US3595325A

US3595325A - Intermediary impact device

Info

Publication number: US3595325A
Application number: US819886A
Authority: US
Inventors: Charles C Libby; William J White
Original assignee: Ohio State University
Current assignee: Ohio State University
Priority date: 1969-04-28
Filing date: 1969-04-28
Publication date: 1971-07-27
Anticipated expiration: 1988-07-27

Abstract

This invention is an apparatus for transferring vibratorymechanical energy from an electromechanical transducer to a work surface by providing an intermediary impacting means which alternately contacts the work surface and the transducer. The intermediary impacting means is restrained for collinear movement by a flexible restraining means having a rigid support which is fixed to the nodal region of the electromechanical transducer.

Description

United States Patent [72] Inventors Charles C. Libby;

wiliiam J. White, both of Columbus, Ohio 819,886

Apr. 28, 1969 July 27, 1971 The Ohio State University Columbus, Ohio [21 1 Appl. No. [22] Filed [45 1 Patented [73] Assignee [54] INTERMEDIARY IMPACT DEVICE 9Claims,7DrawingFigs.

52 us.c1.' 173/117, 173/133, 175/56, 310/82 511 1111.01 ll0lv7/00 [so] FneldoiSearch 173/114, 1 17, 133; 175/56; 74/13, 18.2; 310/132 [56] References Cited UNITED STATES PATENTS 1,559,709 11/1925 Knapp 175/56 1,657,387 1/1928 Goldschmidt 173/133 X 1,855,446 4/1932 Goldschmidt 173/133 X 2,868,507 1/1959 Scott et a1 173/117 X 3,485,307 12/1969 Riley et a1 175/56 X Primary Examiner-Emest R. Purser Attorney-Anthony D. Cennamo ABSTRACT: This invention is an apparatus for transferring vibratory-mechanical energy from an electromechanical transducer to a work surface by providing an intermediary impacting means which alternately contacts the work surface and the transducer. The intermediary impacting means is restrained for collinear movement by a flexible restraining means having a rigid support which is fixed to the nodal region of the electromechanical transducer.

PATENTEUJULNIQYI 3,595,325

sum 1 OF 3 FIG. I

INVENTCJR CHARLES C. LIBBY WILLIAM J. WHITE BY ATTORNFY BY WILLIAM J-NHITE ATTORNEY INTERMEDIARY IMPACT DEVICE CROSS REFERENCES AND BACKGROUND There is disclosed in Pat. No. 3,396,285, for Electromechanical Transducer, by I-Iildegard M. Minchenko, a transducer capable of delivering extremely. high power, i.e., measurable in horsepower (or kilowatts) at an acoustical frequency range. The principle underlying the high-power output is in the structural arrangement of the components immediately associated with the piezoelectric driving elements. In theory and practice, the piezoelectric elements are under radial and axial pressure that assure that they do not operate in tension even under intense sonic action. Significantly, the structural design of this transducer, that permits the extraordinary power output from the driving elements, resides in the novel method of clamping the piezoelectric elements both radially and longitudinally (axially). In this way the acoustic stresses in the piezoelectric elements are always compressive, never tensile, even under maximum voltage excitation.

The transducer disclosed in the aforementioned patent is in tended, and therefore utilized, to deliver a steady-state vibratory power output signal. That is, the piezoelectric assembly is a component of a resonant structure that will produce a mechanical vibratory output at the frequency of the driving electrical signaland vice versa.

There is disclosed in the copending patent application, for Sonic Transducer Assembly", Ser. No. 713,030now abandoned, filed Mar. 14, 1968, by Robert C. McMaster, Charles C. Libby, and Keith Likins, and assigned to The Ohio State University, an improved enclosure design for a sonic or ultrasonic transducer. More specifically, the enclosure design is for a resonant structure type of sonic transducer that completely encloses the transducer but yet does not affect the electrical or mechanical characteristics thereof. The enclosure covers the entire structure and even though it is clamped to the structure of the transducer the enclosure permits the nonrestrictive movement of the transducer tip. The enclosure follows the outside contour of the transducer and is fixedly clamped to the transducer at its node (point of minimum amplitude). The top portion of the enclosure is closed, whereas the bottom of the enclosure has an opening to permit vibration of the transducer horn without contact with the housing.

