US2998823A - Apparatus for cleaning surfaces - Google Patents

Description

Sept. 5, 1961 Filed May 15,

W. E. MCCOWN ETAL APPARATUS FOR CLEANING SURFACES 4 Sheets-Sheet 1 as 2 6 ae INVENTORS axmaL 27-W 720666 fdwope ATTORNEYS 4 Sheets-Sheet 2 I! I, I I, r I,

W. E. M COWN El AL APPARATUS FOR CLEANING SURFACES Sept. 5, 1961 Filed May 15, 1956 y ape Fla. 7

Sept. 5, 1961 w. E. MccowN m-AL 2,998,823

APPARATUS FOR CLEANING SURFACES Filed May 15, 1956 4 Sheets-Sheet 3 INVENTORS dammzd med. fii flzk A TTORNE YS p 1961 w. E. MccowN ETI'AL 2,998,823

APPARATUS FOR CLEANING SURFACES 4 Sheets-Sheet 4 Filed May 15, 1956 BY amzu. @66: 5215a! .e ATTORNEYS grinding and polishing operations.

I United States Patent 2,998,823 APPARA TUS FOR CLEANING SURFACES William E. McCowu and James W. McAuley, Toledo, Ohio, assignors to Libbey-Owens-Ford Glass Company, Toledo, Ohio, a corporation of Ohio Filed May 15, 1956, Ser. No. 585,087 6 Claims. (Cl. 134-46) The present invention relates broadly to washing or cleaning, and more particularly to an improved apparatus for washing sheets of glass and the like.

Although the invention is not restricted to the washing of any particular article, whether glass or other material, it is especially well adapted to carry out the difficult cleaning of glass sheets, particularly plate glass sheets which may have been imbedded in plaster during the preceding Heretofore, it has been dilficult to completely remove the plaster and other foreign matter deposited on the glass during these operations.

It is therefore an object of this invention to provide a novel apparatus for thoroughly cleaning glass sheets in a continuous manner, and one that is ideally suited for use i on a factory production line.

Broadly stated, the invention contemplates the washing of glass sheets in a more thorough and rapid manner than has heretofore been possible, by the use of sonic or ultrasonic vibrations.

The vibration frequencies used are generally over 100 cycles per second and preferably more than 10,000 cycles per second, and are transmitted in the form of mechanical vibration sound Waves through a suitable medium, for producing energy by means of which work'is performed. More particularly, as the sound waves are propagated through the medium, which is preferably a fluid, the motion of the particles of said medium is related to the characteristics of the sound waves. In this manner, the sound or ultrasonic waves will create cavitation in a liquid medium; cavitation being the effect of the alternate formation and collapse of gas bubbles or cavities. This collapse of the cavities creates an agitation of sufficient magnitude to actually disintegrate particles of substantially solid material; and it has been found that this vibratory agitation may be used to disintegrate particles of foreign matter from surfaces to be cleaned so that such particles may be easily and readily removed therefrom.

In its more specific aspects, the present invention employs the phenomenon just described to wash glass sheets by continuously passing such articles through a bath of a suitable liquid medium which is being vibrated by generating elements. These generating elements, which may be, for example, magnetostrictive transducers having a suitable output and frequency, are preferably arranged so as to direct the effect of said vibrations onto the glass sheet being moved therebeneath along a path substantially normal to the surfaces thereof and employing a reflector plate, positioned below the transducers and the glass sheet to reflect the vibrations to the underside of the sheet. In this maner, the effect of said vibrations is maintained at a maximum over all points of said surfaces.

By moving the glass sheets continuously between the generating elements and the reflector plates, there will be, in effect, a sweeping washing action across both surfaces. Under this procedure, washing proceeds rapidly, and movement of the sheets concurrent with the washing action'multiplies the speed of cleaning. Moreover, when the liquid medium, into which said sheets are submerged during washing contains a detergent, the particles of foreign matter that disintegrate upon the surfaces of the glass sheets may be even more quickly removed.

Patented Sept. 5, 1961 through a liquid medium during continuous movement of said sheets through said apparatus.

In the combining of vibratory devices such as ultrasonic transducers and conveying means, it is necessary to coordinate the two structures in order to provide a satis-' factory continuous washing device. Also where it is desired to use vibratory devices on only one side of the sheet material which is to be cleaned and means opposite the vibratory devices for effecting the desired cleaning on the other surface of the glass sheet, problems are encountered in coordinating these elements to provide a satisfactory machine. However, it is an important advantage to be able to clean both sides of a sheet of glass while the sheet is being moved, by means of vibratory devices positioned on only one side of the sheets.

