US3475628A

US3475628A - Sonic transducer apparatus

Info

Publication number: US3475628A
Application number: US605284A
Authority: US
Inventors: Robert C Mcmaster; Charles C Libby; Hildegard M Minchenko
Original assignee: Ohio State University
Current assignee: Ohio State University
Priority date: 1966-12-28
Filing date: 1966-12-28
Publication date: 1969-10-28
Anticipated expiration: 1986-10-28
Also published as: GB1217859A; GB1217860A; DE1597006A1; FR1548215A; CH487679A

Description

Oct. 28, 1969 C T ET AL 3,475,628

SONIC TRANSDUQER APPARATUS Filed Dec. 28, 1966 INVENTOR. ROBERT C. M MASTER CHARLES C LIBBY BY HILDEGARD M. MINCHEMO m GE United States Patent SONIC TRANSDUCER APPARATUS Robert C. McMaster and Charles C. Libby, Columbus,

and Hildegard M. Minchenko, Reynoldsburg, Ohio, assignors to The Board of Trustees of the Ohio State University, Columbus, Ohio, an institution of higher learning of Ohio Filed Dec. 28, 1966, Ser. No. 605,234 5 Int. Cl. H04r17/10 U.S. Cl. 310-82 11 Claims ABSTRACT OF DISCLOSURE 1 This invention relates generally to means of utilizing in a work environment a high-power, high-Q electromechanical transducer; and particularly means of loading a high-power electromechanical transducer, that is, coupling a high-power electromechanical transducer to a tool in a work environment. 7

CROSS REFERENCES AND BACKGROUND Thereis disclosed in the copending application filed by Robert-C. McMaster and Berndt B. Dettlolf, Ser. No. 508,812, for Transducer, a sonic transducer that combines the driving element (piezoelectric) with the mechanical displacement amplifier (horn) in a novel way. The transducer therein disclosed is a high-Q transducer, exceptionally rugged, compact, and capable of carrying continuous work loads. Still, and most significantly, in another copending application Ser. No. 571,490, filed Aug. 1110, 1966, for Electromechanical Transducer, by Hildegard M. Minchenko,..and assigned to the same assignee, there is disclosed a transducer capable of delivering extremely high power, i.e., measurable in horsepower (or kilowatts) in, an acoustical frequency range. The structural design of the transducer permits extraordinary power output from. the driving elements. Through the clamping-of the piezoelectric elements, bothv radially and longitudinally (axially), the acoustic stresses in the piezo electricelements are always compressive, never tensileeven undermaximum voltage excitation.

, There is further disclosed in the copending application filed Nov. 19, 1965, for Sonic Generator, Ser. No. 508,804, by R. C. McMaster and C. C. Libby, and assigned to the same assignee, a generator directed to the utilization of the generated force as a work load. More specifically there is disclosed a transmission-line means adapted forcoupling Onetransducer to another for work transfer.

An electromechanical transducer such as that disclosed in the-aforementioned. copending applications will have full-power capabilities when permitted to vibrate at its resonant frequency. It has now been found in practice that coupling the transducer to a workpiece, such as coupling the tip of the horn to a tool, will drastically reduce thepower capabilities of the transducer if (1) the input frequency is constant and (2) the load characteristics (mass and compliance) constitutes a mismatch to the resonant structure of the transducer. The explanation for this is quite simple: the tool, when attached, becomes a part of the structure in general and the structure there- BRIEF- SUMMARY The present invention is directed to means of efiiciently coupling a high-power, high-Q electromechanical transducer to drive a tool effectively, i.e., to drive the tool in a 'work environment. In a first arrangement, the significant feature of the invention is that the tool does not form a part of the transducer resonant structure, thereby permitting the transducer to develop full-power capability 3,475,628 Patented Oct. 28, 1969 at its resonant frequency. In an alternate arrangement, means is provided for effectively coupling a high-Q transducer to work surfaces having various configurations. The transducer is especially utilized in driving thin surfaces, sheets, and plates; and wherein the resonant frequency of the transducer in general is not the same as any of the resonant frequencies of the work surfaces.