There is disclosed in US. Pat. No. 3,475,628, for Sonic Transducer Apparatus", by Robert C. McMaster, et al., a utilization of the aforementioned sonic transducer in a work environment. Resonant structures, although having the capability of delivering high power outputs, have not in actual practice proven themselves. It is known that when a resonant transducer is coupled to a work tool or to a work piece, there is a shift in frequency. That is, the structure is no longer resonant at the excitation frequency. In this particular means of coupling a work tool or workpiece to a transducer is accomplished without a shift in frequencythe transducer retains its power capabilities as though it were resonating in free space. The particular means is an intermediary device that impact couples the transducer to the work tool.

Further, it has been disclosed in copending patent application for Power Conversion Means", Ser. No. 713,034, filed Mar. 14, 1968, by Robert C. McMaster and assigned to The Ohio State University, an apparatus wherein an impact coupling means may be used as an intermediate mechanical member for transmitting the vibratory-mechanical energy from one transducer to another. The intermediate mechanical member for so transmitting the vibratory-mechanical energy is held in position by a diaphragm spaced between two opposing transducers of the system of the invention.

Summary of the Invention The present invention is a device for effectively delivering vibratory-mechanical energy from the tip of the horn of an electromechanical transducer to a work surface. In the system of the present invention an intermediary impact device is positioned against the tip of an electromechanical transducer. The vibratory-mechanical energy of the transducer is concentrated at the tip of the transducer causing the tip to extend and contract in the axial direction. Therefore, the transducer tip impacts the intermediary impact device and drives the impact device against the surface of the material to be formed or against a tool. The movement of the impact device is constrained to movement collinear with the axial direction of movement of the transducer tip by means of a dual diaphragm made of metal or of an organic material.

The transducer tip impacts against the intermediary impact device driving the impact device away from the transducer tip. The dynamic energy of the impact device moving away from the transducer tip is absorbed upon impact with the work surface of tool. After the dynamic energy is substantially absorbed by the work material or the diaphragms, the impact device recoils returning to the transducer tip where the device is impacted again by the transducer tip. During the impacting cycle of theintennediary impact device, the dual diaphragm Objects The principal object of the present invention is to provide an apparatus for conveniently holding an intermediary impact device which can do useful work with an electromechanical transducer as the driving force.

Another object of the invention is to provide an apparatus for controlling the initial static force between the intermediary impact device and the electromechanical transducer tip.

Another object of the invention is to provide an apparatus for controlling the impact force between the intermediary impact device and the work surface.

Another object of the invention is to provide an apparatus to prevent cocking of an intermediary impact device due to imbalanced forces developed at the work interface.

Still another object of the invention is to provide an apparatus for constraining the travel of an intermediary impact device to a path collinear with the axial movement of the transducer tip.

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

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view of an intermediary impacting device positioned in conjunction with a piezoelectric electromechanical transducer and transmission line; the intermediary impacting device is essentially a dynamically independent tool in a unitary mechanism in which the intermediary impacting device is suspended by a double diaphragm arrangement;

FIG. 2a is a top view of the clamping arrangement for securing the flexible diaphragms of the intermediary impacting device to the nodal diaphragm support;

FIG. 2b is a side view of the clamping arrangement for securing the flexible diaphragms of the intermediary impacting device to the nodal diaphragm support;

FIG. 3 is a pictorial illustration of the construction of the intermediary impacting device showing the flexible diaphragms and dynamic tool;

FIG. 4a is an illustration of the intermediary impacting device positioned relative to the transmission line whereby a compressive bias between the impacting device and the transmission line is exerted by the double diaphragm;

FIG. 4b is an illustration of the intermediary impacting device positioned relative to the transmission line whereby no bias force is exerted by the double diaphragm; and,

FIG. 4c is an illustration of the intermediary impacting device positioned relative to the transmission where an external bias force deflects the intermediary impact device against the transmission line.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring generally to FIG. 1 there is shown a schematic drawing of the preferred embodiment of the invention. An electromechanical transducer 1 is supported at its node 2 by a clamp 3 which secures the transducer 1 to both a machine frame 4 and the nodal diaphragm support 5. Twin parallel flexible diaphragms 6 are secured to nodal diaphragm support 5 by nuts 7. The flexible diaphragms 6 are separated by spacers 8. The dynamic tool 9 or intermediary impacting device 9 is secured to the flexible diaphragms 6. The diaphragms 6 hold the dynamic tool 9 in some predetermined position relative to a vibratory-mechanical energy transmission line 10.