Accordingly, a further object of this invention is to provide an improved apparatus within which the glass sheet can have both the surfaces washed simultaneously by means of vibratory devices on only one side of the sheet, and means for causing said vibrations to clean both sides during continuous movement of the said sheets. A still further object of this invention is to provide 'control means for protecting the vibratory devices from injury and from excessive use.

Further objects and advantages of the invention will become more apparent during the course of the following description when taken in connection with the accompanying drawings.

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

FIG. 1 is a side elevation, with some parts broken away, of one form of the apparatus embodying the invention and in which glass sheets are moved horizontally;

FIG. 2 is a transverse sectional view taken substantially on the line 2-2 of FIG. 1 showing the arrangement of one set of squeegee rolls in detail;

FIG. '3 is an isometric view taken substantially on the line 3-3 of FIG. 1 showing the sheet thickness gauge;

FIG. 4 is a schematic plan diagram of the transducer section of the apparatus showing the staggered arrangement of the packaged transducer assemblies;

FIG. 5 is a transverse section of the apparatus taken on the line 5-5 of FIG. 1 showing the arrangement of the transducers and the reflector plate;

FIG. 6 is a vertical section of the apparatus'shown in FIG. 5 taken substantially on the line 6-6 of FIG. 5;

FIG. 7 is a transverse section of the apparatus taken on the line 7-7 of FIG. 1 showing brushes for the final cleaning of the glass sheets; and

FIG. 8 is a diagram of an electric circuit used for controlling the electric current which supplies the vibratory devices of this invention.

Referring now to the drawings and in particular to FIG. 1, the sheets of glass 20 are advanced on rubber covered rolls 21 of a conveyor 22 forming the terminal portion of a production line for grinding and polishing sheet glass. The numeral 23 indicates the washer in general, which is comprised of the three principal sections arranged in the following order: the sheet thickness gauging section 24.

3 tends the length of the washer 23 and contains the cleaning liquid which is maintained at the level indicated by the numeral 38 (FIG. 6) so that the glass sheets are immersed as they pass through the washer. The shafts are received by bearings'39 mounted on the frame members 40 of the conveyor.

Referring to the thickness gauge section, shown particularly in FIGS. 1, 2 and 3, a rubber covered squeegee roll 41 is mounted on the shaft 35, replacing the conveyor roller 34, and a mating squeegee roll 42 is positioned directly above and in contact with roll 41 on a shaft 43. Both shafts extend through bearings 44 and an outboard bearing 45 and are rotated through sprocket 33 and gears 46 at the opposite ends of the shafts. The bearings 44 permit the rolls 41 and 42 to yield or spread as a sheet of glass enters between them and universal joints 47 have been inserted between the ends of shafts 35 and 43 and the gears 46 to compensate for the misalignment occasioned by said yielding of the rolls.

The thickness gauge proper is indicated by the numeral 48 and is comprised of an elevated platform 49 rising from each side frame member 40. The platforms rise above and extend inwardly over the trough 37 and are in transverse alignment with each other. A switch 50 is mo nted on top of each platform 49 with the actuator thereof extendinginwardly. Downstream from the platform 49, rocker arms 51 are attached by pivots 52 to bearing blocks 53 fastened to the top rim of the trough 37. One end of each of the rocker arms carries an extension 54 adapted to contact and operate the switch 50, the other end of each rocker arm has an outwardly directed block 55 carrying an adjusting screw 56 which contacts the top rim of the trough 37 to limit the travel of the arms 51 in one direction. A roll 57 spans the distance between the rocker arms 51 at a point adja cent the blocks 55 and is mounted for free rotation in bearings 58 at this point. The switches 50 are connected in series with themotors 29 and may be connected to interrupt the circuit to any line motors ahead of the gauging section 24, so if a sheet of glass that is warped or is too thick to pass through subsequent portions of the apparatus, such as the transducer section 25, arrives at the gauging station 24, the roll 57 will be raised thereby and will incline the rocker arms 51 to open one or both of the switches 50 to cut the power to the motors 29 and the transducers 63 as will be described hereinafter.

