US3099759A - Sonic treating apparatus - Google Patents

Description

30, J w MCAULEY SONIC TREATING APPARATUS 4 Sheets-Sheet 1 Original Filed March 18, 1957 M 4 lax/ 7 ATTORNEYS July 30, 1963 J. w. MCAULEY SONIC TREATING APPARATUS 4 Sheets-Sheet 2 Original Filed March 18, 1957 H WWW l IIIIHIIII nmmmfi iiiiiiiiiii INVENTOR. g'd/nwL WWP BY $656 ATTORNEYS July 30, 1963 J. w. MCAULEY SONIC TREATING APPARATUS 4 Sheets-Sheet f5 Omginal Filed March 18, 1957 INVENTm. BY gm; Wf @l/z? 2066c fi dwvpe ATTORNEYS July 30, 1963 J. w. M AuLE 3,099,759

SONIC TREATING APPARATUS Original Filed March 18, 1957 4 Sheets-Sheet 4 19 INVENTOR.

A TTORNE Y5 United States Patent Original application Mar. 18, 1957, Ser. No. 646,691. Divided and this application May 4, 1959, Ser. No.

Claims. (Cl. 31ll26) The present invention relates broadly to sonic vibration genera-ting apparatus, and more particularly to an improved form of surface treating apparatus that employs sonic vibrations.

This application is a division of application Serial No. 646,691, filed March '18, 1957, now abandoned.

Although the invention is by no means restricted thereto, it has been found to be especially well adapted to carry out the diflicult job of removing heat hardened plaster of Paris from the iiat tops of metal tables employed in the surfacing of plate glass and it will be described in that connection here.

During the conventional commercial production of ground and polished plate glass, unfinished plate glass blanks are normally secured to the tops of the grinding and polishing tables by bedding the blanks in a layer of plaster of Paris in order to hold them in place during the surfacing treatment. After the exposed surface of the glass has been ground and polished the blank is removed from the tables and it is then necessary to remove the old plaster and apply a fresh layer for receiving subsequent blanks.

Because of the extremely tight bond between the plaster of Paris and the tables after the plaster has set up and been subjected to the grinding and polishing heat, removal of the old plaster presents a serious problem in plate glass plants. Heretofore, cleaning of the tables has been accomplished by rotary wire brushes acting in conjunction w-ith water under pressure. However, the abrading action of the Wire damages the table tops and causes them to erode, thus requiring the tables to be more frequently resurfaces and replaced. Also the large amounts of water necessary to such a cleaning process makes the cleaning area damp, dangerous and unsightly; and the necessity of frequent adjustment of the brushes as they wear down, and replacement when they become too worn for effective use makes for increased maintenance costs.

Now, however, by means of the present invention, even this difiicult and unusual cleaning job can be carried out Without the deficiencies and objectionable features of the previous cleaning method by the use of sonic vibration, preferably in frequencies between 100 and 30,000 cycles per second, which are transmitted in the form of vibration sound waves through a suitable medium against the surface to be cleaned. As the sound waves are propagated through the medium, which is preferably a liquid for our purposes, motion of the particles of liquid is related to l the characteristics of the sound waves. That is, the sound waves will produce an alternate formation and collapse of gas bubbles or cavities, which phenomenon is referred to as cavitation. The collapsing of the bubbles or cavities creates an agitation within the medium of sulficient magnitude to disintegrate particles of substantially solid material which are in contact with the medium.

It has become general practice to produce high frequency sound energy by means of vibratory devices whose operation depends on the phenomenon of magnetostriction.

However, transducers of the magnetostrictive vibratory type heretofore used for cleaning purposes had a number of disadvantages. Among these were frequent short circuits in the energizing coils, eihciency reducing vibration 3,099,759 Patented July 30, 1963 "ice frequency shifts due to excessive heating of the transducers, broken mountings resulting from the sound vibrations, and transducer erosion caused by cavitation.

The apparatus of the present invention is designed to overcome these disadvantages and it is accordingly an important object of the invention to provide vibratory device with improved means for insulating the energizing coils.

Another object is to provide a cooling means for maintaining the operating temperature of the vibratory device below a predetermined maximum allowable value.