The apparatus of the present invention provides a means for utilizing the impact coupling principle in transferring vibratory-mechanical energy from the electromechanical transducer 1 to a work surface. Use of the impact coupling principle ensures that the mass associated with the dynamic tool 9 and the nodal diaphragm support 5 will not substantially effect the resonant characteristics of the electromechanical transducer 1. That is, the free running characteristics of the transducer 1 will not be substantially altered. This is due to the fact that the dynamic tool 9 and/or the work material does not couple" with (become essentially a part" of) the transducer thereby driving it out of resonance with the input frequency at which the transducer 1 was designed to operate. A detailed consideration of the "coupling phenomenon is set forth in copending patent application for Combination and Process to Compact Powdered Metals Using Sonic Agitation", Ser. No. 730,367, filed, May 20, 1968, by Charles C. Libby and assigned to The Ohio State University.

The twin flexible diaphragm 6 arrangement was illustrated in FIG. 1 performs essentially three functions. The diaphragm (1) supports the dynamic tool 9, (2) enables the dynamic tool 9 to be positioned with respect to the transmission line 10, and (3) constrains the dynamic tool with the movement of the transducer I tip.

The nodal diaphragm support 5 in conjunction with the flexible diaphragms 6 retains the dynamic tool 9 in position. This combination, then, is a dynamically independent tool in a unitary mechanism which includes the power source, the transducer 1. With the dynamic tool 9 so positioned and affixed the utility and versatility of the electromechanical transducer 1 is enhanced since the

transducer tool assembly

1, 5, 6, 9, may be operated while positioned in any desired manner. That is, the transducer 1 and the dynamic tool 9 may be made to perform useful work in a vertical position, a horizontal position or any position in between. In addition, the flexible diaphragms 6 in conjunction with the nodal diaphragm support 5 forms an enclosing structure around the transducer 1 horn. This enclosing structure seals the transducer 1 horn off from any corrosive or hostile elements of the environment in which it is used. The nodal diaphragm support 5 and the flexible diaphragms 6 are constructed of materials which are impervious'or highly resistant to the environment in which the tool is to be used. The enclosure design herein above described is an extension of the enclosure design disclosed in the copending patent application for Sonic Transducer Assembly", Ser. No. 713,031, filed Mar. 14, 1968, now abandoned in continuation application Ser. No. 14,770, filed Feb. 27, 1970 by Robert C. McMaster, Charles C. Libby and Keith Likins, and assigned to The Ohio State University.

A predetermined bias force may be exerted on the dynamic tool 9 by regulating the position of the nodal diaphragm diaphragm support 5 with respect to the transmission line 10. FIG. 1 illustrates the dynamic tool 9 and nodal diaphragm support 5 positioned relative to the transmission line 10 so as to create a compressive bias between the dynamic tool 9 and the transmission line 10.

FIGS. 40, 4b and 4c illustrate the three basic positions which the dynamic tool 9 may assume relative to the transmission line 10. FIG. 4a illustrates compressure bias illustrated and described in conjunction with FIG. 1 above. FIG. 4b illustrates positioning of the dynamic tool 9 and nodal diaphragm support 5 relative to the transmission line 10 with no bias loading on the dynamic tool 9. That is, the diaphragms retain the dynamic tool 9 in a neutral or no load" position. FIG. 4c illustrates the dynamic tool 9 and the nodal diaphragm support 5 positioned so as to support the dynamic tool 9 at a distance from the transmission line 10 but for the application of an external bias force, F. The external bias force, F, deflects the dynamic tool 9 and double diaphragm 6 placing the dynamic tool 9 in contact with the transmission line 10.