Referring to the transducer section 25 of the apparatus, shown particularly in FIGS. 1, 4, 5 and 6, the transducer assemblies 59 are arranged in two pairs of banks, each pair having a bank 60 and a bank 61, in which the packaged assemblies 59 are staggered to the right and to the left as shown in FIG. 4 to secure complete transverse coverage of the glass sheet 20. The transducer assemblies 59 are comprised of a flame or holder 62 to package six transducers 63 for easy installation into the supporting member 64 which extends transversely above the glass sheet 20 and is in turn supported on piers 28. A reflector plate 65 is positioned below the glass sheet 20 and extends transversely thereof in alignment with 'each bank of transducers 60 or 61 and is also supported by prers.

Each of the individual vibrating or energy transmitting units 63 include generating face portions 66, and these are preferably placed in a closely spaced relation with respect to the top surface of the sheets 20 with the faces 66 submerged in the cleaning liquid 38 and with the faces arranged parallel to the top surface of the sheets as they pass through this zone on conveyor 27. This arrangement is important in that energy released from the faces 66 will then travel a path which is substantially normal to the top surface of the sheet 20 and so strikes the sheet at right angles. Likewise, the reflector plate 65 is positioned directly below the transducers 63, in a closely spaced relation to the lower surface of the sheet surface of sheet 20. However, the energy waves are not strictly confined to cleaning a surface the exact size of the generating face 66. It has been found that, within limits, the waves tend to diverge slightly and yet will satisfactorily clean an area slightly larger than the face area 66. Thus, as may be seen in FIGS. 4, 5, and 6, the transmitting units may be spaced apart from each other as it is not essential that the generating surface areas 66 fully equal the area of the surface to be cleaned thereby. I

.The vibrating or energy transmitting face surfaces 66 may be formed from piezoelectric materials such as quartz or certain ceramic materials which when coupled with particular types of alternating voltages produce very high vibration frequencies. Another type vibration generator that may be used is a magnetostriction transducer consisting of a laminated core of an alloy of ferromagnetic material such as nickel, iron and cobalt, which expands and contracts under the influence of a magnetic field. A third type of vibrator, a generator of the mechanical type such as an air hammer or Hartmann whistle using air jets or water jets in the liquid medium to produce ultrasonic vibrations, may also be employed in the vibration unit. Consequently the apparatus of the invention is not limited to any one specific form of energy transmitter.

In use the generating surfaces 66 and the reflective surface 67 are respectively placed parallel to the top and bottom surfaces of the sheets and the generating surfaces 66 are energized by an alternating voltage causing extremely rapid vibrations to occur on the face surfaces 66. Since the vibrating faces 66 are in direct contact with the liquid medium 38, alternate positive and negative pressure fronts are created which travel from the faces 66 and are reflected from the surfaces 67 to the sheets along a path normal to the glass surfaces.

These variable pressure fronts cause a cavitation or bubble effect to take place in the medium 38 which in turn acts upon the molecules of grease, plaster, dirt, or other foreign material on the sheet by first compressing the molecules towards the sheet, and then pulling the molecules towards the vibration generating elements as the bubbles collapse and create a negative pressure area. In this manner, using a detergent medium as an example, as the molecules are subjected to negative pressures, they are spread from one another in minute degrees allowing the iiquid medium to seep into the interstices and form a wetting layer between the adjacent molecules. Ev'entually, the detergent action of the liquid medium between the molecules causes the molecules to separate from each other and from the sheet thus leaving the sheet free of foreign matter.

These alternate positive and negative pressure fronts may be set up from a minimum cycle of times per second on up, resulting in tremendous pressures on the molecular structure of the grease or dirt during a short interval of time. However, ultrasonic vibrations are deemed preferable both to avoid the nuisance of noise and because better cleaning is achieved with vibrations in excess of 10.000 cycles per second. Consequently, the detergent action of the liquid medium on the molecular structure of the deposit material acting in combination with the mechanical vibration causes the material to become suspended in the liquid in a matter of seconds.

Alternatively, other methods of disturbing the molecular structure on the sheets using similar type vibration generators may be practiced. If the foreign material is such that it is susceptible to crumbling or cracking under repeated fluctuations of pressure, the generators may be used in conjunction with a liquid medium having little if any detergent effect. The liquid medium in this case s,sas,sas

being used only to transmit thevariable pressure wave fronts. On the other hand, if the material to be cleaned can be dissolved by an acid in causing a chemical reaction to take place between the acid and the deposit matter, a medium of this type might also be used in conjunction with the vibration sources to remove the deposits on the sheets. 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 liquid containing certain types of abrasive material which cause an eroding action to take place on the foreign matter itself.

