US3766630A - Method for repairing old sonar transducers - Google Patents

Abstract

The method of using a stiff non-melting silicone lubricant; namely, Di-Methyl Polysiloxane oil and Silicone Oxide (SiO2) compound to repair and seal sonar transducers. The method of repairing the old transducers comprises the steps of using a chisel shaped hot iron to remove the rubber facing of the transducer resonator, filling the cavity with a non-melting silicone lubricant, specifically Di-Methyl Polysiloxane oil and Silicone Oxide (SiO2) compounds, then encasing the transducer with an exterior boot.

Description

United States Patent [1 1 Norfleet et al.

[ Oct. 23, 1973 METHOD FOR REPAIRING OLD SONAR TRANSDUCERS Inventors: William V. Norileet, 2313 Main St., Napa; Wilmer Charles Sibbach, 925 N. Camino Alta, Vallejo; Donald R. Schueler, 3064 Linda Vista, Napa, all of Calif.

Filed: Oct. 8, 1970 Appl. N0.: 79,151

U.S. Cl 29/401, 29/594, 340/8 LF Int. Cl B22d 19/10, B23p 7/00 Field of Search 29/401, 594;

References Cited UNITED STATES PATENTS 4/1948 Mason 340/8LF 10/1951 Kroft et al 340/8 LF STEPS STRIP ELEMENT FACE PLATE 1 WITH CHISEL CLEAN EXPOSED II RADIATING SURFACE WITH WIRE BRUSH MANUAL APPLICATION OFCOMPOUND 111 TO TRANSDUCER FACE INSTALL N DRY BOOT APPLY VACUUM OF Y .27" FOR 24 HRS. TO. sEcuRE BOOT PLACE BANDS ON TOP AND BOTTOM OF BOOT A REDUCE VAC ('--'6in) m1 TO OPERATIONAL LEVEL OF TRANSDUCER 2,613,261 10/1952 Massa 340/10 2,977,573 3/l96l Mott 3,281,769 10/1966 Hueter 340/10 X Primary Examiner-John F. Campbell Assistant ExaminerDonald C. Reiley, lll AttorneyR. S. Sciascia and Charles D. B. Curry [57] ABSTRACT The method of using a stiff non-melting silicone lubricant; namely, Di-Methyl Polysiloxane oil and Silicone Oxide (SiO2) compound to repair and seal sonar transducers. The method of repairing the old transducers comprises the steps of using a chisel shaped hot iron to remove the rubber facing of the transducer resonator, filling the cavity with a non-melting silicone lubricant, specifically Di-Methyl Polysiloxane oil and Silicone Oxide (SiO2) compounds, then encasing the transducer with an exterior boot.

5 Claims, 5 Drawing Figures APPLY INSTALL COMPOUND BOOT WET in TO BOOT PATENIE0ucI23|97a 3.766330 SHEET 1UF 2 INVENTORS WILLIAM V. NORFLEET WILMER C. SIBBACH DONALD R. SCHUELER w wa /4 ATTORNEY- PATENTEB BT2 97 3.766.630

-sum 2 0 2STEPS 9 SF' EE sTR|P ELEMENT mwE- I AC PLATE WITH ii 2n CHISEL r/,'

:/-;2; l2 T TfT/T/P ,1

. ??fl CLEAN EXPOSED /w B 11 RADIATING SURFACE kw WITH WIRE BRUSH z? MANUAL APPLICATION 1 OF COMPOUND m w o TRANSDUCER FACE y FIG 3 E A INSTALL DZ DRY BOOT Nb APPLY gggq-COMPOUND 111 TO BOOT APPLY VACUUM OF Y 27-" FOR 24 HRS. o SECURE BOOT P AcE BANDS ON It A TOP AND BOTTOM OF BOOT F IG 4 REDUCE VAC ('-=-'6in) INVENTORS ATTORNEY BACKGROUND OF THE INVENTION The present invention relates generally to the use of a stiff non-melting silicone lubricant with high energy transfer coupling characteristics as an energy transfer coupling and more particularly to a new method of using'a specificsilicone lubricant; specifically, a Di- Methyl Polysiloxane oil and Silicone Oxide (SiO2) compound sold under the trade-name Dow Corning l l 1 Compound (DC-1 1 1); as a repair material and seal for sonar transducers. i