The amount of tension or initial contact pressure between the dynamic tool 9 and the transmission line 10 is attributable to the displacement of the flexible diaphragms'6 from the neutral position. Where the compressive bias (FIGS. 1, 4a) is used. The preload or initial contact pressure between the dynamic tool 9 and the transmission line 10 contributes to the operating characteristics of the apparatus in the work environment. More specifically, the amount of initial contact pressure affects the distance that the dynamic tool 9 will travel away from the interface 12 between the dynamic tool 9 and the transmission line 10. As the initial contact pressure is increased the frequency at which the dynamic tool 9 vibrates increases. The increased contact pressure shortens the stroke of the dynamic tool 9 and increases the velocity at which the dynamic tool 9 is returned to the transmission line 10 thereby increasing the operating frequency of said dynamic tool 9.

The transmission line 10 as illustrated in FIG. 1 is not essential to the operation of the apparatus. That is, the dynamic tool 9, flexible diaphragm 6, and nodal diaphragm support 5 may be altered in size so as to position the dynamic tool 9 directly in front of or against the transducer I tip; in such an embodiment the transmission line 10, of course, may be omitted. However, where a transmission line 10 is used, the behavior or operating characteristics of a transmission line 10 may be ascertained by consulting copending patent application for Sonic Transmission Line", Ser. No. 637,306, filed May 9, 1967, now abandoned in continuation application Ser. No. l, 957, filed Mar. 4, 1970 by Charles C. Libby and Karl F. Graff and assigned to The Ohio State University.

The twin diaphragms 6 perform a most important function in keeping the path that the dynamic tool 9 travels colinear with the axial movement of the transducer I tip or with the axial movement of the transmission line 10 as in the case of the illustration of the preferred embodiment in FIG. 1. That the diaphragms 6 constrain the travel of the dynamic tool 9 along a path collinear with the axial movement of the trans ducer I tip or the transmission line 10 enables the dynamic tool 9 to be used much more accurately in many application. The twin diaphragms 6 also serve to prevent the dynamic tool 9 from canting or cocking as it travels the path which is collinear with the axial movement of the transducer 1 tip. Observe, that the twin diaphragm 6 arrangement described in conjunction with the preferred embodiment of the invention is not intended to limit the application said twin diaphragm 6 arrangement. In lieu of the twin diaphragms 6, a plurality of more than two diaphragms or a single diaphragm of sufficient thickness and elastic properties may be used.

FIGS. 2a and 2b illustrate the clamping arrangement used to secure the flexible diaphragms 6 to the nodal diaphragm support 5. FIG. 2a is the top view of FIG. 2b. FIG. 2b illustrates in detail the clamping arrangement described generally in conjunction with FIG. 1. The spacers 8 separate the flexible diaphragms and keep them a predetermined distance apart. The nuts 7 clamp the spacers 8 against the diaphragms 6 firmly securing the diaphragms 6 in position. FIG. 3 illustrates the diaphragm 6 and dynamic tool 9 assembly.

The diaphragms 6 are attached in any manner which firmly secures said diaphragms 6 to said dynamic tool 9. Where both the dynamic tool 9 and diaphragm 6 are metallic or organic material, the two components may be secured together by welding. Where the dynamic tool 9 and the diaphragms 6 are dissimilar material the two components are secured together by brazing or as explained hereinafter. In the preferred embodiment, the diaphragms are secured to the dynamic tool 9 by making the dynamic tool 9 a layered construction. This layered construction is like the spacer arrangement used to secure the diaphragms 6 to the nodal diaphragm support 5. Referring to FIG. 2b, the diaphragms 6 are positioned between the spacers l3, l4, 15, which comprise the dynamic tool 9. The spacers l3, l4, l5, and the diaphragms 6 between them are secured together by threaded fasteners or pins which make an interference fit with holes drilled for them in the spacers l3, 14, 15.

The dynamic tool 9 may be used to form various geometries as where the dynamic tool 9 is machined as a die for forming a chosen configuration. Impacting a work material with the dynamic tool 9 made in the form of a die against a static tool having a desired geometry produces an accurately formed object of the chosen geometry. Further, using the apparatus of the present invention object may be formed using static pressures on the order of 10 to lOO times less than those pressures required for forming materials using the apparatus and techniques disclosed in the prior art. The theory on which the operation of the present invention at such low static pressures is predicated is further disclosed in copending patent application for A Process for the Cold Forming of Metal", Ser. No. 713,036, filed Mar. 14, 1968, by Robert C. McMaster and assigned to The Ohio State University.