Still another object is to provide a mounting for the vibration generating device that is capable of withstanding the sound energy force.

A still further object is to provide a vibratory device in which portions contacting the energy transmitting medium are constructed of an easily replaceable erosion resistant material.

Still another object is the provision of a vibratory device including an improved laminated core.

Other 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 par-ts throughout the same:

FIG. 1 is a perspective view of a portion of a grinding and polishing line, showing a cleaning apparatus constructed in accordance with the invention incorporated therein;

FIG. 2 is a fragmentary perspective view on an enlarged scale, of a portion of the cleaning apparatus of FIG. 1, and showing two cleaning modules;

FIG. 3 is a longitudinal section taken substantially along the line 33 of FIG. 2;

FIG. 4 is an end view of one of the modules;

FIG. 5 is a fragmentary vertical, transverse, cross-sectional view taken along line 5-5 of FIG. 3,. and showing one of the transducers as positioned in the cleaning module;

FIG. 6 is a horizontal cross-sectional view of a transducer horn, taken along line 6-6 of FIG. 4;

FIG. 7 is a horizontal cross-sectional view of a transducer horn taken along line 7-7 of FIG. 4;

FIG. 8 is a fragmentary view of a portion of the transducer horn showing a wear plate attached;

FIG. 9 is a perspective view of an improved insulated energizing coil according to the invention;

FIG. 10 is a detail view partially in section of a moditfied form of transducer hor-n;

FIG. 11 is a perspective view of a module with a modified cover; and

FIG. 12 is an end view partially in section of two modules and a modified cooling means.

With more detailed reference now to the drawings, and particularly to FIG. 1, there is shown the plaster cleaning zone of a grinding and polishing line made up of a series of tables 10 for carrying glass sheets from a loading zone along an endless predetermined path, first beneath a series of grinding unit, then beneath a number of polishing units, to an unloading zone, and finally along a return section to the loading zone again.

As was stated above, the first step in surfacing glass sheets is to secune them to the tops of the tables 10 by bedding the sheets in a relatively thin layer of plaster. This is preferably done in the loading zone. After the upper faces of the glass sheets have been surfaced under the grinders and olishers and the sheets removed from the tables in the unloading zone it then becomes necessary to remove and clean the old hardened plaster 11 from the table tops before the tables may he used again for another surfacing operation. The plaster is usually -13 removed from the table in a table cleaning zone located between the unloading zone and the loading zone and as generally shown in FIG. 1.

The apparatus that is designed to remove the layer of old plaster according to this invention includes a plurality of transducers or vibration generating elements 12 including'a vibration source and amplifier or acoustical horn 1-3. These vibration generating elements are preferably-arranged in units or modules 14 mounted in a unique fashion, on a supporting means shown generally at 15, above and transversely of the surfacing tables iii.

In order to clean the table surfaces by sonic methods a layer of liquid or other suitable vibration transmitting material 16 is supplied and maintained between and in contact with the sheets to be cleaned and the working faces of the horns 13 from a nozzle .17. The purpose of this transmitting material is to provide a medium in which the sonic vibrations may produce cavitation which will agitate the medium sufliciently to loosen foreign particles from the surface of the tables and permit these particles to be easily removed. This loosening of the foreign particles and their subsequent removal provides the desired cleaning function.

In a preferred embodiment the transducers 12 are mounted in groups of six, which groups or modules 14 are of a unitary nature permitting their ready placement in operating position or removal and replacement in case of malfunctioning. These modules rest on horizontal angle irons 18 and 19, positioned above and transversely of the tables on support structures 20 at opposite sides of the line. The vertical height of the support means 15 is such as to provide a space between the surface to be cleaned and the work surface of the horns of .060 to .100 inch. As is shown in FIG. 1, a plurality of the modules are arranged in two lines with the modules in each line arranged in an abutting relationship and the two lines slightly staggered with respect to one another so that they will sweep the complete width of the tables 10 and not leave any unoleaned strips such as, for example, would be formed between two modules if only one line were used.

In order to overcome the high amount of heat that is produced by the transducers during their operation, cooling air under pressure is brought through a conduit 21, supply tubes 22, hoods 23 which fit tightly over the top of module covers 23', and then down over the transducers. The cooling air not only serves to increase the operating life of the transducers but also prevents unwanted frequency shifts which are brought about by excessively high temperatures in a transducer.