OBJECTS It is accordingly an object of the present invention to provide novel method and means of utilizing a highpower transducer in a work environment.

Another object of the present invention is to provide novel method and means for coupling a high-Q transducer to tools in a work environment without a loss of power capability while utilizing a constant-frequency supply.

A further object of the present invention is to provide novel method and means of coupling a high-Q transducer to Work surfaces having various configurations.

Still another object of the present invention is to provide means of delivering high power to a work area that is simple, rugged and adaptable to most any type of highpower high-Q transducer.

Other objects and features of the present invention will become apparent from the following detailed description when taken in conjunction with the drawings in which:

BRIEF DESCRIPTIONS OF THE VIEWS OF THE DRAWINGS FIGURE 1 is a first embodiment of the present invention illustrating coupling of a high-power transducer to a workpiece;

FIGURE 2 is the embodiment of FIGURE 1 in a different work environment;

FIGURES 2a and 2b illustrate practical embodiments of the arrangement shown in FIGURE 2;

FIGURE 3 is another embodiment of the present invention illustrating coupling of a high-power transducer to a workpiece;

FIGURE 3a illustrates a practical embodiment of the arrangement shown in FIG. 4; I

FIGURE 4 is still another embodiment of the present invention illustrating coupling of a high-power transducer to a workpiece;

FIGURE 5 is another embodiment of the present invention illustrating coupling of a high-power transducer to a workpiece;

FIGURES 6, 6a are other embodiments of the present invention illustrating coupling of a high-power transducer to a workpiece; and,

FIGURE 7 is still another embodiment of the present invention illustrating coupling of a high-power transducer to a workpiece.

DETAILED DESCRIPTION Referring now to the figures generally, there is shown the method vand means of coupling the high-power, high- Q transducer, i.e., the tip of the horn, to either the work tool or directly to the workpiece. The significant achievement is that in each instance the transducer is capable of delivering a greater portion of its power capacity to perform useful work than when using conventional means of coupling.

Referring now specifically to FIGURES 1 and 2 there is provided on the tip of the horn 10 of the transducer 5 a collar 7 shown in cross-section in FIGURE 1 and in perspective in FIGURE 1a. This collar 7 may "be in the form of a nut in threaded engagement with the tip 10 of the transducer or alternatively may be integral with the horn-tip assembly or shrink or press-fitted thereon. FIGUR ES 2a and 2b show alternate arrangements for retaining the pin 11 within the collar '7. In FIGURE 2a the collar 70 has a shoulder 7a to contain the longitudinal motion of the pin 11a by the head 11cthe distance between the shoulder 7a and the tip of the horn being suflicient to maintain vibrational motion of the pin 11a. The collar 70 in this instance is screwed on the tip of the horn with the pin 11a in place. In FIGURE 2b the arrangement is similar to that of FIGURE 2a except the grommet 7d may be of rubber or the like and press-fitted into the collar 7b adjacent tip of the horn. Similarly, the pin head 110 or pin 11b may be forcefitted through the opening to rest on the grommet 7d.

In FIGURE 3 the tool 9 has a longitudinal aperture 13 formed therein. Also a longitudinal aperture 12 is formed in the underside of the tip of the horn 10. The two apertures 12 and 13 are longitudinally aligned with each other to receive and retain the pin 11. The pin 11 has a cross diameter somewhat less than that of the inside diameter of the two apertures. In this way, in operation, the pin 11 is retained but not restrained from longitudinal vibration in any way.

The pin 11 need not be metallic but can be constructed of either elastic or rigid material. Also as shown in FIGURE 30:, to prevent wear on the tip of the horn 10, there is provided a one-half wave extension 15 in threaded engagement as shown at 17 with the tip of the horn. Accordingly, the wear is taken by the extension and, when it becomes severe, the extension is replaced.

In FIGURE 4 there is shown still another arrangement for coupling the tip 18 of the horn of the transducer 5. In this instance the work tool is enlarged and has an aperture 15a formed therein. The enlargement 15 is larger than the tip of the horn of the transducer to permit physical contact without restraint on the transducer.