Prior methods employed the use of castor oil as an energy transfer coupling, and a seal for retaining the castor oil. Castor oil being highly hygroscopic in nature, absorbs moisture from the atmosphere during application, so that when the repaired transducer is placed on line, and driven at high levels of power, a mismatch would develop between the rubber boot and the transducer. This mismatch causes cavitation in the rubber faces; with a subsequent reduction of power, and efficiency in the transducer. It has been found that cavitation creates most of the problems which eventually cause complete transducer failure or at least a reduction in efficiency to an unsatisfactory level. In addition to being hygroscopic, castor oil has a high viscosity and thus does not remain in the area of application, so that a special retainer means was required. Additionally, castor oil will leak into transducer interiors, penetrate wiring harnesses, and eventually reduce the overall resistance to ground in the transducer. Moreover, when the castor oil seeps into the bottom of the transducer, the seepage creates additional dry areas between the element faces and the rubber boot, causing somewhat irregular power output patterns. Finally, in the old process, the cavitated and oil soaked elements had to be electrically disconnected, removed, and replaced with new elements. This made the previous method of repair more time consuming as well as very costly.

SUMMARY OF THE INVENTION The new improved method will overcome the perplexities caused by the use of castor oil. It has been found that the use of Di-Methyl Polysiloxane oil Silicone Oxide (SiO2) (DC-111) provides an excellent coupling over the entire surface of the transducer whereas castor oil fails to provide ev'en the minimumcoupling characteristics desired. 7

The consistence of Di-Me'thyl Polysiloxane oil silicone oxide (SiO2) compound hereafter referred to as DC-lll eliminates seepage and resultant dry spots. The consistency of DC-lll also eliminates the contamination of the exterior of the transducer which in turn reduces the overall resistance to ground. It has been found that transducers using DC-lll as a coupling agent have an increase in power output of about 3-5 db over transducers using castor oil. This present method eliminates the time requiredv to mechanically and electrically remove cavitated or oil soaked elements. Additionally, the use of the special heated chisel allows the element faces to be removed from the element laminations without any damage to the element faces. Consequently, new elements are not required for normal overhauls. Finally, the present inventive method eliminates the time required to test castor oil for low moisture content. The new method increases the performance in service time and reduces reworking time due to poor coupling.

STATEMENTS OF THE OBJECTS OF THE INVENTION The major object of the invention is to provide a more suitable and efficient method to reclaim old transducer elements. Another object of the invention is to provide a more suitable agent to repair old transducer elements.

' A more particular object of the invention is to provide a better energy transfer coupling and seal, thereby making it possible to reclaim old transducers.

Other objects and features will be apparent from the following description of the invention and from the accompanying drawings and flow diagram of the preferred embodiment of the present inventive method wherein:

FIG. 1 is a simplified drawing illustrating the modified soldering iron for stripping the element face plates;

FIG. 2 is a simplified drawing illustrating the boot expander and a detailed showing of the boot curled over the tension bolt;

FIG. 3 is a simplified drawing illustrating the basic transducer elements and the manual application of Compound DC-lll to the transducer elements;

FIG. 4 is a flow diagram of the disclosed method of repairing transducers; and

FIG. 5 is a simplified drawing illustrating the modified method of repairing transducers.

I In order to clearly understand the method of repairing a transducer, a discussion of the compound used in this method will be presented.

Di-Methyl Polysiloxane Oil Silicone Oxide (SiO2) sold under the trade name Dow Corning 1]] Compound or DC-lll (hereafter referred to as DC-lll), is a stiff, non-melting silicone material that maintains its consistency over a temperature range from about 40 to 500 F.

Because of its low volatility, chemical resistance and sealing ability it is commonly used as a sealant for vacuum and pressure systems and as a sealant and lubricant for chemical processing equipment. Nonoxidizing and non-gumming DC-l 1 l is used in pressure lubricated plug valves, control valves, flow meter bearings and ceramic plug locks. Moreover, because of its outstanding water resistance, it is used to lubricate valves of water softeners.

Water repellant and chemically resistant, the compound c'an be used as a seal for floating telephone batteries. It also serves as a lasting lubricant for synthetic rubber O-rings and seals in high temperature applications. The heavy consistency of the compound can be utilized to keep the rubber seals in position.

Although not previously used for this purpose, it has been discovered that DC-l 11 is extremely suitable for use as an energy couplant in sonar transducers and hydroplanes, as well as a repair material for the transducers if combined with a proper method of application.

Inasmuch as cavitation is the major cause of failure of sonar transducers, it has been found through testing of various compounds that compound DC--] 1 1, when properly applied, virtually eliminates the cavitation in most types of transducers.