Each module is carried by a mounting bracket '24 comprising a pair of end plates 25 to which are affixed two longitudinal angle irons 26. These irons 26 are spaced parallel to one another and with enough space between them to permit the horns of the transducers to fit into this. space, while the length of these irons 26 is sufficient to accommodate six transducer widths. The upper surface of each of the irons 26 are provided with six equally spaced pin-like projections 27. These projections are received by the positioning slots 28 in the mounting flanges 29 of the transducers and are used for positioning the individual transducers in their proper relationship in a module as shown in FIG. 3.

When a module is being built up the individual transducers are placed onto the mounting irons 26 as shown in FIG. 3 with their horns extending downwardly through the space between the plates and the position slots 28 of the transducers engaged with the appropriate mounting pinsor projections 27. After the transducers have been so placed on irons 26 two securing bars 30 are then placed down over the mounting flanges 29 and are secured to the mounting irons by means of bolts 31 which when tightened maintain the transducers in a fixed contacting relationship with the mounting irons 26. These securing bars 30 replace the former method which was to bolt each of the transducers to the mounting irons 26. This older method was not satisfactory because the vibration of the transducers was sufiicient to break off the heads of the bolts and as a consequence necessitate repair or replacement. However, with the improved method of securing described herein six of the transducers are secured by means of two bars 30 which are themselves secured by four bolts of such size as to preclude their being broken during operation.

As seen best in RIG. 5, the transducers which generate the sonic energy used in the cleaning process in a U- shaped core or transducer stack 32 of very thin laminated nickel leaves or strips; a coil 33 arranged in surrounding relation to the legs of the U-shaped core and which when connected to an appropriate alternating power source will set up an alternating held within the core; a magnet 34 positioned between the legs 32' of the core and above the coil to provide a polarizing effect on the core; and an acoustical horn 13 which is secured firmly to the cross leg of the core for directing the vibratory energy produced by the magnetostrictive movement of the core to a region where this energy may be utilized.

Briefly, the principle of operation of the transducer is that an alternating field is set up in the core 32 when an alternating current is flowing in coil 33 which because of the ferromagnetic properties of the core produces a cyclic increase and decrease of the core length of twice the frequency of the voltage which is energizing the coil. Since the acoustical horn 13 which is firmly affixed to one end of the core moves with each cyclic changing length of the core the free end of the horn acts as a useful source of vibratory energy. The frequency of the voltage used is preferably 10 kilocycles although a number of satisfactory values may be found from cycles to 30 kilocycles depending on the type of cleaning operation performed, the amount of power used, and the design of the transducers.

As is shown particularly in FIGS. 3 and 4, the core 32 is constructed of a plurality of thin U-shaped strips of metal which are stacked together to form a unitary structure. These laminations are made of a ferromagnetic material such as nickel which are provided with an oxide coating to insulate them from one another to reduce heat produced by eddy currents. Heretofore, iaminations of approximately .010 of an inch thickness were used for such purpose, but it was found that by reducing this to around .007 of an inch eddy current losses can be reduced by 50% and notably better results obtained.

Heretofore the horns used in cleaning apparatus of the general type being discussed here required frequent replacement and it was determined that this was because the horns were so fashioned as to have recesses or conicavities exposed to the action of cavitation erosion. This invention utilizes a specially shaped energy directive member .13 (best shown in FIGS. 5, 6 and 7) which comprises an elongated hollow body of polygonal cross section including side walls 37 and an outer end wall 38 which enclose a cavity 35. This cavity as shown in FIGS. 5 and 7 has a circular cross section when viewed along the path that the sonic energy is to travel. When the cavity i viewed at right angles to the path of sonic transmission the lower portion as in :FIG. 5 shown slightly diverging walls as they are viewed moving away from the core piece 32, whereas the portion 36 closer to the core piece is an exponential curve. Thus, the cavity is constructed of a cone portion generated by revolving an exponential curve about a reference axis. Not only do the relatively smooth outer surfaces of the side walls 37 of the horn preclude severe erosion possibilities, but the use of the particularly shaped cavity within the horn provides an amplification of sonic energy. Therefore, because of this cavity sonic energy supplied at the upper end of the horn by the core will be amplified by the horn effect and present sonic energy of greater amplitude to the transmitting medium.

