTING LIQUID ON A LOCALIZED AREA OF SAID SURFACE THAT FILLS ALL OF THE SPACE BETWEEN THE ENTIRE WORKING FACES SAID VIBRATION GENERATING ELEMENTS AND OF SAID LOCALIZED AREA AS SAID SURFACE MOVES PAST SAID VIBRATION GENERATING ELEMENTS.

9. IN A METHOD OF CLEANING PLASTER FROM A SURFACE THE STEPS OF DEPOSITING AN UNCONFINED BODY OF AN ENERGY CONDUCTING LIQUID ON A LOCALIZED AREA OF SAID SURFACE, AND TRANSMITTING ELASTIC VIBRATIONS TO SAID ENERGY CONDUCTING MEDIUM TO PRODUCE A CAVITATION EFFECT THEREIN INVOLVING SUFFICIENT DISPLACEMENT TO REMOVE THE PLASTER FROM THE SURFACE THROUGH SAID LIQUID.

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