REPAIR PROCEDURES USING DC-l 11 Referring to FIGS. 1 and 4 of the drawings the inventive method consists of stripping off all of the neoprene face plates using a heated chisel (step I). A modified soldering iron l has been successfully used and offers a simple method of face plate removal. The soldering iron used is an American Beauty Catalog No. 3178, which draws 300 watts. The copper tip (2) is modified to form a chisel with a steel edge. It should be noted that the steel edge is not essential, however, it greatly extends the life of the chisel. Returning to FIG. 4, after stripping the face plates (step I), it is necessary to clean the exposed laminations with a wire brush (step II). Next apply DC-l l 1 compound (step III) to all element faces by hand 11 (see FIG. 3). It is most important that the compound be placed over the complete radiating area of each element 11 in a smooth thin layer without the entrapment of any air bubbles. A fillet of the compound must be built up at the top and bottom of each element 11 to form a transition between the level of thenickel radiating face 9 and the level of theplastic separators 10. No attempt need be made to fillinterstave spaces 12 with DC-lll compound.

Referring to FIGS. 2 and 4, (step IV) consists of mounting a clean,dry boot 6 on aboot expander 3. Theboot 6 must be mounted on theexpander 3 so that the boot edge is level with the bottom edges of the expander bars 4. If this procedure is followed closely, the boot, with expander bar element still beneath it, will mount on the transducer as shown in FIG. 2 after the tension screws 8 are removed. Referring to FIGS. 4 and 5, there is a modification of the recited inventive method in which the boot is coated with DC-l l l on its interior surface (IVa). The boot coating is applied to the interior surface of the boot by placing DC-l I l (14) over one section of the interior (15) of theboot 10, running from top to bottom and then spreading it throughout the inner surface by placing the outside surface of the boot on a long,fiat surface 17 and rolling it (16) (such as a floor or long table) some distance across theflat surface 17, while the top surface is manually pressed to the bottom surface, forcing the interior sides to slide against one another. This procedure, when viewed from the side, resembles a collapsed tank tread being pushed ahead. Referring to FIG. 4, (step V) consists of using a standard vacuum of 27 inches inside the transducer to secure the boot tightly to the radiating surface and holding this vacuum for at least 24 hours. The boot should form a shape similar to that shown in FIG. 2. The steel bands are applied at the top and bottom areas only; (step VI). Care should be taken so that no bands extend over radiating surface areas. Finally, the vacuum is then reduced to the normal operational level of the transducer, that is 6 inches of vacuum, (step VII).

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

We claim:

1. The method of repairing old transducers including a transducer with face plates, radiation plates, separation plates, and interstave spaces comprising the steps of:

a. stripping the face plates of said transducer with a heated stripping means to expose said radiation plates, separation plates and interstave spaces;

b. cleaning said radiation plates, separation plates and interstave spaces with an abrasive cleaning means;

c. applying a Di-Methyl Polysiloxane Oil SiO2 to the radiation plates and separation plates;

(1. building a layer of Di-Methyl Polysiloxane Oil SiO2 compound at the top and bottom of said radiation plates to form a transition area between said radiation plates and the level of the separation plates;

e. mounting a dry boot over the coated radiation plates and separation plates of said transducer;

f. applying a standard vacuum to secure the boot to the transducer;

g. applying steel boot bands at the top and bottom of the boot; and

h. reducing said standard vacuum to the normal operational vacuum level of said transducer.

2. The method recited in claim 1 wherein the boot is coated with Di-Methyl Polysiloxane oil SiO2 compound on the interior surface of said boot.

3. The method recited inclaim 2 wherein the boot coating is applied by placing said Di-Methyl Polysiloxane over one section of the interior surface of said boot running from the top to the bottom of said boot interior and being spread throughout the inner surface of said boot interior by placing the outside surface of said boot on a flat surface, rolling the boot over said flat surface while pressing and sliding the top interior surface of said boot to the bottom interior surface of said boot.

4. The method recited in claim 1 wherein said standard vacuum is 27 inches and is applied for approximately 24 hours.

5. The method recited in claim 4 wherein the normal operational vacuum level of the transducer is reduced to about 6 inches of vacuum.

Claims (4)

1. 2. The method recited in claim 1 wherein the boot is coated with Di-Methyl Polysiloxane oil + SiO2 compound on the interior surface of said boot.
2. 3. The method recited in claim 2 wherein the boot coating is applied by placing said Di-Methyl Polysiloxane over one section of the interior surface of said boot running from the top to the bottom of said boot interior and being spread throughout the inner surface of said boot interior by placing the outside surface of said boot on a flat surface, rolling the boot over said flat surface while pressing and sliding the top interior surface of said boot to the bottom interior surface of said boot.
3. 4. The method recited in claim 1 wherein said standard vacuum is 27 inches and is applied for approximately 24 hours.
4. 5. The method recited in claim 4 wherein the normal operational vacuum level of the transducer is reduced to about 6 inches of vacuum.

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