One satisfactory method of producing a born as described above is to cast it in two pieces and then weld the two pieces together into the final horn. It has been found that the configuration of the line of weld of the two pieces is very important in determining the ability of this weld to withstand deterioration by the sonic energy. For example, in the preferred embodiment a vertical weld a, that is one which is aligned with the direction of transmission of sonic energy, is found to be practically unaffected by the transmission of sonic energy therethrough. Whereas a line of weld which is substantially at right angles to the direction of transmission of the sonic energy is found to be very quickly weakened and destroyed.

The outer end wall 38' of the horn 13 is the portion which is placed in contact with the energy transmitting medium during a cleaning operation and is the portion which is subjected to the greatest amount of erosive wear by cavitation which wear at this point was a frequent cause of replacement of prior known transducers. The present invention overcomes this limitation by providing a wear-plate 39 (see FIG. 8) of hardened non-corrosive steel which is secured to the outer working face of the end wall 3 8 of the horn which is normally brought into contact with the energy transmitting medium. One satisfactory method of affixing this wear-plate to the transducer horn is by the use of an epoxy cement which is shown in FIG. 8 as a thin layer 40.

In FIG. 10 there is illustrated an acceptable form of weld configuration which also has been found to provide a satisfactory horn.

In order to overcome previously encountered difficulties with electrical short circuits between the different layers of wires in the energizing coil 33 and between the coils and the core 32 of the transducer these coils in the present invention have been impregnated with a highly insulative plastic material.

In fact, the coil assembly 41, as illustrated in FIG. 9, is completely embedded in a plastic body. This assembly consists of two sets of coils 33 each of which is wound in such a manner so as to encircle an elongated opening 42. When these coils are embedded in the plastic the openings are slightly wedge-shaped. The dimensions of the openings are suiiicient to enable them to accommodate six core pieces. Thus, when the transducers have been mounted in position in a module, 'as described hereinabove, the coil assembly is then lowered down onto the core pieces so that the openings 42 will receive the core pieces. When in final assembled position each of the coils 33 encircles one half of the legs of the core pieces. The magnets 34 are then placed in position between the core legs as is shown particularly in FIGS. 4 and 5 and held securely in place by retaining strip 34 attached to the inner surface of the module cover 23'.

Electrical power is applied to these coils through cable 43 which is of conventional structure. The plastic material protects the coil wires from the absorption of moisture and from the incurring of any damage to the coils when they are placed in position on the legs 32' of the core. This moisture-resistant feature is especially necessary when the transducers are cooled by water.

As was discussed previously herein the transducers produce a large amount of heat during operation and as a consequence of their elevated temperature they show a tendency to vary the frequency of the generated sonic energy. Therefore, as was also described herein, applicant has provided means for cooling the transducer by forced air means. A modified cooling means shown in FIGS. 11 and 12 is that of using water to reduce the temperature of the vibratory energy generating device. in order to be able to do this the outside case 44 of each module in this modification is constructed of a foraminous material which will permit the application of sprays or 6 streams 45 of cooling water to the transducers. These sprays may be supplied by any of a number of different conventional nozzles 46.

Although the present invention has been particularly described in connection with the removal of plaster from grinding and polishing tables, it has also been found to possess utility in the cleaning of sheet materials, such as fior example glass sheets.

We claim:

1. In sonic energy generating apparatus comprising a plurality of magnetostrictive transducers arranged in sidebyeside relation, each transducer including a core, polarizing means and a metallic acoustical directive member secured to the core and extending therefrom in substantial alignment with the major direction of magnetostrictive movement of the core, a member having high insulation properties provided with an elongated opening for removably receiving the cores of the transducers therein when said transducers are in said side-by-side arrangement, and an inductively wound coil of wire embedded in said member encircling the cores of the several transducers.

2. In sonic energy generating apparatus as claimed in claim 1, in which each core comprises spaced legs and in which said member is provided with spaced elongated openings for loosely receiving the spaced legs of the transducer cores therein.