Although certain and specific embodiments of the invention have been illustrated and described, it is understood that modifications thereto may be made without departing from the true scope and spirit of the invention.

What we claim is:

l. A combination for transferring sonic/ultrasonic vibratory-mechanical energy to a work surface comprising a resonant piezoelectric vibratory-mechanical energy source, said resonant transducer including a force concentrator, means for electrically exciting said vibratory mechanical source at its resonant frequency, an intermediary impact device for transferring substantially all of said vibratory-mechanical energy to a work material, flexible restraining means for spatially positioning said impact device adjacent said force concentrator and for restraining said intermediary impact device to movement solely in directions collinear with the movement of said vibratory-mechanical energy source, means rigidly fixed to the nodal region of said resonant source for supporting said flexible restraining means.

2. A combination as set forth in claim 1 wherein said resonant vibratory-mechanical energy source further comprises a half-wave vibratory-mechanical energy transmission line which is attached to said force concentrator end of said piezoelectric electromechanical transducer.

3. A combination as set forth in claim 1 wherein said intermediary impact device for transferring said vibratorymechanical energy is a mass having a predetermined shape.

4. A combination as set forth in claim 1 wherein said means for restraining said means for transferring said vibratorymechanical energy to movement solely in directions collinear with the movement of said source of said vibratory-mechanical energy is a plurality of flexible diaphragms securely attached to said means for transferring said vibratory-mechani cal energy whereby cocking of said means for transferring said vibratory-mechanical energy is eliminated.

5. A combination as set forth in claim 1 wherein said means for restraining said means for transferring said vibratorymechanical energy to movement solely in directions collinear with the movement of said source of said vibratory-mechanical energy further comprises a single diaphragm of sufficient thickness to prevent cocking".

6. A combination as set forth in claim 1 wherein said rigid means for supporting said restraining means further comprises an enclosing structure thereby protecting the vibratorymechanical energy source.

7. A combination as set forth in claim 1 wherein said combination further comprises means for subjecting said restraining means to a compressive bias force between the dynamic tool and the transmission line.

8. A combination as set forth in claim 1 wherein said combination further comprises means for subjecting said restraining means to an external bias force by which the dynamic tool is forced against the transmission line.

9. A combination as set forth in claim 1 wherein said combination further comprises means for maintaining said restraining means undeflected from the neutral position.

Claims

1. A combination for transferring sonic/ultrasonic vibratorymechanical energy to a work surface comprising a resonant piezoelectric vibratory-mechanical energy source, said resonant transducer including a force concentrator, means for electrically exciting said vibratory mechanical source at its resonant frequency, an intermediary impact device for transferring substantially all of said vibratory-mechanical energy to a work material, flexible restraining means for spatially positioning said impact device adjacent said force concentrator and for restraining said intermediary impact device to movement solely in directions collinear with the movement of said vibratorymechanical energy source, means rigidly fixed to the nodal region of said resonant source for supporting said flexible restraining means.

3. A combination as set forth in claim 1 wherein said intermediary impact device for transferring said vibratory-mechanical energy is a mass having a predetermined shape.

4. A combination as set forth in claim 1 wherein said means for restraining said means for transferring said vibratory-mechanical energy to movement solely in directions collinear with the movement of said source of said vibratory-mechanical energy is a plurality of flexible diaphragms securely attached to said means for transferring said vibratory-mechanical energy whereby ''''cocking'''' of said means for transferring said vibratory-mechanical energy is eliminated.

5. A combination as set forth in claim 1 wherein said means for restraining said means for transferring said vibratory-mechanical energy to movement solely in directions collinear with the movement of said source of said vibratory-mechanical energy further comprises a single diaphragm of sufficient thickness to prevent ''''cocking''''.

6. A combination as set forth in claim 1 wherein said rigid means for supporting said restraining means further comprises an enclosing structure thereby protecting the vibratory-mechanical energy source.