By using the arrangement herein described, glass sheets may be efliciently and efiectively cleaned on both sides by the use of banks of ultrasonic transducers located in juxtaposed position to only one side of the glass sheets. Such an arrangement allows the transducers to be placed on opposite sides of the glass sheets from the conveyor rolls so that the vibratory faces and the transducers can be adjusted at various distances of the glass sheets and placed in a number of positions without physical restriction by the conveyor rollers.

With the arrangement herein shown, it is seen that the reflector plates are located between the rollers of the conveyor so that the reflector plates do not interfere with the conveyor rolls and yet may extend across the entire length of the glass sheet and be adjusted in opposed position to the ultrasonic transducers. When the reflector plates are combined with the transducers, it has been found that the reflective surface 67 generally should be less than 0.10 inch from the glass surface being cleaned, and preferably the surface 67 should be approximately 0.06 inch. Such adjustment is achieved by adjusting the relative position of the reflective surface and the conveyor rollers between which the reflective surfaces are positioned. In operation, the glass sheets 20 are passed over the conveyor rollers 34 which fixes the position of the path of travel of the upper and lower surfaces of the sheet of glass. The ultrasonic transducers, the vibrating surfaces, and the cooperating reflective surfaces are adjusted in fixed position with respect to the conveyor rollers so that the vibrations to which the surfaces of the glass sheet are subjected are obtained from the vibrating and reflector surface in the optimum adjusted position. When the vibratory surface is vibrated by the transducers, ultrasonic waves are transmitted through the washing medium to the upper glass surface where cleaning is elfected and also downwardly to the reflecting surface which causes vibrations to be transmitted back to the lower surface of the sheet of glass to provide cleaning of said surface.

Referring particularly to FIG. 6, a series of nozzles 68 are positioned on perforated pipes 69 above and on both sides of each transducer bank 60 and 61 to spray coolant over the transducers 63. The coolant may be water or any other liquid consistent with the cleansing liquid. Each of the transducer banks 60 and 61 is enclosed on all sides and on the top in a ventilated compartment 70 formed of insulating material. Electrical connections 71 for the transducer assemblies 59 are supported on a bridge 72 straddling a pair of the compartments 70 and the washer 23.

Referring again to FIG. 1, the rinse section 26 is lo cated downstream from the transducer section 25. Two sets of squeegee rolls 41 and 42 replace the initial or lead rolls 34 of the rinse section, followed by a further continuation of conveyor 27 in which the glass sheets 20 pass through a liquid rinse and over brushes 73, shown in detail in FIG. 7. At this point, additional rolls 74 are yieldably mounted above the conveyor rolls 34 to hold the glass sheet 20 against the brushes 73. The rinse section terminates a short distance thereafter moving the glass sheet 20 through the final liquid rinse and on to further processing.

. During the operation of the washing apparatus, periods of time arise when the washing of the glass sheets is interrupted due to the shutting E of the apparatus on operation of the thickness gauge or simply because gaps in the continuous chain of sheetsbeing fed through the apparatus occur. Whatever the reason for the interruption of washing might be, it is desirable to shut off the ultrasonic transducers when not needed for washing to preserve their useful life. The apparatus of this invention is provided with control means which achieve this result and which are considered to be an additional improvement of this washing apparatus over those of prior art.

Referring to FIG. 8, there is shown a control circuit for preventing undue operation of the transducer, in which the normally closed switches 50 are connected in the circuit in series. However, if either of these switches are opened by the passage of a warped or thick sheet of glass 20 as such sheet passes through the thickness gauge, power to the motors 29 and to the transducers 63 will be interrupted.

In order to shut ofi the transducers when no glass sheet is passing thereunder, normally open switches 74 and 75 are respectively positioned at the entrance and exit areas of the transducer section 25 and are positioned to be closed by a sheet of glass 20 passing therethrough. The switches 74 and 75 are wired into the circuit in parallel so that closing of either or both of the switches will energize a relay 76 to supply current to the transducers 63. Thus it will be seen that the transducers 63 are only operating when a sheet of glass 20 closes either of the switches 74 or 75, thereby prolonging the useful life of the transducers.

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

We claim:

1. An apparatus for washing sheet glass comprising, a washing container for holding a washing liquid, conveyor means for conveying the sheet glass through the liquid, said conveyor means having supporting elements on which the glass is conveyed, vibrating means having vibrating surfaces disposed above and parallel to the path of travel of the glass being washed so as to impinge vibrations substantially normally onto said sheet,.

and a reflector shield disposed opposite said vibrating surface and positioned such that the sheet is conveyed between the shield and the vibrating surface and spaced from each, said shield being less than 0.10 inch from the surfaceof the glass being conveyed and disposed between the supporting elements of the conveyor means.