Of significance in operation of the transducers having the modifications shown in FIGURES l, 2, 3, and 4 is that there is no direct coupling of the transducer-the tip of the hornto either the work tool or to the workpiece. In each instance there is freedom of movement between the transducer and the workpiece. Accordingly, since there is no added structure to the transducer, its resonant length and frequency is unaffected.

More specifically in operation, referring again to FIG- UR'E 1, the transducer is shown as driving a nail, pin, stake, etc., 6 into another substance-the workpiece 3. With each impact the driven element 6 will move in one direction with little or no return motion. In this instance the transducer bounces back; that is, the return motion is in the transducer.

=In FIGURE 2 the operation is indirect, that is, the tool 4 performs the work on the workpiece 3. However, in this instance, the forward and return motion is taken up entirely by the tool 4. In other words, the tool 4 bounces back and forth within the confined region with each impact. The impacts of the tool relative to the workpiece do not necessarily occur with each forward movement of the tip of the horn of the transducer. The relative motion between the tool face and the transducer tip may occur (1) due to the compression of the tool face at the instant of the impact or (2) due to this compression plus a gross motion of the tool mass. In either case the motion of the tool face disconnects the tool from the transducer after each impact.

In a preferred constructed embodiment it was believed that impact between the tool and work surface occurred less frequently than one in ten cycles of resonant frequency of the transducer. It was further believed that impact rate has proved to be significant in making possible the delivery of high energy levels from a high-Q transducer to a work environment.

The operation of the transducer shown in FIGURE 3 is similar to that of FIGURE 2-the pin 11 forming in this instance the tool for performing the work on the workpiece. Again as in FIGURE 2 the forward and return motion is taken up by the pin 11. Alternatively,

as pointed out above, the pin 11 may serve simply as a pin and the work tool 9 may be the working element. .In this way the pin maintains the proper alignment. But, in either instance, there is no continuous direct contact between the transducer and the workpiece. The contact is intermittent and is of a duration (at each impact) of less than an one-half cycle of the transducer resonant frequency.

In a practical working embodiment shown in FIGURE 3a it has been found expedient to utilize a one-half wave (of the resonant frequency of the transducer) extensions between the tip of the horn and the working end such as shown in FIGURE 2. With this practical arrangement there is no direct wear on the tip of the resonant horn structure.

Referring now to FIGURES 5, 6, and 7, there is shown other means of coupling the transducer to a workpiece. In the transducer modifications shown in these figures there is significant difference in that a tool or adapter is fixed or permanently mounted to the workpiece. Particularly, in contradistinction to the tool arrangement in FIGURES l-4, the tool fastened on the tip of the transduceras pointed out hereinafter-is welded or clamped to the workpiece. But again, although there is direct contact, the addition of the work tool or adapter workpiece makes possible the delivery of high amounts of energy into relatively thin plates of work-surface material.

Specifically there is shown in FIGURE 5 the tip of the horn of the transducer 5 being fastened at 19 to the work area 3. The work area 3 in this instance is a flat sheet. In operation the work motion applied to the work area 3 will be in the horizontal or planar direction as shown by the arrows. However, it is to be noted that the direction of coupling of the transducer 5 to the sheet 3 is neither in the horizontal or vertical directions to the sheet surfaceit is at an angle somewhere between. Again in operation-the source power is effectively delivered by the transducer to the work surface. The work surface is caused to move by each impulse in a direction not in line with the longitudinal axis of the transducer. Further the resonant frequency of the transducer is not matched to the many resonant frequencies of which the plate is capable. In this way there is effective coupling, permitting a flow of sonic energy from the transducer into the plate. The junction of the plate and the transducer presents an impedance mismatch to a sonic energy flow from the transducer. This junction therefore becomes an antinode, vibrating at maximum amplitude at the resonant frequency of the transducer and tool. The same junction does not present a major change in impedance to the flow of sonic energy within the plate at any of the many resonant frequencies of which the plate is capable. Therefore the transfer of sonic energy from the plate back to the transducer is minimized.