3. In sonic energy generating apparatus as claimed in claim 1, in which said opening is tapered in the direction of the cores, wit-h the larger end of the opening being adjacent the directive member.

4. A magnetostrictive transducer for imparting vibratory energy to a transmitting medium, comprising a core formed of insulated nickel sheets of a thickness less than .007 of an inch, an inductively wound coil of wire encircling said core, a core polarizing means, and a metallic acoustical directive member fixedly secured to the core and extending therefrom in substantial alignment with the major direction of magnetostrictive movement of the core.

5. In vibratory energy generating apparatus comprising a sonic energy generating module composed of a plurality of magnetostrictive transducers provided with notched flanges, a supporting surface provided with a plurality of uniformly spaced positioning pins received in said notches to hold the transducers in uniformly spaced relation, and securing means engaging said flanges for fixedly maintaining the transducers in said spaced relation.

6. In vibratory energy generating apparatus of the type comprising a sonic energy generating module consisting of a plurality of transducers arranged side by side and each having a substantially Uashaped core, with the legs of the cores arranged in two lines substantially parallel to one another, a unitary coil assembly consisting of a pair of Wire coils, one coil encircling one line of legs of the several transducers and the other coil encircling the other line of legs, and a plastic member in which said unitary coil assembly is embedded and which is removably received on said cores.

7. -A magnetostrictive transducer for imparting vibratory energy to a transmitting medium, comprising a core of magnetostrictive material, an inductively wound coil of wire encircling said core, a core polarizing means, a metallic acoustical directive member secured and extending outwardly from said core in substantial alignment with the direction of major magnetostrictive movement of the core, a metal wear plate disposed over the outer end of said acoustical directive member, and a layer of an epoxy cement interposed between said wear plate and the outer end of said acoustical directive member and securing them to one another.

8. In vibratory energy generating apparatus of the type comprising a sonic energy generating module including a plurality of transducers arranged side-by-side and each having a substantially Usshaped core, with the legs of the cores of said transducers being arranged in two lines subsmamial-ly parallel to one another, 'and a unitary coi l assembly comprising a plastic member having a pair of spaced pamalllel elongated :slodzs for loosely receiving themthnoulgh fiche spaced lines of legs of the cores and a pair of coils embedded in said plastic member, one coil encircling one line of legs and the second ooil encircling the ofnher line of Legs.

9. In vibratory energy generating appanatus as claimed in claim 8, in which said elongated xslo t-s are tapered in the direction of nhe cores, with the larger end of each slot being adjacent (the inner ends of said cores.

l0. In vibratory energy generating apparatus as claimed 111011311118, including a polarized magnet received between the legs of each core for retaining the plastic member in position.

References Cited in the file of this patent UNITED STATES PATENTS 8 2,632,858 Ca'losi Mar. 24, 1953 2,651,148 Carwile Sept. 8, 1953 2,704,333 Oalo'si et a1 Mar. 15, 1955 2,717,319 Bandy Sept. 6, 1955 2,745,084 Bundy May 8, 1956 2,748,298 Calosi et a1 May 29', 1956 2,784,119 McCrown et a1. Mar. 5, 1957 2,883,310 McAuley Apr. 21, 1959 2,930,913 Camp et Ial Mar. 29, 1960 2,946,981 'ONeflll July 26, 1960 2,964,837 Harris Dec. 20, 1960 FOREIGN PATENTS 844,160 France Mar. 23, 1938 OTHER REFERENCES Electrical Engineers Handbook, Fender-Del Mar, 4th edition, Electric Power, pages 3-22, see. 24.

Claims (1)

1. IN SONIC ENERGY GENERATING APPARATUS COMPRISING A PLURALITY OF MAGNETOSTRICTIVE TRANSDUCERS ARRANGED IN SIDEBY-SIDE RELATION, EACH TRANSDUCER INCLUDING A CORE, POLARIZING MEANS AND A METALLIC ACOSTICAL DIRECTIVE MEMBER SECURED TO THE CORE AND EXTENDING THEREFROM IN SUBSTANTIAL ALIGNMENT WITH THE MAJOR DIRECTION OF MAGNETOSTRICTIVE MOVEMENT OF THE CORE, A MEMBER HAVING HIGH INSULATION

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