2. An apparatus for washing glass sheets, comprising a container for holding a washing liquid, conveyor means for conveying the sheets horizontally through the container and liquid, said conveyor means including spaced rollers for supporting the sheets being conveyed, a magnetostrictive transducer located without said liquid having a vibrating face disposed within said liquid above and substantially parallel to the path of travel of the sheets being washed to subject said sheets to vibrations substantially normal thereto, and a reflector shield disposed in opposed relation to the surface of said vibrating face positioned such that the sheets are conveyed between the vibrating face and the shield and spaced from. both, said shield being disposed betweentwo of the sheet supporting and conveying rollers and maintained at a distance of less than 0.10 inch from the bottom surfaces of the sheets.

3. An apparatus for washing glass sheets comprising a washing container for holding a washing liquid, conveyor means for conveying the sheets horizontally through the container and liquid, said conveyor means including spaced rollers forsupporting the sheets being conveyed, a magnetostrictive transducer located without 7 said liquid having a vibrating face disposed within sai liquid above and substantially parallel to the path of travel of the sheets being washed to subject said sheets to vibrations substantially normal thereto, and a reflector shield disposed opposite the surface of said vibrating face positioned such that the sheets are conveyed between the vibrating face and the shield and spaced from both, said shield being disposed between two of the sheet supporting and conveying rollers and maintained at a distance of approximately .060 inch from the bottom surfaces of the sheets.

4. An apparatus for washing glass sheet material comprising, a washing container for holding a washing liquid, conveyor means for conveying the sheet material through the container and liquid, vibrating means having vibrating surfaces disposed within said liquid in juxtaposed position to the path of travel of the sheet material being washed to subject said sheet to vibrations impinging substantially normally thereon, a reflector shield disposed opposite said vibrating surfaces and positioned such that the sheet is conveyed between the vibrating surface and the shield and spaced from each, and control means for preventing glass sheet material of excessive thickness from entering the cleaning area.

5. An apparatus for washing glass sheets comprising,

a washing container for holding a washing liquid, conveyor means for conveying said sheets through the material, said conveyor means having supporting elements on which the sheets are conveyed, vibrating means having vibrating surfaces within said liquid disposed above and parallel to the path of travel of the sheet being washed to subject said sheet to substantially normally impinging vibrations, a reflector shield disposed opposite said vibrating surfaces and spaced from each and positioned such that the sheets are conveyed between the shield and the vibrating surfaces, said shield being less than 0.10 inch from the surface of the sheet being conveyed and dis- '8 posed between the supporting elements of the conveyor means, and control means for preventing sheets of excessive thickness from entering the cleaning area.

6. Apparatus for simultaneously cleaning both sides of glass sheet material, comprising a tank for holding a supply of a liquid vibratory energy conducting medium, a conveyor for carrying said glass sheet material along a horizontal path through said tank and said liquid, a high frequency vibration generating means located above said liquid having vibrating faces disposed within said liquid in a slightly spaced parallel relation to the upper surface of said sheet material, a reflecting plate disposed in a parallel relation to saidvibrating surfaces located below said glass sheet material and slightly spaced from the lower surface of said sheet material, means electrically connected to said vibration generating means for energizing said generating means when said glass sheet material moves into opposed relation tosaid vibrating surfaces and for deenergizing said generating means when said glass sheet material moves out of opposed relation with said vibrating surfaces, and means responsive to the thickness of said glass sheet material for deenergizing said vibration generating means on seming excessively thick sheet material.

References Cited in the file of this patent UNITED STATES PATENTS Germany Ian. 21, 1954 7 line 34 UNITED STATES PATENT. OFFICE CTIFICATE oF CORRECTION Patent No. 2- 998 823 William McCown e11; ale

It is hereby certified that error appears in the above numbered patent requiring correction and that the sai d Letters Patent should read as corrected below.

Column 7 line 21, aft-er sheefi insert. material 11 strike out and spaced from each" and insert. the same after surfaces in line 36 same column 7 Signed and sealed this 30th day of January 1962,

(SEAL) Attest:

ERNEST W. SWIDER DAVID L. LADD Attesting Officer Commissioner of Patents September 5, 1961

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