The arrangement shown in FIGURE 6 is similar to that of FIGURE 5 except that the work area 3 in this instance is a tubular structure 3.

In the arrangement of FIGURE 7 the tool 19 is of a hollow conical shape. As pointed out relative to FIG- URE 5 the forward and return motion is in the planar direction, i.e., as shown by the arrows. Hence in this embodiment the coupling of the transducer tip 10 is in a vertical direction to maintain spatial (out-of-line) relationshipdescribed above-between transducer and tool.

The arrangements shown in the various figures have been adapted to earth-moving blades, penetrating solid materials, and for various drilling and riveting operations.

It is understood that modifications and departures may be had from the actual structures shown within the scope of the invention.

What is claimed is:

1. In combination with a resonant high-power, high-Q electromechanical transducer and a workpiece, the improvement of load coupling between the transducer to the workpiece comprising a tool for impacting the workpiece, means for coupling the tool to the transducer, said means maintaining nonrestrictive intermittent engagement of said tool to said workpiece at a rate less than the frequency of said resonant structure, thereby permitting freedom of movement between said transducer and said workpiece.

2. The combination of claim 1 wherein said means for coupling said tool to said transducer includes means for frequency-conversion of vibratory energy with high power transfer efliciency from said high-Q, high-power resonant transducers to said tool vibrating at a frequency other than the frequency of said resonant structure.

3. The combination of claim 1 wherein the nonrestrictive intermittent engagement permits the impact return motion of the tool after impact with the work surface to be absorbed by said transducer.

4. The combination of claim 1 wherein the nonrestrictive intermittent engagement permits the impact return motion of the tool after impact with the work surface to be absorbed by said tool.

5. The combination of claim 1 wherein the structure of said transducer includes an elongated element capable of transferring the Work energy, and wherein said nonrestrictive coupling of said tool to said transducer comprises a collar permanently fixed to the tip of said elongated portion of said transducer element and wherein said collar overextends beyond said tip, the opening in said overextended portion adapted to receive and nonrestrictively maintain said tool.

6. The combination of claim 1 wherein the structure of said transducer includes an elongated element capable of transferring the Work energy, and wherein said nonrestrictive coupling of said tool to said transducer comprises a first aperture longitudinally formed in said tip of said transducer, a second aperture longitudinally formed in one end of said tool, said first and second aperture in longitudinal alignment with each other, a pin having an outside diameter less than the inside diameter of said apertures, and wherein said pin when positioned in said apertures nonrestrictively maintains said tool in work transfer alignment with said transducer.

7. The combination of claim 1 wherein the impact between said tool and said work surface occurs less frequently than one in ten cycles of resonant frequency of the transducer.

8. The combination of claim 5 wherein the opening in said overextended portion of said collar further comprises retaining means for retaining said tool in longitudinal alignment with said elongation of said transducer.

9. The combination of claim 8 wherein said retaining means further includes a shoulder for retaining a capped tool in said collar.

10. The combination of claim 9 wherein said shoulder is of elastic material to permit the forceful removal of said capped tool.

11. The combination of claim 1 wherein the structure of said transducer includes an elongated element capable of transferring the work energy, wherein said nonrestrictive coupling of said tool to said transducer comprises an aperture formed in one end of said tool, and wherein said aperture has an inside diameter slightly greater than the outside diameter of said tip of said transducer.

References Cited UNITED STATES PATENTS 2,514,080 7/1950 Mason 710-83 2,651,148 9/ 1953 Carwile 51-59 2,680,333 6/1954 Calosi 51-59 2,774,193 12/1956 Thatcher 51-59 2,831,295 4/1958 Weiss 51-59 3,368,085 2/1968 McMaster 310-82 3,394,274 7/1968 Jacke 310-82 3,396,285 8/ 1968 Minchenko 310-8.2

J. D. MILLER, Primary Examiner US. Cl. X.R.